General Anaesthesia

Balanced Anesthesia

General anesthesia or in a simpler word “anesthesia” consists of a state of controlled unconsciousness (“hypnosis”) and pain relief (“anesthesia”) which is often referred to as “balanced anesthesia”. The condition is controlled and adjusted by anesthesia personnel using several different anesthetic drugs and is used to allow surgical or other stressful invasive procedures during “sleep without painful sensation”. Previously, the main components used for balanced anesthesia were a hypnotic for induction, a volatile anesthetic agent for the maintenance of anesthesia, an analgesic (a strong opioid) and a muscle paralyzing agent (muscle relaxant). These four agents constitue the basis of anesthesia and how to use and control these agents in a controlled and safe way is the very foundation of balanced anesthesia.

The use of anesthetics has changed in recent years, but it is still true that balanced anesthesia means being able to put the patient in a state of controlled unconsciousness where the surgeon is given the opportunity to perform surgery or other invasive procedures under stable conditions and to preserve the patient’s various organ functions optimally with regard to physiology. It can be said that the role of the anesthesiologist is to maintain “optimal homeostasis” in the patient during the invasive procedure.

By optimal homeostasis is meant that despite external influences, through surgery and the various effects of anesthetics can maintain a constant internal environment that is compatible with normal function of the organism, which in humans includes vital parameters such as heart rate, blood pressure, temperature, extracellular fluid volume, blood volume, cardiac output, macro- and microcirculation, osmolarity and electrolyte concentration, as well as concentrations of hydrogen ions (pH), glucose, oxygen, and carbon dioxide. We must compensate for blood and fluid losses and maintain normal physiological conditions in the patient as far as possible. The patient must be able to stay in an unconscious state without any movement for many hours in an unnatural way without being hurt. Anesthesia and the degree of unconsciousness should be adequate and under control throughout the procedure. The patient should never be too shallow or too deeply anesthetized and the condition should be able to be reversed in a controlled and safe manner.

The balanced anesthesia is controlled by balancing physiology and pharmacology under the influence of surgery, invasive procedures or trauma. During anesthesia, we work mainly with cardiovascular physiology and respiratory physiology, but also other functions such as immune systems and hormonal systems that are affected by general anesthesia.

In order to be able to provide a balanced anesthesia, adequate monitoring of the patient’s alertness and physiology is required – surveillance by good monitoring. The degree of monitoring is adapted to the nature and time of the procedure as well as the patient’s condition and actual state. Patients in good condition with ASA class I usually do not need the same surveillance as a patient with ASA class IV. A larger and more extensive surgical procedure naturally requires more extensive monitoring than simple surgical procedures. Elderly and fragile patients also usually require more supervision than young strong patients, but not always. As a rule, the monitoring and set-up are standardized according to the procedure and then adjusted with regard to the individual patient. Each specific procedure has a special “set-up” at each hospital that is described in special MM or directions.

Patient positioning and posture

It must be possible to handle the patient’s body position under general anesthesia, ie create good conditions for the surgeon to work while the patient must be able to overcome an unnatural body position without movements for sometimes many hours without getting hurt, for example in the form of compartment syndrome, pressure ulcers, pulmonary atelectasis, bladder tamponade or neuralgia (loss of sensation). The body positioning of a patient under anesthesia is a shared responsibility between the surgeon side and the anesthesia side. As far as possible, the arrangement is made while the patient is awake, but parts are made with the patient anesthetized. Some postures in special positions can only be maintained for a limited time, for example Trendelenburg position with high position of the legs can risk insufficient circulation in the lower extremities if it remains for too long.

Monitoring

The basis of monitoring under anesthesia is continuous measurement of vital parameters such as heart rate, blood pressure, ECG and oxygen saturation. Measurement is also made of muscle tone when using muscle relaxants (NMT). This is augmented as needed with monitoring of a more invasive nature such as intraarterial continuous blood pressure via arterial catheter, central venous pressure, BIS and other measurement of central hemodynamics. Parts of the monitoring are described as Non-invasive monitoring, ie without penetrating injections and Invasive monitoring, eg with arterial needle and CVL. More about monitoring is described elsewhere in the Anesthesia Guide.

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Anesthesia

Anesthesia for surgery can be divided into four different phases; induction, maintenance, awakening and recovery. The first three phases usually take place in an operating ward, while the recovery phase mainly takes place in a recovery ward, postoperative ward or intensive care unit. The control of an anesthesia through the different phases with different anesthetics is described here in the Anesthesia Guide. You will herein find several handouts with different variants of anesthetics for a balanced anesthesia.

Induction – anesthesia introduction

Induction, ie the onset of anesthesia, means putting the patient to sleep, or more correctly in a controlled stage of unconsciousness (anesthesia). Intravenous induction is standard for most anesthesiological procedures. Anesthesia is introduced by changed alertness in different stages of unconscioussness, different anesthesia depths at different speeds depending on the technology used. After the administration of anesthetics, one initially goes through a short stage of relaxation and disinhibition, then a short stage of excitation and then into the stage often referred to as surgical anesthesia with relaxation of muscle tone and decreased or ceased breathing with unresponsiveness to surgical stimuli. During induction, respiration, alertness, eye movements and coordination as well as pupil size, reflexes, muscle tone and other essential physiological functions are affected. It is important to try to go through the induction stage as smoothly as possible without a pronounced effect on heart rate and blood pressure. An attempt should be made to avoid a pronounced drop in blood pressure, but a mild drop in blood pressure is common and most patients who do not have significant cardiovascular disease tolerate this well. In the case of induction of fragile patients, it is advisable to co-administer a sympathomimetic agent or vasoconstrictor to avoid the antihypertensive effects of the anesthetics.

The induction usually starts with preoxygenation with oxygen via an anesthetic face mask with the patient in the “sniffing position” to prepare for taking control over the patient’s breathing and inserting a laryngeal mask or endotracheal tube. Once the patient is well oxygenated, it is started either by intravenous injection of anesthetic or by inhalation of a volatile inhalation anesthetic, an “anesthetic gas” such as sevoflurane. Intravenous induction is usually faster, more controlled and more predictable than initiation by mask via inhalation.

Induction by inhalation (“Mask anesthesia”)

Inhalation via inhalation of an anesthetic gas by mask is mostly used on children where you want to wait to insert an intravenous cannula (venous needle) until the child has fallen asleep and does not experience pain. This requires good knowledge of the effects of anesthetic gases and a good ability to handle the airway when the child falls asleep and goes through the various phases of the anesthesia initiation. During initiation on a mask, the excitation phase becomes stronger and more prolonged than during intravenous initiation. As a rule, one begins with spontaneous breathing to gradually switch to manually controlled breathing at the same time as the depth of anesthesia is deepened with inhalation anesthetics via carburetors. One should be careful but steady on the hand as strong manipulations of the airway during the excitation phase can trigger a laryngospasm which can complicate the onset of anesthesia and create difficulties in deepening the depth of anesthesia to the right level. The lowering of a pharyngeal tube can improve the airway and enable manual ventilation so that the excitation stage is passed properly while at the same time it can trigger a laryngospasm if done when the patient is too superficially anesthetized. The anesthetic gas must be administered at the right rate as too rapid administration can cause apnea or laryngospasm or trigger an anxious patient. Involuntary uncontrolled movements during this phase are common. Excessive excitation can cause severe stress with tachycardia and an increase in blood pressure followed by a sharp and dangerous drop in blood pressure when the excitation is passed and should therefore be avoided.

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Induction of anesthesia by inhalation with a face mask to adult patients is now rarely done but was more common in the past. This can be done in exceptional cases, e.g. of a patient with pronounced fear of venous cannulas or patient with severe autism. However, it is the undersigned’s personal experience that patients who are so pronouncedly afraid of stinging that they refuse intravenous initiation may also offer difficulties with initiation via inhalation. The best way to solve this problem is usually through good preoperative information and a strong premedication as well as effective topical anesthesia to be able to insert a needle into a vein. Another reason may be an extremely difficult-to-cannulate patient who has had enough of multiple stings in the awake state.

Intravenous induction

Intravenous induction with fast-acting anesthetics is standard in most anesthetics, both for children and adults. Anesthesia is prepared with a good premedication, if necessary topical anesthesia (skin anesthesia) and insertion of a venous cannula into a peripheral vein (“needle insertion”). After standardized preparation at the operating theatre and check-in, anesthesia starts with injections of fast-acting hypnotic agents that are either given manually in a peripheral venous cannula or via an infusion pump or in combination with manual injections and injection via an injection pump (syringe pump). In a traditional anesthetic, the drugs are given by hand via injection with a syringe. It is common to start with a strong opioid such as fentanyl or alfentanil for about two minutes. Then wait until it is noticed that the patient responds adequately to the given dose, which also verifies that the venous entrance works properly. In the next step, a dose of a hypnotic is given, usually propofol, but other agents can also be used such as pentothal, ketamine or etomidate. The dose is adjusted according to age, weight, condition and current state of the patient.

In normal anesthesia induction, muscle relaxants are given in the form of non-depolarizing agents when the patient “sleeps well” after the initiation, ie does not react with a blink reflex or when touched about 1-2 minutes after hypnotics are given. After muscle relaxants have been given, a “timer” is usually started and the patient is given controlled breathing through manual ventilation via a respirator and bag. This manual ventilation lasts for 90-120 seconds, after which intubation or insertion of the laryngeal mask can be performed. After the airway is secured, this is checked by auscultation with a stethoscope and control of the exhaled air with end-tidal carbon dioxide variation. After this, an anesthetic gas is usually switched on, for example sevoflurane or desflurane, and anesthesia passes into the next phase, the maintenance phase. The use of muscle relaxants is controlled according to whether it helps the surgeon, ie if it is necessary to be able to penetrate the abdomen or that the patient needs to lie completely still. Muscle relaxants may also be necessary to be able to ventilate the patient in the best way and coordinate with the surgery, for example during thoracoabdominal procedures.

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RSI induction

When anesthetizing a patient with an increased risk of respiratory aspiration of stomach contents, the patient is anesthetized with a so-called RSI technique: “Rapid Sequence Induction“. With this technology, the head end is placed in an elevated position, so-called “sniffing position”. The patient is carefully preoxygenated via spontaneous breathing on a tight-fitting mask with 100% oxygen, after which the induction agents are given in rapid succession with analgesics, hypnotics and muscle relaxants. Immediately after, the patient is intubated without controlled overpressure ventilation. You can also use cricoid pressure, but this has been questioned in recent years as it can complicate intubation and the benefits are doubtful. Examples of cases with an increased risk of aspiration are intestinal paralysis (ileus) and acute patients who have not fasted long enough.

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Vasopressor support in case of drop in blood pressure

Ephedrine: 5 mg/ml: (Direct receptor agonist + NA release -> α1 +, β1 +++, β2 ++ = SVR ↑, CO ↑, HR ↑, BT ↑)

  • Indication: Drop in blood pressure (bronchial asthma)
  • Dosage: 5-10 mg iv effect for 10-15 min (for longer lasting effect 25-50 mg can be given i m or s c)
  • Side effects: Tachycardia, arrhythmias, coronary ischemia

Phenylephrine: 0.1 mg/ml (or 0.2 mg/ml): (α1 ++++ = SVR CO, CO ↓, HR ↓, BT ↑)

  • Dosage: 0.1-0.2 mg iv, or by infusion 0.05-0.15 μg/kg/min iv = about 3 – 20 ml/h for 70 kg
  • Side effects: Bradycardia, heart failure, pulmonary edema

Noradrenaline: – α1 ++++, β1 +++, β2 + (SVR ↑, CO ± 0, HR ↑, BT ↑↑)

  • Indication: Sepsis, anaphylactic shock, hypotension with SVR ↓↓
  • Dosage: 0.01-0.5 ug/kg/min = 0.5-40 ml/h for 70 kg (0.1 mg/ml)

Maintenance phase

During the maintenance phase, anesthesia is controlled according to the principle of good homeostasis, where the anesthesia is adapted to the nature and extent of the procedure. Good continuous communication between the anesthesia personel and the surgeon is necessary for this to work out well. This is the phase where surgery is performed. Anesthesia is monitored and adjusted for heart rate, blood pressure, temperature, oxygen saturation, extracellular fluid volume, blood volume and cardiac output. Vigilance or the degree of unconsciousness is monitored clinically or with the help of anesthesia depth gauges such as BIS or Entropy, a value between 40 and 60% is normally sought and one tries to avoid too shallow or too deep sleep.

  • What is monitored during Anesthesia? | Anesthesia Information and Emergency Medicine

Anesthesia is maintained with either intermittent doses of intravenous agents such as fentanyl in combination with an inhaled anesthetic such as sevoflurane, or with a continuous infusion of an opioid in combination with an inhaled anesthetic or with intravenous agents alone, eg propofol and remifentanil. If only intravenous drugs are used, the anesthesia method is called Total Intravenous Anesthesia (TIVA), while the combined technique with inhaled anesthetics is called Balanced Anesthesia. Which technique is preferred can be controlled by the anesthesiologist and is often based on the nature of the procedure as well as local routines and practices. Some prefer an inhalation controlled technique while others prefer the intravenous technique and still others prefer the combined technique. Both techniques are well-proven and well-functioning. The degree of administration of anesthetic is controlled by the surgery and by the patient’s alertness and physiological condition. Anesthesia is always a dynamic condition with continuous variations that make it an exciting and challenging job. Changes in physiology and settings in anesthesia are continuously recorded in the so-called the anesthesia chart. The anesthesia chart has in all years been a paper journal that is written continuously by the anesthesia nurse throughout the procedure from start to finish, but in recent years more and more information has been digitized and some clinics only use digital systems. As the operation or intervention under anesthesia approaches the end, anesthesia is adjusted accordingly, the anesthetics are down-regulated and one enters the next phase, the awakening phase.

Awakening

Towards the end of the surgical procedure, anesthesia is adjusted after the patient is to be awakened from the anesthesia. The anesthetics are reduced so that the effect decreases and the patient rises in wakefulness. This is adapted to the surgery, the patient should generally be well anesthetized until the last stitch is set, or alternatively until the patient is turned in the correct position for awakening, eg from abdominal position to back position. The surgical wound should be closed and bandages should be applied before awakening. All sterile surgical clothing must be removed in a “unwrapping” and an “uncover” of the patient, which usually goes relatively quickly. Injections, any wound drains and drips must be adjusted and adapted to the postoperative phase. Patients without bladder catheters should usually undergo a so-called “Bladder scan” where the volume of urine is measured and possibly removed before awakening from anesthesia. The patient should then be extubated or the laryngeal mask removed and this happens when the patient wakes up and can manage their own spontaneous breathing in a reassuring way.

Criteria for extubation

  • Eye opening
  • Facial grimace
  • Patient movement other than coughing
  • Conjugate gaze
  • Purposeful movements
  • End tidal anesthetic less than:
    • Sevoflurane: 0.2%
    • Isoflurane: 0.15%
    • Desflurane: 1.0%
  • Oxygen saturation greater than 97%
  • Positive laryngeal stimulation test
  • Tidal volume greater than 5 ml/kg

The awakening itself usually takes place by switching off the anesthetics and the patient wakes up by himself when the sedative effects subside. The closure of anesthetics and dilution of anesthetic gases are adjusted by the end of the operation. The patient usually wakes up when spontaneous breathing is stable and the MAC value of the gas is down to 0.1% (see above). Alternatively, certain antidotes can be given, such as naloxone to break the opioid effect, but antidotes are used restrictively to avoid breakthrough pain. Instead, a slightly more long-acting analgesic is usually given, such as morphine towards the end of the operation so that the patient is pain-free when he wakes up from the anesthesia. Patients who have been anesthetized with only intravenous technology usually wake up faster and better compared to patients who have received inhaled anesthetics.

Reversal of the muscle relaxing effects is routinely done towards the end of anesthesia after clinical assessment or after measurement of muscle activity by TOF measurement, e.g. see special chapter in the Anesthesia Guide on muscle relaxants. Muscle relaxants are usually reversed by giving a cholinesterase inhibitor such as neostigmine in combination with an anticholinergic (Atropine/Neostigmine). Alternatively, the antidote sugammadex can be used. The patient is not extubated until it has been ascertained that adequate muscle strength has returned and muscle relaxation has been reversed, for example that the patient can squeeze the hand with a firm grip or lift the head from the pillow and above all maintain good breathing. Insufficient muscle activity can look like shallow jerky breathing which has been described as “a fish on dry land” which is a potentially life-threatening condition.

When the patient wakes up, the person in question is extubated, ie the endotracheal tube or laryngeal mask is removed and the pharynx is cleansed of mucus. This is done in a controlled manner when the patient can breathe satisfactorily and can look up and make eye contact. If the patient is worried about irregular breathing, cannot make eye contact or has obvious respiratory irritation (apnea), it may be worthwhile to give a small dose of propofol 20-40 mg to relax the patient and be able to eliminate more anesthetic gases that improve the conditions for extubation. Respiratory, the patient should be able to breathe with a maximum of 5 cm PEEP and 35% oxygen in order to be extubated safely. After extubation, the patient should be able to cope with their own spontaneous breathing and maintain a free airway even in the supine position. Oxygen is usually given on a halter or respirator during the recovery phase.

After surgery on very fragile patients or after major procedures or in case of respiratory problems, the endotracheal tube is often maintained and the patient is admitted to intensive care or postoperative care, still connected to a ventilator for a later extubation in a more stable condition. If you are unsure whether the patient can cope with an extubation, it is better to maintain the tube until a later stage, for example if the patient has become hypothermic, is circulatory unstable or in case of large or ongoing bleeding. The transfer of the patient then usually takes place with a so-called transport ventilator in to the recovery room or ICU.

The awakening phase

When the patient is awakened from the anesthesia and the operation is completed, the patient should be transferred to a recovery ward or a postoperative ward under stable conditions. As a rule, the extubation takes place in the operating room on the operating table and the patient is then transferred to his bed, but in some cases the patient is first transferred to the bed and then extubated there. This occurs, for example, when the movement can be expected to be painful or when it is important to avoid uncontrolled movements. Conversely, certain anesthetics are initiated in bed instead of on the operating table when the movement is expected to be painful, for example in acute fractures.

The awakening is usually handled by staff other than anesthesia staff in a postoperative ward. The time at the recovery ward is determined by the nature of the procedure and the patient’s condition. Large surgeries naturally require longer postoperative periods, but this varies from case to case. In the postoperative ward, it is important to continue good monitoring of vital functions such as breathing, pulse and blood pressure. Postop usually has a large number of patients at the same time and it is important that everyone is well monitored and that any complications are detected in time and remedied quickly. Examples of serious complications can be, for example, apnea or respiratory failure, bleeding or a marked drop in blood pressure. Recommended times for postoperative monitoring can be found elsewhere in the anesthesia guide.

In the recovery phase, it is important that the patient wakes up in a reassuring way with adequate pain relief. This is given either intravenously or in the form of blockades with local anesthetics. Many patients present with an epidural anesthesia (EDA) that has either been started or should be started postoperatively. Any antibiotic prophylaxis should be given as well as thrombosis prophylaxis at the right time. Any wound drains and ventricular drains must be checked for functioning and uncontrolled bleeding must be detected in time. Any X-ray examinations may need to be performed. Adjustments of antihypertensive and inotropic agents such as norepinephrine infusion are made continuously. Measurement of hourly diuresis is done in relevant cases. Nausea may need to be prevented and treated with antiemetics (PONV). Blood gases and laboratory parameters may need to be monitored and checked.

Patients who have undergone major surgery or are unstable after surgery are often brought up in the postoperative ward. The extubation here is similar to surgery, but the patient is usually no longer affected by inhalants. Body temperature should be above 36 degrees and arterial blood gases are often monitored. After completing the recovery phase, the patient can be transferred to a surgical ward for continued care and treatment or if it is a matter of day surgery being discharged to the home. Before returning home, special routines apply for this to work in a safe and secure manner.


Induction of anaesthesia

Intravenous induction agents

Propofol

  • Concentration: 5 mg/ml, 10 mg/ml, 20 mg/ml
  • Induction dose for anesthesia: 2 mg/kg (child – 2.5-3.5 mg/kg)
  • Sedation bolus: 0.5 mg/kg
  • Maintenance anesthesia: 4-10 mg/kg/h in decreasing dose, TCI 2-6 ug/ml, Sedation: 0.5-4 mg/kg/h
  • Avoid: Sedation at ICU < 16 years

Thiopenthone (Sodium thiopental)

  • Concentration: 25 mg/ml
  • Induction dose for anesthesia: 4-6 mg/kg (70 kg -14 ml)
  • Avoid: porphyria, upper respiratory tract obstruction, asthma attacks, extravasal & intrarterial injection

Ketamine (Ketalar)

  • Concentration: 10 mg/ml iv, 50 mg/ml im
  • Induction dose for anesthesia: 1-2 mg/kg iv, (5) -10 mg/kg im + midazolam 1-3 mg (silent on the floor)
  • Maintenance anesthesia: 0.5-4 mg/kg/h iv in decreasing dosage
  • Post-op pain relief: 5-15 mg bolus,
  • Maintenance infusion: 0.05-0.5 mg/kg/h
  • Avoid: Hypertension (relative contraindication).
  • In case of liver failure -> dose reduction
  • Esketamine (Ketanest): 5 mg/ml iv, 25 mg/ml im => half the ketamine dose

Pocket Guide Anesthesia

Edited by Patrik Martner, Specialist Physician in Anesthesia & Intensive Care. Sahlgrenska University Hospital.

Updated 2020-10-02


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Propofol

Propofol is a substituted phenol which, when administered intravenously, provides general anesthesia.

Propofol is a short-acting intravenous anesthetic for the induction and maintenance of general anesthesia in adults and children over 1 month of age. Propofol is also used for sedation in diagnostic and surgical procedures, in adults and children over 1 month. Propofol is used for sedation of ventilated patients over 16 years of age in the intensive care unit.

Propofol (2,6-diisopropylphenol) is a substituted phenol that gives anesthesia when administered intravenously. The mechanism of action of propofol is not fully known, but the effect is probably exerted via a non-specific membrane binding of the substance in alertness-regulating neurons in the brain, mainly in the thalamus. Intravenous administration of propofol provides rapid anesthesia, within about 30 seconds, and the effect lasts about 5-10 minutes. The awakening is relatively fast.

Concentration: 5 mg/ml, 10 mg/ml or 20 mg/ml. For anesthesia in adults, 10 mg/ml is usually used. For sedation on IVA, 20 mg/ml is usually used. For children, 5 mg/ml is recommended for manual induction.

Dosage: The usual dose for induction of anesthesia is 1.5-2.5 mg/kg intravenously at a rate of 40 mg/10 sec until anesthesia occurs. In patients with complicated diseases (ASA 3 and 4), anesthesia should be induced more slowly, 20 mg/10 sec. Patients over the age of 55 may require a lower induction dose. The total dose can be reduced if the induction dose is given at a lower rate (20-50 mg/min). Depending on the injection rate, the time to induce anesthesia is between 30 and 40 seconds. After a bolus injection, the effect is short-lived due to the rapid metabolism and excretion (4-6 min).

TIVA dosage

  • Intubation dose: 10-14 mg/kg/h
  • Maintenance dose for superficial surgery: 6-12 mg/kg/h
  • Maintenance dose for deep surgery: 14-16 mg/kg/h
  • Induction 1-2-3 mg/kg over 45 sec

TCI dosage

  • Intubation dose: 4-6 μg/ml
  • Maintenance dose for superficial surgery: 2-4 μg/ml
  • Maintenance dose for deep surgery: 4-6 μg/ml

Propofol is widely distributed and rapidly eliminated from the body (total body clearance: 1.5–2 liters/minute). The elimination takes place through metabolic processes, mainly in the liver where it is dependent on blood flow, whereby inactive conjugates of propofol and the corresponding quinol are formed, which are excreted in the urine.

Propofol 20 mg/ml is not recommended for general anesthesia in children under 3 years of age as it is difficult to set the correct dose of strength 20 mg/ml as treatment of young children requires extremely small volumes. For children between 1 month and 3 years, when a dose lower than 100 mg/hour is needed, Propofol 10 mg/ml is recommended instead as an infusion.

Administration of Propofol with TCI (Target Controlled Infusion) systems is not recommended for use in children < 16 years of age.

Warning:

A few reports have been received in adult patients suffering from metabolic acidosis, rhabdomyolysis, hyperkalaemia and / or rapidly increasing heart failure (in some cases fatal) after being sedated for more than 58 hours at doses above 5 mg/kg/hour, the so called Propofol infusion syndrome.


Thiopenthone (Sodium thiopental)

Ultra short-acting intravenous barbiturate anesthetic agent. Thiopenthone induces sleep given intravenously. It induces hypnosis and anesthesia, but not analgesia. Used primarily for induction of anesthesia for surgery but also for short-term medical procedures where short-term sleep is sought. Usually given by manual injection with a syringe (25 mg/ml) where the rate and dose are adjusted according to the patient’s condition and the nature of the procedure. Thiopenthone can be given as a continuous infusion in the treatment of status epilepticus and increased intracranial pressure in cerebral edema. Thiopenthone was for several decades the standard drug for anesthesia induction but has in recent years been replaced by propofol and other anesthetics. It causes a dose-dependent depression of breathing and circulation. Thiopenthone is only a hypnotic and not an actual analgesic, but pain relief to some extent accompanies the depth of the anesthesia. For surgical anesthesia, therefore, thiopenthone is usually supplemented with strong opioids such as fentanyl in a balanced anesthesia. Compared with propofol, thiopenthone does not provide the same relaxation in the upper respiratory tract, which can lead to some rigidity and difficulties with manual ventilation. A small dose of thiopenthone can be given to prevent or treat laryngospasm in children.

Concentration: 25 mg/ml.

Pentothal is delivered and stored as a dry substance and is usually diluted to a daily fresh concentration of 25 mg/ml. Diluted solution only has a shelf life of 24 hours and should be stored in a refrigerator.

Dosage

Induction anesthesia: 4-6 mg/kg. Normal dose: 70 kg: 14 ml (± 4 ml) = 350 mg. A normal induction dose for adults is 4-6 mg/kg body weight, but the individual response is so variable that no fixed dose can be indicated. Usually between 200 and 400 mg is given as an induction dose (8 – 16 ml at 25 mg/ml), default 14 ml. In patients with poor general condition, the dose should usually be reduced and carefully titrated. Following intravenous administration, unconsciousness occurs within 30 seconds and persists for 20-30 minutes after a single dose. Rapid uptake occurs in most vascular areas of the brain, followed by redistribution to other tissues. It is rarely justified to give more than 500 mg intravenously. After an intravenous single dose, thiopental has a distribution half-life of 2-4 hours and for elimination the half-life is 9-11 hours. Plasma protein binding is 80-90% at therapeutic concentration.

Avoid

Porphyria, upper respiratory tract obstruction, asthma attacks, extravascular and intrarterial injection.

Caution

Caution in case of severe obesity, hypovolemia, hypotension or severe shock. It may release histamin with a transient flush in skin after delivery.

Brand name

Pentocur, Thiopental (deregistered)


Fentanyl

Intravenous short-acting anesthetic agent and analgesic. Fentanyl is intended for use in anaesthesia for surgical procedures and for sedation in painful or stressful medical procedures. Fentanyl is a selective μ-opioid agonist with rapid onset and  short duration of action. Despite rapid onset of action, the maximum analgesic and respiratory depressant effect is achieved only after a few minutes. Normally, the analgesic effect of an intravenous injection of 100 micrograms of fentanyl lasts about 30 minutes. In pharmacodynamic terms, fentanyl reminds of morphine but has more potent analgesic and respiratory depressant effect.  Even in large bolus doses, fentanyl has often been used for induction of anesthesia in patients with heart disease, owing to its cardiac stability and its ability to blunt hemodynamic responses to tracheal intubation.

Plasma protein binding is 80-85%. Fentanyl is not plasma cell bound and plasma protein binding is affected to a small extent by pH. Fentanyl is metabolised in the liver to inactive metabolites.

The plasma concentration of fentanyl decreases rapidly after an i.v. injection. The elimination process of fentanyl is triphasic with half-lives of approximately 1 minute, 15 minutes and 6 hours. The distribution volume in the central compartment is approximately 15 liters and the total distribution volume is approximately 400 liters. Secondary peaks in plasma levels may occur. Approximately 75% of the dose is eliminated within 72 hours.

Dosage

In anesthesia procedures, the usual initial dose of fentanyl to adults is 50-100-200 μg, 1-2 -4 ml, which is slowly injected intravenously. The dose may be repeated 20-30-45 minutes after the initial dose. Secondary respiratory depression has been observed in cases where large doses were accumulated.

Fentanyl should be used with caution in uncompensated hypothyroidism, lung disease, especially such as lowering lung capacity, alcohol abuse, liver or renal insufficiency. Tolerance and addiction can be induced. Fentanyl reduces the need for hypnosis necessary to maintain anesthesia, so the dose of hypnotic or volatile anesthetics should be reduced.

  • Intubation dose for general anesthesia: 1–8 μg/kg i.v. (70 kg = 70-600 μg = 2 – 12 ml).
  • For children 2 – 12 years, 1 – 3 μg/kg are given in combination with inhalation anesthesia.

Maintenance dose for sedation at ICU:

  • Adults 0.5-2 μg/kg/hour
  • Children: 0.5-1 μg/kg/hour
  • Standard dose: 0.5 μg/kg/h

In ventilated patients, a loading dose of fentanyl may be given as a rapid infusion of approximately 1 μg/kg/minute for the first 10 minutes followed by an infusion of approximately 0.5 μg/kg/h. Alternatively, the loading dose of fentanyl may be given as a bolus dose. The infusion rate should be titrated according to individual patient response; lower infusion rates may be sufficient.

TIVA dose

Maintenance dose for surgical anesthesia: 0.1-0.70 μg/kg/min. Default dose: 0.15 μg/kg/min. Intubation bolus dose: 1-2 μg/kg.

Fentanyl can be given as an infusion. In ventilated patients, a loading dose of fentanyl may be given as a rapid infusion of approximately 1 μg/kg/minute for the first 10 minutes followed by an infusion of approximately 0.1 μg/kg/minute. Alternatively, the loading dose of fentanyl can be given as a bolus dose. The infusion rate should be titrated according to individual patient response; lower infusion rates may be sufficient.

TCI dose (Insufficient data)

Fentanyl is normally not given in the TCI mode but rather in the TIVA mode or in boluses intermittently. Maintenance target concentration for surgical anesthesia is unknown: (1-4 ng/ml ?). Default concentration is unknown (2 ng/ml ?) (Cpt).

Induction: 100 μg (2 ml) is given for 10 sec.

Concentration

Solution 50 μg/ml.

Strength

Approximately about 100 times the potency of morphine. (1 ml fentanyl ≈ 10 mg morphine).

Side effects

May cause respiratory failure and respiratory depression. May give muscle rigidity especially at high doses and difficulty in ventilating the patient manually. It can cause somnolence and increased fatigue. May cause bradycardia and hypotension. Muscle rigidity has been observed in increased frequency at high doses and on rapid administration of fentanyl. Bradycardia and possibly asystole may occur if the patient is given an insufficient dose of anticholinergics or if fentanyl is combined with non-vagolytic muscle relaxants. Secondary respiratory depression has been observed rarely.

Warning

Fentanyl reduces the need for hypnosis necessary to maintain anesthesia, so the dose of hypnotic should be reduced. Since adverse hemodynamic effects of fentanyl are more pronounced and frequent in patients with ASA III-IV than with longer-acting opiates, great caution should be observed when administering fentanyl to this patient population.


Ketamine

Anesthetics for intravenous or intramuscular administration for induction of anesthesia and maintenance. Can also be given orally for sedation. Induction and maintenance of anesthesia in diagnostic and surgical procedures, as the sole anesthetic or in combination with other anesthetics. Ketamine can be given before or as a complement to regional anesthesia, even in acute fracture surgery. Ketamine or ketanest can be given as a continuous infusion in the treatment of severe pain alone or in addition to other pain treatment. Ketamine has been described as having a fast-acting antidepressant effect and is now being tested in depression and in severe pain conditions. (For this purpose, ketamine can be given in a nasal spray).

  • Ketalar = Ketamine in racemic form (50% Ketamine-R + 50% Ketamine-S)
  • Ketanest = Ketamine-S = Esketamine. Ketanest is about twice as potent as Ketalar and has less cognitive impact.

Ketamine is an NMDA receptor blocker and provides a so-called dissociative anesthesia with effective pain relief through selective disruption of association pathways in the brain. The patient falls asleep easily after induction and is placed in a hypnotic state where pain or perception (other sensory impressions) is no longer experienced normally. The condition is dreamlike and often vivid dreams of a hallucinatory nature are described. Dreams can be both pleasant and unpleasant. The patient has increased sensitivity to sound, which is why the environment should be calm, quiet and peaceful. The depth of the anesthesia can be difficult to assess as the patient no longer reacts to sound, light, touch or speech without being apparently asleep. In subanesthetic doses, ketamine has an analgesic effect that is likely due to interaction with biogenic amine and endogenous opiate systems. Ketamine usually does not affect the reflexes of the pharynx and larynx and muscle tone remains normal or increases slightly. Cardiovascular and respiratory stimulating effects allow ketamine to be given to high-risk patients in hypovolemic shock. The analgesic effect can be used as a complement to regional anesthesia or in mass injury situations/disaster contexts.

Concentration

10 mg/ml for intravenous use, 50 mg/ml for intramuscular use.

Induction anesthesia

1-2 mg/kg iv, alternatively (5) -10 mg/kg im (+ midazolam 1-3 mg). An intravenous dose of 2.0 mg/kg body weight provides surgical anesthesia within one minute after injection and the anesthetic effect lasts for 5-15 minutes. Intramuscular dosing 10.0 mg/kg body weight provides surgical anesthesia within 3-5 minutes after injection with a duration of 12-25 minutes. To achieve prolonged anesthesia or analgesia, ketamine can be given by infusion (0.5-4 mg/kg/h) or syringe pump for even administration, for example during anesthesia of a patient in bleeding shock. The onset of anesthesia is accompanied by temporary tachycardia, increase in blood pressure and cardiac output, which return to baseline within 15 minutes after injection. (Preferably quiet in the ward or headphones on the patient). Orally, Ketamine provides good sedation after 10-15 minutes and be about 30-45 minutes. It can be diluted in juice at a dose of about 4-5 mg/kg.

Maintenance dose anesthesia

  • 0.5-4 mg/kg/h iv in decreasing dosage
  • Postoperative pain relief: 5-15 mg bolus
  • Maintenance infusion for postoperative pain relief: 0.05-0.5 mg/kg/h

Caution:

Hypertension (relative contraindication). In case of liver failure, the dose should be reduced. There is a risk of abuse with non-medical use.


Alfentanil

Intravenous ultra-short acting anesthetic agent and analgesic. Alfentanil is intended for use in pain relief in short and medium surgical procedures. Alfentanil is a selective μ-opioid agonist with rapid onset and very short duration of action. Maximum effect is reached within 90 seconds with an effect duration of 5-10 minutes. Alfentanil is chemically related to fentanyl. In pharmacodynamic terms, alfentanil reminds of morphine but has more potent analgesic and respiratory depressant effect.

The distribution volume is 0.4-1.0 l/kg. Plasma protein binding is 92%. Alfentanil is not plasma cell bound and plasma protein binding is affected to a small extent by pH. Alfentanil is metabolised in the liver to inactive metabolites.

Dosage

In case of a short procedure: 0.25-0.5 mg i v – repeat when needed. Optimal intubation dose: 20-40 μg/kg iv (70 kg = 1.5-3 mg = 3-6 ml). Estimated operating time 10-30 minutes: 20-40 μg/kg, intravenous bolus dose in 3-6 ml/70 kg. Estimated operating time 30-60 minutes: 40-80 μg/kg, intravenous bolus dose in 6-12 ml/70 kg.

TIVA dose

Maintenance dose for surgical anesthesia: 0.20-0.70 μg/kg/min, Default dose: 0.35 μg/kg/min. Intubation dose: 0.70 μg/kg/min.

TCI dose

Maintenance dose for surgical anesthesia: 40-70 ng/ml, Default concentration 50 ng/ml (Cpt). Induction: 109 μg (0.218 ml) is given for 10 sec.

Concentration

Solution at 0.5 mg/ml.

Strength

Approximately 25 times the potency of morphine (1 ml Alfentanil ≈ 12.5 mg morphine).

Side effects

May cause respiratory failure and respiratory depression. May give muscle rigidity especially at high doses and difficulty in ventilating the patient manually. It can cause somnolence and increased fatigue. May cause bradycardia and hypotension. Muscle rigidity has been observed in increased frequency at high doses and on rapid administration of alfentanil. Bradycardia and possibly asystole may occur if the patient is given an insufficient dose of anticholinergics or if alfentanil is combined with non-vagolytic muscle relaxants. Secondary respiratory depression has been observed rarely.

Warning

Alfentanil reduces the need for hypnosis necessary to maintain anesthesia, so the dose of hypnotic should be reduced. Since adverse hemodynamic effects of alfentanil are more pronounced and frequent in patients with ASA III-IV than with longer-acting opiates, great caution should be observed when administering Alfentanil to this patient population.


Remifentanil

Intravenous ultra short acting anesthetic agent. Remifentanil is a selective μ-opioid agonist with rapid onset and very short duration of action. Remifentanil is a so-called esterase metabolized opioid, which is metabolized by non-specific blood and tissue esterases.

Solution at 50 μg/ml. Recommended dilution for general anesthesia is 50 μg/ml for adults and 20 μg/ml for children ≥ 1 year.

Indication

Used as analgesic in induction and/or maintenance of general anesthesia under assisted breathing in surgical procedures including anesthesia in cardiac surgery. For pain relief and sedation in intensive care of mechanically ventilated patients 18 years of age and older.

Dosage

Intubation dose TIVA 0.25-0.5 μg/kg/min, TCI 6-8-(12) ng/ml. Maintenance dose during light surgery TIVA 0.15-0.25 μg/kg/min, TCI 4-6 ng/ml. Maintenance for major surgery TIVA 0.2-0.5 μg/kg/min, TCI 5-10 ng/ml. 0.5 μg/kg/min can be given as induction dose in TIVA up to 100-150 μg.

Following administration of recommended doses of remifentanil, the effective half-life is 3-10 minutes. The mean clearance of remifentanil in young healthy adults 40 ml/min/kg, central volume of distribution 100 ml/kg and steady state volume of distribution 350 ml/kg.

Remifentanil reduces the need for hypnosis necessary to maintain anesthesia, so the dose of hypnotic should be reduced. Since adverse hemodynamic effects of remifentanil are more pronounced and frequent in patients with ASA III-IV than with longer-acting opiates, great caution should be observed when administering Remifentanil to this patient population.


Esketamin (Ketanest)

Esketamine in low dose for pain treatment

Ketamine (S and R, see below), which is an NMDA receptor blocker, modulates both surgically induced and drug-induced hyperalgesia at doses much lower than the doses required for general anesthesia. (Hyperalgesia = increased response in a painful direction.) Ketamine has an opioid-saving effect.

There are two isomers: Ketamine-S and Ketamine-R.

  • Ketanest = Ketamine-S = Esketamine. Ketanest is about twice as potent as Ketalar and produces less cognitive impact.
  • Ketalar = Ketamine in racemic form (50% Ketamine-R + 50% Ketamine-S).

Indications

  • Expected postoperative pain problem
  • Amputation (upper, lower extremity)
  • Acute phantom pain
  • Patients with long-term pain + acute pain
  • Ongoing high opioid medication (opioid tolerant patient) + acute pain
  • Abuse in the history (when avoiding opioids) + acute pain

Dosage Perioperative

Ketanest Infusion; low-dose infusion (in addition to local, regional or general anesthesia)

  • Start of operation: 0.1 – 0.3 mg/kg bolus iv
  • Maintenance dose: 0.1 – 0.3 mg/kg/h iv
  • After the last suture is set: 0.03 mg/kg/h iv
  • Postoperatively for 12 – 72 hours: 0.03 – 0.06 mg/kg/h intravenously. 

Postoperatively inserted Ketanest or Ketanest for unoperated patients

  • Single bolus doses: 0.1 mg/kg iv
  • And/or low dose infusion:
    • Loading dose (bolus dose): 0.1 mg/kg iv
    • Maintenance dose: 0.03 – 0.06 mg/kg/h iv, given over 12 – 72 hours.

Ketamin infusion dosing schedule

Infusion rate in ml/h at different body weights
 
Patient's Weight (kg):40 kg 50 kg 60 kg 70 kg 80 kg 90 kg 100 kg 110 kg
Ketanest dosage (mg/kg/h)
0,03 mg/kg/h: 1.21.51.82.12.42.733.3
0,04 mg/kg/h 1.622.42.83.23.644.4
0,05 mg/kg/h 22.533.544.555.5
0,06 mg/kg/h 2.433.64.24.85.466.6
0,1 mg/kg/h 4567891011
0,2 mg/kg/h 810121416182022
0,3 mg/kg/h 1215182124273033
NOTE! Ketanest and barbiturates (eg Tiopental) should not be administered in the same entry (chemically incompatible).
Dilution: 2 ml Ketanest 25 mg/ml + 48 ml NaCl 9 mg/ml = giving 50 ml Ketanest 1 mg/ml. [Infusion is given iv with pump (50 ml syringe). Shelf life after mixing: not more than 12 hours.]

Drug combinations and recommendations

  • Ketanest is preferably combined with low dose midazolam, or other benzodiazepine.
  • Increased salivation is common during treatment with Ketanest; – give Glycopyrronium (Robinul) or Atropin iv.
  • There are no significant interactions when Ketanest is given in low dose, which means that other prescribed analgesics (paracetamol, NSAIDs, Cox-2 inhibitors, opioids, clonidine, gabapentin, pregabalin, local anesthetics) should be given.
  • Ketanest should not be mixed with morphine in the same iv-PCA pump.
  • Ketanest is not recommended as iv-PCA.
  • The seizure threshold may be reduced in combination with xanthine derivatives (for example, aminophylline and theophylline) and therefore these combinations should be avoided.
  • The medicine should not be used with Ergometrine (Ergotamine).

Monitoring and documentation

  • Patients with IV low dose infusion Ketanest are usually monitored at the department of postop/ICU.
  • Document sedation rate, RASS/VAS, respiratory rate, SaO2, heart rate and blood pressure.
  • Ask for nightmares, hallucinations and vision disorders in connection with monitoring.

Side effects

  • Nightmares, hallucinations or visual disturbances appear to be insignificant in low dose infusion and/or in single bolus. Give 1 – 3 mg midazolam iv (or other benzodiazepine) as needed.
  • Increased salivation. Give glycopyrronium (Robinul) or atropine iv.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients.
  • Eclampsia and pre-eclampsia.
  • Patients in whom an increase in intracranial pressure is a serious risk.
  • Patients in whom an increase in blood pressure is a serious risk.

Warnings and Caution

  • Tachyarrhythmias
  • Untreated hypertension
  • Increased intracranial pressure, head injury or hydrocephalus
  • Increased intraocular pressure (eg, glaucoma) or eyeball damage
  • Alcohol intoxication
  • Psychiatric history (eg schizophrenia and acute psychosis)
  • Hyperthyroidism
  • Acute intermittent porphyria

References

  1. FASS 2017
  2. Christensen KF, Brandsborg B, Nikolajsen L: Perioperative ketamine for the treatment of acute postoperative pain. Expert Opinion. J of Sympt and Signs, 2013; 2: 398-402
  3. McCormick Z, Chang-Chien G, Marshall B, Huang M, Harden RN: Phantom limb pain: a systematic neuroanatomical-based review of pharmacologic treatment. Pain Medicine 2014; 15: 292-305
  4. The Chef MF, Lavand’homme PM: The clinical role of NMDA receptor antagonists for the treatment of postoperative pain. Best Pract Research Clin Anaesthesiol, 2007; 21 (1): 85-98
  5. Suzuki M: Role or N-methyl-d-aspartate receptor antagonists in postoperative pain management. Current Opinion in Anaesthesiology, 2009; 22 (5): 618-22
  6. Hocking G, Visser EJ, Schug SA, Cousins ​​MJ. Ketamine: Does Life Begin at 40? Pain: Clin Updates 2007; XV (3): 1-6
  7. Bell RF, Dahl JB, Moore RA, Kalso E: Peri-operative ketamine for acute post-operative pain: a quantitative and qualitative systematic review. Acta Anaesthesiol Scand, 2005; 49: 1405-28
  8. Loftus RW, Yeager MP, Clark JA, Brown JR, Abdu WA, Sengupta DK, Beach ML. Intraoperative ketamine reduces perioperative opiate consumption in opiate-dependent patients with chronic back pain undergoing back surgery. Anesthesiol, 2010; 113: 639-46
  9. Hadi BA, Al Ramadani R, Daas R, Naylor I, Zelko R: Remifentanil in combination with ketamine versus remifentanil in spinal fusion surgery – a double blind study. Int J Clin Pharmacol Ther. 2010: 48 (8): 542-8
  10. Hang LH, Shao DH, Gu YP: The ED50 and ED95 or ketamine for prevention of postoperative hyperalgesia after remifentanil-based anesthesia in patients undergoing laparoscopic cholecystectomy. Swiss Med Weekly, 2011; 141: w13195
  11. Sveticic G, Farzanegan F, Zmoos P, Zmoos S, Eichenberger U, Curatolo M: Is the combination of morphine with ketamine better than morphine alone for postoperative intravenous patient-controlled analgesia? Anaesth Analg, 2008; 106 (1): 287-93

Sevofluran (Sevorane®, Sevofluran®)

Sevoflurane is a halogenated methyl isopropyl ether. It is an inhalation anaesthetic agent used for induction and maintenance of general anesthesia. Sevoflurane is administered after vaporization, by laryngeal mask or endotracheal intubation.

Indication

Induction and maintenance of general anesthesia. Changes in the clinical effects of sevoflurane follow rapid changes in inhaled concentration. Like all inhaled anaesthetics, sevoflurane provide a controlled degree of unconsciousness and analgesia (anesthesia) and, in addition, reduces cardiovascular function in a dose-related manner. The low solubility of sevoflurane in blood causes the alveolar concentration to rapidly increase upon induction and rapidly decreases upon discontinuation of the inhalation anaesthetic agent. The blood/gas solubility coefficient is 0.68 for sevoflurane.

Dosage

Surgical anesthesia can be maintained at a concentration of 0.5 – 3% with or without simultaneous administration of nitrous oxide. Normally, a MAC value is sought between 0.8 and 1.6, usually 1.2-1.4. As with other halogenated volatile anaesthetics, the MAC for sevoflurane decreases when given in combination with nitrous oxide. The MAC value for sevoflurane decreases by 25-50% for adults and about 25% for children when 60-65% nitrous oxide is given at the same time. As with other inhalation anaesthetics, elderly patients usually require lower concentrations of sevoflurane to maintain surgical anesthesia. In humans, < 5% of absorbed sevoflurane is metabolized in the liver to hexafluoroisopropanol (HFIP) with the release of inorganic fluorine and carbon dioxide. HFIP is then conjugated rapidly with glucuronic acid and excreted in the urine. The fast and extensive lung elimination of sevoflurane minimizes the amount available for metabolism.

Recovery

Recovery is generally rapid after sevoflurane anesthesia with awakening within 5-30 minutes. Patients may therefore need postoperative pain relief early.

Caution

Sevoflurane may trigger malignant hyperthermia in predisposed patients. Caution in severe renal impairment or greatly increased intracranial pressure.


Desfluran (Suprane®)

Desflurane is a halogenated methyl ethyl ether (difluoromethyl-1,2,2,2-tetrafluoroethyl ether). It is an inhalation anaesthetic agent used for the maintenance of general anesthesia via the respiratory tract. It is supplied in the respiratory tract after gasification, via laryngeal mask or an endotracheal tube.

Indication

Induction and maintenance of general anesthesia. Changes in the clinical effects of desflurane follow rapid changes in inhaled concentration. Like all inhalation anaesthetics, desflurane delivers a controlled degree of unconsciousness and analgesia (anesthesia), and desflurane also decreases the cardiovascular function in a dose-related manner. Desflurane should not be used for anesthesia induction in children due to the high incidence of coughing, respiratory arrest, apnea, laryngospasm and increased secretion of the sebum. The blood/gas solubility coefficient is 0.42 for desflurane. The low solubility of desflurane in blood causes the alveolar concentration to rapidly increase upon induction and rapidly decreases upon discontinuation of the inhalation anaesthetic agent. Desflurane provide a dose-dependent reduction of blood pressure and breathing..

Dosage

Surgical anesthesia can be maintained at a concentration of 2.5-8% with or without simultaneous use of nitrous oxide. Usually 4-6% of desflurane is given in the inspiratory air. Normally, a MAC value is aimed at between 0.8 and 1.6, usually 1.2-1.4. In adults, surgical anaesthetic depth can be maintained with a reduced concentration of desflurane when nitrous oxide is used simultaneously. Higher concentrations of desflurane may be indicated. However, one should take into account the risk of hypoxia and adjust nitrous oxide/oxygen supply. The maintenance dose should be adjusted gradually in relation to the clinical effect. Desflurane is indicated for maintenance anesthesia to in neonates and children. Surgical anaesthetic depth can be maintained in children with end-tidal concentrations of 5.2 to 10% desflurane with or without simultaneous use of nitrous oxide. Studies have shown that only 0.02% of the absorbed desflurane is metabolized. Only marginal increases in inorganic fluoride can be seen in serum and urine. The rapid and extensive lung elimination of desflurane minimizes the amount available for metabolism. Generally, awakening is rapid after desflurane anesthesia for 5-30 minutes. Patients may therefore need postoperative pain relief early.

Recovery

Recovery is generally very rapid after desflurane anesthesia with awakening within 5-10 minutes. Patients may therefore need postoperative pain relief early.

Side effects

Desflurane may trigger cough and airway obstruction as well as increased airway mucous production. It should not be used for induction of anesthesia. It has dose dependent cardiac depression.

Warning

To rapid increase desflurane in the inspiratory air can cause respiratory irritation with bronchospasm and increased mucus secretion. Cough, laryngospasm, apnea and bronchospasm may occur. Desflurane is not recommended for induction by spontaneous breathing in children. May trigger malignant hyperthermia in predisposed patients. Caution in patients with elevated intracranial pressure.


Suxamethonium (Succinylcholine)

Depolarizing muscle relaxant. Ultra-short acting means with very fast elimination. For intravenous use only. Adjuvant to general anesthesia to facilitate endotracheal intubation and to provide relaxation of skeletal muscle during surgical interventions of short duration. To facilitate manual ventilation of an injured patient.

Intubation dose: 1-1.5 mg/kg intravenously = 25-100 mg i v (pretreatment with atropine), 50 mg/ml solution.

Standard dose: 75 mg i v, 50-100 mg, 1-2 ml i v.

Caution: Hyperkalaemia, recent burn, malignant hyperthermia, muscular disease, major tissue damage, bradycardia.

Brand name: Celocurin®


Rocuronium

Non-depolarizing muscle relaxant drug. Adjuvant to general anesthesia to facilitate endotracheal intubation and to provide relaxation of skeletal muscles during medium to long duration surgical procedures. Usually, patients are paralyzed under abdominal surgery (open or laparoscopic), orthopedic surgery and in other surgery where the patient must lay absolutely still. To facilitate manual or mechanical ventilation of the injured patient.

Intubation dose: 0.6 mg/kg iv (1.0 mg/kg at RSI); 40-60 mg to normal adult adult = 4-6 ml, 10 mg/ml solution (formerly Tracrium).

Standard dose: 50 mg i.v. Maintenance 0.15 mg/kg 10-20 mg per occasion. Giving every 20 minutes to 60 minutes during anesthesia. Spontaneous recovery after about 35 minutes.

Caution: Allergic reactions. Previous reaction to muscle relaxants, myasthenia or similar neuromuscular disease. Can not be given i.m.

Reversal: Cholinesterase inhibitors Robinul-Neostigmine 1-2 ml intravenously (neostigmine 2.5-5 mg + glycopyrron 0.5-1 mg).

Brand name: Esmeron®


Vecuronium

Non-depolarizing muscle relaxant drug. Adjuvant to general anesthesia to facilitate endotracheal intubation and to provide relaxation of skeletal muscles during medium to long duration surgical procedures. Usually, patients are paralyzed during abdominal surgery (open or laparoscopic), orthopedic surgery and in other surgery where the patient must lay absolutely still. To facilitate manual or mechanical ventilation of the injured patient.

Intubation dose: 0.08-0.1 mg/kg i v, 8-12 mg to normal adult. 2 mg/ml solution = 4-6 ml.

Standard dose: 10 mg i v. Maintenance 0.02 to 0.03 mg/kg, 1-3 mg per occasion. Giving every 20 minutes to 60 minutes during anesthesia.

Caution: Previous reaction to muscle relaxants, myasthenia gravis or similar neuromuscular disease.

Reversal: Robinul-Neostigmin 1-2 ml intravenously (neostigmine 2.5-5 mg + glycopyrron 0.5-1 mg) alt. Atropine 1 mg + Neostigmine 2.5 mg i v.

Brand name: Norcuron® – deregistered


Atracurium

Non-depolarizing muscle relaxant drug. Adjuvant to general anesthesia to facilitate endotracheal intubation and to provide relaxation of skeletal muscles during medium to long duration surgical procedures. Usually, patients are paralyzed under the abdominal surgery (open or laparoscopic), orthopedic surgery and in other surgery where the patient must be absolutely still. To facilitate manual or mechanical ventilation of the injured patient.

Intubation dose: 0.6 mg/kg i v (1.0 mg/kg at RSI); 40-60 mg to normal adult = 4-6 ml, 10 mg/ml solution .

Standard dose: 50 mg i.v. Maintenance dose is 0.15 mg/kg, 10-20 mg per occasion. Repeated dose every 20 to 60 minutes during anesthesia. Spontaneous recovery after about 35 minutes.

Caution: Allergic reactions. Previous reaction to muscle relaxants, myasthenia or similar neuromuscular disease. Cannot be given i.m.

Reversal: Cholinesterase inhibitor Robinul-Neostigmine 1-2 ml intravenously (neostigmine 2.5-5 mg + glycopyrronium 0.5-1 mg).

Brand name: Atrakurium-hameln®  (formerly Tracrium®)


Neostigmine

Neostigmine is a cholinesterase inhibitor that increases the acetylcholine concentration as needed, interrupts the effect of muscle relaxants and muscle activity and muscle strength return after muscle relaxation under anesthesia. Used to reverse the effects of non-depolarizing muscle relaxant anesthetic agents at the end of anesthesia. Neostigmine may also be needed to create intestinal peristalsis in intestinal paralysis and to increase muscle activity in myasthenia gravis. Administration of neostigmine is preceded by intravenous administration of an anticholinergic (atropine sulphate or glycopyrrone). Neostigmine is then given at a dose of 0.5-2.5 mg (0.2-1 ml) intravenously. In exceptional cases, doses up to 5 mg (2 ml) may be needed. The injection should be given slowly and with regard to effect.

Concentration: 2.5 mg/ml iv

Dosage

30-70 ug/kg. Standard dose for reversal 2.5 mg = 1 ml. In case of insufficient effect, half the standard dose can be repeated (after 10-15 minutes) = 0.5 ml.

Combined routinely with anticholinergics in the form of atropine or glycopyrrone to avoid bradycardia and bronchospasm.

  • Neostigmine 2.5 mg + 0.5 mg glycopyrrone (Robinul) (1 ml)
  • Neostigmine 2.5 mg (1 ml) + 0.5 mg atropine (1 ml)

Caution

During concomitant treatment with beta-blockers, bradycardia and hypotension may occur.