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- Patients with severe coronavirus disease 2019 (Covid-19) may become critically ill with acute respiratory distress syndrome that typically begins approximately 1 week after the onset of symptoms.
- Deciding when a patient with severe Covid-19 should receive endotracheal intubation is an essential component of care.
- After intubation, patients should receive lung-protective ventilation with plateau pressure less than or equal to 30 cm of water and with tidal volumes based on the patient’s height.
- Prone positioning is a potential treatment strategy for refractory hypoxemia.
- Thrombosis and renal failure are well-recognized complications of severe Covid-19.
- Dexamethasone has been shown to reduce mortality among hospitalized patients with Covid-19 who require oxygen, particularly those receiving mechanical ventilation.
- Remdesivir was recently approved by the Food and Drug Administration for the treatment of Covid-19 in hospitalized patients, on the basis of randomized trials showing that the drug reduces time to clinical recovery; however, more data are needed to inform its role in treating severe Covid-19.
These recommendations are intended to support the treatment of COVID-19 patients and will be continuously revised. Author:
Francesca Campoccia Jalde, Chief Physician
TICU Solna, Perioperative Medicine and Intensive Care
Karolinska University Hospital, Stockholm
Johan Petersson, Chief Physician
ICU Solna, Perioperative Medicine and Intensive Care
Karolinska University Hospital, Stockholm
Patients cared for outside ICU
- O2 supply with target SpO2 92-96%; in patients with COPD or risk of CO2 retention target SpO2 88-92% 1.
- When O2 supply, including supply with reservoir mask, is not sufficient, high flow via nasal mask (HFNC, “Optiflow”) is recommended.
- When HFNC is not sufficient, CPAP with pressure ≤ 10 cm H2O can be tested.
- The experience is that COVID-19 patients who are completely dependent on NIV, ie. can not maintain sufficient gas exchange without NIV, often continues to deteriorate. This can lead to a need for uracute intubation, which means increased risks for the patient and an increased risk of spreading the infection. For patients with less pronounced lung weight, NIV can be an alternative that is used for a longer period of time, possibly. alternating with HFNC. In the same way, NIV can be used for patients where intensive care is not relevant but is avoided if you have switched to palliative care.
- HFNC, CPAP and NIV entail a risk of aerosol formation and the spread of infection, which strengthens the indication for protective equipment. Compared to CPAP / NIV, HFNC can bring an advantage through less need to be very close to the patient.
- HFNC and NIV should not be used for transport within the hospital, reservoir worm is used instead.
- Mobilization, cough relief and changes in position are important to prevent and treat impaired lung function. It has proven particularly effective with a prone side position or abdominal position, with or without other respiratory support such as HFNC, NIV or CPAP.
Potential indications for intensive care
- PaO2/FIO2 < 20 kPa or deterioration with need for increasing FIO2 (O2%), SpO2 <93% with O2 ≥ 10 L/min on mask.
- Rising PCO2 (> 6.0 kPa), especially if pH < 7.30.
- Increased respiratory work and / or respiratory rate (AF)> 30 / min. Ask the patient if it has gotten better or worse with breathing over time.
- When NIV is used for patients due to that oxygen on the reservoir worm or HFNC is insufficient treatment and the patient continues to deteriorate or that the patient has not improved within 1-2 hours after starting treatment.
- Affected level of consciousness.
- Hypotension, oliguria, elevated and rising β-Lactate, echocardiography with pronounced right and/or left failure.
- Before ICU contact is made, in the normal case, ev. treatment limitations have been discussed in the care unit even before these indications exist, see above. If the patient meets any ICU indication, ICU contact should be made in parallel with this discussion. The responsibility for this lies primarily with the responsible doctor in the department where the patient is cared for.
The intubation procedure is linked to an increased risk of infection of the staff, especially for the intubator and a risk of circulatory / respiratory collapse. COVID-19 patients may appear relatively unaffected despite significant hypoxia and high respiratory rate. They can deteriorate very quickly and then have a very hard time recovering after intubation. It is therefore a strong recommendation not to wait too long with intubation. Intubation of COVID-19 patients always involves an increased risk of infection. For procedure and checklist, see special guideline, https://sfai.se/download-attachment/11747.
Recommendations regarding ventilator treatment
Humidification/filter – Secretion stagnation and “tube stop” are relatively common, active humidification with conventional equipment is a pre-selection. If active humidification is not used, passive humidification with HME with filter function is provided. Always use filters at the ventilator inlet expiration. All changes of filters / hoses are made with the ventilator in standby. Auto-PEEP and patient-ventilator dyssynchrony may be due to filters that need to be replaced – especially if the patient has active humidification and/or inhalations. Testing of new tubes can be skipped in consultation with the responsible doctor.
Closed suction system – always used.
Tidal volume/Drive pressure – generally tidal volume up to 8 ml/kg PBW is accepted if drive pressure ≤ 15 cm H2O and plateau pressure ≤ 30 cm H2O. Larger tidal volume / driving pressure is accepted when reduction is impossible or requires measures that are deemed to worsen the situation such as increased sedation, need for relaxation or reduced gas exchange.
PEEP – selected individually, if good compliance often 6-12 cm H2O even at higher FIO2. Try higher PEEP for lower compliance and low PaO2 / FIO2. Re-evaluate high PEEP by reduction with 2 cmH2O and follow-up of tidal volume, compliance and gas exchange. Note that compliance can only be assessed with controlled ventilation.
SpO2/PaO2– target values:
- 88-94%, 7.5-9.5 kPa on controlled ventilation
- 92-94% 8.5-9.5 kPa on assisted ventilation
- PaCO2 – up to 8.0 kPa is generally accepted. Higher PaCO2 can be accepted if pH> 7.20 with simultaneous reasonable breathing drive. Higher PaCO2 can also be accepted if the ventilation otherwise leads to excessive tidal volumes/drive pressure or significant auto-PEEP.
Pulmonary recruitment – early consideration of low PaO2/FIO2 and low compliance, especially of sudden deterioration. Exclude bronchial intubation, secretion / threatening tube obstruction, pneumothorax. Do not repeat recruitment if previous recruitment has not had an effect.
Patient-ventilator dyssynchrony – managed primarily with adjustment of ventilator settings and increased sedation, secondarily with intermittent muscle relaxants or infusion to be reconsidered after 12-24 hours.
Abdominal position treatment – recommended if PaO2 / FIO2 <20 kPa and even in case of PCO2 problems, strive for at least 16 h/day, daily turn with 4-6 h in supine position.
Weaning Due to slow improvement and risk of “setbacks” regular training begins relatively late in the process and only at lower ventilator settings than is otherwise usual.
Humidification/use of filters in the ventilator circuit (“hoses”) in case of suspected or secured COVID-19
Fluid balance between the risk of spreading the infection and what is optimal for the patient.
Make a patient- and situation-based choice between active and passive humidification. Active humidification is preferable. Indication for active humidification is particularly present in case of pronounced hypercapnea with the need to eliminate dead space or in case of tough / dry secretions. Dry / tough secretions can cause tube obstruction or auto-PEEP. If active humidification is not possible, one can consider e.g. acetylcysteine inhalations but then via a “closed” nebulization system.
Passive humidification is done primarily with HME (moisture-heat exchanger) which also has a filter function. This should be placed as close to the tube as possible, but the closed suction system must be between the tube and the HME / filter.
If HME with filter function is missing, another HME is used which is supplemented with filters at the fan’s inspiration output.
There should always be a filter on the exhalation input on the fan.
If active humidification is used, the HME / filter at the tube should not be used, however, there should be a filter at the ventilator’s inspiration outlet.
For all filter changes, hose changes and the like, the tube must be clamped briefly and the fan put in Stand-By before disconnections are made. The fan will not start until you have ensured that everything is connected again. For tracheotomized patients, this is done in the same way but without clamping.
- With pressure control, drive pressure is selected for the desired tidal volume, then AF is adjusted to the desired minute ventilation and an acceptable PaCO2, but avoid auto-PEEP.
- Accept tidal volume approx. 8 ml/kg PBW (predicted body weight) if the driving pressure ≤ 15 cm H2O (driving pressure = pressure over PEEP, the ventilating pressure). Aim gradually towards lower tidal volume / kg PBW if the drive pressure is higher.
- Note that the driving pressure can really only be assessed with controlled ventilation. For pressure-assisted ventilation, the proposal is to accept tidal volumes up to 8 ml/kg PBW, provided that the support is a maximum of 14 cm H2O and the patient does not “pull” much inhalation himself. If this cannot be achieved, controlled ventilation or measures to reduce respiratory drive are proposed, e.g. increased sedation.
- Note that reducing pressure support to reduce tidal volume often has little effect but leads to increased respiratory work. It is therefore rarely appropriate with pressure supports < 8-10 cm H2O. At high tidal volumes, it may be appropriate to increase the pressure support if the patient has a large respiratory work. The result is often unchanged tidal volume but with reduced breathing work. The alternative is to switch to controlled ventilation.
- Larger tidal volume/driving pressure is accepted when reduction is impossible or where the alternative is measures that are judged to worsen the situation, such as deeper sedation, need for muscle relaxation, impaired gas exchange, pronounced patient-ventilator dysynchrony.
- The goal is top pressure ≤ 30 cm H2O and driving pressure ≤ 15 cm H2O. Always strive for the lowest possible driving pressure.
- FiO2 with target SpO2 88-94%, and 92-94% for pressure assisted ventilation.
- PEEP is selected individually, often 6-12 cm H2O. Lower PEEP is often chosen than with other ARDS, especially if the patient has high compliance (> compliance 30 ml / cm H2O).
- When high FIO2 is needed, ie. moderate-severe ARDS, higher PEEP can be tried, especially at low compliance. If higher PEEP does not lead to improved gas exchange or improved compliance, or if increased PEEP leads to hemodynamic deterioration, return to lower PEEP. In the same way, PEEP> 8-10 cm H2O should be reconsidered at least daily, but first inquire about the effect of previous attempts at reduction. Changes are made in steps of 2 cm H2O.
- Hypercapne due to Difficult CO2 elimination is accentuated by high PEEP, especially in relative hypovolemia. Consider giving volume and reducing PEEP, a lower
- PEEP may be better overall even if it means that FIO2 must be increased.
- Consider early pulmonary recruitment with increased PEEP and increased airway pressure if the patient has low PaO2 / FIO2 and low compliance (<c. 20 ml / cm H2O) but recruit with increased caution in case of hypovolemia / hemodynamic instability. Do not repeat recruitment attempts if they have not previously had an effect.
- Patient-Ventilator Dysynchrony. When the patient is difficult to ventilate and does not follow the ventilator (“breathing against”), it is handled with increased sedation (incl. Increased opiate dose). If this is not enough, repeated doses of muscle relaxation or infusion for up to 24-48 hours may be tried. In the event of a very severe gas exchange disturbance, caution is recommended when switching from assisted to controlled ventilation. There is a risk that this shift may cause respiratory collapse. The solution can then be a quick return to spontaneous breathing with assisted ventilation e.g. with reversal of drugs.
Avoid aerosol formation by not disconnecting the fan hoses / tube as far as possible. This recommendation also aims to avoid derecryption (atelectasis formation).
- Use closed suction system.
- Avoid inhalation therapy except in case of strong indication.
- Minimize the number of bronchoscopies. Bronchoscopy is performed for diagnosis and in case of imminent risk of tube obstruction. Use muscle relaxants during bronchoscopy, but with readiness for reversal (see comment in the section on patient-ventilator dyssynchrony above). Blind protected brush is an alternative for diagnostics.
- If disconnection is unavoidable, put the ventilator in Stand-By and clamp the tube with peang. Consider sedation bolus before doing this. Switch to active ventilation only when all hoses are connected.
Abdominal position treatment at least 16 h/day is recommended if PaO2/FIO2 <20 kPa in supine position. Abdominal position in COVID-19 ARDS often has a favorable effect and can therefore be tested at higher PaO2/FIO2, e.g. in case of gradual deterioration of oxygenation or when the problem is more hypercapne than hypoxemia. If “true abdominal position” is difficult to achieve, prone side position is an option. In both cases, small adjustments should be made so that pressure points and the position of the head / neck change regularly.
Other ventilation methods: There are no studies that have shown clear advantages of using other ventilation methods than pressure control and pressure support. In the current situation with very varying experience and competence of both doctors and nursing staff, it is recommended that one refrains from using ventilation methods that are not used in ordinary cases. Ie. use only pressure control and pressure support. Pressure-controlled ventilation with controlled tidal volumes e.g. VKTS is used in special cases where stable PaCO2 levels are required.
If the patient has well-functioning controlled ventilation, you should not be in a hurry to switch to pressure support. Wait for PaO2 / FIO2 ≥ 33 kPa (approximately equivalent to SpO2 95% at FIO2 0.3) and that the patient does not breathe with excessive tidal volumes (eg> 10 ml / kg PBW) with assisted ventilation. For the same reason, PEEP should not be reduced to <6 cm H2O until a relatively late stage in the process. Pronounced impaired oxygenation at turns indicates that the patient is not ready for extubation. Experience so far is that patients with COVID-19 ARDS require at least 10-14 days of intensive care. During intensive care, the patient should be considered infectious. Extubation should be done at a later stage of the process, ie. in a situation where the need for continued respiratory support after extubation is judged to be low.
Extubation: Several centers have reported airway obstruction after extubation, it is unclear if and why this may be more common in COVID-19 than other pneumonia / ARDS. Secretion stagnation problems are common after extubation, they are treated in the usual way with cough relief and mobilization. In selected cases, tracheotomy may probably allow less risk of reintubation and a faster termination of intensive care, but this presupposes that the patient can be discharged to care units with the right skills and staffing.
Refractory hypoxemia/hypercapnea: Possible measures are recruitment, abdominal position, optimizing PEEP (may mean lowering of PEEP), minimizing device dead space, hemodynamic assessment / optimization (excluding hypovolemia as a cause of impaired CO2 elimination), deepened sedation, neuromuscular blockade fever, acceptance of spontaneous breathing / assisted ventilation despite greater tidal volumes / airway pressure than desired, inhalation of vasodilators (there are positive experiences from inhalation of iloprost and milrinone), consultation with ECMO. A high frequency of pulmonary embolism in COVID-19 patients has been described, which strengthens the indication for diagnosis in this regard.
ECMO: Consider contact with ECMO if the patient does not improve with the previously mentioned measures and severe hypoxemia persists (eg PaO2 / FiO2 <10 KPa) and no contraindications are present. The indication for ECMO may change during the epidemic.
Tracheotomy: Use protective equipment, use muscle relaxants to avoid coughing, feel free to cover the face / tube with plastic wrap, put the ventilator in stand-by when the tube is backed up and the trachea should be incised. Make sure that all hoses are connected and that the needle is cupped before restarting the fan. See link for description of ARDS at COVID 19 and references
Respiratory treatment graphics
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