COVID-19 – Corona Virus English

Respiratory Failure and Ventilator Treatment in Severe Covid-19 Infection

Disease Course in Covid-19 Infection

• Patients with severe coronavirus disease 2019 (Covid-19) can become critically ill with acute respiratory distress that typically begins approximately one week after the onset of symptoms.
• Determining when a patient with severe Covid-19 should undergo endotracheal intubation is a crucial part of care.
• After intubation, patients should receive lung-protective ventilation with a plateau pressure less than or equal to 30 cm H2O and tidal volumes based on the patient’s height.
• Prone positioning is a potential treatment strategy for severe hypoxemia.
• Thrombosis and kidney failure are well-known complications of severe Covid-19.
• Dexamethasone has been shown to reduce mortality among hospitalized Covid-19 patients who need oxygen, especially those receiving mechanical ventilation.
• Remdesivir was recently approved by the Food and Drug Administration for the treatment of Covid-19 in hospitalized patients based on randomized studies showing that the drug reduces the time to clinical recovery; however, more data is needed to inform its role in treating severe Covid-19.

Patients Cared for Outside ICU

• O₂ supply with a target SpO₂ of 92-96%; in patients with COPD or risk of CO₂ retention, target SpO₂ 88-92%.
• When O₂ supply, including supply with a reservoir mask, is insufficient, high-flow nasal cannula (HFNC, “Optiflow”) is recommended.
• When HFNC is insufficient, CPAP with a pressure ≤ 10 cm H₂O can be attempted.
• Experience has shown that COVID-19 patients who are entirely dependent on NIV (non-invasive ventilation) and cannot maintain adequate gas exchange without it, often continue to deteriorate, potentially leading to urgent intubation, increasing patient risks and the spread of infection. In patients with less severe lung failure, NIV may be an alternative used for a longer period, possibly alternating with HFNC. Similarly, NIV can be used for patients not suitable for intensive care, but it should be avoided if shifted to palliative care.
• HFNC, CPAP, and NIV carry a risk of aerosol formation and infection spread, strengthening the need for protective equipment. Compared to CPAP/NIV, HFNC may offer an advantage as it requires less proximity to the patient.
• HFNC and NIV should not be used during hospital transport, use a reservoir mask instead.
• Mobilization, cough assistance, and position changes are essential for preventing and treating lung function deterioration. Prone positioning has proven particularly effective, with or without additional respiratory support such as HFNC, NIV, or CPAP.

Potential Indications for Intensive Care

• PaO₂/FIO₂ < 20 kPa or deterioration with increasing FIO₂ requirements (O₂ %), SpO₂ < 93% with O₂ ≥ 10 L/min on a mask.
• Rising PCO₂ (> 6.0 kPa), especially if pH < 7.30.
• Increased respiratory effort and/or respiratory rate (RR) > 30/min. Ask the patient if breathing has improved or worsened over time.
• When NIV is used because oxygen therapy with a reservoir mask or HFNC is insufficient, and the patient continues to deteriorate or has not improved within 1-2 hours of treatment initiation.
• Altered level of consciousness.
• Hypotension, oliguria, elevated and rising P-Lactate, cardiac echo with significant right and/or left heart failure.
• Before contacting ICU, any treatment limitations should, in most cases, have already been discussed at the care unit before these indications arise. If the patient meets any ICU indication, ICU contact should be made in parallel with this discussion. The responsibility primarily lies with the attending physician at the unit where the patient is being cared for.

Intubation

The intubation procedure is associated with an increased risk of infection for staff, especially for the person intubating, and there is a risk of circulatory/respiratory collapse. COVID-19 patients may appear relatively unaffected despite significant hypoxia and high respiratory rates. They can deteriorate rapidly and have a hard time recovering after intubation. Therefore, it is strongly recommended not to wait too long for intubation. Intubation of COVID-19 patients always carries an increased risk of infection spread.

Ventilator treatment (Graphic Illustration)

Recommendations Regarding Ventilator Treatment

Humidification/Filter

Secret stasis and “tube blockage” are relatively common; active humidification with conventional equipment is the first choice. If active humidification is not used, passive humidification with HME (heat and moisture exchanger) with filter function is provided. Always use a filter at the ventilator’s expiration port. All filter/tube changes are made with the ventilator in standby. Auto-PEEP and patient-ventilator dyssynchrony can be due to filters needing replacement, particularly if the patient has active humidification and/or inhalations. Testing of new tubes can be skipped in consultation with the responsible physician.

Closed Suction System

Always used.

Tidal Volume/Driving Pressure

In general, tidal volumes up to 8 ml/kg PBW (predicted body weight) are acceptable if driving pressure is ≤ 15 cm H₂O and plateau pressure is ≤ 30 cm H₂O. Higher tidal volumes/driving pressures are accepted when reduction is impossible or would require interventions deemed to worsen the situation, such as increased sedation, relaxation, or impaired gas exchange.

PEEP

PEEP is chosen individually, typically 6-12 cm H₂O with good compliance, even at higher FIO₂. Try higher PEEP if compliance is low and PaO₂/FIO₂ is low. Reassess high PEEP by reducing it by 2 cm H₂O and monitoring tidal volume, compliance, and gas exchange. Note that compliance can only be assessed during controlled ventilation.

SpO₂/PaO₂ Target Values

• 88-94%, 7.5-9.5 kPa during controlled ventilation
• 92-94%, 8.5-9.5 kPa during supported ventilation

PaCO₂

Generally, PaCO₂ up to 8.0 kPa is accepted. Higher PaCO₂ may be accepted if pH > 7.20, with reasonable respiratory drive. Higher PaCO₂ may also be accepted if ventilation otherwise requires excessively high tidal volumes/driving pressures or significant auto-PEEP.

Lung Recruitment

Considered early if low PaO₂/FIO₂ and low compliance, especially if there is sudden deterioration. Exclude bronchial intubation, secretions/threatening tube blockage, pneumothorax. Do not repeat recruitment if previous attempts had no effect.

Patient-Ventilator Dyssynchrony

Primarily managed by adjusting ventilator settings and increasing sedation; secondly with intermittent or continuous muscle relaxants, reassessed after 12-24 hours.

Prone Positioning

Recommended if PaO₂/FIO₂ is < 20 kPa and even in PCO₂ issues, aiming for at least 16 hours/day, with daily rotations of 4-6 hours in the supine position.

Weaning

Due to slow improvement and the risk of setbacks, proper weaning is initiated relatively late in the process, and at lower ventilator settings than usual.

Humidification/Use of Filters in the Ventilator Circuit (”Tubes”) for Suspected or Confirmed COVID-19

Balance between the risk of infection spread and what is optimal for the patient.

• Make a patient- and situation-based choice between active and passive humidification. Active humidification is preferable. Indications for active humidification exist, particularly with pronounced hypercapnia requiring dead space elimination or thick/dry secretions. Thick/dry secretions can cause tube blockage or auto-PEEP. If active humidification is not possible, consider acetylcysteine inhalations, but only via a “closed” nebulization system.
• Passive humidification is primarily done with HME (heat-moisture-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 an HME with a filter function is unavailable, use another HME supplemented with a filter at the ventilator’s expiration port.
• There should always be a filter at the ventilator’s expiration port.
• If active humidification is used, the HME/filter at the tube should not be used, but a filter should be placed at the ventilator’s expiration port.
• During all filter changes, tube changes, etc., the tube should be briefly clamped, and the ventilator set to standby before disconnection. The ventilator should not be started until everything is reconnected. For tracheotomized patients, this is done similarly but without clamping.

Invasive Ventilation

• With pressure control, driving pressure is chosen for the desired tidal volume, then the respiratory rate (RR) is adjusted to achieve the desired minute ventilation and acceptable PaCO₂ levels, avoiding auto-PEEP.
• Accept tidal volume up to approximately 8 ml/kg PBW (predicted body weight) if the driving pressure is ≤15 cm H₂O (driving pressure = pressure above PEEP, the ventilating pressure). Gradually aim for a lower tidal volume/kg PBW if driving pressure is higher.
• Note that driving pressure can only truly be assessed during controlled ventilation. In pressure-supported ventilation, it is suggested to accept tidal volumes up to 8 ml/kg PBW, provided the support pressure is a maximum of 14 cm H₂O and the patient is not contributing significantly to inspiratory effort. If this cannot be achieved, consider controlled ventilation or interventions to reduce respiratory drive, such as increased sedation.
• Reducing pressure support to lower tidal volume often has little effect but leads to increased respiratory effort. Therefore, pressure support < 8-10 cm H₂O is rarely appropriate. In cases of high tidal volumes, it may be correct to increase pressure support if the patient has high respiratory effort. The result is often unchanged tidal volume but reduced respiratory effort. The alternative is to switch to controlled ventilation.
• Higher tidal volumes/driving pressures are accepted when reduction is impossible or when alternatives such as deeper sedation, muscle relaxation, impaired gas exchange, or significant patient-ventilator dyssynchrony are considered to worsen the situation.
• The goal is to keep **peak pressure ≤ 30 cm H₂O** and **driving pressure ≤ 15 cm H₂O**. Always strive for the lowest possible driving pressure.
• FiO₂ should be set with a target SpO₂ of 88-94%, and 92-94% in pressure-supported ventilation.
• PEEP is selected individually, often 6-12 cm H₂O. Lower PEEP is typically chosen compared to other ARDS cases, especially if the patient has high compliance (compliance > 30 ml/cm H₂O).
• In cases of high FiO₂ needs, i.e., moderate to severe ARDS, higher PEEP can be attempted, especially with low compliance. If higher PEEP does not improve gas exchange or compliance, or if it leads to hemodynamic deterioration, return to lower PEEP. Similarly, PEEP >8-10 cm H₂O should be reassessed daily, but first assess the effect of previous attempts to reduce it. Changes should be made in steps of 2 cm H₂O.
• Hypercapnia due to impaired CO₂ elimination is exacerbated by high PEEP, particularly in cases of relative hypovolemia. Consider providing volume and reducing PEEP, as a lower PEEP may overall be better even if it requires increasing FiO₂.
• Consider early lung recruitment with increased PEEP and airway pressures if the patient has low PaO₂/FiO₂ and low compliance (< 20 ml/cm H₂O). Exercise caution during recruitment if the patient is hypovolemic or hemodynamically unstable. Do not repeat recruitment attempts if they have previously been ineffective.
• **Patient-Ventilator Dyssynchrony:** If the patient is difficult to ventilate and does not follow the ventilator (“breathing against it”), it is managed with increased sedation (including increased opioid doses). If this is insufficient, consider repeated doses of muscle relaxation or continuous infusion for up to 24-48 hours. In cases of severe gas exchange disturbances, caution is advised when switching from supported to controlled ventilation, as this transition may cause respiratory collapse. The solution may be to return quickly to spontaneous breathing with supported ventilation, e.g., by reversing medications.

Avoid aerosol generation by keeping ventilator tubes/tube disconnections to a minimum. This recommendation also aims to avoid derecruitment (atelectasis).

• Use a closed suction system.
• Avoid inhalation therapy except for strong indications.
• Minimize the number of bronchoscopies. Bronchoscopy is performed for diagnostic purposes and in cases of imminent tube blockage. Use muscle relaxants during bronchoscopy, but be prepared for reversal (see comments on patient-ventilator dyssynchrony above). A blind protected brush is an alternative for diagnosis.
• If disconnection is unavoidable, the ventilator should be set to Stand-By, and the tube clamped with forceps. Consider sedation bolus before this is done. Resume active ventilation only when all tubes are reconnected.

Prone positioning for at least 16 hours per day is recommended if PaO₂/FiO₂ < 20 kPa in the supine position. Prone positioning in COVID-19 ARDS often has a beneficial effect and can be attempted at higher PaO₂/FiO₂, e.g., in cases of gradual oxygenation deterioration or when the issue is more related to hypercapnia than hypoxemia. If “true prone positioning” is difficult to achieve, prone-side positioning is an alternative. In both cases, small adjustments should be made regularly to change pressure points and the position of the head/neck.

Other Ventilation Methods

There are no studies that have shown clear advantages in using other ventilation methods beyond pressure control and pressure support. In the current situation, where experience and expertise among both doctors and nursing staff vary widely, it is recommended to avoid using ventilation methods that are not typically employed. Therefore, use only pressure control and pressure support. Pressure-controlled ventilation with controlled tidal volumes, such as VC-TS, is used in specific cases where stable PaCO₂ levels are required.

Sedation/Weaning

If the patient is well-managed with controlled ventilation, do not rush to switch to pressure support. Wait until PaO₂/FiO₂ ≥ 33 kPa (approximately equivalent to SpO₂ 95% with FiO₂ 0.3) and the patient is not breathing with excessively large tidal volumes (e.g., > 10 ml/kg PBW) during supported ventilation. For the same reason, PEEP should not be reduced to < 6 cm H₂O until a relatively late stage in the process. Marked oxygenation deterioration during turning indicates that the patient is not ready for extubation. Experience so far suggests that patients with COVID-19 ARDS require at least 10-14 days of intensive care. During ongoing intensive care, the patient should be considered infectious. Extubation should occur later in the course when the need for continued respiratory support after extubation is assessed as low.

Extubation

Several centers have reported airway obstruction after extubation; it is unclear whether this is more common with COVID-19 than with other pneumonia/ARDS cases. Problems with secretion stagnation are common after extubation and are managed as usual with cough assistance and mobilization. In selected cases, tracheotomy may reduce the risk of reintubation and allow for a quicker end to intensive care, but this requires that the patient can be transferred to care units with the right expertise and staffing.

Refractory Hypoxemia/Hypercapnia

Possible interventions include recruitment, prone positioning, optimizing PEEP (this may mean reducing PEEP), minimizing apparatus dead space, hemodynamic evaluation/optimization (rule out hypovolemia as a cause of impaired CO₂ elimination), deep sedation, neuromuscular blockade, treating fever, acceptance of spontaneous breathing/supported ventilation despite larger tidal volumes/airway pressures than desired, inhalation of vasodilating medications (positive experiences with inhalation of iloprost and milrinone have been reported), and consultation with ECMO specialists. A high incidence of pulmonary embolism has been described in COVID-19 patients, strengthening the indication for diagnostics in this regard.

ECMO

Consider contacting ECMO if the patient does not improve with the previously mentioned measures and severe hypoxemia persists (e.g., PaO₂/FiO₂ <10 KPa) and there are no contraindications. The indication for ECMO may change during the pandemic.

Tracheotomy

Use protective equipment, and use muscle relaxants to avoid coughing. Preferably cover the face/tube with a plastic sheet, and set the ventilator to standby when the tube is backed out, and the trachea is incised. Ensure all tubes are connected and the cannula is cuffed before restarting the ventilator. For a description of ARDS in COVID-19 and references, see the following link: https://sfai.se/download-attachment/11747.

Respiratory Treatment in Respiratory Failure in Covid 19

Definition of ARDS

• Acute lung failure (≤ 7 days)
• The lung failure is not entirely explained by heart failure
• Bilateral infiltrates (X-ray/CT/ultrasound)
• PaO₂/FiO₂ < 40 kPa despite PEEP 5 cm H₂O

Overall Recommendations

• Avoid a positive fluid balance if possible, especially as ARDS severity increases.
• With increasing ARDS severity, there is a greater need for hemodynamic evaluation (cardiac echo) and specific interventions in the event of right-sided heart failure.
• Ensure appropriate diagnosis and treatment of the underlying etiology, including infection diagnostics and treatment.
• The level of sedation should be chosen for patient comfort, avoid excessive respiratory effort (if using pressure support) and prevent patient-ventilator dyssynchrony.
• Prophylaxis for DVT, stress ulcers, VAP, and pressure sores.

In ARDS, there is often but not always, a correlation between the degree of oxygenation problems (lower PaO₂/FiO₂) and lower compliance. This is due to large lung areas that are not filled with gas or ventilated. When a smaller portion of the lungs is ventilated, compliance becomes low, and blood flow through unventilated parts becomes an intrapulmonary shunt, explaining hypoxemia that responds poorly to increased FiO₂. With this pathophysiology, improved oxygenation and compliance are often, but not always, seen with increased PEEP and after lung recruitment using high airway pressures. The mechanism is that lung areas that were previously not filled with gas or ventilated open up, which means that more of the lungs are ventilated, leading to better compliance and less shunt. This is the logic when the need for increased FiO₂ is connected to the use of higher PEEP (PEEP-FiO₂ tables).

Over the past few months, there has been an intense debate about whether COVID-19-induced ARDS systematically differs from ARDS caused by other conditions, such as pneumonia. In several, relatively large, patient studies, it has been difficult to demonstrate clinically significant differences, for example, in compliance.

At the same time, we have also locally experienced that the combination of severe ARDS (low PaO₂/FiO₂ ratio) and relatively high (almost normal) compliance is relatively common. However, this is also observed in ARDS of other etiologies than COVID-19. For all patients with ARDS, regardless of etiology, the choice of treatment, such as ventilator settings, must be continuously adapted to the current situation. An example of this is when severe oxygenation problems (low PaO₂/FiO₂) are associated with well-preserved, almost normal, compliance. Well-preserved compliance indicates that the low PaO₂/FiO₂ is not explained by lung areas without ventilation, which means that there is less potential for higher PEEP to improve gas exchange or compliance. Well-preserved compliance and the absence of large lung areas that are not filled with gas or ventilated are consistent with the radiological findings commonly seen in COVID-19 pneumonia: ground-glass type infiltrates and the absence of larger consolidated lung areas.

The oxygenation issue in this situation has instead been suggested to result from V/Q mismatch combined with impaired hypoxic vasoconstriction. In this situation, slightly lower PEEP and slightly higher tidal volumes become reasonable. High PEEP can worsen gas exchange, especially CO₂ elimination, through several mechanisms. This is not specific to COVID-19 patients, but it becomes particularly important as PEEP seems less likely to open unventilated lung areas. The deterioration in gas exchange with increased PEEP becomes more pronounced if the patient is relatively hypovolemic. With preserved lung compliance, PEEP has a greater effect on preload than in ARDS with decreased compliance. Deteriorated cardiac output caused by high PEEP and relative hypovolemia has been suggested to contribute to acute kidney failure in COVID-19 patients. Other patients with COVID-19 pneumonia describe a pathophysiology more typical of “regular” ARDS: reduced compliance and shunt due to lung areas that are not filled with gas or ventilated, combined with improved gas exchange with increased PEEP/lung recruitment. In this situation, the indication to limit tidal volume and test higher PEEP is strengthened.

The discussion about different types of ARDS will likely continue. Regardless, the overall experience seems to support greater restraint with higher PEEP and acceptance of higher tidal volumes than in COVID-19 ARDS, but there may also be patients or situations where the pathophysiology more closely resembles “regular” ARDS.

ARDS in Covid-19 Infection

In ARDS, there is often, but not always, a correlation between the degree of oxygenation problems (lower PaO₂/FiO₂) and lower compliance. This is due to large lung areas that are not filled with gas or ventilated. When a smaller portion of the lungs is ventilated, compliance becomes low, and blood flow through unventilated parts becomes an intrapulmonary shunt, explaining hypoxemia that responds poorly to increased FiO₂. With this pathophysiology, improved oxygenation and compliance are often, but not always, seen with increased PEEP and after lung recruitment using high airway pressures. The mechanism is that lung areas that were previously not filled with gas or ventilated open up, which means that more of the lungs are ventilated, leading to better compliance and less shunt. This is the logic when the need for increased FiO₂ is connected to the use of higher PEEP (PEEP-FiO₂ tables).

At the same time, we have also locally experienced that the combination of severe ARDS (low PaO₂/FiO₂ ratio) and relatively high (almost normal) compliance is relatively common. However, this is also observed in ARDS of other etiologies than COVID-19. For all patients with ARDS, regardless of etiology, the choice of treatment, such as ventilator settings, must be continuously adapted to the current situation. An example of this is when severe oxygenation problems (low PaO₂/FiO₂) are associated with well-preserved, almost normal, compliance. Well-preserved compliance indicates that the low PaO₂/FiO₂ is not explained by lung areas without ventilation , which means that there is less potential for higher PEEP to improve gas exchange or compliance. Well-preserved compliance and the absence of large lung areas that are not filled with gas or ventilated are consistent with the radiological findings commonly seen in COVID-19 pneumonia: ground-glass type infiltrates and the absence of larger consolidated lung areas.

The oxygenation issue in this situation has instead been suggested to result from V/Q mismatch combined with impaired hypoxic vasoconstriction. In this situation, slightly lower PEEP and slightly higher tidal volumes become reasonable. High PEEP can worsen gas exchange, especially CO₂ elimination, through several mechanisms. This is not specific to COVID-19 patients, but it becomes particularly important as PEEP seems less likely to open unventilated lung areas. The deterioration in gas exchange with increased PEEP becomes more pronounced if the patient is relatively hypovolemic. With preserved lung compliance, PEEP has a greater effect on preload than in ARDS with decreased compliance. Deteriorated cardiac output caused by high PEEP and relative hypovolemia has been suggested to contribute to acute kidney failure in COVID-19 patients. Other patients with COVID-19 pneumonia describe a pathophysiology more typical of “regular” ARDS: reduced compliance and shunt due to lung areas that are not filled with gas or ventilated, combined with improved gas exchange with increased PEEP/lung recruitment. In this situation, the indication to limit tidal volume and test higher PEEP is strengthened.

The discussion about different types of ARDS will likely continue. Regardless, the overall experience seems to support greater restraint with higher PEEP and acceptance of higher tidal volumes than in COVID-19 ARDS, but there may also be patients or situations where the pathophysiology more closely resembles “regular” ARDS.

Literature

Overall Information on Covid-19 – With Statistics

Reported cases and deaths per country on Worldometer (scroll down to the table)

Our World in Data: Coronavirus Pandemic (COVID-19)

Statistics from the National Board of Health and Welfare on the number of deaths from Covid-19

John Hopkins Live Global Corona Pandemic Update

Live data via a link from John Hopkins Hospital

Treatment Algorithm for COVID-19 Patient

Click on the image to download the PDF file

Treatment Algorithm for COVID-19 Patient. Continued Treatment

Click on the image to download the PDF file

Infection Specialists Association Video Seminar

Guidelines on the Management of Critically Ill Adults with Coronavirus Disease 2019 (COVID-19)

Click on the image to download the PDF file

Current Evidence for Various Treatment Strategies in Covid-19 Infection

Click on the image to download the PDF file

Recommendations Regarding COVID-19 Patients Requiring Intensive Care

Click on the link to download the PDF file

Airway Management in COVID-19 Patients

Click on the image to download the PDF file

Intubation of Covid-19 Patient (link to video)

Protective Equipment

All healthcare personnel caring for patients with COVID-19 should follow local and national guidelines for the care of infected patients and use the protective equipment recommended for treating COVID-19 infected individuals.

Click on the link to download the PDF file

SFAI’s recommendations for protective measures in the care of Corona patients