Hypoxemia occurs when levels of oxygen in the blood are lower than normal. If blood oxygen levels are too low, your body may not work properly. Blood carries oxygen to the cells throughout your body to keep them healthy. Hypoxemia can cause mild problems such as headaches and shortness of breath. Healthy lungs keep the blood oxygenated at a level between 95 and 100%—if it dips below 92%, it’s a cause for concern and a doctor might decide to intervene with supplemental oxygen. Scientific Proofs - Oxygen Levels Decreases During Apneas. Even the most recent studies (2012) demonstrates the link between sleep apnea and oxygen desaturation. That's why the oximeter is an important tool in clinical assessment. With a finger pulse oximeter you can monitor yourself to see how effective is CPAP (you'll learn how to do this bellow).

Oxygen levels and Covid-19

Vital signs, those fluorescent green numbers that beep, ding, and dash across black screens on the monitors in hospital rooms, have become a new source of angst during the coronavirus pandemic.

One of those vital signs is blood oxygen level, and in the hospital, it's measured with a pulse oximeter. These devices are attached to your finger and use a beam of light to measure oxygen in the blood.

Patients with Covid-19 can sometimes have relatively mild symptoms and seem to be perfectly oxygenated, even while their blood oxygen levels are perilously low. As a result, they may need an emergency supply of supplemental oxygen.

Covid-19 patients healthy enough to be discharged are often sent home with instructions to self-monitor, which has triggered a demand for pulse oximeters you can buy and use at home.

The tiny devices, which range in price from $20 to $200, clamp snugly over the index finger and display the percentage of oxygen being carried around by your blood. But how accurate are they? And how do you read them?

Three doctors, all of whom were on the coronavirus frontlines during the first peak in hard-hit New York City, warn that the results and efficacy can differ from unit to unit.

The Food and Drug Administration (FDA) considers pulse oximeters to be prescription medical devices, but most of those sold on the internet or in drugstores are labeled 'not for medical use' and have not been reviewed for accuracy. Still, having a pulse oximeter on hand may come in handy, as long as users exert common sense.

Consumers should use the devices while under a physician's care and follow up if blood oxygen readings seem to dip precipitously, especially when paired with symptoms like shortness of breath, cough, and fever.

Here's what you need to know about checking oxygen levels with a pulse oximeter at home.

Understanding normal oxygen levels

The average person takes about 20,000 breaths a day. Keeping normal oxygen levels is a finely-tuned science.

'We've got to get oxygen from the atmosphere into our lungs; we've got to get the oxygen from our lungs into our bloodstream, and then we've got to get the blood to our cells, and our cells have to take out that oxygen. So, all those things have to work right for things to go well,' explains Amit Uppal, MD, director of critical care at Bellevue Hospital in New York City.

To date, Dr. Uppal says he's overseen the treatment of more than 300 Covid-19 patients, all with varying levels of blood oxygen.

What is a good oxygen level?

'Normal people who have working lungs, and all those steps are going well, their blood oxygen level will usually be 96-100 percent,' adds Dr. Uppal.

A few notches down at 94 percent, he says, will be considered 'abnormal,' but that won't necessarily be cause for alarm. 'For the vast majority of people, nothing bad will happen. Nobody's going to have a cardiac arrest with a blood oxygen level in that [94] range.'

If someone has heart or lung disease, says Dr. Uppal, those 'normal' numbers may be a bit lower. There is, however, a universal threshold that signifies a dangerous situation.

'I think anything below 90 we definitely get very concerned. When it gets down into the 80 percent range or less than 80 percent range is when really bad things can happen.'

There is a possibility an individual's oxygen levels can be too high. However, this often occurs in people who are on supplemental oxygen.

High levels can be measured via an arterial blood gas (ABG) test, which is accurate, but invasive. This is a blood test that requires blood to be drawn from the artery, which is usually done in the wrist.

This measures your blood oxygen level and can also detect other gas levels in the blood, as well as your pH, or how acidic your blood is.

What happens when blood oxygen dips too low

When your blood oxygen reading falls below that 90 percent threshold, you'll likely feel a variety of symptoms.

'It includes feeling short of breath, and increased respiratory rate. So, if you're at rest and noticing that you're having to work hard to breathe, that's a sign,' says Reed Caldwell, MD, chief of service at NYU Langone's Cobble Hill emergency department.

You could also experience cyanosis, meaning you could turn blue or gray due to the blood's poor oxygenation, or you might have confusion, adds Dr. Caldwell.

'Your brain thrives on oxygen,' says Dr. Caldwell. 'So, people can be confused—or even unconscious.'

One of the more concerning Covid-19 symptoms

Infectious disease epidemiologist Syra Madad studied and led response teams during some of this generation's most serious health crises including Ebola, Zika, and measles. But she says nothing frightens her more than Covid-19.

'From my standpoint, and all the different epidemics I've responded to, this has been something I have never seen before,' says Madad, who is the senior director of the system-wide special pathogens program at New York City Health + Hospitals.

Last fall, she asked Congress not to let a pandemic-protection bill lapse and is now dealing with the fallout as the U.S. currently has 500,000-plus deaths from Covid-19 and counting. (It's documented in a new Netflix documentary, Pandemic: How to Prevent an Outbreak, featuring Madad.)

'Some people will be perfectly fine and have no issues,' says Madad. 'And other people will come in with their oxygen saturation levels below 94, 93, 92 percent, or even lower than that. And they look perfectly fine. It's one of those silent hypoxic killers almost.'

What is hypoxemia?

When someone is hypoxic, they're experiencing hypoxia or the absence of enough oxygen inside the body's tissues to sustain bodily functions. (A similar term, hypoxemia, means low oxygen levels in the blood, rather than the body's tissues.)

Covid-19 patients with this sign have been dubbed as having 'happy hypoxia.'

Instead of gasping for air, they're texting on their smartphones. 'They're not showing the signs and symptoms like bluish lips, trouble breathing, anything like that,' says Madad. 'So you have no idea they're experiencing this symptom, and then you check their blood oxygen levels, and you realize they're at very alarmingly low levels.'

In a June article in the Journal of Medical Systems, author Jason Teo further explained how silent hypoxia sneaks up on people.

'The air sacs in Covid-19 patients' lungs do not fill with fluid or pus as in normal pneumonia infections but rather the virus only causes the air sacs to collapse, thereby reducing the oxygen levels that lead to hypoxia in these patients but still maintains the lungs' normal ability to expel carbon dioxide,' wrote Teo.

He proposes that smartphone-based oximeters may one day unlock the key to more widespread early detection.

How to check blood oxygen using a pulse oximeter

Although they were scarce early in the pandemic, pulse oximeters are now easy to find. (An Amazon search returns 1,000 results.) Many are battery-powered and simply need to be turned on and placed on your index finger.

Pulse oximeters display two readings—one is SpO2, which is the oxygen saturation level in your blood, and your pulse rate.

'Monitoring [with an oximeter] is OK as long as you're under the guidance of a medical physician,' says Dr. Caldwell. 'I think it could be a potentially disastrous situation to be in if people take it upon themselves to just look up the numbers on the internet and then monitor their oxygen.'

Also, warns Dr. Uppal: 'I don't think that the general public of people who have no symptoms and have not tested positive for Covid-19 need to be checking their pulse oxygen 10 times a day.'

When to call a doctor

Early intervention could improve health outcomes for patients presenting with lowered blood oxygen. People with low oxygen levels will often require supplemental oxygen to increase their oxygen saturation.

'We know that some people are still kind of avoidant of health care because they are afraid to get Covid-19,' says Dr. Caldwell. 'And if you can't breathe, you need to be seen. And if your oxygen level is low, you need to be evaluated because your chances of a bad outcome trying to manage [while] stuck at home, it still needs to outweigh your chance of your family picking up something in a health care setting.'

Or, someone could have something other than Covid-19 altogether. 'A blood clot in your lung can give you low oxygen' notes Dr. Caldwell, 'that's something that would need prompt attention.'

Now, doctors may also suggest home supplemental oxygen, which is prescribed. Your doctor will provide specific instructions for using home supplemental oxygen to prevent any serious complications.

Preventing Covid-19

Dr. Uppal says he has had the fortune of helping some of his Covid-19-patients recover and the misfortune of saying goodbye to others. This includes longtime colleagues for whom he fought hard for.

A particularly heart-wrenching case, he remembers, was a mother and father who passed away due to Covid-19, orphaning their two young children.

Today, nearly an entire year into the pandemic, Dr. Uppal says there are far more tools in physicians' toolbox to fight back against respiratory diseases like Covid-19.

'Steroids seem to help patients who start to deteriorate. It seems to reduce the likelihood that they end up on a breathing machine or reduce the likelihood that they end up in the ICU,' Dr. Uppal says. 'Remdesivir seems to help reduce the severity in patients. And some data just came out that a drug called tocilizumab also is beneficial.'

But nothing used to treat Covid-19 is as useful as taking measures to prevent it.

'I think what I'd like to emphasize is that getting better at treating the disease once people have it doesn't make it go away.' Dr. Uppal adds, 'The thing that we're still going to have to lean on is preventing it from spreading in the first place.'

The post What Is a Normal Oxygen Level and How Can I Check Mine? appeared first on The Healthy.

Last Updated: December 17, 2020

The COVID-19 Treatment Guidelines Panel’s (the Panel’s) recommendations below emphasize recommendations from the Surviving Sepsis Campaign Guidelines for adult sepsis, pediatric sepsis, and COVID-19.

Nonmechanically Ventilated Adults With Hypoxemic Respiratory Failure

Recommendations

• For adults with COVID-19 and acute hypoxemic respiratory failure despite conventional oxygen therapy, the Panel recommends high-flow nasal cannula (HFNC) oxygen over noninvasive positive pressure ventilation (NIPPV) (BIIa).
• In the absence of an indication for endotracheal intubation, the Panel recommends a closely monitored trial of NIPPV for adults with COVID-19 and acute hypoxemic respiratory failure and for whom HFNC is not available (BIIa).
• For patients with persistent hypoxemia despite increasing supplemental oxygen requirements in whom endotracheal intubation is not otherwise indicated, the Panel recommends considering a trial of awake prone positioning to improve oxygenation (CIIa).
• The Panel recommends against using awake prone positioning as a rescue therapy for refractory hypoxemia to avoid intubation in patients who otherwise meet the indications for intubation and mechanical ventilation (AIII).
• If intubation becomes necessary, the procedure should be performed by an experienced practitioner in a controlled setting due to the enhanced risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure to health care practitioners during intubation (AIII).

Rationale

Severe illness in COVID-19 typically occurs approximately 1 week after the onset of symptoms. The most common symptom is dyspnea, which is often accompanied by hypoxemia. Patients with severe disease typically require supplemental oxygen and should be monitored closely for worsening respiratory status because some patients may progress to acute respiratory distress syndrome (ARDS).

Goal of Oxygenation

The optimal oxygen saturation (SpO₂) in adults with COVID-19 is uncertain. However, a target SpO2 of 92% to 96% seems logical considering that indirect evidence from experience in patients without COVID-19 suggests that an SpO2 <92% or >96% may be harmful.

Regarding the potential harm of maintaining an SpO2 <92%, a trial randomly assigned ARDS patients without COVID-19 to either a conservative oxygen strategy (target SpO2 of 88% to 92%) or a liberal oxygen strategy (target SpO2 ≥96%). The trial was stopped early due to futility after enrolling 205 patients, but in the conservative oxygen group there was increased mortality at 90 days (between-group risk difference of 14%; 95% CI, 0.7% to 27%) and a trend toward increased mortality at 28-days (between-group risk difference of 8%; 95% CI, -5% to 21%).¹

Regarding the potential harm of maintaining an SpO2 >96%, a meta-analysis of 25 randomized trials involving patients without COVID-19 found that a liberal oxygen strategy (median SpO2 of 96%) was associated with an increased risk of in-hospital mortality compared to a lower SpO2 comparator (relative risk 1.21; 95% CI, 1.03–1.43).²

Acute Hypoxemic Respiratory Failure

In adults with COVID-19 and acute hypoxemic respiratory failure, conventional oxygen therapy may be insufficient to meet the oxygen needs of the patient. Options for providing enhanced respiratory support include HFNC, NIPPV, intubation and invasive mechanical ventilation, or extracorporeal membrane oxygenation (ECMO).

High-Flow Nasal Cannula and Noninvasive Positive Pressure Ventilation

HFNC is preferred over NIPPV in patients with acute hypoxemic respiratory failure based on data from an unblinded clinical trial in patients without COVID-19 who had acute hypoxemic respiratory failure. Study participants were randomized to HFNC, conventional oxygen therapy, or NIPPV. The patients in the HFNC group had more ventilator-free days (24 days) than those in the conventional oxygen therapy group (22 days) or NIPPV group (19 days) (P = 0.02), and 90-day mortality was lower in the HFNC group than in either the conventional oxygen therapy group (HR 2.01; 95% CI, 1.01–3.99) or the NIPPV group (HR 2.50; 95% CI, 1.31–4.78).³ In the subgroup of more severely hypoxemic patients (PaO₂/FiO₂ mm Hg ≤200), the intubation rate was lower for HFNC than for conventional oxygen therapy or NIPPV (HR 2.07 and 2.57, respectively).

The trial’s findings were corroborated by a meta-analysis of eight trials with 1,084 patients conducted to assess the effectiveness of oxygenation strategies prior to intubation. Compared to NIPPV, HFNC reduced the rate of intubation (OR 0.48; 95% CI, 0.31–0.73) and ICU mortality (OR 0.36; 95% CI, 0.20–0.63).⁴

NIPPV may generate aerosol spread of SARS-CoV-2 and thus increase nosocomial transmission of the infection.^5,6 It remains unclear whether HFNC results in a lower risk of nosocomial SARS-CoV-2 transmission than NIPPV.

Prone Positioning for Nonintubated Patients

Although prone positioning has been shown to improve oxygenation and outcomes in patients with moderate-to-severe ARDS who are receiving mechanical ventilation,^7,8 there is less evidence regarding the benefit of prone positioning in awake patients who require supplemental oxygen without mechanical ventilation. In a case series of 50 patients with COVID-19 pneumonia who required supplemental oxygen upon presentation to a New York City emergency department, awake prone positioning improved the overall median oxygen saturation of the patients. However, 13 patients still required intubation due to respiratory failure within 24 hours of presentation to the emergency department.⁹ Other case series of patients with COVID-19 requiring oxygen or NIPPV have similarly reported that awake prone positioning is well-tolerated and improves oxygenation,^10-12 with some series also reporting low intubation rates after proning.^10,12

A prospective feasibility study of awake prone positioning in 56 patients with COVID-19 receiving HFNC or NIPPV in a single Italian hospital found that prone positioning for ≤3 hours was feasible in 84% of the patients. There was a significant improvement in oxygenation during prone positioning (PaO₂/FiO₂ 181 mm Hg in supine position vs. PaO₂/FiO₂ 286 mm Hg in prone position). However, when compared with baseline oxygenation before initiation of prone positioning, this improvement in oxygenation was not sustained (PaO₂/FiO₂ of 181 mm Hg and 192 mm Hg at baseline and 1 hour after resupination, respectively). Among patients put in the prone position, there was no difference in intubation rate between patients who maintained improved oxygenation (i.e., responders) and nonresponders.⁹

A prospective, multicenter observational cohort study in Spain and Andorra evaluated the effect of prone positioning on the rate of intubation in COVID-19 patients with acute respiratory failure receiving HFNC. Of the 199 patients requiring HFNC, 55 (27.6%) were treated with prone positioning. Although the time to intubation was 1 day (IQR 1.0–2.5) in patients receiving HFNC and prone positioning versus 2 days [IQR 1.0–3.0] in patients receiving only HFNC (P = 0.055), the use of awake prone positioning did not reduce the risk of intubation (RR 0.87; 95% CI, 0.53–1.43; P = 0.60).¹³

Overall, despite promising data, it is unclear which hypoxemic, nonintubated patients with COVID-19 pneumonia benefit from prone positioning, how long prone positioning should be continued, or whether the technique prevents the need for intubation or improves survival.¹⁰

Appropriate candidates for awake prone positioning are those who can adjust their position independently and tolerate lying prone. Awake prone positioning is contraindicated in patients who are in respiratory distress and who require immediate intubation. Awake prone positioning is also contraindicated in patients who are hemodynamically unstable, patients who recently had abdominal surgery, and patients who have an unstable spine.¹⁴ Awake prone positioning is acceptable and feasible for pregnant patients and can be performed in the left lateral decubitus position or the fully prone position.¹⁵

Intubation for Invasive Mechanical Ventilation

It is essential to monitor hypoxemic patients with COVID-19 closely for signs of respiratory decompensation. To ensure the safety of both patients and health care workers, intubation should be performed in a controlled setting by an experienced practitioner.

Mechanically Ventilated Adults

Recommendations

For mechanically ventilated adults with COVID-19 and ARDS:

• The Panel recommends using low tidal volume (VT) ventilation (VT 4–8 mL/kg of predicted body weight) over higher VT ventilation (VT >8 mL/kg) (AI).
• The Panel recommends targeting plateau pressures of <30 cm H₂O (AIIa).
• The Panel recommends using a conservative fluid strategy over a liberal fluid strategy (BIIa).
• The Panel recommends against the routine use of inhaled nitric oxide (AIIa).

Rationale

There is no evidence that ventilator management of patients with hypoxemic respiratory failure due to COVID-19 should differ from ventilator management of patients with hypoxemic respiratory failure due to other causes.

Positive End-Expiratory Pressure and Prone Positioning in Mechanically Ventilated Adults With Moderate to Severe Acute Respiratory Distress Syndrome

Recommendations

For mechanically ventilated adults with COVID-19 and moderate-to-severe ARDS:

• The Panel recommends using a higher positive end-expiratory pressure (PEEP) strategy over a lower PEEP strategy (BIIa).
• For mechanically ventilated adults with COVID-19 and refractory hypoxemia despite optimized ventilation, the Panel recommends prone ventilation for 12 to 16 hours per day over no prone ventilation (BIIa).

Rationale

PEEP is beneficial in patients with ARDS because it prevents alveolar collapse, improves oxygenation, and minimizes atelectotrauma, a source of ventilator-induced lung injury. A meta-analysis of individual patient data from the three largest trials that compared lower and higher levels of PEEP in patients without COVID-19 found lower rates of ICU mortality and in-hospital mortality with higher PEEP in those with moderate (PaO₂/FiO₂ 100–200 mm Hg) and severe ARDS (PaO₂/FiO₂ <100 mm Hg).¹⁶

Although there is no clear standard as to what constitutes a high level of PEEP, one conventional threshold is >10 cm H₂O.¹⁷ Recent reports have suggested that, in contrast to patients with non-COVID-19 causes of ARDS, some patients with moderate or severe ARDS due to COVID-19 have normal static lung compliance and thus, in these patients, higher PEEP levels may cause harm by compromising hemodynamics and cardiovascular performance.^18,19 Other studies reported that patients with moderate to severe ARDS due to COVID-19 had low compliance, similar to the lung compliance seen in patients with conventional ARDS.^20-23 These seemingly contradictory observations suggest that COVID-19 patients with ARDS are a heterogeneous population and assessment for responsiveness to higher PEEP should be individualized based on oxygenation and lung compliance. Clinicians should monitor patients for known side effects of higher PEEP, such as barotrauma and hypotension.

Neuromuscular Blockade in Mechanically Ventilated Adults With Moderate to Severe Acute Respiratory Distress Syndrome

Recommendations

For mechanically ventilated adults with COVID-19 and moderate-to-severe ARDS:

• The Panel recommends using, as needed, intermittent boluses of neuromuscular blocking agents (NMBA) or continuous NMBA infusion to facilitate protective lung ventilation (BIIa).
• In the event of persistent patient-ventilator dyssynchrony, or in cases where a patient requires ongoing deep sedation, prone ventilation, or persistently high plateau pressures, the Panel recommends using a continuous NMBA infusion for up to 48 hours as long as patient anxiety and pain can be adequately monitored and controlled (BIII).

96 Oxygen Level Baby

Rationale

The recommendation for intermittent boluses of NMBA or continuous infusion of NMBA to facilitate lung protection may require a health care provider to enter the patient’s room frequently for close clinical monitoring. Therefore, in some situations, the risks of SARS-CoV-2 exposure and the need to use personal protective equipment for each entry into a patient’s room may outweigh the benefit of NMBA treatment.

Rescue Therapies for Mechanically Ventilated Adults With Acute Respiratory Distress Syndrome

Recommendations

96 Oxygen Level Normal

For mechanically ventilated adults with COVID-19, severe ARDS, and hypoxemia despite optimized ventilation and other rescue strategies:

96 Oxygen Level Good

• The Panel recommends using recruitment maneuvers rather than not using recruitment maneuvers (CIIa).
• If recruitment maneuvers are used, the Panel recommends against using staircase (incremental PEEP) recruitment maneuvers (AIIa).
• The Panel recommends using an inhaled pulmonary vasodilator as a rescue therapy; if no rapid improvement in oxygenation is observed, the treatment should be tapered off (CIII).

96 Oxygen Level Child

Rationale

There are no studies to date assessing the effect of recruitment maneuvers on oxygenation in severe ARDS due to COVID-19. However, a systematic review and meta-analysis of six trials of recruitment maneuvers in non-COVID-19 patients with ARDS found that recruitment maneuvers reduced mortality, improved oxygenation 24 hours after the maneuver, and decreased the need for rescue therapy.²⁴ Because recruitment maneuvers can cause barotrauma or hypotension, patients should be closely monitored during recruitment maneuvers. If a patient decompensates during recruitment maneuvers, the maneuver should be stopped immediately. The importance of properly performing recruitment maneuvers was illustrated by an analysis of eight randomized controlled trials in non-COVID-19 patients (n = 2,544) which found that recruitment maneuvers did not reduce hospital mortality (RR 0.90; 95% CI, 0.78–1.04). Subgroup analysis found that traditional recruitment maneuvers significantly reduced hospital mortality (RR 0.85; 95% CI, 0.75–0.97), whereas incremental PEEP titration recruitment maneuvers increased mortality (RR 1.06; 95% CI, 0.97–1.17).²⁵

Although there are no published studies of inhaled nitric oxide in patients with COVID-19, a Cochrane review of 13 trials of inhaled nitric oxide use in patients with ARDS found no mortality benefit.²⁶ Because the review showed a transient benefit in oxygenation, it is reasonable to attempt inhaled nitric oxide as a rescue therapy in COVID patients with severe ARDS after other options have failed. However, if there is no benefit in oxygenation with inhaled nitric oxide, it should be tapered quickly to avoid rebound pulmonary vasoconstriction that may occur with discontinuation after prolonged use.

References

1. Barrot L, Asfar P, Mauny F, et al. Liberal or conservative oxygen therapy for acute respiratory distress syndrome. N Engl J Med. 2020;382(11):999-1008. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32160661.
2. Chu DK, Kim LH, Young PJ, et al. Mortality and morbidity in acutely ill adults treated with liberal versus conservative oxygen therapy (IOTA): a systematic review and meta-analysis. Lancet. 2018;391(10131):1693-1705. Available at: https://www.ncbi.nlm.nih.gov/pubmed/29726345.
3. Frat JP, Thille AW, Mercat A, et al. High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med. 2015;372(23):2185-2196. Available at: https://www.ncbi.nlm.nih.gov/pubmed/25981908.
4. Ni YN, Luo J, Yu H, Liu D, Liang BM, Liang ZA. The effect of high-flow nasal cannula in reducing the mortality and the rate of endotracheal intubation when used before mechanical ventilation compared with conventional oxygen therapy and noninvasive positive pressure ventilation. A systematic review and meta-analysis. Am J Emerg Med. 2018;36(2):226-233. Available at: https://www.ncbi.nlm.nih.gov/pubmed/28780231.
5. Tran K, Cimon K, Severn M, Pessoa-Silva CL, Conly J. Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: a systematic review. PLoS One. 2012;7(4):e35797. Available at: https://www.ncbi.nlm.nih.gov/pubmed/22563403.
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11. Elharrar X, Trigui Y, Dols AM, et al. Use of prone positioning in nonintubated patients With COVID-19 and hypoxemic acute respiratory failure. JAMA. 2020;323(22):2336-2338. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32412581.
12. Sartini C, Tresoldi M, Scarpellini P, et al. Respiratory parameters in patients with COVID-19 after using noninvasive ventilation in the prone position outside the intensive care unit. JAMA. 2020;323(22):2338-2340. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32412606.
13. Ferrando C, Mellado-Artigas R, Gea A, et al. Awake prone positioning does not reduce the risk of intubation in COVID-19 treated with high-flow nasal oxygen therapy: a multicenter, adjusted cohort study. Crit Care. 2020;24(1):597. Available at: https://www.ncbi.nlm.nih.gov/pubmed/33023669.
14. Bamford P, Bentley A, Dean J, Whitmore D, Wilson-Baig N. ICS guidance for prone positioning of the conscious COVID patient. Intensive Care Society. 2020. Available at: https://emcrit.org/wp-content/uploads/2020/04/2020-04-12-Guidance-for-conscious-proning.pdf. Accessed December 8, 2020.
15. Society for Maternal Fetal Medicine. Management considerations for pregnant patients with COVID-19. 2020. Available at: https://s3.amazonaws.com/cdn.smfm.org/media/2336/SMFM_COVID_Management_of_COVID_pos_preg_patients_4-30-20_final.pdf. Accessed December 8, 2020.
16. Briel M, Meade M, Mercat A, et al. Higher vs. lower positive end-expiratory pressure in patients with acute lung injury and acute respiratory distress syndrome: systematic review and meta-analysis. JAMA. 2010;303(9):865-873. Available at: https://www.ncbi.nlm.nih.gov/pubmed/20197533.
17. Alhazzani W, Moller MH, Arabi YM, et al. Surviving Sepsis Campaign: guidelines on the management of critically ill adults with coronavirus disease 2019 (COVID-19). Crit Care Med. 2020;48(6):e440-e469. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32224769.
18. Marini JJ, Gattinoni L. Management of COVID-19 respiratory distress. JAMA. 2020;323(22):2329-2330. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32329799.
19. Tsolaki V, Siempos I, Magira E, Kokkoris S, Zakynthinos GE, Zakynthinos S. PEEP levels in COVID-19 pneumonia. Crit Care. 2020;24(1):303. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32505186.
20. Bhatraju PK, Ghassemieh BJ, Nichols M, et al. COVID-19 in critically ill patients in the Seattle region - case series. N Engl J Med. 2020;382(21):2012-2022. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32227758.
21. Cummings MJ, Baldwin MR, Abrams D, et al. Epidemiology, clinical course, and outcomes of critically ill adults with COVID-19 in New York City: a prospective cohort study. Lancet. 2020;395(10239):1763-1770. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32442528.
22. Ziehr DR, Alladina J, Petri CR, et al. Respiratory pathophysiology of mechanically ventilated patients with COVID-19: a cohort study. Am JRespir Crit Care Med. 2020;201(12):1560-1564. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32348678.
23. Schenck EJ, Hoffman K, Goyal P, et al. Respiratory mechanics and gas exchange in COVID-19 associated respiratory failure. Ann Am Thorac Soc. 2020;17(9):1158-1161. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32432896.
24. Goligher EC, Hodgson CL, Adhikari NKJ, et al. Lung recruitment maneuvers for adult patients with acute respiratory distress syndrome. a systematic review and meta-analysis. Ann Am Thorac Soc. 2017;14(Supplement 4):S304-S311. Available at: https://www.ncbi.nlm.nih.gov/pubmed/29043837.
25. Alhazzani W, Moller MH, Arabi YM, et al. Surviving Sepsis Campaign: guidelines on the management of critically ill adults with Coronavirus Disease 2019 (COVID-19). Intensive Care Med. 2020;46(5):854-887. Available at: https://www.ncbi.nlm.nih.gov/pubmed/32222812.
26. Gebistorf F, Karam O, Wetterslev J, Afshari A. Inhaled nitric oxide for acute respiratory distress syndrome (ARDS) in children and adults. Cochrane Database Syst Rev. 2016(6):CD002787. Available at: https://www.ncbi.nlm.nih.gov/pubmed/27347773.