Prone position ventilation can help improve the prognosis of COVID-19 patients with moderate to severe acute respiratory distress syndrome who require tracheal intubation, but its impact in awake, non-tracheally intubated COVID-19 patients is uncertain. Recently, a systematic review and meta-analysis published in BMJ suggested that prone position ventilation can also significantly reduce the risk of tracheal intubation in awake COVID-19 patients, but has no significant impact on other secondary endpoints such as mortality and ICU hospital stay.
Is ventilation in prone position also suitable for awake patients?
For patients with moderate to severe acute respiratory distress syndrome (ARDS) who receive tracheal intubation and mechanical ventilation, prone positioning can help reduce ventilation/blood flow heterogeneity, increase alveolar ventilation in the gravity-dependent area near the diaphragm, and increase airway secretion drainage. Domestic and foreign studies have clarified the important role of prone position ventilation in the treatment of patients with moderate to severe ARDS. It can effectively improve patient oxygenation, shorten intensive care unit (ICU) hospitalization time and mechanical ventilation time, and reduce 28-day and 90-day mortality.
Therefore, the "Surviving Sepsis Campaign: Management Guidelines for Adult Severe COVID-19 Patients" released in 2020 recommends that patients with critical COVID-19 can use prone position ventilation for 12 to 16 hours a day.
Although there is high-certainty evidence that prone positioning helps improve outcomes in patients with moderate to severe ARDS COVID-19 who are receiving invasive ventilation, it is not clear whether prone ventilation has a positive effect on patients with COVID-19. Whether conscious COVID-19 patients who are mainly breathing and not intubated can also benefit? Studies have shown that for conscious COVID-19 patients who receive nasal high-flow oxygen therapy and non-invasive ventilation, prone position ventilation can also improve oxygenation and reduce respiratory effort, helping to reduce the risk of spontaneous lung injury.
A systematic review and meta-analysis published in "British Medical Journal" (BMJ) in December 2022, including 17 studies and 2931 cases of hypoxic respiratory failure and non-intubation Treating conscious COVID-19 patients (12 of which had low risk of bias and 5 had varying degrees of risk of bias), the primary outcome of the study was tracheal intubation, and the secondary outcomes were death, ventilator-free days, ICU length of stay, oxygen therapy mode upgrades, changes in oxygenation and respiratory rate, and adverse events.
The results of the study show that the tracheal intubation rates of patients with awake prone position ventilation and conventional treatment are 24.2% and 29.8% respectively. The risk of intubation was reduced by 17% (relative risk: 0.83, 95% CI: 0.73 to 0.94; high certainty), which is equivalent to 55 fewer intubations per 1000 patients (95% CI: 87 to 19 times).
However, prone positioning ventilation had no significant impact on other secondary outcomes, with mortality rates of 15.6% and 17.2% in patients on awake prone positioning ventilation and conventional care, respectively (relative risk 0.90, 95% CI: 0.76 to 1.07; high certainty), and the difference in ventilator-free days was 0.97 days (95% CI: -0.5) ~3.4; low certainty), the difference in ICU length of stay was -2.1 days (95% CI: -4.5 to 0.4 days; low certainty), and the difference in length of stay was -0.09 days (95% CI: -0. 69 to 0.51 days; moderate certainty), and the incidence rates of oxygen therapy mode upgrade were 21.4% and 23.0% respectively (relative risk 1.04, 95% CI: 0.74 to 1.44; low certainty).
Adverse events related to awake prone positioning are uncommon.
Bayesian meta-analysis showed that tracheal intubation in the awake prone position has a high probability of benefit (mean relative risk 0.83, 95% CI: 0.70 to 0. 97; the posterior probability of relative risk <0.95>
Results of this systematic review and meta-analysis show that compared with usual care, awake prone positioning is associated with a reduced risk of tracheal intubation in adults with hypoxic respiratory failure due to COVID-19. On average, 55 intubations can be reduced per 1,000 patients. However, awake prone position ventilation had little impact on secondary outcomes such as death, ventilator-free days, ICU length of stay, and oxygen therapy mode upgrades.
The researchers noted that the mechanism by which awake prone ventilation reduces endotracheal intubation remains uncertain. They believe that longer periods of prone ventilation may be a key factor affecting outcome. In the subgroup analysis of this study, patients with prone position ventilation for ≥5 hours had a more significant benefit (RR 0.78), while patients with prone position ventilation for <5>
Unlike awake patients, intubated patients often require sedation and longer ventilation times in the prone position. The researchers believe that the length of ventilation may also have an important impact on secondary outcomes such as mortality.
Prone position ventilation, how to do it?
Critically ill patients often involve complicated conditions such as artificial airways, monitoring catheters, intravenous catheters, ECMO catheters, drainage catheters, etc. Before ventilating in the prone position, sufficient assessment and preparation are required. The specific operating procedures for prone position ventilation can be referred to the "Practical Procedure for Prone Position Ventilation for Patients with Critically Severe New Coronavirus Pneumonia" developed by the Critical Respiratory Medicine Group of the Critical Care Medicine Branch of the Chinese Medical Association.
△Prone position safety assessment process for mechanically ventilated patients with severe new coronavirus pneumonia
△Prone position implementation flow chart for mechanically ventilated patients with severe new coronavirus pneumonia
For awake COVID-19 patients, prone position ventilation is relatively simple. We can put a pillow on the chest and abdomen to maintain a comfortable prone position. To make yourself lie down comfortably without holding your breath, try to lie down for a long enough time. As mentioned above, it should be at least ≥5 hours/day. However, these ≥5 hours can be divided into 3 to 4 times, which means lying down for 1 to 2 hours each time.
Similarly, patients with the following conditions need to use prone position ventilation with caution:
, severe hemodynamic instability;
, intracranial hypertension;
3, active bleeding ;
4, cervical vertebra and spinal injuries requiring immobilization;
5, unfixed fracture;
6, restricted position after orthopedic surgery;
7. Recent abdominal surgery requires position restriction or severe abdominal burns..;
8. Pregnancy;
9. Postoperative facial trauma;
0. Inability to tolerate the prone position;
1. Patients with venous thrombosis ;
2. Patients with prone position whose blood oxygen index worsens;
3. Patients with arrhythmia who have a pacemaker placed;
Is it safe to ventilate in the prone position?
Under normal circumstances, awake prone ventilation is safe and adverse events are rare. Common adverse events include catheter migration, discomfort, nausea, and skin breakdown.
For example, in the systematic review and meta-analysis mentioned above, the most frequently reported adverse events in awake prone ventilation patients (n=1469) were catheter dislodgement (2.5%), pain or discomfort (2%), nausea and vomiting (1.2%), and skin breakdown or pressure ulcers (0.7%).
Mechanically ventilated patients are at a higher risk of serious complications during prone positioning, including displacement or detachment of the artificial airway and acute circulatory failure ( cardiac arrest caused by various causes). Common causes include: as the body position changes, medical facilities, breathing tubes and drainage tubes may shift due to traction; improper fixation, displacement and detachment of the catheter caused by gravity, etc. If the artificial airway shifts or falls off when prone, it will be difficult to replace it in a short time; and first aid operations such as cardiopulmonary resuscitation (CPR) cannot be effectively performed in the prone position. In addition, ventilating in the prone position for more than 12 hours may cause skin pressure sores in the pressure areas, and improper positioning of shoulders and upper limbs may cause nerve damage.
▌Reference:
[1]Jason Weatherald, et al.Efficacy of awake prone positioning in patients with covid-19 related hypoxemic respiratory failure: systematic review and meta-analysis of randomized trials.BMJ 2022;379:e071966.doi: https://doi.org/10.1136/bmj-2022-071966
[2]AlhazzaniW, MøllerMH, ArabiYM, et al. Surviving Sepsis Campaign: guidelines on the management of critically ill adults with coronavirus disease 2019 (COVID-19) [J]. Crit Care Med, 2020, 48 (6): e440-e469. DOI: 10.1097/CCM.0000000000004363.
[3]Xu Yan, Meng Mei, Liu Jiao, et al. Practical procedure of prone position ventilation for patients with severe new coronavirus pneumonia [J]. Chinese Critical Care Medicine, 2021, 33(4): 393-398. DOI: 10.3760/cma.j.cn121430-20210224-00112.
