Hospitalized patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or COVID-19) are at high risk for respiratory failure. Of those who progress to moderate-severe Acute Respiratory Distress Syndrome (ARDS), prone positioning has been shown to improve mortality.1-3
Prone positioning alters chest wall mechanics allowing for a more uniform distribution of tidal volume and improved recruitment. The physiologic effects of proning include reduced lung compression, reduced alveolar hyperinflation and alveolar collapse, and improvement in the ventilation-perfusion ratio.4
To avoid mechanical ventilation in patients with respiratory distress, the use of prone positioning in awake, non-intubated patients has been examined. Proning non-intubated, non-COVID-19 patients, has been shown to improve oxygenation.5-8 In non-intubated, COVID-19 patients, proning has also been shown to improve oxygenation along with mortality rates and intubation rates.8-17 Clinical outcomes are also improved with longer duration of prone positioning.16,18
Prior studies demonstrated variable proning regimens and compliance rates between 27%-67%.18-21 Ibarra et al18 demonstrated a 56% compliance rate with a physician driven protocol. However, there is a gap in the literature regarding awake proning compliance rates and its effect on outcomes. Our first aim was to determine patient compliance with a nursing driven proning protocol in non-intubated awake patients. Our secondary aim was to evaluate outcomes of these non-intubated, COVID-19 positive patients who proned compared to those who did not. We hypothesized that most patients would not comply with the proning time recommended by a nursing driven protocol and, therefore, would not have improved outcomes.
Methods
Subjects
This is an observational, before-after clinical study of 184 COVID-19 positive patients admitted to the same hospital ward at Robert Wood Johnson University Hospital over a period of 4 weeks from April 6, 2020 to May 4, 2020, during the height of the pandemic. The Institutional Review Board approved this study as minimal risk.
All patients had positive COVID-19 polymerase chain reaction (PCR) testing of nasopharyngeal samples during their admission. All included patients were admitted to the same COVID-19 dedicated general medicine ward within the hospital. The first 2 weeks of the testing period were used as a control, and the patients were not asked to prone. During the subsequent 2 weeks, the ward provided a nurse-driven intervention protocol encouraging patients to self-prone for at least twice a day, for at least 2 hours each session, as tolerated. Patients who were on the floor during the second 2 weeks and who agreed to proning were included in the analysis. Education was provided to the nursing staff by the study team regarding the proning protocol. Nurses then provided their assigned patients proning protocol education in the intervention group. Nursing staff documented the duration of each proning session, whether the patient was in a lateral decubitus position or completely prone, and the reason they did not tolerate proning or refused.
The standard approach to treatment for COVID-19 patients who were not in the intervention group included positioning per patient preference (most commonly supine) and supplemental oxygen as needed to treat hypoxia. Patients were also encouraged to use an incentive spirometer 10 times every hour.
Data
Data were abstracted from the electronic medical record system (Allscripts – Sunrise Clinical Manager, Chicago, IL) and input into a specifically designed abstraction form using the secure web-based application, Research Electronic Data Capture (REDCapTM). All abstractors were trained on its utilization. Data collected from the medical record included patient demographics, pre-existing comorbidities, duration proned per episode, and number of proning episodes.
Proning episodes were defined as either fully proned or those in lateral decubitus position, and this was documented. Mean time prone and the total number of proning episodes were calculated for each patient. Compliance with the proning protocol was evaluated and documented in the electronic medical record by the nursing team.
Outcomes of Interest
Primary outcomes in this report include compliance with the encouraged proning protocol assessed by the number of prone episodes per day per patient (either true prone or lateral decubitus) and mean time proned per proning episode per patient. Secondary outcomes include intensive care unit length of stay, intubation rate, in-hospital mortality, and comorbidities such as incidence of super-imposed bacterial pneumonia, bacteremia, acute kidney injury, deep vein thrombosis, pulmonary embolism, and myocardial infarction.
Statistical Analysis
Data analysis was performed using the latest version of R (The R Foundation for Statistical Computing). Normally distributed data were presented as mean ± standard deviation (SD) and compared using the Student’s t-test or with one-way analysis of variance (ANOVA). Results for non-normally distributed variables were presented as median with interquartile range (IQR: 25th-75th percentiles) and were compared by Wilcoxon rank sum test. For participants with missing data, only the available data were used in the analysis. Two-tailed P<0.05 was considered significant.
Results
During the study period, 184 patients who were COVID-19 confirmed positive and admitted to a COVID-19 dedicated general medicine ward were studied. Coincidentally, there were 92 patients in the control group and 92 patients in the proning group. There were more Latino (P=0.005) and Hispanic (P= 0.001) patients in the proning group, but there was no difference in the baseline comorbidities across both groups. The mean age was 62.6 years, 51.1% were female, and there was a predominance of Caucasian (30.8%) patients. Baseline demographics and comorbidities can be seen in Table 1.
Characteristics of COVID-19 Patients Stratified by Proning
There were 514 total proning episodes in the 92-patient prone group over the 2-week intervention period. Of these episodes, 57% were truly proned; whereas 43% of proning episodes were in the lateral decubitus position (Table 2) The mean number of total proning episodes per patient was 6.0 ± 6.1; of those, 3.3 ± 3.5 were true proned vs 2.7 ± 3.8 (P=0.072) lateral decubitus. The time spent per proning episode was similar among those who truly proned vs. those in lateral decubitus position (3.1 ± 2.8 hours vs. 3.7 ± 3.0, P=0.019). The range in duration of proning episodes was from 15 minutes to 15 hours, and the range of number of proning episodes was from 1 to 33. Of the 514 proning episodes, data on the duration per episode was available in 238 episodes (46.3%). Patients proned for over 2-hours in >70% of episodes. During the 324 patient-days on the ward, there were 152 days (47%) where there were two or more proning episodes in a single day.
Summary of Each Proning Episode
Reasons for not proning in individual episodes included patient refusal (n=13, 14%); patient did not tolerate due to hypoxia (n=5, 5%); contraindicated (restrained n=5, peritoneal dialysis n=1); and not documented reasons (n=6, 7%). There was no difference in intensive care unit length of stay (P=0.12), intubation rate (P=0.34), or in-hospital mortality (P=0.46). (Table 3) In addition, awake proning did not improve clinical outcomes such as incidence of pneumonia (P=0.26), bacteremia (P=0.99), AKI (P=0.75), deep vein thrombosis (P=0.32), pulmonary embolism (P=0.31), or new myocardial infarction (P=0.31).
Outcomes of COVID-19 Patients Stratified by Proning
Discussion
This study demonstrates that prone positioning in non-intubated, COVID-19 positive patients admitted to a general medical ward is feasible; however, compliance with true prone positioning is poor. Achieving compliance with a proning protocol in patients who are not intubated is very difficult, even for short periods of time. Despite the median length of stay being 9 days among those who proned in our study, the mean number of proning episodes per patient was only six – fewer than one per day. Additionally, we identified nearly 50% of all proning episodes were in the lateral decubitus position and not truly proned, despite encouraging patients to lie completely prone. While lateral decubitus positioning does not offer the same physiologic benefits that true prone positioning does, it may be a safe alternative for those who cannot tolerate true proning.19,20
With our nursing-encouraged proning regimen of >2 hours per session for more than two episodes per day, we found a 74% and 47% compliance, respectively. In addition, we found fewer patients participated as proning episodes became incrementally longer, with the most patients participating between 2-4 hours per episode, similar to Ehrmann et al.16 In 2013, Guérin et al2 demonstrated that an aggressive proning protocol of >16 hours per session led to improved outcomes in intubated patients with moderate-severe ARDS.2 Similarly, Ibarra et al18 demonstrated improved outcomes with proning episodes for longer than 8 hours per day along with a 56% compliance rate with an at least 16 hour per day proning protocol. A recent meta-analysis by Li et al17 showed benefit with proning only in patients requiring higher levels of oxygen support; however, there were varying proning regimens and durations.
While the literature has yet to define a compliance benchmark in awake patients to achieve improved outcomes, adhering to a more structured proning protocol for a longer time period along with providing ongoing patient education may improve proning compliance and therefore outcomes. In addition, the optimal proning regimen, regarding length of time prone and number of episodes prone, is still unknown and future randomized controlled trials should be performed to determine it.
This study has several limitations. First, although our sample size of 92 in the prone group is larger than most prior studies, it remains a small, single center study. Second, this study was not designed to determine the optimal proning regimen, and future studies should be conducted to elucidate this. Third, this study was originally designed to investigate clinical outcomes, and in doing so, patients who did not prone during the intervention time period were excluded. This introduces a selection bias and artificially elevates the compliance calculation. Therefore, the actual compliance is likely to be lower. Additionally, in the setting of an overwhelmed COVID-19 hospital ward in the height of the pandemic, documentation in the electronic medical record was likely limited and therefore missing data points and proning episodes was probable.
Conclusion
In conclusion, prone positioning in non-intubated COVID-19 patients on a general ward is feasible; however, compliance with true prone positioning and length of proning was poor. Our results suggest that compliance is a limiting factor to improving outcomes.
Footnotes
Disclosures: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. There are no disclosures or sources of funding.
- Received February 2, 2023.
- Revision received August 14, 2023.
- Accepted October 3, 2023.
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