Prone position ventilation in non-intubated,spontaneously ventilating patients: New guidance from the Intensive Care Society (UK) and existing evidence

Introduction

Prone position invasive positive-pressure ventilation is a well-established treatment for acute respiratory distress syndrome (ARDS). Many centres worldwide are considering the use of prone positioning in conscious patients with COVID-19 pneumonia, and the Intensive Care Society (UK) recently published guidance on the subject. Our aim was to clarify what evidence exists on the use of prone positioning in conscious, non-intubated patients.

Literature review

We searched the PubMed database for studies on the use of prone positioning, restricted to those investigating its effects in non-intubated patients. Our findings are summarised in Table 1.

Table 1.

Studies on the use of prone positioning in non-intubated patients.

References	Type	Number of patients	Comment
Valter et al. 1	Case series	4	Acute respiratory failure secondary to pneumonia in a mixed population
Feltracco et al. 2	Case series	2	NIV in prone and Trendelenburg position after bilateral lung transplant
Feltracco et al. 3	Case series	3	NIV with high-frequency percussive ventilation in prone position post-lung transplant
Scaravilli et al. 4	Retrospective observational study	15	Compared pre-/intra-/post-proning parameters. Improved oxygenation, no detrimental effects on ventilation or haemodynamics
Ding et al. 5	Prospective cohort study	20	20 ARDS patients, pre-COVID 11 non-intubated: 8 moderate + 3 severe ARDS 9 intubated: 2 moderate + 7 severe ARDS
Sun et al. 6	Letter	n/a	COVID cohort. Proning, NIV and restrictive fluids in combination. Lower intubation rate than previous study of ARDS

ARDS: acute respiratory distress syndrome; NIV: non-invasive ventilation; n/a: not applicable.

Valter et al. published a case series ¹ of four patients with acute respiratory failure resulting from pneumonia: all demonstrated an improvement in hypoxaemia following conscious proning. Feltracco et al. published two case series^2,3 (n = 5) of lung transplant patients treated with NIV and proning; treatment was well tolerated and demonstrated improved respiratory function.

A retrospective study by Scaravilli et al. ⁴ assessed 15 patients receiving a total of 43 proning manoeuvres; they demonstrated improvement in oxygenation while proned with no evidence of adverse effects on ventilation or haemodynamic stability, and the procedure was generally well tolerated. However, the improvement in hypoxaemia did not last when the patients were returned to a supine position.

Ding et al.'s prospective cohort study ⁵ looked at the use of early prone positioning in 20 patients with moderate-to-severe ARDS, combined with either NIV or high-flow nasal cannulae. Eleven patients avoided intubation entirely, whilst two were unable to tolerate proning.

In March 2020, Sun et al. published a letter ⁶ describing their early experiences of the COVID-19 pandemic from Jiangsu province, China. They reported a better cure rate than national data, and partly attributed this to a combined approach of early awake proning, non-invasive ventilation and restrictive fluid resuscitation. They also noted a reduced rate of intubation when compared with a previous study of ARDS in mainland China.

Conclusion

The existing evidence on the use of prone positioning in conscious patients consistently demonstrates improvement in hypoxaemia, albeit in small case series and cohort studies which utilise different protocols. It is tolerated by the majority of patients, with a low risk profile.

In the context of the COVID-19 pandemic, conscious proning has several important additional benefits: there is no need to procure new drugs or equipment, and it doesn't place any additional stress on oxygen-delivery infrastructure. The treatment may be administered on a ward with nursing supervision, relieving already strained critical care facilities, and potentially providing another therapeutic option to those patients for whom admission to intensive care would be either not suitable or impossible due to resource-restricted settings.

Given the limited data on this subject, and positive early anecdotal accounts, further investigation is warranted; the authors eagerly anticipate the results of the current ProCov clinical trial (ID: NCT04344106). As we find ourselves in a situation with a novel, rapidly spreading disease which does not appear to conform to many of our existing paradigms of respiratory failure, this unorthodox but simple treatment may be of benefit.