Proning in Non-Intubated (PINI) in Times of COVID-19: Case Series and a Review

Abstract

It has been well known for decades that prone positioning (PP) improves oxygenation. However, it has gained widespread acceptance only in the last few years since studies have shown significant survival benefit. Many centers have established prone ventilation in their treatment algorithm for mechanically ventilated patients with severe acute respiratory distress syndrome (ARDS). Physiologically, PP should also benefit awake, non-intubated patients with acute hypoxemic respiratory failure. However, proning in non-intubated (PINI) patients did not gain any momentum until a few months ago when the Coronavirus disease 2019 (COVID-19) pandemic surged. A large number of sick patients overwhelmed the health care system, and many centers faced a dearth of ventilators. In addition, outcomes of patients placed on mechanical ventilation because of COVID-19 infection have been highly variable and often dismal. Hence, increased focus has shifted to using various strategies to prevent intubation, such as PINI. There is accumulating evidence that PINI is a low-risk intervention that can be performed even outside intensive care unit with minimal assistance and may prevent intubation in certain patients with ARDS. It can also be performed safely at smaller centers and, therefore, may reduce the patient transfer to larger institutions that are overwhelmed in the current crisis. We present a case series of 2 patients with acute hypoxemic respiratory failure who experienced significant improvements in oxygenation with PP. In addition, the physiology of PP is described, and concerns such as proning in obese and patient's anxiety are addressed; an educational pamphlet that may be useful for both patients and health care providers is provided.

Keywords: awake proning; prone positioning; prone positioning in obese; proning; proning in non-intubated; shape matching.

Figure 1.

FiO₂ (y-axis) on different days (x-axis). Orange line shows patient on NC. Blue line shows patient on HFNC. L/min on NC has been converted to approximate FiO₂. HFNC indicates high-flow nasal cannula; NC, nasal cannula.

Figure 2.

FiO₂ (y-axis) on different days (x-axis). Orange line shows patient on NC. Blue line shows patient on HFNC. Blue arrow shows transition from NC to HFNC. HFNC indicates high-flow nasal cannula; NC, nasal cannula.

Figure 3.

Alveolar collapse at bases due to lower TPP. Alveolar overdistention was seen in the ventral areas due to higher TPP.

Figure 4.

Recruitment of alveoli in dorsal lung. Less overdistention in the ventral lung. Improved V/Q matching as blood flow pattern remains unaffected.

Figure 5.

Comparison of lung compression by the heart in supine and prone positions (Adapted from the efficacy of prone position in acute respiratory distress syndrome patients: a pathophysiology-based review. V Koulouras, World J Crit Care Med. 2016;5(2): Page 126).

Figure 6.

Blue arrows show the effect of shape matching. Supine position: Dorsal lung atelectasis due to combined effects of shape matching and gravity. Ventral lung-overdistention. Prone position: Ventral lung compression due to gravity is offset by expansion due to shape matching. Dorsal lung overdistention is prevented by compression due to shape matching.

Figure 7.

Proning in non-intubated (PINI): Key for successful bedside implementation.