Insights About Prone and Lateral Positioning in Spontaneously Breathing Patients With COVID-19 Pneumonia Undergoing Noninvasive Helmet CPAP Treatment

To the Editor:

The work by Retucci et al¹ in CHEST (December 2020) about the change of position during spontaneous breathing and COVID-19 pneumonia with ratio of arterial oxygen partial pressure to fractional inspired oxygen less than 250 is very interesting. A shift in position (prone or lateral), in the first 2 hours of treatment, is the principal mechanism of action in the recruitment of lung tissue, especially during noninvasive helmet CPAP. In their study, the association between CPAP use and the radiologic pattern (particularly GGO prevalence or consolidation) is not obvious.

In fact, in the pattern ground-glass opacification/opacity, the response is very quickly correlated with $\dot{\mathrm{V}}$/$\dot{\mathrm{Q}}$ matching or edema formation. Still, this benefit should disappear immediately when the patient is repositioned in the supine position, as shown in Retucci et al’s work.¹ Rather than improvements in $\dot{\mathrm{V}}$/$\dot{\mathrm{Q}}$ matching, no variation of the lung ultrasound pattern before and after prone noninvasive ventilation has been detected in the study.² In the consolidative pattern, the response is unpredictable, especially if the thickened areas are peripheral and posterior. The pronation may interrupt the process of progressive basilar atelectasis and rapid deterioration.³ However, this could be challenging in COVID-19 patients with obesity. An approach to overcome this issue is a pregnancy massage pillow, which is essentially an inflatable pillow with a cut-out to allow for a protuberant abdomen. In the prone position, this support allows release of abdominal pressure on the chest.

Another clinical problem is the patient’s prone position compliance and interface use. The helmet is the most advantageous and safest interface to give a CPAP, but it is difficult to use in prone patients.³ The most likely complications caused by prone positioning (eg, vomiting or nausea in patients with pancreatic or abdominal problems in general) would have been clinically evident. In the last period, during low-pressure CPAP use, there is a lot of pneumomediastinum and pneumothorax incidence. It is a real problem for the change of position and prone position, especially during nondrained pneumomediastinum and the placement of any drainages in patients who would require the prone position should be carefully evaluated.