Year : 2021 | Volume
: 5 | Issue : 3 | Page : 37--39
Prone positioning in COVID-19: Same for all?
Nithya Arigapudi1, Tarun Kumar Suvvari2, LV Simhachalam Kutikuppala2,
1 Dr. Pinnamaneni Siddhartha Institute of Medical Science and Research Foundation, Vijayawada, Andhra Pradesh, India
2 Dr. N.T.R. University of Health Sciences, Vijayawada, Andhra Pradesh, India
Tarun Kumar Suvvari
Dr. N.T.R. University of Health Sciences, Vijayawada, Andhra Pradesh
Proning is a medically admissible procedure in which a patient is turned onto their abdomen from their back, by precise, accurate, and secure motions. This procedure often finds itself in use as an adjunctive in the treatment of acute respiratory distress syndrome (ARDS), which is a dreadful complication of many respiratory infections, including the disease of the moment: Coronavirus disease 2019 (COVID-19). Caused by severe acute respiratory syndrome coronavirus 2, COVID-19 can lead to a plethora of complications, with ARDS, causing breathing difficulties and leading to hazardously low levels of oxygen in the blood, taking the forefront. The treatment of this condition often requires invasive ventilation; and to decrease the strain on resources providing such, several protocols have been observed to improve the breathing capability and enhance oxygen exchange, of which one is prone positioning. Here, we review various literature regarding the proning procedure in COVID-19 patients and elaborate the efficacy, merits, and demerits.
|How to cite this article:|
Arigapudi N, Suvvari TK, Simhachalam Kutikuppala L V. Prone positioning in COVID-19: Same for all?.Saudi Crit Care J 2021;5:37-39
|How to cite this URL:|
Arigapudi N, Suvvari TK, Simhachalam Kutikuppala L V. Prone positioning in COVID-19: Same for all?. Saudi Crit Care J [serial online] 2021 [cited 2021 Dec 3 ];5:37-39
Available from: https://www.sccj-sa.org/text.asp?2021/5/3/37/323609
Coronavirus disease 2019 (COVID-19), a disease that has swept across the world and challenged possibly all aspects of life, especially that of healthcare, needs no introduction; presenting through fever, dyspnea, and acute respiratory symptoms, the virus causes pneumonia which when exacerbated leads to a plethora of fatal conditions such as pulmonary edema, multiorgan failure, and acute respiratory distress syndrome (ARDS). Among these, ARDS perhaps has the highest prevalence in COVID-19 patients, the association reported to be up to 17%.
ARDS is no new syndrome, introduced first in 1968; but despite all the treatment advancements made, it continues to boast a high mortality rate ranging from around 9% to 20%. When coupled with the alarming strain on medical resources, as COVID-19 cases continue to rise in steep numbers, adjuvant therapies needing minimal requirements became a necessity, and one of those proposed was prone positioning.
Pathophysiology Behind Prone Position in Acute Respiratory Distress Syndrome
The benefits of lying in a prone position in ARDS are based on the re-expansion of the collapsed lung in dorsal regions and reduction in aeration in ventral ones, which leads to both lung recruitment and more homogenous lung aeration. The net effect is better ventilation-perfusion matching, resulting in improved gas exchange. When this modality of treatment was tried in COVID-19 patients, though there was a significant improvement in oxygenation, there was a minimal change in PaCo2, whose improvement is the factor suggestive of lung recruitment. In addition, the plateau pressure, Crs (Static respiratory system compliance), and ventilatory ratio remained stable; all further suggestive of the lack of lung recruitment induced by prone position. The only plausible explanation left for the increase in PaO2/fiO2 ratio (ratio of arterial oxygen partial pressure to fractional inspired oxygen) is a decrease in pulmonary capillary flow; if this decrease is indeed sufficient enough to improve oxygenation, it implies that a major mechanism involved in COVID-19 related ARDS is a mismatch in ventilation-perfusion ratio, and probably an intra-pulmonary shunt, both of which need to be further studied.
Prone positioning has generally been opted to trial in two groups of patients; one consisting of awake, hypoxic patients who have low SpO2 levels, and are either spontaneously breathing or receiving oxygen through noninvasive routes (more common), and another group compromising intubated patients.
Prone Position in Noninvasively Ventilated Patients
As an increasing burden fell on critical care resources, many health-care workers looked into possible methods to prevent the progression of hypoxia to an extent severe enough to warrant intubation, and one such proposed method was placing patients in a prone position. In a report on 50 patients with suspected COVID-19, from an emergency department in New York City, Caputo et al. found a significant rise in SpO2 levels a mere 5 min following pronation. In a single-center study conducted in Milan, Italy on 15 patients, who were hypoxemic despite a continuous positive airway pressure of 10 cm H2O and a 0.6 FIO2, Sartini et al. found that there was an improvement in SpO2 levels in all of them on pronation. Similarly, Zang et al. demonstrated a greater 90-day-survival rate among nonintubated severe hypoxic COVID patients who had undergone sessions of pronation when compared to the patients who had not. However, it must also be mentioned that a study by Elharrar et al., in France, found that out of 24 eligible patients with confirmed COVID-19, posterior lung opacities on computerized tomography (CT), and on 4L or less of oxygen delivered via nasal cannula, oxygenation increased in prone positioning in only 6 patients.
The results may indeed do look promising from far, but one must realize that issues of credibility extend beyond the lack of proper randomized and controlled trials; they also include variations in patient eligibility criteria, in techniques and duration of proning, and on the time of initiation with respect to the severity of ARDS in the patient, which all may play roles in the outcome of the studies.
Diving deeper, if we take a look at the study by Zang et al. described above, it was seen to be that, though not in a significant manner, a greater number of patients who had undergone early prone positioning had required subsequent invasive mechanical ventilation. Considering that we are looking toward early proning as a means to decrease the burden on resources of intubation, we must wonder whether early proning is actually preventing the necessity of intubation, or simply delaying it. This brings about the realization that the success of prone positioning cannot be measured simply on an improved SpO2 or overall survival rates.
On a positive note, a prospective study at the Royal London Hospital, evaluating parameters beyond the above mentioned, showed that patients who had been able to tolerate the prone position for >1 h had a reduced intensive care unit (ICU) admission, the patients who were admitted had a shorter duration of ICU stay, and there was also a reduced need for subsequent intubation and mechanical ventilation; but again, due to the small scale of the experimentation, the positive effects may be due to the time-dependent effect of proning, or may simply be an indicator of variable disease severity in the patients, bringing us back to the initial limitation: lack of proper trials.
Prone Position in Invasively Ventilated Patients
When it comes to the placing of an intubated patient in the prone position, we, unfortunately, have severely limited insight into the benefits we may reap. One multicentric retrospective study conducted in Italy, during the peak of their first wave, analyzed 1057 invasively ventilated patients and had concluded that there was an improvement in oxygenation on pronation, but it must be kept in mind that pronation here calls for the efforts of experienced personnel, and the maneuver frequently requires an increment in the dosage of sedatives and muscle relaxants, which may play a role in either improving the patient's condition or worsening it. In addition, there are associated risks of injury from the devices, and chances of device displacement. Another point to be noted is that there were no prespecified criteria for the implementation of proning, it was completely at the discretion of the ICU team, whose expertise, unfortunately, could not be taken to be of standardized quality, as there had been the recruitment of doctors from other specialties to compensate the increased demand at the ICU.
A retrospective study conducted by Rush University Medical Centre on 42 patients showed a positive response to proning, as determined by an increase in PaO2/FIO2 ratio ≥20%. However, it was seen that the patients who had successful treatment history had a higher BMI which may point towards the obesity survival paradox seen in pneumonia; whether or not this phenomenon is significant in COVID-19 is still to be determined.
As can be seen from the above two literatures, there are a lot of “what ifs” that need to be addressed before stating with certainty the benefit of pronation in intubated patients; and the benefits must also be weighed with the potential side effects and disadvantages, such as accidental removal of the tracheal tube, limited access to the venous route, bending or pulling of the catheters and chest tubes, formation of pressure wounds, facial edema, gastroesophageal reflux, hyper-salivation, and skin injuries.
The expected benefits of placing a hypoxic patient in a prone position clearly outweigh the expected risks, but there are yet no proper randomized controlled trials regarding this topic, making it hard to indicate the extent of benefits one will derive; keeping in mind that the benefits measured must not be limited to an improvement in oxygenation and survival, but should also be in terms of the need for subsequent ventilation, ICU admissions, and duration of ICU stay. At present, based on conducted studies, it seems that the ideal way to reap the benefits of prone positioning is when it is applied to patients in the initial hours of COVID-19 manifestation, in patients suffering from severely impaired oxygenation, and for preferably prolonged periods.
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Conflicts of interest
There are no conflicts of interest.
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