This paper reports the authors' preliminary experience with three patients affected by severe acute hypoxemic respiratory failure due to bilateral pneumonia placed in a prone position in Emergency Medicine Ward during application of high flow oxygen nasal cannula.
IntroductionIt is well known that, compared with the supine position, placing patients in a prone position determines a beneficial effect of tidal volume distribution, in part by reversing the vertical pleural pressure gradient, which becomes more negative in the dorsal pulmonary regions, thus improving the ventilation/perfusion ratio. Prone position also improves resting lung volumes in dorso-caudal regions by reducing the superimposed pressures of both heart and abdominal organs.1-3 The final result of prone positioning in most subjects with acute hypoxemic respiratory failure due to severe pulmonary consolidation is to exhibit mild to dramatic improvements in oxygenation.
Case ReportIn the last three months, three patients were admitted to our Emergency Medicine Ward because they were affected by acute respiratory failure due to pneumonia. Their chest computed tomography (CT) reveals pulmonary infiltrates and ground glass opacities. All patients complained dyspnea, cough and presented arterial blood gases with a PaO 2 /FiO 2 ratio <150. Figures 1 and 2 show the chest X-ray and chest CT scan of one of the three patients.We obtained also an early Intensivist evaluation, which excluded endo-tracheal intubation and admission to Intensive Care Unit.Antibiotics were immediately administrated, saline infusion as needed and patients were submitted to a trial of non-invasive mechanical ventilation. We started with Bi-level Positive Airway Pressure (BiPAP) with a positive end-expiratory pressure (PEEP) of 8 to 12 cm H 2 O, pressure support at 8 to 10 cm H 2 O and FiO 2 at 50%. Every four hours BiPAP was transient interrupted and alternated with two hours of high flow oxygen nasal cannula (HFNC) applied at FiO 2 at 50% with a 60 L/min flow.As reported in Table 1, the most important end points (PaO 2 /FiO 2 ratio and respiratory frequency) did not show any significant improvement in the first 48 hours. For this reason, we placed our patients in a prone position for six hours/day with immediate beneficial effects, both on symptoms and gas exchange. The combination of prone positioning and BiPAP/HFNC improved significantly PaO 2 /FiO 2 ratio with a reduced respiratory frequency within three-four days. Arterial blood gases data (mean values and range) of patients are reported in Table 1.We decided to apply HFNC during prone positioning because it was more confortable than BiPAP for a not-intubated patient.HFNC is a relatively recent method to deliver oxygen in hypoxemic patients. The main advantages of HFNC versus conventional oxygen therapy are: maintenance of warm and humidified gas flow through airways, a good carbon dioxide washout and generation of a slight PEEP. [4][5][6][7] After ten days from admission in our Emergency Medicine Ward, the patient wa...