Management of severe respiratory failure following influenza A H1N1 pneumonia

Abstract

The use of non-invasive ventilation (NIV) in severe hypoxemic respiratory failure (PaO 2 /FIO 2 ≤250) due to H1H1 virus pneumonia is controversial. In this prospective study, we aimed to assess the efficacy of NIV in avoiding endotracheal intubation and to identify predictors of success or failure. Nineteen patients with H1N1 viral pneumonia had severe respiratory failure (PaO 2 /FIO 2 ratio ≤250). Five patients with PaO 2 /FIO 2 lower than 150 and simplified acute physiology score (SAPS II) lower than 34 underwent NIV and were admitted to the Intensive Care Unit and received NIV as first-line therapy. NIV failed in 2 of the 14 patients but had a good outcome in 12. None of the patients treated with NIV died. The duration of NIV was 5.0±1.9 days and the hospital stay was 11.3±1.2 days. The average PaO 2 /FIO 2 ratio after 1 h of NIV was 239.1+38.7. No patient had multi-organ failure. PaO 2 /FIO 2 ratio after 1 h and SAPS II at admission were independent variables correlated with the success of NIV. In our study, NIV was successful in 12 of the 14 patients (85.7%) and this is one of the highest success rates in the literature. In our opinion, the reason for these results is the strict selection of patients with severe respiratory failure (PaO 2 /FIO 2 ratio ≥150) and the strict following of predictors of success for NIV such as SAPS II of 34 or lower and PaO 2 /FIO 2 ratio of 175 or lower after 1 h of NIV. Clinicians should be aware of pulmonary complications of influenza A H1N1 and strictly select the patients to undergo NIV. NIV could have an effective and safe role in reducing the high demand for critical care beds, particularly during the pandemic.

Noninvasive respiratory support in acute hypoxemic respiratory failure associated with COVID-19 and other viral infections

“…Interfaces used were specified in only 6 out of 21 studies (28%) 27-30, 35, 39 . Oro-nasal and total face masks 28, 29, 35, 39 were the most widely used interfaces for NIV/CPAP, with the use of the helmet reported only in the Spanish experience 27 , as shown in Table 1.…”

“…Second, timing and patient selection should be clearly defined. Most of the examined studies showing benefits of NIV suggested the early enrollment (P/F<300) 28 , or to start in subjects with less severe disease 25, 29, 30, 55 , even if these patients might have got better anyway. Few studies described criteria of initiation of NRS 29, 48, 50 ; most of the trials are retrospective and sometimes the decision to start was made by the physician on duty on clinical rounds.…”

“…Most of the examined studies showing benefits of NIV suggested the early enrollment (P/F<300) 28 , or to start in subjects with less severe disease 25, 29, 30, 55 , even if these patients might have got better anyway. Few studies described criteria of initiation of NRS 29, 48, 50 ; most of the trials are retrospective and sometimes the decision to start was made by the physician on duty on clinical rounds. Based on these findings, the interval between the onset of AHRF and the initiation of a gentle NRS trial is crucial to “buy time” for medical therapy to take effect and possibly reverse the underlying cause of respiratory failure.…”

“…Moreover, NIV delivery is an added challenge for the clinician: it is highly time-consuming and needs specific skills to be performed. Probably, to get the most from this noninvasive strategies, specialized care provided by a respiratory and highly expert critical care team 28 and an appropriate location such as High Dependency Units (HDUs) 28, 29 might be the best compromise to accommodate the major number of patients, deliver cost-effective NRS trials and relieve the burden of ICU beds availability, as it has been described in Italy during the COVID outbreak 19 .…”

“…Few studies 25,[28][29][30] reported the specific criteria before NRS initiation. Almost all the studies were conducted in ICU settings [23][24][25][26][27][30][31][32][33][34][35][36][37][38][39][40][41][42] except two that were performed in both ICUs and High Dependency Units (HDUs) 28,29 .…”