Prevalence and outcome of heparin-induced thrombocytopenia diagnosed under veno-arterial extracorporeal membrane oxygenation: a retrospective nationwide study.

PURPOSE: Thrombocytopenia is a frequent and serious adverse event in patients treated with veno-arterial extracorporeal membrane oxygenation (VA-ECMO) for refractory cardiogenic shock. Similarly to postcardiac surgery patients, heparin-induced thrombocytopenia (HIT) could represent the causative underlying mechanism. However, the epidemiology as well as related mortality regarding HIT and VA-ECMO remains largely unknown. We aimed to define the prevalence and associated 90-day mortality of HIT diagnosed under VA-ECMO. METHODS: This retrospective study included patients under VA-ECMO from 20 French centers between 2012 and 2016. Selected patients were hospitalized for more than 3 days with high clinical suspicion of HIT and positive anti-PF4/heparin antibodies. Patients were classified according to results of functional tests as having either Confirmed or Excluded HIT. RESULTS: A total of 5797 patients under VA-ECMO were screened; 39/5797 met the inclusion criteria, with HIT confirmed in 21/5797 patients (0.36% [95% CI] [0.21-0.52]). Fourteen of 39 patients (35.9% [20.8-50.9]) with suspected HIT were ultimately excluded because of negative functional assays. Drug-induced thrombocytopenia tended to be more frequent in Excluded HIT at the time of HIT suspicion (p = 0.073). The platelet course was similar between Confirmed and Excluded HIT (p = 0.65). Mortality rate was 33.3% [13.2-53.5] in Confirmed and 50% [23.8-76.2] in Excluded HIT (p = 0.48). CONCLUSIONS: Prevalence of HIT among patients under VA-ECMO is extremely low at 0.36% with an associated mortality rate of 33.3%, which appears to be in the same range as that observed in patients treated with VA-ECMO without HIT. In addition, HIT was ultimately ruled out in one-third of patients with clinical suspicion of HIT and positive anti-PF4/heparin antibodies.

High-Flow Nasal Oxygen vs Noninvasive Positive Airway Pressure in Hypoxemic Patients After Cardiothoracic Surgery: A Randomized Clinical Trial.

IMPORTANCE: Noninvasive ventilation delivered as bilevel positive airway pressure (BiPAP) is often used to avoid reintubation and improve outcomes of patients with hypoxemia after cardiothoracic surgery. High-flow nasal oxygen therapy is increasingly used to improve oxygenation because of its ease of implementation, tolerance, and clinical effectiveness. OBJECTIVE: To determine whether high-flow nasal oxygen therapy was not inferior to BiPAP for preventing or resolving acute respiratory failure after cardiothoracic surgery. DESIGN AND SETTING: Multicenter, randomized, noninferiority trial (BiPOP Study) conducted between June 15, 2011, and January 15, 2014, at 6 French intensive care units. PARTICIPANTS: A total of 830 patients who had undergone cardiothoracic surgery, of which coronary artery bypass, valvular repair, and pulmonary thromboendarterectomy were the most common, were included when they developed acute respiratory failure (failure of a spontaneous breathing trial or successful breathing trial but failed extubation) or were deemed at risk for respiratory failure after extubation due to preexisting risk factors. INTERVENTIONS: Patients were randomly assigned to receive high-flow nasal oxygen therapy delivered continuously through a nasal cannula (flow, 50 L/min; fraction of inspired oxygen [FiO2], 50%) (n = 414) or BiPAP delivered with a full-face mask for at least 4 hours per day (pressure support level, 8 cm H2O; positive end-expiratory pressure, 4 cm H2O; FiO2, 50%) (n = 416). MAIN OUTCOMES AND MEASURES: The primary outcome was treatment failure, defined as reintubation, switch to the other study treatment, or premature treatment discontinuation (patient request or adverse effects, including gastric distention). Noninferiority of high-flow nasal oxygen therapy would be demonstrated if the lower boundary of the 95% CI were less than 9%. Secondary outcomes included mortality during intensive care unit stay, changes in respiratory variables, and respiratory complications. RESULTS: High-flow nasal oxygen therapy was not inferior to BiPAP: the treatment failed in 87 of 414 patients with high-flow nasal oxygen therapy (21.0%) and 91 of 416 patients with BiPAP (21.9%) (absolute difference, 0.9%; 95% CI, -4.9% to 6.6%; P = .003). No significant differences were found for intensive care unit mortality (23 patients with BiPAP [5.5%] and 28 with high-flow nasal oxygen therapy [6.8%]; P = .66) (absolute difference, 1.2% [95% CI, -2.3% to 4.8%]. Skin breakdown was significantly more common with BiPAP after 24 hours (10% vs 3%; 95% CI, 7.3%-13.4% vs 1.8%-5.6%; P < .001). CONCLUSIONS AND RELEVANCE: Among cardiothoracic surgery patients with or at risk for respiratory failure, the use of high-flow nasal oxygen therapy compared with intermittent BiPAP did not result in a worse rate of treatment failure. The findings support the use of high-flow nasal oxygen therapy in similar patients. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01458444.