In Reply: In response to Drs Spronk and Schultz, because our study was observational there was no specific effort to implement a low tidal volume strategy. Many patients exhibited unusually high tidal volumes, particularly in the early phase of their illness. Relatively few patients were ventilated with volume-controlled modes. For that reason, tidal volumes of approximately 6 mL/kg could not be guaranteed, particularly as lung compliance seemed relatively well preserved (despite severe hypoxemia) early in the course of the illness. Although a low tidal volume strategy was often attempted initially, the requirement for exceptional levels of sedative drugs to blunt a very high apparent respiratory drive made provision of adequate sedation extremely difficult.1 Spontaneous ventilation (pressure support) or other pressure-limited ventilation without regard to restriction of tidal volume was permitted in many patients because oxygenation appeared equivalent or better with this approach. The treating physician was often left balancing the potential benefits of low tidal volume ventilation with the need to heavily sedate and potentially paralyze those patients who were doing well with spontaneous modes of ventilation, albeit at higher tidal volumes.
Clare Ramsey, Robert A. Fowler, Anand Kumar. Mechanical Ventilation in Critically Ill Patients With 2009 Influenza A(H1N1)—Reply. JAMA. 2010;303(10):939–941. doi:10.1001/jama.2010.198