• C B DeHaven, O C Kirton, J P Morgan, A M Hart, D V Shatz, and J M Civetta.
• Division of Surgical Critical Care, Department of Surgery, University of Miami School of Medicine, Ryder Trauma Center, FL, USA.
• Crit. Care Med. 1996 Jun 1;24(6):976-80.

ObjectivesThere is increased awareness of imposed work of breathing contributing to apparent ventilatory dependency. This study evaluates the impact of tachypnea as an indicator of ventilatory failure during a room air-5 cm H2O continuous positive airway pressure, spontaneous breathing, preextubation trial when associated with increased imposed work of breathing.DesignProspective, descriptive, 1-yr data collection.SettingUniversity hospital trauma intensive care unit (ICU).PatientsMechanically ventilated trauma ICU patients surviving to discharge.InterventionPatients were weaned to minimal mechanical ventilator support and underwent a 20-min room air-continuous positive airway pressure preextubation trial (FIO2 = 0.21, continuous positive airway pressure = 5 cm H2O [0.5 kPa]). When passed (PaO2 >/= 55 torr [>/= 7.3 kPa], PaCO2 /= 7.35, respiratory rate 1.1 joule/L, imposed work of breathing was measured, and if residual "physiologic" work of breathing (patient work of breathing minus imposed work of breathing) was Measurements And Main ResultsOf 589 extubations, 105 (18%) were classified as false negatives based on a preextubation rate of > 30 breaths/min. Of these, 97 were successfully extubated despite tachypnea ranging from 32 to 56 breaths/min, when combined with either a patient work of breathing ConclusionsTachypnea as a marker of respiratory distress is sensitive, but is not sufficiently specific to be used as a criterion in preextubation trials. Reliance on tachypnea as a preextubation trial failure criterion is likely to prolong intubation and ventilatory support for a large number of patients. Patient risks, determined by the extubation failures and reintubation rate, are the same.

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