So You Think You Can Safely Extubate Your Patient

Intubation and mechanical ventilation are necessary in onethird of patients who are critically ill. While life-saving, these interventions are coupled with increased acid–base disturbances, infections and organ failure [1]. In addition, both early extubation leading to reintubation and deferred extubation correlate with higher morbidity and morality and longer stays in the intensive care unit (ICU) [2, 3]. Physicians strive to determine the most appropriate time to extubate a patient with efforts to predict this dating to the earliest research in critical care [4]; however, patients still have a significant extubation failure rate, now estimated to be 13–18% of the time [5, 6]. Extubation and discontinuation of mechanical ventilation should be considered once the cause of the respiratory failure has been remedied if the patient is oxygenating without difficulty and not hemodynamically compromised. The patient should also be evaluated for ability to tolerate a spontaneous breathing trial [7]. While these recommendations guide the physician in liberating a patient from the ventilator, they do not assess if the patient’s airway is adequate to tolerate extubation. A weak cough and copious secretions are associated with an unsatisfactory airway and extubation failure [6]. Accurately judging ability to protect the airway is paramount in patients intubated solely for neurologic reasons. This unique population of critically ill patients frequently does not have respiratory failure and otherwise meet criteria for extubation. Uncertainty of a brain-injured patient’s airway can delay extubation, perhaps unnecessarily. Coplin et al. [3] followed a prospective observational cohort of 136 brain-injured patients. Twenty-seven percent of patients experienced extubation delay after meeting criteria for extubation readiness. These patients had worse neurologic status as measured by the Glasgow Coma Scale (GCS) and increased airway care requirements. Extubation delay was not necessarily associated with improvement in neurologic status. In fact, 43% of the patients who had a delayed extubation had no change or a worsening of their neurologic condition at time of extubation. A physician may choose to keep a comatose patient intubated for airway protection and prevention of pneumonia. However, 54% of pneumonias occurred after patients met criteria for extubation delay (P = 0.05). Coplin and colleagues also underscored the costs associated with extubation delay, including increased lengths of ICU and hospital stays and increased mortality. Given physicians’ trepidation in safely extubating braininjured patients, several studies have attempted to identify predictors of extubation outcome in these patients. Weaning parameters (including respiratory rate, tidal volume, rapid shallow breathing index, minute ventilation, negative inspiratory force, and the PaO2/FiO2 ratio) are not prognostic of extubation failure in patients intubated for neurologic reasons [8]. These findings are not unsurprising given these parameters evaluate pulmonary status in patients without primary pulmonary dysfunction. Neurologic status as a predictor of extubation failure has produced contradictory results. Coplin et al. [3] demonstrated that comatose patients could be extubated successfully (80 and 91% of patients with GCS B 8 and B4, respectively). Ko L. C. Wendell (&) Department of Neurology and Neurosurgery, Rhode Island Hospital/Warren Alpert School of Medicine at Brown University, Providence, RI 02906, USA e-mail: linda_wendell@brown.edu