A 68-year-old man was admitted to the intensive care unit 5 days ago due to septic shock and respiratory failure from pneumonia. The patient has been treated with intravenous fluids, vasopressors, broad-spectrum antibiotics, and intubation with mechanical ventilation. Blood cultures have resulted with Streptococcus pneumoniae, and the antibiotics have been tailored based on the sensitivity. Vasopressors have been weaned off and the sedation has been held. Current ventilator settings are assist-control mode with tidal volume 480 mL (8 mL/kg body weight), fraction of inspired oxygen (FiO₂) 35%, and positive end-expiratory pressure (PEEP) 5 cm H₂O. Temperature is 37.2 C (99 F), blood pressure is 118/74 mm Hg, pulse is 86/min, and respirations are 18/min. On physical examination, the patient is awake with the endotracheal tube in adequate position. He answers questions with head nods and follows simple commands such as to lift his head off the pillow. Lung auscultation reveals right-sided crackles. Heart sounds are normal. The extremities are warm without edema and the distal pulses are normal. Leukocyte count is 10,800/mm³, and arterial blood gas testing reveals pH 7.45, pCO₂35 mm Hg, and PaO₂ 82 mm Hg. Which of the following is the most appropriate next step in management of this patient?

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Explanation: Mechanical ventilation with intubation is associated with a number of serious complications (eg, pneumonia, pulmonary barotrauma); therefore, its duration should be minimized as much as possible. The initial criteria for extubation readiness include: pH >7.25 Adequate oxygenation (eg, PaO₂ ≥60 mm Hg) on minimal support (ie, fraction of inspired oxygen [FiO₂] ≤40% and positive end-expiratory pressure [PEEP] ≤5 cm H₂O) Intact inspiratory effort and sufficient mental alertness to protect the airway Because there is short-term risk of recurrent respiratory failure requiring reintubation, most patients who meet the above criteria should undergo a spontaneous breathing trial (SBT) to help confirm readiness for extubation. During an SBT, patients remain intubated but ventilatory support is turned off (Choice C), allowing patients to breathe on their own for a short period of time (eg, 1-2 hours). This patient is ready for an SBT as he is alert (ie, following commands) and has a normal arterial blood gas (ABG) on minimal ventilator settings. Patients who maintain normal ABG parameters throughout an SBT are good candidates for successful extubation. Candidacy for successful extubation may be further assessed during an SBT using the rapid shallow breathing index (RSBI), which is calculated by dividing respiratory rate (per minute) by tidal volume (liters). Patients with a high RSBI (eg, >105) are breathing fast and shallow and are unlikely to do well without continued ventilatory support. normal (Choices A) Tidal volume can be decreased to either reduce ventilation (and correct a respiratory alkalosis) or to lower the risk of barotrauma. However, a decrease is not necessary in this patient as his ABG is within normal limits and the tidal volume is currently at the recommended level to minimize barotrauma (eg, 6-8 mL/kg). (Choice B) Extubation without an SBT can be appropriate for patients who were intubated for an elective surgical procedure; however, patients who were intubated for a medical reason (eg, respiratory failure) are at relatively high risk for requiring reintubation and should not be extubated without a successful SBT. (Choice E) Because an endotracheal tube can cause damage to the larynx and upper trachea over time (eg, tracheal stenosis), tracheostomy is indicated when prolonged intubation (eg, >7-10 days) is required. tracheostomy Educational objective: The initial criteria for extubation readiness include pH >7.25, adequate oxygenation on minimal ventilator settings, and sufficient mental alertness to protect the airway. Patients who meet these criteria should undergo a spontaneous breathing trial to help confirm candidacy for successful extubation. References: Work of breathing during successful spontaneous breathing trial. (http://www.ncbi.nlm.nih.gov/pubmed/19327319)

A 68-Year-Old Man Was Admitted to the Intensive Care Unit