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A 43-year-old morbidly obese woman presented for gastroplasty. Her past medical history included treated hypothyroidism and past surgical history was unremarkable. She reported functional Class II to III dyspnea on exertion. Her medications consisted of L-thyroxine, amitriptyline, codeine, and furosemide. Laboratory investigations and ECG were normal. She weighed 340 lb (150 kg) and was 5 ft 6 in (168 cm) tall. Preoperative airway examination revealed normal mouth opening with full teeth, a thyromental span of 7 cm, and good jaw protrusion. She demonstrated a modified Mallampati Score III and had slightly restricted head extension. The rest of her physical examination was unremarkable.
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Following appropriate positioning and denitrogenation, a rapid-sequence induction (RSI) was performed using midazolam, fentanyl, propofol, and succinylcholine. Direct laryngoscopy using a Macintosh #3 blade revealed a Cormack/Lehane (C/L)1 Grade 2 view. Although some difficulty with tube passage was encountered, successful tracheal intubation using a styletted 7-mm internal diameter (ID) endotracheal tube (ETT) occurred on the second attempt. General anesthesia was maintained with sevoflurane, further doses of fentanyl, and rocuronium for muscle relaxation. Two liters of Lactated Ringer were given during the 2-hour procedure. On emergence, residual neuromuscular blockade was fully reversed, and she demonstrated a regular pattern of spontaneous respiration, with good tidal volumes.
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At this time, the patient vigorously bit down on the ETT. For a period of approximately 90 seconds, no gas exchange occurred, even with attempted assisted manual ventilation via the anesthetic circuit. Although respiratory efforts continued, no CO2 trace was apparent during the episode. Oxygen saturation fell to 78% before her jaw relaxed somewhat, allowing assisted, then spontaneous ventilation to resume. She was subsequently placed in the lateral position until her eyes opened and she was able to obey commands. At this point, she was extubated. Shortly after extubation, she began to cough up frothy, pink fluid without either retching or vomiting. Her oxygen saturation, which had been 97% on a simple oxygen face mask immediately post-extubation, dropped to 85%.
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58.2.1 What Is Post-Obstructive Pulmonary Edema?
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Post-obstructive pulmonary edema (POPE) is characterized by the sudden onset of pulmonary edema of varying severity following vigorous inspiratory efforts against an obstructed upper airway. It most often occurs in a patient with no intrinsic cardiac, neurologic, or pulmonary disease. POPE usually presents with dyspnea, tachypnea, hypoxemia, and a cough productive of pink, frothy sputum. After confirming that the obstruction has been relieved, treatment of POPE is usually symptomatic, and varies from simple application of supplemental oxygen, to intubation with mechanical ventilation and application of positive end-expiratory pressure (PEEP). The condition usually resolves within 24 to 48 hours and most patients suffer no long-term sequelae.
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Pulmonary edema following acute upper airway obstruction was first described in children in 1973.2 A few years later, Oswalt described a number of cases of respiratory distress and pulmonary congestion following episodes of severe acute upper airway obstruction in otherwise healthy ...