A 72-year-old man is evaluated in his hospital room for hypoxemia and shortness of breath. He says, "I just can't seem to get enough air to breathe." He also has a cough that is intermittently productive of white sputum. The patient underwent emergency open colectomy 3 days ago for cecal volvulus. His course was complicated by postoperative respiratory failure, and he remained on a mechanical ventilator for 48 hours. He was extubated 12 hours ago and has since had significant pain around the incision site, receiving opioid medications as needed. Medical history includes hypertension, ischemic stroke with resulting left-sided weakness, and coronary artery disease. The patient has smoked a pack of cigarettes a day for the last 45 years. He has no history of alcohol or drug abuse. Temperature is 37 C (98.6 F), blood pressure is 145/90 mm Hg, pulse is 90/min, and respirations are 24/min. Oxygen saturation is 87% on room air. The patient appears chronically ill and drowsy. Examination shows moist mucous membranes and normal jugular venous pressure. Respirations are shallow and limited by pain around the incision. The patient has a weak cough with no stridor. Breath sounds are diminished at the bilateral lung bases, with scattered rhonchi. Heart sounds are normal. The abdomen is mildly distended and tender near the incision site. The surgical wound appears clean and is without discharge. There is 1+ bilateral edema of the lower extremities. A complete blood count and metabolic panel are normal. Arterial blood gas analysis on room air shows a pH of 7.47, PaO₂ of 56 mm Hg, and PaCO₂ of 33 mm Hg. Chest x-ray reveals small lung volumes and bilateral linear densities of the lower lobe. In addition to the supplemental oxygen to correct the hypoxemia, which of the following is most beneficial for treating this patient's respiratory symptoms?

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Explanation: 11ec2b69_c077_0a49_8f63_b54648cc223c_MD0005_00 Postoperative atelectasis is common following thoracoabdominal surgeries; it results from decreased lung compliance (a transient effect of thoracoabdominal surgery possibly due to anesthesia) as well as postoperative pain leading to hypoventilation, reduced cough, and impaired mucus clearance. Smoking, obesity, and underlying lung or neurologic disease increase the risk of postoperative atelectasis. The manifestations are usually somewhat delayed, typically occurring 2-5 days postoperatively; when symptomatic, patients may have increased work of breathing or hypoxemia. Arterial blood gas results typically reveal an increased alveolar-arterial gradient due to intrapulmonary shunting. Chest x-ray characteristically shows linear opacifications in the bilateral lung bases, sometimes with an accompanying shift of structures toward the opacification (if the atelectasis is large). For patients with minimal respiratory secretions, the administration of continuous positive airway pressure (CPAP) is often effective. However, those with more copious secretions (such as this patient with cough productive of white sputum) are most appropriately managed with aggressive pulmonary hygiene, including chest physiotherapy and suctioning, rather than CPAP. (Choice A) Ceftriaxone with azithromycin is appropriate for community-acquired pneumonia. However, the absence of fever and consolidation on chest x-ray in this patient make pneumonia unlikely. In addition, postoperative pneumonia is often caused by relatively resistant hospital-acquired pathogens; when the diagnosis is suspected, empiric treatment should include an antipseudomonal agent (eg, piperacillin-tazobactam). (Choice C) Opioids cause central respiratory depression, which can lead to hypoventilation and can contribute to atelectasis. Although minimizing the dose of opioid medication is appropriate for preventing further atelectasis in this patient, aggressive pulmonary hygiene is the most effective therapeutic intervention. (Choice D) Diuresis with intravenous furosemide is appropriate for pulmonary edema due to volume overload. Although this patient has bilateral edema of the lower extremities, the absence of jugular venous distension and pleural effusion or bibasilar alveolar infiltrates on chest x-ray make significant pulmonary edema unlikely. (Choice E) Scheduled nebulized bronchodilators are used to treat bronchospasm, a common postoperative complication that typically occurs early in the postoperative period. The absence of wheezing on physical examination makes bronchospasm less likely in this patient. Educational objective: Postoperative atelectasis is common 2-5 days following thoracoabdominal surgery and typically presents with hypoxemia or respiratory difficulty. Patients without respiratory secretions can be managed with continuous positive airway pressure, whereas those with secretions are best managed with aggressive pulmonary hygiene, including chest physiotherapy and suctioning. References: Mechanisms of atelectasis in the perioperative period. (http://www.ncbi.nlm.nih.gov/pubmed/20608554) Postoperative pulmonary complications after noncardiothoracic surgery. (http://www.ncbi.nlm.nih.gov/pubmed/26556919)

A 72-Year-Old Man Is Evaluated in His Hospital Room for Hypoxemia