Background
Intraoperative hypotension and hypocarbia are harbingers of severe hemodynamic compromise. Swift action to treat the underlying cause can prevent adverse perioperative outcomes. True anaphylaxis is rare in general anesthesia, the diagnosis of which is difficult and invites collaboration between allergists and anesthesiologists. The objective of this report is to highlight the management of intraoperative hemodynamic instability from presumed anaphylaxis, despite equivocal etiology.
Case Description
A 41-year-old obese woman with history of DMII and psoriasis was seen for laparoscopic cholecystectomy. She had a remote history of hives with penicillin and shellfish. Past surgeries included appendectomy and a neck mass excision without incident. Following pre-oxygenation, she was induced with fentanyl, propofol, and rocuronium, and her airway was secured with an endotracheal tube (ETT). Surgery began 10 minutes after cefazolin was administered for antibiotic prophylaxis and after skin preparation with betadine. She was hemodynamically stable. Then, upon insertion of a trochar into the right upper quadrant for laparoscopic access, end-tidal CO2 acutely dropped from 41 to 25 mmHg, with concurrent drop in mean arterial pressure from 90 to 30 mmHg and SpO2 from 99% to 90%. Surgeons were immediately notified. Breath sounds were diminished bilaterally, with right side slightly more diminished. A 14-gauge needle was inserted into the second intercostal space as thoracostomy for possible pneumothorax without audible return of air. Concurrently, a total of epinephrine 40 mcg, dexamethasone 20 mg, albuterol 900 mcg, and diphenhydramine 50 mg were given with improvement in hemodynamics. Once the patient was stabilized, fiberoptic scope verified placement of ETT above the carina. Breath sounds were equal and chest x-ray was negative for pneumothorax. The procedure was aborted. Post-operative serum tryptase level, drawn within one hour of the event, was normal at 3 ng/mL, and follow-up allergy skin testing for rocuronium was negative.
Discussion
Anesthesiologists frequently encounter acute derangements in vital signs without obvious precipitating cause. In this case, a wide differential consisting of tension pneumothorax from trochar placement, endobronchial intubation, and anaphylaxis was considered and addressed. Large body habitus, along with ambient operating room noise, limited the reliable evaluation of breath sounds. A needle thoracostomy was performed due to its high diagnostic and therapeutic yield if indeed a pneumothorax were present. No rush of air was heard, either indicating absence of pneumothorax or inadequate access to the pleural cavity due to a thick chest wall. Fiberoptic scope ruled out endobronchial intubation. Serum tryptase level was normal, which can be seen in 36% of anaphylactic patients; sensitivity of this marker for anaphylaxis would be increased if serial measurements had been taken. Although rocuronium skin test was negative, the allergy clinic is unable to perform an intravenous challenge, which is the standard route of administration. Finally, given previously reported history of hives to penicillin and shellfish, it was recommended that cefazolin and betadine be avoided in the future.
The diagnosis of anaphylaxis is challenging; often a specific trigger cannot be identified. As described, prompt management of presumed anaphylaxis is essential and can lead to avoidance of significant morbidity
