Unexplained apnea during surgery

AORN Journal, June, 2008

The Case

A 15-year-old boy underwent elective right knee arthroscopy and debridement under general anesthesia with a laryngeal mask airway. The patient was healthy with no medication allergies. The induction of anesthesia was uneventful. At the surgeon's request, the anesthesiologist administered cefazolin immediately after induction.

Just before the surgical incision was made, the anesthesiologist administered 50 mcg of fentanyl. About two minutes later, the patient's spontaneous respirations slowed, and he became apneic. The surgeon and anesthesiologist assumed the patient's apnea was caused by opiate sensitivity and assisted the patient's ventilation by hand for 30 minutes; however, spontaneous respirations did not return.

Because the apneic episode lasted longer than 30 minutes, the anesthesia team members began to question their initial assumption that the apnea was caused by opiate sensitivity. They had obtained the cefazolin from the medication drawer of the anesthesia cart. The anesthesia team examined the drawer and found vials of cefazolin and vecuronium (ie, a long-acting paralytic agent) in adjacent medication slots. The vials were the same size and shape with similar red plastic caps.

The team realized that the patient had received vecuronium 10 mg, not cefazolin I g, and that the observed apnea was therefore the result of unrecognized muscle relaxation. Hand ventilation was continued to achieve normocapnia until the muscle relaxant had dissipated and neostigmine could be administered. After reversal of muscle relaxation, the apnea resolved, anesthesia was discontinued, and the patient was transported safely to the postanesthesia care unit, where he recovered fully and was discharged.

Discussion

Apnea during anesthesia has several etiologies, including anesthetic agents themselves; opiates, barbiturates, and benzodiazepines; and hypocarbia-induced respiratory depression. Prolonged apnea occurs more often in hyperventilated patients; neonates; elderly patients; patients with compromised renal, pulmonary, or hepatic function; hypothermic and acidotic patients; patients receiving neuromuscular blockade, aminoglycosides, or intravenous magnesium; and patients with neurological impairment or injury.

When ruling out other factors, clinicians should always consider the possibility of a wrong medication administration. Causes of medication errors in the OR include failure to label syringes, incorrect matching of labels on syringes and ampules, failure to read the label on the vial or ampule, misuse of decimal points and zeros, and use of inappropriate abbreviations. This case illustrates an example of faulty medication identity checking, where two medications were packaged in similar vials and stored next to each other so that one was easily mistaken for the other. Poor system design makes errors difficult to intercept before injury occurs.

Whenever medications are administered, robust identification systems must be present. Any medication drawn into a syringe for later use should be labeled immediately. Unlabeled and incorrectly labeled syringes invite errors in medication administration and dosing and should be discarded. Routine use of commercial, color-coded labels may reduce these errors. A cluttered and disorganized workspace also can lead to medication errors and searches that can delay administration of emergency medications. All anesthesia, nursing, and resuscitation medication carts should be standardized, with a systematic method for stocking new and discarding outdated medications.

Documenting errors at the administration stage requires direct observations and reliable, robust near-miss and adverse-event reporting systems. To understand the causes of errors, the root cause must be examined along with underlying system failures. In a systems analysis, people are viewed as an important safety resource, not only as a source of errors.

Retraining all health care professions in the six rights--right patient, medication, dose, route, time, and concentration--is critical to effective and safe medication administration. Recognizing environmental factors that distract clinicians is paramount. These include noise, interruptions, fatigue and lack of adequate rest, poor lighting, and poor information systems.

Perioperative Points

Ways to prevent medication administration errors include:

* participating in annual or more frequent education on safe medication administration;

* being alert to extreme or unexpected physical responses or changes in a patient that could signal a medication reaction;

* supporting collaborative efforts by all members of the surgical team to identify near-miss situations;

* labeling syringes carefully with color-coded, preprinted labels;

* using "ready-to-use" easily identified syringes to administer emergency medications;

* standardizing the location of medications on the anesthesia cart; and

* designing system checks into the medication administration process to prevent or reduce chances of inadvertent medication or vial confusion.