The most common drugs that may lead to apnea in the operating room include muscle relaxants or highly potent opiates (such as sufentanil, which is ten times as potent as fentanyl). Alternatively, the patient may have a previously unrecognized metabolic disorder such as a neuromuscular disease (i.e., myasthenia gravis) or a structural abnormality (i.e., stroke or embolism) that needs to be evaluated. Treatment of medication-induced respiratory depression adverse event varies by cause (see Table 28.3). When respiration is depressed by opiates, as evidenced by miotic, unresponsive pupils, naloxone (Narcan) in 0.04 mg increments may be titrated to reverse the condition. In the case of persistent peripheral muscle blockade, typically due to residual muscle relaxants, reversal with neostigmine is initiated. Other interventions include discontinuation of anesthetics, determination of arterial blood gases, and appropriate adjustment of ventilation.

Because the apneic episode lasted longer than 30 min, the anesthesia team began to question their initial assumption that the apnea was due to 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 (a long-acting paralytic agent) in adjacent medication slots. The vials were of the same size and shape, with similar red plastic caps (see Fig. 28.1). The team realized that the patient had received vecuronium 10 mg, not cefazolin 1 g, and that the observed apnea was therefore due to unrecognized muscle relaxation.

There are few accurate measures of the morbidity and mortality associated with anesthesia [15]. It has been estimated that between 2000 and 10,000 patients die each year from causes at least partially related to anesthesia, but those estimates are based on circumstantial data and include all patients regardless of age or physical status [16]. A recent study in the United Kingdom found that only one patient in 185,000 died solely as result of anesthesia, although 1 in 1351 deaths was in part related to anesthesia [17]. An estimated 44,000–98,000 Americans die in hospitals each year as a result of preventable medical errors [18]. Bates and colleagues have shown that medication errors were the number one cause of adverse and preventable patient events that 6.5 % of admitted patients suffered an adverse drug event, and they lead to more than 7000 deaths annually [19]. Of these events, 28 % were due to errors, and an additional 5.5 % involved near misses caught due to interception of the error. In the Harvard Medical Practice Study, adverse drug events accounted for 19.4 % of all disabling adverse events, 45 % of those events were caused by errors [20]. In a large insurer’s study, injuries due to drugs were the most frequent cause of procedure-related malpractice claims [21]. The prevalence of medication errors in the operating room is not accurately known. A recent study demonstrated that about half of all surgeries involve some kind of medication error or unintended drug side effects, a rate calculated by researchers who observed 277 procedures and found that 1 in 20 perioperative medication administrations included a drug error and/or an adverse drug event [22]. Perioperative areas are among the only remaining patient care areas that have not had rigorous assessments of medical errors to guide proposed solutions. Reductions in MEs in other patient care areas, including inpatient units and outpatient clinics, have occurred because error rates were measured, errors were categorized to determine their root causes and potential for harm, solutions were designed and implemented, and error rates were then systematically measured again to show a reduction. This process has occurred with solutions such as computerized physician order entry systems, bar-code scanning systems for medication administration in hospital pharmacies, and outpatient electronic prescribing systems [4, 23–25].

Wrong medication administration in the operating room is due to failure to label syringes, incorrect matching of labels on syringes and drug ampules, failure to read the label on the vial/ampule, misuse of decimal points and zeroes, and inappropriate abbreviations. What happened to this patient illustrates an example of faulty drug identity checking, where two drugs were packaged in similar vials, so that one was easily mistaken for the other. Poor system design also makes errors difficult to intercept before injury occurs. Leape and colleagues discovered that failures at the system level were the real culprits in more than three-fourths of adverse drug events [26]. Reason and colleagues suggested that some complex healthcare systems are more vulnerable and therefore more likely to experience adverse events [27].

Documenting errors at the administration stage is difficult, because it requires direct observations and reliable, robust near-miss and adverse-event reporting systems . Currie and colleagues found 144 incidents related to drugs, of which 58 were related to syringe or drug swaps [28], among the first 2000 incidents of the Australian Incident Monitoring System . Of those 58 events, 71 % involved muscle relaxants. Implementing a red syringe color change for all succinylcholine drug administration in Australia has helped to reduce drug and syringe swap by 70 % [29]. A large, retrospective study of anesthesiologists’ self-reported incidents found that of a total of 1089 incidents, 71 were related to either syringe or drug ampule swap (7 %) [30]. Leape and colleagues found that 40 of 334 errors (12 %) at the stage of drug ordering and delivery were due to imperfect dose and identify checking [26]. Studies in intensive care units have produced similar results [31].

Administrative medication errors in the operating room and intensive care unit are believed to be more common in unfamiliar settings, when drug packaging or ampules have changed, when similarly appearing ampules are stored close together in the medication carts , when syringes are prepared by other personnel, when handwritten labels are used, and when lighting conditions are poor [32]. There is an exponential relationship between the number of drugs administered to a patient and the prevalence of adverse drug events [33].

Although there is no excuse for failing to read medication and syringe labels, the occasional failure to do so represents an expected “slip,” more likely to occur with fatigue, distraction, or other causes of momentary lapses in concentration and failures in automatic behaviors [34, 35]. Not until recently did the pharmaceutical industry realize the importance of packaging medications to easily facilitate rapid identification of and discrimination between potent drugs used in operating rooms. For years muscle relaxants such as pancuronium vials were very similar to those of heparin. Some manufacturers continue to package ephedrine in ampules similar to those of oxytocin and epinephrine. This problem also occurs with different doses of the same drug—the vials for at least three concentrations of atropine sulfate from one manufacturer are similar. This results in inadvertent over- and underdosing.

Any medication drawn into a syringe for later use should be labeled immediately. Unlabeled and incorrectly labeled syringes invite errors in drug administration and dosing and should be discarded. Routine use of approved, commercial color-coded labels may reduce these errors. The labels should conform to the standards of the American Society for Testing and Materials (ASTM) [36].

A cluttered and disorganized workspace also predisposes to medication errors and searches that can delay administration of emergency medications. All anesthesia and resuscitation medication carts should be standardized (see Fig. 28.2), by applying a systematic method for stocking new and discarding outdated medications.

To understand the causes of errors, we must examine what happened, what was the root cause, and what were the underlying system failures. In a system analysis, people are viewed as an important safety resource, not only a source of errors. Designing robust transparent systems, with built in feedback control strategies, is important given human flexibility and fallibility. This was a case of unintentional administration of a paralytic agent in place of an antibiotic due to similar packaging. System checks that could be implemented here to avoid inadvertent drug swaps include color-coded labeling and reorganization of the anesthesia cart (see Table 28.4).

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