Anesthesia patient safety was the subject of 63 presentations in three sessions of the scientific program at the 1999 Annual Meeting of the American Society of Anesthesiologists in Dallas, October 9-13.
One presentation (Dr. R Katz) concerned preoperative medical consultations and another (Dr. L Tsen) evaluated the impact of preoperative cardiology consultations in a high-risk population and both papers concluded that there was little or no effect on perioperative anesthesia management from these consultations.
The safety of operating on elderly patients in office-based settings was examined in a study of the Medicare database funded by the APSF and presented by Dr. L Fleisher. Readmissions per 1000 patients following outpatient cataract surgery in three locations were 2.8 for ambulatory surgery center cases, 3.5 for hospital cases, and 4.7 for office cases. A similar pattern was observed for deaths but the events are so rare as to not allow statistical significance. For hernia surgery, there was no difference in readmission or death rates by location of case. Further research on the safety of operating on elderly patients in office-based settings was recommended.
Thermal Topics Effects of hypothermia were considered in several papers. Hypothermia (<36°C) at the time of ICU admission following CABG in 5701 patients was significantly associated with multiple adverse outcome measures, reported Dr. S Insler of the Cleveland Clinic. Hypothermic patients had greater mortality, transfusion requirements, and lengths of time of mechanical ventilation, ICU stay, and hospital stay. Aggressive prevention of heat loss following CPB was recommended. Similarly, a study reported by Dr. J Berry found that in spite of "aggressive application of perioperative warming measures," 7% of postop patients arriving in the PACU were hypothermic (<35.5°C) and fully 26% of patients taken directly to an ICU arrived hypothermic. It was concluded this problem persists and is a significantly increased risk in critically ill patients. Another concern about hypothermia was raised in a report by Dr. T Matsukawa from Japan in which temperature was measured after 0.05 mg/kg of midazolam premedication and found to be significantly lower in elderly compared to young patients. Induced impairment of thermoregulatory control was postulated and a suggestion for more temperature monitoring and thermal management in such circumstances was made.
Post cardiopulmonary bypass problems were also discussed by Dr. L Davies who presented data showing that deficits seen in elderly patients in cognitive functions resolved by 3 months after CPB except in the verbal learning test and it was suggested that this marker be used to investigate late postoperative cognitive dysfunction.
Lower extremity neuropathies associated with surgery in the lithotomy position were examined in the extensive Mayo Clinic database by Dr. M Warner. 1.7% of 1150 (1 in 58) patients developed or exacerbated neuropathies. Having an anesthetic and duration of the lithotomy position were positively correlated factors for the development of lower limb neuropathy.
Review by Dr. M Trankina of patients with pacemakers coming to the OR revealed that a significant fraction of them had poor preoperative evaluations and inadequate information about the patient’s underlying condition, pacemaker specifications, and current pacemaker function. The need for better education and consensus guidelines was suggested.
The rate of post-colectomy wound infections was shown to be reduced by half in a prospective trial presented by Dr. R Greif in which the treatment group received 80% oxygen intraoperatively and for two hours postop versus the control group’s 30%. No adverse consequences of the increased FiO2 were mentioned.
A change in the number and pattern of deaths and arrests from malignant hyperthermia was reported by Dr. H Rosenberg. There were very few deaths reported, and all occurred late in the course of surgery. Causes were DIC, hyperkalemia, and renal failure. One arrest survivor was diagnosed with a muscular dystrophy after a hyperkalemic arrest.
Herbal Danger? While up to one-third of the American public has been identified as users of herbal products, a prospective study reported by Dr. C McLeskey found 17.4% of preoperative patients admitted herbal product use, most commonly gingko biloba, garlic, ginger, ginseng, and St. John’s Wort. It was advised that these medications may not be harmless and "adverse effects and drug-herbal interactions may suggest alterations in an anesthetic plan."
A greater than expected incidence of unanticipated difficult intubation in a series of 6742 "normal" patients (all airway abnormalities excluded) in Japan was reported by Dr. K Okazaki. 4.9% of the patients were found difficult to intubate; 3.4% had been rated airway class I or II and 1.5% had class III or IV airway ratings.
Transport Travails Cardiac arrests and deaths during transport from the operating room were studied by Dr. J Rosenberg at the University of Michigan. In a database of 140,721 patients, six of the seven events were judged preventable (two with inattention to pressor infusions, three of rough patient handling, and one airway problem). Another component of the study involved prospective observation of actual transports from OR to ICU and there was a 19% incidence of "near misses," all involving hypotension. Implementation of the transport guidelines of the American College of Critical Care Medicine was recommended.
More Absorbent Reactions The interaction of sevoflurane and desiccated carbon dioxide absorbent continued to be the subject of several reports. One was from Germany by Dr. H Förster in which KOH containing absorbent caused the total destruction of sevoflurane and generation of temperatures exceeding 200°C whereas KOH-free absorbent caused only "moderate" reaction but production of the five known compounds (A-E) as well as other unknown and also potentially toxic reaction products. In contrast, in another paper, it was shown that the production of carbon monoxide from desflurane interaction with desiccated absorbent is independent of its KOH content. In yet a third paper, Dr. Förster reports experiments suggesting that lithium hydroxide supported none of the problem reactions with halogenated ethers and, therefore, is the ideal carbon dioxide absorbent.
Prone Extubation? Dr. M Olympio offered prospective observations of extubating lumbar spine patients at the end of surgery in the prone position rather than after the traditional returning of the patient to the supine position. There was less coughing and fewer hemodynamic disturbances, disconnects, and losses of monitoring with no adverse events occurring.
Review of a series of 44,917 cases considered the impact of transfer of anesthesia care responsibilities during surgery. Dr. V Joseph reported that there was a significantly increased complication rate in cases lasting more than three hours, whether or not there was a mid-case transfer of responsibility. It is noted that possibly in contrast to an idea published in 1982, transfer of care does not offer any patient safety benefit.
The papers reviewed here briefly only highlight a fraction of the presentations related to patient safety at the 1999 ASA Annual Meeting. Interested readers are referred to the September, 1999 supplemental issue of Anesthesiology for more information.