Patient safety was a prominent topic in several scientific sessions at the ASA meeting in San Diego in October. Interested readers can review abstracts 952-1009 and 1020-1027 in the Anesthesiology September, 1997, supplement “Abstracts of Scientific papers, 1997 Annual Meeting.” Findings presented in a few of these abstracts are summarized here.
Highly fatigued anesthesiology residents were tested on a patient simulator and compared to well-rested residents in a study presented by Dr. S. Howard from Stanford. The fatigued residents were sleepy but managed to preserve vigilance in the (admittedly artificial and therefore possibly more stimulating than real life) test situation. Response time to clinical developments was prolonged and performance more variable, however. It was concluded that a high degree of fatigue in an anesthesia provider increases the potential for sub-optimal care.
Dr. K. Travis from Dartmouth analyzed the ages of anesthesiologists reported to the National Practitioner Data Bank and reported that older (defined as above 54) anesthesiologists are more likely to have malpractice claims against them (“improper intubation” leading the list) and suggests that further research in this area should be undertaken.
In an abstract from a study supported by a research grant from the APSF, Dr. R. Prielipp and associates from Bowman Gray/Wake Forest did a prospective trial of the effect of arm position on ulnar nerve compression and reported that supination of the arm led to significantly less pressure on the ulnar nerve than when the arm is neutral or pronated.
Beneficial Preop PO?
A paper from Sweden by Dr. M. Lagerkranser et al. Suggested that oral intake of a carbohydrate-rich beverage a short time (two hours) prior to general anesthesia actually was beneficial because it appeared associated with a reduction in postoperative nausea and vomiting and also raised the pH of the gastric contents above 2.5 so that, in the unlikely event of aspiration of stomach content, the damage from acidity would be mitigated.
Several abstracts considered various aspects of malignant hyperthermia, particularly the new proposed tests for susceptibility. One of several possible examples was by Dr. A. Urwyler from Switzerland concerning the ryanodine induced muscle contracture test, which appeared promising but needs further study to standardize the techniques. From a mechanism standpoint, the same group from Basel presented a study demonstrating altered calcium control in muscle myotubules in MH susceptible patients, leading to a hypothesis that primary muscle cell cultures may be useful in the diagnostic process.
Airway issues and management of difficult airways, as always, were subjects of several presentations. The cuffed oropharyngeal airway was compared to the standard LMA utilized during anesthetics for MRI procedures by Dr. M. Sesay et al. From Bordeaux in France. The authors concluded that both provided equivalent “hands free” anesthesia delivery. A presentation by Dr. C. Hargberg and associates from the University of Texas/Houston, suggested from a study of 87 morbidly obese patients that routine elective awake intubation in such patients is not necessarily indicated in that morbid obesity was not a predictor of difficult intubation. Another presentation from a team led by Dr. J. Parmet from Allegheny University in Philadelphia demonstrated that the application of LMA technology converted 87% of “can’t ventilate” situations into “can ventilate” scenarios, suggesting the potential value of an LMA in an emergency and that these devices should be readily available at all anesthetizing locations.
The prevention of postoperative shivering was the subject of a study presented by Dr. G. Panagopoulos from New York Methodist Hospital. It was concluded that the intraoperative administration of IV meperidine was more effective in preventing shivering than the usual mechanical warming devices (fluid warmers as well as conductive and convective skin warming apparatus) used during general anesthesia.
Another study done in Switzerland, this one by Dr. H. Gerber and colleagues, examined whether postoperative narcotic PCA causes hypoxemia. The data revealed that on the first and second post-operative nights following hip arthroplasty, there were about as many episodes of hemoglobin desaturation but that they were significantly more severe in patients using morphine PCA. In addition to implications suggesting the need for further studies, the authors strongly recommend the prophylactic administration of oxygen to such patients.
Dr. M. Rozner and a colleague from the university South Florida in Tampa studied the development of carboxyhemoglobin in the perioperative period and found there were some nonsmoking patients who had demonstrable (but not necessarily clinically significant) increases of COHb during anesthesia. They concluded that “patients undergoing general tracheal anesthesia are indeed exposed to CO from a source that remains unknown.
A study from the Mayo Clinic presented by Dr. G. Wong examined the risk of stroke associated with anesthesia and surgery. 1455 stroke victims were matched with the same number of controls and it was seen that 9.1% of stroke patients had surgery and anesthesia in the prior year compared to 5.8% of the control population, leading to the conclusion that surgery and anesthesia constitute an independent risk factor for incident ischemic stroke.
Errors in continuous pump infusions of medication in an intensive care unit were studied by Dr. D. MacGregor and associates from Bowman Gray/Wake Forest. There were errors in 42% of the infusions delivered by these devices, making such errors four times more likely than the standard baseline rate of medication errors in that ICU. The obvious potential safety implications were cited and a variety of strategies, particularly the use of standardized checklists, for avoiding such errors were suggested.
An intriguing study from the University of Florida was reported by Dr. L. Faberowski. SSEP readings were done during repair of aortic coarctations in children and it was found that SSEP changes occurred in 44% of patients and, importantly, interventions were made in 27% of all cases because of the SSEP data, suggesting that use of this monitoring device helped produce the perfect record for this surgical series of no patient suffering a neurologic deficit from cord ischemia associated with this surgery.
The traditional problem often mentioned but little studied of the accidental insertion of nasogastric tube into the trachea instead of into the esophagus was examined by Dr. P. Schanbacher and associates from the Illinois Masonic Medical Center. Such errant placement was found to occur 1.5% of the times NG tubes were placed. A variety of strategies to prevent and detect such errors were presented.
“Turn the vent back on!”
Lastly, a Dutch group headed by Dr. C. Kalkman presented a new electronic monitoring device for use during cases involving cardiopulmonary bypass that simultaneously monitors the pump and the ventilator so that an alarm signal will prominently appear at the end of bypass if the ventilator is not reactivated at the correct time. In a prospective study including 720 bypass cases, there were 5 instances in which the alarm sounded, indicating the cessation of bypass without the resumption of ventilation. The safety implications are obvious and the authors suggested a large multicenter trial of this type of monitor.
The paper briefly reviewed here only scratch the surface of the body of patient safety related research presented at the 1997 ASA meeting and readers are urged to peruse the meeting’s abstract book for further information.