Patient safety repeated this year as a prominent theme of the scientific sessions of the Annual Meeting of the American Society of Anesthesiologists October 17-21 in New Orleans. In six sessions, there were 89 individual scientific presentations.
Two papers were presented which raised concern about the potential for epidural catheter contamination. The first was offered by Drs. P. Langevin, P. Guley, and N. Gravenstein of the University of Florida at Gainesville. Their in-vitro study indicated that bacteria are not likely to migrate more than eight inches along a catheter from the point at which it is externally contaminated and that immersion of the catheter in betadine for three minutes followed by air drying for three minutes effectively sterilized it. They conclude that if the lower connector of an epidural catheter becomes inadvertently disconnected subjecting the catheter to potential contamination, it is probably safe to reconnect it if at least eight inches of the catheter is cut away using sterile technique and the cut end is treated with betadine as above. A related paper from Dr. M. Dailey, et al. of the Medical University of South Carolina presented a compilation of reports of epidural abscesses after epidural blockade. Their data, which included all reported cases of epidural abscess in the last 15 years, revealed 13 infections, all occurring in patients who had the catheters placed for pain control outside of the OR environment. These two reports emphasize the necessity for employing aseptic technique when placing epidural catheters.
Dr. 0. Hendon, et al. of the University of California at San Diego presented data from confidential questionnaires indicating that anesthesiologists
have a higher incidence of sleep disturbances than the general population. Cumulative sleep debt and poor quality sleep have the potential to hamper performance of anesthesia personnel. In a companion paper, they reported that 75% of 85 subjects drank alcohol on a regular basis, that 10% of the subjects had at least once been hung over while administrating anesthesia, and 40% administered anesthesia within 12 hours of alcohol consumption. Sixty-three percent of the anesthesia providers admitted to having ever used marijuana. Four of 38 respondents admitted to using other controlled substances including cocaine, benzodiazepines, opiates, hallucinogens, amphetamines and N20. One subject reported that he had lost consciousness during administration of anesthesia due to an overdose of midazolam. Sixteen percent of the subjects said that they had seriously contemplated suicide yet no one admitted actually attempting it. Taken together, the studies appear to indicate a significant incidence of substance abuse and mental disturbance among anesthesia personnel. (See Letter to the Editor, pg. 51.)
Drs. M. Hartmannsgraber and N. Gravenstein of the University of Florida reported a study indicating that a commercially available air eliminator supplied with a blood warmer/rapid infuser was not effective in removing large volumes of air and did not eliminate the need for rigorous air elimination from the system prior to clinical use.
Dr. R. Keenan and associates from the Medical College of Virginia reported on their study of bradycardia during anesthesia in infants. Their enquiry focused on the incidence and influencing factors on this relatively common and serious problem. They found that the likelihood of bradycardia (defined as baseline) was increased in sicker infants undergoing emergency procedures of longer duration. Independent of these variables, bradycardia was 2.2 times more likely when infants were attended by non-pediatric anesthetists than by their pediatric counterparts.
Two papers addressed the use of nitrous oxide for patients undergoing bone marrow harvest. Dr. D. Fausel and associates from the Cleveland Clinic Foundation examined the influence of nitrous oxide (during anesthesia for the donor) on time to bone marrow engraftment in recipients. They found that exposure to this agent had no significant influence on this time. Dr. G. Lederhaas and coworkers at Stanford University examined bone marrow viability as assessed by colony forming unit-granulocyte macrophage assay (CFU-GM) and found that human bone marrow exposed to nitrous oxide experienced no significant difference in viability. Both papers concluded that use of nitrous oxide in patients undergoing bone marrow donation is not contraindicated.
Dr. J. Gross and colleagues from the University of Connecticut examined the effects of midazolam and diazepam on SaO2 during conscious sedation. Using a randomized, double-blind study technique on 86 patients, they found that equi-sedating doses of these two drugs significantly reduced SaO2 for up to 80 minutes, and that there were no significant differences between the drugs at any time during
the study period. Both drugs caused SaO2 to fall below 85% in some patients breathing room air. They concluded that midazolam (compared to diazepam) did not appear to increase the risk of hypoxemia during conscious sedation, but that both held the potential to cause significant desaturation. They emphasized the need for careful monitoring of patients sedated with either drug.
Hct Doesn’t Help
Dr. M. Bodner and associates at Washington University in St. Louis examined the relationship between cardiovascular morbidity and perioperative hematocrit (Hct) in patients undergoing radical prostatectomy. They found that there was no significant difference in the lowest documented Hct in patients who had cardiovascular morbidity and those who did not, thus negating the predictive value of patient hematocrit. With increasing awareness of viral transmission during blood transfusion, this study would support a more cautious approach to transfusion timing.
Two presentations dealt with patient recall during anesthesia. The first, by Dr. M. Clemency and associates of Emory University, examined the incidence of recall of surgery following anesthesia for trauma. They found an overall rate of recall of 5% (less than in previous studies in this patient population), but when data were stratified by .minutes without anesthesia’ the results showed (not unsurprisingly) that those patients with more than 15 minutes of no anesthesia had a higher incidence of recall than those with less (33% vs. 2%). Surprisingly, the incidence of recall did not appear to be influenced by the use of amnestics, although numbers examined were quite small. They urged further study of the effectiveness of amnestics in anesthesia for trauma. The second study, by Dr. W. Gild (University of Washington, Seattle) and associates in the Closed Claims Project, examined liability aspects of recall following surgery and unintentional administration of muscle relaxants to awake patients. They found a 2% incidence of recall and awake paralysis in the Closed Claims Data Base (n m 2400). Thirty-three of the claims involved recall of intraoperative events (recall), while 12 resulted from unintentional administration of muscle relaxants to awake patients (awake paralysis). Award amounts for all these claims were significantly less than for other claims in the data base ($10K vs. $95K), standard of care was judged (by peers) to have been met less frequently in the awareness claims than others (24% vs. 44%), and no consistent pattern of causation could be discerned in the recall subgroup of claims. The awake paralysis claims involved simple lapses of vigilance and carelessness. The study underscores present lack of understanding of the etiology of the awareness and recall of events during general anesthetics.
Dr. B. McGrath and coworkers at George Washington University studied the incidence of pulmonary embolization from pneumatic tourniquet use during orthopedic surgery using transesophageal echocardiography. Evidence of ‘solid’ emboli was seen in 5 of the 22 patients studied (all following deflation of the tourniquet). Patients with embolization suffered no significant changes in BP or 02 saturation. They found that embolization following deflation of lower leg tourniquet is a relatively common event (23%) and was seen independent of whether marrow cavities were entered. They thus concluded that the solid emboli seen were venous thrombi and called for further study to determine the nature and significance of emboli and the potential effectiveness of anti-thrombus prophylaxis.
Predicting Difficult Intubations
Dr. J.S. McDonald and colleagues from Ohio State University studied 1,501 patients who underwent laryngoscopy and intubation. In each of these patients, visualization during laryngoscopy was graded on a scale of 1-4 (I being good visualization and 4 being very poor). They then recorded eight factors on each patient to see if the difficult intubations could be predicted from these physical signs. The factors included: visualization of tonsillar pillars, mentum-suprahyoid distance, mentum-sternal notch distance, oral opening distance, range of neck motion, body habitus, receding mandible, and buck teeth. These characteristics were scored on a form during the preoperative visit. Seventy-nine patients (5.3%) were felt to have a larynx that was difficult to visualize (Grade 3) and 23 patients (1.5%) were felt to have a larynx that was very difficult to visualize (Grade 4). Several different analyses performed to determine if there was a relationship between any single factor or group of factors and the visualization score failed to reveal any consistent relationship. The authors also noted that 12 cases (1%) had oxygen saturations of less than 90%. They concluded that anatomic scoring methods used to prospectively predict difficult intubations are largely unreliable as screening tools.
Fire in the Operating Rooms
Dr. R. Westerlund from New York University Medical Center reported on the problems encountered when a fire broke out during a neurosurgical procedure when a hand-held laser was accidentally discharged while aimed at the operating room drapes. The fire produced dense acrid smoke that forced everyone out of the room in less than two minutes. The patient was fixed to the table with pins and could not be moved, and visibility in the room was near zero.
In reviewing the experience, the author developed some important general guidelines. First, do not assume that a fire cannot occur in your operating room. Instead plan ahead and think about what would have to be done if a fire did take place. It is important to know the types and locations of fire extinguishers in the operating room, as different fire extinguishers have different uses. For instance, halon can be used around electronic equipment, but it consumes oxygen in the room. Carbon dioxide leaves granular particles. The locations of alarm boxes, gas shut off valves, and emergency equipment should be known by all personnel. Auxiliary lighting, such as flashlights, and fire blankets should be available.
Some general safety precautions should also be followed. There should be stringent rules for control of sources of ignition (i.e., lasers, electrocautery and hot fiberoptic cords). Keep ignition sources away from flammable solutions and combustible material. Use of laser-resistant drapes should be encouraged during these cases. Plan how to remove burning drapes, covers and clothing. Pouring water on an impervious drape will not extinguish the fire as it will continue to burn on the underside of the drape. In these cases, it is necessary to remove the drapes and then attempt to extinguish the fire. It should not be assumed that the fire is entirely out until the entire area is thoroughly inspected.
Personnel should be prepared to react in the presence of heavy acrid smoke. It should not be assumed that one can function normally in the presence of a smoke filled room, as the heavy smoke may make it impossible to see or breathe. During a fire, personnel may be forced to leave the O.R. without being able to help the patient. Do not assume that the ventilation system will clear the smoke. Most ventilation systems have smoke detectors which shut off the exhaust to that room in the event of a fire. Care for the anesthetized patient in a hazardous environment is something that requires a great deal of advanced preparation.
Lower Extremity Nerve Injury in the Lithotomy Position
Drs. M. Warner and J. Martin of the Mayo Clinic reviewed more than 1,000,000 entries in the Mayo Clinic database of surgical cases performed from 1957-1992 to try to determine the incidence of lower extremity nerve injury in the lithotomy position. The records were scanned for 56 surgical procedures historically done in the lithotomy position, resulting in 198,000 cases which were further examined using ICD*2*CM diagnosis codes for 26 different nerve injuries and four compartment syndromes. To be classified as a persistent nerve injury, a motor deficit had to be present for greater than three months’ duration, and the compartment syndrome was defined as the presence of the diagnosis plus fasciotomy.
The authors found 922 patients; 59 were determined by three independent anesthesiologists to have complications related to their procedure in the lithotomy position. Of these 59 patients, 54 (1:3,675) had persistent nerve injury while five patients (1:39,692) had compartment syndromes. Although preliminary data do not identify mechanisms of injury, many potential factors are possible. The authors are currently involved in study of these 59 patients to determined the relative contribution of various factors to nerve injury in the lithotomy position. The authors further extrapolated their data to say that approximately 500 cases of persistent nerve injury and 50 cases of compartment syndrome could be expected in the U.S. each year from surgery in this position.
Can Simulation Accelerate the Learning of Basic Anesthesia Skills?
Dr. M. Good and colleagues from the University of Florida studied 26 residents just beginning their anesthesia training to determine whether basic anesthesia skills taught in a simulator would accelerate learning over the conventional lecture format. The residents were divided into two groups and every day for two weeks the residents either attended a lecture or trained in the simulator. There were 10 learning objectives which included checking and operating the anesthesia machine and ventilator, inducing general anesthesia, managing emergence and reversal of muscle relaxants, and diagnosing and treating hypoxemia. The residents were evaluated on the basis of a ‘multiple choice test and by evaluations of their critical performance by the faculty.
The pre-test and post-test did not show any significant difference between the two groups. However, at Week 3 the change in the clinical evaluation scores in the simulator group were significantly better than those in the didactic group, but by Week 13 the two groups were equal in their clinical evaluation scores. The authors concluded that teaching basic anesthesia skills to new residents by use of an anesthesia simulator can accelerate initial learning when compared with the traditional lecture format.
Airway Management Issues
Several papers addressed airway management. Dr. R. From and associates from the University of Iowa presented their evaluation of ‘Sim I,’ an interactive computerized learning program for airway management developed for use in ACLS courses, in teaching medical students during their third year anesthesia clerkship. Students received either the traditional preclinical instruction on airway management from department faculty or utilized Sim 1 without faculty interaction, and then their airway management skills were evaluated when they got to the operating room. There was no difference between the two groups in the degree of difficulty managing airways by faculty evaluations or by their own evaluations, nor was the students’ level of satisfaction different. The investigators conclude that the simulation program is no more effective than faculty instruction in introduction to airway management, and are not utilizing this technology in their clerkship program.
Two papers discussed the laryngeal mask airway (LMA). Dr. J. Pennant and colleagues from the University of Texas, Southwestern, evaluated this device as a method of initial airway management in patients presenting with a possible cervical spine injury in a rigid collar. Placing a rigid collar on normal volunteer patients prior to inducing anesthesia, they compared the time to airway securement after induction of anesthesia and paralysis utilizing the LMA or conventional laryngoscopy and intubation. They found the LMA to allow faster and easier positive pressure ventilation. They believe this device should be used when endotracheal intubation is difficult or impossible in patients with possible cervical spine instability and there is an immediate need for oxygenation and/or ventilation, even though it does not reliably protect the airway from aspiration.
Dr. M. Maroof and associates from King Fahad National Guard Hospital in Riyadh, Saudi Arabia, reported their modification to the LMA which allows it to be used as a route for fiberoptic intubation (FOI) with adult size endotracheal tubes. By removing the pliable grates at the opening and slitting the device lengthwise along its entire length including the cuff, they were able to insert the endotracheal tube through it and then remove the LMA from around the tube. Without the lengthwise slit, only a size 6 or smaller tube can be inserted over a fiberoptic scope and the device has to remain taped in place until the endotracheal tube is removed. This group tested the modified MLA as an aid to fiberoptic intubation (FOI) by comparing time to successful intubation with and without the device by experienced and inexperienced operators. Using the device hastened intubation for both experienced and inexperienced and markedly increased the success rate for those inexperienced in the technique of FOI. From these two reports, it appears that the LMA can play a significant role both in enhancing patient safety and teaching skills of fiberoptic intubation.
Dr. K. Davis, Wilford Hall U.S.A.F. Hospital in San Antonio, reported results of a survey to determine the prevalence of skills in fiberoptic intubation (FOI) among anesthesiologists in the U.S. Teaching hospitals have more fiberoptic intubating bronchoscopes, use them more often, and feel they are more necessary than non-teaching hospitals. Academic faculty and senior residents report a higher success rate and feel more capable with FOI than do anesthesiologists in non-teaching hospitals. Dr. Davis concludes that if an anesthesiologist is not able to acquire confidence and skill in this technique during residency, it is unlikely that he or she will be able to pick it up later.
Drs. S. Marsch and H. Keller report from the University of Basel, Switzerland, that in that country FOI occurs three times more often in teaching than non-teaching hospitals. Because electively performing oral FOI after induction of anesthesia and paralysis is an excellent means of acquiring this skill, they determined if there was a difference in patient hemodynamic profile or postoperative morbidity using FOI as compared to conventional laryngoscopy and intubation. Four third-year residents without previous FOI experience were instructed in the technique with a video introduction and extensive practice on a mannequin. They then performed FOI on 10 patients and 10 conventional intubations, at which they were considered expert, in random sequence. FOI took significantly longer than conventional intubation for these novices (average 76 vs. 20 seconds), but hemodynamic data were recorded on each patient and there was no difference in the profiles using either intubation technique. There was also no difference in the incidence of postoperative sore throat, dysphagia, or hoarseness with the two techniques. The authors conclude that it does not compromise patient safety to learn this technique by elective FOI after induction of anesthesia.
The Anterior Orifice
Confirming endotracheal intubation was addressed in two papers. Drs. W. Gentry and C. Shanks from Northwestern University described the Ford Maneuver using the Miller laryngoscope blade. In this maneuver after the endotracheal tube is positioned (hopefully) in the trachea and while the laryngoscope is still in place, a simple dorsal push of the tube in the pharynx while exerting ventral pressure on the laryngoscope brings the larynx into view so that the position of the tube passing between the vocal cords can be directly viewed. They evaluated this maneuver’s efficacy in improving the Cormack and Lehane grade for larynx visualization after intubation in 94 patients and found that it improved the grade in 71% of patients. The Ford Maneuver had previously been evaluated only using the MacIntosh blade.
Dr. R. Salem and associates from Illinois Masonic Medical Center in Chicago described another simple means of testing for endotracheal tube placement using a self inflating bulb from an asepto syringe. After tube placement, the bulb is deflated and attached to the endotracheal tube. If the tube is in the esophagus, the bulb will not reinflate. If the tube is in the trachea, it will. This group tested the efficacy of the bulb in identifying esophageal intubation in the presence of a nasogastric tube, and found that it still led to no false positive conclusions. Dr. Salem points out that there still might be false negatives, when the tube is in the trachea but the bulb does not inflate. In cases where the tube is linked, there is severe distal airway obstruction, or the diaphragm is moving and creating negative airway pressure.
The pathogenesis of carbon monoxide production in anesthesia circuits was investigated by Dr. R. Moon and colleagues from Duke University. Postulating that fluroform in association with sodalime might be responsible for the formation of CO, this group passed fluroform and the three inhalational anesthetics through sodalime canisters at slow flows for 4-8 hours, then the canisters were allowed to sit overnight. They were flushed with air the following morning and the effluent gas analyzed for CO. The level of CO did increase with the passage of inhaled agents and fluoroform through sodalime, but not to the high levels occasionally reported in the literature. The authors conclude that passage of fluorinated hydrocarbons through sodalime does produce some CO in the circuit, especially after the canister sits for a period of time, but that some other mechanism must also be involved. They recommend using high fresh gas flows (>5 LPM) during anesthetic administration, frequent changes of C02 absorbent canisters, and flushing the circuit before using it after it has sat idle for a time.
Dr. A. Wong and his group from the Hospital for Sick Children in Toronto investigated the cause of airway fires during tonsillectomy, studying the contributions of an oxygen enriched atmosphere in the pharynx, N20, and the presence of saline, epinephrine and bismuth on the tonsillar packs. Measuring oxygen concentrations in the pharynx of children undergoing tonsillectomy, they found that >21% oxygen occurred when uncuffed tubes were used with controlled ventilation. Reproducing the environments they found in the pharynx in bell jars, they tried to ignite cotton packs soaked in saline, in epinephrine and in epinephrine and bismuth with diathermy. The results showed that the presence of an enhanced oxygen atmosphere increases combustibility of the packs no matter what they are soaked in. The dryer the packs become, the more likely they are to ignite in an oxygen enhanced environment. Finally, addition of bismuth to the packs significantly increases combustibility. Efforts to prevent fires should include limiting leaks around the endotracheal tube by using spontaneous ventilation and keeping the packs wet.
Post op Airway
Evaluating, retaining, and treating the airway after extubation is critical, especially if the post operative airway cannot be manipulated. Drs. R. Cooper and S. Levytam from Toronto Hospital have developed a 65 cm catheter that can be placed through the endotracheal tube and is well-tolerated when left in situ after extubation. This tube can be used for gas aspiration and capnography, insufflation of 02, or jet ventilation. A spiral pattern of side-holes at the distal end of the catheter allows jet ventilation without catheter whip. The authors reported on 51 patients in whom it had been used. Capnography and oxygenation were the two most common applications. Jet ventilation was feasible, but barotrauma is still possible, especially if the upper airway is obstructed.
Safety of procedures continues to be a major focus of investigations both in the USA and abroad. The threat of a major vein perforation even days after the placement of a CVP or multi-lumen catheter into a central vein limits the usefulness of ft route of venous access, especially on the general nursing floor. Drs. R. Blackshear and N. Gravenstein from the University of Florida have examined five different catheter types regarding their potential to perforate a membrane in an in vitro testing situation. Catheters having rounded tips rather than beveled tips were much less likely to perforate. Some of the catheters which perforated the in vitro membrane easily had also been associated with in vivo perforations in the authors’ institution.
The safe use of a drug depends on careful attention to known safety policies, one of which is the use of a test dose anytime a potentially toxic dose of local anesthetic is injected. Dr. Y. Auroy et al. from Clamart, France queried French anesthetists working in surgical centers performing upper limb surgery under axillary block. They found a higher than expected neurologic and cardiovascular toxicity rate. More importantly, these experienced anesthetists were careful to aspirate and inject the anesthetic slowly but rarely used a test dose, as was the routine practice in performing epidurals. In another presentation, the safety of epidural anesthesia by residents was analyzed by Dr. J. Naulty et al. from George Washington University. Prospectively following 10 residents and analyzing Ql forms and anesthesia records showed that unintended dural punctures fell from 5% to 1% over three years and the need to replace an epidural catheter because of inadequate anesthesia fell from 7% to 2%, but the incidence of IV placement of the epidural catheter did not change with time, remaining steady at 4% over the training period. This further indicates the importance of a test dose to seek evidence of intravascular placement of either needle or catheter.
Perioperative heat loss continues to be a topic of concern. Dr. M. Barhorst et al. from the Mayo Clinic examined the temperature fall in patients transported from the OR to the PACU (4.6 minutes average time). Patients having continuous epidural anesthesia were colder at the end of surgery (34.80 C by tympanic membrane probe) than were the patients given general anesthesia (35.6o C). The epidural group temperature fell 0.3′ C while the general anesthesia group temperature fell 0.1 Co. Such differences in core temperature seem small, but Dr. C. Sheffield et al. from the University of California, San Francisco suggest that mild hypothermia of 30 C may significantly alter resistance to infection. They anesthetized guinea pigs for 6 hrs each, maintaining normal core temperature in 12 and 30 C low in 12 others. Three doses of S. Aureus were inoculated intradermally after two hours. Four days later, at the sites of the greatest inoculum, the bacteria from the normothermic animals had decreased by 50% while the bacterial count from the sites from the hypothermic animals had increased slightly.
Effectiveness of monitoring practices was also studied. Knowing error patterns of commonly used and relied-upon monitors is a needed feature of safety research. Dr. S. Barker et al. from the University of California, Irvine, examined the responses of five different pulse oximeters when placed deliberately half-on the finger or ear lobe but still recording pulse accurately. The saturation readings were significantly in error but not necessarily predictably so. The pulse oximeter should be in a position that the anesthetist can frequently check it or reposition it if artifactual readings occur. Dr. G. D’Honneur et al. from Creteil, France, examined the precision and bias of two commonly used neuromuscular stimulation techniques (train-of-four and double-burst) in evaluating neuromuscular recovery after reversal of muscle relaxants. recording pulse accurately. The saturation readings were significantly in error but not necessarily predictably so. The pulse oximeter should be in a position that the anesthetist can frequently check it or reposition it if artifactual readings occur. Dr. G. D’Honneur et al. from Creteil, France, examined the precision and bias of two commonly used neuromuscular stimulation techniques (train-of-four and double-burst) in evaluating neuromuscular recovery after reversal of muscle relaxants. 200 patients who had had abdominal surgery were examined immediately after arriving in the recovery room. Double-burst simulation was more precise at recovery levels of TOF 40-70%, which is the important section of the neuromuscular recovery curve in the recovery room. At either end of the recovery spectrum, however, the two monitoring methods were equivalent.
An example of reluctance to follow directions was reported by Dr. M. Roizen et al. in a multicenter report regarding the phase IV post-marking study of propofol. The use of the drug was to start with induction doses only and proceed to induction and maintenance by intermittent injection and finally to TIVA by infusion. The study revealed that the drug was usually used on fairly healthy patients (healthier than the usual surgical population). However, occasional practitioners used it very quickly on older, sicker patients with resulting hypotension and bradycardia, and a number of practitioners began the third step of the phased use before finishing the first or second. The analysis indicated that generally the bulk of anesthesiologists are conservative in the early use of a new drug.
Conscious sedation by either midazolam or diazepam was shown to be equally depressing to SpO2 during conscious sedation (Dr. J. Gross, University of Connecticut), and direct feed-back from a capnograph was shown to improve the efficiency of CPR as measured by higher C02 elimination (Y. Lambert et al., Creteil, France)
Postoperative complications were addressed in two papers. Dr. B. Grundy and associates from the University of Florida utilized telemetered pulse oximetry on the surgical ward to determine if frequency and severity of postoperative hypoxemia could be predicted by any patient or surgical factors. Not surprisingly, obesity (>120% ideal body weight) correlated most strongly with preoperative episodes of SaO2 <90%, but only weakly predicted the severity of postoperative episodes. The greatest predictor of postoperative desaturation episodes was major abdominal surgery, followed distantly by inguinal herniorrhaphy, neurosurgery and superficial procedures in that order. There was no correlation with ASA physical status, age or smoking history. Desaturation episodes were more likely in patients who had received general as contrasted with regional anesthesia. Episodes of desaturation were not confined to the first few nights after surgery and tended to be more severe the later they occurred. Supplemental oxygen therapy did not prevent the episodes. Dr. Grundy and her group continue to utilize this technology and linear analysis to perfect a system to predict who should receive intervention to prevent episodes of postoperative hypoxemia, which they speculate may account for at least part of the cognitive dysfunction reported in some postoperative patients.
Dr. S. Kaseno and colleagues from Hokkaido University In Sapporo, Japan, retrospectively compared a battery of liver function tests in patients who received sevoflurane or isoflurane anesthesia during a 12-month period beginning in September, 1990. They excluded all patients who had preoperative alterations in hepatic or renal function, who received a combined regional and general anesthetic, who received blood products perioperatively, or who had cardiovascular, thoracic or abdominal surgery. There were about 100 patients who received each anesthetic and did not differ in any characteristics. Patients receiving isoflurane showed minimal effects on every liver function test. Patients receiving sevoflurane exhibited significantly higher values for AST, ALT, gammaGTP and LAP than did those receiving isoflurane from 7 to 28 days postoperatively. These elevations correlated with the duration of exposure to the agent. LAP and ALT values were outside the normal range at 14 days for the group receiving sevoflurane, but there was no evidence of clinical liver dysfunction. Bilirubin levels did not change in either group. The impact of this and similar studies on the use of Sevoflurane in this country remains to be seen.
Open Packages Safe
In the arena of cost containment, we were told by a group from the University of South Carolina led by senior medical student M.W. Moore that we can use endotracheal tubes up to at least five days after we open the package and test the cuff, if we don’t take the tubes out of their packages and get them dirty. These investigators cultured tubes from opened packages stored in carts of their least and most busy operating rooms at 24, 48 and 120 hours by swabbing them on a blood-agar plate and then immersing them in thioglycolate broth. Neither culture method showed any growth for any tube. The investigators speculate that they can save their department at least $21,000 per year by not discarding all tubes in opened packages at the end of a day, so long as they are careful to keep them clean.
There were several posters summarizing studies about the safety of the anesthesiologist. Dr. A. Tait of the University of Michigan mailed a questionnaire to 70 anesthesiologists at four hospitals asking about their compliance with CDC guidelines for the prevention of HBV and HIV transmission to these practitioners. Forty-seven percent reported having suffered 1 to 2 needlesticks during the previous year. Sixty-three percent admitted to frequently recapping needles; only 6% said they never did so. The figures for those who wore gloves are also remarkable e.g. only 56% wore them even when contact with the patient’s blood was a possibility. Nevertheless 50% reported that they had altered their habits since the AIDS scare. The author reminds us it is estimated that 40% of all occupational HIV transmission could have been avoided by proper disposal of needles and by following CDC guidelines.
Dr. A. Rosenberg and colleagues from New York University mailed a questionnaire to a random 10% sample of ASA members and got answers from 1,367 anesthesiologists. They also noted considerable improvement in self protective habits. There was a decrease in reuse of syringes containing drugs such as vasopressors which can be available for several consecutive patients. Residents were better than attendings at wearing gloves when starting IV or arterial lines. During the period of the study, 8.5% of the residents and 3.7% of the attendings sustained needle-sticks while taking care of patients known to be HIV positive.
Drs. W. Merritt and A. Zuckerberg at Johns Hopkins Hospital studied contamination of the anesthetic record. At first blush one would imagine that this refers to such heinous activity as ‘smoothing’ of notations of vital signs on the anesthetic record. Their study must be taken literally; for on their poster they displayed an anesthetic record with splashes of dried blood. They found that 51 % of the records of anesthetics for CABC and abdominal aneurysm operations were contaminated. Even 15% of those for laparoscopic cholecystectomy were also affected. There war,-‘ some correlation to the frequency of lab specimens ‘I drawn from the patients and number of units of blood administered. They could not always find a mechanism but suggest that increased vigilance, frequent glove changes and hand washing, innovative blood sampling techniques and the use of automated record keeping might diminish this potential hazard to the anesthesiologist.
Dr. M. Williams et al. from the University of Colorado conducted a pilot study to see if physician addicts had any difficulty returning to abstinence after they had had operations which required them to receive sedatives or narcotics. They got their information from the directors of five state recovery programs and received 51 completed replies. Approximately half were ex-alcoholics and the rest were former drug addicts. The mean preoperative period of abstinence was four years. Close to 30% of the former drug addicts developed cravings for their former drug of choice and experienced emotional lability and the need for supportive care whereas only 7.4% of alcoholics relapsed. The authors conclude that even years after recovery addicts may be at risk for relapse if exposed to sedatives or narcotics given for surgical indications.
Lastly, Dr. J. Zacny and associates wondered if propofol had the potential to become a drug of abuse. They studied the subjective effects of subanesthetic dose infusions in 10 volunteers and performed a double blind randomized cross-over study using the vehicle for propofol, Intralipid, as a control. Five of the subjects liked the real thing whereas most of the group on receiving the vehicle were neutral about its effects. The authors conclude from this preliminary study that propofol may have some potential for abuse.
In all, the diverse and extensive spectrum of safety-related presentations at this year’s meeting illustrates yet again that patient safety issues have become a very significant component of anesthesia practice.
Dr. Aukburg, University of Pennsylvania, is a member of the Newsletter Editorial Board. Dr. Ehrenwerth, Yale University, is a member of the Board of Directors of the APSF and a member of the Newsletter Editorial Board. Dr. Gild, University of Washington, chaired one of the ASA scientific sessions, as did Dr. Polk, who is from the University of Chicago; Dr. McGee, Northwestern University is from Evanston (IL) Hospital, and Dr. Zeitlin of the Brigham and Women’s Hospital and Harvard in Boston is a Newsletter Associate Editor.