Anesthetic management of patients receiving calculus therapy with a third-generation extracorporeal lithotripsy machine

We reviewed the anesthetic requirements for satisfactory use of a third-generation electromagnetic-source design for extracorporeal shockwave lithotripsy (SWL). Medical records were reviewed for a period of 9 months on all patients receiving anesthesia care for SWL with and without other urologic procedures. The Modulith SL20 was used on 56 ASA Class I-III patients having 87 SWL treatments. Demographic and anesthetic variables were recorded. Complications documented included dysrhythmias, nausea necessitating treatment, and conversion from sedation to regional or general anesthesia. The majority of procedures (83%) were performed on an outpatient basis. Patients were classified as ASA physical status I (27%), II (63%), or III (10%). Monitored anesthesia care with intravenous sedation was utilized in 93% of cases. Of these cases, 78 involved a combination of intravenous propofol, fentanyl, and midazolam; the remaining 3 involved propofol, alfentanil, and/or midazolam. The mean treatment duration was 36 minutes. Patients were discharged within 1 hour after procedure completion in 77 cases (89%). Nausea necessitating treatment was rare (3%). The mean dose of propofol administered with SWL as the only procedure was 272 +/- 112 mg. When SWL was combined with other urologic procedures, the mean dose of propofol was 334 +/- 121 mg. Continuous intravenous propofol infusion provides excellent procedural conditions for SWL on the Modulith SL120, a third-generation lithotripter.

The anesthetic management of a patient with chromosome 10qter deletion syndrome

Terminal deletions of chromosome 10q are uncommon. The resulting syndrome includes cardiac and facial anomalies, urogenital abnormalities, limb defects, and mental retardation. Most affected infants require surgical correction of these anomalies. Presented are features inherent in the syndrome that will aid the anesthesiologist in the perioperative management of such patients.

An assessment of the duration of cephapirin-induced coagulation abnormalities as measured by thromboelastography

Cephalosporin antibiotics are used prophylactically in cardiothoracic surgery to prevent postoperative infection. In 30 patients undergoing primary elective coronary artery bypass grafting, the whole blood coagulation system was prospectively evaluated before, and 10 and 30 minutes after administration of 1 g of cephapirin (Cefadyl, Bristol Laboratory, Evansville, IN). All patients had normal preoperative coagulation studies and had not received anticoagulant or antiplatelet therapy within 7 days of surgery. At 10 minutes after cephapirin administration, 23 of 30 patients had a significant change in all phases of whole blood coagulation as monitored by thromboelastography (TEG). Thirty minutes after cephapirin administration there was no statistical difference compared with the baseline TEG. It is concluded that cephapirin can cause a significant but transient change in the viscoelastic properties of blood. Coagulation parameters of the TEG should be measured prior to cephapirin administration to prevent errors in establishing baseline values prior to cardiopulmonary bypass.

Effect of partial neuromuscular blockade on intraoperative electromyography in patients undergoing resection of acoustic neuromas

Intraoperative electromyographic monitoring of the facial nerve during acoustic neuroma excision provides early detection of nerve injury and improved outcome. To determine whether a useful level of peripheral neuromuscular blockade could be achieved without compromise of facial electromyographic monitoring, we studied 10 patients undergoing resection of acoustic neuroma. Facial nerve monitoring was accomplished by placement of wire electrodes in the orbicularis oris, orbicularis occuli, and mentalis muscles. Peripheral neuromuscular blockade was assessed by recording unprocessed hypothenar compound muscle action potentials (CMAPs). After induction of anesthesia, an infusion of atracurium (1.0 micrograms.kg-1.min-1) accompanied by a bolus dose of 50 micrograms/kg was administered. The infusion was then increased in increments of 0.5 micrograms.kg-1.min-1 until a 50% reduction in hypothenar single-twitch CMAP was obtained. Facial nerve function was continuously monitored by comparison of facial CMAPs produced by stimulation of the nerve proximal and distal to the tumor bed. The mean (+/- SD) infusion rate of atracurium was 2.55 +/- 0.75 micrograms.kg-1.min-1. Decrements in facial nerve CMAPs were detected in 6 of 10 patients, and all demonstrated moderate to severe facial nerve dysfunction. In no patient was an unexpected deficit present postoperatively. Moderate degrees of peripheral neuromuscular blockade can be achieved without compromising facial nerve electromyographic monitoring.

The modified Fontan procedure: physiology and anesthetic implications

The modified Fontan operation has gained wide acceptance as a functional corrective procedure for patients with CHD with single ventricle physiology. Long-term survival and palliation of symptoms are excellent with most patients able to lead normal lives. The absence of a pulmonary contractile ventricle means that the single ventricle is responsible for perfusion of both the pulmonary and systemic circulations. Elevated systemic venous pressure is required to overcome PVR and this state of systemic venous hypertension has a significant impact on the anesthetic and postoperative care of these patients.

Method of intraoperative monitoring of neuromuscular function and residual blockade in the recovery room

We evaluated the method used intraoperatively to assess the degree of neuromuscular blockade prior to pharmacologic reversal to determine its role in preventing residual blockade in the postanesthesia care unit (PACU). We studied 38 patients who received a nondepolarizing muscle relaxant during general anesthesia for carotid endarterectomy or thoracotomy. The anesthesiologist assessed the degree of neuromuscular blockade intraoperatively prior to pharmacologic reversal either by the standard method of visually counting the number of evoked thumb twitches elicited by supramaximal train-of-four stimulation of the ulnar nerve (i.e., thumb train-of-four count), or by an alternative method such as 1) visually counting the number of evoked orbicularis oculi muscle twitches elicited by supramaximal train-of-four stimulation of the facial nerve, or 2) observing the patient for clinical evidence of partial recovery (e.g., swallowing or attempts to breathe). Residual blockade in the PACU was defined as 1) a train-of-four ratio less than 0.70 (measured by a mechanomyograph), or 2) the inability of the patient to perform clinical tests of neuromuscular function (e.g., a sustained head lift for 5 seconds) and evidence of neuromuscular weakness that was resolved following administration of edrophonium. Five of the 22 patients (23%) in whom one of the alternative methods was used had residual blockade in the PACU; none of the 16 patients with a thumb train-of-four count of 3 or 4 before pharmacologic reversal of NMB had residual blockade in the PACU (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The role of desmopressin acetate in patients undergoing coronary artery bypass surgery. A controlled clinical trial with thromboelastographic risk stratification

The role of desmopressin acetate in attenuating blood loss and reducing homologous blood component therapy after cardiopulmonary bypass is unclear. The purpose of this investigation was to identify a subgroup of patients that may benefit from desmopressin acetate therapy. One hundred fifteen patients completed a prospective randomized double-blind, placebo-controlled trial designed to evaluate the effect of desmopressin acetate (0.3 microgram.kg-1) on mediastinal chest tube drainage after elective coronary artery bypass grafting surgery in patients with normal and abnormal platelet-fibrinogen function as diagnosed by the maximal amplitude (MA) on thromboelastographic (TEG) evaluation. The 115 patients evaluated were divided into two groups based on the MA of the post-cardiopulmonary bypass TEG tracing. Group 1 (TEG:MA greater than 50 mm) consisted of 86 patients, of whom 44 received desmopressin and 42 received placebo. Twenty-nine patients had abnormal platelet function (TEG:MA less than 50 mm) and were designated as group 2. In group 2, 13 received desmopressin and 16 placebo. During the first 24 h after cardiopulmonary bypass, the placebo-treated patients in group 2 had significantly greater mediastinal chest tube drainage when compared to placebo patients in group 1 (1,352.6 +/- 773.1 ml vs. 865.3 +/- 384.4 ml, P = 0.002). In addition to increases in blood loss, group 2 placebo patients also were administered an increased number of blood products (P less than 0.05). The desmopressin-treated patients in group 2 neither experienced increased mediastinal chest tube drainage nor received increased amounts of homologous blood products when compared to those in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Narcotic-induced histamine release: a comparison of morphine, oxymorphone, and fentanyl infusions

This study, using an improved histamine assay, repeated previous studies that demonstrated large doses of morphine for induction of anesthesia in patients undergoing coronary artery bypass grafting were associated with histamine release. Thirty randomized patients received infusions of either morphine, 1 mg/kg, oxymorphone, 0.2 mg/kg, or fentanyl, 50 micrograms/kg, over a 10-minute period for induction of anesthesia prior to surgery. There were no significant changes in plasma histamine levels in individual patients or among drug groups. The discrepancy between the present histamine results and those previously reported using similar protocols is due, in part, to variations in plasma histamine measurements that can occur using the less reproducible, older assays for histamine. During routine inductions, large doses of morphine, oxymorphone, or fentanyl administered by infusion do not appear to stimulate release of clinically significant plasma levels of histamine.

Effects of referral bias on surgical outcomes: a population-based study of surgical patients 90 years of age or older

During the 11-year period 1975 through 1985, 1,063 surgical procedures were performed on 795 Mayo Clinic patients 90 years of age or older. Preoperative conditions, surgical setting, and perioperative morbidity and mortality were analyzed in a comparison of the local residents of Olmsted County, Minnesota (N = 224), with patients from outside the county but within 250 miles (N = 456) or referrals from a distance of 250 miles or further (N = 115). In comparison with non-Olmsted County patients, Olmsted County patients were generally older, had more preoperative chronic diseases, and underwent more emergency operations. Patients who had traveled 250 miles or more to the Mayo Clinic were more likely to be men and referred for cancer-related surgical procedures. The risks of major morbidity and mortality within 48 hours postoperatively were increased in patients with more preoperative chronic diseases and those undergoing emergency procedures, characteristics most common in Olmsted County patients. Because of differences in these factors between groups, perioperative risks averaged over our entire patient series underestimated risks that would be expected from a population-based cohort such as Olmsted County residents. In general, data from tertiary medical centers probably do not accurately reflect overall practice or outcomes in community settings.

Right ventricular outflow construction for complex congenital cardiac malformations without cardiopulmonary bypass: management and outcome of 44 patients

A review of surgical and anesthetic techniques used in 44 consecutive patients to establish continuity between the right ventricle and pulmonary circulation, without extracorporeal circulation, as a first-stage repair in a variety of selected complex congenital cardiac lesions with right ventricular outflow obstruction, is presented. The overall operative mortality rate was 9% (four deaths), but no deaths occurred in the last 24 patients. Eleven patients (27.5%) have subsequently undergone complete repair and one patient (2.5%) underwent a Fontan repair. The advantages, anesthetic concerns, complications, and outcome are discussed.

A comparison of washed red blood cells versus packed red blood cells (AS-1) for cardiopulmonary bypass prime and their effects on blood glucose concentration in children

The effects on blood glucose concentrations of packed red blood cells (AS-1) (group I) versus washed red blood cells (group II) for cardiopulmonary bypass prime were compared in 20 infants weighing less than 10 kg undergoing cardiac surgical procedures. All patients were anesthetized with N2O/O2/isoflurane/fentanyl and received lactated Ringer's solution prior to bypass. Blood glucose concentrations prior to bypass were 85 +/- 15 mg/dl (mean +/- SD) in group I and 81 +/- 14 mg/dl in group II. Blood glucose concentrations were 210 +/- 21 mg/dl versus 78 +/- 14 mg/dl (P less than 0.001) 10 min after initiation of bypass, 241 +/- 48 mg/dl versus 107 +/- 28 mg/dl (P less than 0.001) prior to separation from bypass, and 214 +/- 52 mg/dl versus 97 +/- 19 mg/dl (P less than 0.001) after protamine administration in group I and group II, respectively. The use of washed red blood cells for cardiopulmonary bypass priming solution in infants significantly attenuates the increase in blood glucose concentration otherwise observed during cardiopulmonary bypass.

Evaluation of a forced-air system for warming hypothermic postoperative patients

Thirty adult surgical patients admitted to the recovery room with an oral temperature less than or equal to 35.0 degrees C were randomized into two groups. Group 1 patients were covered with cotton blankets warmed to 37.0 degrees C, and group 2 patients were treated with a forced-air warming system. Mean oral temperature on admission to the recovery room was the same in both groups (34.3 degrees C). Oral temperature and the presence or absence of shivering were recorded at 15-min intervals. After application of the selected warming method, patients in group 2 were warmer at all time intervals. Mean temperatures in the forced-air heating group and in group 1 were, respectively, 34.8 degrees C and 34.3 degrees C (P less than 0.05) at 15 min; 35.0 degrees C and 34.2 degrees C (P less than 0.01) at 30 min; 35.2 degrees C and 34.5 degrees C (P less than 0.05) at 45 min; 35.8 degrees C and 34.7 degrees C (P less than 0.001) at 60 min; 36.0 degrees C and 35.0 degrees C (P less than 0.01) at 75 min; and 36.0 degrees C and 35.0 degrees C (P less than 0.01) at 90 min. The incidence of shivering was significantly greater in group 1 at 15 and 45 min. In addition, time spent in the recovery room was significantly greater in group 1 than in group 2, 156.0 min versus 99.7 min (P less than 0.003).

Outcomes of surgery in patients 90 years of age and older

During the 11-year period 1975 through 1985, seven hundred ninety-five patients 90 years of age and older underwent operative procedures at the Mayo Clinic, Rochester, Minn. Overall serious morbidity within 48 hours after surgery was 9.4%, and the mortality was 1.6%. The 30-day, 1-year, and 5-year mortality rates were 8.4%, 31.4%, and 78.8%, respectively. Short-term morbidity and both short- and long-term mortality were highly associated with the American Society of Anesthesiologists physical status classification of the patient. Emergency procedures carried a significantly higher risk for morbidity and mortality within the 48-hour period and, to a lesser extent, for long-term mortality. Overall, poorer patient survival was associated with higher American Society of Anesthesiologists class; male sex; preoperative renal, liver, and central nervous system impairment; and surgery on the mouth, nose, or pharynx. When compared with age-, sex-, and calendar year--matched peers from the general population, there was a modest decrease in patient survival at 1 year that reversed by 2 years, with observed survival at 5 years comparable to the rate expected.

Doxacurium chloride for neuromuscular blockade before tracheal intubation and surgery during nitrous oxide-oxygen-narcotic-enflurane anesthesia

The neuromuscular effects of doxacurium (BW A938U) were studied in 36 patients, divided into four groups of 9 patients each, given doxacurium either 50 micrograms/kg (2 x ED95) 5 or 4 minutes or 80 micrograms/kg (3 x ED95) 4 or 3 minutes before tracheal intubation. Adequate neuromuscular relaxation permitted successful intubation at 5 minutes for doxacurium 50 micrograms/kg and at 4 minutes for 80 micrograms/kg. Time to 90% blockade was 5.4 +/- 1.5 minutes for doxacurium 50 micrograms/kg and 3.5 +/- 1.2 minutes for 80 micrograms/kg. Time to 25% spontaneous recovery was 84.7 +/- 54.3 minutes for doxacurium 50 micrograms/kg and 164.4 +/- 85.2 minutes for 80 micrograms/kg. Either neostigmine 45 micrograms/kg, neostigmine 60 micrograms/kg, or edrophonium 1000 micrograms/kg was given for reversal when T1 had spontaneously recovered to 25% of baseline level, T1 being the first response to repetitive train-of-four (TOF) stimuli (2 Hz for 2 seconds at 10-second intervals) expressed as percent of baseline level. The T4:T1 ratio is the amplitude of the fourth twitch relative to the first twitch in a TOF stimulus expressed as a ratio. T1 rapidly achieved 90% of baseline in 5-10 minutes after reversal of neuromuscular blockade. In contrast, the T4:T1 ratio lagged, recovering to a mean of 0.6 at 20 minutes when T1 was over 90% of baseline. Recovery patterns were not statistically significantly different (unpaired t-test) among the three reversal regimens. Therefore, the reversal data were pooled. No clinically significant hemodynamic effects occurred in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaesthesia for patients over 90 years of age. Outcomes after regional and general anaesthetic techniques for two common surgical procedures

Peri-operative morbidity and mortality and long term outcome of patients over 90 years of age who underwent either total hip arthroplasty or transurethral prostate resection were studied retrospectively. The outcomes of patients who received regional or general anaesthesia were compared. One hundred and forty-one patients underwent total hip arthroplasty and 44 patients underwent transurethral prostate resection during the study period (1975-1985). Overall in-hospital mortality was 4.9% Mortality at 30 days was 5.3% in patients who underwent hip arthroplasty during regional anaesthesia, compared with 6.8% in those who received general anaesthesia. Long term survival was similar for these two groups and was longer than projected for age and gender-matched general population cohorts. The 30-day mortality rate was 3.2% for patients who underwent prostatic resection under regional anaesthesia; no deaths occurred in the general anaesthesia group. This difference was not statistically significant. Long term survival was similar for patients in both groups and was better than predicted. Anaesthetic technique did not influence short term morbidity and mortality or long term outcome for these procedures.

Combined H1 and H2 receptor blockade attenuates the cardiovascular effects of high dose atracurium in rabbits

Large doses of atracurium (1.5 mg/kg) (six times the ED95) have been reported to provide adequate conditions for rapid sequence endotracheal intubation within 60 seconds in humans. However, this dose can result in significant histamine release and systemic hypotension. We therefore studied the efficacy of histamine receptor blockade in attenuating this response. Four groups of five rabbits were pretreated as follows: Group I--control, Group II--H1 blockade (1 mg/kg diphenhydramine), Group III--H2 blockade (cimetidine 4 mg/kg), and Group IV--H1 and H2 blockade (diphenhydramine 1 mg/kg and cimetidine 4 mg/kg). All rabbits were anesthetized and then 1.8 mg/kg (six times the rabbit ED95) atracurium was administered. Group I rabbits experienced a decrease in MAP of 12.2 mmHg after one minute, a change that was significantly greater than Group IV in which MAP decreased by 0.8 mmHg (p less than 0.001). H1 or H2 receptor blockade alone was associated with intermediate changes in MAP not significantly different from control. We conclude that combined H1 and H2 receptor blockade attenuates the cardiovascular effects associated with large doses of atracurium in the rabbit and that this combination of antagonist drugs might have similar effectiveness in humans.

Combined H1 and H2 receptor blockade attenuates the cardiovascular effects of high-dose atracurium for rapid sequence endotracheal intubation

Large doses of atracurium (1.5 mg/kg) (six times the ED95) can result in significant histamine release, resulting in systemic hypotension. The efficacy of histamine receptor blockade in attenuating atracurium induced hypotension was therefore studied. Four groups of seven patients each were studied: group I, control; group II, H1 blockade (1 mg/kg diphenhydramine); group III, H2 blockade (cimetidine 4 mg/kg); and group IV, H1 and H2 blockade (diphenhydramine 1 mg/kg and cimetidine 4 mg/kg). All patients were anesthetized with an intravenous narcotic-nitrous oxide technique and then given 1.5 mg/kg atracurium. In group I, mean arterial pressure (MAP) decreased 30 mm Hg after 2 minutes and remained 25 mm Hg below baseline at 3 minutes, a change significantly greater than that in group IV, in which MAP decreased 8 and 7 mm Hg, respectively. H1 receptor blockade was associated with no significant attenuation of changes in MAP. H2 receptor blockade alone was associated with significant decreases in MAP, possibly secondary to enhanced release of histamine via an antagonist effect on recently described H3 receptors. Plasma histamine levels increased significantly 2 minutes after atracurium administration and correlated with hemodynamic changes. It is concluded that combined H1 and H2 receptor blockade attenuates cardiovascular effects associated with large doses of atracurium in humans. Histamine-releasing agents may be contraindicated in patients subject to chronic H2 receptor blockade.

Surgical procedures among those greater than or equal to 90 years of age. A population-based study in Olmsted County, Minnesota, 1975-1985

Persons greater than or equal to 90 years of age represent a rapidly growing subset of the population, but little data exist on their utilization of the health care system. Population-based data capabilities of the Rochester/Olmsted County Epidemiology Project were used to study the performance of surgery among persons greater than or equal to 90 years of age for the 11-year period, 1975-1985. During this time, 224 residents of Olmsted County, Minnesota underwent 301 separate operations. The annual operation rate increased over the course of the study (trend test, p less than 0.001), reaching a plateau of 89.0 per 1000 person-years. This suggests a potential for nearly 91,000 operations annually in this age group based on 1987 U.S. Census estimates. Ninety-two per cent were discharged from the hospital alive, and 5-year survival was consistent with that expected (23% vs. 17%). Increased longevity of the general population, combined with increased performance of surgery in this rapidly growing segment of the population, may have significant implications for health care planning.

The effects of intraoperative blood salvage and induced hypotension on transfusion requirements during spinal surgical procedures

Spinal surgical procedures, such as placement of Harrington rods for correction of scoliosis, are associated with considerable perioperative blood loss and, hence, with the risks associated with homologous blood transfusions. To test the hypothesis that intraoperative autologous blood transfusions could decrease the amount of homologous blood needed in such operations, we conducted a two-part study: (1) a retrospective review of 142 patients in whom blood salvage was not used and (2) a prospective review of 28 patients who received autologous transfusions. Intraoperative autologous transfusion reduced the amount of homologous blood required by more than 50% (5.1 versus 2.0 units; P less than 0.001). The total amount of homologous blood required during the hospital stay was also significantly reduced by intraoperative autologous transfusion (6.0 versus 3.4 units; P less than 0.001). Induced hypotension in 81 of the 142 patients who did not receive autologous transfusions did not decrease the homologous blood transfusion requirements from those needed by the normotensive patients. We conclude that intraoperative autologous transfusion significantly reduces the need for homologous blood products in patients who undergo spinal surgical procedures. Induced hypotension, which did not affect transfusion requirements in our study, should be further evaluated in a blinded, prospective study.

Monitoring and analysis of oxygenation and ventilation during rigid bronchoscopic neodymium-YAG laser resection of airway tumors

Neodymium-YAG (yttrium-aluminum-garnet) laser resection of obstructing and inoperable tumors of the large airways is used as palliative therapy to improve the quality of survival in patients by alleviating airway obstruction. Rapid changes in oxygenation and ventilation can occur during these procedures. In a study of 14 patients, transcutaneous oxygen (PtcO2) and carbon dioxide (PtcCO2) monitors responded slowly to these changes and frequently provided misleading values. Pulse oximetry (SNO2) accurately reflected arterial oxygen saturation but did not indicate severe desaturation until arterial oxygen tension approached dangerously low values. Thus, we did not find PtcO2 or PtcCO2 monitoring to be clinically useful during neodymium-YAG laser resection of airway tumors through a rigid bronchoscope. SNO2 was clinically useful and accurate; however, a large decrement in oxygenation may occur before changes in oxygen saturation ensue and are detected.