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Biomedical subjects

M A Warner

Publications and source records attributed to M A Warner.

At least 55 records · Page 3Linked to original sources
PubMed1995

Color Doppler sonography of adnexal torsion.

The purpose of this study was to describe the color Doppler sonographic findings in adnexal torsion that distinguish viable from nonviable ovaries. We present the color Doppler sonographic features in 13 patients with surgically proved adnexal torsion that help determine whether or not the ovaries were viable or nonviable at the time of surgery. Eleven combined ovarian and tubal torsions and two isolated tubal torsions were studied. In 10 cases the ovaries were considered nonviable at the time of surgery and in three cases they were considered viable. Of the nonviable group, six showed absent arterial and venous flow centrally, but two had low velocity (< 5 cm/s) arterial flow peripherally in the region of the adnexal branch of the uterine artery or in the main ovarian artery, and two demonstrated absent or reversed diastolic arterial flow. None of the nonviable ovaries showed venous flow centrally. In contrast, all of the viable ovaries demonstrated venous flow centrally, and two had peripheral and central arterial flow. Although the CDS findings in adnexal torsion are variable, ovarian viability may be predicted if central venous flow is present.

Adolescent↗
PubMed1994

Quantification of occupational latex aeroallergens in a medical center.

To determine the quantity, variability, and mean aerodynamic diameter of latex aeroallergens in a large medical center, we collected air samples from work sites by using area and personal breathing zone air samplers, and we measured latex allergens by an inhibition assay with IgE antibodies from latex-sensitive individuals. Latex aeroallergen concentrations in 11 areas where powdered latex gloves were frequently used ranged from 13 to 208 ng/m3, and in areas where powdered latex gloves were never or seldom used, concentrations ranged from 0.3 to 1.8 ng/m3. Installation and use of a laminar flow glove changing station in one work area did not reduce latex aeroallergen levels. Large quantities of allergen were recovered from used laboratory coats and anesthesia scrub suits and from laboratory surfaces. Latex allergen concentrations in personal breathing zone samplers worn by health care workers in areas where powdered gloves were frequently used ranged from 8 to 974 ng/m3. Exposure likely occurs when gloves are changed and as a result of resuspension from reservoirs of powder in the room and clothing. Latex allergens were found in all particle sizes but were predominant in particles greater than 7 microns in mass median aerodynamic diameter. Results of electrophoretic immunoblotting showed that the aeroallergens are primarily the higher molecular mass components of the latex glove proteins. Measures to control exposure can be monitored by both area and personal air sampling with this immunochemical approach. Use of gloves with low allergen content or powder-free gloves appears to be more effective than use of a laminar flow glove changing station in reducing aeroallergen levels.

Academic Medical Centers↗
PubMed1994

Extractable latex allergens and proteins in disposable medical gloves and other rubber products.

BACKGROUND: IgE-mediated sensitization to rubber proteins is being reported with increasing frequency in health care workers. To explore the relative importance of various sources of allergen exposure, we measured the total rubber allergen and protein levels in extracts of disposable rubber gloves and compared the allergen levels with those in extracts of other medical and consumer rubber products. METHODS: Rubber allergens were measured by inhibition immunoassay with a rubber glove extract as the solid-phase allergen and pooled plasma from five rubber-sensitized health care workers as the IgE antibody source. Proteins were measured by Ninhydrin assay. RESULTS: Among 71 lots of gloves tested, the extractable allergen and protein levels were significantly correlated and were appreciably higher in powdered gloves than in powder-free gloves. Allergen levels varied 3000-fold among gloves from different manufacturers and were higher in examination gloves than in surgical or chemotherapy gloves. Measurable allergen was found in 11 of 24 lots of "hypoallergenic" gloves tested. Allergen levels in toy balloons were comparable to those in powdered gloves; much lower allergen levels were measured in condoms and anesthesia rebreathing bags. CONCLUSIONS: The allergen content of disposable rubber gloves varies widely and is higher in powdered gloves than in powder-free gloves and higher in examination gloves than in surgical gloves. Hypoallergenic gloves may contain substantial amounts of IgE-binding proteins. Gloves and toy balloons appear to be more important sources of rubber allergens than the other rubber products tested.

Allergens↗
PubMed1994

Malignant pheochromocytoma masquerading as acute pancreatitis--a rare but potentially lethal occurrence.

Pheochromocytoma mimicking acute pancreatitis as its initial clinical manifestation is a known, albeit rare, phenomenon. Herein we describe a patient with this occurrence. A striking feature was pronounced hyperamylasemia, almost exclusively of the S-type. Our theory is that the pheochromocytoma caused a catecholamine-induced cardiomyopathy, which contributed to failure of the left ventricle; pulmonary edema and release of S-type amylase from hypoxic lung tissue occurred subsequently.

Acute Disease↗
PubMed1994

Lower-extremity motor neuropathy associated with surgery performed on patients in a lithotomy position.

BACKGROUND: Motor neuropathy of a lower extremity is well-recognized as a potential complication of procedures performed on patients in a lithotomy position. Most of this awareness is based on anecdotal reports, however, and the incidence and risk factors for this complication have not been reported. METHODS: We retrospectively reviewed the perioperative courses of 198,461 consecutive patients who underwent 1 of 56 surgical procedures historically performed on patients in a lithotomy position at the Mayo Clinic, Rochester, Minnesota, from 1957 to 1991 inclusive. The medical diagnoses of patients who had procedures in a lithotomy position were scanned for 26 diagnoses associated with neuropathy. Persistent neuropathy of the lower extremity was defined as a motor deficit of at least 3 months' duration. Risk factors anecdotally associated with persistent neuropathy were analyzed by comparing identified cases of neuropathy to controls in a 1:3 case-control study. RESULTS: Persistent neuropathies after procedures performed on patients in a lithotomy position were identified in 55 cases for a rate of 1 per 3,608. Multivariate risk factors for development of a persistent neuropathy of a lower extremity included duration in lithotomy of 4 h or longer, a body mass index (kilograms per squared meter) of 20 or less, and a history of smoking within 30 days of the procedure. Regional anesthetic techniques were not found to be associated with an increased risk of neuropathy. Of the 53 patients who lived at least 1 yr after their procedure, 24 (45%) required either prosthetic or ambulatory support for persistent foot drop or leg weakness. CONCLUSIONS: These data suggest that prolonged duration in lithotomy and patient risk factors, including very thin body habitus and smoking in the preoperative period, are associated with the development of a lower-extremity neuropathy after procedures performed on patients in a lithotomy position. A reduction of time in the lithotomy position may be particularly worthwhile for patients with these risk factors.

Adolescent↗
PubMed1994

Alzheimer's disease and cumulative exposure to anesthesia: a case-control study.

OBJECTIVE: To evaluate prior exposure to general anesthesia as a potential risk factor for Alzheimer's disease (AD). DESIGN: A retrospective, population-based, case-control study. SETTING: The Rochester Epidemiology Resource. PATIENTS: Cases were all incident cases of AD from 1975 to 1984 who resided for 40 years or more in Olmsted County prior to the onset of their dementia (n = 252). One age- and gender-matched control for each case was selected from all registrations for care at Mayo Clinic during the year of onset in the incident case. The case and control groups each had 252 individuals. Of these, 208 cases and 199 controls had at least one exposure to general anesthesia prior to the year of onset of dementia in the matched AD patient. MEASUREMENTS: The cumulative duration of anesthesia and the total number of general anesthetic exposures prior to the age of onset of dementia and the corresponding year in each matched control were ascertained. RESULTS: There was no significant difference in mean cumulative exposure (in minutes) to general anesthesia (patients vs controls: 188.4 vs 170.5 minutes, ns). Neither exposure to six or more episodes of general anesthesia (OR = 1.44; 95% CI: 0.77-2.71) nor cumulative exposure to 600 minutes or more of general anesthesia (OR = 1.63; 95% CI: 0.53-5.04) were associated with a significantly increased risk of AD. CONCLUSION: It is unlikely that multiple exposures to general anesthesia increase the risk of AD.

Aged↗
PubMed1994

Prior blood transfusions and Alzheimer's disease.

We performed a population-based, case-control study to evaluate prior blood transfusion as a potential risk factor for Alzheimer's disease (AD). All cases were incident cases of AD from 1975 to 1984 with residence for 40 years or more in Olmsted County, Minnesota, prior to their onset of dementia (N = 252). There was one age- and gender-matched control for each case. We ascertained the number of blood transfusions prior to the age of onset of dementia and the corresponding year in each control. Sixty-five cases and 55 controls had at least one prior blood transfusion. We did not find a significantly increased risk of AD for the events of at least one, three, or six blood transfusions.

Adult↗
PubMed1994

Early and midlife exposure to anesthesia and age of onset of Alzheimer's disease.

Patients with Alzheimer's disease (AD) who have a late onset of dementia may represent a subgroup of AD that has a unique multifactorial/genetic profile. It was hypothesized in the present study that if external factors interact with a biological or genetic susceptibility in at least some subsets of patients with AD, these factors may accelerate the manifestation of the disease. The cumulative exposure to different types of general and major regional anesthetics prior to the onset of dementia was calculated in a population-based study of incident cases of AD residing in Rochester, MN, for more than 40 years preceding the onset of dementia (N = 252). Correlational analysis revealed that age of onset was inversely related to cumulative exposure to general and spinal anesthesia before the age of 50, whereas there was no, or an expected positive, correlation for anesthetic exposure after 50 years. These findings may suggest that the manifestation of dementia in AD patients may be related to exposure to external factors at an earlier age.

Age Factors↗
PubMed1994

Ulnar neuropathy. Incidence, outcome, and risk factors in sedated or anesthetized patients.

BACKGROUND: Ulnar neuropathy is well-recognized as a potential complication of procedures performed on anesthetized patients. However, reported outcomes and risk factors for this problem are based on small series and anecdotes. METHODS: We retrospectively reviewed the perioperative courses of 1,129,692 consecutive patients who underwent diagnostic and noncardiac surgical procedures with concurrent anesthetic management at the Mayo Clinic from 1957 through 1991 (inclusive). The medical diagnoses of patients who had these procedures were scanned for 26 diagnoses associated with neuropathy. Persistent neuropathy of an ulnar nerve was defined as a sensory or motor deficit of greater than 3 months' duration. Risk factors anecdotally associated with persistent neuropathy were analyzed by comparing patients with an ulnar neuropathy with control subjects in a 1:3 case-control study. RESULTS: Persistent ulnar neuropathies were identified in 414 patients, a rate of 1 per 2,729 patients. Of these, 38 (9%) patients had bilateral neuropathies. Approximately equal numbers of the neuropathies included sensory loss only or mixed sensory and motor loss. Initial symptoms form most neuropathies were noted more than 24 h after the procedure. Factors associated with persistent ulnar neuropathy included male gender and a duration of hospitalization of more than 14 days (P < 0.01). Neuropathy was more likely to develop in very thin and obese patients than in patients with average body habitus. Neither the type of anesthetic technique nor the patient position was found to be associated with this neuropathy. Of the 382 patients who survived the 1st postoperative yr, 53% regained complete motor function and sensation and were asymptomatic. Of those with neuropathies persisting for more than 1 yr, most had moderate or greater disability from pain or weakness. CONCLUSIONS: These data suggest that perioperative ulnar neuropathies are associated with factors other than general anesthesia and intraoperative positioning. Men at the extremes of body habitus who have prolonged hospitalizations are particularly susceptible to development of ulnar neuropathies.

Adult↗
PubMed1993

Clinical significance of pulmonary aspiration during the perioperative period.

BACKGROUND: Pulmonary aspiration of gastric contents during the perioperative period may be associated with postoperative mortality or pulmonary morbidity. Recent determination of the incidence of perioperative pulmonary aspiration and evaluation of factors related to clinical outcomes is lacking. METHODS: We retrospectively reviewed the perioperative courses of 172,334 consecutive patients 18 yr of age or older who underwent 215,488 general anesthetics for procedures performed in all surgical specialties from July 1985 to June 1991. Pulmonary aspiration was defined as either the presence of bilious secretions or particulate matter in the tracheobronchial tree or, in patients who did not have their tracheobronchial airways directly examined after regurgitation, the presence of an infiltrate on postoperative chest roentgenogram that was not identified by preoperative roentgenogram or physical examination. RESULTS: Pulmonary aspiration occurred in 67 patients (1:3,216 anesthetics). Fifteen aspirations occurred in 13,427 (1:895) anesthetics of patients undergoing emergency surgery, and 52 occurred in 202,061 (1:3,886) anesthetics of patients undergoing elective surgery (P < .001). Of the 66 patients who survived their surgery, 42 (64%) did not develop a cough or wheeze, a decrease in arterial hemoglobin oxygen saturation while breathing room air > 10% less than the preoperative value, or radiographic abnormalities within 2 h of aspiration. These 42 patients had no respiratory sequelae. Of the 24 patients who had one or more of these findings, 13 required mechanical ventilatory support for more than 6 h. Three of the six patients whose lungs required mechanical ventilation for more than 24 h died from pulmonary insufficiency (overall mortality = 1:71,829 anesthetics). CONCLUSIONS: This study suggests that patients with clinically apparent aspiration who do not develop symptoms within 2 h are unlikely to have respiratory sequelae.

Adult↗
PubMed1992

Sympathetic modulation of blood flow and O2 uptake in rhythmically contracting human forearm muscles.

This study tested the effects of sympathetically mediated changes in blood flow to active muscles on muscle O2 uptake (VO2) in humans. Four minutes of graded (15-80% of maximum voluntary contraction, MVC) rhythmic handgrip exercise were performed. Forearm blood flow (FBF) (plethysmography) and deep vein O2 saturation were measured each minute. Forearm O2 uptake was calculated using the Fick principle. In protocol 1, exercise was performed while supine and again while upright to augment sympathetic outflow to the active muscles. Standing reduced FBF at rest from 3.6 to 2.2 ml.100 ml-1.min-1 (P < 0.05). During light exercise (15-40% MVC) FBF was unaffected by body position. Standing reduced FBF (P < 0.05) from 36.0 to 25.2 ml.100 ml-1.min-1 and forearm VO2 from 38.2 to 28.1 ml.kg-1.min-1 during the final work load. In protocol 2, exercise was performed while supine before and after local anesthetic block of the sympathetic nerves to the forearm. Sympathetic block increased FBF at rest from 3.1 to 8.9 ml.100 ml-1.min-1 (P < 0.05), and FBF was higher during all work loads At 70-80% of MVC sympathetic block increased FBF from 35.4 to 50.7 ml.100 ml-1.min-1 (P < 0.05), and forearm VO2 from 45.5 to 54.2 ml.kg-1.min-1 (P < 0.05). These results suggest that in humans sympathetic nerves modulate blood flow to active muscles during light and heavy rhythmic exercise and that this restraint of flow can limit O2 uptake in muscles performing heavy rhythmic exercise.

Adolescent↗
PubMed1991

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.

Aged↗
PubMed1991

Preoperative laboratory screening in healthy Mayo patients: cost-effective elimination of tests and unchanged outcomes.

We reviewed the results of preoperative screening laboratory tests in asymptomatic healthy patients who underwent elective surgical procedures at our institution in 1988. Substantially abnormal results were found in 160 of 3,782 patients. All such abnormalities involved five tests: aspartate aminotransferase, glucose, potassium, platelet count, and hemoglobin. Thirty of the abnormal test results were predictable on the basis of the history or physical examination. The abnormal test result prompted further assessment in 47 patients. No surgical procedure was delayed, and no association was noted between adverse outcome and any preoperative laboratory abnormality. Because of our findings in this analysis and similar studies on specific tests from other institutions, we no longer require preoperative laboratory screening tests for healthy patients.

Adult↗
PubMed1991

Regionally selective effects of NMDA receptor antagonists against ischemic brain damage in the gerbil.

This study compared the ability of three N-methyl-D-aspartate (NMDA) receptor antagonists to prevent neuronal degeneration in an animal model of global cerebral ischemia. The model employed is characterized by damage to the striatum, hippocampus, and neocortex. Antagonists were administered to gerbils either before or after a 5-min bilateral carotid occlusion. The intraischemic rectal temperature was either maintained at 36-37 degrees C or allowed to fall passively to 28-32 degrees C. Antagonists and doses tested were 1 and 10 mg/kg of MK-801 (pre- or postischemia), 30 mg/kg of CGS 19755 preischemia, four 25 mg/kg doses of CGS 19755 administered between 0.5 and 6.5 h postischemia, and 40 mg/kg of MDL 27,266 (pre- or postischemia). All three NMDA receptor antagonists exhibited some degree of neuroprotective activity when the carotid occlusion was performed under normothermic conditions. Most of the treatments with antagonist markedly reduced striatal damage. CA1 hippocampal and neocortical pyramidal cells were spared by only three of the treatments, however, and the extent of neuroprotection varied widely from case to case. Toxic doses of antagonist were required to protect CA1 pyramidal cells from ischemic damage. Ischemic damage to hippocampal areas CA2-CA3a and CA4 appeared to be resistant to all of these treatments. Most CA1 pyramidal cells that were protected from degeneration by an NMDA receptor antagonist were histologically abnormal. The neuroprotective effects of MK-801 and intraischemic hypothermia appeared to be additive. MK-801 (10 mg/kg) consistently reduced the postischemic brain temperature, but only the magnitude of hypothermia produced soon after reperfusion correlated with its neuroprotective action. These results suggest that NMDA receptor antagonists are relatively poor neuroprotective agents against a moderately severe ischemic insult.

Animals↗
PubMed1990

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.

Academic Medical Centers↗
PubMed1990

Transfusion risks.

Hepatitis remains the most serious transfusion risk, in terms of incidence and severity. Transfusion-associated AIDS, hemolytic reactions, TRALI, and anaphylaxis are severe problems that occur relatively rarely, while febrile reactions and mild allergic reactions are common but not serious. The key to avoiding all these complications is autotransfusion (see the article "Autologous Transfusion" in this issue). Although intraoperative scavenging became available in many centers in the United States in the 1980s, it is hoped that pre-deposit autotransfusion will also become widely utilized in the next decade.

Acquired Immunodeficiency Syndrome↗