Search PubMed⌕ Search

Biomedical subjects

R A Thisted

Publications and source records attributed to R A Thisted.

At least 37 records · Page 2Linked to original sources
PubMed1994

Mucosal allergy in the absence of systemic allergy in nasal polyposis and rhinitis: a meta-analysis.

To better determine the role of allergy in rhinitis and nasal polyposis, we assessed the prevalence of nasal mucosal allergy in the absence of systemic allergy. After a thorough literature search we compiled and analyzed data from nine studies (287 patients) that tested for specific immunoglobulin E both intranasally and systemically. When meta-analysis was applied to the different populations, 19% of those who demonstrated specific immunoglobulin E manifested nasal mucosal allergy but no systemic allergy. We suggest that there is an important segment of rhinitis and nasal polyp patients who have nasal mucosal allergy.

Humans↗
PubMed1994

Predictive and diagnostic tests of renal failure: a review.

Postoperative acute renal insufficiency is a discouraging complication with a mortality rate that remains persistently high, despite improved techniques of dialysis and advances in the perioperative management of hemodynamic, metabolic, and infective complications. A complete understanding of the role of renal hemodynamics in the pathophysiology of acute renal failure still has not emerged. Serial determination of creatinine clearance is currently the most sensitive test for predicting the onset of perioperative renal dysfunction; however, the test is not practical for measuring renal function under operating room conditions. Furthermore, testing creatinine clearance is time-consuming, labor intensive, and may cause significant delay in identifying the onset of renal dysfunction. That early therapy modifies the prognosis of renal dysfunction remains an untested hypothesis until a measurement that predicts renal outcome is found that is sensitive, specific, and easily obtainable. The ability to measure intrarenal blood flow distribution may offer promise for improving our predictive and diagnostic abilities to assess perioperative acute renal failure. Methodologic constraints, however, limit the practicality of this measurement in the perioperative setting at this time. Instead, we rely on indirect variables that do not bear a reliable relationship to glomerular filtration rate and renal function.

Acute Kidney Injury↗
PubMed1994

Association of preoperative risk factors with postoperative acute renal failure.

We performed a systematic review of 28 studies that examined preoperative risk factors for postoperative renal failure. Included in the studies were 10,865 patients who underwent either vascular, cardiac, general, or biliary surgery. No two studies used the same criteria for acute renal failure. Variability in definitions of renal failure, lack of consistent criteria for establishing risk factors, and nonuniformity in the statistical methods employed result in a literature that is not adequate to support a comprehensive quantitative review. Of the 30 variables considered in the studies, preoperative renal risk factors, such as increased serum creatinine, increased blood urea nitrogen, and preoperative renal dysfunction were repeatedly found to predict postoperative renal dysfunction. The literature provides little quantitative information concerning the degree of risk associated with other factors. Cardiac risk factors, such as left ventricular dysfunction, were reported to be predictive of postoperative renal failure more consistently than was advanced age.

Acute Kidney Injury↗
PubMed1994

Relative effectiveness of four preoperative tests for predicting adverse cardiac outcomes after vascular surgery: a meta-analysis.

Various noninvasive tests have been proposed to stratify perioperative cardiovascular risk, including dipyridamole thallium scintigraphy (DTS), ejection fraction estimation by radionuclide ventriculography (RNV), ischemia monitoring by ambulatory electrocardiography (AECG), and dobutamine stress echocardiography (DSE). Which of these tests is most effective for predicting adverse perioperative cardiac outcome? To answer this question, and also to stimulate future studies, we evaluated 56 studies examining one or more of the four tests. We conducted meta-analysis on 20 studies that met the inclusion criteria. Outcome measures evaluated were cardiac death or myocardial infarction occurring during hospital stay or within 1 mo after surgery. Relative risk (RR), which is the probability of adverse cardiac outcome when the test is positive divided by the probability of adverse outcome when the test is negative, was used to combine evidence from different studies. An empirical Bayes procedure with a normal-normal hierarchic model was then used to obtain a meta-analytic confidence interval for the overall median of the relative risks. The between-study variance was estimated using the method of moments approach described by DerSimonian and Laird (Controlled Clin Trials 1986;7:177-88). Combined (median) RR [95% confidence interval (CI)] and the number of studies included in our meta-analysis for different evaluative tests were as follows: DTS 4.6 (2.1-10.4) (n = 6); RNV 3.7 (1.6-8.3) (n = 5); AECG 2.7 (1.4-5.1) (n = 6), and DSE 6.2 (1.7-22.8) (n = 3). We conclude that while DTS, RNV, AECG, and DSE are effective (the 95% CIs are greater than 1.0) in predicting the cardiac outcome after vascular surgery, the data are not definitive in determining the optimal test (95% CIs for RR overlap). Future studies should include DSE, as this test shows great promise for predicting adverse cardiac events after vascular surgery.

Coronary Angiography↗
PubMed1993

The interaction between alcohol and the residual effects of thiopental anesthesia.

BACKGROUND: During ambulatory surgery, barbiturates, such as thiopental, may impair psychomotor performance several hours after administration. It was hypothesized that if patients drink alcohol 4 h after thiopental injection, the increase in psychomotor impairment would be greater than that seen after alcohol ingestion alone. METHODS: Twelve healthy men volunteered to participate in a double-blind, placebo-controlled, crossover study with a Latin square design. On each testing day, the subjects received intravenous injections of either 5 mg/kg of 2.5% thiopental or an equal volume of saline for 30 s. Four hours after injection, the subjects consumed a beverage with or without 0.7 g/kg alcohol. Psychomotor performance and mood were assessed at five times: prior to injection, at 1 h and 3 h after injection, and at 1 h and 3 h after consumption of beverage. RESULTS: Both thiopental and alcohol had strong independent effects on the dependent measures in this study. In addition, body sway, one of the nine psychomotor tests used to assess impairment, was greater after thiopental and alcohol than after alcohol alone. Of eleven adjectives used to assess mood, lightheadedness was cited most frequently after a combination of thiopental and alcohol than after each alone. CONCLUSIONS: Based on our tests of performance and mood, an interaction between thiopental and alcohol is evident; in addition, the interaction between both drugs may exert deleterious effects on higher levels of central nervous system integration.

Adult↗
PubMed1993

The initial clinical experience of 1819 physicians in maintaining anesthesia with propofol: characteristics associated with prolonged time to awakening.

In October 1989, propofol underwent Phase IV Food and Drug Administration testing that involved 25,981 patients, 1722 institutions, and 1819 anesthesiologists. Participants were 18-80 yr of age and ASA physical status I-III; they could not have a continuing pregnancy or prior adverse anesthetic experience. Anesthesiologists completed detailed forms to describe their use of propofol in this three-step study: propofol for induction only (Step 1), for induction and then maintenance by intermittent bolus injection (Step 2), or for continuous infusion (Step 3). In early 1992, our group of anesthesiologists and epidemiologists analyzed the resulting data base. We evaluated data from 14,882 patients (8095 given bolus injections and 6787 given continuous infusion) to determine factors predicting prolonged time (> 15 min after cessation of all anesthesia) to awakening, one measure of recovery from anesthesia. The incidence of prolonged awakening was 6.8% (1016 patients); the median and mean (+/- SD) times to awakening were, respectively, 5 min and 7.2 +/- 7.3 min. The following variables were associated (P < 0.05) with prolonged awakening from propofol maintenance anesthesia: a total dose of propofol > 8 mg/kg, male gender, endotracheal intubation, age > 65 yr, abdominal surgery, continuous infusion of propofol, and concomitant use of isoflurane or benzodiazepines. These results support the clinical impression that recovery from propofol anesthesia is remarkably rapid; although the vast majority of physicians participating in this study were using propofol for maintenance for the first time, only 6.8% of patients had awakening times exceeding 15 min.

Adolescent↗
PubMed1993

Effects on recovery when isoflurane is used to supplement propofol-nitrous oxide anesthesia.

During propofol-nitrous oxide (N2O) anesthesia, volatile anesthetics are frequently administered to treat signs of inadequate anesthesia and to decrease the possibility of intraoperative awareness. Because the clinical effects of this combination have not been examined rigorously, we used data from the 1989-90 Phase IV clinical trial with propofol to evaluate recovery from propofol-N2O anesthesia with and without supplementation with isoflurane. In this study involving 15,806 patients at 1722 institutions, propofol was administered for induction and maintenance of anesthesia with N2O for procedures lasting less than 60 min. At the discretion of the anesthesiologist, volatile anesthetics were administered as needed during maintenance of anesthesia (the incidence of use of inhaled anesthetics was 14.7% for isoflurane, 2.2% for enflurane, and 0.2% for halothane). Other intraoperative medications included opioid analgesics, muscle relaxants, and anticholinergic drugs. The present study concerns the subset of 7796 patients given propofol-N2O maintenance anesthesia (intermittent bolus or continuous infusion) with or without isoflurane supplementation for procedures lasting less than 60 min. Isoflurane was used more frequently for procedures lasting 30-60 min than for those less than 30 min. Nevertheless, the maintenance dose of propofol was significantly (P < 0.05) less with isoflurane (178 vs 235 mg). Adjunctive use of isoflurane prolonged the time to awakening and to becoming oriented, but discharge times were similar for the two groups. The incidence of postoperative nausea, vomiting, recall, and excitement did not differ between the two groups. We conclude that the addition of isoflurane to a propofol-N2O anesthetic does not alter recovery from anesthesia.

Adolescent↗
PubMed1993

Hemodynamic effects of propofol: data from over 25,000 patients.

To investigate clinically important hypotension and bradycardia after induction of anesthesia with propofol, we analyzed data from a Phase IV stepwise study involving 25,981 patients, 1722 institutions, and 1819 anesthesiologists. In Step 1, propofol was used for induction only. In Step 2, propofol was used for induction and then maintenance by intermittent injection. In Step 3, an induction dose was followed by a maintenance infusion. Participants were to be 18-80 yr of age and ASA physical status I-III; they could not have a continuing pregnancy or prior adverse anesthetic experience. Detailed data on demographic, perioperative, and outcome variables were recorded on data collection forms. The overall incidence of hypotension (systolic blood pressure < 90 mm Hg) was 15.7%; 77% of the episodes were recorded within 10 min of induction of anesthesia with propofol. Bradycardia (heart rate < 50 beats/min) occurred in 4.8% of patients, with 42% of the episodes in the first 10 min. Only 1.3% of patients had both hypotension and bradycardia. The incidence of hypotension was significantly higher for the elderly, females, Caucasians, those undergoing abdominal and integumentary procedures, and those given propofol with opioids, benzodiazepines, or propranolol. Bradycardia was significantly more common when propofol was combined with opioids or chronically taken beta-adrenergic receptor-blocking drugs. Bradycardia and hypotension were not commonly associated. Giving this new drug by protocol, even inexperienced anesthesiologists incurred few adverse hemodynamic changes. Hemodynamic changes were transient and rarely (< 0.2%) required drug therapy. Cardiovascular changes and drug interactions were predictable and manageable based on knowledge of the pharmacology of propofol.

Adolescent↗
PubMed1993

Adverse events in a multicenter phase IV study of propofol: evaluation by anesthesiologists and postanesthesia care unit nurses.

Phase II and III studies are tightly controlled trials investigating adverse effects before government approval of a new drug. However, because postapproval Phase IV studies involve a much larger and more complex population, the true nature of adverse effects can be seen. We analyzed Phase IV data for the new drug propofol with regard to the incidence of adverse events, and evaluations of such events by anesthesiologists versus postanesthesia care unit (PACU) nurses. Data pertained to 25,981 patients, 1722 institutions, and 1819 anesthesiologists giving propofol in three anesthetic regimens. Inclusion criteria were liberal: age, 18-80 yr; ASA physical status I-III; no continuing pregnancy; and no prior adverse anesthetic experience. Anesthesiologists and PACU nurses used data collection forms to record demographic, perioperative, and outcome variables; to evaluate recovery (excellent, good, or poor); and to describe adverse events. Adverse events were reported for 2813 patients (10.8%); the most common events were pain on injection (5.2%), hypotension (1.1%), nausea/vomiting (1.9%), and excitement (1.3%). The incidences of pain on injection and nausea/vomiting were approximately one-half and one-fifth, respectively, the values reported in earlier studies. Six hundred thirty-three patients (2.4%) had a "poor" recovery according to one or both of the evaluators (the anesthesiologist or PACU nurse). The PACU nurse was more influenced by nausea, vomiting, or postoperative pain; and the anesthesiologist was more influenced by postoperative confusion or delayed emergence from anesthesia. For only 0.6% of patients did both evaluators rate recovery as poor. Anesthesiologists gave more weight to intraoperative adverse events, and nurses to postoperative events.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

How do anesthesiologists select patients when introducing a new drug into practice?

As part of the marketing strategy for the anesthetic drug propofol (Diprivan), Stuart Pharmaceuticals began a Phase IV postmarketing study soon after the drug received Food and Drug Administration approval in 1989. We used data from this study to test the hypothesis that anesthesiologists would initially use propofol for young, relatively healthy patients and then, with experience, for older, sicker patients. The Phase IV study involved 1722 institutions, 1819 anesthesiologists, and 25,981 patients. The study incorporated three sequential steps, each to be tested in five patients. In Step 1, propofol was used for induction only; in Step 2, for induction and maintenance of anesthesia by intermittent injection; and, in Step 3, for induction and maintenance by continuous infusion. Inclusion criteria were age 18-80 yr and ASA physical status I-III. Exclusion criteria were continuing pregnancy and a previous adverse anesthetic experience. Physicians used standardized data collection forms to voluntarily compile detailed demographic, perioperative, and outcome variables for patients. Data were then evaluated by an independent, multicenter team of seven anesthesiologists and three epidemiologists to determine whether the first two patients selected to participate in each step (Patients 1 and 2, 6 and 7, and 11 and 12) were less sick, younger, or undergoing less invasive or shorter procedures than patients enrolled later in the same steps (Patients 4 and 5, 9 and 10, and 14 and 15). Physicians gave propofol first to patients with fewer concurrent diseases than are found in the general population (10% were hypertensive versus 16%; 3% were diabetic versus 10%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Phase IV study of propofol: validation of the data set.

In 1989-1990, Stuart Pharmaceuticals conducted a Phase IV study of propofol on over 26,000 patients, later making the large data base available to a team of epidemiologists and anesthesiologists for analysis. We now describe the process of verifying the data to provide a sound basis for further analyses. Original data were collected by 1819 physicians at 1761 hospitals. In that study, anesthesia was induced by bolus injection of propofol and was maintained by inhaled drug and N2O-O2 (Step 1), or by propofol (either intermittent bolus injection [Step 2] or continuous infusion [Step 3]) and N2O-O2. Forty-six recorded variables described history, physical examination, course and quality of anesthesia and recovery, and adverse events. Data were scrutinized for inaccuracy or bias regarding adverse events, completeness of data, data entry, and violations of the study protocol. The initial data set pertained to 26,841 patients (10,698, Step 1; 8886, Step 2; and 7257, Step 3). Because we excluded data if 25% of the items were missing from the data set, 3.2% of the case reports were eliminated: the final data set used for subsequent analyses contained 25,981 patients (10,184, Step 1; 8672, Step 2; and 7125, Step 3). Inaccuracy of data entry was not excessive, and violations of study protocol were less frequent than in similar studies. The nature and frequency of adverse events were similar to those reported in Phase II and III clinical trials of propofol. Analysis showed that missing data occurred randomly and did not introduce obvious bias. We conclude that the data set was valid and most likely represents perioperative events occurring in similar patients; that Phase IV studies can be valuable because of the range of patients studied and the ability to detect even rare events; and that future Phase IV studies could be improved by more efficient design of data collection forms for both hypotheses to be tested and the entry of data onto forms.

Adolescent↗
PubMed1993

The role of pharmacoepidemiology research in postmarketing surveillance and anesthesia practice/critical care medicine.

Despite tremendous efforts to ensure the safety and effectiveness of newly marketed medications, a number of these have had significant problems after introduction of the drug to the market. Such problems highlight the practical limitations of clinical trials performed to obtain FDA approval for marketing. Pharmacoepidemiology research methodologies provide a powerful mechanism for exploring the determinants of drug safety and effectiveness in broad-based populations and can serve as a scientific foundation for outcome research. Using these methodologies, largescale postmarketing surveillance studies similar to the type described in the accompanying articles would constitute an important way of confirming and identifying the determinants of drug safety and effectiveness in large, diverse patient populations.

Anesthesia↗
PubMed1992

Sleep and psychiatric disorders. A meta-analysis.

We reviewed the literature on sleep in psychiatric disorders and evaluated the data by meta-analysis, a statistical method designed to combine data from different studies. A total of 177 studies with data from 7151 patients and controls were reviewed. Most psychiatric groups showed significantly reduced sleep efficiency and total sleep time, accounted for by decrements in non-rapid eye movement sleep. Rapid eye movement sleep time was relatively preserved in all groups, and percentage of rapid eye movement sleep was increased in affective disorders. Reduction in rapid eye movement sleep latency was seen in affective disorders but occurred in other categories as well. Although no single sleep variable appeared to have absolute specificity for any particular psychiatric disorder, patterns of sleep disturbances associated with categories of psychiatric illnesses were observed. Overall, findings for patients with affective disorders differed most frequently and significantly from those for normal controls.

Adult↗
PubMed1992

Thromboelastogram fails to predict postoperative hemorrhage in cardiac patients.

To determine the clinical usefulness of the thromboelastogram in the prediction of postoperative hemorrhage in cardiac patients, we related the results of routine coagulation tests (RCTs) and thromboelastography with the amount of chest tube drainage postoperatively in 101 patients requiring cardiopulmonary bypass. Our data indicated that there was no correlation between RCT results and thromboelastographic variables. No single variable of RCTs and thromboelastography correlated well with the amount of chest tube drainage postoperatively. Before the onset of cardiopulmonary bypass, the most frequent abnormalities detected by thromboelastograms were fibrinolysis and hypocoagulability resulting from factor deficiency. Hypercoagulability detected by thromboelastograms occurred in 13% of patients after cardiopulmonary bypass and usually was not detected by RCTs. The incidence of false-negative thromboelastograms and RCT results in patients who had excessive hemorrhage of unknown cause was 46% and 52%, respectively. The incidence of fibrinolysis as detected by thromboelastograms was similar before and after bypass, but only 2 of the 18 patients with fibrinolysis had excessive hemorrhage postoperatively. Our results indicate that neither RCTs nor thromboelastography predicts the likelihood of excessive hemorrhage in patients after cardiopulmonary bypass. The thromboelastographic results should be interpreted cautiously because of the high rate of unreliable results.

Blood Coagulation Tests↗
PubMed1992

Central temperature changes are poorly perceived during epidural anesthesia.

Hypothermia and shivering are common during epidural anesthesia for cesarean delivery but are not always accompanied by a sensation of coldness. To test the hypothesis that central temperature changes are not perceived during epidural anesthesia, we measured central and skin temperatures and thermal perception in 30 patients undergoing cesarean delivery with epidural anesthesia. Central temperature decreased 1.0 +/- 0.6 degrees C from control values during anesthesia and surgery, but thermal perception scores did not reflect central temperatures (P = 0.56) or changes in central temperature (P = 0.63). A feeling of warmth was significantly correlated with increased mean skin temperature (P = 0.02) and increased upper body skin temperature (P = 0.03). We conclude that central temperature is poorly perceived and is less important than skin temperature in determining thermal perception during high levels of epidural anesthesia.

Adult↗
PubMed1992

Can patients use an automated questionnaire to define their current health status?

Patient management decisions rarely incorporate standardized health status assessments, since accurate and reliable measures are difficult and expensive to obtain. In prior research with various methods for obtaining health data from patients, it was found that physicians' acceptance of a method was improved if it provided an individualized printout. It was also determined that patients will readily complete a health status questionnaire on a computer when the computer does not look like a computer. Patients' acceptance was greatest when they were presented with a single line of large, pressure-sensitive buttons with which they could respond to questions about their health histories. Using such an instrument, the HealthQuiz, the current study found the same discrepancy rate (3%) between patients' responses to health questions presented on HealthQuiz and during interview as between their responses to questions asked during two separate interviews. Further, to ascertain health status, rules determined by an expert panel were applied to patients' responses to health questions presented on the HealthQuiz screen. It was found that the numerical health status derived from answers to the automated presentation of questions was similar to numerical health status derived by a physician after a patient-physician interview.

Aged↗
PubMed1992

Risk of human immunodeficiency virus in surgeons, anesthesiologists, and medical students.

We postulated that three factors determined the occupational risk of infection from the human immunodeficiency virus (HIV) for surgeons, anesthesiologists, and medical students: first, the risk of needlestick exposure per year (range for surgeons 3.8-6.2, weighted average 4.2; range for anesthesiologists 0.86-2.5, weighted average 1.3; range for third-year medical students 0-5, best estimate 5); second, the risk of seroconversion from a needlestick exposure (0.42%-0.50%); and third, prevalence of HIV in the population served (0.32%-23.6%, depending on geographic location). Thus, the calculated range for occupational risk of HIV infection for a surgeon over a 30-yr period (assuming no change in HIV prevalence or benefit from protective measures) was 0.17%-13.9%; for an anesthesiologist, 0.05%-4.50%. The corresponding range of occupational risk for a medical student during the third year was 0.007%-0.59%. The range of risk is large because the variation in prevalence of HIV infection from one area to another is great. The authors validated the methodology first by using an equation, with estimates from the literature for factors in the equation, to calculate the risk of infection for hepatitis B and then by comparing the results with known rates of infection in the prevaccine era. Calculated occupational risk of hepatitis B infection for anesthesiologists was in the lower range of actual prevalence of infection (calculated range 2.32%-20.6%; known range 6%-26%). Calculated risk versus prevalence for surgeons was fairly close (7.31%-53.4% versus 24.4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesiology↗