Biomedical subjects
R M Elenbaas
Publications and source records attributed to R M Elenbaas.
Dose effectiveness and safety of butorphanol in acute migraine headache.
This study was undertaken to compare the effectiveness and safety of three dosage levels of butorphanol in 52 patients with acute, severe migraine headache. After baseline evaluation, patients were given a dose of butorphanol 1.0, 2.0, or 3.0 mg intramuscularly on a double-blind basis. Assessments of pain intensity and pain relief using 100 mm linear analog scales (LAS), vital signs, and medication side effects were made at 15, 30, 45, and 60 minutes after the dose. All three treatment groups were similar in baseline characteristics. Each dose of butorphanol demonstrated a significant decrease in pain intensity LAS compared to baseline and increase in pain relief LAS over the observation period. The majority of analgesic response was observed at the first (i.e., 15-min) assessment. Doses of 2.0 and 3.0 mg produced significantly greater analgesia than did 1.0 mg at all posttreatment evaluations. No significant difference was apparent between the 2.0- and 3.0-mg doses. Adverse cardiovascular and respiratory depressant effects were not observed. An analgesic response to butorphanol 2.0 and 3.0 mg is clearly and rapidly evident and near maximum 30-45 minutes after administration. We conclude that in these doses butorphanol provides effective and safe analgesia for patients with acute migraine headache.
Prophylactic penicillin for intraoral wounds.
We conducted a prospective, double-blind, placebo-controlled study in adult patients to determine whether prophylactic penicillin prevents infection in intraoral lacerations secondary to minor trauma or seizures. Uninfected full-thickness, mucosal-only, or through-and-through wounds presenting within 24 hours of injury were considered. Management consisted of cleansing, irrigation, debridement, and closure as indicated: no topical antibiotics were applied. Patients were randomly assigned to receive penicillin VK 500 mg or identically appearing placebo four times daily for five days. Home wound care was standardized and patients were followed for a minimum of four or five days. Infection was assessed clinically. Seventy-six patients were enrolled and 62 completed the study. Penicillin (30) and placebo (32) groups were similar in all parameters except wound etiology; assault was more common in the placebo group (P = .02). Two infections occurred in patients receiving penicillin, and six infections were seen among placebo-treated patients (P = .05, beta = 0.17). When patients poorly compliant with therapy were eliminated from analysis, none of the penicillin-treated patients and five of the placebo-treated patients developed infections (P = .027). Our data suggest that patients with intraoral wounds may benefit from prophylactic penicillin if compliant with their therapy. More studies are needed to further delineate the usefulness of prophylactic antibiotics for these wounds.
Aerosolized metaproterenol in the treatment of asthmatics with severe airflow obstruction. Comparison of two delivery methods.
The bronchodilator response to metaproterenol delivered by metered-dose inhaler (MDI) with a spacer device (Aerochamber [A]) and by jet nebulizer was studied in 44 asthmatic patients who presented to the emergency department with acute severe (FEV1 less than 50 percent predicted) airflow obstruction. The delivery method was randomized, double-blinded and placebo controlled. The A group received one puff of metaproterenol every five minutes for a total of three puffs (1.95 mg). The jet nebulizer group received 15 mg of metaproterenol by continuous nebulization over ten minutes. Only about 2.75 mg of the original 15 mg delivered by jet nebulizer was calculated to be available for inhalation due to the inefficiencies of the delivery system. The mean percentage of improvement in FVC and FEV1 in the A group was 33.5 and 49.0 percent, respectively. The mean percentage of improvement in FVC and FEV1 in the jet nebulizer group was 22.8 and 33.0 percent, respectively. There was no significant difference in the mean percentage of improvement values between the two groups. We were unable to demonstrate a difference in bronchodilator response to metaproterenol delivered by MDI-A and jet nebulizer in emergency department asthmatics with acute severe airflow obstruction.
The effect of in-line filtration on tobramycin delivery.
The purpose of this study was to determine if the presence of an in-line 0.22 mu cellulose ester membrane filter would hamper the delivery of a common adult dose of tobramycin sulfate. Solutions of tobramycin sulfate 80 mg in 100 ml D5W were assayed after 30 minute infusions through unfiltered and filtered administration sets; solutions post-flush of filtered sets were also assayed. Assay was done by Emit-QST. The results indicated that there was no significant difference in the delivery of tobramycin sulfate, regardless of the presence of an in-line filter. Solutions post-flush contained about ten percent of the drug, reflecting the amount in solution that remained in the tubing. Since ten percent can alter pharmacokinetic monitoring for patient dosing, a consistent procedure for flushing filtered administration sets should be adopted to enhance accuracy of such determinations.
Bretylium in hypothermia-induced ventricular fibrillation in dogs.
We undertook a study to determine the ability of intravenous bretylium to cause "chemical defibrillation" or facilitate electrical defibrillation of hypothermia-induced ventricular fibrillation in the dog. Two groups of ten dogs were cooled to 22 C and placed into ventricular fibrillation. Following initiation of cardiopulmonary resuscitation, bretylium 15 mg/kg or normal saline was administered and the dogs were defibrillated according to a standard protocol. Both groups were equivalent in mean arterial pressure and arterial blood gases throughout the investigation. Seven dogs in each group were converted from ventricular fibrillation to an organized cardiac rhythm (P greater than .05). Despite the possible value of prophylactic bretylium in the setting of hypothermia, its use as active treatment for hypothermia-induced ventricular fibrillation in dogs does not seem to be beneficial.
Prediction of serum theophylline levels.
Because theophylline (T) has a narrow therapeutic index, serum concentrations resulting from previous outpatient therapy must be considered when planning intravenous (IV) aminophylline dosage in the emergency department (ED). Facilities to measure serum T concentrations rapidly are not available in all institutions. We therefore studied our ability to predict serum T concentrations in asthma or COPD patients, and assessed the probable outcomes if dosing decisions had been based on these predictions. Forty adult patients (mean age, 41.5 years) who had taken a theophylline preparation within 12 hours of ED presentation were studied. Serum T concentration was predicted based on each patient's medication history and the use of standard pharmacokinetic equations, and was compared with the patient's actual T level. The mean actual T concentration was 12.7 +/- 6.62 micrograms/mL, while the mean predicted T concentration was 11.4 +/- 5.37 micrograms/mL. If the predicted T concentrations had been used to plan subsequent IV aminophylline dosing, 68% of patients would have received therapy likely to place them within the range of 10 to 20 micrograms/mL; 15% would have received too little aminophylline, and 17% too much. Comparable results are noted if aminophylline dosing had been based simply on the elapsed time since the patient's last oral T dose. While IV aminophylline dosing decisions can be made safely in many patients by considering their medication history or predicting serum T concentration, inappropriate and possibly dangerous therapy will result in a sizable, unpredictable minority. Aminophylline dosing in the ED ideally should be done with knowledge of the patient's base-line theophylline level.
Evaluation of prophylactic oxacillin in cat bite wounds.
A prospective, double-blind, placebo-controlled study was undertaken to determine the influence of prophylactic oxacillin on the frequency of infection in cat bite wounds. Adult patients with uninfected full-thickness wounds presenting within 24 hours of injury were considered. Emergency department management consisted of cleansing, irrigation, debridement, and closure as indicated; no topical antibiotics were applied. Patients were randomly assigned to receive oxacillin 500 mg qid for five days or identically appearing placebo. Home wound care was standardized and patients were observed at least every two days for a minimum of five days, or until wounds were sufficiently healed to allow discharge from the study. Clinical assessment of infection was confirmed microbiologically when possible. Twelve patients were admitted and 11 completed the study. Oxacillin (n = 5) and placebo (n = 6) groups were identical in sex, age, number of wounds per patient, wound location and type, delay to emergency department presentation, length of follow-up observation, medication compliance, and adequacy of home wound care. Four of six patients receiving placebo, but none of the five receiving oxacillin, developed a wound infection (P = .045). Material obtained from three of these four patients yielded Pasteurella multocida as the responsible organism. Prophylactic oxacillin was thus associated with a significant reduction in the frequency of infection following cat bites. We recommend such therapy in the care of these wounds.
Evaluating the medical literature. Part II: Statistical analysis.
We have attempted to provide sufficient information to enable the reader to verify that the investigator has used an appropriate statistical test for the evaluation of his study data. We have not discussed the actual calculation of the tests presented. With the wide availability of computers and programmable calculators, it is safe to assume that the investigator has performed the necessary mathematics accurately. Instead of assessing the accuracy of these calculations, the reader should verify that the correct statistical test was chosen in the first place. The astute reader may be surprised at how frequently an incorrect test is used. Merely achieving statistical significance does not characterize the author's data as clinically important. Neither does it, in and of itself, prove one agent superior to another nor prove a cause-and-effect relationship between two variables. When appropriately interpreted, however, statistical analysis can be a very useful and powerful tool in helping to arrive at the "truth."
Evaluating the medical literature. Part I: Abstract, introduction, methods.
In this installment on critical evaluation of medical literature, we have discussed the Abstract, Introduction, and Methods sections. A great deal of information is placed in the methodology section of any paper. To critically evaluate a research publication, one must evaluate the methodology, for evaluation of the results of an investigation is meaningless if the methodology is unsound.
Evaluating the medical literature, Part III: Results and discussion.
This series has addressed the basic segments of a research publication and discussed critical considerations that a reader should make as he progresses through the segments. The questions listed in Figure 3 may be helpful to guide the reader through the evaluation process.
Therapeutic bibliography of critical care.
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Failure of peak expiratory flow rate to predict hospital admission in acute asthma.
Our study evaluated the ability of early peak expiratory flow rates (PEFR) to be predictive of hospital admission while double blinding the measurements and using a standardized treatment protocol and specific admission criteria. The measurements were recorded prior to and after initial therapy. Eighty-six acute asthmatic episodes in 51 patients were analyzed. Nine (10.5%) of the episodes resulted in hospitalization; 77 (89.5%) resulted in discharge. No correlation with admission was found for the initial PEFR, a second PEFR following treatment, or the differences between these two values. Our study indicates that early PEFRs alone are not useful predictors of the need for hospital admission. Although a significant number of patients in our study population presented with severe airflow obstruction, they responded sufficiently to treatment to permit discharge.
Prophylactic oxacillin in dog bite wounds.
This prospective, double-blind, placebo-controlled study was undertaken to determine the value of prophylactic oxacillin in dog bites. Adult patients with uninfected full-thickness wounds presenting within 24 hours of injury were considered. Management consisted of cleansing, irrigation, debridement, and closure as indicated; no topical antibiotics were applied. Patients were randomly assigned to receive oxacillin 500 mg QID x 5 days or identically appearing placebo. Home wound care was standardized an patients were observed at least every 2 days. Clinical assessment of infection was confirmed microbiologically. Sixty-three patients were admitted and 46 completed the study. Oxacillin (22) and placebo (24) groups were identical in sex, age, number of wounds per patient, wound location and type, number of open and closed wounds, delay to presentation, length of follow-up observation, medication compliance, and adequacy of patient wound care. Two infections of the hand occurred in patients receiving oxacillin; no infections were seen among placebo-treated patients (P = NS). Prophylactic oxacillin was not associated with improved outcome. We do not advise the use of prophylactic antibiotics in dog bite injuries treated within 24 hours of accident.
Use of peak expiratory flow rates to eliminate unnecessary arterial blood gases in acute asthma.
Arterial blood gas (ABG) measurements are used frequently in acute asthma. Because ABGs are expensive and may have significant side effects, a method is needed to identify those patients at risk for a significantly abnormal ABG. We studied the use of peak expiratory flow rates (PEFR) to identify those patients at such risk. Data from 89 emergency visits by 51 asthmatic patients were analyzed. A small but significant correlation between ABG parameters and PEFR was observed (P less than 0.05). No patient with a PEFR greater than or equal to 25% predicted has a PaCO2 greater than 45 mm Hg or pH less than 7.35. This suggests that only those patients with a PEFR less than 25% predicted are at risk for significant hypercarbia or acidosis. We concluded that PEFR may be used as a simple screening tool to safely eliminate ABGs in at least 40% of acute asthmatic patients.
On the disulfiram-like activity of moxalactam.
A three-way crossover study was undertaken in 10 healthy subjects to characterize the reported disulfiram-like activity of moxalactam and to assess its influence on ethanol and acetaldehyde metabolism. On different occasions separated by at least 2 wk subjects were given in random order: 0.5 gm/kg ethanol orally, 0.5 gm/kg ethanol followed in 1 hr by 1.0 gm IV moxalactam, and 1.0 gm IV moxalactam every 8 hr for four doses followed by 0.5 gm/kg ethanol. Mean ethanol elimination rates of 13.1 +/- 0.76, 10.1 +/- 1.11, and 10.9 +/- 1.06 mg/dl/hr (mean +/- SEM) were observed in the three protocols, respectively. Corresponding mean estimated acetaldehyde clearance rates were 103.7 +/- 15.55, 92.8 +/- 13.79, and 97.3 +/- 10.41 l/min (mean +/- SEM). While no consistent moxalactam effect on ethanol or acetaldehyde elimination was observed, two subjects experienced mild disulfiram-like reactions to ethanol after moxalactam pretreatment. In one subject this reaction was associated with markedly elevated blood acetaldehyde concentrations. We conclude that moxalactam pretreatment may induce a disulfiram-like reaction after ethanol ingestion in some, probably due to inhibition of aldehyde dehydrogenase, and that alcoholic beverages are contraindicated in patients receiving moxalactam. We suggest, however, that such reactions will not occur when moxalactam is given after ethanol ingestion.
Prophylactic antibiotics and dog bite wounds.
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Influence of clinical pharmacist consultations on the use of drug blood level tests.
The effect of a controlled-ordering program (prior authorization by a clinical pharmacist) on the number and cost of drug blood level assays performed at the Truman Medical Center (Kansas City, MO) was studied. Drug assay orders for aminoglycosides, phenobarbital, phenytoin, quinidine, theophylline, salicylate, thiocyanate, and propranolol, laboratory costs, and hospital census were reviewed retrospectively. The programs compared were: (1) control (July to December 1977)--drug blood level assays were ordered at physicians' discretion, and (2) study (January 16, 1978 to January 15, 1979)--all pharmacokinetic assays had to be approved by a pharmacist. A significant (p less than 0.001) reduction in the number of assays performed per month (40%) and in the assay cost per month (44%) occurred during the study period. The program was estimated to save $12,086.61 annually. The policy of requiring pharmacist approval of drug assay orders reduced the improper use and cost of pharmacokinetic monitoring.