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Biomedical subjects

R L Wears

Publications and source records attributed to R L Wears.

10 recordsLinked to original sources
PubMed1992

Length-based endotracheal tube and emergency equipment in pediatrics.

HYPOTHESIS: Pediatric endotracheal (ET) tubes can be accurately selected based on body length using a specialized emergency tape. POPULATION: Derivation set: Two hundred five children undergoing elective surgery. Validation set: Two hundred thirteen children undergoing elective surgery. Each child served as his or her own control. METHODS: Derivation phase: Two hundred twenty-one children undergoing ET intubation for elective surgery had their body length and leak pressures measured. The 205 children who had leak pressures between 10 and 40 cm H2O constituted the derivation set. The body length for a given ET tube size was derived from the interquartile range of patient lengths in this derivation set. Sizes for other resuscitative equipment items were chosen by a panel of experts using a modified Delphi technique. This information was placed by length on a color-coded tape. Validation phase: The tape was validated by using it to select ET tube size in another group of 203 children undergoing elective surgery. Criteria for acceptable fit in this group included leak pressure as above and the anesthesiologists' decision to accept the tube size or to retintubate. In the validation phase, length-based ET tube selections were compared with age-based rules: (age + 16)/4, and (age + 18)/4. RESULTS: The tape selected the appropriate ET tube size by leak pressure criterion in 77% of the cases and was within +/- 0.5 mm of the "correct" size 99% of the time. This was significantly better (P less than .005) than two widely used age-based rules, which gave the correct initial size in only 47% and 9% of these cases, and were within +/- 0.5 mm for 86% and 59%. The anesthesiologists chose to continue with the tape-sized tube rather than to reintubate in 89% of cases. CONCLUSION: A system for length-based selection of emergency equipment represents a significant adjunct to emergency physicians and paramedics who must deal with critically ill children. Length-based ET tube selection is clearly superior to age-based rules, which are difficult to remember and require accurate estimation of a patient's age.

Body Height↗
PubMed1992

Prophylactic antibiotics for the prevention of infectious complications including empyema following tube thoracostomy for trauma: results of meta-analysis.

Since 1977, six clinical trials have been performed on the subject of routine antibiotic prophylaxis in patients requiring tube thoracostomy for trauma. No definitive conclusions have been reached regarding the efficacy of antibiotic use in this setting. The results of these clinical trials were pooled to generate an unbiased estimate of the efficacy of antibiotic prophylaxis for tube thoracostomy using the technique of meta-analysis. Meta-analysis is a statistical method for synthesizing results from separate but similar experiments, grouping them, and comparing each to the null hypothesis. Meta-analysis allows synthesis of all of the available data on antibiotic prophylaxis for tube thoracostomy to resolve the controversy surrounding this issue generated by different but similar clinical studies with conflicting results. Despite different conclusions of value when taken individually, the combined analysis does not support the null hypothesis (no effect of antibiotics). The statistical method is highly significant despite different mechanisms of injury, pathologic findings, and antibiotics employed.

Anti-Bacterial Agents↗
PubMed1991

An analysis of emergency physicians' cumulative career risk of HIV infection.

STUDY OBJECTIVE: To determine point and range estimates of the cumulative career risk of occupationally acquired human immunodeficiency virus (HIV) infection by emergency physicians as well as to determine if the efficacy of universal precautions was seriously diminished by prolonged risk over time. DESIGN: Monte Carlo estimation of a mathematical model of cumulative risk. Eight scenarios were estimated for high versus low prevalence of HIV, no precautions versus universal precautions, and prevalence increasing to a steady state versus peaking and then declining. MEASUREMENTS AND MAIN RESULTS: For high-prevalence areas, not using universal precautions, and assuming HIV seroprevalence increases to a steady-state level, the median estimate of cumulative risk of HIV infection over a 30-year career was 1.4% (90% of tolerance range, 0.2% to 14.0%); for low-prevalence emergency departments, the median was 0.1% (0.001% to 3.6%). Universal precautions with a presumed effectiveness of approximately 40% resulted in an approximate 30% decrease in risk. CONCLUSIONS: Although the per-exposure risk is small, the cumulative risk of HIV infection may be disproportionately large. The efficacy of universal precautions does not appear to be substantially diminished over time.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Diagnostic and prognostic importance of comparing the initial to the previous electrocardiogram in patients admitted for suspected acute myocardial infarction.

Two hundred fifty-eight patients were admitted to the hospital for suspected acute myocardial infarction. Electrocardiograms recorded on admission (initial ECG) and the most recent available electrocardiogram recorded before admission (previous ECG) were compared to determine whether changes from the previous to initial ECG predicted acute myocardial infarction or complications of coronary artery disease. Initial ECGs were classed as either positive or negative, with positive indicating either infarction, injury, ischemia, strain, left ventricular hypertrophy, left bundle branch block, or paced rhythm. Negative ECGs were those that did not include any of the positive criteria. Positive and negative ECGs were subgrouped as showing change or no change from previous ECG. We found that patients with a negative initial ECG that had changed from the previous ECG had a 2.1 times greater risk for requiring interventions than those patients whose ECGs were unchanged. We also found that patients with a positive initial ECG that had changed from the previous ECG had a greater risk for interventions (2.0 times), complications (2.6 times), life-threatening complications (4.2 times), and acute myocardial infarction (6.6 times) than the sum of patients in all other ECG categories. We conclude that change is a useful predictor for interventions in patients with negative initial ECGs and a useful predictor for interventions, complications, and acute myocardial infarction in patients with positive initial ECGs.

Coronary Disease↗
PubMed1979

Circumventing the Henderson-Hasselbalch equation.

Prompt blood-gas analysis consisting of pH, PCO2, and PO2 is now almost universally accessible. PCO2 directly conveys the role of the respiratory mechanism in any acid-base disturbance. The metabolic condition, however, is hidden in a relationship between pH and PCO2 that is most faithfully expressed by the cumbersome Henderson-Hasselbalch equation (HHE). Two methods of quickly determining metabolic status from pH and PCO2, without resorting to the HHE, are discussed. The first method is well known and adjusts pH to represent only metabolic state by quantitatively cancelling the influence of hyper- or hypoventilation. The second method, not previously reported, uses measured pH to estimate the ratio [HCO3-]/PCO2, which, when multiplied by PCO2, equals bicarbonate ion concentration.

Acid-Base Imbalance↗
PubMedDate not supplied

Objective determination of the optimal red blood cell count in diagnostic peritoneal lavage done for abdominal stab wounds.

The purpose of this study was to determine objectively the optimal value or positivity criterion for red blood cell counts in diagnostic peritoneal lavage in stab wounds to the anterior abdomen. Our study group consisted of 91 consecutive adults with abdominal stab wounds who underwent peritoneal lavage. We excluded those patients who met criteria for immediate laparotomy and those with negative stab wound exploration. We divided the patients into two groups based on outcome. Group 1 consisted of those who had undergone laparotomy and had findings that required surgical intervention. Group 2 patients had either undergone laparotomy but had no injury requiring surgical intervention or had no surgery and a benign hospital course and follow-up. Receiver operator characteristic analysis was done on the diagnostic peritoneal lavage RBC counts for both groups. The overlap between the groups was minimal, with 75% of patients in Group 1 having > 120,000 RBC/mm3 and 75% of patients in Group 2 having < 486 RBC/mm3 in the lavage effluent. Using the observed probability of 23.1% of patients with abdominal stab wounds requiring surgery, a RBC count of 50,000/mm3 discriminated best those patients who required surgery from those who did not.

Abdominal Injuries↗