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Biomedical subjects

J W Davis

Publications and source records attributed to J W Davis.

At least 163 records · Page 9Linked to original sources
PubMed1991

The significance of critical care errors in causing preventable death in trauma patients in a trauma system.

The regionalization of trauma care has led to a decrease in preventable death after injury. This decrease has been attributed to earlier resuscitation and surgical intervention. Little emphasis, however, has focused on the critical care phase of trauma patient management. This study was undertaken to determine the significance of critical care errors (CCEs) on preventable mortality and morbidity in a regionalized system of trauma care. The records of 12,910 trauma patients admitted to six trauma centers over a three-year period were reviewed. The cause and preventability of death was determined by a panel of trauma experts. Critical care errors occurred in 151 (23%) of all patients with errors occurring during any phase of care. The CCEs were identified in 38 of 125 (30%) deaths of patients with errors in some phase of care. The CCEs were implicated as the cause of death in 30 (48%) of the 62 preventable deaths. The proportion of preventable deaths attributable to CCEs was higher than the proportion of preventable death attributable to errors in the resuscitative and operative phases of care (p less than 0.001, chi-square). These data indicate that CCEs significantly contribute to preventable mortality and morbidity in trauma patients. It is imperative that physicians caring for trauma patients possess expertise in the critical care management of injured patients.

Cause of Death↗
PubMed1991

Burnished versus nonburnished application of citric acid to human diseased root surfaces: the effect of time and method of application.

Citric acid (pH = 1) was applied passively or by vigorous burnishing for 3 or 5 minutes to diseased human root surfaces following root planning in vitro. Control surfaces were similarly treated with saline only. Teeth were fixed in glutaraldehyde, dehydrated, freeze-dried, and sputter coated with gold for scanning electron microscopic viewing. Results suggested that optimal exposure of collagen and demineralization occurred with the burnishing application of citric acid for 3 minutes. Although somewhat similar results were found with passive application for 5 minutes, the result of the burnishing application for 5 minutes was that the root was overdemineralized or that the exposed collagen was completely obscured by an amorphous layer that was suggestive of protein denaturization.

Citrates↗
PubMed1991

Prospective evaluation of epidural and intravenous administration of fentanyl for pain control and restoration of ventilatory function following multiple rib fractures.

To evaluate the efficacy of opiate administration regimens, 32 patients with multiple rib fractures were prospectively randomized to receive either continuous epidural (ED) or continuous intravenous (IV) infusions of fentanyl. Dosage was titrated to individual subjective pain relief. Ventilatory function tests (VFTs), arterial blood gases (ABGs), and visual analog scores were obtained before and after the institution of analgesia. Post-analgesia values were compared with pre-analgesia values using a two-tailed paired t-test looking for significant changes produced by the analgesic method. Both methods significantly improved analog pain scores. The ED method produced improvement in both maximum inspiratory pressure (MIP) and vital capacity (VC), whereas IV analgesia only produced improvement in VC. Intravenous fentanyl produced increases in PaCO2 and decreases in PaO2, whereas no significant changes in ABGs were observed with ED fentanyl administration. Side effects were similar between the groups, with pruritus being more pronounced with ED fentanyl administration. The data demonstrate that the continuous ED fentanyl method offers excellent relief of pain and improvement in ventilatory function and has distinct advantages over IV fentanyl administration with respect to changes in ABGs and MIP. The continuous infusion of epidural opiates should be the preferred analgesic method for patients at high risk of developing pulmonary complications following multiple rib fractures.

Adult↗
PubMed1991

Base deficit as a sensitive indicator of compensated shock and tissue oxygen utilization.

To determine the relationship of the arterial base deficit (BD) to physiologic indicators of shock and resuscitation--heart rate, mean arterial pressure (MAP), cardiac output (CO), arteriovenous oxygen difference (AVO2), mixed venous oxygen saturation (VSAT) and oxygen delivery to consumption ratio (RATIO)--16 swine were monitored invasively, bled 40 per cent of their calculated blood volume and resuscitated with crystalloid and blood. During hemorrhage, the MAP, CO, VSAT and RATIO decreased and the BD and AVO2 increased. One hour after hemorrhage, but before crystalloid infusion, the MAP, VSAT and RATIO had increased significantly from previous levels and the AVO2 had narrowed significantly, while the BD showed no significant change. All parameters returned to baseline with resuscitation. BD accurately reflected the hemodynamic and tissue perfusion changes associated with hemorrhagic shock and resuscitation in this model. BD can be used as an indicator of the severity of the shock state and the efficacy of resuscitation when invasive monitoring is impractical or not available. BD was more reflective of the true volume deficit during compensated shock than other physiologic variables in this study.

Acid-Base Imbalance↗
PubMed1990

A critical review of bone mass and the risk of fractures in osteoporosis.

The usefulness of various bone mineral measurement techniques is a subject of current controversy. In order to explore whether disparate conclusions may have arisen from differences in analytic methodology, data from published reports of bone mass and nonviolent fractures have been reanalyzed in terms of fracture risk. In the large majority of studies, reduced bone mass was associated with an increased risk of fractures. However, the magnitude of the relationship varied much more among cross-sectional studies than among prospective studies, suggesting that bias related to subject selection and/or postfracture bone loss may have strongly influenced the cross-sectional findings. We conclude that more emphasis should be given to the results of prospective studies, and that more attention should be paid to subject selection in all investigations. Analyzing and presenting results in terms of fracture risk would probably reduce the level of confusion in the field and provide more clinically relevant information. These issues are also applicable to studies of potential fracture risk factors other than bone mass, such as bone structure and bone quality.

Aged↗
PubMed1990

Fracture prediction models for osteoporosis prevention.

Fracture prediction models have been developed that can estimate an individual's cumulative or lifetime fracture risk on the basis of bone mineral measurements and other factors. Examples illustrate how estimates of cumulative fracture risk might be influenced by initial age and level of bone mass, as well as by anticipated bone loss rate. New data regarding bone loss rates, fracture costs, and fracture risk factors should be incorporated to improve the accuracy of existing models. Such models could then be used for cost-benefit analysis to explore optimal treatment strategies.

Bone Density↗
PubMed1990

The asymptomatic patient with suspected myocardial contusion.

Diagnostic criteria and guidelines for hospital admission for suspected myocardial contusion (MCC) remain unclear. This study defines and examines the clinical sequelae of patients admitted with a suspicion of MCC. Criteria for observation following isolated, minor blunt chest trauma are suggested. Hospital and trauma registry records of patients admitted over a 33-month period with suspected MCC were reviewed. Conventional evaluation criteria, cardiac-related complications, and associated injuries were analyzed for 524 patients. Twenty-eight cardiac-related complications occurred in 27 of 524 patients (5%). These complications included 23 dysrhythmias, 3 infarctions, and 2 pericardial effusions. There were 23 patients with abnormal admission electrocardiograms and 4 with normal ones. Of the latter, one patient developed dysrhythmia 4 hours after admission, and three had other major multi-system injuries requiring admission to the intensive care unit. The overall incidence of cardiac-related complications in minimally injured patients was 0.1%. There were no complications in patients with isolated chest wall contusions, a normal admission electrocardiogram, and a normal rhythm at 4 hours. There was no significant association between creatine phosphokinase isoenzymes or echocardiogram and cardiac-related complications. The complete absence of significant cardiac sequelae in patients with isolated chest wall contusion, normal admission and 4-hour electrocardiograms, and no other associated major injuries suggests that these patients need not be admitted.

Adult↗
PubMed1990

Venous thromboembolism in patients with major trauma.

The risk of venous thromboembolism after trauma is thought to be high, but the specific risk factors and the incidence of venous thromboembolism in the trauma population are poorly defined. Between October 1, 1987, and March 1, 1988, 719 patients were evaluated; 542 had no risk factors and 177 had at least 1 risk factor. No venous thromboembolism occurred in any of the 542 patients without a risk factor, whereas 12 of 177 patients (7%) with at least 1 risk factor had a venous thromboembolism. Pneumatic compression hose was the most common form of prophylaxis used, but it could not be applied to 35% of limbs because of plaster immobilizers, external fixators, complex wounds, or traction. In the high-risk group, 25 patients (14%) received no prophylaxis because of a physical impediment to application of these hose and a contraindication to anticoagulation. Age greater than 45 years was the only risk factor predictive of venous thromboembolism by logistic regression analysis. Patients with more than one risk factor had a significantly higher incidence of venous thromboembolism than those with only one risk factor. We conclude that a selected subgroup of trauma patients appears to be at risk of venous thromboembolism and should receive prophylaxis. Approximately one in seven high-risk patients cannot receive anticoagulant or mechanical prophylaxis because of their injuries.

Adult↗
PubMed1990

Microsurgical transfer of the rectus abdominis muscle using the superior epigastric vessels.

A microsurgical transplant of the rectus abdominis muscle based on its superior pedicle is described. This procedure represents a salvage maneuver used in a patient in whom the inferior pedicle was found to have been previously injured. Vessels of adequate caliber and a pedicle of sufficient length were found by dissecting the superior epigastric pedicle to the level of the costal margin. In cases in which rectus flap harvest is complicated by a damaged deep inferior epigastric pedicle, we recommend exploration of the superior pedicle before abandoning the flap.

Abdominal Muscles↗
PubMed1990

Implications of admission hypothermia in trauma patients.

Hypothermia is common after severe injury, and has been associated with an increased mortality rate in patients stratified by anatomic indices of injury severity. In this retrospective study of 173 patients, early post-traumatic hypothermia was found to correlate with physiologic indicators of volume deficit, independently of the amount of intravenous fluid received. There was no correlation found between admission core temperature and time from injury, blood alcohol, or presence of severe closed head injury. Hypothermic patients (less than 35 degrees C) had a lower predicted probability of survival and a higher mortality rate than euthermic patients (greater than or equal to 35 degrees C). However, when patients were stratified by physiologic and anatomic indicators of injury severity, mortality rates among the euthermic and hypothermic patients were not significantly different. Early post-traumatic hypothermia does not appear to exert an independent effect upon outcome.

Adult↗
PubMed1990

The effects of aortic crossclamping and resuscitation on intracranial pressure, cerebral blood flow, and cerebral water content in a model of focal brain injury and hemorrhagic shock.

Aortic crossclamping (AOXC) is performed frequently in hypotensive trauma patients who may have had a head injury. The effect of AOXC on the injured brain is unknown. We studied the effect of AOXC on mean arterial pressure (MAP), intracranial pressure (ICP), cerebral blood flow (CBF), cerebral perfusion pressure (CPP), and cerebral water content in a porcine model of focal cryogenic brain injury. Four groups of animals were studied: Group I--brain injury only; Group II--brain injury and AOXC; Group III--brain injury with hemorrhage and AOXC; and Group IV--AOXC only. Focal cryogenic grain injury increased the ICP in Groups I-III. Aortic crossclamping increased MAP, CBF, ICP, and CPP after hemorrhage in Group III. Following declamping and resuscitation there were no differences between the groups in any studied variable. Cerebral water content at the site of the focal brain injury was greater than in nonlesioned cortex but there was no significant difference between groups despite a greater positive fluid balance in hemorrhaged animals. AOXC improved perfusion to the injured brain without a significant increase in ICP. Increased MAP induced by AOXC and large fluid resuscitation appeared to have no detrimental effect on ICP, CBF, cerebral water content, or CPP in this model of brain injury.

Animals↗
PubMed1990

Aerobic biodegradation of vinyl chloride in groundwater samples.

Studies were conducted to examine the biodegradation of 14C-labeled vinyl chloride in samples taken from a shallow aquifer. Under aerobic conditions, vinyl chloride was readily degraded, with greater than 99% of the labeled material being degraded after 108 days and approximately 65% being mineralized to 14CO2.

Aerobiosis↗
PubMed1990

Ellipsoidal shell subtraction model of right ventricular volume. Comparison with regional free wall dimensions as indexes of right ventricular function.

Pulse-transit sonomicrometry was used to measure the base-apex (a), anteroposterior (b), and septal-free wall (c) diameters of the left ventricle and the septal-free wall diameter of the right ventricle (d) in eight excised and three isolated, pump-perfused canine heart preparations, as well as in nine conscious dogs. In the three perfused hearts and in four of the excised hearts, right ventricular free wall regional segment lengths and segment area also were assessed. Biventricular volumes were measured directly with intracavitary balloons in all isolated hearts. When left ventricular balloon volume was held constant, relations between right ventricular free wall dimensions and right ventricular balloon volume were highly linear. With increments in left ventricular volume, however, these relations remained linear but shifted progressively upward, indicating an independent relation between right ventricular free wall dimensions and left ventricular cavitary volume. An ellipsoidal shell subtraction model (pi/6.abd minus right ventricular free wall volume) was developed to estimate right ventricular cavitary volume from cardiac dimensions. With this method, a highly linear relation was observed between calculated right ventricular volume and right ventricular balloon volume (mean r = 0.99 +/- 0.01). Moreover, this relation appeared to be independent of changes in left ventricular balloon volume. With the shell subtraction model, dynamic right ventricular volume was computed in nine conscious dogs, and in four, stroke volume derived from dimensions was compared with right ventricular stroke volume measured with ultrasonic flow probes. A highly linear relation was observed, suggesting the accuracy of the shell subtraction method in vivo. Right ventricular end-systolic pressure-volume and stroke work/end-diastolic volume relations then were evaluated, and both proved to be highly linear in the right ventricle (both mean r = 0.99 +/- 0.01). Thus, the shell subtraction model allows a simple estimate of dynamic right ventricular volume in the intact heart and facilitates assessment of right ventricular performance in vivo.

Animals↗
PubMed1990

The effects of dopamine on myocardial functional recovery after reversible ischemic injury.

Dopamine frequently is used to improve cardiac performance after acute myocardial ischemia. Inotropic agents, however, increase myocardial oxygen demand and could potentially delay recovery from ischemic injury. To evaluate this problem, we studied eight chronically instrumented dogs in the conscious state and performed two 15-minute coronary occlusions 48 hours apart. After one of the occlusions, either dopamine (15 micrograms/kg/min) or saline placebo was administered intravenously from 1.0 to 1.5 hours of reperfusion. The alternative infusion was given during the second study. Preload recruitable work area, the area beneath the stroke work versus end-diastolic length relationship, was used to assess intrinsic myocardial performance. Ischemia decreased preload recruitable work area to 13% of control after both occlusions. After reperfusion, a 30-minute dopamine infusion acutely increased myocardial function nearly threefold as compared with placebo. Myocardial performance after dopamine administration, however, was significantly depressed compared with placebo throughout the remaining 24 hours of reperfusion (p less than 0.01). These data indicate that dopamine may impair functional recovery after ischemic myocardial injury and suggest that inotropic interventions should be used in this setting only when absolutely indicated.

Animals↗
PubMed1990

Complications in evaluating abdominal trauma: diagnostic peritoneal lavage versus computerized axial tomography.

We reviewed our experience with 2,809 DPL's and 1,331 CT's obtained in the resuscitative phase over a 3-year period in our trauma system to determine the significant complications associated with each modality. There were 25 DPL complications: eight false negatives, three false positives, and 14 technical errors. There were 46 CT complications including 25 false negative scans, three false positive scans, and 18 delays to the operating room from obtaining abdominal CT evaluation, with two of these delays resulting in preventable deaths. Although both modalities had low complication rates (0.9% DPL vs. 3.4% CT), DPL was associated with less preventable mortality and morbidity than CT in the evaluation of abdominal trauma.

Abdominal Injuries↗
PubMed1990

Blunt carotid artery dissection: incidence, associated injuries, screening, and treatment.

Blunt carotid dissection (BCD) is a rare injury occurring in less than one in 1,000 victims of blunt injuries. Using a 4-year experience in a trauma system with 14 cases of BCD, we performed a matched blunt trauma patient case-control analysis to determine if there were patterns of injuries that were associated with increased risk of BCD. Patients with combinations of head, facial, and cervical spine injuries with or without extremity fractures proved to be at significantly increased risk for BCD. Duplex scanning appears to be a useful screening tool for these patients. Anticoagulation was the preferred treatment once neurologic deficits were present.

Adult↗