Biomedical subjects
Publications and source records attributed to J R Hedges.
A psoas abscess is infrequently diagnosed on initial presentation. This report reviews the presentation of a patient with a complicated psoas abscess. The pathophysiology and the clinical and laboratory presentation of patients with this disease entity are reviewed.
Recent case reports have implicated the pneumatic antishock garment (PASG) in the development of the compartment syndrome in the lower extremities. The present study used the anterolateral compartment of the canine hindlimb to model the effect of the PASG on tissue pressure within the compartment (Pc). Prior to inflation of the garment, baseline Pc was 5.3 mm Hg. PASG inflation to 60 mm Hg for 20 minutes resulted in an increase in Pc of 75.0 mm Hg over baseline values. The rise in Pc was reduced significantly following hemorrhage of the animal, measuring 65.8 mm Hg at a mean arterial pressure of 70 to 80 mm Hg and 62.5 mm Hg at a mean arterial pressure of 40 to 50 mm Hg. In the immediate postarrest state, Pc rise after a five-minute inflation of the garment was 57.5 mm Hg. In all cases, Pc promptly returned to baseline values when the PASG was deflated, and there was no significant change in Pc following deflation of the garment under conditions of normotension, hemorrhagic hypotension, and in the immediate postarrest state. Our results suggest that the level of arterial pressure may contribute to Pc rise during PASG inflation.
A retrospective analysis was made of 265 female outpatients who initially presented to an emergency department with a complaint of amenorrhea, vaginal bleeding, or abdominal/pelvic pain. The patients were discharged from the emergency department pending results of a serum pregnancy test. Forty-five of the patients were subsequently found to have an elevated (greater than 5 mIU/mL) beta human chorionic gonadotropin (HCG) level. Six of the patients had an ectopic pregnancy; their beta HCG levels ranged from 19 to 265 mIU/mL. A detectable beta HCG level less than 500 mIU/mL had a 33% probability of an ectopic pregnancy in the study group. Historical features, physical examination, and laboratory parameters were of limited value for identification of minimally symptomatic outpatients at risk for an ectopic pregnancy. No study patient had a systolic blood pressure of less than 86 mm Hg on presentation. A comparison group of 29 patients admitted to the hospital directly from the emergency department with a diagnosis of "rule out ectopic pregnancy" during the same time interval was identified. Nine of the directly admitted patients were found to have ectopic pregnancies. A statistically greater proportion of the directly admitted patients had a hematocrit less than 35% and a positive urine (tube) pregnancy test than that found for the study group. Five of the comparison group patients were noted to have a systolic blood pressure of less than or equal to 80 mm Hg. The beta HCG was found to be an essential tool in the evaluation of potential ectopic pregnancy in patients with minimal symptomatology.
The concept of treating presumed streptococcal pharyngitis prior to obtaining throat culture results remains controversial. We review the rationale for early treatment and the predictive ability of current techniques for rapidly estimating the probability of streptococcal pharyngitis. Decision analysis is combined with clinical and microscopic predictive tests to provide an approach for early treatment of presumed streptococcal pharyngitis. Our unified approach supports the treatment of presumed streptococcal pharyngitis prior to obtaining culture results when specific clinical or microscopic criteria are met.
We evaluated the efficacy of constant intravenous (IV) phenytoin infusion. Thirty-eight patients were evaluated prospectively for complications of continuous-infusion phenytoin loading. A total dose of 18 mg/kg was administered as a solution of 500 mg phenytoin in 50 mL normal saline using a constant infusion pump. The initial delivery rate was 40 mg/min. Cardiac rhythm was monitored by telemetry, and rhythm strips and vital signs were obtained every 15 minutes during infusion. Therapeutic phenytoin blood levels (greater than 10 micrograms/mL) were achieved in 37 patients (97%). Infusion was discontinued in one patient because of IV site irritation shortly after initiation of the infusion. Phenytoin levels in the toxic range were seen immediately postinfusion in 22 patients and in the four-hour postinfusion samples of 16 patients. Thirteen of 18 levels drawn 12 to 24 hours after infusion were therapeutic. Phenytoin levels greater than 20 micrograms/mL were tolerated without significant change in rhythm, QRS interval, or QT interval. A small statistically significant (P less than .05) decrease in systolic and mean arterial pressure was noted during the infusion. Complications included burning at the IV infusion site in four patients; the discomfort was relieved in three cases by reducing the rate of infusion to 20 mg/min. Seizures occurred in two patients during the infusion, requiring the additional use of diazepam or phenobarbital. Administration of a loading phenytoin dose by constant IV infusion is an effective means for achieving therapeutic levels quickly.
Transthoracic cardiac pacing historically has been relegated to the role of the technique of last resort in treating cardiac arrest. Recent studies have shown that this technique has a high rate of successful electrical capture, but often without mechanical activity. Survival rates have been shown to be dismal when the technique is used late in cardiac arrest. Results of several recent studies of patients paced by the transcutaneous technique have suggested that electrical capture can often be rapidly obtained in asystolic or pulseless bradycardic patients. Even though electrical capture can occur late in a cardiac arrest, the development of mechanical activity with survival is rare. Survivors generally have been treated early in their arrest and have had hemodynamically ineffective bradycardias. These findings suggest that rapid initiation of transcutaneous pacing in patients with Stokes-Adams attacks, increasing heart block associated with myocardial ischemia, postdefibrillation asystole, or pulseless bradycardia may improve survival. However, victims of a prolonged cardiac arrest whose myocardium has irreversibly ceased to function mechanically are unlikely to benefit from any pacing technique.
Recent studies of thoracic pressure changes during external cardiopulmonary resuscitation (CPR) suggest that there may be a significant difference in the rate of delivery of intravenous drugs when they are administered through the extrathoracic inferior vena cava (IVC) rather than the intrathoracic superior vena cava (SVC). Comparison of delivery of a radionuclide given using superior and inferior vena caval access sites was made during normal blood flow and during CPR. Mean times from injection to peak emission count in each ventricle were determined. There were no significant differences between mean peak times for SVC or IVC routes during normal flow or CPR. When peak times were corrected for variations in cardiac output, there were no significant differences between IVC and SVC peak times during normal flow. During CPR, however, mean left ventricular peak time, when corrected for cardiac output, was significantly shorter (P less than .05) when the SVC route was used. The mean time for the counts to reach half the ventricular peak was statistically shorter (P less than .05) in both ventricles with the SVC route during the low flow of CPR. This suggests that during CPR, increased drug dispersion may occur when drugs are infused by the IVC route and thus may modify the anticipated effect of the drug bolus. These results suggest that during CPR, both the cardiac output and the choice of venous access are important variables for drug delivery.
We examined the effect of an inflated pneumatic antishock garment (PASG) on simulated drug delivery through a distally placed venous catheter, during both normal flow and cardiopulmonary resuscitation (CPR). A PASG device was applied to anesthetized mongrel dogs and was inflated to 60 mm Hg. A small bolus of radionuclide was injected through an intravenous catheter placed distal to the PASG. Emission counts were made over both ventricles during conditions of normal flow and then during CPR following cardiac arrest. Mean times from injection to peak counts were determined. A control group of animals with central venous catheters but no PASG was studied similarly. There were no clinically appreciable differences between groups during normal flow. During CPR the PASG animals showed a mean delay of 90 seconds to the left ventricle peak. This difference was not statistically significant. We conclude that, in this canine model, acceptable delivery of drugs can be obtained by venous infusion into a limb with a PASG inflated.
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Transcutaneous cardiac pacing holds promise as the initial cardiac pacing technique for emergency patients. Determination of the extent of myocardial injury associated with the use of commercial transcutaneous pacemaker devices has been limited. This study was undertaken to document electrocardiographic, enzymatic, and histologic changes following transcutaneous pacing. Ten mongrel dogs were paced with a transcutaneous cardiac pacemaker for 30 minutes. Electrical pulses of 100 mA lasting 20 ms each were delivered at a rate of 80/min via cutaneous electrodes on the anterior and posterior thorax. Myocardial damage was assessed by serial electrocardiograms (ECGs), serial creatine kinase (CK) determinations with myocardial band (MB) fractionation, and gross and microscopic pathologic examination. Double blind reading of the ECGs showed no significant changes after pacing. CK levels peaked an average of 78 units over baseline levels at 4 hours; however, there was no rise in the CK MB fraction. Pathologic examination revealed micro-infarcts adjacent to intramural vessels in 5 animals, but no clinically significant myocardial injury in the 10 dogs. The absence of enzymatic, cardiographic, and clinically significant pathologic findings was statistically significant (P less than .05). Transcutaneous pacing at low currents and for short periods appears to be a safe technique. This pacing technique deserves further evaluation, and may hold promise as a clinical tool during resuscitation.
Prehospital blunt trauma care in one community was characterized retrospectively by the use of clinical and anatomic indices of injury severity. The predicted number of deaths derived from anatomic indices (Anatomic Index and Injury Severity Score) for patients found alive at the scene was statistically greater than observed. The predicted number of deaths derived from the clinical indices of injury severity (Trauma Index and Trauma Score) was not statistically different than observed. Paramedics recognized all patients with low clinical scores (Trauma Score less than or equal to 13). All such patients received an intravenous attempt and were taken to the hospital by the paramedics rather than by commercial ambulance as was the paramedics' option. Survival correlated with the absence of clinical deterioration during the prehospital phase.
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One hundred fifty-seven patients between the ages of 15 and 65 were evaluated for ankle injury. Patients without fractures were assigned to one of two treatment groups. Patients in the plaster splint group were non-weight-bearing. Patients in the early mobilization group used an elastic bandage and were permitted to begin partial weight bearing as soon as tolerated while using crutches. The talar tilt (stress) test was not found to be a useful routine radiographic study. Of the patients with follow-up, no significant benefit was obtained from the plaster splint. Aside from a previous ankle injury adversely affecting long-term ankle function, no historical or physical factor was useful in predicting either short- or long-term disability.
Sixty-one sledding accidents presenting to two Philadelphia-area hospitals during a three-week period were reviewed. The majority of injuries were contusions and abrasions. Eight patients required hospitalization: four had abdominal injury. One patient with multiple trauma was pronounced dead on arrival. The physics of sledding and possible mechanisms of injury are discussed.
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The heavy use of chlorine gas in industry and water purification poses the constant threat of mass gas exposure. In a recent experience with a chlorine gas disaster involving over 100 patients, 64, including six subsequently requiring admission, were treated in the main emergency unit facility. The remainder were triaged to a safe area away from the emergency unit with instructions for symptomatic treatment. Injuries were limited to four organ systems: pulmonary, gastrointestinal, ophthalmic, and cutaneous. Current treatment methods are compared with those in the literature and a protocol for management provided.
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