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Biomedical subjects

J Swartz

Publications and source records attributed to J Swartz.

At least 19 recordsLinked to original sources
PubMed1990

Intraoperative anaphylaxis to latex.

This case report describes intraoperative anaphylaxis occurring in a fourteen-year-old female with spina bifida in which latex surgical gloves were incriminated as the aetiologic agent. The patient was non-atopic but since eight years of age she had developed localized angioedema and urticarial skin reactions on exposure to rubber. She had previously undergone several uneventful surgical procedures. Forty-five minutes following induction of anaesthesia and during laparotomy for elective cholecystectomy she experienced sudden onset of increased airway pressure, oxygen desaturation, tachycardia, profound hypotension and erythema consistent with an anaphylactic reaction. Resuscitation with manual ventilation and oxygen, intravenous fluids and an epinephrine infusion was successful. Subsequent investigations for allergies demonstrated a strongly positive skin prick test and RAST to latex antigen, with negative results to anaesthetic agents, antibiotics and inhalant allergens. During two later operations prophylaxis consisting of diphenhydramine, ranitidine and hydrocortisone appeared to prevent further reactions. Latex should be considered as a cause of life-threatening intraoperative allergic reactions in patients with a history of rubber allergy or frequent exposure to latex products.

Adolescent↗
PubMed1990

Steroid-tipped leads versus porous platinum permanent pacemaker leads: a controlled study.

There is little data directly comparing steroid-tipped permanent pacemaker leads to otherwise state-of-the-art porous platinum leads. Eighteen patients receiving unipolar generators capable of low voltage outputs were randomized at the time of implant to receive either steroid-tipped leads or porous platinum leads. All leads were unipolar, tined, passive fixation, and placed in the right ventricular apex or atrial appendage. This study is single center. At implant, threshold pulse width was determined at 3 voltages (2.5, 1.5, and 0.8 V). Follow-up thresholds were determined at weeks 1, 2, 3, and 4, and at 3 and 6 months. There was no difference in implant thresholds or amplitudes for sensing. By 2 weeks postimplant, lower thresholds were noted for the steroid leads, and this discrepancy grew more significant with time. There was no significant postimplant rise in threshold for steroid-tipped leads. At 6 months, the average threshold pulse width for ventricular steroid leads at 0.8 V was 0.3 +/- 0.1 msec. In contrast, five patients with standard leads did not capture at maximum pulse width at 0.8 V (P less than 0.0001). There was no significant difference in the amplitude of the chronic atrial electrogram. This study shows steroid-tipped leads to offer a significant advantage in reducing thresholds early postimplant and chronically.

Aged↗
PubMed1989

Effects of age on the serum concentration of alpha 1-acid glycoprotein and the binding of lidocaine in pediatric patients.

We determined the effect of age on the serum concentration of alpha 1-acid glycoprotein (alpha 1-AGP) in venous blood from 134 subjects who ranged in age from preterm neonates to 18-year-old adolescents. The mean (+/- SD) serum concentration of alpha 1-AGP, determined by radial immunodiffusion, increased significantly with age: the concentration found in neonates was less than that found in infants which, in turn, was less than that found in older children (p less than 0.001). In addition, we determined the effect of alpha 1-AGP on the free fraction of lidocaine in four groups of infants and children who received intravenous lidocaine (1.5 mg/kg). The percentage of free lidocaine correlated inversely and linearly with the serum alpha 1-AGP concentration (r2 = 0.617; p less than 0.001). The percentage of free lidocaine in the five neonates exceeded that in the older age groups. We conclude that the serum concentration of alpha 1-AGP increases while the free fraction of lidocaine decreases from early infancy to adolescence.

Adolescent↗
PubMed1989

Mutant frequency of radiotherapy technicians appears to be associated with recent dose of ionizing radiation.

The frequency of hypoxanthine phosphoribosyl transferase (HPRT) mutants among peripheral T-lymphocytes of radiotherapy technicians primarily exposed to 60Co was measured by the T-cell cloning method. Mutant frequencies of these technicians in 1984 and 1986 were significantly higher than those of physiotherapy technicians who worked in a neighboring service, and correlated significantly with thermoluminescence dosimeter readings recorded during the 6 mo preceding mutant frequency determination. Correlations decreased when related to dose recorded over longer time intervals. HPRT mutant frequency determination in peripheral lymphocytes is a good measure of recently received biologically effective radiation dose in an occupationally exposed population.

Adult↗
PubMed1989

Advances in catheter ablation use of unipolar electrograms.

Ventricular tachycardia in man can be eliminated by relatively small lesions in the reentrant circuit. This report includes a review of available energy sources, and methods for localizing arrhythmias. Methods to assure contact and prevent perforation using low frequency electrograms are presented including the new finding of reverse ST deflection with contact. Experience with laser energy in dogs showed discrete homogenous lesions. When compared with DC shock the animals showed far less arrhythmia and the lack of far field effect greatly reduced echo abnormalities in the post shock period. Studies with radiofrequency show ability to produce localized lesions similar to the laser but with a more flexible catheter. Localization requires a correlation of techniques including pacemapping, activation maps and pacing during tachycardia. Early activation (less than -60 ms) at times 180-320 ms, with comparable pace to QRS during tachycardia with no change in morphology best localized the slow zone of the reentrant circuit. The low frequency unipolar electrogram from the tip and immediately proximal electrode revealed contact with ST deviation. The distal deviation was always greater than the proximal RV free wall and posterior basal produced depression rather than elevation of the electrogram. While the mechanism of ST reversal with contact is not understood and may relate to the type of indifferent reference used (Wilson central terminal), the ST depression reveals the same information about contact that elevation does in most areas of the heart studied in our patients.

Animals↗
PubMed1987

Retinal complications in the acquired immunodeficiency syndrome. A case report.

Increasing numbers of patients with the acquired immunodeficiency syndrome (AIDS) are being reported. In the US literature the eye complications have been well documented but because so few cases of AIDS have been reported in South Africa, the retinal complications are largely unknown to those treating these patients. The retinal complications are due to cytomegalovirus (CMV) retinitis. The patient described here developed the typical signs in both eyes. It is essential to examine the fundi of AIDS patients regularly. The presence of cotton-wool spots always precedes CMV retinitis, which leads to blindness; it is also of prognostic significance since all reported patients with CMV retinitis have died.

Acquired Immunodeficiency Syndrome↗
PubMed1987

The effect of ketamine anaesthesia on the acidotic fetal lamb.

The following study in pregnant ewes was done to examine the effects of ketamine-oxygen anaesthesia on the fetal lamb made acidotic by partial occlusion of the umbilical cord. Fifteen pregnant ewes were instrumented under general anaesthesia to allow continuous measurement of maternal and fetal mean arterial pressure and pulse rate and for withdrawal of arterial blood samples for blood gas analysis. An occlusion loop was loosely secured around the umbilical cord. Following a recovery period of 48 hours, a tracheostomy was performed on each ewe. After a control period, the umbilical occlusion loop was slowly inflated until fetal pH had decreased to 7.12-7.15. Following inflation the animals were divided into groups A and B. Group A received no anaesthesia. In Group B, the ewes received ketamine 3 mg X kg-1 intravenously and controlled ventilation with FIO2 of 1.0. After ten minutes ketamine 1 mg X kg-1 was given. In both groups radioactive microspheres were injected into the fetus at 0, 5, and 15 minutes. Ketamine anaesthesia in the pregnant ewe abolished the fetal hypertension and bradycardia produced by partial cord occlusion. All fetuses survived the 15 minutes of ketamine anaesthesia and there were no significant changes in arterial blood gases or pH. Blood flows determined by the microsphere method to the brain, heart, and kidneys were not significantly altered by ketamine. We conclude that ketamine-oxygen anaesthesia does not cause further deterioration in the acidotic fetal lamb.

Acidosis↗
PubMed1985

Spinal cord blood flow following sub-arachnoid lidocaine.

Twelve mongrel dogs were randomized into two equal groups. Cervical, thoracic and lumbosacral spinal cord and spinal dural blood flows were measured using the radioactive microsphere technique. Blood flow determinations were made prior to and 20 and 40 minutes following lumbar subarachnoid injection of: two per cent lidocaine (100 mg) or two per cent lidocaine (100 mg) with 1/25,000 epinephrine (200 micrograms). Dogs receiving subarachnoid lidocaine demonstrated a decrease in mean arterial blood pressure of 23 per cent and 14 per cent (p less than 0.05), while dogs receiving lidocaine with epinephrine had a decrease of 38 and 34 per cent (p less than 0.05) at 20 and 40 minutes respectively. Cardiac index was not significantly changed in either group. Lumbar subarachnoid lidocaine (100 mg) produced a rapid regional dural hyperemia (observed at 20 minutes postinjection) and a delayed regional spinal cord hyperemia (observed at 40 minutes postinjection) which were not observed following the addition of epinephrine (200 micrograms).

Animals↗
PubMed1985

The effects of general anaesthesia on the asphyxiated foetal lamb in utero.

The effects of anaesthetic agents, per se, on the asphyxiated foetus are difficult to quantitate clinically. Anaesthesia is often necessary in foetal distress, however, to effect a rapid delivery. To investigate the effect of general anaesthetic agents commonly used for Caesarean section we administered these agents to 18 chronically prepared pregnant ewes with asphyxiated foetuses in utero. The foetuses were asphyxiated by partial occlusion of the umbilical cord until foetal arterial pH had decreased from 7.30 to a range of 7.08-7.13. The animals were divided into three groups: Group A which received no anaesthesia and thus served as a control, Group B which received thiopentone (3 mg . kg-1) intravenously followed by 50 per cent nitrous oxide and 0.5 per cent halothane in oxygen for 15 minutes, and Group C which received thiopentone (3 mg . kg-1) followed by one per cent halothane in oxygen for 15 minutes. Foetal cerebral, myocardial, and renal blood flows were measured by injection of radioactive microspheres after production of asphyxia and after 5 and 15 minutes of anaesthesia. General anaesthesia in both groups B and C abolished the hypertension and bradycardia produced by foetal asphyxia secondary to umbilical cord occlusion. There were no significant differences between Groups B and C in foetal pH, PCO2, or PO2. Two foetuses in the nitrous oxide group died after ten minutes of anesthesia, but the aetiology of the sudden demise is unclear. We conclude that general anaesthesia abolishes the foetal response to umbilical cord occlusion and does not improve foetal oxygenation or acid-base status.

Anesthesia, General↗