Biomedical subjects

D E Schaber

Publications and source records attributed to D E Schaber.

4 recordsLinked to original sources

PubMed1997

Derivation of a defibrillator implant criterion based on probability of successful defibrillation.

Common criteria for implant of a cardioverter defibrillator include verification of a 2:1 energy safety margin or a fixed safety margin of 10 joules. These criteria have been established empirically. We present a statistically model based on defibrillation efficacy curves which may be used to establish a criterion which would meet a predetermined target. As an example, an implant criterion is derived based on a goal of 1-year sudden cardiac death survival of at least 99% by selecting an expected first-shock efficacy to meet that target. Logistic regression was performed on data from over 1,500 defibrillator implants including successful epicardial and transvenous electrode system implants as well as data from unsuccessful implants. A random sample from these curves was used to generate a representative sample of 1,000 potential implant candidates. By assuming successful defibrillation using a series of shocks at specified energies, i.e., choosing an implant criterion, the probability of successful defibrillation of the patient by a single shock at a predetermined maximum output can be established. Independent data are used to validate the model's accuracy in predicting defibrillation efficacy within the derived example.

Clinical Protocols↗

PubMed1987

Apparent inconsistent theophylline absorption from sustained release capsules.

Sustained release theophylline products can improve compliance and symptom control in children with asthma. This study examines theophylline serum concentration monitoring in pediatric patients. Fifteen children with documented asthma were randomized to receive either Slo-bid Gyrocaps or Theo-dur Sprinkle for 1 month, and then crossed over to the other product. On the last day of each study period, theophylline serum concentrations were obtained prior to the morning dose and 4 hours later. In two patients receiving Theo-dur Sprinkle and six with Slo-bid Gyrocaps, the 4-hour serum concentration was lower than the pre-dose concentration. The change between the pre-dose and post-dose serum concentrations for Theo-dur Sprinkle ranged from a decrease of 2.8 mg/L to an increase of 4.9 mg/L, and, for Slo-bid Gyrocaps, from a decrease of 4.6 mg/L to an increase of 10.5 mg/L. The inconsistent theophylline absorption with each product makes dosage adjustment difficult.

Absorption↗

PubMed1985

Intravenous KCl supplementation in pediatric cardiac surgical patients.

A total of 31 pediatric cardiac patients (mean age 19 1/2 months) who required surgery for repair of various congenital heart defects were prospectively studied in the postoperative period to determine potassium (K) dose-response characteristics. All patients received supplementary K when the serum K was less than 4.0 meq/liter. A total of 100 administrations of intravenous potassium chloride (KCl) were evaluated. KCl, 0.5 meq/kg, was infused over 2 h by syringe pump. This infusion was repeated as necessary to achieve a serum K greater than or equal to 4.0 meq/liter. The KCl was administered in addition to the K in the patients' maintenance solution. Blood samples for serum K determination were collected 15-30 min before and after the KCl infusion. The mean K dose administered was 0.72 +/- 0.23 meq/kg. This produced a mean rise in serum K of 0.61 +/- 0.48 meq/liter. Of 100 administrations, 11 resulted in no change or a decrease in serum K. Four of 100 administrations resulted in serum K greater than 5.0 meq/liter. Intravenous KCl supplementation in a dose of 0.5 meq/kg administered over 2 h is safe and effective for pediatric postoperative cardiac patients. Serum K should be measured to monitor therapy, due to variable response.

Adolescent↗

PubMedDate not supplied

Nitroglycerin adsorption to a combination polyvinyl chloride, polyethylene intravenous administration set.

Loss of nitroglycerin (NTG) from intravenous solutions to intravenous bags and administration sets has been well documented. This study was designed to examine a commercially available low adsorption administration set that was compatible with a volumetric infusion pump. A solution of NTG 100 micrograms/ml in dextrose 5% in glass bottles was used. Six study administration sets were tested. The infusion sets were connected to the NTG-containing glass bottles, filled as rapidly as possible, placed in the infusion pump, and set at the appropriate rate. Effluent was collected for NTG assay initially, and at 20 and 40 minutes, and 1, 1.5, 2, 3, 6, and 24 hours. The effects of flow rate were studied at 0.2 and 1.0 ml/min. The tubing performed similarly to other polyvinyl chloride (PVC)-containing sets at 0.2 ml/min and similar to non-PVC sets at 1.0 ml/min. The effect of an initial flush with 20-100 ml of 100 micrograms/ml NTG was also examined. An initial flush of 20 ml of 100 micrograms/ml NTG solution was found to enhance delivery of NTG immediately. NTG aliquots were stored frozen in glass vials prior to assay by high performance liquid chromatography.

Adsorption↗