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Biomedical subjects

D Zimmerman

Publications and source records attributed to D Zimmerman.

At least 73 records · Page 4Linked to original sources
PubMed1994

Automated precision current delivery: an alternative method for cardiac defibrillation.

Substantial evidence suggests that the current associated with the discharge is a more precise predictor of defibrillation success than is the total energy of the discharge. However, virtually all commercially available defibrillators are calibrated in terms of energy. This article describes an alternative type of experimental defibrillator, which provides a precisely controlled current throughout the discharge waveform, independent of the load presented to the discharge electrodes (or "paddles"). The discharge current waveform is designed to have the classical critically damped sinusoid waveform, identical to that of the traditional energy-based defibrillator when it is properly matched with its ideal load (the heart/thorax combination). The techniques used to obtain a controlled current discharge are discussed in addition to special operational features.

Automation↗
PubMed1994

Pituitary adenomas in childhood and adolescence.

A clinicopathological study of 56 pediatric patients with non-ACTH-secreting pituitary adenomas removed by a transsphenoidal neurosurgical approach was undertaken to better define the clinical presentation, to assess demographic factors, to determine the immunohistochemical staining characteristics of the tumors, and to evaluate the outcome of transsphenoidal surgical treatment and other adjuvant therapies. A separate analysis of prolactinoma patients was performed. All tumors were confirmed histologically and immunophenotyped for pituitary hormones. Forty-one patients had tumors that stained for PRL alone, eight patients had tumors that stained for PRL and GH, six patients had plurihormonal adenomas, and one patient had a tumor that stained for glycoprotein hormones. No tumors contained GH alone. Macroadenomas exceeded microadenomas (1.4:1). There were no male patients with microadenomas of any type. Females outnumbered males (3.3:1). Patients presented most frequently with headache, menstrual dysfunction (in females), galactorrhea, and hypopituitarism. All but one of the patients with hypopituitarism at presentation had macroadenomas. Tumor staining characteristics did not always correlate well with clinical status, especially with regard to GH-containing tumors. Pediatric pituitary tumors did not appear to be more invasive or more aggressive than adult pituitary tumors, contrary to some previous reports. The patients with microadenomas had a 70% operative cure rate and a 65% long term cure rate; the recurrence rate for microadenoma patients was 25%. Macroadenoma patients had a 33% operative cure rate, a 55% long term cure rate, and a recurrence rate of 33%. Thus, microadenoma and macroadenoma patients had similar long term cure rates, but macroadenoma patients required more aggressive adjuvant therapy (second surgery, radiation, or bromocriptine) and had higher rates of hypopituitarism (52% of macroadenoma patients vs. 0% of microadenoma patients required long term hormone replacement).

Adenoma↗
PubMed1994

Cushing's disease in children.

As with adults, the diagnosis of Cushing's disease in childhood can be difficult. The clinical presentation in children is distinctive in terms of the effects on growth and pubertal development. The biochemical diagnosis can usually be made with standard dexamethasone suppression testing, similar to such testing in adults. The clinical course of Cushing's disease in children tends to be more aggressive than in adults, as evidenced by higher rates of Nelson's syndrome after bilateral adrenalectomy and higher rates of recurrence after removal of corticotrope adenomas. TSS is well tolerated in children and has fewer side effects than other modalities. Currently, pituitary irradiation is best reserved as adjunctive therapy. Newer stereotactic computer assisted linear accelerator techniques (e.g., proton knife) may provide increased effectiveness with fewer side effects and be particularly useful in childhood Cushing's disease. Appropriate treatment of children with Cushing's disease can be compatible with satisfactory psychosocial adjustment and fertility in adulthood.

Adolescent↗
PubMed1993

Transepicardial defibrillation dose response: current versus energy.

In pentobarbital-anesthetized dogs, we compared the relative efficacy of current versus energy in applying the dose response method in transcardiac defibrillation. Damped sinusoidal shocks via epicardial patches were administered by a custom defibrillator permitting precise current delivery. Following the establishment of an initial estimated defibrillation threshold for energy and current, the dose response method was performed with regard to either energy defibrillation threshold (group E, n = 8) or current defibrillation threshold (group C, n = 8). Two sequential sets (I, II) of shocks (21 shocks each) were delivered in random order at each of seven doses: 0.55, 0.70, 0.85, 1.00, 1.15, 1.30, and 1.45 x defibrillation threshold. Data were subjected to nonlinear logistic regression analysis. There were no significant differences between sets I and II in either groups E or C for resistance or for raw and normalized values associated with 50% and 80% success expressed as energy, current, or voltage. Correlation coefficients (r) associated with nonlinear logistic regression analysis were significantly different for normalized current and energy for group E (0.70 +/- 11 and 0.71 +/- 12) compared to group C (0.86 +/- 0.60 and 0.88 +/- 0.06). The difference, however, could be explained by a significantly narrower range of normalized current values tested in group E (0.79 to 1.31) versus group C (0.54 to 1.46). Thus, when resistance does not change, transcardiac current offers limited advantage over energy when applying a dose response method. The efficacy of nonlinear logistic regression analysis depends upon an adequate dose range.

Animals↗
PubMed1993

Ibutilide: enhanced defibrillation via plateau sodium current activation.

Reductions in current and energy requirements for defibrillation have previously been ascribed to type III antiarrhythmic agents that block outward potassium conductance. This study investigated the effect on defibrillation of ibutilide, a type III antiarrhythmic agent that prolongs action potential duration by activating the sodium component of the plateau inward current. Pentobarbital-anesthetized dogs were subjected to serial episodes of ventricular fibrillation lasting 10 s. In protocol I, current and energy defibrillation requirements were determined via an interactive approach after bolus injections of saline placebo and ibutilide (0.1 mg/kg i.v.). In protocol II, a current dose-response method was utilized in which four shocks each at current doses of 0.7, 0.8, 0.9, and 1.0 x an estimated defibrillation threshold were administered before and after ibutilide (0.075 mg/kg bolus; 0.00125 mg.kg-1 x min-1 i.v.). In protocol I, current and energy values associated with defibrillation measured 10.9 +/- 4.5 A and 16.0 +/- 11.9 J for ibutilide compared with 14.1 +/- 5.6 A and 27.7 +/- 17.7 J for placebo, respectively (n = 9, P < 0.005). In protocol II, ibutilide significantly shifted the current doses associated with 50% successful defibrillation from 14.8 +/- 3.7 to 8.9 +/- 2.0 A (n = 6, P < 0.05). Eight of 15 animals given ibutilide exhibited one or more episodes of spontaneous defibrillation. Ibutilide significantly (P < 0.05) increased ventricular effective refractory period (+23.4%), and both preventricular fibrillation and postdefibrillation monophasic action potential duration at 90% repolarization (+21.7% and +23.3%, n = 9, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1993

Congenital gigantism due to growth hormone-releasing hormone excess and pituitary hyperplasia with adenomatous transformation.

The cause of gigantism in most patients is a GH-secreting pituitary tumor. In this report, a case of congenital gigantism due to probable central hypersection of GH-releasing hormone (GHRH) is described. Normal at birth (4.4 kg; 53 cm), our 7-yr-old male patient grew progressively thereafter to attain a height of 182 cm and a weight of 99.4 kg at the time of our evaluation. The markedly increased baseline plasma levels of GH (730 micrograms/L) did not suppress during a standard 3-h oral glucose tolerance test, but did increase 54% after iv infusion of GHRH. Baseline plasma levels of insulin-like growth factor-I, PRL, and immunoreactive GHRH were also markedly increased. Computed imaging of the head showed a large, partially cystic sellar and suprasellar mass. Extensive imaging studies did not localize a potential source of GHRH. Preoperative treatment with octreotide and bromocriptine for 4 months resulted in a 25% reduction of suprasellar tissue mass. The pituitary tissue removed at transsphenoidal and transfrontal operations showed massive somatotroph, lactotroph, and mammosomatotroph hyperplasia. Areas of GH- and PRL-secreting cell adenomatous transformation were also evident. No histological or immunohistochemical evidence of a pituitary source of GHRH was found. The peripheral plasma immunoreactive GHRH concentration remained unaffected by pharmacological and surgical interventions. We suspect that a congenital hypothalamic regulatory defect may be responsible for the GHRH excess in this case.

Adenoma↗
PubMed1993

Healthcare reform adds complexities for today's CFO.

The profile of the typical senior financial executive in a hospital or corporate healthcare setting has changed little over the past two years. A November 1992 survey of CFOs by HFMA and Zimmerman & Associates, Inc., which updates a similar survey conducted in 1990, showed that the typical healthcare CFO is an extremely busy 41-year-old male with a postgraduate education who has held the position of CFO for six years. Survey findings also reveal that the CFO title is the predominant title for senior financial executives in healthcare facilities. For those receiving incentive compensation, the average compensation in 1992 was 11.7 percent of base salary. Within the context of career advancement, the CFO is most interested in learning more about healthcare reform; declining operating margins was seen as the CFO's most significant career challenge.

Adult↗
PubMed1993

Patient accounts managers prepare for change.

Automated data processing and electronic data interchange have become necessary and increasingly vital aspects of the processes of admission, registration, billing, and collection. A recent survey of patient accounts managers found they feel they may need to improve their technical skills to meet future challenges.

Data Collection↗
PubMed1992

Radiation therapy for diabetes insipidus caused by Langerhans cell histiocytosis.

Hypothalamic-pituitary radiation therapy has been the standard treatment for the diabetes insipidus of Langerhans cell histiocytosis. The goal of this study was to assess the role of radiation therapy in Langerhans cell histiocytosis-associated diabetes insipidus and to compare the results with nonirradiated controls. Forty-seven patients with pathologically confirmed Langerhans cell histiocytosis were diagnosed with diabetes insipidus between 1950 and 1989 and were treated at the Mayo Clinic. These patients were divided into two groups on the basis of treatment for the diabetes insipidus: The first group (radiation group) included 30 patients (28 of whom were evaluable for response) who received hypothalamic-pituitary radiation therapy, and the second group (control group) included 17 patients who did not. A partial response to treatment was defined as a reduction in vasopressin dosage or improvement in computed tomography (CT) or magnetic resonance imaging (MRI). A complete response was defined as no further need for vasopressin therapy or normalization of CT or MRI. End points analyzed included treatment response, patient characteristics, morbidity, dose-response relationship, and survival. Patient characteristics of the two groups were similar except for age and lung involvement, both of which were significantly less in the radiation group. Thirty-six percent of patients (10 of 28) in the radiation group responded to hypothalamic-pituitary radiation therapy (22% complete response and 14% partial response), whereas none in the control group responded. Five of the six complete responders were irradiated within 14 days of the diagnosis of diabetes insipidus. The mean dose used in the responding and nonresponding patients was 11.2 and 10 Gy, respectively. Three of five patients (60%) treated with more than 15 Gy responded compared to seven of 23 (30%) treated with less than 15 Gy. Eight of the 10 responders (80%), compared to 16 of 35 nonresponders (46%), were female. Only one in 20 patients with concomitant lung histiocytosis responded. Complications of therapy may include insufficiency in other hypothalamic-pituitary axes in the treated patients. Actuarial survivals at 5, 10, 20, and 40 years for the entire group were 80%, 78%, 75%, and 65%, respectively, with a median follow-up in living patients of 14.7 years.

Adolescent↗
PubMed1992

Tibia vara in a patient with Bardet-Biedl syndrome.

The Bardet-Biedl syndrome is characterized by polydactyly, hypogonadism, obesity, mental retardation, and retinitis pigmentosa. Several other skeletal findings include hip dysplasia, short stature, and skull deformities. The patient described in this report has the classic findings of Bardet-Biedl syndrome in conjunction with tibia vara and irregular physes of the lower extremities.

Abnormalities, Multiple↗
PubMed1991

Medicaid spenddown among nursing home residents in Wisconsin.

We examined Medicaid spenddown among nursing home residents from 72 facilities in Wisconsin during 1988. Results indicate that only a small proportion (12%) of discharges from these facilities had spent down to Medicaid eligibility. This represents about one-fourth (23%) of persons who had been admitted private pay. Moreover, we estimated that over 40% of those who spent down to Medicaid did so within 6 months, 58% spent down within a year, and 76% spent down within 2 years. Even though a relatively small percentage of residents spent down, this group had very long stays (median stay greater than 3 years) and thus contributed quite heavily to nursing home days.

Aged↗
PubMed1991

Reconsiderations of the routine and preferential use of lidocaine in the emergent treatment of ventricular arrhythmias.

OBJECTIVE: Despite a history of widespread use, the utility of lidocaine as an antiarrhythmic and antifibrillatory agent is questionable. The objective of this article is to examine the theoretical basis for the use of lidocaine in light of recent experimental and clinical data. This article reviews the effects of lidocaine on: a) ventricular arrhythmias under ischemic and nonischemic conditions; b) the energy and current requirements for defibrillation; and c) the propensity for asystole during cardiac arrest. DESIGN: A contemporary review of the literature. FINDINGS: There appears to be a theoretical basis for the use of lidocaine in treating ventricular arrhythmias secondary to acute ischemia largely based on voltage- and pH-dependent binding and inactivation of sodium channels by lidocaine under ischemic conditions. However, clinical and experimental data failed to establish enhanced survival following prophylactic treatment for acute ischemic events or when treatment is administered during cardiac arrest. Moreover, there are no data supporting the use of lidocaine in treating sustained and life-threatening ventricular arrhythmias in the absence of acute ischemia. Experimental data demonstrate that lidocaine can reduce countershock efficacy, i.e., increase the current and energy requirements for defibrillation. Experimental and clinical data suggest that the administration of lidocaine increases the propensity for asystole during cardiac arrest. CONCLUSIONS: While lidocaine may possess an antifibrillatory effect under experimental conditions, the clinical relevance of such an effect is questionable. If cardiac arrest occurs, lidocaine has limited utility and may be deleterious secondary to diminished countershock efficacy or lidocaine-induced asystole. Reconsideration of the use of lidocaine should be included in future guidelines for management of cardiac arrest.

Arrhythmias, Cardiac↗
PubMed1991

Limitations of the countershock dose response: a study of transthoracic current.

Dose response assessment of countershock efficacy has been widely determined with respect to energy but not current. The purpose of this study was to examine the utility of the dose response method in a current-based model of transthoracic defibrillation (pentobarbital anesthetized dogs, n = 8). Ventricular fibrillation induction lasting 15 seconds was separated by 5-minute intervals. Current defibrillation threshold (DFT; the lowest current that successfully defibrillated) was determined by decreasing current on successive trials. Energy DFT equaled the energy value of the corresponding current DFT. Subsequent data were expressed in normalized terms with each DFT assigned a normalized value of 1.00. Three shocks were delivered in random order at each of seven normalized current nodes (total of 21 shocks): 0.55, 0.70, 0.85, 1.00, 1.15, 1.30, and 2.00 x DFT (early testing). Randomization was repeated, and a second set of 21 trials were performed (late testing). Composite plots were made relating normalized current and energy to the percent successful defibrillation. The dose response expressed in normalized energy demonstrated an overall shift to the left compared to current. The difference was significant at every node value below the estimated DFT. Ninety percent of successful trials with respect to current and energy occurred at or above 0.85 DFT and 0.55 DFT, respectively. Significant changes in impedance occurred between early testing (60 +/- 6 ohms) and late testing (47 +/- 5 ohms), n = 8, mean +/- SD. Current, compared to energy, is a more accurate parameter in the dose response assessment of transthoracic defibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗