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Biomedical subjects

C Case

Publications and source records attributed to C Case.

At least 37 records · Page 2Linked to original sources
PubMed1995

The learning curve for radiofrequency ablation of tachyarrhythmias in pediatric patients. Participating members of the Pediatric Electrophysiology Society.

The results of radiofrequency ablation for treatment of supraventricular tachyarrhythmias have been reported to improve with increasing experience; however, the precise nature of the learning curve in children is unknown. From November 1990 to October 1993, 1,546 consecutive procedures from the Pediatric Radiofrequency Ablation Registry were categorized into deciles based on number of prior pediatric procedures at the submitting institution. Negative exponential models were tested for strength of relation between volume of prior experience and 4 measures of outcome: success rate, complication rate, fluoroscopy time, and procedure time. Negative exponential curves described the experience-outcome relations well (r = 0.81 to 0.97). Learning rates were most rapid for successful ablation of left free wall accessory pathways, and slowest for right free wall pathway ablation. These models suggest that, given enough experience, procedural success rates > 90% (regardless of pathway location) and fluoroscopy and procedure times averaging < 40 minutes and 250 minutes, respectively, can be achieved in pediatric patients.

Adolescent↗
PubMed1995

The use of ultrasound in the non-invasive detection of changes in the renal circulation in response to blood loss using an animal model.

Using a continuous haemorrhage model, 8 anaesthetised swine were bled 1 ml/kg per min for 30 min. The resistance index (RI) of the main renal artery, interlobar and arcuate vessels all significantly increased. Cortical Doppler signals were lost in 4 animals at a mean arterial pressure of 26 mmHg. After reinfusion of blood and normal saline only the RI of the interlobar vessels was significantly different from baseline readings. Ultrasound demonstrated non-invasively changes in regional blood flow within the kidney in response to hypovolaemic shock.

Animals↗
PubMed1995

High dose and standard dose adrenaline do not alter survival, compared with placebo, in cardiac arrest.

This trial compared blinded 10 mg aliquots of adrenaline with placebo in 194 cardiac arrest patients treated in hospital using American Heart Association guidelines. In-hospital and out-of-hospital arrests were included. Of the 339 eligible patients a large proportion (145 (45%)) were not randomised and received open 1 mg aliquots of adrenaline. This group is also analysed. Supervising physicians gave significant preference for males, patients with no previous cardiac history and without multiple organ disease to be given open 1 mg adrenaline. Patients in asystole at the time of consideration for entry were preferentially placed in the trial group (114 (69%) vs. 170 (88%)) and patients in ventricular fibrillation were preferentially given open 1 mg adrenaline (31 (21%) vs. 24 (12%) P < 0.03). The most beneficial rhythm changes which led to survival were sinus rhythm and ventricular tachycardia. Analysis of rhythm changes resulting from the dosing showed a significant (P = 0.01) change to a beneficial rhythm with 10 mg adrenaline but not for 1 mg adrenaline or placebo. This was not reflected by an improvement in immediate survival. No significant differences in immediate survival (IS) or hospital discharge (HD) exists between open 1 mg adrenaline (IS 14 (9.7%), HD 3 (2%)) or the 10 mg adrenaline (IS 9 (9.6%), HD 0) vs. placebo (IS 7 (7%), HD 0) trial arms. Patients reaching the point of use of adrenaline have a uniformly poor immediate survival (8.8%) and hospital discharge rate (0.9%). Dosing with 10 mg or 1 mg adrenaline does not influence outcome compared with placebo.

Aged↗
PubMed1995

[Impulsive noise: PTS and anatomic correlations].

The EEH (Equal Energy Hypothesis) postulates that permanent hearing loss (PTS) produced by exposure to noise is a function of sound energy of the exposure. The validity of EEH for continuous noise exposure was confirmed by large scale demographic studies and experiments in controlled laboratory setting. However, for impulse noise, EEH may not be as valid. This study was designed to test the applicability of EEH in impulse noise exposure in chinchillas. 9 groups of chinchillas were exposed to impulse noise. The intensity of the impulses (113, 125 and 137 dB SPL) and the rate (900, 3,600 and 14,400 impulses/hour) of the 9 exposure conditions were counterbalanced so that the 9 groups received the same total energy. PTS was obtained at 0.5, 2. and 8.0 kHz, by recording the evoked potentials from a chronic electrode implanted in the inferior colliculus. The cochleas were dissected and evaluated using conventional histological surface preparations and examined through scanning electron microscopy (SEM) employing a JEOL 35 microscopy. In our experimental conditions only the 113 dB SPL exposures were consistent with EEH (PTS less than 20 dB). The 125 dB SPL peak level is a critical value in that the validity of EEH also depends on exposure duration. As duration increases, so does PTS. At a 137 dB SPL peak level, EEH is not applicable. The amount of PTS is higher than 50 dB. It slightly increases when the impulse rate per hour becomes higher. In all cases examined PTS is less at 0.5 kHz than at 2.0 or 8 kHz. In these animals excellent informations concerning the sensory cell losses and cells damage was obtained with SEM.

Animals↗
PubMed1993

Rhythm changes during resuscitation from ventricular fibrillation.

Defibrillation of patients with primary ventricular fibrillation (VF) results in a variety of rhythm changes. We analysed these changes in rhythm in 200 patients, using the American Heart Association's recommendation of two defibrillations prior to drug therapy. Sixty-three (31.5%) patients were immediate survivors with 38 (19%) being discharged from hospital alive. There was no difference between the age of immediate survivors (66.5 years, S.D. = 11.2) and non-survivors (68.3 years, S.D. = 13.7, P = 0.37). Immediate survivors were significantly more likely to be discharged alive from hospital if they were younger (70.0 years, S.D. 8.5 vs. 62.1 years, S.D. 15.8, P = 0.014). Increasing delays to the initiation of basic life support (CPR) and to defibrillation were associated with significantly less likelihood of cardioversion to sinus rhythm (P < 0.005 and P < 0.002, respectively). Those patients who stayed in VF were not more likely to be defibrillated into asystole or electro-mechanical dissociation. Seventeen percent (34) of patients were defibrillated to sinus rhythm after the first defibrillation and 14% (19) after the second, with similar hospital discharge rates (62% and 58%, respectively). Sixty percent (32) of patients in sinus rhythm, after two defibrillations, were discharged alive, compared to only 4% (6) of those patients not in sinus rhythm after two defibrillations. Our data provide new information on rhythm changes during resuscitation and supports the need for the earliest possible initiation of basic life support and defibrillation to improve survival from cardiac arrest due to ventricular fibrillation.

Age Factors↗
PubMed1992

Doppler color imaging. Obstetric and gynecologic applications.

The addition of pulsed and color Doppler has greatly added to the diagnostic potential for obstetric and gynecologic ultrasound. In addition to improved morphologic detail inherent in the use of EVUS, new information is available on perfusion and the physiologic changes associated with the menstrual cycle and early pregnancy. The absence of luteal flow strongly predicts unsuccessful pregnancy outcome in patients undergoing therapy for infertility. This introduces the possibility of more economic use of expensive treatments. Later in pregnancy, DCI aids in the efficient and accurate performance of Doppler spectral sampling and contributes to the evaluation of structural and functional abnormalities of the fetus, umbilical cord, and placenta. Applications in the evaluation of patients with suspected ectopic pregnancy, incomplete abortion, and pseudosac are welcome additions for clinical problems that currently result in many malpractice suits. Finally, the recognition of neovascular flow, especially in the ovary, raises hope for improved and earlier diagnosis of ovarian cancer.

Color↗
PubMed1991

The Health Knowledge Inventory-Alpha: a personal health knowledge test for high school seniors.

This study assessed validity and reliability of the Health Knowledge Inventory-Alpha (HKI-Alpha) in a sample of high school seniors. The HKI-Alpha, a general health knowledge test, consists of 110 multiple choice items covering 11 health content areas. All seniors attending one of four high schools completed HKI-Alpha twice, one week apart. A secondary sample of college students also was tested. Descriptive analysis revealed the test discriminated among examinees and avoided ceiling and floor effects. Test-retest reliability was .81 (n = 355). Internal consistency reliability (KR20) was .85 (n = 418). A sample of college students scored significantly higher than the high school students, demonstrating construct validity. Other estimates of content validity, criterion-related validity, and construct validity were high.

Adolescent↗
PubMed1990

Surgical management of Wolff-Parkinson-White syndrome in infants and small children.

Surgical ablation of accessory conduction pathways has rarely been reported in infants and small children with Wolff-Parkinson-White syndrome. In the interval January 1985 to September 1988, 19 infants and children aged 5 or younger have undergone surgical ablation of accessory conduction pathways because of recurrent supraventricular tachycardia. There were 12 (63%) boys and seven (37%) girls. Age ranged from 4 to 66 months (mean 33.8 months). Nine infants were less than 24 months old. Weight ranged from 5.5 to 2.16 kg (mean 13.2 kg). All 19 patients had symptoms, with duration of symptoms ranging from 3 to 63 months (mean 21 months). Accessory conduction pathways were classified preoperatively as left free wall in four (21%), right free wall in nine (47%), and posterior septal in six (32%). No multiple pathways were recognized preoperatively. Left ventricular function was abnormal in four (21%) preoperatively. Free wall pathways (n = 13) were surgically dissected and septal pathways (n = 6) were cryoablated at -70 degrees C. Mean cardiopulmonary bypass time was 60 +/- 4 minutes. Mean crossclamp time was 42 +/- 2 minutes in those undergoing surgical dissection. Mean postoperative stay was 6.4 +/- 0.2 days. There were no deaths, no significant postoperative complications, and no instance of complete heart block. All patients were considered cured at the time of discharge. At a mean follow-up of 12.7 months, 18 (94.7%) remain cured. One patient with Ebstein's anomaly and a right free wall pathway had a recurrent supraventricular tachycardia 3 months postoperatively, and repeat electrophysiologic study has shown a previously unsuspected anterior septal pathway. Ventricular function returned to normal in all four patients who had abnormal function preoperatively. Surgical ablation of accessory conduction pathways can be safely done in infants and small children with results equal to those obtained in adults.

Adolescent↗
PubMed1988

Adverse effect of early high-dose adrenaline on outcome of ventricular fibrillation.

Resuscitation for cardiac arrest was monitored over 4 years to examine the effect on survival of a change in the ventricular fibrillation (VF) protocol to include the routine early use of "high-dose" intravenous or transbronchial adrenaline. A significant reduction in the immediate survival of patients with VF was seen when the protocol was changed (22% after the change, 43% before). Prior predictors of poor response were similar in each group, except for the number of witnessed arrests, delay until cardiopulmonary resuscitation, and occurrence of endotracheal intubation, but multiple logistic regression showed the use of adrenaline to be an independent predictor of outcome. Early high-dose adrenaline was associated with a reduction in immediate survival in patients with persistent VF.

Aged↗
PubMed1976

Go to health.

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Health Education↗
PubMed1972

Antimicrobial properties of natural phenols and related compounds: obtusastyrene and dihydro-obtusastyrene.

Factors influencing the antimicrobial properties of obtusastyrene and dihydro-obtusastyrene were studied. Both of these compounds were soluble in acetone, alcohol, and olive oil. In water, they were soluble at concentrations of 34 and 53 mug/ml, respectively. The minimal inhibitory concentrations against gram-positive bacteria and yeast were below 100 mug/ml. The compounds were not effective against gram-negative bacteria at 200 mug/ml or lower concentrations. With initial populations of cells greater than 10(6)/ml, the concentrations of these compounds required to prevent growth were greater than with lower cell populations. Changing the pH of the growth medium did not decrease the effectiveness of these two compounds in the pH range of 3 through 8. Both obtusastyrene and dihydro-obtusastyrene were rapidly bactericidal to Staphylococcus aureus and Bacillus cereus at 25 mug/ml.

Alcaligenes↗
PubMedDate not supplied

Role of repeated fine-needle aspiration of thyroid nodules with benign cytologic features.

OBJECTIVE: To determine the role of repeated fine-needle aspiration (FNA) biopsy in the evaluation of thyroid nodules initially classified as benign. METHODS: We retrospectively reviewed data on 235 patients with clinically palpable thyroid nodules who underwent a repeated FNA biopsy after an initially benign diagnosis. All the nodules were evaluated and biopsies were obtained by the same endocrinologist. Cytodiagnoses were divided into four major categories: inadequate, benign, suspicious, or malignant. RESULTS: The study cohort consisted of 211 female and 24 male patients with a mean age of 47.1 years. The repeated FNA cytodiagnoses were as follows: 204 (86.8%) remained benign and 19 (8.1%), 11 (4.7%), and 1 (0.4%) became inadequate, suspicious, and malignant, respectively. All patients with benign or inadequate cytologic results on repeated FNA who underwent thyroid surgical resection had benign histologic findings (N = 23). The mean follow-up period between the initial and the last benign FNA cytodiagnosis in the 186 patients without surgical intervention was 1,078 days (2.95 years). Nine of 11 patients with suspicious cytologic results underwent a thyroid surgical procedure, which revealed a benign lesion in 7 and malignant disease in 2 (18%). The other two patients with suspicious cytologic findings had a 13-year clinical follow-up without any clinical evidence of a thyroid malignant lesion. The only patient with malignant cytologic findings on repeated FNA (a 76-year-old woman) refused surgical treatment and was lost to follow-up. CONCLUSION: Although the yield of finding a malignant lesion on repeated FNA biopsy in the follow-up of a presumably benign thyroid nodule may be low, rebiopsy reduces the rate of false-negative diagnosis from an average of 5.2% to <1.3%.

Adolescent↗