Biomedical subjects

R F Kopel

Publications and source records attributed to R F Kopel.

6 recordsLinked to original sources

PubMed1993

Optimal atrioventricular (AV) pacing interval during temporary AV sequential pacing after cardiac surgery.

Temporary dual chamber atrioventricular (AV) pacing is often used to increase cardiac output (CO) after cardiac surgery. The AV interval was varied to investigate the effect on CO in 13 patients. CO was computed from the Fick principle using mixed venous oxygen saturation (SvO2), arterial oxygen saturation (SaO2), hemoglobin, and oxygen consumption (VO2). AV intervals were varied randomly from 0.025 to 0.300 seconds in 0.025-second increments. The effect on CO from increasing the AV interval was dependent on the control CO. In all patients, as the AV interval was increased from 0.025 to 0.100 seconds, CO progressively increased. In most patients, the highest (optimal) CO occurred with AV pacing and averaged 300 mL/min greater than with atrial (A) pacing alone (P < .0001). In patients with a high initial CO (> 6.0 L/min), CO peaked and averaged 0.5 L/min more than with A pacing. CO was maximal for each of these patients at a unique AV interval between 0.100 and 0.225 seconds, and at intervals greater than 0.225 seconds CO decreased (P < .01). In patients with intermediate CO (4-6 L/min) at AV intervals greater than 0.100 seconds, a plateau in CO was reached. No consistent pattern was seen in patients with low initial CO (< 4.0 L/min). Maximal CO may be achieved by optimizing the AV interval in patients following cardiac surgery. The optimal AV interval is between 0.100 and 0.225 seconds and is different for each patient. Continuous SvO2 monitoring allows rapid evaluation of CO changes and optimization of the AV pacing interval.

Atrioventricular Node↗

PubMed1993

A case-control study of patients readmitted to the intensive care unit.

OBJECTIVE: To determine characteristics of patients requiring readmission to an intensive care unit (ICU). DESIGN: Retrospective case-control chart review. SETTING: Adult patients in an 8-bed medical and 16-bed surgical ICU in a 650-bed university teaching hospital during an 18-month period. INTERVENTIONS: None. METHODS: Each patient readmitted to either ICU was compared to a single control patient matched for age, sex, unit, and diagnosis. A total of 117 variables were obtained from chart review. The last value for each variable before ICU discharge was used. Chi-square analysis, linear regression factor analysis, correlation, and Student's t-test were used to identify significant factors predicting the patient's return to an ICU. Descriptive statistics were used to describe various subgroups. RESULTS: Mortality rate was 41.5% in the 82 readmitted patients (comprising 4.6% of the total ICU admissions) and only 7.3% in the controls. Mean (+/- SD) hospital length of stay was 47.8 +/- 42.0 days in the study group and 20.8 +/- 14.2 days (p < .0009) in the controls. Initial ICU length of stay was 8.3 +/- 16.1 days in the readmitted group and 4.0 +/- 5.0 days (p = .02) in the controls. Variables that predicted readmission to the ICU were: increased respiratory rate (24.2 vs. 20 breaths/min, p < .002), lower hematocrit value (31.9% vs. 34.4%, p = .01), positive fluid balance (p < .03), and positive blood cultures (six in the readmitted group, none in the controls, p = .002). More than 30% of readmissions were for a recurrence or worsening of the original problem. Fifty-four percent of the patients were readmitted with pulmonary failure. Mortality rate in both groups was related to advanced age, Acute Physiology and Chronic Health Evaluation (APACHE II) scores at ICU discharge, and increased blood urea nitrogen concentrations. Mortality rate in the control group, but not in the readmitted group, correlated with the level of consciousness, serum creatinine concentration, and use of hemodialysis. CONCLUSIONS: Readmission to an ICU carries a risk of high mortality rate and increased length of stay and may represent premature discharge in at least 30% of patients. Pulmonary failure is the immediate cause of readmission in more than half of the readmitted patients. Increased respiratory rate correlates with ICU readmission. Intermediate care areas for patients with poor pulmonary function may help to avoid readmission to an ICU, prevent death, and conserve hospital resources.

Case-Control Studies↗

PubMed1990

Hemodynamic and metabolic effects of dobutamine in 18 patients after open heart surgery.

Low cardiac output syndrome frequently follows cardiopulmonary bypass (CPB) surgery. In the present study, we used dobutamine to increase cardiac index (CI) and oxygen delivery (DO2) in 18 patients after open heart surgery. Using increasing doses of dobutamine up to 10 micrograms/kg.min-1, we observed statistically significant (p less than .01) increases in mean CI (2.50 +/- 0.10 to 3.56 +/- 0.18 L/min.m2) and in mean heart rate (HR) (83 +/- 3 to 105 +/- 3 beat/min). Mean systemic vascular resistance index decreased significantly (p less than .01) in all patients (2271 +/- 101 to 1648 +/- 83 dyne.sec/cm5.m2). Pulmonary vascular resistance index did not change in the ten coronary artery bypass graft patients, but decreased significantly (p less than .01) in the eight valve replacement patients (561 +/- 98 to 421 +/- 79 dyne.sec/cm5.m2). Mean DO2 increased in all patients, although there was no concomitant increase in oxygen consumption (VO2) in four patients. We observed a significant (p less than .01) increase in mean VO2 in the remaining 14 patients (110 +/- 6 to 148 +/- 12 ml/min.m2), in spite of significant decreases in PaO2 and increases in right-to-left intrapulmonary shunting. Although increases in HR and ventricular arrhythmias may limit its use, dobutamine increases CI and DO2 in patients after CPB. In the present study, dobutamine's varying metabolic effect exemplifies the need for close monitoring of hemodynamic and metabolic variables when using vasoactive drugs in the postoperative period.

Cardiac Output, Low↗

PubMed1989

Efficacy of an attachable subcutaneous cuff for the prevention of intravascular catheter-related infection. A randomized, controlled trial.

We performed a randomized controlled trial of an attachable subcutaneous cuff for the prevention of central vascular catheter-related infection among patients receiving intensive care. Catheters were placed percutaneously into new sites with or without a cuff and were dressed with polyantibiotic ointment containing polymyxin, neomycin, and bacitracin. Microbial colonization developed in 34.5% of 29 control and 7.7% of 26 cuffed catheters. Catheter-related bloodstream infection occurred with 13.8% of control vs 0% of cuffed catheters. The cuff was not associated with adverse effects. An unexpectedly large proportion (75%) of catheter infections were due to Candida albicans. This may have been due, in part, to the use of polyantibiotic ointment, as suggested by a pooled analysis of previous trials that demonstrated increased Candida colonization of catheters with the ointment, which is not fungicidal. These data suggest that the cuff can reduce the incidence of catheter-related infection among high-risk patients receiving catheter site care with an antibacterial ointment.

Adult↗

PubMed1989

Pulmonary artery catheter deterioration during hydrochloric acid infusion for the treatment of metabolic alkalosis.

Hydrochloric acid (HCl) infusions for the correction of metabolic alkalosis have been used for 20 yr. In the critical care setting, HCl is usually infused through a central venous or pulmonary artery (PA) catheter. In two patients receiving HCl infusions through a PA catheter, we observed and examined solid yellow particulate material in the aspirating syringe while testing the proximal lumen for patiency. We carried out in vitro investigation infusing PA catheters with 0.1, 0.2, 0.3, and 0.4 normal HCl at 20 degrees, 38 degrees, and 42 degrees C for 24 and 48 h. Although frank catheter deterioration could not be documented, the surface and interior of those catheters infused with greater than 0.1 normal HCl changed texture, indicating a change in catheter composition. Exceeding a concentration of 0.1 normal is not recommended when HCl is infused through PA catheters.

Alkalosis↗

PubMed1977

Death on every weekend.

This essay is a personal account of situations experienced by a medical technician in a large emergency room. It includes examples of stressful situations that daily confront medical personnel and the inability of medical institutions to aid them in understanding and coping with death and.dying. Stemming from these stressful situations, the paper illustrates the importance of the need for medical institutions to pay direct attention to the stressful topic of death itself if the medical personnel are to work efficiently in an environment where death and dying are everyday occurrences. Although some institutions do offer in-service sessions to nurses, these services are far and few between. But the stress for all medical personnel remains high, and there remains an unfulfilled need to teach effective thanatological techniques to all medical personnel.

Adaptation, Psychological↗