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Biomedical subjects

B M Weiss

Publications and source records attributed to B M Weiss.

43 records · Page 3Linked to original sources
PubMed1989

[Reliability and limitations of pulse oximetry in corrective cyanotic heart surgery].

The aim of this study was to evaluate the agreement between arterial and pulse oximeter saturation values, especially under hypoxemic conditions, and to test the applicability of the method under routine anesthesia conditions. We studied 13 patients (12 children, 1 adult) with congenital cyanotic heart defects; 12 had a surgical correction during nonpulsatile cardiopulmonary bypass and 1 had a palliative operation. Arterial and pulse oximeter measurements were simultaneously taken and compared during induction of anesthesia, surgery, and in some cases during the postoperative period. Pulse oximeter saturation values were recorded by an Ohmeda Biox 3700 pulse oximeter, and the corresponding arterial saturations determined with a CO Oximeter (OSM2 Hemoximeter, Radiometer). The values lay in the range of 43%-100% arterial oxygen saturation. The results were evaluated while taking into account the steady state and non-steady state situations (i.e., when there were rapidly changing pulse oximetric saturation readings and difficulties in coordinating the comparative arterial measurements time-wise), as well as the equipment's internal characterization of the signal quality (High Quality Signal (HQS)/Low Quality Signal (LQS]. The correlation analysis for all comparative measurements, under both steady state and non-steady state conditions, gave a result of r = 0.927. When the comparison was restricted to the measurements in the steady state conditions, r = 0.935 resulted. The pulse oximetry saturation values had a tendency to lie below the corresponding arterial values. The fact that the pulse oximetry values were designated with HQS or LQS was no indication of a better or worse correlation with the arterial value.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Complications during and following radial artery cannulation: a prospective study.

One hundred and eighteen 20-g radial artery catheters were prospectively evaluated in 109 cardiovascular surgical patients. 0.024% papaverine in saline was used as a continuous flushing solution. Using the Doppler method, obstruction of the radial artery with the catheter in situ was found in 11 (9.8%) patients. Decannulation was performed at the end of the monitoring in 93 (78.9%) cases while 25 (21.1%) catheters had to be removed earlier. According to Allen's radial flush and Doppler evaluation after decannulation, three (2.5%) radial artery occlusions and one stenosis persisted. However, no vascular insufficiency occurred during the study period. Female patients developed more complications with the catheter in situ but not after catheter removal. Wrist size did not predict the complications. Age, concomitant diseases, traumatic cannulation, type of the surgery, longer cannulation time and perioperative complications did not influence the incidence of abnormal radial blood flow after decannulation. Our results confirm the low incidence of significant complications following radial artery cannulation.

Adult↗
PubMedDate not supplied

Cyanotic congenital heart disease and pregnancy: natural selection, pulmonary hypertension, and anesthesia.

Pregnancy carries substantial maternal and fetal risks in patients with uncorrected or palliatively corrected cyanotic congenital heart disease (CHD). In tricuspid valve Ebstein's anomaly, pregnancy is well tolerated. Maternal mortality in tetralogy of Fallot seems to be less than 10%, but it exceeds 50% in Eisenmenger's syndrome and primary pulmonary hypertension (PPH). Maternal hematocrit greater than 60%, arterial oxygen saturation lower than 80%, right ventricular hypertension, and syncopal episodes are poor prognostic signs. Maternal risk could be reduced by vaginal delivery. Continuous monitoring of arterial and central venous pressure, electrocardiography, and pulse oximetry are recommended for every anesthetic procedure. The use of a pulmonary artery catheter is controversial and probably should be avoided in parturients with cyanotic CHD or PPH. The choice of anesthetic technique and drugs per se is of secondary importance and should be governed by individual preferences. Titration of anesthetic drugs, general anesthesia with controlled ventilation, or, preferably, regional anesthesia with spontaneous breathing should be used cautiously to avoid worsening of the preexisting condition. Prevention of excessive erythrocytosis, volume and blood loss substitution, cardiocirculatory pharmacologic support, prophylaxis of infective endocarditis, and judicious use of anticoagulant drugs should be applied as indicated by the type and presentation of CHD. Poor outcome of pregnancy in PPH requires an early consideration of heart-lung or lung transplantation. Multidisciplinary team effort and prolonged monitoring in the intensive care unit are mandatory to ensure a favorable outcome for cyanotic CHD and PPH parturients.

Anesthesia↗
PubMedDate not supplied

Intercostal nerve block for lumpectomy: superior postoperative pain relief with bupivacaine.

STUDY OBJECTIVES: To investigate whether equipotent doses of lidocaine and bupivacaine were equally effective for intercoastal nerve blockade (ICNB) and whether a lower amount of lidocaine would be comparably effective. To see whether plasma levels of lidocaine with and without epinephrine and of plain bupivacaine would reach toxic ranges. Finally, to evaluate the duration of postoperative analgesia following general anesthesia and regional anesthesia with two different local anesthetics. DESIGN: Randomized, double-blind study, with control group administered general anesthesia. SETTING: Gynecologic operating room of a university hospital. PATIENTS: 48 adult ASA physical status I and II otherwise healthy patients undergoing lumpectomy. INTERVENTIONS: 36 patients received ICNB of T3-T6 unilaterally using either 4 ml/segment of 1.5% lidocaine with epinephrine 3.75 micrograms/ml (n = 10, Group A), 4 ml/segment of 2% lidocaine with epinephrine 5 micrograms/ml (n = 13, Group B), or 4 ml/segment of plain 0.5% bupivacaine (n = 13, Group C). The control group consisted of 12 patients (Group D) who received a general anesthetic using propofol, alfentanil, and nitrous oxide in oxygen for induction and maintenance of anesthesia. MEASUREMENTS AND MAIN RESULTS: In all three ICNB groups, the highest plasma concentrations were reached after 5 to 10 minutes following ICNB--i.e., a lidocaine plasma level of 2.77 +/- 0.5 micrograms/ml (mean +/- SEM) in Group A, a lidocaine plasma level of 2.78 +/- 0.2 micrograms/ml in Group B, and a bupivacaine plasma level of 1.44 +/- 0.2 micrograms/ml in Group C. There were no significant differences in plasma levels between 1.5% lidocaine and 2% lidocaine. For the first 90 minutes after surgery, higher postoperative pain scores were found in the control group than in the ICNB groups. Notably longer-lasting postoperative pain relief was achieved with plain bupivacaine. The number of women requiring postoperative analgesic medication, the time of first request, and the total amount of analgesic drugs administered during the 24 hours postoperatively were significantly lower in the regional anesthesia groups than in the general anesthesia group (p < 0.05). CONCLUSIONS: ICNB is an alternative to general anesthesia for female breast surgery. Both lidocaine with epinephrine and plain bupivacaine in the doses used did not raise venous plasma concentrations to levels considered potentially toxic. With respect to duration of postoperative pain relief and analgesic drug request, the local anesthetics (in particular, bupivacaine) were found to be superior to general anesthesia.

Breast Neoplasms↗
PubMedDate not supplied

Ventricular assist with heparin surface coated devices.

Heparin surface coated ventricular assist devices (VADs) were evaluated without systemic heparinization and compared with uncoated control VADs with systemic heparinization (bovine experiments, n = 8; bodyweight, 75 +/- 6 kg). No heparin was given in the study group, whereas heparin (300 IU/kg) was given before cannulation in the control group. Mean activated clotting time (ACT) was 127 +/- 12 sec before and 122 +/- 17 sec after 6 hours of left ventricular assist for coated (NS) versus 184 +/- 114 sec before and 650 +/- 240 sec after for uncoated (p less than 0.05) VADs. No difference was observed in platelet depletion, plasma hemoglobin, lactic dehydrogenase (LDH) production, mixed venous oxygen saturation, and VAD clot score. No VAD occlusions occurred. Ventricular assist can be achieved without systemic heparinization if VADs are improved.

Animals↗
PubMedDate not supplied

Pulmonary atresia with ventricular septal defect: a case for central venous pressure and oxygen saturation monitoring.

A 21-year-old patient with pulmonary atresia and ventricular septal defect (PA-VSD) was admitted to the hospital for tubal ligation. Invasive arterial and central venous (CVP) pressure, pulse oximetric oxygen saturation (SpO2), and (from the tip of oximetric central venous catheter) central venous oxygen saturation (ScvO2) and oxygen extraction rate (ExO2) were continuously monitored. Heart rate (range: 68-75 beat/min), mean arterial pressure (80-90 mmHg), CVP (7-10 mmHg), SpO2 (79-90 percent), ScvO2 (57-70 percent), and ExO2 (21-30 percent) remained stable during epidural anesthesia and transvaginal sterilization. Following an overnight stay (peak SpO2 92 percent; peak ScvO2 71 percent; through ExO2 21 percent), the oxygen data returned to baseline on awakening (SpO2 < 80 percent, ScvO2 < 55 percent, ExO2 > 35 percent), and the patient was discharged. In PA-VSD, a single-outlet double-ventricle anomaly, CVP reflects the preload of systemic ventricle. As the mixed venous oxygen saturation cannot be defined, ScvO2 is the best available indicator of the whole body oxygen consumption. Continuous monitoring of CVP, ScvO2 and ExO2 in the superior vena cava may provide more insight into the response to anesthesia and surgery in patients with PA-VSD.

Abnormalities, Multiple↗