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Biomedical subjects

A D Ivankovich

Publications and source records attributed to A D Ivankovich.

At least 55 records · Page 3Linked to original sources
PubMed1990

Comparative effects of esmolol and verapamil in a model of a supraventricular tachydysrhythmia.

Supraventricular tachydysrhythmias are a commonly encountered clinical problem after cardiothoracic surgery. Current choices for acute drug therapy of these dysrhythmias include intravenous verapamil as well as esmolol, but no data yet exist comparing the relative negative dromotropic (atrioventricular [A-V] nodal blocking) and negative inotropic effects of these agents. The purpose of this study was to compare the effects of esmolol with those of verapamil on systemic hemodynamics, coronary blood flow, and cardiac contractility at doses that produce a similar ventricular response rate in an animal model of a supraventricular tachydysrhythmia. Rapid electrical stimulation (800 impulses/min) of the left atrium in 14 dogs resulted in a rapid and irregularly irregular ventricular rhythm. Esmolol or verapamil were administered by bolus and then infusion to incrementally slow the average ventricular rate. Regional myocardial contractility was measured using the end-systolic pressure-length relationship (Ees). At drug doses that produced similar decreases in ventricular rate, esmolol produced a greater decrease in contractility (Ees: 284 +/- 46 to 40 +/- 22 mmHg/mm, LV dp/dt: 2,400 +/- 450 to 1,360 +/- 450 mmHg/sec) compared with that following verapamil (Ees: 297 +/- 57 to 116 +/- 25 mmHg/mm, LV dp/dt: 2,040 +/- 580 to 1,950 +/- 520 mmHg/sec). This was accompanied by a modest decrease in cardiac output in the esmolol group (2,800 +/- 940 to 2,290 +/- 730 ml/min) compared with an unchanged cardiac output as ventricular rate slowed in verapamil-treated animals. Stroke volume increased significantly in the verapamil-treated animals (10.9 +/- 4.0 to 18.5 +/- 4.6 ml), but remained unchanged following esmolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1989

Effect of helium-neon and infrared laser irradiation on wound healing in rabbits.

We examined the biostimulating effects of helium-neon laser radiation (HeNe; 632.8 nm), pulsed infrared laser radiation (IR; 904 nm), and the two combined on skin wound healing in New Zealand white rabbits. Seventy-two rabbits received either 1) no exposure, 2) 1.65 J/cm2 HeNe, 3) 8.25 J/cm2 pulsed IR, or 4) both HeNe and IR together to one of two dorsal full-thickness skin wounds, daily, for 21 days. Wound areas were measured photographically at periodic intervals. Tissue samples were analyzed for tensile strength, and histology was done to measure epidermal thickness and cross-sectional collagen area. Significant differences were found in the tensile strength of all laser-treated groups (both the irradiated and nonirradiated lesion) compared to group 1. No differences were found in the rate of wound healing or collagen area. Epidermal growth was greater in the HeNe-lased area compared to unexposed tissue, but the difference was not significant. Thus, laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased tensile strength on the opposite side as well.

Animals↗
PubMed1989

The impact of liver transplant programs on anesthesia personnel and services.

Liver transplantation procedures are being performed at an increasing number of hospitals throughout the United States. These procedures are challenging because of hemodynamic, metabolic, renal, and coagulation dysfunctions and may require prolonged periods of time for completion. Anesthesia departments are developing or managing teams of personnel to perform liver transplants. A survey was sent to directors of liver transplant anesthesia teams to investigate how teams were structured, compensated, and the impact of participation upon personnel involved. Thirty-nine centers were surveyed and 31 responded. The results showed an arithmetic doubling of cases for each of the last six years, most being performed at large medical centers (more than 759 beds) with populations served of 2 million or more. Cases were reported to average 13 hours in length and required a mean of five anesthesia personnel to complete. Compensation methods for work on a liver transplant team were variable; however, CRNAs and technicians received monetary reimbursement more frequently than physicians. Emotional responses of personnel were equally divided between favorable and unfavorable responses. Discriminate analysis showed that positive personnel attitudes were most closely tied to the presence of a protocol for breaks, call schedules, compensation, and the frequency of performing these cases. However, most protocols for personnel management were instituted in response to dissatisfaction. As the number of transplants per year increases, departments will need effective plans for personnel management to maximize departmental resources, increase research interest, and maintain personnel enthusiasm.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Does choice of anesthetic agent significantly affect outcome after coronary artery surgery?

A prospective study of 1094 consecutive adult patients undergoing coronary revascularization was undertaken to determine the effect of anesthetic technique on outcome. Patients received one of five primary techniques: high-dose fentanyl (greater than 50 micrograms/kg), moderate-dose fentanyl (less than 50 micrograms/kg), sufentanil (3-8 micrograms/kg), diazepam (0.4-1 mg/kg) with ketamine (3-6 mg/kg) or halothane (0.5-2.5% inspired concentration after thiopental induction). Supplemental inhalation anesthesia (enflurane, halothane, or isoflurane) was used in 60% of cases where the primary technique was intravenous based. Patients in the above anesthetic groupings had similar perioperative demographic and risk classifications. The overall incidence of postoperative myocardial infarction, postoperative low cardiac output state, and in-hospital death were 4.1, 5.6, and 3.1%, respectively. There were no significant differences in the incidence of these occurrences or in the incidence of serious pulmonary, renal, or neurologic morbidity or length of ICU stay among primary anesthetic techniques nor among supplemental inhalation agent groups. Multivariate discriminant analysis of this data suggests that a multitude of factors are significantly more important than anesthetic technique as determinants of outcome after coronary artery surgery.

Adult↗
PubMed1989

Effect of pulmonary artery catheterization on outcome in patients undergoing coronary artery surgery.

Previous studies have suggested that low-risk cardiac surgical patients may be safely managed without pulmonary artery catheterization (PAC). However, no prospective studies have determined whether PAC improves outcome in higher risk patients compared with that following central venous pressure (CVP) monitoring alone. The authors prospectively examined the incidence of and factors related to perioperative morbidity and mortality in 1094 consecutive patients undergoing coronary artery surgery managed with elective PAC (n = 537) or with CVP (n = 557). Perioperative risk factors and demographics that predict morbidity and mortality after cardiac surgery were used to quantify risk classification. Outcome was judged by length of ICU stay, occurrence of postoperative myocardial infarction, in-hospital death, major hemodynamic aberrations, and significant noncardiac systemic complications. No significant differences in any outcome variables were noted in any group of patients with similar quantitative risk classification managed with or without PAC, including those in the highest risk class. In addition, there were no significant differences in outcome among the 39 patients who would have been managed with CVP monitoring only, but who subsequently developed a clinical need for PAC based on the occurrence of serious hemodynamic events compared to patients who had PAC performed electively. This study suggests that PAC does not play a major role in influencing outcome after cardiac surgery, that even high-risk cardiac surgical patients may be safely managed without routine PAC, and that delaying PAC until a clinical need develops does not significantly alter outcome, but may have an important impact on cost savings.

Aged↗
PubMed1989

Synthetic erythrocytes.

Synthetic erythrocytes (SEs) are made by incorporation of stroma-free hemoglobin (SFH) or lipid-heme into liposomes. They form spontaneously at the interface between the phospholipid material and aqueous solution. SEs are spheroid vesicles with diameters between 0.01 and 4 microns, capable of carrying and delivering oxygen in a manner similar to red blood cells (RBCs). Oxygen-dissociation curve is virtually identical to that of RBCs, with P50 = 28 torr, and adjustable by the addition of 2,3-DPG or inositol hexaphosphate. Liposome/heme containing lipid-heme, a synthetic O2-carrying substance, is capable of carrying as much O2 as RBCs. Liposome-encapsulated SFHs have smaller O2-carrying capacity, but can be made to equal that of RBCs. Viscosity of SE suspensions is somewhat higher than blood's viscosity, but has otherwise similar rheologic properties. A large number of in vivo experiments with laboratory animals prove the ability of SEs to maintain life after virtually complete removal of blood. Cardiorespiratory functions remain near-normal, blood chemistry exhibits reversible mild changes, and vital organs do not show significant abnormalities. Blood coagulation is not affected. Hemoglobin does not appear in urine and plasma, indicating mechanical stability in circulation and absence of diffusion through the membrane. SEs do not cause significant acute toxicity. The absence of blood groups makes them a universal blood donor. However, massive doses suppress the reticuloendothelial system (RES). The animals undergoing total exchange transfusions may die of septic shock, apparently caused by nonsterile infusate in combination with strong suppression of the RES. Longevity of SEs in circulation is proportional to the dose. At doses corresponding to more than 90% exchange transfusions, half-life is longer than 24 h. Since all materials used in preparation of SEs are naturally occurring in blood, SEs are easily metabolized and eliminated without allergic reactions. The absence of membrane proteins and chemical stability of SFH and phospholipids promises long shelf-life. SE suspensions are difficult to sterilize, particularly against the viruses that may be present in SFH. However, the use of sterile procedures during manufacturing, and extraction of hemoglobin from animals bred under strict infection control may eliminate that problem.

Animals↗
PubMed1989

Comparison of viscoelastic measures of coagulation after cardiopulmonary bypass.

Postoperative hemorrhage remains a major cause of morbidity after cardiopulmonary bypass (CPB). Treatment remains empiric because of the need for immediate correction and the lack of availability of rapid intraoperative coagulation monitoring (except for ACT) at most institutions. Thrombelastography (TEG) and Sonoclot analysis (SCT) are measures of viscoelastic properties of blood which allow rapid intraoperative evaluation of coagulation factor and platelet activity as well as overall clot integrity from a single blood sample. Routine coagulation tests (RCT) including activated clotting time (ACT), prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen level (FIB), and platelet count (PLT) were determined and compared to TEG and SCT to assess which best predicted clinical hemostasis after CPB. Forty-two patients prospectively felt to be at high risk for excessive post-CPB bleeding had blood obtained for RCT, TEG, and SCT analysis before systemic heparinization and 30 min after protamine administration. Nine of 42 patients had excessive chest tube drainage, but no reoperations were required. After CPB, mean values for RCT were normal, but there were abnormalities in TEG and SCT parameters that reflect platelet-fibrin interaction. Both TEG and SCT were 100% accurate in predicting bleeding in these nine patients and, overall, both tests were significantly better predictors of postoperative hemorrhage than RCT. We conclude that viscoelastic determinants of clot strength may be abnormal after CPB and that SCT and TEG are, therefore, more useful than RCT for the detection and management of coagulation defects associated with CPB.

Adult↗
PubMed1988

Midazolam-sufentanil anaesthesia for phaeochromocytoma resection.

This is a case report of a 66-year-old patient to whom a combined infusion of midazolam and sufentanil was administered for phaeochromocytoma resection. With the exception of a drop in blood pressure immediately after tumour removal, significant intraoperative haemodynamic stability was observed. There was no need for the intraoperative administration of hypotensive or anti-arrhythmic drugs, nor was any prolonged postoperative anaesthetic effect noted. In this case, the combination of midazolam and sufentanil with N2O:O2 was successful in maintaining cardiovascular stability until the tumour was removed. The consequent drop in blood pressure responded to fluid infusion, a not uncommon event in phaeochromocytoma surgery. Although a prospective randomized study for resection of phaeochromocytoma showed that the choice of the anaesthetic technique is not a crucial factor in determining the patient outcome, we feel this technique of midazolam sufentanil is a worthy alternative to the use of inhalational anaesthetics. The lack of significant myocardial depressive effect of the two drugs, coupled with its simple administration, makes it a useful technique in the anaesthetic management of phaeochromocytoma resection.

Adrenal Gland Neoplasms↗
PubMed1988

Effects of high-dose fentanyl on fluid and vasopressor requirements after cardiac surgery.

The effects of two different anesthetic techniques on postoperative cardiopulmonary events, fluid and vasopressor requirements, and overall intensive care unit (ICU) course were studied in patients undergoing elective myocardial revascularization (CABG) (N = 20) or single cardiac valve replacement (N = 20). Patients were randomized to receive either high-dose fentanyl (F, 75 microg/kg followed by 0.3 microg/kg/min) or diazepam-ketamine (0.8 mg/kg D and 2 mg/kg K followed by 0.07 mg/kg/h D and 1 mg/kg/h K). No significant differences in preoperative demographics, prebypass hemodynamics, ischemic crossclamp, or total cardiopulmonary bypass times were noted. Patients receiving F had lower systemic arterial pressures and vascular resistances and required more vasopressors during the first 12 hours postoperatively. They also had a more positive cumulative fluid balance at 24 and 48 hours postoperatively, despite a higher incidence of postoperative diuretic use in CABG patients receiving F. Rectal temperature was significantly higher at four and eight hours postoperatively in F patients. Time until arousal and length of ICU stay were significantly greater with F, although duration of intubation did not differ between anesthetic techniques. Although the data does not provide an explanation for these differences, it indicates that these two techniques produce quite different physiologic responses in the postoperative period following cardiac surgery. In summary, it was found that F for cardiac surgery was accompanied by increased postoperative fluid and vasopressor requirements with increased Qsp/Qt and longer ICU stays compared to diazepam and ketamine. This study suggests that some anesthetic techniques may provide less complicated and less costly postoperative courses than others, with the same outcome after cardiac surgery. Information on the postoperative effects of long-acting anesthetic agents is sparse and more studies of these effects and their mechanisms are necessary because they may affect patient management after cardiac surgery.

Aged↗
PubMed1988

The incidence of venous air embolism during total hip arthroplasty.

Venous air embolism has been reported to occur during total hip arthroplasty. The incidence of venous air embolism, however, has not been previously studied in a large series using Doppler ultrasound and mass spectrometry. Seventy patients undergoing total hip arthroplasty were monitored for venous air embolism with precordial Doppler ultrasound, central venous catheter, end-tidal N2 and CO2 (mass spectrometry), and arterial blood gases (ABG). Changes in the monitored variables consistent with venous air embolism were noted in 57% by Doppler ultrasound, 9% by mass spectrometry, 4% by central venous catheter and 3% of the cases by ABG. A total of 77 Doppler ultrasound events were detected in 40 of the 70 patients studied. Hemodynamic changes consisting of either hypotension, defined as a greater than or equal to 20% decrease in mean arterial pressure (MAP), or cardiac dysrhythmia occurred during 43% of these events. The Doppler ultrasound was the only monitor that detected all cases of venous air embolism with concomitant hemodynamic changes. Air was aspirated from the central venous catheter during 10% of the detections of venous air embolism by Doppler ultrasound. Venous air embolism in total hip arthroplasty is a common event and may be responsible for hemodynamic changes previously ascribed to the use of methylmethacrylate cement. Routine monitoring with Doppler ultrasound appears warranted. The routine use of central venous catheterization may also be warranted.

Blood Gas Monitoring, Transcutaneous↗
PubMed1988

Minimal positive end-expiratory pressure (PEEP) may be "best PEEP".

In the absence of clinical trials, positive end-expired pressure (PEEP) has been accepted as efficacious for treatment of postoperative decreases in arterial oxygen tension (PaO2) from a variety of causes including adult respiratory distress syndrome (ARDS). PEEP is thought to increase PaO2 by alveolar recruitment, which in turn, has been hypothesized to play a decisive role in pulmonary recovery. One hundred and eighteen patients were followed prospectively, and after development of decreased PaO2, randomized to receive recruitive PEEP (determined by blood gas criteria) or supportive PEEP (the minimal PEEP required to maintain PaO2 above 60 mm Hg on .5 inspired O2 fraction (FIO2). No prognostic factors were significantly different between the two groups. Recruitive PEEP application in 22 patients yielded a significantly increased incidence of hypotension (55 percent), pneumothorax (20 percent), and death during treatment (27 percent) when compared to the 28 supportive PEEP patients who had no hypotension or pneumothorax and only one death during treatment (4 percent). After PEEP treatment, deaths in each group were similar (19 percent and 15 percent, respectively). We find no evidence that PEEP treatment promotes beneficial outcomes and conclude that recruitment attempts may be harmful.

Humans↗