PubMed Health⌕ Search

Biomedical subjects

A D Ivankovich

Publications and source records attributed to A D Ivankovich.

At least 73 records · Page 4Linked to original sources
PubMed1988

Inadvertent subdural injection: a complication of an epidural block.

Twenty-one hundred eighty two consecutive lumbar epidural injections were studied to determine the incidence of inadvertent subdural block retrospectively. A subdural block is defined as an extensive neural block in the absence of subarachnoid puncture, that is out of proportion to the amount of local anesthetic injected. Subdural injection is a complication of epidural block that probably occurs more frequently than previously recognized. An earlier report has estimated the incidence of subdural block to be 0.1%. This study, however, reports an incidence of 0.82% from a sample size of 2182 patients. Cadaveric dissection was also performed, further clarifying the presence and anatomic position of the subdural space.

Adolescent↗
PubMed1988

Treatment of decompression sickness with a perfluorocarbon emulsion (FC-43).

Decompression sickness is caused by the production of tissue and blood stream inert gas bubbles. Perfluorocarbon emulsions (PFC) have enhanced O2 and N2 solubilities as well as a small particle size as properties. The effects of treatment with a PFC (FC-43) and 100% oxygen on decompression sickness were investigated in 24 Sprague-Dawley rats compressed to 6.8 ATA and rapidly decompressed. Survival in animals receiving PFC and 100% oxygen was significantly longer (P = 0.01) than in those receiving a 6% hetastarch (H) treatment. The PFC survivors at 24 h did not demonstrate any neurologic deficits, whereas the 1 H animal surviving at 24 h was ataxic and not eating. Those animals who died most often did so within minutes after decompression, suggesting a hemodynamic demise. We conclude that PFC treatment when coupled with 100% oxygen breathing provides both hemodynamic and neurologic protection from decompression sickness.

Animals↗
PubMed1988

Comparison of continuous epidural infusion of fentanyl-bupivacaine and morphine-bupivacaine in management of postoperative pain.

The short duration of epidural fentanyl has limited its direct comparison with epidural morphine in previous reports. The following study was performed of continuous postoperative epidural infusions at 5 ml/hr fentanyl 10 micrograms/ml (n = 59) or morphine 0.1 mg/ml (n = 48), both with bupivacaine 0.1%, in patients having cesarean sections. Postoperative evaluations included the frequency and magnitude of clinically evident respiratory depression, the adequacy of analgesia, nausea, pruritus, the ability to ambulate, and other side effects for 24 hours. Analgesia and the number of supplemental narcotic injections needed were similar in both groups. The incidence of nausea and pruritus was significantly less in the patients receiving fentanyl. No patient developed respiratory depression in either group. Patient and staff acceptance of the continuous epidural technique was excellent because there were only minor catheter-related problems associated with its use. It is concluded that continuous epidural fentanyl combined with bupivacaine offers excellent postoperative analgesia with minimal side effects.

Bupivacaine↗
PubMed1987

Vasopressor challenges during chronic MAOI or TCA treatment in anesthetized dogs.

Ten male mongrel dogs were treated in Phase I with tranylcypromine, 6 mg/kg IM b.i.d., for 21 days. Dogs were anesthetized at weekly intervals before, during, and up to four weeks after drug treatment with a combination of amylbarbital, 25 mg/kg, 1% enflurane in 70:30 N2O:O2 and fentanyl, 500 mcg. Bolus IV injections of norepinephrine, 0.1-0.6 mcg/kg, and ephedrine, 0.03-0.12 mg/kg were given while continuously recording arterial blood pressure, lead II of the ECG, heart rate, and rectal temperature. Awakening times were noted. In Phase II, the dogs were given imipramine, 25 mg/kg IM b.i.d., for 21 days. During Phase III, 14 days of tranylcypromine, 7 days of tranylcypromine plus imipramine, and 7 days of imipramine were administered. Anesthetic techniques were repeated in phases II and III. The fourth phase consisted of tranylcypromine injections, 6 mg IM b.i.d., and anesthesia with amylbarbital, 25 mg/kg, 2.5% enflurane in 70:30 N2O:O2. Vasopressor challenges were repeated during each phase of the study. Following induction of anesthesia and prior to fentanyl challenge, baseline blood pressures and heart rates did not differ from control in Phase I, II, and III of this study. Responses to norepinephrine during all of the tranylcypromine phases were not significantly different from control but ephedrine responses were prolonged, peaking by the second week of treatment. During Phase II, dysrhythmias occurred following norepinephrine and ephedrine with one lethality following norepinephrine, 0.2 mcg/kg. Responses to norepinephrine and awakening times were significantly greater during Phase II compared to Phase I. In Phase III, during the first week of combined therapy the responses to norepinephrine were significantly greater than any other week of this phase. During Phase IV, resting blood pressure and the ephedrine responses were significantly increased during tranylcypromine when the anesthesia regimen did not include fentanyl. These results suggest that during initial treatment with tranylcypromine or imipramine, cardiovascular responses to vasopressor challenges were predicted by the pharmacology of the antidepressant. During tranylcypromine phases, we did not observe exaggerated cardiovascular effects during anesthesia and vasopressor challenges as had been previously reported.

Anesthetics↗
PubMed1987

Thromboelastography as an indicator of post-cardiopulmonary bypass coagulopathies.

Postoperative hemorrhage in patients undergoing open-heart surgery is a major cause of morbidity and mortality. Monitoring of coagulation in these patients has routinely involved the activated clotting time. Thromboelastography is currently used as a monitor of coagulation during liver transplantation. The thromboelastogram, by providing information on the interaction of all the coagulation precursors, gives more clinically useful information on coagulation than that available from the coagulation profile or the activated clotting time alone. This study was done to assess the usefulness of thromboelastography in open-heart surgery. Thirty-eight patients (29 undergoing coronary artery bypass grafting and 9 undergoing valve replacement) were studied with activated clotting time, thromboelastography, and coagulation profiles during three periods: before bypass, during bypass, and after protamine administration. Thromboelastography was a significantly better predictor (87% accuracy) of postoperative hemorrhage and need for reoperation than was the activated clotting time (30%) or coagulation profile (51%). Thromboelastography is easy to use and provides diagnostic data within 30 minutes of blood sampling.

Blood Coagulation Disorders↗
PubMed1987

Protection from coronary air embolism by a perfluorocarbon emulsion (FC-43).

The protective effects of a perfluorocarbon emulsion (FC-43) against the physiological sequelae of selective coronary air embolism (CAE) were examined in dogs. Animals were randomly assigned to two groups: group 1 received 20 mL/kg of 6% hetastarch in 0.9 normal saline solution with 280 mg/L of CaCl2; group 2 received 20 mL/kg of FC-43 (Oxypherol, Alpha Therapeutic Corp, Los Angeles). Infusion time for both groups was 30 minutes. Following a ten-minute stabilization period, a 0.02-mL/kg bolus of air was injected into the left anterior descending coronary artery distal to the first branch. Surface and epicardial ECGs, systemic BP, pulmonary artery pressure, central venous pressure, left ventricular pressure, left ventricular end-diastolic pressure (LVEDP), dP/dtmax, and Vmax were recorded continuously. Cardiac output (by thermodilution technique), myocardial creatine phosphokinase levels and the lactic acid concentration were measured. The study revealed a significantly lower systemic mean arterial pressure (MAP), LVEDP, left ventricular stroke work index (LVSWI), and right ventricular stroke work index (RVSWI) in the group receiving the FC-43 prior to receiving CAE. Possible causes of the differences are a species-specific direct vasodilating effect of FC-43 or histamine release. Following CAE, myocardial function as measured by dP/dtmax, Vmax, and MAP was lower in group 1 during the first five minutes following CAE. ECG tracings showed all of the ten group 1 dogs had ST-T changes (greater than 2 mm), and six of the ten had ventricular dysrhythmias or conduction defects. Only one of the group 2 dogs showed ST-T wave changes (P = .0006, Fisher's exact test), and none had dysrhythmias (P = .005, Fisher's exact test).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The effect of chronic subarachnoid bupivacaine infusion in dogs.

A functional and histologic examination of the effect of the continuous intrathecal administration of bupivacaine was made in five dogs. After a partial laminectomy at L5, a silicone rubber catheter was inserted into the subarachnoid space and advanced 10 cm cranially. A model 400 Infusaid pump, used for drug delivery, was placed in a subcutaneous pocket between the 13th rib and iliac crest. Drug infusions were individually adjusted and maintained at a concentration such that the animal just exhibited slight gait impairment. Daily bupivacaine doses ranged from 5.7-11.1 mg. Infusions were maintained for a period of 3-16 weeks. Light microscopic examination of spinal cord and roots revealed no abnormalities. A focal mononuclear cell infiltration of the leptomeninges was seen in two drug animals, as well as one catheter control animal. One of the 16-week animals had a residual limp upon drug removal. While we were not able to quantitatively assess the degree of sensory motor dissociation, the results of this study suggest that chronic intrathecal bupivacaine infusion through an implantable pump system may be a short-term alternative to intrathecal morphine in the control of cancer pain.

Anesthesia, Spinal↗
PubMed1987

Effects of nitrous oxide on coronary perfusion after coronary air embolism.

Coronary air embolism (CAE) can occur after heart surgery whenever air is present in the left heart or proximal aorta. When CAE occurs, its sequelae can range from electrocardiographic changes of ischemia to severe myocardial dysfunction and cardiac arrest. Since N2O has been shown to have detrimental effects in the presence of coronary obstructions, as well as the tendency to enlarge air emboli, the authors tested the hypotheses that N2O would enhance the deleterious effects of CAE, and that discontinuing N2O at the time of CAE would minimize those effects. The effects of ventilation with and without N2O on the cardiac insult due to left anterior descending CAE (0.02 ml.kg-1) were studied in 27 swine. Global cardiovascular changes that occurred after CAE included decreases in cardiac output, systemic arterial and coronary perfusion pressure, and LV dP/dt, as well as increases in LVEDP. These parameters returned towards baseline over time when N2O was discontinued at the time of CAE. Maintenance of N2O in the inspired gas after CAE occurred was uniformly fatal within 2-4 min in this model. Regional myocardial ischemia was significantly greater in animals receiving N2O, as documented by: 1) a greater incidence of elevations of epicardial ST-segments exceeding 3 mm from baseline in embolized and non-embolized coronary artery distributions, 2) a greater incidence of dysrhythmias (greater than 6 PVCs.min-1), 3) longer duration of depression of coronary blood flow, 4) longer duration of post-ischemic coronary hyperemia, and 5) larger decreases with less recovery over time of regional myocardial lactate extraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Cardiorespiratory effects of exchange transfusions with synthetic erythrocytes in rats.

Synthetic erythrocytes (SE) can maintain life with near-normal hemodynamics in rats with hematocrits (Hct) 45% below the lethal levels, as shown when we exchanged virtually all their blood. We compared cardiorespiratory variables between the SE and control animals, which were hemodiluted with 7% albumin, at the 78% exchange level. In addition, SE animals at 92% exchange were compared with the 78% exchange and baseline levels. All our control rats died at Hct above 5% with corresponding oxygen-carrying capacity of 2.65 ml/dl. All SE rats survived, having a final Hct of 2.96% with an oxygen-carrying capacity of 7.05 ml/dl. SE animals maintained normal BP and marginally increased cardiac output, while control animals did not. Vascular resistance of control animals at 78% exchange was reduced to 30%, while in SE animals at 92% exchange, vascular resistance was lowered to 80% of baseline values.

Animals↗
PubMed1987

Measurements of viscosity of synthetic erythrocyte suspensions.

Measurements were made of the viscosity of suspensions of synthetic erythrocytes composed of hemoglobin solutions encapsulated in liposomes, as a function of shear rate, temperature, suspension concentration, lipid membrane composition, and the viscosity of the suspending medium. It was found that the viscous behavior of the synthetic erythrocyte suspensions was non-Newtonian and nearly the same as that of suspensions of natural erythrocytes prepared similarly, with the major difference being that synthetic erythrocyte suspensions are somewhat more viscous. Suspensions of Fluosol FC-43 prepared similarly were found to be essentially Newtonian fluids, and substantially different and more viscous than either erythrocyte suspension. The higher viscosity of synthetic erythrocyte suspensions probably accounts for the ability of these suspensions to maintain normal systemic vascular resistance in transfusion experiments, in spite of the fact that synthetic erythrocytes are smaller than natural erythrocytes.

Blood Proteins↗
PubMed1987

Effects of progressive blood loss on coagulation as measured by thrombelastography.

The effects of progressive blood loss on coagulation were studied in 87 adults (age 23-66 yr) undergoing a variety of operations under general anesthesia. None had preoperative alterations in coagulation or liver function and none were receiving anticoagulant or antiplatelet medication. Whole blood coagulation status was quantitated using thrombelastography (TEG). Blood samples for TEG were obtained 5 min before and 15 min after induction of anesthesia, after each increment of blood loss (EBL) equalling 5% of estimated blood volume (EBV), at the end of surgery, and 2 hr post-operatively. Patients with EBL exceeding 0.15 EBV were given packed red cells and crystalloid solution. Patients with EBL less than 0.15 EBV received only crystalloid. Thrombelastography analysis showed a trend toward increased coagulability with progressive blood loss. Two of four patients with 80% loss of EBV maintained normal to enhanced coagulation status, although the other two developed clinical and thrombelastographic evidence of coagulopathy. Thrombelastography allowed rapid intraoperative diagnosis and specific treatment of loss of platelet activity in the latter two patients. We conclude that during moderate to massive blood loss, use of supplemental fresh frozen plasma and/or platelets should be reserved for patients with documented defects in coagulation. Thrombelastography is useful for the detection and management of coagulation defects associated with intraoperative blood loss.

Adult↗
PubMed1986

Protection from venous air embolism with fluorocarbon emulsion FC-43.

Intraoperative venous air embolism (VAE) occurs frequently in some surgical settings and may cause devastating hemodynamic consequences. Perfluorocarbon emulsions have been investigated as artificial oxygen carrying medias. They also have the properties of enhanced nitrogen solubility and a small particle size. FC-43 (Oxypherol, Alpha Therapeutic Corp., Los Angeles, California) was compared to three other volume expanders in 91 New Zealand White laboratory rabbits exposed to continuous VAE. The animals were anesthetized and ventilated by one of four modalities. They then received one of the volume expanders at 20 cc/kg over 30 min. After a 10-min stabilization period, a constant femoral venous air infusion (0.25 cc/kg/min) was begun and continued until death. Time until death, total volume of air infused, femoral arterial pressure, central venous pressure, and ECG (Lead II) were recorded. Death was defined as the cessation of pulsatile blood pressure. Arterial and central venous gases were analyzed pre and post volume expansion and at intervals of every 5 min after the beginning of the femoral air infusion. Results showed a significant prolongation of life for the animals receiving FC-43 at 10 and 20 cc/kg as a volume expander and mechanically ventilated with 100% oxygen as compared to all other groups (P less than 0.05). PaO2 and PvO2 were consistently higher in the group receiving FC-43 as a volume expander. Central venous pressure was lower during air embolism in the FC-43 group. The mechanism for the enhanced survivability of rabbits pretreated with FC-43 volume expansion exposed to VAE is under further investigation.

Animals↗