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Biomedical subjects

I Dimich

Publications and source records attributed to I Dimich.

At least 19 recordsLinked to original sources
PubMed2000

Milrinone is superior to epinephrine as treatment of myocardial depression due to ropivacaine in pigs.

PURPOSE: To determine whether milrinone is more effective than epinephrine in the resuscitation of ropivacaine induced cardiotoxicity in pigs. METHODS: Arterial, pulmonary, and LVdP/dt catheters were placed in 12 anesthetized, intubated and mechanically ventilated pigs. They received ropivacaine iv to cardiovascular toxicity: 50% decrease in LVdP/dt, cardiac output and mean arterial pressure (MAP). Group I (n=6) was treated with 100 microg x kg(-1) milrinone iv, and Group II (n=6) received 0.5 mg epinephrine iv. Resuscitation was successful if cardiac output returned to baseline, and MAP reached 80% of baseline. RESULTS: After ropivacaine, MAP decreased from 88 +/- 7 to 49 +/- 8 mmHg (P < 0.05), CO decreased from 2.8 +/- 0.4 to 1.2 +/- 0.2 L x min(-1) (P < .05), HR decreased from 103 +/- 8 to 74 +/- 7 beats x min (P < 0.05) and LVdp/dt decreased from 1,950 +/- 130 to 755 +/- 125 mmHg (P < 0.05). The LV EDP increased from 5 +/- 1 to 8 +/- 1 mmHg (P < 0.05) and SVR from 2,317 to 3,000 +/- 120 dynes x sec(-1) x cm(-5). Electrocardiogram changes included increases in the QTU interval and QRS duration. In all animals, milrinone restored MAP, CO, SV, HR, and dP/dt to baseline and no animal developed arrhythmias. In contrast, epinephrine produced severe hypertension and tachycardia. There was no improvement in CO or SV, and SVR increased. Epinephrine caused A-V dissociation and ventricular arrhythmias in three animals. CONCLUSION: Milrinone, was more successful than epinephrine in resuscitating anesthetized pigs from ropivacaine-induced cardiovascular toxicity.

Amides↗
PubMed1998

Cardiovascular consequences of the concomitant administration of nifedipine and magnesium sulfate in pigs.

There is concern regarding the interaction of magnesium sulfate and nifedipine used concomitantly in obstetrical patients, because both are calcium channel antagonists and may induce myocardial depression as well as peripheral vasodilatation. The objective of this study was to determine the hemodynamic consequences of concomitant administration of nifedipine and magnesium sulfate in anesthetized pigs. Twelve pigs were anesthetized with sodium pentobarbital, intubated mechanically ventilated. Following placement of invasive monitors, baseline hemodynamic measurements were made. Animals were randomized to one of two groups. Group I received nifedipine first, and then magnesium sulfate. Group II received magnesium sulfate first, and then nifedipine. Hemodynamic measurements were recorded. Hypotension was treated with calcium chloride, ephedrine and phenylephrine. Nifedipine alone (Group I) decreased peripheral vascular resistance and mean arterial pressure (MAP) (P<0.05). Magnesium sulfate alone in group II decreased the first derivative of left ventricular pressure (LVdP/dt) and increased left ventricular end-diastolic pressure (LVEDP) (P<0.05). Magnesium sulfate also decreased peripheral vascular resistance and MAP The concomitant administration of nifedipine and magnesium sulfate in both groups I and 11 led to a further decrease in myocardial contractility, as evidenced by a decrease in LVdP/dt and increase in LVEDP (P<0.05). Treatment with calcium chloride or ephedrine was only partially successful in improving myocardial contractility. Phenylephrine increased peripheral vascular resistance and MAP, but did not improve myocardial function. In conclusion, the depressive effects of nifedipine and magnesium sulfate on the cardiovascular system are potentiated when administered concomitantly.

Journal Article↗
PubMed1997

Role of zatebradine and propranolol in attenuation of tachycardia produced by dobutamine in pigs.

BACKGROUND: Zatebradine is a new specific bradycardiac agent that selectively slows the depolarization in the pacemaker cells of the sinoatrial node. The purpose of our investigation was to determine whether the tachycardia induced by dobutamine can be attenuated by the administration of zatebradine. The results were compared with those produced by propranolol, which is used in the treatment of sinus tachycardia. METHODS: Twelve pigs were anesthetized with sodium pentobarbital, intubated, and ventilated. After baseline hemodynamic measurements were obtained, dobutamine was administered until the heart rate reached 25% above baseline. Animals were randomized to one of two groups. Group I received zatebradine, 0.5 mg/kg i.v., and Group II received propranolol, 0.5 mg/kg i.v. RESULTS: Dobutamine 10 micrograms.kg-1.min-1 increased the heart rate (FIR) by 25%, and increased mean arterial blood pressure (MAP) left ventricular (LV) dp/dt, and cardiac output (CO) (P < 0.05). Zatebradine decreased the HR to baseline (P < 0.05) without affecting left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), LV dP/dt, or CO. Stroke volume (SV) increased significantly (P < 0.05). Propranolol also reduced HR to baseline, but decreased LV dP/dt, LVSP, CO, and SV (P < 0.05). CONCLUSION: Zatebradine effectively attenuates the tachycardia caused by dobutamine in anesthetized pigs, without reducing cardiac performance.

Animals↗
PubMed1994

Intraoperative pulmonary oedema in a young cocaine smoker.

This is a case of a 28-yr-old man who underwent general anaesthesia for emergency repair of a right lid laceration and lacrimal apparatus. Following induction of anaesthesia and local nasal application of phenylephrine (0.25%) he developed transient elevation of blood pressure, which was treated immediately with labetalol. Subsequently the patient developed acute pulmonary oedema which responded to treatment with morphine and furosemide. The diagnosis of pulmonary oedema was confirmed by blood gas studies, chest x-ray and serial echocardiograms. Subsequent investigation revealed that he was a cocaine user, as the urine tested positive for cocaine. Considering that the patient was young and otherwise healthy and that the hypertension was transient, it is unlikely that phenylephrine was the main cause of pulmonary oedema. Cardiac morbidity was most likely precipitated by the interaction of phenylephrine-induced hypertension with a cocaine-depressed myocardium.

Adult↗
PubMed1994

Arrhythmogenic potential of dopexamine hydrochloride during halothane anaesthesia in dogs.

Dopexamine hydrochloride (Dopacard) is the novel synthetic catecholamine designed for use in the acute management of a low cardiac output status. In addition to dopaminergic receptor stimulation, dopexamine hydrochloride is a potent beta 2 adrenoceptor agonist with negligible direct beta 1 and no alpha adrenergic effect. The objective of this study was to compare the arrhythmogenic effects of dopexamine hydrochloride and dopamine in dogs anaesthetized with halothane (1.2 MAC). The starting dose for dopexamine hydrochloride was 3.5 micrograms.kg-1.min-1 and for dopamine was 5 micrograms.kg-1.min-1. Concentrations of the drugs were increased until four or more premature ventricular contractions within 15 seconds were produced. All dogs developed ventricular tachycardia when dopamine was administered in concentrations ranging between 18-20 micrograms.kg-1.min-1. Unlike dopamine, dopexamine hydrochloride even at concentrations as high as 50 micrograms.kg-1.min-1 did not induce any atrial or ventricular ectopic beats. Lack of beta 1 and alpha adrenergic agonist effects is a likely explanation for low arrhythmogenicity of dopexamine hydrochloride. Both drugs increase cardiac output; dopexamine hydrochloride primarily by a dose-related increase in heart rate and increased afterload. At the maximal concentration dopexamine hydrochloride increased heart rate from 114 to 150 beat.min-1, mean arterial pressure decreased from 81 mmHg to 45 mmHg and SVR decreased from 2418 to 962 dyne.sec-1cm-5. Myocardial contractility increased only moderately, as evaluated by dP/dt, which increased from 1290 to 1696 mmHg.sec-1. Dopamine had a more marked inotropic effect: the dP/dt increased, at the maximal concentration, from 1480 to 2570 mmHg.sec-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1992

A comparison of esmolol and labetalol for the treatment of perioperative hypertension in geriatric ambulatory surgical patients.

This is an open randomized study comparing the efficacy and safety of i.v. esmolol and labetalol in the treatment of perioperative hypertension in ambulatory surgery. Twenty-two elderly patients undergoing cataract surgery under local anaesthesia were studied. The main inclusion criteria were development of systolic blood pressure greater than 200 mmHg or diastolic greater than 100 mmHg. Esmolol was given as a bolus 500 micrograms.kg-1 i.v. followed by a maintenance infusion (150-300 micrograms.kg-1.min-1). Labetalol was given as a bolus of 5 mg i.v. followed by 5 mg increments as needed up to a maximum of 1 mg.kg-1. Esmolol and labetalol both produced reductions in systolic and diastolic blood pressure (P less than 0.05) within ten minutes of administration which lasted for at least two hours. Reduction of blood pressure by esmolol was accompanied by a decrease in HR (P less than 0.05). Two patients developed extreme bradycardia (HR less than 50 beats.min-1) and esmolol had to be discontinued. Labetalol, in contrast, induced only a moderate decrease in HR. None of the patients treated with labetalol experienced any prolonged side effects such as orthostatic hypotension. In conclusion, esmolol may produce considerable bradycardia in elderly patients when hypertension is not accompanied by tachycardia. Labetalol was easier to administer in the ambulatory setting and one-tenth the cost of esmolol.

Adrenergic beta-Antagonists↗
PubMed1992

Esmolol prevents and suppresses arrhythmias during halothane anaesthesia in dogs.

The antiarrhythmic effect of esmolol, a selective beta 1 adrenoreceptor blocker, was evaluated in the presence of epinephrine induced arrhythmias in dogs (n = 6). The arrhythmogenic dose of epinephrine (ADE) during 1.2 MAC halothane in dogs was increased from 3.23 +/- 0.25 (mean +/- SD) to 30.90 +/- 3.56 micrograms.kg-1.min-1 (P less than 0.001) by the prior administration of esmolol 0.5 microgram.kg-1 bolus followed by an infusion at the rate of 150 micrograms.kg-1.min-1. Higher esmolol infusion doses of 200 micrograms.kg-1.min-1 further increased ADE to 99.0 +/- 2.92 micrograms.kg-1.min-1 (P less than 0.001). After discontinuation of esmolol and during continued halothane anaesthesia, ventricular tachycardia was induced by increasing the infusion rate of the 100 micrograms.ml-1 solution of epinephrine. In all dogs ventricular tachycardia was restored to sinus rhythm by a bolus dose of esmolol (1 microgram.kg-1). We conclude that esmolol pretreatment increases the ADE during halothane anaesthesia in dogs. Our data suggest that esmolol may be useful as an antiarrhythmic agent in the management of epinephrine-related ventricular arrhythmias during anaesthesia in man.

Adrenergic beta-Antagonists↗
PubMed1991

Evaluation of oxygen saturation monitoring by pulse oximetry in neonates in the delivery system.

The pulse oximeter was evaluated for use in neonates in the delivery room. One hundred neonates, delivered vaginally or by Caesarean section with general or epidural anaesthesia, were studied. After delivery, pulse oximetry probes were placed simultaneously on the ulnar side of the right hand and on the right Achilles tendon to determine whether there was a difference in arterial oxygenation (SpO2). Measurements of SpO2 were taken at 1, 5, 10 min, and 24 hr after delivery. At one and five minutes, SpO2 recorded from the right hand was higher than that recorded from the lower extremities (71.9% +/- 6.5% vs 63.4% +/- 4.3% and 83.3% +/- 4.2% vs 76% +/- 4.1%, mean +/- SD, respectively). At ten minutes these differences diminished, and had almost completely disappeared after 24 hr. These results can be explained by the presence of R-L shunting at the ductus arteriosus level, producing reduced SaO2 in the lower extremities. Oxygen saturation did not differ between neonates delivered vaginally or by Caesarean section, regardless of the presence or type of anaesthesia. We concluded that neonates remain relatively desaturated in the immediate postpartum period and that the SpO2 obtained from the right hand is a better index of neonatal oxygenation than that obtained from the heel.

Achilles Tendon↗
PubMed1989

Cardiovascular effects of a nifedipine infusion during fentanyl-nitrous oxide anesthesia in dogs.

The hemodynamic effects of a nifedipine infusion were investigated in eight dogs given fentanyl/pancuronium/nitrous oxide/oxygen anesthesia. Nifedipine (20 micrograms/kg) was given intravenously over two minutes immediately prior to each 30-minute infusion at 2 micrograms/kg/min, 4 micrograms/kg/min, and 6 micrograms/kg/min. The range of plasma nifedipine levels obtained was 52.1 to 113.7 ng/mL. The predominant hemodynamic effects were significant reductions in systemic vascular resistance (SVR) and mean aortic pressure (MAP), accompanied by a rise in cardiac index and heart rate (HR). Administration of calcium chloride (20 mg/kg) after the nifedipine infusion had no effect on SVR or MAP, but HR was significantly reduced. Serum epinephrine and norepinephrine levels increased after the infusion of nifedipine and suggested that fentanyl did not completely overcome the sympathetic response to the profound vasodilatation. The resulting tachycardia in combination with diastolic hypotension from nifedipine could have a detrimental effect on the myocardial oxygen balance.

Anesthesia, Inhalation↗
PubMed1989

Comparative hemodynamic effects of labetalol and hydralazine in the treatment of postoperative hypertension.

The antihypertensive efficacy and safety of IV labetalol were evaluated and compared with the efficacy and safety of IV hydralazine in the treatment of postoperative hypertension. Twenty patients undergoing major noncardiac surgery were entered into the study. Patients were randomized and treated for postoperative hypertension with either labetalol (n = 10) or hydralazine (n = 10). Labetalol and hydralazine both produced significant reductions in arterial blood pressure (p less than 0.001) within 10 minutes, which lasted at least 2 hours. In addition, labetalol produced a significant reduction in the heart rate and rate-pressure product without creating any adverse effects. In contrast, hydralazine produced significant sinus tachycardia requiring IV propranolol in three patients, two of whom developed transient ST segment depression. These results indicate that labetalol is safe and effective for the control of postoperative hypertension, especially in those patients who are least able to tolerate tachycardia.

Aged↗
PubMed1989

Hemodynamic effects of verapamil during fentanyl-nitrous oxide anesthesia.

The hemodynamic effects of a verapamil infusion were investigated in six dogs given fentanyl-nitrous oxide anesthesia. Verapamil, 0.2 mg/kg, was given followed by an infusion of 3, 6, and 9 micrograms/kg per minute, which produced plasma verapamil concentrations ranging from 98 to 204 ng/ml. Verapamil significantly reduced the systemic vascular resistance index and mean arterial pressure. The decrease in afterload led to an increase in cardiac index, since there was little change in myocardial contractility (LV dP/dt). Administration of calcium chloride, 20 mg/kg, did not reverse the hemodynamic effects of verapamil. The data indicate that in dogs verapamil can be given, even in high concentrations, during fentanyl-nitrous oxide anesthesia without serious adverse electrophysiologic or hemodynamic consequences.

Anesthesia, Inhalation↗
PubMed1988

Reversal of the adverse cardiovascular effects of intravenous diltiazem in anesthetized dogs.

Intravenous diltiazem can be used to treat myocardial ischemia, hypertension, and supraventricular dysrhythmias, but significant adverse effects including atrioventricular block and hypotension have been reported. At the present time, there is controversy as to which drug is most effective in reversing these sequelae. This study was designed to assess the effectiveness of calcium chloride v epinephrine in reversing these side effects. The hemodynamic and electrophysiologic effects of diltiazem infusion were investigated in eight dogs anesthetized with fentanyl and nitrous oxide/oxygen. This study confirmed that diltiazem infusions in high concentrations produced predominantly atrioventricular conduction depression followed by profound hypotension. Epinephrine infusion proved to be most effective in attenuating and eliminating each of these deleterious side effects. In contrast, calcium chloride did not significantly increase heart rate or blood pressure or reverse atrioventricular block. In two instances calcium chloride produced further depression of atrioventricular conduction, leading to severe bradycardia and sinus arrest. Although calcium chloride increased left ventricular contractile force (LV dP/ dt) and cardiac index (CI), mean arterial pressure was not affected and SVR was further decreased. This study indicates that calcium chloride should not be given to reverse the side effects of diltiazem in the presence of atrioventricular conduction block or profound hypotension. Calcium chloride is indicated only when isolated myocardial depression is present and after the calcium channels have been reopened by epinephrine.

Anesthesia↗
PubMed1988

Haemodynamic effects of diltiazem during fentanyl-nitrous oxide anaesthesia. An in vivo study in the dog.

The haemodynamic effects of diltiazem were studied in six dogs during fentanyl-nitrous oxide (in oxygen) anaesthesia. A bolus of diltiazem 300 micrograms kg-1 was given, followed by infusions at 30, 60 and 90 micrograms kg-1 min-1 which produced plasma diltiazem concentrations of 392 +/- 30, 908 +/- 54 and 1483 +/- 134 ng ml-1, respectively. Diltiazem significantly reduced systemic vascular resistance index, mean arterial pressure, heart rate and PR interval. The decrease in afterload increased cardiac index, since there was little change in myocardial contractility (LV dP/dt). Five dogs developed second degree atrioventricular (AV) block in association with the highest dose. Administration of calcium chloride 20 mg kg-1 did not reverse the haemodynamic or electrophysiological effects of diltiazem. Isoprenaline increased heart rate and restored sinus rhythm in four dogs with AV block.

Anesthesia, General↗
PubMed1981

Ketamine-diazepam anaesthesia in a patient with carcinoid syndrome.

The use of ketamine in patients with carcinoid syndrome is controversial because of the catecholamine response to this agent. Prior administration of diazepam modifies the catecholamine response to ketamine and may make its use in such patients safe. The successful use of a diazepam-ketamine technique for anaesthesia of a patient with malignant carcinoid syndrome and associated tricuspid valve disease who underwent laparotomy and hepatic artery ligation is described. The theoretical advantages of safe ketamine anaesthesia in carcinoid patients are discussed and the relevant literature reviewed. To the authors' knowledge the successful use of ketamine anaesthesia in carcinoid syndrome has not previously been reported.

Aged↗
PubMed1980

Sympathetic nervous system tonicity and post-coronary artery bypass hypertension.

To elucidate the pathogenesis of hypertension following coronary bypass surgery, blood pressure and plasma catecholamine concentration were measured in 28 patients with coronary artery disease who were undergoing myocardial revascularization procedures. Measurements were obtained on arrival in the operating room and 1 and 4 h after surgery. One hour after surgery, plasma norepinephrine (NE) increased significantly by 495 +/- 108 pg/ml (P less than 0.001) in the coronary artery disease group which developed hypertension, but the increase was not significant in the coronary artery patients who remained normotensive after surgery. However, 4 h after surgery, plasma NE increased significantly and to the same extent in both coronary artery disease groups, regardless of the change in blood pressure. Plasma epinephrine (E) also increased significantly 1 and 4 h after surgery in both groups. The observed change in plasma catecholamine concentration is direct evidence that the stress of surgery is a potent adrenergic stimulus, but the hemodynamic significance of the plasma catecholamine change remains unclear.

Blood Pressure↗
PubMed1979

Anaesthetic considerations in the prolonged Q-T interval (LQTS): a case report.

A case of prolonged Q-T interval syndrome (LQTS) with ventricular dysrhythmias is presented. The patient was unresponsive to medical treatment. Left stellate ganglion block, followed by surgical excision of the ganglion, resulted in reversion to normal sinus rhythm. The causes of LQTS, its treatment and the effects of anaesthetic agents are discussed.

Adult↗