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Biomedical subjects

A Fieldman

Publications and source records attributed to A Fieldman.

15 recordsLinked to original sources
PubMed1992

Effects of different dosages and modes of sodium bicarbonate administration during cardiopulmonary resuscitation.

Systemic acidosis occurs during cardiac arrest and cardiopulmonary resuscitation (CPR). The present study investigated the effect of different modes of sodium bicarbonate administration on blood gas parameters during CPR. Arterial and venous blood gases were obtained during 10 minutes of CPR which was preceded by 3 minutes of unassisted ventricular fibrillation in 36 dogs. Following 1 minute of CPR, the animals received one of four treatments in a randomized and blinded manner: normal saline (NS), sodium bicarbonate bolus dose 1 mEq/kg (B), sodium bicarbonate continuous infusion 0.1 mEq/kg/min (I), and sodium bicarbonate bolus dose (0.5 mEq/kg) plus continuous infusion 0.1 mEq/kg/min (L+I). Eleven dogs completed NS, 8 B, 8 I, and 9 L+I protocol. Following NS infusion, both arterial and venous pH declined consistently over time. Significant differences compared with NS treatment in venous pH were observed at 12 minutes of ventricular fibrillation (L+I, 7.27 +/- 0.05; NS, 7.15 +/- 0.05; B, 7.20 +/- 0.05; I, 7.24 +/- 0.04, each bicarbonate treatment versus NS, and L+I versus B, (P < .05). The B group had an elevated venous PCO2 (mm Hg) concentration following 6 minutes of ventricular fibrillation compared with NS, L+I, and I groups (81 +/- 14 versus 69 +/- 10 versus 68 +/- 10 versus 71 +/- 8, respectively, (P = .07). Arterial pH and PCO2 values showed a similar trend as the venous data with the L+I group demonstrating arterial alkalosis (pH > 7.45) at 12 minutes of ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1992

Diltiazem improves resuscitation from experimental ventricular fibrillation in dogs.

OBJECTIVE: To determine the effect of diltiazem on survival immediately after cardiac arrest and cardiopulmonary resuscitation (CPR) in dogs. DESIGN: Prospective, double-blind, randomized trial. SETTING: Laboratory at a large, university-affiliated medical center. SUBJECTS: Twenty-eight mongrel dogs, weighing 12 to 16 kg. INTERVENTIONS: After the administration of anesthesia, catheters were placed in the pulmonary artery, aortic arch, left ventricle, right ventricle, and great cardiac vein (12 dogs) for sample collection, pressure determinations, and induction of ventricular fibrillation. Dogs were randomized to receive either diltiazem, calcium chloride, or placebo (saline) either before or early during CPR. Dogs underwent 3 mins of unassisted fibrillatory arrest followed by 10 mins of standard CPR using a pneumatic device. After 13 mins of ventricular fibrillation, defibrillation was attempted repeatedly for less than or equal to 10 mins. Successful resuscitation was defined as an organized rhythm with an unassisted systolic BP of greater than 60 mm Hg for greater than or equal to 2 mins. MEASUREMENTS AND MAIN RESULTS: The resuscitation rate was significantly greater in diltiazem-treated animals (100%) than in those dogs receiving calcium (57%) or placebo (29%). Diltiazem-treated animals were resuscitated faster and required fewer defibrillation attempts than did dogs in the other groups. During CPR, coronary artery perfusion pressure and blood gases (arterial, venous, and myocardial) were similar among treatment groups. CONCLUSIONS: Diltiazem improves the resuscitation from experimentally induced ventricular fibrillation when administered before or early during CPR. This response may have important clinical implications in the treatment of patients undergoing cardiac arrest and CPR.

Analysis of Variance↗
PubMed1992

Evaluation and comparison of the adverse effects of streptokinase and alteplase.

The frequency and severity of adverse effects resulting from the administration of streptokinase and alteplase were determined in 126 consecutive patients who received standard dosages of these agents for the treatment of acute myocardial infarction. Evaluation was based on patient assessment by nursing staff, physicians, and the investigators before, during, and after thrombolytic administration. Overall, adverse effects occurred in 15 (41.7%) of 36 patients receiving streptokinase and 12 (13.3%) of 90 receiving alteplase (p = 0.001). No major bleeding or neurologic events were documented. Minor bleeding occurred in 13.9% and 7.8% of streptokinase and alteplase recipients, respectively (p = 0.47), and hypotension in 8 (22.2%) and 5 (5.6%), respectively (p = 0.01). The frequency of hypotension associated with streptokinase was significantly higher than that with alteplase. Thrombolytic-induced hypotension was easily managed and was not associated with sequelae.

Adult↗
PubMed1991

The effect of CPR on plasma diltiazem concentrations in dogs.

STUDY OBJECTIVE: To determine the effect of cardiac arrest with CPR on diltiazem concentrations in dogs. DESIGN: Prospective, double-blind, randomized trial. SETTING: Laboratory at a large university-affiliated medical center. TYPE OF PARTICIPANTS: Twenty mongrel dogs. INTERVENTIONS: Following administration of anesthesia, catheters were placed in the pulmonary artery, aortic arch, left ventricle, and right ventricle. Dogs were randomized to receive diltiazem (0.5 mg/kg) either 60 minutes before or during cardiac arrest with CPR. After 13 minutes of cardiac arrest, defibrillation was attempted. MEASUREMENTS AND MAIN RESULTS: Frequent blood samples for diltiazem concentrations were obtained before, during, and after cardiac arrest. The mean diltiazem concentration rose 70% during CPR in the group that received diltiazem before cardiac arrest. The group that received diltiazem during CPR had concentrations five times greater than expected during sinus rhythm. CONCLUSION: Increased diltiazem concentrations are observed during CPR and are probably related to altered distribution encountered during CPR.

Animals↗
PubMed1989

Differences in systemic and myocardial blood acid-base status during cardiopulmonary resuscitation.

Simultaneous arterial (aortic), mixed venous (pulmonary artery), and myocardial venous (great cardiac vein) blood gas and lactate concentrations were obtained in 12 dogs before and during cardiac arrest and CPR. We observed marked mixed venous and myocardial venous acidosis and increased PaCO2 but normal pHa and reduced PaCO2. Furthermore, the pH was significantly lower and the PCO2 significantly higher at the myocardial venous site compared to the mixed venous site, and marked myocardial lactate production occurred during CPR. Calculated bicarbonate and CO2 content (CCO2) did not increase during CPR from any site compared to control values and actually decreased significantly in arterial and myocardial venous samples. Changes in hydrogen ion concentration in both mixed venous and myocardial venous blood correlated with changes in lactate concentration but not total CCO2. Our results during CPR demonstrate a) a significant discrepancy between arterial and mixed venous blood gases but also a large and significant discrepancy between mixed venous and myocardial venous blood gases, b) significant anaerobic systemic and myocardial metabolism, and c) that mixed venous and myocardial venous acidosis is possibly a result of lactic acidosis.

Acid-Base Equilibrium↗
PubMed1989

Epinephrine versus methoxamine in survival postventricular fibrillation and cardiopulmonary resuscitation in dogs.

Previous studies have indicated that methoxamine (an alpha adrenergic receptor agonist) may provide an advantage compared to epinephrine (a mixed alpha and beta adrenergic agonist) during cardiac arrest and CPR. To test this theory, we compared the effects of bolus injections of epinephrine vs. methoxamine on survival, hemodynamic variables, blood gases, and blood lactate concentrations during ventricular fibrillation and CPR in 12 dogs. Each dog underwent a 3-min fibrillatory arrest followed by 10 min of fibrillation and CPR, at which time the animals were defibrillated. Epinephrine (0.05 mg/kg, n = 6) or methoxamine (2 mg/kg, n = 6) was administered at the start of CPR. Both epinephrine and methoxamine produced identical survival rates (5/6) with no differences in coronary perfusion pressure gradients or blood gases (aortic, venous, or great cardiac venous pH, PaO2, or PaCO2) during CPR. Also, there were no differences between the two study groups in myocardial lactate or oxygen extraction ratios during CPR. We conclude that in the dosages tested in our experimental model, epinephrine and methoxamine produce similar results in the variables which we measured.

Animals↗
PubMed1988

Antifibrillatory effects of high dose bretylium and a lidocaine-bretylium combination during cardiopulmonary resuscitation.

Previous CPR studies from our laboratory have shown that a standard iv dose of lidocaine (2 mg/kg) has a rapid antifibrillatory effect, while a standard dose of bretylium (5 mg/kg) produces a delayed but more pronounced effect. In order to determine the optimal doses, we investigated the antifibrillatory effects of a) high dose bretylium (10 mg/kg) and b) a combination of lidocaine (2 mg/kg) and bretylium (5 mg/kg) during CPR in two groups of anesthetized dogs. Ventricular fibrillation threshold (VFT) was determined using a train method and CPR was performed by a pneumatic device. During both a control and drug phase, the VFT was determined in each dog before CPR, and after each of three consecutive 3-min CPR periods. The combination of lidocaine and bretylium (11 dogs) caused a significant increase in VFT compared to the control phase after each of the 3-min CPR periods and maintained this effect for greater than 2 h. Bretylium 10 mg/kg (eight dogs) significantly elevated the VFT only after the third 3-min CPR period. We conclude that the combination of standard doses of lidocaine and bretylium produces a rapid and prolonged antifibrillatory effect and may be the optimal regimen in the CPR setting. High dose bretylium has a delayed onset of effect and appears to produce no greater effect than standard doses of the drug.

Animals↗
PubMed1988

Combination high dose amrinone and dopamine in the management of moribund cardiogenic shock after open heart surgery.

Two patients who suffered severe cardiogenic shock after open-heart surgery were successfully resuscitated with high doses of amrinone and dopamine. Both patients had required cardiopulmonary resuscitation and neither was responsive to more conventional mechanical and pharmacologic intervention. Neither patient suffered any serious side effects and both were eventually discharged from the hospital in good condition. These two case reports suggest the potential for using higher than previously reported doses of amrinone in combination with dopamine for the successful treatment of moribund cardiogenic shock in the post open-heart surgical patient. Further studies are needed to assess whether this high-dose drug combination will be successful in patients who present with severe cardiogenic shock unrelated to the post open-heart surgical setting.

Aged↗
PubMed1986

Epoprostenol sodium (prostacyclin) infusion in acute myocardial infarction.

Epoprostenol (prostacyclin) is a potent inhibitor of platelet aggregation and causes relaxation of vascular smooth muscle. These effects may be beneficial in patients with acute myocardial infarction. The effect of epoprostenol infusion in patients with acute myocardial infarction was evaluated in a randomised double blind study of 45 patients with evidence of myocardial infarction of less than 16 hours' duration. The patients were given a 72 hour infusion of epoprostenol (23) or placebo (22). The maximum dose was 5 ng/kg/min. The mean time to treatment was 8.3 hours (range 3.8-15.9 hours). The mean dose was 4.9 ng/kg/min. The patients were followed until day 30. No significant differences were found between the groups in mortality, development of congestive heart failure, cardiogenic shock, arrhythmias, recurrent chest pain, reinfarction, peak creatine kinase concentration, or the time taken to attain peak creatine kinase concentration. No significant difference in baseline ejection fraction was noted between groups, and no significant change in ejection fraction occurred within each group or between groups. The only significant side effect was the development of facial flushing in the epoprostenol group. In this pilot study epoprostenol was well tolerated by patients with acute myocardial infarction. No benefit from epoprostenol could be demonstrated at the dose range used when the drug was administered within 16 hours of the onset of symptoms.

Adolescent↗
PubMed1986

The effect of lidocaine and bretylium on the defibrillation threshold during cardiac arrest and cardiopulmonary resuscitation.

The effect of intravenous lidocaine, 2 mg/kg, and bretylium, 5 mg/kg, on defibrillation threshold (DFT) was investigated in alpha-chloralose anesthetized dogs undergoing conventional closed chest cardiopulmonary resuscitation (CPR) following induced ventricular fibrillation. Ventricular fibrillation was induced electrically and CPR was performed by a pneumatic device set to compress the chest 60 times and inflate the lung 12 times a minute. Defibrillation was achieved using underdamped sinusoidal current shocks from a special defibrillator which allowed determination of delivered energy. The DFT was defined as the peak current which defibrillated, but no more than 20% higher than a current which did not defibrillate. All DFTs were obtained within 5 min of CPR. The mean +/- SD current and energy thresholds required for defibrillation during lidocaine-CPR (seven dogs) were 17.0 +/- 8.9 A and 53.0 +/- 40.7 J as compared to 12.5 +/- 6.2 A and 34.3 +/- 30.7 J, respectively during control-CPR (P less than 0.05). The mean +/- SD current and energy thresholds during bretylium-CPR were 11.0 +/- 3.4 A and 24.1 +/- 1.3 J as compared to 11.8 +/- 1.7 A and 29.4 +/- 9.6 J, respectively, during control-CPR (NS). These results show that lidocaine acutely elevated defibrillation threshold whereas bretylium did not produce such an effect. The effect on DFT along with other pharmacologic properties should be considered when lidocaine or bretylium is used in the setting of cardiac arrest and CPR.

Animals↗
PubMed1979

Gas pocket causing pacemaker malfunction.

Pacemaker malfunction was attributed to the increase in impedance to current flow caused by a pocket of air separating the anodal contact plate of a unipolar generator from the overlying skin. Lack of capture was noted 20 hours after implantation. The malfunction was permanently corrected by bedside aspiration of the gas with a sterile syringe.

Air↗
PubMed1978

Phantom pacemaker programming.

Spurious or "phantom" programming of programmable pacemakers may occur as the result of two phenomena. One is change in rate and/or output of the generator from an anomalous source (dysprogramming); the other is a generator response different from that intended and set on the conventional programmer (misprogramming). In either case, the result is a nuisance, at best. Conceivably, at worst, an irreversible subthreshold output could be induced. Despite wide usage of such devices, neither event has been reported. In the routine follow-up of 95 implanted Cordis Omni-Stanicor generators, we have observed three instances of dysprogramming upon application of a magnet commonly used to induce the asynchronous mode. Subsequent in vitro studies revealed magnetically induced programming reed switch vibration in 9 of 6,680 units, which could account for the in vivo observations. We also describe many instances of misprogramming, attributable, in most cases, to a faulty programmer emission count. In this series, none of the anomalies was clinically detrimental. However, anyone involved in pacemaker follow-up should be alerted to the existence of these potentially hazardous phenomena.

Cardiac Pacing, Artificial↗
PubMed1978

Clicks due to Swan-Ganz catheter.

Nonejection systolic and diastolic clicks appeared when a Swan-Ganz catheter was positioned in the proximal portion of the right pulmonary artery. The clicks disappeared on inflation of the catheter's balloon. Initial impressions included secondary prolapse of the mitral leaflets, an accentuated third heart sound, and the exposure of an occult opening snap. These high-frequency sounds are thought to be generated by the forward and backward movement of the catheter against either the proximal portion of the pulmonary artery or the right ventricular outflow tract or by a whipping action of the catheter itself.

Cardiac Catheterization↗
PubMedDate not supplied

The effect of quinidine sulfate on QRS duration and QT and systolic time intervals in man.

QRS duration, QT interval, total electromechanical systole (QS(2)), left ventricular ejection time (LVET), and preejection period (PEP) were determined in five male and two female healthy volunteers in a fasting state at hourly intervals for 7 hours during a control period and after administration of 400 mg quinidine sulfate. Changes of QRS duration (delta QRS) and rate-corrected QT interval (delta QTc) were calculated before and after quinidine. Deviations of measured QS(2), LVET, and PEP from the normal were calculated as the differences between the observed interval and those predicted from the normal regression equation. The effect of quinidine on systolic time intervals (delta QS(2), delta LVET, DELTA PEP) were expressed as the differences between the deviations from the normal regression equation during the control period and after the drug administration. After quinidine sulfate delta QRS, delta LVET, delta PEP, and delta PEP, delta LVET were slight and inconsistent. However, delta QTc and delta QS(2) were significant (at P is less than 0.05 or better) from the first hour to the 7th hour and from the 2nd hour to the 5th hour, respectively. The mean maximum delta QTc was 44.8 milliseconds and delta QS(2) was 29.9 milliseconds. The significant changes of QTc and QS(2) seemed to occur at the plasma level range of 0.75-1.9 mug/ml. This study indicates that of the various systolic time interval measurements obtained after quinidine administration, the changes of QT interval and QS(2) are most significant and that these changes seem to occur even at low plasma levels.

Adult↗