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S A Syverud

Publications and source records attributed to S A Syverud.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effects of dichloroacetate administration during fatal hemorrhagic shock in immature swine.

During hemorrhagic shock, decreased perfusion and poor tissue oxygenation lead to increased lactate production. Previous animal studies have suggested that sodium dichloroacetate (DCA), an agent that decreases lactate production, can improve hemodynamics and survival when administered after severe hemorrhage. We used an unanesthetized porcine hemorrhagic shock model to assess the effect of DCA on survival time when administered during fatal hemorrhage. Immature female swine weighing 14 to 20 kg were splenectomized and instrumented with chronic indwelling aortic and right atrial catheters one week prior to hemorrhage. On the day of the experiment, the unanesthetized animals' aortic catheter was connected to a roller pump and blood was removed at a rate of 1.0 mL/kg/min until death occurred. Experimental animals (n = 8) received sodium dichloroacetate (25 mg/mL distilled water) 100 mg/kg IV bolus beginning 15 minutes after the start of hemorrhage followed by a 3 mg/kg/min constant IV infusion. Control animals (n = 8) received an equal volume of normal saline. Arterial pressure, heart rate, blood gases, serum lactate, and serum glucose were measured at baseline and every 15 minutes during hemorrhage. There were no significant differences in survival time (controls, 63 +/- 2.8 min; DCA-treated, 60 +/- 3.7 min), lactate levels, or blood pressures between the two groups. These results suggest that DCA does not decrease serum lactate or improve survival time when administered during ongoing severe hemorrhagic shock. Further study should be directed at the effects of DCA as an adjunctive treatment after hemorrhage has been controlled and tissue perfusion restored.

Acetates↗
PubMed1987

Prehospital trial of emergency transcutaneous cardiac pacing.

A prospective alternate-day controlled trial of prehospital transcutaneous cardiac pacing (PACE) of hemodynamically significant bradycardia and asystole was undertaken. All patients had a Glasgow coma scale score of 12 or less. Patients in the control group (n = 101) received standard advanced cardiac life support (ACLS) care. Patients in the pacing group (n = 101) were to receive PACE in addition to standard ACLS treatment; 89 patients were actually paced. The two groups were comparable in terms of age, sex, presenting rhythm, and mean times to cardiopulmonary resuscitation (CPR) and ACLS. For the 144 patients in whom the time of arrest could be estimated, the mean times to CPR and ACLS were 5.3 +/- 4.0 and 10.9 +/- 7.1 min, respectively. For the 65 paced patients in whom the time of arrest could be estimated, the mean time from arrest to pacing was 21.8 +/- 8.8 min (range 2 to 43). Multivariate analysis of outcome variables (presentation to emergency department with a pulse, admission to the hospital, and discharge from the hospital) revealed that an initial rhythm of ventricular tachycardia or fibrillation and a short time to ACLS were correlated with a favorable outcome (p less than .05; logistic regression analysis). A short time to PACE was associated with admission to the hospital (p = .20; logistic regression analysis). The use of a stand-alone transcutaneous pacing device in the prehospital arrest setting was associated with generally long times until pacing and did not appreciably improve outcome. Use of PACE in patients demonstrating prehospital bradycardia without neurologic impairment remains to be evaluated.

Adult↗
PubMed1986

Hemodynamic effects of naloxone in anaphylactic shock.

Recent reports suggest that endorphins may contribute to hemodynamic depression in septic and hemorrhagic shock. There is also evidence that reversal of endorphin effects with high dose naloxone may improve hemodynamic function and improve survival in shock states. The purpose of this study was to examine the effects of naloxone on hemodynamic parameters in anaphylactic shock. Anaphylactic shock was induced in sensitized rabbits with horse serum. Three minutes after serum challenge, rabbits were treated with a 3 mg/kg bolus of naloxone followed by a 3 mg/kg per h infusion (group I, n = 8), or by injection with an equal volume of saline (group II, n = 8). Cardiac output, blood pressure, heart rate and body temperature were monitored continuously for 60 min and the experiment was terminated. There was a significant increase in cardiac index in group I animals at 10 min (P less than 0.01) and 15 min (P less than 0.01). Stroke volume index was also higher in naloxone treated animals at 10 min and 15 min (P less than 0.05). Although mean blood pressure was higher in group I animals at all time intervals after naloxone was begun, the difference was statistically significant only at 60 min (P less than 0.05). Peripheral vascular resistance index was not significantly different for the two groups.

Anaphylaxis↗
PubMed1986

Dantrolene sodium for treatment of heatstroke victims: lack of efficacy in a canine model.

Dantrolene sodium, a skeletal-muscle relaxant known to be effective for treatment of malignant hyperthermia, was evaluated for efficacy in treatment of heatstroke. Non-exertional heatstroke was induced in 11 dogs by external heating following barbiturate anesthesia. When core temperature reached 43 degrees C (109.4 degrees F) heating was discontinued and control animals (n = 6) were allowed to cool passively in room air. Treatment animals (n = 5) received 5 mg/kg dantrolene sodium intravenously at the start of room-air cooling. Serial temperatures (pulmonary arterial, rectal, cerebral, and subcutaneous), blood chemistry tests (including electrolytes, liver enzymes, and complete blood count), and hemodynamic parameters (including cardiac output, arterial pressure, and urinary output) were followed for 12 hours after induction of heatstroke. Autopsies, including gross and microscopic examination, were performed on all animals. Dantrolene administration did not significantly affect cooling rates, hemodynamic parameters, pathological changes, or clinical outcome. Statistically significant changes in urinary output and serum creatinine observed in the first hours after dantrolene administration can be attributed to the mannitol vehicle in which the drug was delivered. There were no statistically significant differences in these values at 12 hours. Dantrolene sodium does not appear to enhance passive cooling in treatment of non-exertional canine heatstroke.

Animals↗
PubMed1986

Hemodynamics of transcutaneous cardiac pacing.

Transcutaneous cardiac pacing has recently been rediscovered as a rapid means of initiating emergency cardiac pacing. Potential myocardial injury from extended transcutaneous pacing could adversely affect cardiac hemodynamics during pacing. This canine study compares the hemodynamics of transcutaneous and transvenous cardiac pacing in animals with induced chronic heart block. One to two weeks following chemical ablation of the His bundle, hemodynamic measurements were made during 60 minutes of transcutaneous and 5-minute periods of conventional right ventricular endocardial pacing. Cardiac index and output were found to increase significantly (P less than 0.005), and systemic vascular resistance was found to decrease significantly (P less than 0.005) from baseline values with both pacing techniques. A hemodynamic difference between pacing techniques was evident only for mean arterial blood pressure; pressure measurements during transvenous pacing were slightly greater than those during transcutaneous cardiac pacing. The hemodynamic measurements were found to be stable during a 60-minute period of transcutaneous cardiac pacing. This study demonstrates that transcutaneous cardiac pacing is as effective hemodynamically as conventional transvenous pacing in animals with induced chronic heart block.

Animals↗
PubMed1986

Transcutaneous and transvenous cardiac pacing for early bradyasystolic cardiac arrest.

Emergency transcutaneous cardiac pacing was studied prospectively in 19 patients presenting to the emergency department with a bradyasystolic cardiopulmonary arrest of 20 minutes duration or less. Pacing was initiated when conventional advanced cardiac life support (including atropine administration) and a fluid challenge failed to restore a pulse. Seventeen patients also had placement of transvenous pacemaker electrodes for cardiac pacing. Transcutaneous cardiac pacing rapidly established a blood pressure in the two patients who for clinical reasons did not receive a transvenous pacemaker. Five patients were transcutaneously paced within five minutes of cardiac arrest (Group 1) and the remaining 14 were paced between five and 20 minutes following cardiac arrest (Group 2). Two of the Group 1 patients were admitted and subsequently recovered full neurological and prearrest cardiac function. Fewer Group 2 patients developed a blood pressure (P = .04), and there were no patients with full neurologic recovery in this group (P = .06). Similar results were found for transvenous cardiac pacing; there was a greater incidence of a palpable pulse and measurable blood pressure (P = .05 for both) in the Group 1 patients than in the Group 2 patients. No difference in clinical outcome was noted between the two pacing techniques. These results support the concept that cardiac pacing must be initiated early if the outcome of bradyasystolic cardiac arrest is to be altered.

Aged↗
PubMed1986

Radiologic assessment of transvenous pacemaker placement during CPR.

During an 18-month period we prospectively studied 36 emergency department patients who had a transvenous pacing catheter placed without fluoroscopic or ECG guidance during closed-chest massage. Transvenous pacing was instituted at a mean elapsed time of 35 minutes (range, ten to 80 minute) after the onset of cardiac arrest, including prehospital and ED care times. Catheter tip position was assessed using postresuscitation or postmortem chest radiographs. Pacing catheters were fixed in the position of electrical capture prior to radiographs; when capture was never achieved, the catheter was fixed at 35 cm from the point of insertion. Position of the catheter tip on radiographs was as follows: right ventricle, ten of 36 patients; right atrium, 18 of 36; and other location, eight of 36. Ectopic catheter tip positions included inferior vena cava (four), pulmonary artery (one), hepatic vein (two), and internal jugular vein (one). Catheter tip position within the right ventricle correlated with a significantly higher incidence of electrical capture when compared with other catheter tip locations (P less than .004). There was a significantly higher incidence of successful placement into the right ventricle when an internal jugular, rather than a subclavian venous, access route was used (P less than .004). Only one of 36 patients was resuscitated successfully; none lived to be discharged from the hospital. Misplacement of the catheter tip may contribute to the poor success rate of transvenous pacing during CPR. The internal jugular vein may be the access site of choice when transvenous pacing is attempted during chest compressions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

High-frequency jet ventilation cooling in a canine hyperthermia model.

A study was undertaken to evaluate high-frequency jet ventilation (HFJV) as an adjunct for the treatment of heatstroke. Eleven mongrel dogs were anesthetized, shaved, and externally heated until core temperature reached 43 C (109.4 F). Control animals (n = 6) were cooled passively in room air. Treatment animals (n = 5) were cooled with the addition of HFJV using a flow-interrupter, high-frequency jet ventilator with a rate of 200, a driving pressure of 40 psi, and an inspiratory to expiratory ratio of .5 to deliver room air. Temperatures were measured in brain, pulmonary artery, rectum, and subcutaneous tissue of the chest wall. Serial arterial blood gases, cardiac outputs, and mean arterial pressures were measured at baseline, maximal heating, and at .5, 1, 2, and 12 hours after heating. Animals were sacrificed 12 hours after heatstroke induction. Cooling rates for brain, pulmonary artery, and rectum achieved in the HFJV group were 1.7 times faster than those for the control group (P less than .05), although slower than previously reported cooling rates with gastric and peritoneal lavage. A higher PO2, a lower PCO2, and a more physiologic pH was maintained in the HFJV group than in the control group at 30 and 60 minutes after onset of cooling (P less than .05). Gross and histopathologic examination showed characteristic changes of heatstroke in both groups; no deleterious findings could be attributed to the use of HFJV itself. HFJV warrants clinical investigation as an adjunct for treatment of hyperthermia.

Animals↗
PubMed1985

Pathological aspects of transcutaneous cardiac pacing.

Although electrical energy has the potential to produce myocardial injury, the risk of tissue damage from transcutaneous cardiac pacing is largely unknown. This study reports the anatomical findings of a canine transcutaneous stimulation study. Ten dogs had 100-mA, 20-msec (pulse duration), transcutaneous impulses delivered across the thorax for 30 minutes at a rate of 80 stimuli per minute. Seventy-two hours later the animals were sacrificed, and the heart, lungs, and tissues of the chest wall were examined for pathological changes. Gross and microscopic lesions consistent with electrically induced myocardial damage were found in all hearts examined. These lesions included myocardial pallor and focal myofibril coagulation necrosis in the right ventricular outflow tract and perivascular microinfarcts in the posterior left ventricular myocardium. These lesions were not extensive; less than 5% of the right ventricular free wall and less than 1% of the left ventricular posterior wall were involved. Lesions of this extent would not be expected to cause clinically detectable changes in cardiovascular status. Short-term use of transcutaneous pacing appears to be safe. Determination of the potential for clinically significant injury with long-term use requires further study.

Animals↗
PubMed1985

Bicarbonate therapy for the cardiovascular toxicity of amitriptyline in an animal model.

The beneficial hemodynamic effects of sodium bicarbonate as treatment for tricyclic antidepressant poisoning were investigated in an animal model. Seven adult dogs (17.5 to 20 kg) were poisoned by an intravenous infusion of amitriptyline. Toxicity was defined as a doubling of the initial QRS width. A continuous infusion was used to maintain toxicity for 30 minutes after which 44.5 mEq of sodium bicarbonate was administered intravenously. Five of the animals survived to completion of the experiment. Three of the surviving animals developed dysrhythmias. All dysrhythmias ceased within one minute of administration of sodium bicarbonate. An increase in mean blood pressure (P less than .05) and serum pH (P less than .05) and a decrease in mean QRS width (P less than .05) occurred following administration of sodium bicarbonate. The maintenance of toxicity for 30 minutes suggests that this model can be used for future studies of tricyclic antidepressant poisoning.

Amitriptyline↗
PubMed1985

Iced gastric lavage for treatment of heatstroke: efficacy in a canine model.

This study was undertaken to evaluate a central cooling technique for heatstroke, gastric lavage with iced tap water, for speed of cooling and efficacy of treatment in an anesthetized canine heatstroke model. Eleven mongrel dogs were anesthetized, shaved, and externally heated until core temperature reached 43.0 C (109.4 F). Control animals (n = 6) were cooled passively in room air. Treatment animals (n = 5) were cooled with the addition of gastric lavage with iced tap water through a large-bore orogastric tube. Temperatures were monitored using thermocouples in the brain, pulmonary artery, rectum, and subcutaneous tissue of the chest wall. Serial enzymatic and hematologic laboratory studies and hemodynamic parameters were measured prior to heating, at the end of heating, and at 0, 0.5, 1, 2, and 12 hours after heating. Animals were sacrificed 12 hours after heatstroke induction and gross and microscopic pathologic examination was performed. Central cooling rates achieved in the lavage group were five to six times faster than in the control group, (P less than .01) and are comparable with those reported in the literature for external cooling techniques. No significant complications were induced by tap water lavage. Rapid cooling in the lavage group resulted in a statistically significant improvement in serum creatinine and LDH after heatstroke induction (P less than .05). Gastric lavage with iced tap water appears to be an effective alternative or adjunctive cooling technique for heatstroke in the dog.

Animals↗
PubMed1985

A hemodynamic model for anaphylactic shock.

The treatment of cardiovascular collapse and anaphylactic shock is largely empiric. A simple animal model was developed to evaluate the hemodynamic alterations in anaphylaxis. Eight adult New Zealand white rabbits of both sexes were studied. All animals weighed 3.8 kg to 5.3 kg. Sensitization was accomplished with a 2-mL subcutaneous dose of horse serum followed in two days with a 2-mL intravenous (IV) dose. At least 14 days elapsed after the IV dose before a 1-mL challenge dose of horse serum was given. On the day of the challenge dose, a femoral arterial catheter, arterial temperature probe, and right atrial catheter were placed under methoxyflurane anesthesia. The temperature probe was positioned in the aortic arch. The methoxyflurane was discontinued and the only sedation given during the shock phase was IV diazepam (0.1 mg/kg to 0.5 mg/kg). At least 30 minutes after methoxyflurane was discontinued, the challenge dose of horse serum was given through the right atrial catheter. Before and during the shock phase cardiac rhythm, arterial pressure, and intravascular temperature were monitored continuously. Cardiac outputs (CO) were performed by a thermodilution technique using 0.8 mL room temperature saline injectate through the right atrial catheter. Temperature deflection of the aortic probe was recorded and cardiac output was calculated. After giving the challenge dose, CO was measured at three, five, ten, 15, 25, 35, 45, and 60 minutes. All eight animals showed a significant (P less than .0005) fall in CO, cardiac index, and blood pressure within three minutes. The fall in cardiac index was 50% or more in all animals. Two animals died as a result of shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylaxis↗
PubMed1985

Emergency department use of transcutaneous pacing for cardiac arrests.

Transcutaneous cardiac pacing is a rapid technique for pacing the heart using skin electrodes to pass repetitive electrical impulses through the thorax. This paper reports the results of transcutaneous pacing in a series of 52 emergency department patients. Patients were selected for pacing if they were unconscious and in asystole (30 patients) or unconscious with a pulseless or hemodynamically ineffective bradycardia (22 patients). In all cases, transcutaneous pacing was attempted after initial resuscitative drug therapy failed. Of the 26 patients with successful ECG capture, 14 were initially in asystole, 11 were initially in a pulseless bradycardia, and one had a hemodynamically ineffective bradycardia. Of the eight patients developing a pulse, four developed a measurable BP. The four patients who developed a measurable BP were young (ages 22 to 39 yr) and only one had an underlying cardiac etiology for his cardiac arrest. No patient survived to be discharged from the hospital. Twenty-five of the 52 patients also had a transvenous pacemaker inserted, with successful electrical capture in five of the patients. Only one of the transvenously paced asystolic patients subsequently developed a BP. There were no patients successfully paced transvenously who were not successfully paced transcutaneously.

Adult↗
PubMed1984

Developments in transcutaneous and transthoracic pacing during bradyasystolic arrest.

Transthoracic cardiac pacing historically has been relegated to the role of the technique of last resort in treating cardiac arrest. Recent studies have shown that this technique has a high rate of successful electrical capture, but often without mechanical activity. Survival rates have been shown to be dismal when the technique is used late in cardiac arrest. Results of several recent studies of patients paced by the transcutaneous technique have suggested that electrical capture can often be rapidly obtained in asystolic or pulseless bradycardic patients. Even though electrical capture can occur late in a cardiac arrest, the development of mechanical activity with survival is rare. Survivors generally have been treated early in their arrest and have had hemodynamically ineffective bradycardias. These findings suggest that rapid initiation of transcutaneous pacing in patients with Stokes-Adams attacks, increasing heart block associated with myocardial ischemia, postdefibrillation asystole, or pulseless bradycardia may improve survival. However, victims of a prolonged cardiac arrest whose myocardium has irreversibly ceased to function mechanically are unlikely to benefit from any pacing technique.

Cardiac Pacing, Artificial↗
PubMed1983

Transcutaneous cardiac pacing: determination of myocardial injury in a canine model.

Transcutaneous cardiac pacing holds promise as the initial cardiac pacing technique for emergency patients. Determination of the extent of myocardial injury associated with the use of commercial transcutaneous pacemaker devices has been limited. This study was undertaken to document electrocardiographic, enzymatic, and histologic changes following transcutaneous pacing. Ten mongrel dogs were paced with a transcutaneous cardiac pacemaker for 30 minutes. Electrical pulses of 100 mA lasting 20 ms each were delivered at a rate of 80/min via cutaneous electrodes on the anterior and posterior thorax. Myocardial damage was assessed by serial electrocardiograms (ECGs), serial creatine kinase (CK) determinations with myocardial band (MB) fractionation, and gross and microscopic pathologic examination. Double blind reading of the ECGs showed no significant changes after pacing. CK levels peaked an average of 78 units over baseline levels at 4 hours; however, there was no rise in the CK MB fraction. Pathologic examination revealed micro-infarcts adjacent to intramural vessels in 5 animals, but no clinically significant myocardial injury in the 10 dogs. The absence of enzymatic, cardiographic, and clinically significant pathologic findings was statistically significant (P less than .05). Transcutaneous pacing at low currents and for short periods appears to be a safe technique. This pacing technique deserves further evaluation, and may hold promise as a clinical tool during resuscitation.

Animals↗