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Biomedical subjects

W C Dalsey

Publications and source records attributed to W C Dalsey.

At least 37 records · Page 2Linked to original sources
PubMed1997

Alkalinization is ineffective for severe hyperkalemia in nonnephrectomized dogs. Hyperkalemia Research Group.

OBJECTIVE: To determine whether alkalinization with sodium bicarbonate (NaHCO3) in near-lethal hyperkalemia either lowers potassium (K) rapidly or shortens duration of cardiac conduction disturbances. METHODS: A controlled canine laboratory investigation of 3 treatments for severe hyperkalemia. Conditioned dogs (n = 8; 17-30 kg) received, in random order, 2 mmol/kg of each of 3 treatments (matched in sodium and water) in separate experiments > or = 1 week apart: 1.05% NaHCO3 over 60 minutes (infusion therapy); 8.4% NaHCO3 over 5 minutes, then 14 mL/kg sterile water over 55 minutes (bolus therapy); 8.4% NaCl over 5 minutes, then 14 mL/kg sterile water over 55 minutes (saline therapy). Prior to administering one of the above therapies, the animals were anesthetized with 0.5-2.5% isoflurane and ventilated to maintain a normal PCO2. After 30 minutes of equilibration, 2 mmol/kg/hr (loading dose) of a 2-mmol/mL KCl solution was given until idioventricular or relative junctional bradycardic dysrhythmias were sustained for 15 minutes. Then KCl was decreased to 1 mmol/kg/hr (maintenance dose) for 2 hours and 45 minutes. Treatment was begun after 45 minutes of maintenance KCl infusion. RESULTS: The pretreatment K level (all studies) was 9.06 +/- 0.82 mmol/L (mean +/- SD). Although the mean K level decreased more after saline therapy than after bolus therapy at every time, differences were neither statistically significant nor clinically important during the first 30 minutes. The means of the differences in decreases (saline minus bolus) were small, 0.26 (95% CI, -0.48 to 1.00) at 15 minutes, 0.16 (95% CI, -0.67 to 0.98) at 30 minutes. Dysrhythmia duration was shorter with bolus therapy than for saline therapy in only 1 of 5 dogs (p = 0.38). CONCLUSIONS: Hypertonic saline bolus lowered plasma K as effectively as NaHCO3 bolus in this animal model within the first 30 minutes. Clinically meaningful decreases due to alkalinization alone within 30 minutes are unlikely.

Animals↗
PubMed1992

Steroids for the treatment of corrosive esophageal injury: a statistical analysis of past studies.

Caustic esophageal injury causes substantial morbidity and mortality. However, the use of corticosteroids to treat this problem has been evaluated in a limited number of studies because adequate sample size is difficult to obtain. We analyzed 361 subjects with corrosive esophageal injury derived from 10 retrospective and three prospective publications. We divided cases into those treated with corticosteroids and antibiotics (T) and those that received neither modality (NT) based on inclusion and exclusion criteria. Forty-one percent of NT cases developed esophageal stricture and 19% of T cases developed this complication (P less than .01). There were no reported strictures among 72 first-degree esophageal burns (combined T and NT cases). The T group contained 54 strictures among 228 patients (24%) with either second- or third-degree burns. The NT group of 25 patients with the same burn severity suffered 13 strictures (52%) (P less than .01). Reports of death and gastrointestinal hemorrhage did not increase among steroid-treated patients. We do not recommend corticosteroid therapy for first-degree esophageal injuries. However, this therapy may be useful in preventing strictures among patients with second- or third-degree corrosive esophageal burns.

Adult↗
PubMed1992

The mangled extremity. Compartment syndrome and amputations.

Injuries that amputate, crush, or otherwise mangle an extremity are devastating. The possibilities of medical and psychologic disability, multiple operations, and protracted rehabilitation loom before these patients. Fortunately, expert care given by the emergency department physician maximizes the opportunity for success should the limb be replanted or revascularized. The first priority for the emergency department staff is the efficient and aggressive resuscitation of the patient. Only after this has been carried out and other life-threatening injuries addressed can attention be directed toward the injured limb. It is in the patient's best interest if the emergency department staff assumes that a mangled extremity will be replanted or revascularized. Advances in microsurgical technique and equipment have enabled surgeons to achieve salvage rates greater than 90%. Continued improvements in technique, equipment, rehabilitation, and patient selection will enable more patients to benefit from limb salvage procedures.

Amputation, Traumatic↗
PubMed1991

Prehospital transcutaneous cardiac pacing for symptomatic bradycardia.

We studied patients with symptomatic bradycardia to determine the importance of presenting hemodynamic status and prehospital transcutaneous cardiac pacing (TCP) upon patient survival. Of 51 patients with witnessed cardiovascular decompensation and initial bradycardia, 27 (53%) received TCP. There were no significant differences between the paced patients and those without TCP for mean times from collapse until cardiopulmonary resuscitation, paramedic arrival and a paceable rhythm, or from paramedic arrival until a paceable rhythm. Overall, emergency department arrival with a palpable pulse (26% in paced vs 13% in nonpaced group; P = 0.20) and survival to hospital discharge (15% in paced vs 0% nonpaced group; P = 0.07) tended to be better for the paced group. No patient without a palpable pulse on paramedic arrival survived to leave the hospital. Of patients with a palpable pulse upon paramedic arrival, survival to hospital discharge was greater for the paced group (80% in paced vs 0% in nonpaced group; P = 0.024). TCP appears to be most beneficial in those patients with bradycardia who have a palpable pulse when first seen.

Aged↗
PubMed1990

Aerobic bacteria cultured from the mouth of the American opossum (Didelphis virginiana) with reference to bacteria associated with bite infections.

The American opossum inflicts bite injuries both when hunted for food and when accidentally provoked when handled in captivity. This study involved aerobically culturing organisms from the mouths of seven wild opossums (Didelphis virginiana). Isolates included streptococci, coagulase-positive and -negative staphylococci, Aeromonas spp., Citrobacter freundii, Eikenella corrodens, and Escherichia coli.

Animals↗
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

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↗
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

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

Central versus peripheral intravenous routes in cardiopulmonary resuscitation.

The central venous (CV) and peripheral venous (PV) routes of drug administration are generally considered to be equally effective during cardiopulmonary resuscitation (CPR). This canine study compared simulated drug delivery via CV and PV routes during CPR. The CV group dogs had a CV catheter placed via the external jugular vein, and the PV group dogs had a PV catheter placed in the distal forelimb. Thirty seconds after the induction of cardiac arrest with KCl, CPR was begun with a gas-powered chest compressor with ventilations after every fifth compression. Sixty seconds later, a 0.5 ml bolus of technetium 99m-labeled serum albumin was given. Time activity curves were obtained over the right and left ventricles. The mean time for the counts to rise to half the left ventricular peak (T1/2LV) was significantly less for the CV group than for the PV group (P less than 0.05), averaging 11 and 84 seconds, respectively. The time to left ventricular peak (TLV) was also statistically shorter for the CV group than the PV group, averaging 118 versus 258 seconds, respectively. This study demonstrates that central venous administration is more rapid than peripheral venous administration during CPR and supports the preferential use of the central venous route for drug administration clinically.

Animals↗
PubMed1984

Compartmental pressure measurements during application of the pneumatic antishock garment.

Recent case reports have implicated the pneumatic antishock garment (PASG) in the development of the compartment syndrome in the lower extremities. The present study used the anterolateral compartment of the canine hindlimb to model the effect of the PASG on tissue pressure within the compartment (Pc). Prior to inflation of the garment, baseline Pc was 5.3 mm Hg. PASG inflation to 60 mm Hg for 20 minutes resulted in an increase in Pc of 75.0 mm Hg over baseline values. The rise in Pc was reduced significantly following hemorrhage of the animal, measuring 65.8 mm Hg at a mean arterial pressure of 70 to 80 mm Hg and 62.5 mm Hg at a mean arterial pressure of 40 to 50 mm Hg. In the immediate postarrest state, Pc rise after a five-minute inflation of the garment was 57.5 mm Hg. In all cases, Pc promptly returned to baseline values when the PASG was deflated, and there was no significant change in Pc following deflation of the garment under conditions of normotension, hemorrhagic hypotension, and in the immediate postarrest state. Our results suggest that the level of arterial pressure may contribute to Pc rise during PASG inflation.

Animals↗
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↗