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Biomedical subjects

K B Kern

Publications and source records attributed to K B Kern.

87 records · Page 5Linked to original sources
PubMed1986

The comparative pathology of open chest vs. mechanical closed chest cardiopulmonary resuscitation in dogs.

We compared the pathologic changes following open-chest cardiopulmonary resuscitation (OCCPR) vs. closed chest cardiopulmonary resuscitation (CCCPR) in 28 healthy mongrel dogs subjected to experimentally induced ventricular fibrillation (VF). VF was induced in 29 dogs. No treatment was given for 3 min, then mechanical CCCPR was given for the next 12 min. External defibrillation (80 joules) was then attempted twice. One dog was resuscitated. The remaining 28 dogs were divided into 2 groups of 14 each. Group A received continued CCCPR and group B received OCCPR. All dogs received advanced cardiac life support and were followed until resuscitated or dead. All dogs were autopsied and gross pathology scores and histopathology scores were determined for each animal, and for each of 19 separate tissues within each animal. The mean gross pathology scores for the following tissues were significantly greater for dogs that received OCCPR vs. those that received CCCPR: skin (3.4 vs. 1.2; P less than 0.001), subcutaneous tissue (3.7 vs. 0.6; P less than 0.001), chest wall muscle (3.7 vs. 0.5; P less than 0.001), and pleura (1.9 vs. 0.1; P less than 0.001). The mean total gross pathology score was also greater in dogs that received OCCPR vs. those that received CCCPR (17.2 vs. 7.7; P less than 0.001). The mean histopathology scores for the following tissues were significantly greater for dogs that received OCCPR vs. those that received CCCPR: skin (2.5 vs. 0.0; P less than 0.001), subcutaneous tissue (2.2 vs. 0.1; P less than 0.001), muscle (2.3 vs. 0.1; P less than 0.001), pleura (1.6 vs. 0.0; P less than 0.001), pericardium (1.4 vs. 0.2; P less than 0.01), epicardium (2.5 vs. 0.2; P less than 0.001), myocardium (2.5 vs. 0.3; P less than 0.001), and endocardium (1.9 vs. 0.5; P less than 0.01). The mean total histopathology score was also greater in dogs that received OCCPR vs. those that received CCCPR (20.1 vs. 7.4; P less than 0.001). The histopathology score for brain tissue was greater for the CCCPR group than for the OCCPR group (1.9 vs. 0.4; P less than 0.05). This study showed that OCCPR in dogs following VF caused more severe pathologic changes than CCCPR. These changes were attributed to thoracotomy-induced chest wall injury and to internal defibrillation induced myocardial injury. However, OCCPR caused less severe microscopic brain lesions than CCCPR.

Animals↗
PubMed1986

Neurologic outcome following successful cardiopulmonary resuscitation in dogs.

Successful cardiopulmonary resuscitation necessitates that both myocardial and central nervous system function be restored with minimal long-term damage. Recent resuscitation research has emphasized minimizing neurologic damage during and after cardiopulmonary resuscitation. However, whether neurologic damage is a major cause of death or morbidity following successful cardiopulmonary resuscitation is unknown. This study examined the role of neurologic injury as a cause for morbidity and mortality following cardiopulmonary resuscitation, and if parameters used successfully during resuscitation for assessing the potential for myocardial salvage, could also be used to predict neurologic outcome. Eighty-eight mongrel dogs underwent 3 min of untreated ventricular fibrillation and either 15 or 17 min of cardiopulmonary resuscitation. Twenty-four hour survivors were evaluated with a neurologic deficit scoring system. Thirty-one percent of these animals were never resuscitated. Twenty-eight percent were resuscitated, but expired prior to 24 h. Approximately half of those who expired after resuscitation died from apparent neurologic sequellae. Forty-one percent of the 88 animals survived for 24 h. Two-thirds of these survivors were completely neurologically normal, while one-third were neurologically impaired. Hemodynamic parameters useful in assessing cardiovascular prognosis were not helpful in predicting neurologic outcome. Hence, although the majority of resuscitated animals did not suffer neurologic damage, up to one-third did exhibit neurologic impairment following resuscitation. Neurologic injury is also a major contributor to early death following successful resuscitation. Hemodynamic parameters of cardiovascular recovery do not predict neurologic outcome after prolonged cardiopulmonary resuscitation.

Animals↗
PubMed1986

CPR-induced trauma: comparison of three manual methods in an experimental model.

Cardiopulmonary resuscitation (CPR) often results in traumatic injury to the patient. Differences in CPR-induced trauma among various forms of manual, external CPR, however, are unknown. We compared CPR-induced trauma among manual standard (STD) CPR at 60 compressions per minute; high-impulse compression (HIC) CPR at 120 compressions per minute; and interposed abdominal compression (IAC) CPR at 60 compressions per minute. A large (24 +/- 3 kg) mongrel canine model was used. Ten animals were assigned to each type of CPR. Each received 17 minutes of CPR, applied to produce the best possible coronary perfusion pressure without obviously damaging the dog. Defibrillation was attempted at 20 minutes. Necropsy was performed at the time of death or after sacrifice at 24 hours. Careful postmortem examination of the thorax, lungs, heart, abdomen, and great vessels was performed. A semiquantitative trauma score of 0 to 5 was assigned to each area with a possible maximal score of 25. There was no difference in trauma scores among STD (6.4 +/- 1.5), HIC (9.4 +/- 1.4), and IAC (8.1 +/- 1.3) methods. No significant correlation was found between the method of CPR and the different types of trauma. Specifically, IAC did not produce an increase in liver lacerations nor did HIC produce a significant increase in thoracic or pulmonary injuries. Six of 20 initially resuscitated animals expired during the 24-hour follow-up period due to CPR-induced injuries. Four of these six had extensive pulmonary trauma, including pulmonary hemorrhage or edema. Liver lacerations were the second most lethal injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1986

Twenty-four hour survival in a canine model of cardiac arrest comparing three methods of manual cardiopulmonary resuscitation.

Two new modifications of manual cardiopulmonary resuscitation, high impulse compression at a rate of 120/min and interposed abdominal compression at a rate of 60/min, have been reported to produce better hemodynamic responses than standard cardiopulmonary resuscitation at 60/min. However, the effect of these two new methods on initial resuscitation success and 24 hour survival is unknown. In this study, 30 mongrel dogs were divided into three equal groups, each treated with one of three types of manual cardiopulmonary resuscitation. Ventricular fibrillation was induced electrically in morphinized, endotracheally intubated dogs emerging from halothane anesthesia. After 3 minutes of circulatory arrest without intervention, one of the three techniques of manual cardiopulmonary resuscitation was begun, and continued for 17 minutes. Defibrillation was performed at 20 minutes. Successful resuscitation was defined as a mean arterial blood pressure of at least 60 mm Hg, without chest compressions, 10 minutes after the initial defibrillation attempt. Intensive care was provided for 2 hours, including hemodynamic and respiratory monitoring, and drug intervention when required. Twenty-four hour survival and neurologic deficit were used as critical measures of outcome. Ten of 30 animals survived 24 hours with a mean neurologic deficit score of 5% (normal = 0, brain dead = 100). There was no difference in initial resuscitation success, 24 hour survival or neurologic deficit of the survivors among the three manual cardiopulmonary resuscitation methods. Aortic diastolic and calculated coronary perfusion pressures were similar for all three methods. Well performed standard manual cardiopulmonary resuscitation is as effective as these modified versions (high impulse compression and interposed abdominal compression) when compared in the same animal model.

Animals↗
PubMed1985

Expired PCO2 as an index of coronary perfusion pressure.

Presently, there is no reliable noninvasive method of assessing the adequacy of cardiopulmonary resuscitation (CPR). Studies of animals have shown that during prolonged arrest the coronary perfusion pressure (CPP) is correlated with successful resuscitation. During previous studies it appeared that expired PCO2 correlated with CPP. To investigate this relationship, eight mongrel dogs (mean weight, 22.7 +/- 5.8 kg) were anesthetized with pentobarbital. Catheters were placed in the thoracic aorta and right atrium of each dog. Each animal was electrically fibrillated, and CPR was started using mechanical resuscitator. The PCO2 was determined at end expiration using a Hewlett Packard 47210A Capnometer with the electrode attached to the endotracheal tube. After 10, 15, 20, or 25 minutes of ventricular fibrillation and closed-chest massage, a thoracotomy was performed, and internal massage was begun. Coronary perfusion pressure was calculated at least each minute and correlated with the PCO2 values. A correlation coefficient of 0.78 was calculated based on 368 data points for eight dogs (P less than 0.01). The results of this study indicate that expired PCO2 is positively correlated with CPP in the canine model of CPR. Inasmuch as CPP correlates with survival in prolonged CPR, the noninvasive measurement of PCO2 may be a useful method of assessing the adequacy of CPR.

Animals↗
PubMed1985

Expired PCO2 as a prognostic indicator of successful resuscitation from cardiac arrest.

We performed a study to determine if the measurement of expired PCO2 during CPR for cardiac arrest could be used as a prognostic indicator of successful resuscitation. Twelve mongrel dogs were fibrillated electrically, and external chest massage and assisted ventilation were applied for 15 minutes. Expired PCO2 and aortic and right atrial pressures were monitored each minute of arrest. Coronary perfusion pressure (CPP) was calculated by subtracting the right atrial from the aortic diastolic pressure. Half the dogs received high-force chest compression (80 lb) and half received low-force chest compression (40 lb). The six dogs that received high-force compression were resuscitated successfully. The expired PCO2 was significantly higher in the successfully resuscitated dogs (expired PCO2 = 9.6 +/- 3.2 mm Hg) when compared to those dogs that died (expired PCO2 = 3.2 +/- 1.1 mm Hg, P less than .01). Expired PCO2 was highly correlated (r = 0.91, P less than .01) with the CPPs. The measurement of expired PCO2 during attempted CPR may be useful as a noninvasive indicator of CPP and adequate technique. Further studies on the use of this technique as an assessment criterion are warranted.

Animals↗
PubMed1985

Importance of the duration of inadequate coronary perfusion pressure on resuscitation from cardiac arrest.

The effect of the duration of inadequate coronary perfusion pressure on resuscitation from cardiac arrest was examined in 32 mongrel dogs with a mean weight of 22 +/- 5 kg. In all dogs, the heart was electrically fibrillated and closed chest compression with assisted ventilation was performed for 15 minutes. At this time, all dogs had an inadequate coronary perfusion pressure (mean 7 +/- 9 mm Hg) and were randomized to a control group (group 1) with continued closed chest compression or to one of the three groups with open chest cardiac massage. These three groups differed only in the duration of continued closed chest compression before initiation of open chest massage (15, 20 and 25 minutes, respectively, in groups 2, 3 and 4). The control group (group 1) had no significant increase in coronary perfusion pressure, and only one of the eight dogs could be resuscitated. The three groups with open chest cardiac massage had a significant increase in coronary perfusion pressure (from 5 +/- 9 to 51 +/- 26 mm Hg, p less than 0.05), but the rate of successful resuscitation depended on the duration of inadequate coronary perfusion pressure before cardiac open chest massage. In group 2, six of eight dogs were resuscitated (p less than 0.05 compared with the control group); in group 3, three of eight dogs were resuscitated and in group 4 none of the eight dogs was resuscitated. The resuscitation rate was significantly (p less than 0.05) greater in group 2 than in group 4. These findings indicate that techniques that improve coronary perfusion pressure during cardiopulmonary resuscitation must be applied before extensive myocardial cellular dysfunction occurs if the probability of successful resuscitation is to be improved.

Animals↗
PubMed1985

Manual versus mechanical cardiopulmonary resuscitation in an experimental canine model.

Manual and mechanical chest compressions during CPR were compared in the canine model. Endpoints were hemodynamics produced during CPR, resuscitation success at 30 min, 24-h survival, neurologic function of survivors, and CPR-produced trauma. Ten animals in each group underwent 20 min of ventricular fibrillation, during which CPR was performed for 17 min. Hemodynamics produced with manual and mechanical chest compressions were similar. Seven of ten animals in each group were resuscitated. Five animals from the manual group and four animals from the mechanical group survived for 24 h. Neurologic function of survivors was excellent and similar in each group. There was no significant difference in trauma between the two types of chest compression. The similar results for manual and mechanical chest compression in this canine model suggest that different experimental CPR studies can be compared regardless or whether manual or mechanical chest compressions were performed.

Animals↗
PubMed1984

An expert consultation system for frontline health workers in primary eye care.

In developing countries, blindness is a major health problem whose control depends on the application of simple measures by frontline workers because, in many of these countries, specialist medical care is not readily available. To assist primary health workers in the management of common and potentially blinding eye disorders, we have developed a prototype computer program for a hand-held computer that incorporates a set of guidelines for diagnosis and treatment. This eye treatment program will help evaluate the potential of such devices for improving health care delivery in developing countries. This approach is now feasible because of recent advances in expert system and portable computer technology.

Blindness↗
PubMed1984

Improved resuscitation from cardiac arrest with open-chest massage.

A study was done to assess the effect of open-chest massage on resuscitation from cardiac arrest. Ten mongrel dogs weighing 20.3 +/- 3.2 kg were fibrillated electrically. Cardiopulmonary resuscitation (CPR) was initiated and continued for 15 minutes. Half the dogs with coronary perfusion pressures less than 30 mm Hg underwent thoracotomy and internal cardiac massage for three minutes. Closed-chest massage was continued with the other dogs. All dogs were defibrillated at 19 minutes, and resuscitation was determined at 20 minutes after defibrillation. None of the dogs in the closed-chest massage group was resuscitated successfully. Four of the five dogs that underwent open cardiac massage were resuscitated. Significant differences in aortic pressures and coronary perfusion pressures were noted for the first two minutes of open-chest massage (P less than .05). The results of this study indicate that resuscitation may be improved using open-chest massage when closed-chest massage fails to produce an adequate coronary perfusion pressure.

Animals↗
PubMed1984

Diabetes insipidus: occurrence after minor head trauma.

Post-traumatic diabetes insipidus is a rare entity, usually associated with severe head trauma, often with skull fracture and cranial nerve dysfunction. A 24-year-old male presented to a medical clinic 2 weeks after a minor head injury with presenting symptoms of polyuria with nocturia and intense polydipsia. A diagnosis of post-traumatic diabetes insipidus was made. Although other causes of polyuria syndromes must be ruled out, plotting urine versus plasma osmolalities can provide rapid preliminary diagnostic help when considering diabetes insipidus. First-line treatment should include a trial of chlorpropamide and hydrochlorothiazide. Caution should be exercised in not overlooking associated anterior pituitary damage, which may develop several years post-trauma.

Adult↗
PubMed1983

Continuous intracoronary nitroglycerin infusion for spasm after angioplasty.

A patient with reversible coronary artery spasm superimposed on fixed atherosclerotic coronary disease was treated with percutaneous transluminal angioplasty. The procedure successfully dilated the atherosclerotic lesion. However, 20 minutes later, the patient developed coronary artery spasm at the angioplasty site. Sublingual nitroglycerin, sublingual nifedipine, intravenous nitroglycerin, and repeated boluses of intracoronary nitroglycerin alleviated episodes of spasm, but failed to prevent recurrence. The patient was successfully treated with a continuous intracoronary infusion of nitroglycerin. Patients with coronary artery spasm in addition to fixed obstructive coronary disease may be at higher risk for spasm after percutaneous transluminal angioplasty. Continuous intracoronary infusion of nitroglycerin may be an effective therapy for recurrent coronary artery spasm occurring in the catheterization laboratory.

Aged↗
PubMed1983

Mexiletine in refractory ventricular arrhythmias.

The antiarrhythmic efficacy of mexiletine was evaluated in 28 subjects with recurrent ventricular tachycardia or fibrillation (22 subjects) or with symptomatic complex ventricular ectopy (six subjects). In all, either the arrhythmia was refractory to other drugs, or such therapy was not tolerated. Response to mexiletine was assessed by continuous ECGs, and in five cases by programmed electrical stimulation. Mexiletine abolished the arrhythmia in 12 cases, but was not tolerated long-term in four. Mexiletine was ineffective in 10 subjects. Seven subjects had significant adverse reactions during short-term dosing; in six, mexiletine was discontinued because of adverse effects after the first few doses so efficacy was not evaluated. The most common adverse effects were nausea, tremor, and generalized malaise. We conclude that mexiletine is an effective antiarrhythmic in some patients with life-threatening ventricular arrhythmias refractory to conventional drugs. Adverse effects significantly limit its use.

Aged↗
PubMedDate not supplied

Evaluation of cardiomyoplasty and skeletal muscle ventricle procedures in a clinically realistic animal model.

Cardiomyoplasty and skeletal muscle ventricle procedures have shown increasing promise in the treatment of cardiomyopathy with associated chronic congestive heart failure. More than 100 patients have now received such procedures worldwide. The clinical results to date have been mostly anecdotal with subjective improvement but without firm objective data to collaborate the subjective impression. A clinically realistic animal model would have tremendous advantages to help elucidate the mechanisms by which cardiomyoplasty or skeletal muscle ventricles improve the sense of well-being of patients who have congestive heart failure. Several possible animal models exist, including pharmacologically induced congestive heart failure models and postischemic injury cardiomyopathy models. The most intriguing, however, is a spontaneously occurring cardiomyopathy in large dogs. This idiopathic cardiomyopathy that appears mainly in large-breed dogs (Great Danes, Dobermans, and Saint Bernards) has a rapidly progressive course; it has a 6-month mortality rate of 75% and a 12-month mortality rate of 95% to 100%. The most efficacious use of such an experimental model would include the evaluation of cardiomyoplasty and skeletal muscle ventricle procedures in a multidimensional fashion. Experimental endpoints should include mortality, exercise tolerance, systolic and diastolic ventricular function, and arrhythmia occurrence. Sophisticated techniques now exist for the evaluation of systolic and diastolic ventricular function. Such evaluation may well provide additional insight into how such experimental procedures benefit those with congestive heart failure.

Animals↗