General Body Hypothermia Research Articles

Therapeutic hypothermia in acute myocardial infarction

The review provides basic information on the effect of therapeutic hypothermia on myocardial ischemia, as well as analyzes experimental and clinical studies on therapeutic hypothermia in myocardial infarction. The results of comparison of general body hypothermia and local myocardial hypothermia are discussed. The ways of further studies of this technology in myocardial infarction are outlined.

In this issue

It is commonly thought that it is advantageous to develop general body hypothermia in near-drowning cases. The study by Suomenin and colleagues from Finland (page 111) challenges this view and this topic is covered in a separate editorial by Dr. Golden (page 107).

The Birth of Open-Heart Surgery: Then the Golden Years

The development of open-heart surgery has been reviewed beginning with general body hypothermia and inflow stasis, then continuing with extracorporeal circulation by controlled cross-circulation. The successes with the latter technique stimulated rapid development of the simple disposable highly effective bubble oxygenator for extracorporeal circulation to permit correction of virtually all forms of congenital and acquired heart disease. For the few conditions not amenable to corrective procedures, heart replacement became a practical reality. The creation of chronic heart block in the early operations had a very deleterious effect upon survival until highly effective electrical pacing was developed.

Further experience with general body hypothermia in the treatment of massive gastrointestinal hemorrhage

Moderate general body hypothermia has been used in twenty-three patients to control gastrointestinal bleeding and in two other patients to control intraperitoneal bleeding. At least temporary cessation of bleeding occurred in eighteen patients. Experimental and clinical observations are described which show a decrease in gastric pepsin during hypothermia as well as a decrease in cardiac output without evidence of anaerobic metabolism. General body hypothermia may be useful in selected patients with massive gastrointestinal bleeding.

Multiple valve replacement.

ESTABLISHMENT of safe, prolonged extracorporeal circulation and the advent of suitable prosthetic valves have allowed surgeons to operate upon patients with multiple valvular deformities. Due to the increased duration of the operative procedure and additional trauma, the mortality of multiple valve insertion would appear to be incremental with each valve replaced. In review of our own cases, however, this has not been found. The late mortality indicates a need for conscientious involvement by physicians in the long-term care of such patients. Material Preoperative evaluation of all patients with multivalvular disease consists of chest x-ray films, electrocardiograms, routine laboratory studies, and cardiac catheterization. Occasionally the clinical signs of valve malfunction are sufficiently overt that cardiac catheterization is not deemed essential. Angiography is rarely used as an aid in establishment of the diagnosis. All patients are operated upon with the use of mild general body hypothermia (32 to 34 C) and rotating

Canine "cadaver" kidneys. Their procurement and application to clinical homotransplantation.

To retrieve cadaver kidneys for human homotransplantation, organ viability must be maintained in vivo during the preterminal period when renal perfusion is low, and in vitro during the period while the recipient is being prepared. In the laboratory, experiments were designed to simulate the clinical situation in which canine cadaver kidneys are used. It was found that general profound hypothermia before death inhibits to a significant degree the untoward effects of renal ischemia by virtue of its suppressive action on metabolic activity. General body hypothermia to 28 C (82.4 F) applied three hours before death permits removal of viable, transplantable kidneys up to two hours postmortem. No treatment at all requires immediate removal of the kidney to retain its viability. This study suggests that for successful use of cadaver kidneys in human homotransplantation, both in vivo and in vitro renal protection from ischemia are of paramount importance for ultimate success.

Canine "Cadaver" Kidneys

To retrieve cadaver kidneys for human homotransplantation, organ viability must be maintained in vivo during the preterminal period when renal perfusion is low, and in vitro during the period while the recipient is being prepared. In the laboratory, experiments were designed to simulate the clinical situation in which canine cadaver kidneys are used. It was found that general profound hypothermia before death inhibits to a significant degree the untoward effects of renal ischemia by virtue of its suppressive action on metabolic activity. General body hypothermia to 28 C (82.4 F) applied three hours before death permits removal of viable, transplantable kidneys up to two hours postmortem. No treatment at all requires immediate removal of the kidney to retain its viability. This study suggests that for successful use of cadaver kidneys in human homotransplantation, both in vivo and in vitro renal protection from ischemia are of paramount importance for ultimate success.

82. Experimental and Clinical Uses of an Ambulance Equiped with Surface Cooling General Body Hypothermia Machine

82. Experimental and Clinical Uses of an Ambulance Equiped with Surface Cooling General Body Hypothermia Machine

EFFECTS OF HYPOTHERMIA ON MYOCARDIAL CONTRACTILE FORCE.

It is well known that general body hypothermia results in a decrease in heart rate and an associated increase in ventricular contractile force. Previous studies of this temperature effect on myocardial activity have been restricted to isolated heart preparations or intact animals in which the entire body was cooled. 1-4 The present studies were designed to investigate the site of action of hypothermia on myocardial contraction in intact animals utilizing separate cardiopulmonary and systemic perfusion systems. Materials and Methods Adult fasting mongrel dogs weighing 16 to 22 kg were used. After induction of anesthesia with intravenous thiopental (20 mg/kg) a cuffed endotracheal tube was inserted and ventilation was maintained by a positive pressure respirator supplying room air. A bilateral anterior thoracotomy was performed through the fourth intercostal spaces and the sternum transected. Heparin was administered intravenously. Cardiopulmonary bypass was then effected by draining venous blood from the venae cavae to

Protective effects of hypothermia in exploration of space.

Manned probes into space may present a number of difficult and as yet unsolved biomedical problems. This review outlines a significant number of protective effects of general hypothermia. Hypothermia reduces the rate of cellular metabolism. Added advantages of protection from shock in dysbarism, bacteremia, trauma, and excessive g forces are cited. Protection against radiation during hypothermia appears significant. The authors point out that the advantages in terms of reduction in weight and bulk are enormous. However, a state of artificial hibernation appears to be preferable to deeper degrees of cooling, because general body hypothermia is a stressful condition.

Calcific aortic stenosis

Aortic valvuloplasty for calcific aortic stenosis requires the removal of large calcified plaques from the leaflets, particularly at the hinge areas at the bases of the leaflets, and opening the commissures to the annulus. By this technic the leaflets are made flexible, and an adequate and competent valve can be obtained in the large majority of instances. Extracorporeal circulation combined with general body hypothermia and selective hypothermia to the heart is an ideal method for this procedure, and it offers maximum protection to the patient. Additional protection for the heart can be obtained with intermittent coronary perfusion We have used this technic of aortic valvuloplasty in a consecutive series of sixteen patients with calcific aortic stenosis. Three patients died, a mortality rate of 19 per cent; ten patients have had an excellent result, two a good result and one a fair result.

Aortic valve replacement with a gaged ball valve

1. 1. Valve types and various materials are discussed. 2. 2. Skepticism is expressed regarding the durability of nonwettable cusps that must undergo double or triple flexion. 3. 3. Construction of ball valves in general is reviewed with specifications of this human aortic prosthesis. 4. 4. Fatigue, biologic and hydraulic testing devices are presented. 5. 5. Clinical results with two series of patients 1 year apart are reviewed in relation to technical problems and their solution. The problem of cardiac resuscitation has been greatly reduced by using moderate general body hypothermia, and profound local hypothermia to achieve cardioplegia. 6. 6. Late follow-up of patients 6 to 19 months after prosthetic replacement of the aortic valve is reported. The caged ball valve has been hemodynamically sound. There has been no evidence of damage to formed blood elements and no peripheral embolization. 7. 7. The ten cardinal features of prosthetic valves are defined.

The present status of pump-oxygenators and some problems related to their use

The present status of pump-oxygenators and some problems related to their use

Canine renal autografts. Studies of reversible histopathologic changes following prolonged extracorporeal refrigeration.

Recently we have had an opportunity to observe histologic changes in dog kidneys during renal autoreplantation studies. While attempting to increase the period of ischemia tolerated by the dog kidney, biopsies have been taken of kidneys during various stages of extracorporeal hypothermia. The present study was designed to provide a serial histologic record of the changes found in a hypothermic kidney which resumed normal, life-sustaining, function after a prolonged interval outside the donor animal's body. By restricting our investigation to autoreplantations (kidney regrafted into original site in donor with anastomoses to original vascular supply, and end-to-end ureteral anastomosis) the well-recognized pathologic changes of the homograft rejection phenomenon were avoided. Changes observed in renal tubular cells could be more accurately attributed to hypothermia, ischemia, thrombosis, or infection. The introduction of general body hypothermia as an adjunct to cardiac surgery has again directed attention to the possible benefits of local cooling in

RESECTION OF THE THORACIC AORTA WITH REPLACEMENT BY HOMOGRAFT FOR ANEURYSMS AND CONSTRICTIVE LESIONS

For fusiform aneurysms and constrictive lesions of the descending thoracic aorta, resection of an extensive segment of aorta may be necessary making end-to-end anastomosis impossible. In such cases restoration of aortic circulation may be achieved by insertion of vascular homografts. This method of therapy was employed in twelve thoracic aortic resections, seven of which were done for aneurysm and five for constrictive lesions. The degree of ischemic damage to the spinal cord occurring during periods of temporary aortic occlusion is influenced by a number of factors, including the duration of occlusion, extent and location of the lesion, and extent to which collateral circulation exists. In constrictive lesions the collateral circulation is usually well developed, and temporary aortic occlusion may be tolerated for indefinite periods. In aneurysms, however, where collateral circulation is poorly developed, successful performance of aortic resection depends upon prevention of ischemic damage to the spinal cord during temporary aortic cross-clamping. Two cases of aneurysm are reported in which general body hypothermia was employed, and another in which local spinal cooling was used to prevent postoperative paraplegia. Other means of reducing this hazard are concerned with the technical procedure itself. In constrictive lesions, where there is no haste in restoration of aortic flow, emphasis is placed upon precise reconstruction of all major vascular channels by homograft. One case of acquired coarctation of the aorta is reported in which constrictions occurred in the lower thoracic aorta and in the proximal abdominal aorta. Good results were obtained after two homografts were inserted to replace the diseased segment of aorta. Addendum .—Since the preparation of this manuscript, 9 additional cases have been performed, 5 of which were done for aneurysms and 4 for constrictive lesions. All of these patients recovered, making a total of 21 cases with 3 deaths (14.3 per cent). Of particular interest is the fact that two of the additional patients had aneurysms involving the distal part of the aortic arch similar to that described in Case 6. In both of these patients the resection and graft replacement was done under general hypothermia as described in Case 6. The proximal occluding clamp was applied just distal to the left common carotid artery in each for periods of 58 and 50 minutes, respectively. Both have completely recovered with no evidence of ischemic damage to the spinal cord or other viscera.