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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thyroid storm is a rapid decompensation of severe hyperthyroidism which can best be described by the three criteria of hyperthermia, tachycardia and altered mental state with severe agitation. There has to be a precipitating factor such as infection, iodine contamination, surgery or even I-131 treatment. Severe hyperthyroidism not fulfilling the criteria of thyroid storm can also be an indication for emergency treatment, particularly in the elderly with heart disease. Suppressed serum TSH and elevated free T4 levels are essential to confirm the diagnosis. When rapidly available, radioiodine uptake of the thyroid can be useful. Therapy aims at rapidly reducing the active circulating hormone pool, hypermetabolic state, tachycardia, and finally hormone synthesis. Thyroid secretion can be blocked by ioipanoic acid or ipodate while hypermetabolic state can be reduced with beta-blockers or calcium channel-blockers. Treatment of hyperthyroidism in patients with iodine contamination is a real therapeutic challenge. Myxoedema coma, a complication of severe hypothyroidism, is defined by hypothermia (rectal temperature less than 36 degrees C), bradycardia, slow mentation, precipitating factor such as infection or drug overdose, and increased serum creatine phosphokinase levels. Diagnosis of severe hypothyroidism should be confirmed by serum measurements of TSH and free T4. Treatment consists of general supporting measures including rewarming, correction of serum electrolyte disturbances, and adequate alimentation. Thyroid hormone treatment should initially be aggressive using either 300-400 micrograms of T4 or 20-40 micrograms of T3 intravenously. Cortisone therapy may be added. Patients should be under close monitoring as arrhythmias and myocardial infarction are frequent complications of myxoedema coma and/or its treatment with thyroid hormones.
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PMID:Thyroid emergencies. 173 98

Diaphragm paralysis has been reported radiologically after cardiac surgery with an incidence ranging from 30% to 75% of patients. We studied 100 consecutive patients undergoing open heart operations, half of whom received ice/slush topical hypothermia (group 1) and half of whom did not (group 2). Chest radiology and diaphragm screening were performed at 1 week, 1 month, and every 6 months thereafter in all patients with an elevated diaphragm. Phrenic nerve conduction time was measured in all patients in whom there was radiological evidence of diaphragm paralysis 1 week postoperatively. The two groups were similar in terms of age and sex. Aortic cross-clamp time was less in group 1 (61.5 +/- 15.6 minutes) compared with group II (74.4 +/- 20.8 minutes), although this difference was not significant. Significant differences, however, were found for radiological evidence of partial left lower lobe collapse (82% in group 1 versus 32% in group 2; p less than 0.01) and for radiological evidence of diaphragm paralysis (32% in group 1 versus 2% in group 2; p less than 0.001) within the first postoperative week. Unilateral diaphragm paralysis developed in 16 group 1 patients (15 left sided, 1 right sided) compared with only 1 patient in group 2. In these 16 group 1 patients, diaphragm paralysis was still present in 12 (75%) at 1 month and in 5 (31.3%) at 1 year postoperatively. There were no significant differences between the two groups in terms of postoperative arrhythmias, myocardial infarction, or mortality. Phrenic nerve conduction time was found to be a sensitive indicator of phrenic nerve cold injury and recovery.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Diaphragm paralysis following cardiac surgery: role of phrenic nerve cold injury. 192 16

This study summarizes our experience with 90 patients (68 male and 22 female, mean age 57.2 years). From Jan. 1980 to Feb. 1990, 51.1% underwent surgery for dissection of the aorta; the rest for acute aortic ruptures, false and true aneurysms. Procedures with reconstruction of the aortic arch were performed in cases of deep hypothermia and circulatory arrest (no fatal courses). The overall death rate was 18.8% (emergency 29.5%, elective 8.7%). Acute dissections Type I had the highest perioperative mortality with 29.4%. The leading causes of early death were myocardial infarction (23.5%) and cerebral injury (23.5%). Therefore coronary angiograms should be performed preoperatively in older patients. A major problem in our experience is the long-term followup examination which should remain the surgeon's responsibility.
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PMID:[Aortic aneurysm and aortic injury--surgical treatment and follow-up]. 198

From August 1984 through November 1988, 10 of 2,658 patients undergoing coronary artery bypass grafting had ascending aortic disease that was not amenable to proximal anastomoses for coronary bypass grafting. This was due to a calcified aorta in 6 and acute aortic dissection in 4. There were 5 male and 5 female patients with a mean age of 71 years. Cannulation site was the femoral artery in 5, ascending aorta in 3, and aortic arch in 2. Profound hypothermia and ventricular fibrillation, with no cross-clamp or cardioplegia, was used in 9 patients, and circulatory arrest in 1. In 8 patients a single internal mammary artery was used as the total inflow with a saphenous vein graft brought off the internal mammary artery to one or more distal left-sided coronary vessels. Bilateral internal mammary arteries were used in 2 other patients. Operative mortality was zero. There was one perioperative myocardial infarction and one transient stroke without sequelae. All patients have done well from 1 to 6 years postoperatively. These data support the use of internal mammary arteries as single or bilateral proximal conduits for other venoarterial bypass grafts when the aorta is extensively diseased either by calcification or dissection.
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PMID:Coronary bypass grafting with totally calcified or acutely dissected ascending aorta. 198 45

This report presents the results in our first clinical series of patients receiving continuous warm blood cardioplegia through the coronary sinus. Warm oxygenated blood cardioplegia has certain theoretical advantages, such as continuously supplying oxygen and substrates to the arrested heart while avoiding the side effects of hypothermia. Retrograde infusion of cardioplegia also offers certain advantages (eg, in valve operations and in patients with severe coronary artery disease) that are complementary to warm blood cardioplegia. Retrograde warm blood cardioplegia was used in 113 consecutive patients (85 men and 28 women with a mean age of 61 years) undergoing various procedures. Three percent of the patients died, 7% needed transient intraaortic balloon pump support, 6% had evidence of perioperative myocardial infarction, and 96% had spontaneous return of rhythm. There were no coronary sinus injuries. This new technique of retrograde continuous warm blood cardioplegia is a simple, safe, and reliable method of myocardial protection that may change the way we currently protect the heart intraoperatively.
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PMID:Retrograde continuous warm blood cardioplegia: a new concept in myocardial protection. 198 29

Hypothermia is widely acknowledged to be the fundamental component of myocardial protection during cardiac operations. Although it prolongs the period of ischemic arrest by reducing oxygen demands, hypothermia is associated with a number of major disadvantages, including its detrimental effects on enzymatic function, energy generation, and cellular integrity. We hypothesized that the ideal protected state of the heart would be electromechanically arrested and perfused with blood, that is, aerobic arrest. Under these conditions the fundamental need for hypothermia becomes questionable. We have developed a novel approach to myocardial protection during cardiac operations based on these concepts, in which the chemically arrested heart is perfused continuously with blood and maintained at 37 degrees C. In 121 consecutive coronary bypass procedures we have compared this approach with a historical cohort of 133 consecutive patients treated with hypothermic cardioplegia. Perioperative myocardial infarction was significantly less prevalent (1.7% versus 6.8%; p less than 0.05) in the warm cardioplegic group, as was the use of the intraaortic balloon pump (0.9% versus 9.0%; p less than 0.005) and the prevalence of low output syndrome (13.5% versus 3.3%; p less than 0.005). Cardiac output immediately after bypass was significantly higher than before bypass (3.1 +/- 0.9 versus 4.9 +/- 1.0 L/min; p less than 0.001) only in the warm cardioplegia group. Furthermore, the heartbeat in 99.2% of patients treated with continuous warm cardioplegia converted to normal sinus rhythm spontaneously after removal of the aortic crossclamp compared with only 10.5% of the hypothermic group. The time from removal of the aortic crossclamp to discontinuation of cardiopulmonary bypass (i.e., reperfusion time) was significantly shorter in the warm cardioplegia group (11 +/- 4.3 versus 27 +/- 5.6 minutes; p less than 0.001). Our results suggest that continuous normothermic blood cardioplegia is safe and effective. Conceptually, this represents a new approach to the problem of maintaining excellent myocardial preservation during cardiac operations.
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PMID:Warm heart surgery. 199 37

The role of perfusion pressure and flow during cardiopulmonary bypass with moderate hypothermia and hemodilution in the development of new postoperative renal or clinically apparent cerebral dysfunction was examined in 504 adults. Cardiopulmonary bypass flow was targeted at greater than 40 mL.kg-1.min-1 and pressure at greater than 50 mm Hg. Flows and pressures less than target occurred in 21.6% and 97.1% of patients, respectively. Fifteen patients (3.0%) suffered new renal and 13 (2.6%) new central nervous system dysfunction. Low pressure or flow during cardiopulmonary bypass, expressed in absolute values or in intensity-duration units, were not predictors of either adverse outcome. Multivariate analysis identified use of postoperative intraaortic balloon counterpulsation (p less than 10(-6], excessive blood loss in the ICU (p less than 10(-4], need for vasopressors before cardiopulmonary bypass (p less than 10(-4], postoperative myocardial infarction (p less than 10(-3], emergency reoperation (p less than 0.002), excessive postoperative transfusion (p less than 0.02), and chronic renal disease (p less than 0.03) as independent predictors of postoperative renal dysfunction. Independent predictors of postoperative central nervous system dysfunction were cardiopulmonary resuscitation in the intensive care unit (p less than 10(-6], intracardiac thrombus or valve calcification (p less than 0.02), and chronic renal disease (p less than 0.03). Age greater than 65 years (40.7% of patients) did not predict either outcome. We conclude that failure of the native circulation during periods other than cardiopulmonary bypass rather than the flows and pressures considered here is the major cause of renal and clinically apparent central nervous system dysfunction after cardiac operations.
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PMID:Role of perfusion pressure and flow in major organ dysfunction after cardiopulmonary bypass. 224 82

Systemic hypothermia at 25 degrees-28 degrees C without chemical cardioplegia was used in 908 patients undergoing coronary artery bypass grafting. Local coronary artery flow was interrupted only during grafting of a distal anastomosis. Systemic perfusion pressure was maintained at 80-100 mmHg, hematocrit at 20%-25%, and pCO2 and pH were monitored during hypothermia according to the alpha-stat principle, while the left ventricle was vented routinely. Proximal anastomoses were performed just before extracorporeal circulation was started by only partially occluding the ascending aorta. Preoperatively 61.9% of the patients had had a myocardial infarction, and 44% had unstable angina. In 14% a severe lesion of the main stem of the left coronary artery was present. Left ventricular function was moderately depressed in 25% and severely depressed in 8% of the patients. Forty-eight patients (5.3%) were aged 70 years or older. The mean number of grafts placed per patient was 3.3. Perioperative myocardial infarction occurred in 3%. Death due to left ventricular failure occurred in 0.4%. No left ventricular assist devices were needed; an intra-aortic balloon pump was used in 1%; positive inotropic support was required in 3.8% of the patients. These results indicate that systemic hypothermia alone provides safe myocardial protection and in certain cases may be the method of choice, particularly if aortic cross clamping or administration of cardioplegic solution is contraindicated. In addition, this method provides rapid revascularization of a severely ischemic zone, as present after unsuccessful PTCA procedures.
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PMID:Myocardial protection by simple systemic hypothermia without aortic occlusion. 226 41

By uni- and multivariate analysis, predictors of surgical mortality and postoperative angina were identified retrospectively in 189 patients having had coronary arterial bypass surgery over the period 1978-1984. After modification of these risk factors, surgical outcome was followed up in another 178 patients undergoing operation from 1985 to 1987. The surgical mortality of 7% in the first series was closely associated with postoperative signs of acute myocardial injury. All deaths occurred in patients having at least 3 out of 5 pre- and peroperative risk factors: triple vessel/left main coronary arterial disease, incomplete revascularization, no propranolol treatment, Bretschneider cardioplegia other than "HTP"-solution with blood preperfusion and perioperative vasopressor support. The procedures of cardiac protection were modified. St Thomas multidose potassium cardioplegia and general hypothermia were introduced, perioperative propranolol treatment increased and bypass time decreased. Improved cardiac protection with this regime was seen in the patients operated in 1985-1987 when compared with the first series with regard to perioperative vasopressor support (8 vs 33%, P less than 0.001), spontaneous operative defibrillation (72 vs 52%, P less than 0.001), postoperative arrhythmias (20 vs 43%, P less than 0.001), peak levels of serum enzymes (P less than 0.001), myocardial infarction (7 vs 19%, P less than 0.001) and hospital mortality (2 vs 7%, P less than 0.05). The incidence of freedom from symptoms at 3 months was also increased in the patients undergoing operation from 1985 to 1987 (72 vs 61%, P less than 0.05). Even small centers can improve their surgical outcome by carefully analysing their own results and modifying the identified risk factors.
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PMID:Improved outcome of coronary arterial bypass surgery in a small center after identification and modification of peroperative risk factors. 229 14

The left coronary artery was ligated and myocardial infarction developed in 28 rats. Three weeks later, the hearts were excised and mounted in an apparatus for perfusion of non-working isolated hearts (Langendorff). Hypothermic (15 degrees C), ischemic cardioplegia was induced for either 2 or 3 1/2 h followed by reperfusion for 45 min. Half of the hearts were reperfused with an initially gradual rise in temperature and pressure of the perfusion fluid, whereas the other half was reperfused directly with the perfusate at 37 degrees C and 100 cm H2O pressure. The hearts were examined by transmission electron microscopy and randomized for stereological analysis based on point counting on electron micrographs. Cardioplegia of 2 h duration was tolerated better than cardioplegia for 3 1/2 h (interstitial edema; P = 0.03, fraction of altered mitochondria; P = 0.001). Particularly in the hearts undergoing the longest cardioplegia, myocardial injury was less severe following a gentle reperfusion as compared with those exposed to the clinically common abrupt technique (fraction of mitochondria in the myocyte; P = 0.03, fraction of altered mitochondria; P = 0.008). In the interstitium, the luminal area of capillaries was significantly increased and the endothelial swelling less pronounced in the groups undergoing the gentle reperfusion technique, (luminal/endothelial fraction; P = 0.01). The study shows that previously infarcted hearts are susceptible to ischemic damage even after 2 h of regular hypothermic, ischemic cardioplegia and that a gentle reperfusion technique significantly ameliorates reperfusion injury.
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PMID:Amelioration of reperfusion injury following hypothermic, ischemic cardioplegia in isolated, infarcted rat hearts. 230 80


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