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

The importance of temperature in the development of necrosis after myocardial ischemia in the beating heart is becoming apparent. Recent studies have shown that the proportion of the ischemic risk zone that becomes necrotic is directly correlated with temperature. This fact suggests the potential therapeutic benefits of reducing myocardial temperature after coronary artery occlusion. We have shown in a number of experimental protocols in the rabbit model of myocardial infarction that topical regional hypothermia reduces infarct size even when instituted after coronary artery occlusion. The reduction in myocardial temperature required to obtain this benefit is modest ( 30 degrees C to 34 degrees C). Topical regional hypothermia allows targeted cooling of a zone of the heart. Myocardial cooling can also be achieved by perfusing the pericardial sac with a chilled fluid by using a closed-circuit catheter system that does not cause cardiac tamponade. This technique also protects myocardium during ischemia. Myocardial hypothermia might be a useful technique to limit ischemic damage during infarction or as adjunctive therapy during minimally invasive cardiac surgery.
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PMID:Myocardial hypothermia: a potential therapeutic technique for acute regional myocardial ischemia. 1021 May 4

We evaluated the risk of perioperative cardiac ischemia associated with mild hypothermia as adjunct management for neurosurgical procedures. Forty-seven elective neurosurgical patients were randomly assigned to either hypothermic group (H, n = 24) or normothermic one (N, n = 23). Patients in group H were cooled to and maintained at 34.5 degrees C (tympanic membrane temperature) and rewarmed after main neurosurgical manipulation, while those in group N were kept in normothermic state. Cardiac ischemia was diagnosed with Holter electrocardiogram monitored for 24 hours after admission to the operating room. No differences were observed in demographic data including age, gender, weight, height, rate of having cardiac disease, anesthesia methods, and contents of surgery. Temperature was significantly lower in group H than N both at the lowest point (34.6 +/- 0.5 vs 35.9 +/- 0.6, mean +/- SD) and at the conclusion of anesthesia (35.9 +/- 0.9 vs 36.5 +/- 0.5). Electrocardiographic ST segmental depression was observed in 3 (group H) and 5 cases (group N), and postoperative shivering occurred in 3 (group H) and 2 cases (group N), respectively. Those incidences were not statistically significant (chi-square test, P was set at 0.05). We concluded that intraoperative mild hypothermia might not increase the risk of perioperative cardiac ischemia in patients for neurosurgical procedures.
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PMID:[The effect of intraoperative mild hypothermia on the development of perioperative cardiac ischemia]. 1051 75

Postoperative hypothermia is common and associated with adverse hemodynamic consequences, including adrenergically mediated systemic vasoconstriction and hypertension. Hypothermia is also a known predictor of dysrhythmias and myocardial ischemia in high-risk patients. We describe a prospective, randomized trial designed to test the hypothesis that forced-air warming (FAW) provides improved hemodynamic variables after coronary artery bypass graft. After institutional review board approval and written informed consent, 149 patients undergoing coronary artery bypass graft were randomized to receive postoperative warming with either FAW (n = 81) or a circulating water mattress (n = 68). Core temperature was measured at the tympanic membrane. A weighted mean skin temperature was calculated. Heart rate, mean arterial blood pressure, central venous pressure, cardiac output, and systemic vascular resistance were monitored for 22 h postoperatively. Mean arterial blood pressure was maintained by protocol between 70 and 80 mm Hg by titration of nitroglycerin and sodium nitroprusside. The two groups had similar demographic characteristics. Tympanic and mean skin temperatures were similar between groups on intensive care unit admission. During postoperative rewarming, tympanic temperature was similar between groups, but mean skin temperature was significantly greater in the FAW group (P < 0.05). Heart rate, mean arterial pressure, central venous pressure, cardiac output, and systemic vascular resistance were similar for the two groups. The percent of patients requiring nitroprusside to achieve the hemodynamic goals was less (P < 0.05) in the FAW group. In conclusion, aggressive cutaneous warming with FAW results in a higher mean skin temperature and a decreased requirement for vasodilator therapy in hypothermic patients after cardiac surgery. This most likely reflects attenuation of the adrenergic response or opening of cutaneous vascular beds as a result of surface warming. IMPLICATIONS Forced-air warming after cardiac surgery decreases the requirement for vasodilator drugs and may be beneficial in maintaining hemodynamic variables within predefined limits.
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PMID:Forced-air warming decreases vasodilator requirement after coronary artery bypass surgery. 1064 8

Recurrent ventricular fibrillation was observed in a 29-year-old Vietnamese man who did not exhibit structural heart disease. The patient's ECG showed prominent J (Osborn) waves and ST segment elevation in the inferior leads that were not associated with hypothermia, serum electrolyte disturbance, or myocardial ischemia. Rate-dependent change in the amplitude of J waves and ST segment elevation also were observed. An implantable cardioverter defibrillator (ICD) was implanted. Adjunctive treatment with amiodarone reduced J wave amplitude, preventing ventricular fibrillation and ICD shocks. Prominent J waves and ST segment elevation in the inferior leads may serve as an important diagnostic sign to detect high-risk individuals with a history of unexplained syncope. ICD implantation plus amiodarone is the treatment of choice.
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PMID:Ventricular fibrillation in a patient with prominent J (Osborn) waves and ST segment elevation in the inferior electrocardiographic leads: a Brugada syndrome variant? 1069 69

During heart surgery, several humoral cascades (coagulation, complement, kallicrein-kinin, cytokines, fibrinolysis) and several cell systems (platelets, neutrophils, endothelial cells, ...) are activated. Numerous contributing factors have been reported: blood contact with foreign surfaces of the extracorporeal circuits, blood-air interface, lung and myocardial ischemia-reperfusion after unclamping, hypothermia, shear stresses, ... A post-perfusion syndrome may develop which include miscellaneous symptoms: coagulation disturbances and bleeding, neurological alterations, inflammatory syndrome, and, in extreme cases, multisystemic organ failure. Even if the present mortality of cardiac surgery is low, several approaches have been proposed to reduce such activations. They are based on changing in the circuit design, or in the composition of the luminal surfaces of the tubing and oxygenator, on improvement of the operative technique, and on modifications of the perfusion technique. Pharmacological agents are also used (anti-inflammatory drugs, corticoids, serine proteases inhibitor (aprotinin, ...). Nevertheless, the development of more biocompatible surfaces seems a promising goal.
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PMID:[Physiopathological disorders related to extracorporeal circulation. Pathogenesis and modes of prevention]. 1093 69

Hypothermic cardiopulmonary bypass alters platelet function and hypothermia is associated with postoperative myocardial ischemia. Thrombogenic surfaces such as extracorporeal circuits, vascular graft materials, and components of atherosclerotic plaque induce activation of platelets. The effects of human hemoglobin (Hb) covalently modified to carry S-nitric oxide (NO) functional groups (SNO-Hb), polyethylene glycol (PEG-Hb), and SNO-PEG-Hb on platelet activation were studied. Platelet activation was assessed by cytometric analysis of GPIIb-IIIa activation and P-selectin expression at hypothermic condition (22 degrees C) after stimulation with Hb derivatives. Platelet adhesion and aggregation were measured in a parallel glass plate chamber coated with unmodified Hb, SNO-Hb, PEG-Hb, SNO-PEG-Hb, and collagen. Platelet binding of antibodies to GPIIb-IIIa and P-selectin was significantly enhanced by hypothermic condition and by unmodified Hb. There was significantly less platelet binding of antibodies to GPIIb-IIIa and P-selectin with SNO-Hb, PEG-Hb, and SNO-PEG-Hb compared with unmodified Hb. There was significantly less platelet attachment, adhesion, and aggregation on the SNO-Hb, PEG-Hb and SNO-PEG-Hb coated surfaces compared with unmodified Hb-coated and -uncoated surfaces. SNO-Hb, PEG-Hb, and SNO-PEG-Hb induced less platelet activation at hypothermic temperature, and induced less platelet adhesion and aggregation on thrombogenic surfaces compared with unmodified Hb. The inhibitory effect may be derived from antiadhesive properties of Hb, antiplatelet actions of NO, and molecular barrier action of PEG.
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PMID:Attenuation of hypothermia-induced platelet activation and platelet adhesion to artificial surfaces in vitro by modification of hemoglobin to carry S-nitric oxide and polyethylene glycol. 1115 32

Correct administration in the early postoperative phase is decisive in the final outcome of surgery and the presence of the Recovery Room (RR) contributes significantly to a reduction in the post-operative risk rate. The objectives of the RR are: removal of the pharmacological effect of general anaesthesia; stabilization of vital parameters (circulation and ventilation); stabilization of body temperature; control of the hydro-electrolytic balance; intensive intervention in the case of an acute complication; prescribing a suitable postoperative analgesia; recovering movement in the case of loco-regional anesthesia. Organization of RR must take into consideration: 1) aspect of environment and location; 2) transport of the patient from the operating room to the RR; 3) definition of the equipment necessary for the RR; 4) definition of the role and qualification of the medical and nursing staff; 5) definition of regulations of assistance and the clinical file; 6) definition of criteria for discharge and transfer; 7) definition of means of adjournment, improvement and comparison with other similar structures. RR is administered by an Anesthetist with clinical, therapeutic and decision-making responsibility for the discharge of patients, while the supervision and assistance patients is entrusted to specialised professional nurses. From a clinical point of view the following data are monitored and recorded: the vital signs (passage of air-ways, cardiac and respiratory frequency, arterial pressure, saturation of O2, EtCO2 (in patient with air-way support), body temperature and the state of consciousness, instrumental monitoring of the patient (at pre-established time intervals), control of the skin, the peripheral circulation, surgical wounds, drainage and catheters. The percentage of incidence of complications in RR varies from 6-7 to 30% depending on various studies, probably in relation to the diversity of criteria in defining the complication. The principal complications which can be found in RR, reported in several studies are: respiratory (obstruction of the air-way, hypoxemia, hypoventilation, inhalation), cardio-circulatory (hypotension, hypertension, arrhythmia, myocardial ischemia), postoperative nausea and vomiting, hypothermia and hyperthermia, delayed re-awakening, disorientation and hyper-excitability, postoperative shivering. As long as the patient can be discharged from the RR the following requisites must be satisfied: return of a state of consciousness, stable cardio-circulatory parameters, absence of respiratory depression, absence of bleeding, absence of nausea and vomiting, good analgesia and recovery of movement in the case of loco-regional anesthesia (on this last point not all authors agree). What has been said until now shows the function, usefulness and importance of RRs which must not replace the Intensive Therapy Units. In fact, they are places where the cure must be concluded, in which the Anesthetist is responsible for the whole process. This cure must begin in the preoperative period, continue in the intraoperative period and it is compulsory to proceed in the immediate postoperative period until such a time that, because of the anesthesia administered, the clinical situation of the patient ceases to be considered a potential medical-surgical urgency-emergency .
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PMID:[Recovery Room. Organization and clinical aspects]. 1160 73

This study was undertaken to determine the factors that influence the final outcome after the operation of aortic arch aneurysm. Sixty-six patients, the median age was 72 years (range 44 to 90), were operated at our hospital during the 16-year period between 1985 and 2001. Preoperative complications included cardiac in 6 and vascular in 21, ruptured in 13, myocardial ischemia in 21 and stroke in 14. The distal hemiarch (11) and total arch replacement with or without ascending aorta and descending aorta (46) and proximal hemiarch with or without valve operations (7) and other procedures were performed mainly using cardio-pulmonary bypass with moderate deep hypothermia and selective cerebral perfusion. The in-hospital mortality were 6 (9%) and 14 (23%) late deaths occurred. One out of 14 was aneurysm related death. The survival rates were 81% at 1 year and 59% at 5 years. The multivariably determined risk factors for early death and postoperative neurological dysfunction were as follows (p < 0.05) cardiac anoxic arrest time, intubation time and gender.
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PMID:[Early and long-term outcome for surgical treatment of aortic arch aneurysm]. 1196 6

Hypothermia is generally defined as a core body temperature less than 35 degrees C (95 degrees F). Hypothermia is one of the most common environmental emergencies encountered by emergency physicians. Although the diagnosis will usually be evident after an initial check of vital signs, the diagnosis can sometimes be missed because of overreliance on normal or near-normal oral or tympanic thermometer readings. The classic and well-known electrocardiographic (ECG) manifestations of hypothermia include the presence of J (Osborn) waves, interval (PR, QRS, QT) prolongation, and atrial and ventricular dysrhythmias. There are also some less known (ECG) findings associated with hypothermia. For example, hypothermia can produce ECG signs that simulate those of acute myocardial ischemia or myocardial infarction. Hypothermia can also blunt the expected ECG findings associated with hyperkalemia. A thorough knowledge of these findings is important for prompt diagnosis and treatment of hypothermia. Six cases are presented that show these important ECG manifestations of hypothermia.
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PMID:Electrocardiographic manifestations of hypothermia. 1209 79

Cardiac surgery often necessitates transfusion of homologous blood. Hemoglobin based oxygen carrying solutions (HBOCs) transport oxygen, suggesting use in cardiopulmonary bypass. HBOC was used in a novel oxygenator double-reservoir circuit that permits acute sequestration of a portion of the autologous blood volume during bypass. Two groups of seven mongrel dogs each were studied in an experimental bypass model using global myocardial ischemia and cardioplegia protection: HBOC group, initial venous return drained to a separate reservoir and hypothermic bypass was conducted with HBOC containing perfusate in a second bypass reservoir; Control group, crystalloid prime in a conventional circuit. Hemodynamics and metabolic and hematologic parameters were measured before and 60 min after aortic clamp removal and reinfusion of sequestered autologous blood. Blood gases, base excess, hematocrit, total hemoglobin, and platelet counts were measured. In the HBOC group, metabolic acidosis did not occur, and ventricular function was preserved. Net conservation of platelets was noted at study conclusion: control 33+/-13 x 10(3) per mm3 versus HBOC 48+/-13 x 10(3), p < 0.05. HBOC based priming in a double venous reservoir system permits bypass at very low hematocrit, with preservation of cardiac function. Net conservation of the platelet mass occurs, a portion of which is not exposed to the deleterious effects of hypothermia and cardiopulmonary bypass.
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PMID:Autologous blood sequestration using a double venous reservoir bypass circuit and polymerized hemoglobin prime. 1214 73


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