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

Pulmonary artery hypertension is defined as persistent elevation of mean pulmonary artery pressure > 25 mm Hg with pulmonary capillary wedge pressure < 15 mm Hg or elevation of exercise mean pulmonary artery pressure > 35 mm Hg. Although mild pulmonary hypertension rarely impacts anesthetic management, severe pulmonary hypertension and exacerbation of moderate hypertension can lead to acute right ventricular failure and cardiogenic shock. Knowledge of anesthetic drug effects on the pulmonary circulation is essential for anesthesiologists. Intraoperative management should include prevention of exacerbating factors such as hypoxemia, hypercarbia, acidosis, hypothermia, hypervolemia, and increased intrathoracic pressure; monitoring and optimizing right ventricular function; and treatment with selective pulmonary vasodilators. Recent advances in pharmacology provide anesthesiologists with a wide variety of options for selective pulmonary vasodilatation. Pulmonary hypertension is a major determinant of perioperative morbidity and mortality in special situations such as heart and lung transplantation, pneumonectomy, and ventricular assist device placement.
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PMID:Management of pulmonary hypertension in the operating room. 1753 16

The conditions of the protein-synthesizing system in neurons of the hippocampus (areas CA1 and C A3) and of the cortex (sensomotor region) in rats subjected to y-irradiation at a dose of 8 Gy under hypothermia (16 - 18 degrees C) and hypoxia-hypercapnia were investigated by fluorescent and electron microscopy. Under hypothermia, the protein-synthesizing system was shown to be damaged to a lesser degree and to be restored faster in comparison with similar neurons in rats irradiated at room temperature. In rats irradiated under hypothermia, the rRNA biogenesis and the protein-synthesizing activity of polyribosomes were restored in two days. The protective influence of hypothermia did not spread to changes in membrane structures (endoplasmic reticulum and Golgy apparatus); i.e., a partial loss of integrity and possible transformation of their structure caused by the irradiation and the restoration of these structures occurred at a lower rate.
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PMID:[Protective effect of hypothermia on brain neurons of rats exposed to ionizing radiation]. 1763 50

There is evidence that serotonin [5-hydroxytryptamine (5-HT)] is involved in the physiological responses to hypercapnia. Serotonergic neurons represent the major cell type (comprising 15-20% of the neurons) in raphe magnus nucleus (RMg), which is a medullary raphe nucleus. In the present study, we tested the hypothesis 1) that RMg plays a role in the ventilatory and thermal responses to hypercapnia, and 2) that RMg serotonergic neurons are involved in these responses. To this end, we microinjected 1) ibotenic acid to promote nonspecific lesioning of neurons in the RMg, or 2) anti-SERT-SAP (an immunotoxin that utilizes a monoclonal antibody to the third extracellular domain of the serotonin reuptake transporter) to specifically kill the serotonergic neurons in the RMg. Hypercapnia caused hyperventilation and hypothermia in all groups. RMg nonspecific lesions elicited a significant reduction of the ventilatory response to hypercapnia due to lower tidal volume (Vt) and respiratory frequency. Rats submitted to specific killing of RMg serotonergic neurons showed no consistent difference in ventilation during air breathing but had a decreased ventilatory response to CO(2) due to lower Vt. The hypercapnia-induced hypothermia was not affected by specific or nonspecific lesions of RMg serotonergic neurons. These data suggest that RMg serotonergic neurons do not participate in the tonic maintenance of ventilation during air breathing but contribute to the ventilatory response to CO(2). Ultimately, this nucleus may not be involved in the thermal responses to CO(2).
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PMID:Raphe magnus nucleus is involved in ventilatory but not hypothermic response to CO2. 1782 1

The management of critically ill children with traumatic brain injury (TBI) requires a precise assessment of the brain lesions but also of potentially associated extra-cranial injuries. Children with severe TBI should be treated in a pediatric trauma center, if possible. Initial assessment relies mainly upon clinical examination, trans-cranial Doppler ultrasonography and body CT scan. Neurosurgical operations are rarely necessary in these patients, except in the case of a compressive subdural or epidural hematoma. On the other hand, one of the major goals of resuscitation in these children is aimed at protecting against secondary brain insults (SBI). SBI are mainly because of systemic hypotension, hypoxia, hypercarbia, anemia and hyperglycemia. Cerebral perfusion pressure (CPP = mean arterial blood pressure - intracranial pressure: ICP) should be monitored and optimized as soon as possible, taking into account age-related differences in optimal CPP goals. Different general maneuvers must be applied in these patients early during their treatment (control of fever, avoidance of jugular venous outflow obstruction, maintenance of adequate arterial oxygenation, normocarbia, sedation-analgesia and normovolemia). In the case of increased ICP and/or decreased CPP, first-tier ICP-specific treatments may be implemented, including cerebrospinal fluid drainage, if possible, osmotic therapy and moderate hyperventilation. In the case of refractory intracranial hypertension, second-tier therapy (profound hyperventilation with P(a)CO(2) < 35 mmHg, high-dose barbiturates, moderate hypothermia, decompressive craniectomy) may be introduced, after a new cerebral CT scan.
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PMID:Management of critically ill children with traumatic brain injury. 1831 8

Increased tolerance to cerebral ischemia produced by general anesthesia during temporary carotid occlusion. By B. A. Wells, A. S. Keats, and D. A. Cooley. Surgery 1963; 54:216-23. Local anesthesia with little or no preoperative sedation is currently recommended as the anesthetic of choice for temporary carotid occlusion during carotid endarterectomy. Purported advantages include minimal circulatory and respiratory changes from the local anesthetic, and constant verbal contact can be maintained with the patient so that neurologic changes are promptly recognized. However, local anesthesia may not be satisfactory in uncooperative or semiconscious patients. We therefore undertook a trial of general anesthesia in 56 consecutive patients undergoing carotid endarterectomy. Patients were induced in standardized fashion using intravenous thiopental (100-400 mg), atropine (0.2 mg), and succinylcholine (40-80 mg). Cyclopropane, along with deliberate hypercapnia and hypertension, was used for anesthesia maintenance. All patients tolerated carotid occlusion for periods of up to 30 min during general anesthesia without shunt, bypass, or hypothermia. Except for one patient, electroencephalogram evidence of cerebral ischemia was not apparent during occlusion, and no patient suffered postoperative neurologic sequela. Twenty percent of patients who had their carotid arteries occluded preoperatively for 30-60 s without general anesthesia suffered convulsions. These data suggest that general anesthesia increased the tolerance to cerebral ischemia. Potential mechanisms involved might include: 1) decreased cerebral metabolic rate for oxygen; 2) increased cerebral blood flow from hypercapnia; 3) increased arterial oxygen tension; and 4) recruitment of new routes of collateral circulation.
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PMID:Contributions of anesthesiology to the surgical treatment of cerebrovascular disease: the role of Arthur S. Keats, M.D. 1836 8

The functional activity of the synthetic apparatus (parameter alpha) in blood lymphocytes, bone marrow hemopoietic cells, and thymus cells, as well as the total number of blood and bone marrow cells in rats after y-irradiation at a dose of 8 Gy in the conditions of normothermia and hypothermia (16-18 degrees C) with hypoxia-hypercapnia were investigated after 2 h and on days 1 and 4. The recovery processes in blood in both groups of rats after acute X-irradiation at a dose of 7 Gy for 36 days were analyzed too. Under hypothermia, on days 1-4 after acute gamma-irradiation, a decrease in the synthetic activity in remaining cells and devastation in the hemopoietic system were pronounced to a lesser degree. After X-irradiation, the restoration of synthetic activity in blood lymphocytes was shown to begin earlier and to finish faster in "hypothermic" rats as compared with the animals irradiated in the state of normothermia. The survival of "hypothermic" rats was 100% as compared with 30% in "normothermic" animals. Thus, the data show that hypothermia exerts a radioprotective effect on the cells of the immune and hemopoietic systems, thus enhancing the resistance of the organism to radiation.
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PMID:[The radioprotective effect of hypothermia on the immune and hematopoietic systems in mammals]. 1854 76

The presence of pulmonary arterial hypertension (PAH) is a significant predictor of major perioperative cardiovascular complications in patients undergoing cardiac diagnostic or interventional procedure or non cardiac surgery under sedation and/or anesthesia. Factors that precipitate a pulmonary hypertensive crisis include hypoxia, hypercarbia, acidosis, hypothermia, pain and airway manipulations. Pain management is challenging in patients with significant PAH. We report the use of dexmedetomidine for sedation and analgesia in a 16 year old patient with significant pulmonary hypertension, pneumonia and impending cardiorespiratory failure. This resulted in avoidance of endotracheal intubation and positive pressure ventilation, with subsequent recovery to discharge home.
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PMID:Novel use of dexmedetomidine in a patient with pulmonary hypertension. 1854 49

Few patients with cyanotic congenital heart disease reach adulthood without a cardiac operation. The prognosis for ''unrepaired'' pulmonary atresia with ventricular septal defect is approximately 8% in the 1st decade of age. Consequently, the number of adults with this particular heart disease (unrepaired) who are expected to need a non-cardiac surgery is extremely low. General anesthesia may aggravate the preexisting right to left shunt and lead to persistent severe hypoxemia. The goal of anesthetic management should be to maintain intravascular volume. Systemic and pulmonary vascular resistance changes, such as might occur due to acidosis, hypothermia, hypercarbia or excessive airway pressures, should be avoided. Maintenance of preload, contractility and sinus rhythm is of major importance. The complex pathophysiology of such heart disease, in addition to the circumstances of emergency operation, exacerbate the total anesthetic risk. We present here a rare case of an acute appendectomy with successful outcome in an adult with pulmonary atresia and ventricular septal defect.
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PMID:Appendectomy for an adult with cyanotic congenital heart disease. 1919 May 64

Traumatic brain injury (TBI) has been demonstrated to induce cerebral vascular dysfunction that is reflected in altered responses to various vasodilators. While previous reports have focused primarily on the short-term vascular alterations, few have examined these vascular changes for more than 7 days, or have attempted to correlate these alterations with any persisting behavioral changes or potential therapeutic modulation. Accordingly, we evaluated the long-term microvascular and behavioral consequences of experimental TBI and their therapeutic modulation via hypothermia. In this study, one group was injured with no treatment, another group was injured and 1 h later was treated with 120 min of hypothermia followed by slow rewarming, and a third group was non-injured. Animals equipped with cranial windows for visualization of the pial microvasculature were challenged with various vasodilators, including acetylcholine, hypercapnia, adenosine, pinacidil, and sodium nitroprusside, at either 1 or 3 weeks post-TBI. In addition, all animals were tested for vestibulomotor tasks at 1 week post-TBI, and animals surviving for 3 weeks post-TBI were tested in a Morris water maze (MWM). The results of this investigation demonstrated that TBI resulted in long-term vascular dysfunction in terms of altered vascular reactivity to various vasodilators, which was significantly improved with the use of a delayed 120-min hypothermic treatment. In contrast, data from the MWM task indicated that injured animals revealed persistent deficits in the spatial memory test performance, with hypothermia exerting no protective effects. Collectively, these data illustrate that TBI can evoke long-standing brain vascular and spatial memory dysfunction that manifest different responses to hypothermic intervention. These findings further illustrate the complexity of TBI and highlight the fact that the chosen hypothermic intervention may not necessarily exert a global protective response.
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PMID:The long-term microvascular and behavioral consequences of experimental traumatic brain injury after hypothermic intervention. 1924 7

To investigate the incidence of iatrogenic dyscarbia in survivors of out-of-hospital cardiac arrest treated with induced mild hypothermia.We performed a retrospective cohort study of the ventilatory management based on blood gas analyses of patients resuscitated from prehospital cardiac arrest. In the pilot phase, we assessed the ventilatory management in the patients treated in one university hospital during a 4-year study period. Subsequently, a more recent (1-year) retrospective cohort of resuscitated patients from all five Finnish university hospitals concerning the first 48h after hospital admission was analyzed. Core temperatures and temperature corrected (or non-corrected) blood gas analysis results with focus on carbon dioxide tension were analyzed. In addition, a survey was performed to investigate the ventilatory strategies in all Finnish hospitals providing mild hypothermia for cardiac arrest victims.The pilot cohort suggested a high incidence of hypo- or hyper-carbia during hypothermia treatment. In the multicenter patient population of 122 patients contributing a total of 1627 measurements, the PaCO(2) distribution was as follows: less than 4 kPa in 148 samples out of 1627 (9%), 4-4.6 kPa in 404 (25%), 4.7-6 kPa in 887 (55%) and more than 6 kPa in 188 samples (12%). There was a significant difference in the incidence of hypercarbia between the hospitals (p<0.05).We conclude that normocarbia was achieved/maintained only in approximately 55% of the samples. The incidence of hypo- or hyper-carbia (dyscarbia) was high (45%). This may predispose for serious derangements in the cerebral perfusion of the resuscitated patient. These results call for vigilance in adjustment of the ventilatory management to meet the needs of the patients treated with mild hypothermia.
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PMID:Incidence of iatrogenic dyscarbia during mild therapeutic hypothermia after successful resuscitation from out-of-hospital cardiac arrest. 1958 3


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