Hypothermia Prevention During Surgery: Comparison Between Thermal Mattress And Thermal Blanket


This study aimed to compare the efficiency of the thermal blanket and thermal mattress in the prevention of hypothermia during surgery. Thirty-eight randomized patients were divided into two groups (G1 – thermal blanket and G2 - thermal mattress). The variables studied were: length of surgery, length of stay in the post-anesthetic care unit, period without using the device after thermal induction, transport time from the operating room to post-anesthetic care unit, intraoperative fluid infusion, surgery size, anesthetic technique, age, body mass index, esophageal, axillary and operating room temperature. In G2, length of surgery and starch infusion longer was higher (both p=0.03), but no hypothermia occurred. During the surgical anesthetic procedure, the axillary temperature was higher at 120 minutes (p=0.04), and esophageal temperature was higher at 120 (p=0.002) and 180 minutes (p=0.03) and at the end of the procedure (p=0.002). The thermal mattress was more effective in preventing hypothermia during surgery.

Ethanol-induced hypothermia in rats is antagonized by dexamethasone

The effect of dexamethasone on ethanol-induced hypothermia was investigated in 3.5-month old male Wistar rats (N = 10 animals per group). The animals were pretreated with dexamethasone (2.0 mg/kg, ip; volume of injection = 1 ml/kg) 15 min before ethanol administration (2.0, 3.0 and 4.0 g/kg, ip; 20% w/v) and the colon temperature was monitored with a digital thermometer 30, 60 and 90 min after ethanol administration. Ethanol treatment produced dose-dependent hypothermia throughout the experiment (-1.84 ± 0.10, -2.79 ± 0.09 and -3.79 ± 0.15oC for 2.0, 3.0 and 4.0 g/kg ethanol, respectively, 30 min after ethanol) but only the effects of 2.0 and 3.0 g/kg ethanol were significantly antagonized (-0.57 ± 0.09 and -1.25 ± 0.10, respectively, 30 min after ethanol) by pretreatment with dexamethasone (ANOVA, P<0.05). These results are in agreement with data from the literature on the rapid antagonism by glucocorticoids of other effects of ethanol. The antagonism was obtained after a short period of time, suggesting that the effect of dexamethasone is different from the classical actions of corticosteroids

Role of nitric oxide in hypoxia-induced hyperventilation and hypothermia: participation of the locus coeruleus

Hypoxia elicits hyperventilation and hypothermia, but the mechanisms involved are not well understood. The nitric oxide (NO) pathway is involved in hypoxia-induced hypothermia and hyperventilation, and works as a neuromodulator in the central nervous system, including the locus coeruleus (LC), which is a noradrenergic nucleus in the pons. The LC plays a role in a number of stress-induced responses, but its participation in the control of breathing and thermoregulation is unclear. Thus, in the present study, we tested the hypothesis that LC plays a role in the hypoxia-induced hypothermia and hyperventilation, and that NO is involved in these responses. Electrolytic lesions were performed bilaterally within the LC in awake unrestrained adult male Wistar rats weighing 250-350 g. Body temperature and pulmonary ventilation (VE) were measured. The rats were divided into 3 groups: control (N = 16), sham operated (N = 7) and LC lesioned (N = 19), and each group received a saline or an NG-nitro-L-arginine methyl ester (L-NAME, 250 µg/µl) intracerebroventricular (icv) injection. No significant difference was observed between control and sham-operated rats. Hypoxia (7% inspired O2) caused hyperventilation and hypothermia in both control (from 541.62 ± 35.02 to 1816.18 ± 170.7 and 36.3 ± 0.12 to 34.4 ± 0.09, respectively) and LC-lesioned rats (LCLR) (from 694.65 ± 63.17 to 2670.29 ± 471.33 and 36 ± 0.12 to 35.3 ± 0.12, respectively), but the increase in VE was higher (P<0.05) and hypothermia was reduced (P<0.05) in LCLR. L-NAME caused no significant change in VE or in body temperature under normoxia, but abolished both the hypoxia-induced hyperventilation and hypothermia. Hypoxia-induced hyperventilation was reduced in LCLR treated with L-NAME. L-NAME also abolished the hypoxia-induced hypothermia in LCLR. The present data indicate that hypoxia-induced hyperventilation and hypothermia may be related to the LC, and that NO is involved in these responses.

A comparative study of severe scorpion envenomation in children caused by Tityus bahiensis and Tityus serrulatus

From January 1984 to May 1994, 17 of 239 children under 15 years old stung by Tityus serrulatus (15.1%) or Tityus bahiensis (84.9%) presented severe envenoming. Of these 17 patients (1-11 years old; median=2 yr) 14 were stung by T.serrulatus and three by T.bahiensis. All of them received scorpion antivenom i.v. at times ranging from 45 min. to 5 h after the accident (median=2h). On admission, the main clinical manifestations and laboratory and electrocardiographic changes were: vomiting (17), diaphoresis (15), tachycardia (14), prostration (10), tachypnea (8), arterial hypertension (7), arterial hypotension (5), tremors (5), hypothermia (4), hyperglycemia (17), leukocytosis (16/16), hypokalemia (13/17), increased CK-MB enzyme activity (>6% of the total CK, 11/12), hyperamylasemia (11/14), sinusal tachycardia (16/17) and a myocardial infarction-like pattern (11/17). Six patients stung by T.serrulatus had depressed left ventricular systolic function assessed by means of echocardiography. Of these, five presented pulmonary edema and four had shock. A child aged two-years old presented severe respiratory failure and died 65 h after being stung by T.serrulatus. Severe envenomations caused by T.serrulatus were 26.2 times more frequent than those caused by T.bahiensis (p<0.001).

Unusual abdominal tumors with intracardiac extension. Two cases with successful surgical resection

Abdominal tumors that can grow through vascular lumen and spread to the right heart are rare. Although these tumors have different histologic aspects, they may cause similar abdominal and cardiac symptoms and are a serious risk factor for pulmonary embolism and sudden death when they reach the right atrium and tricuspid valve. The best treatment is radical surgical resection of the entire tumor using cardiopulmonary bypass with or without deep hypothermia and total circulatory arrest. We report the cases of two patients, the first with leiomyosarcoma of the inferior vena cava and the other with intravenous leiomyomatosis of the uterus that showed intravascular growth up to right atrium and ventricle, who underwent successful radical resection in a one-stage procedure with the use of cardiopulmonary bypass. We discuss the clinical and histologic aspects and imaging diagnosis and review the literature.

Bilateral carotid endarterectomy combined with myocardial revascularization during the same surgical act

The best surgical approach for the treatment of patients with severe cerebral artery disease and simultaneous serious coronary artery disease still remains controversial. In this report we present a case of a 72-year-old female patient admitted to the hospital with unstable angina. Triple coronary artery obstructive disease and severe bilateral carotid artery stenosis were diagnosed. A combined, simultaneous surgical procedure was performed. After total circulatory by-pass with a membrane oxygenator, the patient's body temperature was lowered to 32°C. During the cool-down period, three proximal anastomoses of segments of autologous saphenous veins were performed in the ascending aorta. Immediately afterwards, bilateral carotid endarterectomy was performed, followed by three distal anastomoses to coronary arteries. The patient showed a satisfactory post-operative outcome. It was concluded that the combination of moderate hypothermia, hemodilution with appropriate hemodynamic control, as used in this patient, was an effective method of cerebral protection. The simultaneous approach of carotid endarterectomy and coronary artery by-pass surgery should be seen as a safe option for the treatment of this type of patient.

Surgical repair of a pseudoaneurysm of the ascending aorta after aortic valve replacement

We report the case of a patient with a pseudoaneurysm of the ascending aortic clinically diagnosed 5 months after surgical replacement of the aortic valve. Diagnosis was confirmed with the aid of two-dimensional echocardiography and helicoidal angiotomography. The corrective surgery, which consisted of a reinforced suture of the communication with the ascending aorta after opening and aspiration of the cavity of the pseudoaneurysm, was successfully performed through a complete sternotomy using extracorporeal circulation, femorofemoral cannulation, and moderate hypothermia, with no aortic clamping.

Influence of ischemic preconditioning in myocardial protection in patients undergoing myocardial revascularization with intermittent crossclamping of the aorta. Analysis of ions and blood gases

OBJECTIVE: To test the hypothesis that short periods of ischemia may increase the myocardial protection obtained with intermittent crossclamping of the aorta. METHODS: In the control group (18 patients), surgery was performed with systemic hypothermia at 32ºC and intermittent crossclamping of the aorta. Extracorporeal circulation was used. In the preconditioning group (17 patients), 2 crossclampings of the aorta lasting 3min each were added prior to the intermittent crossclamping of the conventional technique with an interval of 2min of reperfusion between them. Blood samples for analyses of pH, pCO2, pO2, sodium, potassium, calcium, and magnesium were obtained from the coronary sinus at the beginning of extracorporeal circulation (time 1), at the end of the first anastomosis (time 2), and at the end of extracorporeal circulation (time 3). RESULTS: No difference was observed in the results of the 2 groups, except for a variation in the ionic values in the different times of blood withdrawal; sodium values, however, remained stable. All patients had a good clinical outcome. CONCLUSION: The results of intermittent crossclamping of the aorta with moderate hypothermia were not altered by the use of ischemic preconditioning.

Cirurgia para controle do dano: uma revisão

Damage control surgery is one of the major advances in surgical practice in the last 20 years. The indications for damage control surgery are: the need to terminate a laparotomy rapidly in an exsanguinating, hypothermic patient who had developed a coagulopathy and who is about to die on the operating table; inability to control bleeding by direct hemostasis; and inability to close the abdomen without tension because of massive visceral edema and a tense abdominal wall. Damage control surgery has three phases: 1) laparotomy to control hemorrhage by packing, shunting, or balloon tamponade, or both; control of intestinal spillage by resection or ligation of damaged bowel, or both; 2) physiological resuscitation to correct hypothermia, metabolic acidosis, and coagulopathy. 3) planned reoperation for definitive repair. Damage control surgery is appropriate in a small number of critically ill patients who are likely to require substantial hospital resources. However, there are many questions that need to be answered. Who is the patient elected for this surgery? When is the ideal time to make the decision? Which are the parameters that indicate to the surgeons the moment to re-operate the patient? How to treat the long-term complications? In the present review we described some historical aspects, indications, technical aspects, advantages and disadvantages of this procedure, as well as its physiological consequences and morbidity and mortality rates of damage control surgery. Damage control surgery offers a simple effective alternative to the traditional surgical management of complex or multiple injuries in critically injured patients.

Experimental intoxication by the leaves of Melia azedarach (Meliaceae) in cattle

Green leaves of Melia azedarach were administered at single doses ranging from 5 to 30 g/kg bw to 11 calves. Clinical signs were depression, ruminal stasis, dry feces with blood, ataxia, muscle tremors, sternal recumbency, hypothermia and abdominal pain. Serum AST and CPK were increased. Signs appeared from 8 to 24 hours after dosing, and the clinical course lasted from 2 to 72 hours. Three calves dosed with 30g/kg bw died. The macroscopic findings included intestinal congestion, yellow discoloration of the liver, brain congestion and dry feces with blood in the rectum. The liver showed swollen and vacuolated hepatocytes. Necrotic hepatocytes were scattered throughout the parenchyma or concentrated in the periacinar zone. Degenerative and necrotic changes were observed in the epithelium of the forestomachs. There was also necrosis of the lymphoid tissue. Skeletal muscles showed hyaline degeneration and fiber necrosis. The necrotic fragments contained floccular or granular debris with infiltration by macrophages and satellite cells.

Effects of laparoscopy on the cardiorespiratory system of brown brocket deer (Mazama gouazoubira) anesthetized with ketamine/ xylazine/ midazolam combination and isoflurane

Laparoscopy is not widely used as a tool to perform assisted reproduction techniques in South American cervids; thus, scarce information in literature is available regarding its effects and appropriate anesthetic protocols to perform it. This study evaluated the effect of laparoscopy on heart rate (HR), respiration rate (RR), saturation of oxyhemoglobin (SpO2) and rectal temperature (RT) of six female brown brocket deer (Mazama gouazoubira) anesthetized with ketamine (5mg/kg), xylazine (0.3mg/kg), midazolam (0.5mg/kg) combination i.v. and isoflurane. Twelve laparoscopies were performed and each animal was used twice with a 40-day interval. After anesthetized, the animals were placed in dorsal recumbency to perform laparoscopy procedure using abdominal CO2 insufflations (14.2 ± 2.39mmHg; M ± SE). The main events of the laparoscopy procedure were divided into three periods: animal without (P1) and with abdominal insufflation (P2) and abdominal insufflation with the hips raised at 45º (P3). As a control, the animals were anesthetized again 40 days after the last laparoscopy, and were maintained in a dorsal recumbency for the same average duration of the previous anesthesia and no laparoscopy procedure was conducted. The period of anesthesia for the controls was also divided into P1, P2, and P3 considering the average duration of these periods in previous laparoscopies performed. Data were analyzed through the (ANOVA) variance analysis followed by Tukey test and values at P<0.05 were considered significant. No significant differences were observed in the parameters evaluated at P1, P2 and P3 between the animals submitted to laparoscopy and control. However, the RR mean between P1 (38.8 ± 4.42) and P3 (32.7 ± 4.81); and the RT mean between the P1 (38.2ºC ± 0.17), P2 (37.6ºC ± 0.19) and P3 (37.0ºC ± 0.21) varied significantly, independent of the laparoscopy. These data indicated that laparoscopy didn't cause any significant alterations in the cardiorespiratory parameters evaluated, even though the anesthetic protocol used can cause a reduction in the RT contributing to development of hypothermia during anesthesia.

Effects of a neuronal nitric oxide synthase inhibitor on lipopolysaccharide-induced fever

It has been demonstrated that nitric oxide (NO) has a thermoregulatory action, but very little is known about the mechanisms involved. In the present study we determined the effect of neuronal nitric oxide synthase (nNOS) inhibition on thermoregulation. We used 7-nitroindazole (7-NI, 1, 10 and 30 mg/kg body weight), a selective nNOS inhibitor, injected intraperitoneally into normothermic Wistar rats (200-250 g) and rats with fever induced by lipopolysaccharide (LPS) (100 µg/kg body weight) administration. It has been demonstrated that the effects of 30 mg/kg of 7-NI given intraperitoneally may inhibit 60% of nNOS activity in rats. In all experiments the colonic temperature of awake unrestrained rats was measured over a period of 5 h at 15-min intervals after intraperitoneal injection of 7-NI. We observed that the injection of 30 mg/kg of 7-NI induced a 1.5oC drop in body temperature, which was statistically significant 1 h after injection (P<0.02). The coinjection of LPS and 7-NI was followed by a significant (P<0.02) hypothermia about 0.5oC below baseline. These findings show that an nNOS isoform is required for thermoregulation and participates in the production of fever in rats.

Implications of ischemic penumbra for the diagnosis of brain death

The data reviewed here suggest the possibility that a global reduction of blood supply to the whole brain or solely to the infratentorial structures down to the range of ischemic penumbra for several hours or a few days may lead to misdiagnosis of irreversible brain or brain stem damage in a subset of deeply comatose patients with cephalic areflexia. The following proposals are advanced: 1) the lack of any set of clinically detectable brain functions does not provide a safe diagnosis of brain or brain stem death; 2) apnea testing may induce irreversible brain damage and should be abandoned; 3) moderate hypothermia, antipyresis, prevention of arterial hypotension, and occasionally intra-arterial thrombolysis may contribute to good recovery of a possibly large subset of cases of brain injury currently regarded as irreversible; 4) confirmatory tests for brain death should not replace or delay the administration of potentially effective therapeutic measures; 5) in order to validate confirmatory tests, further research is needed to relate their results to specific levels of blood supply to the brain. The current criteria for the diagnosis of brain death should be revised.

Dopaminergic profile of new heterocyclic N-phenylpiperazine derivatives

Dopamine constitutes about 80% of the content of central catecholamines and has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinson's disease, depression and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to report the structural design of two N-phenylpiperazine derivatives, compound 4: 1-[1-(4-chlorophenyl)-1H-4-pyrazolylmethyl]-4-phenylhexahydropyrazine and compound 5: 1-[1-(4-chlorophenyl)-1H-1,2,3-triazol-4-ylmethyl]-4-phenylhexahydropyrazine, planned to be dopamine ligands, and their dopaminergic action profile. The two compounds were assayed (dose range of 15-40 mg/kg) in three experimental models: 1) blockade of amphetamine (30 mg/kg, ip)-induced stereotypy in rats; 2) the catalepsy test in mice, and 3) apomorphine (1 mg/kg, ip)-induced hypothermia in mice. Both derivatives induced cataleptic behavior (40 mg/kg, ip) and a hypothermic response (30 mg/kg, ip) which was not prevented by haloperidol (0.5 mg/kg, ip). Compound 5 (30 mg/kg, ip) also presented a synergistic hypothermic effect with apomorphine (1 mg/kg, ip). Only compound 4 (30 mg/kg, ip) significantly blocked the amphetamine-induced stereotypy in rats. The N-phenylpiperazine derivatives 4 and 5 seem to have a peculiar profile of action on dopaminergic functions. On the basis of the results of catalepsy and amphetamine-induced stereotypy, the compounds demonstrated an inhibitory effect on dopaminergic behaviors. However, their hypothermic effect is compatible with the stimulation of dopaminergic function which seems not to be mediated by D2/D3 receptors.

Cardiopulmonary bypass alters the pharmacokinetics of propranolol in patients undergoing cardiac surgery

The pharmacokinetics of propranolol may be altered by hypothermic cardiopulmonary bypass (CPB), resulting in unpredictable postoperative hemodynamic responses to usual doses. The objective of the present study was to investigate the pharmacokinetics of propranolol in patients undergoing coronary artery bypass grafting (CABG) by CPB under moderate hypothermia. We evaluated 11 patients, 4 women and 7 men (mean age 57 ± 8 years, mean weight 75.4 ± 11.9 kg and mean body surface area 1.83 ± 0.19 m²), receiving propranolol before surgery (80-240 mg a day) and postoperatively (10 mg a day). Plasma propranolol levels were measured before and after CPB by high-performance liquid chromatography. Pharmacokinetic Solutions 2.0 software was used to estimate the pharmacokinetic parameters after administration of the drug pre- and postoperatively. There was an increase of biological half-life from 4.5 (95% CI = 3.9-6.9) to 10.6 h (95% CI = 8.2-14.7; P < 0.01) and an increase in volume of distribution from 4.9 (95% CI = 3.2-14.3) to 8.3 l/kg (95% CI = 6.5-32.1; P < 0.05), while total clearance remained unchanged 9.2 (95% CI = 7.7-24.6) vs 10.7 ml min-1 kg-1 (95% CI = 7.7-26.6; NS) after surgery. In conclusion, increases in drug distribution could be explained in part by hemodilution during CPB. On the other hand, the increase of biological half-life can be attributed to changes in hepatic metabolism induced by CPB under moderate hypothermia. These alterations in the pharmacokinetics of propranolol after CABG with hypothermic CPB might induce a greater myocardial depression in response to propranolol than would be expected with an equivalent dose during the postoperative period.