Fall In Core Body Temperature Research Articles

Comparison of effect of inhaled anaesthetic (Sevoflurane) versus intravenous (Propofol) anaesthetic on core and peripheral body temperature during general anaesthesia: A randomised control study

: The fall in core body temperature and peripheral body temperature following the administration of anaesthetic agent has been studied and demonstrated so far, along with the comparison of the same parameters following induction with propofol in contrast to that with sevoflurane. But no study so far, has compared the effects of TCI-propofol based anaesthesia with that of sevoflurane based anaesthesia for induction and maintenance, on core and peripheral body temperature and the gradient of temperature between the agents. The studies conducted so far, has shown more fall in core and peripheral body temperature from their respective baseline values when propofol was used for induction of anaesthesia in comparison to the use of sevoflurane. A total of 60 adults were randomized into two groups of 30 each; Group 1 were induced with TCI- propofol at 8mcg/ml plasma concentration and maintaind with TCI-propofol at 2-3mcg/ml plasma concentration and 66% nitrous oxide and 33% oxygen gas mixture. Group 2 were induced with intravenous thiopentone at 3-5mg/kg body weight and maintained with 1-1.5MAC sevoflurane, 66% nitrous oxide and 33% oxygen gas mixture. Core body temperature was measured inserting the temperature probe into nasophraynx and peripheral temperature was measured with the temperature probe inserted onto thenar eminence of either hand. We observed that both anaesthetic agents have caused similar fall in core temperature. However, peripheral temperature fell more with sevoflurane compared to TCI-propofol. In parallel with these observations, the increase in temperature gradient was higher in magnitude for sevoflurane based anaesthesia. The core temperature was comparable between the groups from their respective baseline values. But, the fall in peripheral temperature was more in sevoflurane group, so was the temperature gradient. Thus, TCI-propofol when used in appropriate plasma concentration for induction and maintenance of anaesthesia causes less hypothermia in contrast to sevoflurane.

The use of forced air warmer for the prevention of inadvertent perioperative hypothermia under general anaesthesia - A prospective observational study

Temperature is an important parameter which determines patient outcomes perioperatively. Iatrogenic hypothermia during surgery under general anaesthesia leads to significant side effects which can be corrected with the use of active body surface warming devices like the forced air warmer. A prospective observational study was conducted with a sample size of 362 which included patients of either sex aged 18-65years posted for any elective surgery under general anaesthesia lasting >60 and ≤180minutes. Baseline oral temperature was recorded preoperatively. Patients were warmed with forced air warmer intraoperatively at 44°C with half hourly monitoring of nasopharyngeal temperature until extubation. Intravenous fluids were given at room temperature. Further, oral temperature was monitored at 15 and 60 minutes in post anaesthesia care unit and patients were warmed if hypothermic or shivering. The final mean intraoperative temperature (nasopharyngeal) was 36.01⁰C (n=362) with a range from 34.7⁰C to 37.1⁰C. 139 of 362(n) (38.4%) patients were hypothermic (<36⁰C) at the end of surgery. 61.6% of patients were normothermic. In 9 patients (2.5%, n=362) the forced air warmer was turned off due to over heating (temperature >37⁰C). 33 patients (n=362, 9.1%) had shivering postoperatively. Comparing the nasopharyngeal temperature (mean) at half hourly intervals post induction revealed statistically significant results (p<0.001). The establishment of near constant temperature (36±0.03°C) following the initial fall in core body temperature can be attributed to the forced air warmer. However, it is imperative to continuously monitor core body temperature to detect temperature changes(hypo/hyperthermia) in order to use the device safely as chances of overheating is always present.

Cold-associated skin disorders

The human capacity for physiologic adaptation to cold is minimal. A cold environment can be a threat to the skin, leading to a subsequent fall in core body temperature. Many physiologic, behavioral, and environmental factors predispose to the global effects of cold injuries. Physical injuries caused by cold have two forms: systemic forms such as hypothermia and localized forms such as frostbite. Reduced temperature directly damages the tissue, as in frostbite and cold immersion foot. Vasospasm of vessels perfusing the skin induces chilblain, acrocyanosis, and frostbite. The degree of damage caused by cold is related to four factors: temperature, exposure time, wind intensity (temperature sensation), and high altitude.

Pepper and cinnamon improve cold induced cognitive impairment via increasing non-shivering thermogenesis; a study

Despite an understanding that a major effect of cold exposure is a fall in core body temperature which is responsible for the observed decrements in the performance, it is surprising that thermogenic supplements are seldom evaluated to verify if they can aid in improving the performance during cold exposure. Following evidence from our previous study indicating the ability of pepper and cinnamon to improve cold endurance, we investigated further here if the improved endurance had advantages in real time where they could positively affect cognitive performance (assessed by Novel object test) when exposed to cold in albino wistar rats. In order to delineate if the observed improvement if any, was due to their cognitive enhancing ability or thermogenic potential, distinctive room temperature (RT) and cold temperature (CT) groups were used. Cold exposure impaired cognitive performance which improved following treatment with both the spices. We noted an increased rate of cold adaptive thermogenesis in CT treated group as evidenced by an elevated norepinephrine, free fatty acid levels in blood, increased expression of UCP1 in brown adipose tissue, the net effect being a decreased fall in the core body temperature. Absence of any notable effect in these parameters in the RT treated group ascertained that at least in the current experimental set up the observed improvement in performance in CT treated group is due to the thermogenic potential of the spices alone. In conclusion, our results demonstrate that the cognitive impairment caused by exposure to cold can be effectively countered by agents with thermogenic potential.

Cold adaptive thermogenesis following consumption of certain pungent spice principles: A validation study

Identifying a means to activate or potentiate thermogenic mechanisms through ingestion of dietary compounds have important implications in cold endurance and survival. Although many reports discuss the thermogenic potential of spices, it is surprising that none of the studies verify whether consumption of spices can improve cold endurance. In this study, we have attempted to evaluate if ingestion of certain spices can activate heat-generating mechanisms in the body such that a fall in. core body temperature (CBT) can be delayed or prevented when faced with a cold challenge. Ten commonly used spices in the Indian cuisine were chosen and 70% ethanol extract of the spices were fed orally to male Wistar rats at a dose of 250mg/kg for a period of 7 days. A change in CBT during cold exposure was recorded before and after treatment. At the end of the experiment, plasma norepinephrine and serum free fatty acid levels were estimated. We observed that among the ten spices, treatment with cinnamon and pepper extracts showed significant improvement in comparison to the control group. Based on evidence in literature and the HPLC-MS analysis from our lab, we hypothesized that the effects of the pepper and cinnamon extracts might be due to their piperine and cinnamaldehyde content respectively. However, no improved endurance was observed when they were administered alone. Poor endurance following depletion of endogenous norepinephrine levels using reserpine indicated its involvement in mediating the heat generating processes. However, it is noteworthy that green tea and spice treated animals exhibited a fall in CBT which was lower than their initial fall. In conclusion, our findings provide experimental evidence that ingestion of spices, viz., pepper and cinnamon, might elicit thermogenic responses such that hypothermia can be delayed or prevented upon cold exposure.

Ondansetron and promethazine have differential effects on hypothermic responses to lithium chloride administration and to provocative motion in rats

We recently reported that provocative motion (rotation in a home cage) causes hypothermic responses in rats, similar to the hypothermic responses associated with motion sickness in humans. Many stimuli inducing emesis in species with an emetic reflex also provoke hypothermia in the rat, therefore we hypothesized that a fall in body temperature may reflect a “nausea-like” state in these animals. As rats do not possess an emetic reflex, we employed a pharmacological approach to test this hypothesis. In humans, motion- and chemically-induced nausea have differential sensitivity to anti-emetics. We thus tested whether the hypothermia induced in rats by provocative motion (rotation at 0.7 Hz) and by the emetic LiCl (63 mg/kg i.p.) have a similar differential pharmacological sensitivity. Both provocations caused a comparable robust fall in core body temperature (−1.9 ± 0.3°C and −2.0 ± 0.2°C for chemical and motion provocations, respectively). LiCl−induced hypothermia was completely prevented by ondansetron (2mg/kg, i.p., a 5-HT3 receptor antagonist that reduces cancer chemotherapy-induced nausea and vomiting), but was insensitive to promethazine (10 mg/kg, i.p., a predominantly histamine-H1 and muscarinic receptor antagonist that is commonly used to treat motion sickness). Conversely, motion-induced hypothermia was unaffected by ondansetron but promethazine reduced the rate of temperature decline from 0.20 ± 0.02 to 0.11 ± 0.03°C/min (P < 0.05) with a trend to decrease the magnitude. We conclude that this differential pharmacological sensitivity of the hypothermic responses of vestibular vs. chemical etiology in rats mirrors the observations in other pre-clinical models and humans, and thus supports the idea that a “nausea-like” state in rodents is associated with disturbances in thermoregulation.

Insulin mediates the linkage acceleration of muscle protein synthesis, thermogenesis, and heat storage by amino acids

Amino acid (AA) administration can stimulate heat accumulation in the body, as especially found under anesthetic conditions. To test our hypothesis that marked rise in plasma insulin concentrations following AA administration plays an important role in the heat storage, we intravenously administered either a balanced AA mixture or saline over 3h, both with and without a primed-constant infusion of somatostatin in propofol-anesthetized rats. Rats on AA but lacking marked rise in plasma insulin by somatostatin treatment failed to show: attenuation of fall in core body temperature; partial increases in oxygen consumption; and stimulated muscle protein synthesis. Furthermore, the AA’s stimulatory effects on phosphorylation of mTOR, 4E-BP1, and S6K1 were partially blocked by somatostatin. Our findings strongly suggest that the marked rise in insulin following AA administration promote translation initiation activities and stimulate muscle protein synthesis, which facilitates heat accumulation in the body.

ECG J waves

Osborne waves, also referred to as J waves, were Þ rst described by Tomaszewkski in 1938. The J wave is a positive convex des ection that occurs at the junction of the QRS complex and ST segment, the J-point. They occur most prominently in the inferior leads: II, III, and aVF and the precordial leads: V5–V6 when the core body temperature falls below 32°C (89.6°F). The magnitude of the des ection above the isoelectric line varies inversely with the fall in core body temperature below 32°C. Computer interpretation of ECG has been found to be unreliable in hypothermia, with the J waves in some cases being mistaken for myocardial injury current. When J waves are seen the differential diagnosis includes hypercalcemia, sepsis, CNS lesion, cardiac ischemia, and Brugada syndrome.

Accidental hypothermia

Hypothermia can be defined as an unintentional fall in core body temperature below 35°C.1 It can be classified as mild (core body temperature 32.2-35°C), moderate (< 32.2-28°C), or severe (<...

Nicotine-induced hypothermia through an indirect dopaminergic mechanism

The effect of nicotine on core body temperature was studied in mice. Intraperitoneal (i.p.) injection of nicotine (0.5, 1 and 2 mg/kg) induced a dose-dependent hypothermia. The response was inhibited by reserpine (5 mg/kg), the centrally active nicotinic receptor antagonist mecamylamine (0.1-1 mg/kg) and the D-2 dopamine receptor antagonist sulpiride (25-100 mg/kg). The β-adrenoceptor antagonist propranolol (5 and 10 mg/kg) and the serotonergic blocker methysergide (5 and 10 mg/kg) did not inhibit but increased the nicotine response. The α-adrenoceptor antagonist phenoxybenzamine, the antimuscarinic agent atropine, the D-1 dopamine receptor antagonist SCH 23390, the peripheral dopamine antagonist domperidone and the peripheral nicotinic antagonist hexamethonium did not alter the nicotine-induced hypothermia. It is concluded that nicotine may cause a fall in core body temperature through a central dopaminergic mechanism.

Voluntary hypometabolism in an indian yogi

1. 1. It has been claimed that Indian yogis can voluntarily become hypometabolic ( bhoogarbha samadhi) in a sealed underground chamber as a means of remaining in a mediative state for multiday periods. 2. 2. To investigate this claim we obtained cooperation of a practitioner of bhoogarbha samadhi. In an open flow system, we measured his resting rate of oxygen consumption and also his oxygen consumption rate over a 5 h period during which he was requested to display his abilities to become hypometabolic as if he were in bhoogarbha samadhi. 3. 3. The yogi's resting O 2 consumption was 3.06 ml O 2kg -1 min 1 and his O 2 consumption over a 4h period of meditation was 1.85±0.26 ml O 2kg -1min -1, a reduction of 40%. 4. 4. At the beginning of the mediation there was a peripheral vasodilation and a fall in core body temperature of 0.4°C. These events were reversed at the end of the meditation period. 5. 5. This study confirms that Indian yogis can enter a state of self-induced hypometabolism, but the mechanisms remain unknown.