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1.  Effect of preoperative warming during cesarean section under spinal anesthesia 
Korean Journal of Anesthesiology  2012;62(5):454-460.
Postoperative hypothermia and shivering is a frequent event in patients during cesarean section under spinal anesthesia. We assessed the effect of preoperative warming during cesarean delivery under spinal anesthesia for prevention of hypothermia and shivering.
Forty five patients undergoing elective cesarean section were randomly assigned to three groups. Group F received warmed intravenous fluid (40℃). Group A patients were actively warmed by forced air-warming. Group C was the control group. Forced air-warming and warmed fluid was maintained for the 15 min preceding spinal anesthesia. Core temperature (tympanic membrane) and the skin temperature of arm and thigh were measured and shivering was graded simultaneously.
The core temperature at 45 min decreased less in Groups F and A than Group C (-0.5℃ ± 0.3℃ vs -0.6℃ ± 0.4℃ vs -0.9℃ ± 0.4℃, respectively; P = 0.004). The arm temperature at 15 min and 30 min exhibited a greater increase in Group A than Group F and Group C (P = 0.001 and P = 0.012, respectively). Leg temperature increased similarly among the three groups. The incidence of shivering was significantly less in Group A and Group F than Group C (20%, 13.3%, and 53.3%, respectively; P = 0.035).
Preoperative forced air-warming and warmed fluid prevents hypothermia and shivering in patients undergoing elective cesarean delivery with spinal anesthesia.
PMCID: PMC3366313  PMID: 22679543
Cesarean section; Shivering; Spinal anesthesia; Warming
2.  Are active warming measures required during paediatric cleft surgeries? 
Indian Journal of Anaesthesia  2013;57(4):377-380.
During paediatric cleft surgeries intraoperative heat loss is minimal and hence undertaking all possible precautions available to prevent hypothermia and use of active warming measures may result in development of hyperthermia. This study aims to determine whether there will be hyperthermia on active warming and hypothermia if no active warming measures are undertaken. The rate of intraoperative temperature changes with and without active warming was also noted.
This study was conducted on 120 paediatric patients undergoing cleft lip and palate surgeries. In Group A, forced air warming at 38°C was started after induction. In Group B, no active warming was done. Body temperature was recorded every 30 min starting after induction until 180 min or end of surgery. Intragroup comparison of variables was done using Paired sample test and intergroup comparison using independent sample t-test.
In Group A, all intraoperative temperature readings were significantly higher than baseline. In Group B, there was a significant reduction in temperature at 30 and 60 min. Temperature at 90 min did not show any significant difference, but further readings were significantly higher. Maximum rise in temperature occurred in Group A between 120 and 150 min and maximum fall in temperature in Group B was seen during first 30 min.
In pediatric cleft surgeries, we recommend active warming during the first 30 minutes if the surgery is expected to last for <2h, and no such measures are required if the expected duration is >2h.
PMCID: PMC3800330  PMID: 24163452
Active warming; hyperthermia; hypothermia; paediatric cleft surgeries
3.  The effect of warmed inspired gases on body temperature during arthroscopic shoulder surgery under general anesthesia 
Perioperative hypothermia can develop easily during shoulder arthroscopy, because cold irrigation can directly influence core body temperature. The authors investigated whether active warming and humidification of inspired gases reduces falls in core body temperature and allows redistribution of body heat in patients undergoing arthroscopic shoulder surgery under general anesthesia.
Patients scheduled for arthroscopic shoulder surgery were randomly assigned to receive either room temperature inspired gases using a conventional respiratory circuit (the control group, n = 20) or inspired gases humidified and heated using a humidified and electrically heated circuit (HHC) (the heated group, n = 20).
Core temperatures were significantly lower in both groups from 30 min after anesthesia induction, but were significantly higher in the heated group than in the control group from 75 to 120 min after anesthesia induction.
In this study the use of a humidified and electrically heated circuit did not prevent core temperature falling during arthroscopic shoulder surgery, but it was found to decrease reductions in core temperature from 75 min after anesthesia induction.
PMCID: PMC3726840  PMID: 23904934
Arthroscopy; Circuit; General anesthesia; Shoulder; Temperature
4.  Effect of warm intravenous and irrigating fluids on body temperature during transurethral resection of the prostate gland 
BMC Urology  2007;7:15.
Transurethral resection of the prostate gland with irrigation fluid at room temperature leads to perioperative hypothermia which could give rise to adverse cardiovascular events in the perioperative period. The use of isothermic irrigation fluid reduces but does not eliminate this risk. Routine use of warm intravenous fluids along with isothermic irrigation had not been documented. This study set out to investigate the effect of the use of warm intravenous fluid together with isothermic irrigation fluid on the body temperature in patients undergoing transurethral resection of the prostate gland.
One hundred and twenty consented patients with obstructing benign prostatic hyperplasia were randomly assigned to one of 3 groups. Group 1 received irrigation and intravenous fluids at room temperature, group 2 received warmed irrigation fluid at 38°C along with intravenous fluid at room temperature while group 3 patients received warmed irrigation fluid and warmed intravenous fluids at 38°C. Their perioperative body temperature changes were monitored, analyzed and compared.
The mean decrease in body temperature at the end of the procedure was significantly greater in group 1 (0.98 ± 0.56°C) than in group 2 (0.42 ± .21°C) (p < 0.001). Significantly more patients in group 1 also experienced shivering. However, in group 3, there was no significant change in the mean body temperature (p > 0.05) and none of them felt cold or shivered.
It is concluded that the use of isothermic irrigation fluid together with warm intravenous fluids during TURP prevents the occurrence of perioperative hypothermia.
Trial registration number
PMCID: PMC2034579  PMID: 17877827
5.  Water warming garment versus forced air warming system in prevention of intraoperative hypothermia during liver transplantation: a randomized controlled trial [ISRCTN32154832] 
BMC Anesthesiology  2002;2:7.
The authors compared two strategies for the maintenance of intraoperative normothermia during orthotopic liver transplantation (OLT): the routine forced-air warming system and the newly developed, whole body water garment.
In this prospective, randomized and open-labelled study, 24 adult patients were enrolled in one of two intraoperative temperature management groups during OLT. The water-garment group (N = 12) received warming with a body temperature (esophageal) set point of 36.8°C. The forced air-warmer group (N = 12) received routine warming therapy using upper- and lower-body forced-air warming system. Body core temperature (primary outcome) was recorded intraoperatively and during the two hours after surgery in both groups.
The mean core temperatures during incision, one hour after incision and during the skin closing were significantly higher (p < 0.05, t test with Bonferroni corrections for the individual tests) in the water warmer group compared to the control group (36.7 ± 0.1, 36.7 ± 0.2, 36.8 ± 0.1 vs 36.1 ± 0.4, 36.1 ± 0.4, 36.07 ± 0.4°C, respectively). Moreover, significantly higher core temperatures were observed in the water warmer group than in the control group during the placement of cold liver allograft (36.75 ± 0.17 vs 36.09 ± 0.38°C, respectively) and during the allograft reperfusion period (36.3 ± 0.26 vs 35.52 ± 0.42°C, respectively). In addition, the core temperatures immediately after admission to the SICU (36.75 ± 0.13 vs 36.22 ± 0.3°C, respectively) and at one hr (36.95 ± 0.13 vs 36.46 ± 0.2°C, respectively) were significantly higher in the water warmer group, compared to the control group, whereas the core temperature did not differ significantly afte two hours in ICU in both groups.
The investigated water warming system results in better maintenance of intraoperative normothermia than routine air forced warming applied to upper- and lower body.
PMCID: PMC137608  PMID: 12441007
6.  Rewarming of healthy volunteers after induced mild hypothermia: a healthy volunteer study 
Emergency Medicine Journal : EMJ  2005;22(3):182-184.
Objectives: The study compares the efficacy of two active and one passive warming interventions in healthy volunteers with induced mild hypothermia.
Methods: Eight volunteers were studied in a random order crossover design. Each volunteer was studied during re-warming from a core temperature of 35°C with each of: a radiant warmer (Fisher & Paykel); a forced air warmer (Augustine Medical), and a polyester filled blanket, to re-warm.
Results: No significant differences in re-warming rates were observed between the three warming devices. It was found that the subject's endogenous heat production was the major contributor to the re-warming of these volunteers. Metabolic rates of over 350 W were seen during the study.
Conclusions: For patients with mild hypothermia and in whom shivering is not contraindicated our data would indicate that the rate of re-warming would be little different whether a blanket or one of the two active devices were used. In the field, this may provide the caregiver a useful choice.
PMCID: PMC1726709  PMID: 15735265
7.  Intensified thermal management for patients undergoing transcatheter aortic valve implantation (TAVI) 
Transcatheter aortic valve implantation via the transapical approach (TAVI-TA) without cardiopulmonary bypass (CPB) is a minimally invasive alternative to open-heart valve replacement. Despite minimal exposure and extensive draping perioperative hypothermia still remains a problem.
In this observational study, we compared the effects of two methods of thermal management on the perioperative course of core temperature. The methods were standard thermal management (STM) with a circulating hot water blanket under the patient, forced-air warming with a lower body blanket and warmed infused fluids, and an intensified thermal management (ITM) with additional prewarming using forced-air in the pre-operative holding area on the awake patient.
Nineteen patients received STM and 20 were treated with ITM. On ICU admission, ITM-patients had a higher core temperature (36.4 ± 0.7°C vs. 35.5 ± 0.9°C, p = 0.001), required less time to achieve normothermia (median (IQR) in min: 0 (0-15) vs. 150 (0-300), p = 0.003) and a shorter period of ventilatory support (median (IQR) in min: 0 (0-0) vs. 246 (0-451), p = 0.001).
ITM during TAVI-TA reduces the incidence of hypothermia and allows for faster recovery with less need of ventilatory support.
PMCID: PMC3203847  PMID: 21943183
Transcatheter aortic valve implantation; hypothermia; thermal management; core temperature; prewarming; forced air warming
8.  The effect of active warming in prehospital trauma care during road and air ambulance transportation - a clinical randomized trial 
Prevention and treatment of hypothermia by active warming in prehospital trauma care is recommended but scientifical evidence of its effectiveness in a clinical setting is scarce. The objective of this study was to evaluate the effect of additional active warming during road or air ambulance transportation of trauma patients.
Patients were assigned to either passive warming with blankets or passive warming with blankets with the addition of an active warming intervention using a large chemical heat pad applied to the upper torso. Ear canal temperature, subjective sensation of cold discomfort and vital signs were monitored.
Mean core temperatures increased from 35.1°C (95% CI; 34.7-35.5°C) to 36.0°C (95% CI; 35.7-36.3°C) (p < 0.05) in patients assigned to passive warming only (n = 22) and from 35.6°C (95% CI; 35.2-36.0°C) to 36.4°C (95% CI; 36.1-36.7°C) (p < 0.05) in patients assigned to additional active warming (n = 26) with no significant differences between the groups. Cold discomfort decreased in 2/3 of patients assigned to passive warming only and in all patients assigned to additional active warming, the difference in cold discomfort change being statistically significant (p < 0.05). Patients assigned to additional active warming also presented a statistically significant decrease in heart rate and respiratory frequency (p < 0.05).
In mildly hypothermic trauma patients, with preserved shivering capacity, adequate passive warming is an effective treatment to establish a slow rewarming rate and to reduce cold discomfort during prehospital transportation. However, the addition of active warming using a chemical heat pad applied to the torso will significantly improve thermal comfort even further and might also reduce the cold induced stress response.
Trial Registration NCT01400152
PMCID: PMC3214151  PMID: 22017799
hypothermia; body temperature regulation; thermal comfort; active warming; passive warming; prehospital trauma care; emergency medical services (EMS)
9.  Unintended Perioperative Hypothermia 
The Ochsner Journal  2011;11(3):259-270.
Hypothermia, defined as a core body temperature less than 36°C (96.8°F), is a relatively common occurrence in the unwarmed surgical patient. A mild degree of perioperative hypothermia can be associated with significant morbidity and mortality. A threefold increase in the frequency of surgical site infections is reported in colorectal surgery patients who experience perioperative hypothermia. As part of the Surgical Care Improvement Project, guidelines aim to decrease the incidence of this complication.
We review the physiology of temperature regulation, mechanisms of hypothermia, effects of anesthetics on thermoregulation, and consequences of hypothermia and summarize recent recommendations for maintaining perioperative normothermia.
Evidence suggests that prewarming for a minimum of 30 minutes may reduce the risk of subsequent hypothermia.
Monitoring of body temperature and avoidance of unintended perioperative hypothermia through active and passive warming measures are the keys to preventing its complications.
PMCID: PMC3179201  PMID: 21960760
Hypothermia; perioperative; prewarming; thermoregulation
10.  Meperidine and skin surface warming additively reduce the shivering threshold: a volunteer study 
Critical Care  2007;11(1):R29.
Mild therapeutic hypothermia has been shown to improve outcome for patients after cardiac arrest and may be beneficial for ischaemic stroke and myocardial ischaemia patients. However, in the awake patient, even a small decrease of core temperature provokes vigorous autonomic reactions–vasoconstriction and shivering–which both inhibit efficient core cooling. Meperidine and skin warming each linearly lower vasoconstriction and shivering thresholds. We tested whether a combination of skin warming and a medium dose of meperidine additively would reduce the shivering threshold to below 34°C without producing significant sedation or respiratory depression.
Eight healthy volunteers participated on four study days: (1) control, (2) skin warming (with forced air and warming mattress), (3) meperidine (target plasma level: 0.9 μg/ml), and (4) skin warming plus meperidine (target plasma level: 0.9 μg/ml). Volunteers were cooled with 4°C cold Ringer lactate infused over a central venous catheter (rate ≈ 2.4°C/hour core temperature drop). Shivering threshold was identified by an increase of oxygen consumption (+20% of baseline). Sedation was assessed with the Observer's Assessment of Alertness/Sedation scale.
Control shivering threshold was 35.5°C ± 0.2°C. Skin warming reduced the shivering threshold to 34.9°C ± 0.5°C (p = 0.01). Meperidine reduced the shivering threshold to 34.2°C ± 0.3°C (p < 0.01). The combination of meperidine and skin warming reduced the shivering threshold to 33.8°C ± 0.2°C (p < 0.01). There were no synergistic or antagonistic effects of meperidine and skin warming (p = 0.59). Only very mild sedation occurred on meperidine days.
A combination of meperidine and skin surface warming reduced the shivering threshold to 33.8°C ± 0.2°C via an additive interaction and produced only very mild sedation and no respiratory toxicity.
PMCID: PMC2151895  PMID: 17316456
11.  The effect of pre-warmed intravenous fluids on prevention of intraoperative hypothermia in cesarean section 
Hypothermia is one of the problems occurring during surgery, which can happen due to thermoregulation mechanism disorders and intake of low temperature IV fluids, and may cause increase in blood pressure, heart rate, intracranial pressure, oxygen consumption, pain, and discomfort to the patient. The rate of cesarean section in our country is three times more than the global standard. As one of the responsibilities of the nurse is patient's advocacy, s/he should support them. This study aimed to investigate the effect of pre-warmed intravenous fluids on prevention of hypothermia during general anesthesia in cesarean section.
Materials and Methods:
Sixty-two women undergoing elective cesarean section by general anesthesia were randomly allocated in two groups of intervention and control. Women in the intervention group received pre-warmed serum (37°C) while those in the control group received serum at room temperature (25.5°C). The core body temperature and some hemodynamic parameters of the participants were assessed during the operation.
The mean of pulse rate, systolic blood pressure, diastolic blood pressure, and arterial O2 saturation in the two groups were not statistically significant (P > 0.05). But the mean of mothers’ core body temperature at the end of anesthesia in the intervention and control groups were 36 ± 0.5°C and 35.34 ± 0.6°C, respectively (P < 0.05).
Infusion of pre-warmed serum (37°C) would prevent intraoperative hypothermia and improve the nursing care for women who undergo cesarean section by general anesthesia.
PMCID: PMC3917187  PMID: 24554962
Cesarean; hypothermia; intravenous fluids; Iran; nursing care
12.  Equipment to prevent, diagnose, and treat hypothermia: a survey of Norwegian pre-hospital services 
Hypothermia is associated with increased morbidity and mortality in trauma patients and poses a challenge in pre-hospital treatment. The aim of this study was to identify equipment to prevent, diagnose, and treat hypothermia in Norwegian pre-hospital services.
In the period of April-August 2011, we conducted a survey of 42 respondents representing a total of 543 pre-hospital units, which included all the national ground ambulance services, the fixed wing and helicopter air ambulance service, and the national search and rescue service. The survey explored available insulation materials, active warming devices, and the presence of protocols describing wrapping methods, temperature monitoring, and the use of warm i.v. fluids.
Throughout the services, hospital duvets, cotton blankets and plastic “bubble-wrap” were the most common insulation materials. Active warming devices were to a small degree available in vehicle ambulances (14%) and the fixed wing ambulance service (44%) but were more common in the helicopter services (58-70%). Suitable thermometers for diagnosing hypothermia were lacking in the vehicle ambulance services (12%). Protocols describing how to insulate patients were present for 73% of vehicle ambulances and 70% of Search and Rescue helicopters. The minority of Helicopter Emergency Medical Services (42%) and Fixed Wing (22%) units was reported to have such protocols.
The most common equipment types to treat and prevent hypothermia in Norwegian pre-hospital services are duvets, plastic “bubble wrap”, and cotton blankets. Active external heating devices and suitable thermometers are not available in most vehicle ambulance units.
PMCID: PMC3751018  PMID: 23938145
13.  Peribulbar anesthesia for cataract surgery: Effect of lidocaine warming and alkalinization on injection pain, motor and sensory nerve blockade 
Indian Journal of Ophthalmology  2010;58(2):105-108.
To compare self-reported pain and efficacy of warmed, alkalinized, and warmed alkalinized lidocaine with plain 2% lidocaine at room temperature for peribulbar anesthesia in cataract surgery.
Materials and Methods:
Through a prospective, single-blinded, randomized, controlled clinical trial 200 patients were divided into four groups. They received either lidocaine at operating room temperature 18°C, control group (Group C), lidocaine warmed to 37°C (Group W), lidocaine alkalinized to a pH of 7.09 ± 0.10 (Group B) or lidocaine at 37°C alkalinized to a pH of 6.94 ± 0.05 (Group WB). All solutions contained Inj. Hyaluronidase 50 IU/ml. Pain was assessed using a 10-cm visual analog score scale. Time of onset of sensory and motor blockade and time to onset of postoperative pain were recorded by a blinded observer.
Mean pain score was significantly lower in Group B and WB compared with Group C (P < 0.001). Onset of analgesia was delayed in Group C compared with Group B (P = 0.021) and WB (P < 0.001). Mean time taken for the onset of complete akinesia and supplementation required for the block was significantly lower in Group B. Time of onset of pain after operation was significantly earlier in Group W compared with Group C (P = 0.036).
Alkalinized lidocaine with or without warming produced less pain than lidocaine injected at room temperature. Alkalinization enhances the effect of warming for sensory nerve blockade, but warming does not enhance alkalinization, in fact it reduces the efficacy of alkalinized solution for blocking the motor nerves in the eye.
PMCID: PMC2854439  PMID: 20195031
Hyaluronidase; lidocaine; peribulbar injection
14.  Perioperative Hypothermia (33°C) Does Not Increase the Occurrence of Cardiovascular Events in Patients Undergoing Cerebral Aneurysm Surgery: Findings from the Intraoperative Hypothermia for Aneurysm Surgery Trial 
Anesthesiology  2010;113(2):327-342.
Perioperative hypothermia has been reported to increase the occurrence of cardiovascular complications. By increasing sympathetic nervous system activity, perioperative hypothermia also has the potential to increase cardiac injury and dysfunction associated with subarachnoid hemorrhage.
The Intraoperative Hypothermia for Aneurysm Surgery Trial randomized patients undergoing cerebral aneurysm surgery to intraoperative hypothermia (n = 499, 33.3 ± 0.8°C) or normothermia (n = 501, 36.7 ± 0.5°C). Cardiovascular events (hypotension, arrhythmias, vasopressor use, myocardial infarction, etc.) were prospectively followed until 3 month follow-up and were compared between hypothermic and normothermic patients. A subset of 62 patients (hypothermia, n = 33; normothermia, n = 29) also had preoperative and postoperative (within 24 h) measurement of cardiac troponin-I and echocardiography to explore the association between perioperative hypothermia and subarachnoid hemorrhage-associated myocardial injury and left ventricular function.
There was no difference between hypothermic and normothermic patients in the occurrence of any single cardiovascular event or in composite cardiovascular events. There was no difference in mortality (6%) between groups and there was only a single primary cardiovascular death (normothermia). There was no difference between hypothermic and normothermic patients in post- vs. preoperative left ventricular regional wall motion or ejection fraction. Compared with preoperative values, hypothermic patients had no postoperative increase in cardiac troponin-I (median change 0.00 μg/L) whereas normothermic patients had a small postoperative increase (median change + 0.01 μg/L, P = 0.038).
In patients undergoing cerebral aneurysm surgery, perioperative hypothermia was not associated with an increased occurrence of cardiovascular events.
PMCID: PMC2910193  PMID: 20571361
15.  Methods of Patient Warming during Abdominal Surgery 
PLoS ONE  2012;7(7):e39622.
Keeping abdominal surgery patients warm is common and warming methods are needed in power outages during natural disasters. We aimed to evaluate the efficacy of low-cost, low-power warming methods for maintaining normothermia in abdominal surgery patients.
Patients (n = 160) scheduled for elective abdominal surgery were included in this prospective clinical study. Five warming methods were applied: heated blood transfusion/fluid infusion vs. unheated; wrapping patients vs. not wrapping; applying moist dressings, heated or not; surgical field rinse heated or not; and applying heating blankets or not. Patients’ nasopharyngeal and rectal temperatures were recorded to evaluate warming efficacy. Significant differences were found in mean temperatures of warmed patients compared to those not warmed.
When we compared temperatures of abdominal surgery patient groups receiving three specific warming methods with temperatures of control groups not receiving these methods, significant differences were revealed in temperatures maintained during the surgeries between the warmed groups and controls.
The value of maintaining normothermia in patients undergoing abdominal surgery under general anesthesia is accepted. Three effective economical and practically applicable warming methods are combined body wrapping and heating blanket; combined body wrapping, heated moist dressings, and heating blanket; combined body wrapping, heated moist dressings, and warmed surgical rinse fluid, with or without heating blanket. These methods are practically applicable when low-cost method is indeed needed.
PMCID: PMC3394771  PMID: 22808045
16.  Core temperatures during major abdominal surgery in patients warmed with new circulating-water garment, forced-air warming, or carbon-fiber resistive-heating system 
Journal of Anesthesia  2011;26(2):168-173.
It has been reported that recently developed circulating-water garments transfer more heat than a forced-air warming system. The authors evaluated the hypothesis that circulating-water leg wraps combined with a water mattress better maintain intraoperative core temperature ≥36°C than either forced-air warming or carbon-fiber resistive heating during major abdominal surgery.
Thirty-six patients undergoing open abdominal surgery were randomly assigned to warming with: (1) circulating-water leg wraps combined with a full-length circulating-water mattress set at 42°C, (2) a lower-body forced-air cover set on high (≈43°C), and (3) a carbon-fiber resistive-heating cover set at 42°C. Patients were anesthetized with general anesthesia combined with continuous epidural analgesia. The primary outcome was intraoperative tympanic-membrane temperature ≥36°C.
In the 2 h after anesthesia induction, core temperature decreased 1.0 ± 0.5°C in the forced-air group, 0.9 ± 0.2°C in the carbon-fiber group, and 0.4 ± 0.4°C in the circulating-water leg wraps and mattress group (P < 0.05 vs. forced-air and carbon-fiber heating). At the end of surgery, core temperature was 0.2 ± 0.7°C above preoperative values in the circulating-water group but remained 0.6 ± 0.9°C less in the forced-air and 0.6 ± 0.4°C less in the carbon-fiber groups (P < 0.05 vs. carbon fiber).
The combination of circulating-water leg wraps and a mattress better maintain intraoperative core temperature than did forced-air and carbon-fiber warming systems.
PMCID: PMC3328673  PMID: 22189652
Temperature; Hypothermia; Circulating-water garment; Carbon fiber; Forced air
17.  Warm-blood cardioplegia with low or high magnesium for coronary bypass surgery: a randomised controlled trial☆ 
Objective: Magnesium (Mg2+) is cardioprotective and has been routinely used to supplement cardioplegic solutions during coronary artery bypass graft (CABG) surgery. However, there is no consensus about the Mg2+ concentration that should be used. The aim of this study was to compare the effects of intermittent antegrade warm-blood cardioplegia supplemented with either low- or high-concentration Mg2+. Methods: This study was a randomised controlled trial carried out in two cardiac surgery centres, Bristol, UK and Cuneo, Italy. Patients undergoing isolated CABG with cardiopulmonary bypass were eligible. Patients were randomised to receive warm-blood cardioplegia supplemented with 5 or 16 mmol l−1 Mg2+. The primary outcome was postoperative atrial fibrillation. Secondary outcomes were serum biochemical markers (troponin I, Mg2+, potassium, lactate and creatinine) and time-to-plegia arrest. Intra-operative and postoperative clinical outcomes were also recorded. Results: Data from two centres for 691 patients (342 low and 349 high Mg2+) were analysed. Baseline characteristics were similar for both groups. There was no significant difference in the frequency of postoperative atrial fibrillation in the high (32.8%) and low (32.0%) groups (risk ratio 1.03, 95% confidence interval, CI, 0.82–1.28). However, compared with the low group, troponin I release was 28% less (95% CI 55–94%, p = 0.02) in the high-Mg2+ group. The 30-day mortality was 0.72% (n = 5); all deaths occurred in the high-Mg2+ group but there was no significant difference between the groups (p = 0.06). Frequencies of other major complications were similar in the two groups. Conclusions: Warm-blood cardioplegia supplemented with 16 mmol l−1 Mg2+, compared with 5 mmol l−1 Mg2+, does not reduce the frequency of postoperative atrial fibrillation in patients undergoing CABG but may reduce cardiac injury. (This trial was registered as ISRCTN95530505.)
PMCID: PMC3162136  PMID: 21353585
Myocardial protection; Cardioplegia; CABG; Surgery; Atrial fibrillation; Flutter
18.  European society of intensive care medicine study of therapeutic hypothermia (32-35°C) for intracranial pressure reduction after traumatic brain injury (the Eurotherm3235Trial) 
Trials  2011;12:8.
Traumatic brain injury is a major cause of death and severe disability worldwide with 1,000,000 hospital admissions per annum throughout the European Union.
Therapeutic hypothermia to reduce intracranial hypertension may improve patient outcome but key issues are length of hypothermia treatment and speed of re-warming. A recent meta-analysis showed improved outcome when hypothermia was continued for between 48 hours and 5 days and patients were re-warmed slowly (1°C/4 hours). Previous experience with cooling also appears to be important if complications, which may outweigh the benefits of hypothermia, are to be avoided.
This is a pragmatic, multi-centre randomised controlled trial examining the effects of hypothermia 32-35°C, titrated to reduce intracranial pressure <20 mmHg, on morbidity and mortality 6 months after traumatic brain injury. The study aims to recruit 1800 patients over 41 months. Enrolment started in April 2010.
Participants are randomised to either standard care or standard care with titrated therapeutic hypothermia. Hypothermia is initiated with 20-30 ml/kg of intravenous, refrigerated 0.9% saline and maintained using each centre's usual cooling technique. There is a guideline for detection and treatment of shivering in the intervention group. Hypothermia is maintained for at least 48 hours in the treatment group and continued for as long as is necessary to maintain intracranial pressure <20 mmHg. Intracranial hypertension is defined as an intracranial pressure >20 mmHg in accordance with the Brain Trauma Foundation Guidelines, 2007.
The Eurotherm3235Trial is the most important clinical trial in critical care ever conceived by European intensive care medicine, because it was launched and funded by the European Society of Intensive Care Medicine and will be the largest non-commercial randomised controlled trial due to the substantial number of centres required to deliver the target number of patients. It represents a new and fundamental step for intensive care medicine in Europe. Recruitment will continue until January 2013 and interested clinicians from intensive care units worldwide can still join this important collaboration by contacting the Trial Coordinating Team via the trial website
Trial registration
Current Controlled Trials ISRCTN34555414
PMCID: PMC3027122  PMID: 21226939
19.  The Influence of Hypothermia on Transfusion Requirement in Patients Who Received Clopidogrel in Proximity to Off-Pump Coronary Bypass Surgery 
Yonsei Medical Journal  2013;55(1):224-231.
Hypothermia adversely affects the coagulation that could be of clinical significance in patients receiving clopidogrel. We evaluated the influence of hypothermia on transfusion requirements in patients undergoing isolated off-pump coronary artery bypass surgery (OPCAB) who continued clopidogrel use within 5 days of surgery.
Materials and Methods
Protocol-based, prospectively entered data of 369 patients were retrospectively reviewed. The time-weighted average of intraoperative temperatures and the temperature upon ICU admission (TWA-temp) was assessed. Patients were divided into normothermia (≥36℃, n=224) and hypothermia (<36℃, n=145) group. The transfusion requirement for perioperative blood loss was assessed and compared.
Patients with hypothermia were older and had lower body surface area (BSA) than patients with normothermia. Age and BSA adjusted transfusion requirement was significantly larger in the hypothermia group [patients requiring transfusion: 64% versus 48%, p=0.003; number of units: 0 (0-2) units versus 2 (0-3) units, p=0.002]. In multivariate analysis of predictors of perioperative multiple transfusion requirements, hypothermia was identified as an independent risk factor along with age, female gender, BSA, chronic kidney disease, and congestive heart failure.
Hypothermia was associated with increased transfusion requirement in patients undergoing OPCAB who received clopidogrel in proximity to surgery. Considering the high prevalence and the possibility of hypothermia being a modifiable risk factor, aggressive measures should be undertaken to maintain normothermia in those patients.
PMCID: PMC3874931  PMID: 24339311
Clopidogrel; hypothermia; off-pump coronary artery bypass surgery; transfusion
20.  Intraocular adrenaline maintains mydriasis during cataract surgery. 
Cataract surgery is performed more easily if mydriasis can be maintained until the intraocular lens has been inserted. Intraocular irrigation with adrenaline is thought to be of benefit in this respect, and is used by some surgeons but not others. This prospective double blind controlled trial assessed the efficacy and safety of using perioperative adrenaline during extracapsular cataract surgery, as an adjunct to preoperative topical mydriatics. Seventy patients were randomised to receive intraocular irrigation fluid with or without 1:1,000,000 adrenaline. The adrenaline entering the eye through the anterior capsulotomy needle helped to resist the miosis induced by expression of the nucleus (7.1 versus 6.5 mm). The mydriasis maintained during irrigation aspiration was significantly greater in the group receiving adrenaline (6.6 versus 6.0 mm, p < 0.02). Their pupil diameters were also significantly larger at 20 minutes (p < 0.001) and 30 minutes (p < 0.01) into surgery. Pupillary constriction to a diameter of less than 5 mm occurred more frequently in the group not receiving adrenaline. Pulse rate and blood pressure in the 27 patients who had local anaesthesia showed no significant difference between the treatment groups (p > 0.05), and there was no significant variation from baseline (p > 0.05). Intraocular irrigation with adrenaline 1:1,000,000 is a safe and effective means of maintaining mydriasis during cataract surgery.
PMCID: PMC504708  PMID: 8123633
21.  Treatment of first episodes of acute anal fissure: prospective randomised study of lignocaine ointment versus hydrocortisone ointment or warm sitz baths plus bran. 
One hundred and three patients with an acute first episode of posterior anal fissure were randomised to receive a three week trial of lignocaine ointment (n = 33) versus hydrocortisone ointment (n = 35) or warm sitz baths combined with an intake of unprocessed bran (n =35). Seven patients were withdrawn owing to failure to adhere to the trial protocol. After one and two weeks of treatment symptomatic relief was significantly better among patients treated with sitz baths and bran than among patients treated with lignocaine ointment or hydrocortisone ointment. After three weeks there was no difference in symptomatic relief among the three groups. Patients treated with lignocaine, however, had significantly fewer healed fissures (60%) than patients treated with hydrocortisone (82.4%) or warm sitz baths and bran (87%). In this study warm sitz baths plus an intake of unprocessed bran came out as the treatment of choice for an acute first episode of posterior anal fissure. This treatment is cheap, has no potential serious side effects, and brings the best and quickest relief of symptoms.
PMCID: PMC1340178  PMID: 3011180
22.  The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects 
Warm-up and stretching are suggested to increase hamstring flexibility and reduce the risk of injury. This study examined the short-term effects of warm-up, static stretching and dynamic stretching on hamstring flexibility in individuals with previous hamstring injury and uninjured controls.
A randomised crossover study design, over 2 separate days. Hamstring flexibility was assessed using passive knee extension range of motion (PKE ROM). 18 previously injured individuals and 18 uninjured controls participated. On both days, four measurements of PKE ROM were recorded: (1) at baseline; (2) after warm-up; (3) after stretch (static or dynamic) and (4) after a 15-minute rest. Participants carried out both static and dynamic stretches, but on different days. Data were analysed using Anova.
Across both groups, there was a significant main effect for time (p < 0.001). PKE ROM significantly increased with warm-up (p < 0.001). From warm-up, PKE ROM further increased with static stretching (p = 0.04) but significantly decreased after dynamic stretching (p = 0.013). The increased flexibility after warm-up and static stretching reduced significantly (p < 0.001) after 15 minutes of rest, but remained significantly greater than at baseline (p < 0.001). Between groups, there was no main effect for group (p = 0.462), with no difference in mean PKE ROM values at any individual stage of the protocol (p > 0.05). Using ANCOVA to adjust for the non-significant (p = 0.141) baseline difference between groups, the previously injured group demonstrated a greater response to warm-up and static stretching, however this was not statistically significant (p = 0.05).
Warm-up significantly increased hamstring flexibility. Static stretching also increased hamstring flexibility, whereas dynamic did not, in agreement with previous findings on uninjured controls. The effect of warm-up and static stretching on flexibility was greater in those with reduced flexibility post-injury, but this did not reach statistical significance. Further prospective research is required to validate the hypothesis that increased flexibility improves outcomes.
Trial Registration
PMCID: PMC2679703  PMID: 19371432
23.  Reduction of oxidative stress does not affect recovery of myocardial function: warm continuous versus cold intermittent blood cardioplegia. 
Heart  1997;77(5):465-473.
OBJECTIVE: To compare oxidative stress after cardiac surgery in patients treated with two different methods of myocardial protection: warm continuous versus cold intermittent blood cardioplegia. To correlate oxidative stress with postoperative myocardial dysfunction. DESIGN: Prospective, randomised, double blind, trial. SETTING: Institutional centre of cardiovascular surgery. PATIENTS: 20 patients were selected for coronary artery bypass surgery (CABG) on the following basis: stable angina, ejection fraction > 50%, double or triple vessel disease, no previous CABG or associated disease. Patients were randomised to two groups of 10 patients each. INTERVENTIONS: Patients underwent CABG with one of two different methods of myocardial protection and cardiopulmonary bypass. CBC group: intermittent cold blood antegrade-retrograde cardioplegia with moderate hypothermic cardiopulmonary bypass; WBC group: continuous warm blood antegrade-retrograde cardioplegia with mild hypothermic cardiopulmonary bypass. MAIN OUTCOME MEASURE: The index of oxidative stress used was the alteration of whole blood and plasma glutathione redox status. Samples were collected from the coronary sinus and peripheral vein before anaesthesia (T1), before aortic unclamping (T2), 15 minutes (T3), and 30 minutes (T4) after unclamping. Haemodynamic parameters were measured with thermodilution techniques. RESULTS: Oxidised glutathione and glutathione-cysteine mixed disulphide significantly increased in the coronary sinus plasma in the CBC group, and the overall redox balance of glutathione was decreased (P < 0.01) at T2-T4 versus T1, and compared with the WBC group. Comparable results were obtained for coronary sinus blood. There was no correlation between postoperative haemodynamic measurements and oxidative stress markers. CONCLUSIONS: Oxidative stress was significant in patients undergoing CABG using cold blood cardioplegia, while the warm technique minimised the effects of ischaemia. However, oxidative stress was not correlated with myocardial dysfunction following CABG.
PMCID: PMC484771  PMID: 9196419
24.  Capillary blood sampling: should the heel be warmed? 
The hypothesis that capillary blood sampling is made easier by warming the heel was examined in a randomised, controlled trial of healthy newborn infants. Sampling was performed using an automated lancet with or without prior warming. The time taken to collect a standard volume of blood, the number of repeat procedures needed, and the infants' behavioural responses were measured. Eighty one procedures were studied in 57 infants. Warming produced a median rise in heel skin temperature of 4.7 degrees C. However, there were no significant differences between the warmed and unwarmed groups in any of the outcome measures. Heel skin temperature is not an important factor in capillary blood sampling. Attention should be directed towards improving sampling devices and technique.
PMCID: PMC2528534  PMID: 8777665
25.  Caloric stimulation with near infrared radiation does not induce paradoxical nystagmus 
Near infrared radiation can be used for warm stimulation in caloric irrigation of the equilibrium organ. Aim of this study was to determine whether near infrared radiation offers effective stimulation of the vestibular organ, whether it is well tolerated by the patients and especially whether it is a viable alternative to warm air stimulation in patients with defects of the tympanic membrane and radical mastoid cavities. Patients with perforations of the tympanic membrane (n = 15) and with radical mastoid cavities (n = 13) were tested both with near infrared radiation and warm dry air. A caloric-induced nystagmus could be seen equally effectively and rapidly in all patients. Contrary to stimulation with warm dry air, no paradoxical nystagmus was observed following caloric irrigation with a warm stimulus (near infrared radiation). Results of a questionnaire showed excellent patient acceptance of near infrared stimulation with no arousal effects or unpleasant feeling. In conclusion, near infrared radiation proved to be an alternative method of caloric irrigation to warm dry air in patients with tympanic membrane defects and radical mastoid cavities. Near infrared radiation is pleasant, quick, contact free, sterile and quiet. With this method an effective caloric warm stimulus is available. If near infrared radiation is used for caloric stimulus no evaporative heat loss occurs.
PMCID: PMC3203743  PMID: 22058588
Vertigo; Semicircular canals; Near infrared radiation; Caloric stimulation; Radical cavity

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