Tympanic Membrane Temperature Research Articles

A study of the efficacy of stellate ganglion blocks in complex regional pain syndromes of the upper body.

Background and Aims:The effect of stellate ganglion blocks (SGBs) was examined in complex regional pain syndromes (CRPS) of the upper body.Material and Methods:A total of 287 SGB were given to patients with documented CRPS on medications. Spontaneous and provoked pain assessment was done with numeric pain rating scale (NPRS). The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire and range of motion (ROM) was recorded before and after each blockade. Difference between a 15-point “global rating of change” scale determined the minimal clinically important difference of the DASH score.Results:The overall mean pain reduction was 73.2% (r = 0.83, P < 0.001) considering spontaneous and 55.8% (r = 0.77, P < 0.001) on provoked pain. Mean DASH score decreased from 53 (range 36–63; P = 0.14) to 10.4 (range 10–49.2; P = 0.005). The sensitivity to change was 6.9 for spontaneous and 4.9 for provoked pain. Increase in ipsilateral limb temperature has a good correlation with Horner's syndrome (HS) and sympathetic blockade. Minor, self-limiting complications, such as hoarseness, dysphagia, local hematoma, and ipsilateral brachial plexus block occurred in 11.5%. A rare complication of contralateral HS was documented. One patient developed a small pneumothorax, but it did not require intervention.Conclusions:SGB are relatively safe and effective management in patients with neuropathic conditions already on pharmacotherapy. Serial blocks attained an average reduction in pain by >3 NPRS points from the baseline for both spontaneous and provoked pain with a decrease in mean DASH score and improvement in ROM.

Abstract PR610

Background & Objectives: Anaesthesia alters normal body thermoregulation control leading to perioperative hypothermia. Monitoring intra-operative body temperature is frequently reinforced and can be achieved with various methods. We performed a correlation study between infrared tympanic membrane temperature (TMT) and nasopharyngeal temperature (NT) to the core oesophageal temperature (OT). Materials & Methods: Seventy seven patients aged 18 to 60 years requiring general anaesthesia with endotracheal intubation was recruited. A set of three temperatures (TMT, NT and OT) were taken after induction, at one hour and at the second hour intraoperatively on each patient. Bland-Altman plots were utilized to assess agreement of temperatures, with the OT taken as the reference or gold standard method. Results: The mean TMT, NT and OT were 36.84 ± 0.45 °C, 36.24 ± 0.50 °C and 36.20 ± 0.48 °C respectively. The correlation (r) between TMT with OT was 0.819 (p<0.0001), NT with OT was 0.911 (p<0.0001) and NT with TMT was 0.773 (p<0.0001). The mean difference (bias) between NT and OT was found to be -0.064° C with 95% limits of agreement (LOA) of -0.467 to 0.34° C and SD ± 0.40. The mean difference between TMT and OT was found to be -0.023° C with 95% LOA of -0.577 to 0.531° C and SD ± 0.55. The agreement between TMT and OT was outside the acceptable limits of ± 0.5° C via a Bland-Altman plot. The agreement between NT and OT was within acceptable limits at ± 0.40° C. Conclusion: NT showed a higher correlation with OT, although both NT and TMT had strong positive correlations with OT measurement. NT measurement also accurately reflects the lower OT. Our study supports the use of NT monitoring as a simpler and less invasive method to measure the core body temperature.

Abstract PR469

Background & Objectives: Meperidine is accepted as the gold standard in the treatment of postoperative shivering which is often seen following anesthesia1,2. The aim of this study is to investigate the effects of meperidine, ketamine and tramadol on the prevention of postanesthesia shivering (PAS), their analgesic efficiency and postoperative sedation levels. Materials & Methods: Ninety patients were included in this randomised prospective double blind study. During the closure of the surgical wound, the patients in Group M (n=30) were given meperidine 0.3 mg/kg, the patients in Group K (n=30) were given ketamine 0.25 mg/kg and the patients in Group T (n=30) were given tramadol 1mg/kg intravenously. Heart rate (HR), mean arterial pressure (MAP), peripheral oxygen saturation (SpO2), tympanic membrane temperatures (TMT), shivering, modified observer’s assessment of alertness/sedation scale and visual analogue scale (VAS) pain scores were recorded in the postoperative period. Results: Demographic data, durations of surgery, anesthesia and extubation, HR, MAP, SpO2, TMT, VAS pain scores and side effects were similar between groups. Although the number of patients according to shivering scores were similar between groups, the incidence of shivering at the postoperative 0th minute was lower in the tramadol group compared to other two goups and similar between meperidine and ketamine groups (p=0.040). Sedation scores in Group T were higher than Group K at the 10th minute and higher than Group K and Group M at the 20th minute (p<0.05). Meperidine requirements for analgesia was lower in Group T (p=0.035). Meperidine requirements for the treatment of PAS were similar between three groups (p=0.233). There was no difference concerning the metoclopramide requirement for the treatment of postoperative nausea and vomiting between groups (p=0.344).Conclusion: The findings of similar TMT and VAS pain scores but different PAS incidences point out to the pharmacological and physiological properties of the prophylactic agents that are used more than the hypothermia-related thermoregulatory mechanisms and pain-related nonthermoregulatory mechanisms. Therefore, tramadol can be chosen as an alternative agent for the prophylactic treatment of PAS and pain.

Temperature measurement in the adult emergency department: oral, tympanic membrane and temporal artery temperatures versus rectal temperature

ObjectiveThe objective was to compare agreement between three non-invasive measures of temperature and rectal temperatures and to estimate the sensitivity and specificity of these measures to detect a rectal temperature...

Intraventricular temperature measured by diffusion-weighted imaging compared with brain parenchymal temperature measured by MRSin vivo

We examined and compared the temperatures of the intraventricular cerebrospinal fluid (Tv ) and the brain parenchyma (Tp ) using MRI, with reference to the tympanic membrane temperature (Tt ) in healthy subjects. We estimated Tv and Tp values from data gathered simultaneously by MR diffusion-weighted imaging (DWI) and MRS, respectively, in 35 healthy volunteers (17 males, 18 females; age 25-78 years). We also obtained Tt values just before each MR examination to evaluate the relationships among the three temperatures. There were significant positive correlations between Tv and Tp (R = 0.611, p <0.001). The correlation was also significant after correction for Tt (R = 0.642, p <0.001). There was no significant correlation between Tv and Tt or between Tp and Tt in the men or the women. Negative correlations were found between Tv and age and between Tp and age in the males but not females. DWI thermometry seems to reflect the intracranial environment as accurately as MRS thermometry. An age-dependent decline in temperature was evident in our male subjects by both DWI and MRS thermometry, probably due to the decrease in cerebral metabolism with age. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of wearing an N95 filtering facepiece respirator on superomedial orbital infrared indirect brain temperature measurements.

To determine any effect of wearing a filtering facepiece respirator on brain temperature. Subjects (n=18) wore a filtering facepiece respirator (FFR) for 1h at rest while undergoing infrared thermography measurements of the superomedial periobital region of the eye, a non-invasive indirect method of brain temperature measurements we termed the superomedial orbital infrared indirect brain temperature (SOIIBT) measurement. Temperature of the facial skin covered by the FFR, infrared temperature measurements of the tympanic membrane and superficial temporal artery region were concurrently measured, and subjective impressions of thermal comfort obtained simultaneously. The temperature of the skin under the FFR and subjective impressions of thermal discomfort both increased significantly. The mean tympanic membrane temperature did not increase, and the superficial temporal artery region temperature decreased significantly. The SOIIBT values did not change significantly, but subjects who switched from nasal to oronasal breathing during the study (n=5) experienced a slight increase in the SOIIBT measurements. Wearing a FFR for 1h at rest does not have a significant effect on brain temperatures, as evaluated by the SOIIBT measurements, but a change in the route of breathing may impact these measurements. These findings suggest that subjective impressions of thermal discomfort from wearing a FFR under the study conditions are more likely the result of local dermal sensations rather than brain warming.

Comparative efficacy of intravenous dexmedetomidine, clonidine, and tramadol in postanesthesia shivering.

Background and Aims:Postanesthesia shivering continues to be a major challenge in the perioperative care. We compared the efficacy of tramadol, clonidine, and dexmedetomidine in preventing postoperative shivering and its potential adverse effects in patients undergoing laparoscopic cholecystectomy under general anesthesia.Material and Methods:One hundred and twenty American Society of Anesthesiologists I and II patients scheduled for elective laparoscopic cholecystectomy under general anesthesia were divided into four equal groups. Group 1 received clonidine 2 μg/kg, Group 2 received tramadol 1 mg/kg, Group 3 received dexmedetomidine 1 mcg/kg all intravenous diluted in NS to 5 ml, and Group 4 received NS intravenous 5 ml. Parameters analysed included postoperative blood pressure (BP), pulse rate, respiratory rate (RR), arterial saturation, and tympanic membrane temperature. Patients were observed for shivering episodes, sedation, pain, respiratory depression, nausea, and vomiting. Analysis of variance, Tukey's post-hoc comparison, Chi-square test and Bonferroni post-hoc comparison test were performed using SPSS (Statistical analysis by Statistical Package of Social Sciences of Microsoft Windows) Statistics (version 16.0).Results:The incidence of shivering was 10, 3.3, 13.3 and 40% in Groups 1, 2, 3, and 4 respectively. Patients who were given tramadol had significantly less shivering than patients in clonidine and dexmedetomidine groups (P < 0.01).Conclusion:All the three drugs were effective in preventing postoperative shivering. However, tramadol has been found to be more efficacious in preventing postoperative shivering.

Prophylactic intravenous paracetamol for prevention of shivering after general anesthesia in elective cesarean section

Background: Postoperative shivering is an important common complication after general anesthesia. This may lead to dissatisfaction and a sense of discomfort, especially in parturients undergoing cesarean section. In addition to warming, many drugs have been investigated for prevention of shivering. The aim of this study was to evaluate the efficacy of intravenous paracetamol for prevention of shivering after general anesthesia in cesarean section. Materials and Methods: In this prospective randomized double-blind controlled clinical trial, 110 pregnant women, physical Status I or II, based on the classification of American Society of Anesthesiologists (ASA), aged 18–40 years, who were scheduled for elective cesarean section under general anesthesia were included in the study. They were randomly divided into two groups of 55 each. One group received 100 ml normal saline, and another group received 1 g of paracetamol in 100 ml normal saline intravenously, 15 min after the delivery of the baby. The anesthesia technique was similar in both the groups. Tympanic membrane temperature was measured before and after the induction of anesthesia and every 15 min till the end of recovery from anesthesia. Postanesthetic shivering was graded on a scale of 0 to 4; if the score was more than 2, it was treated with 25 mg pethedine. Vital signs and side effects were recorded during the surgery and recovery period. Results: There were no significant differences between the two groups regarding age, weight, height, and duration of surgery (P > 0.05). Shivering was seen in 5 parturients (9.1%) in paracetamol group (group A) and 28 parturients (50.9%) in the saline group (group N). On a scale of 0 to 4, shivering was of lower intensity in paracetamol group compared to the saline group (P 0.05). There was no difference in the incidence of hypotension, nausea, and vomiting among the two groups (P > 0.05). Conclusion: The prophylactic use of intravenous paracetamol during surgery is effective for the prevention of postoperative shivering.

A Reappraisal of the Minimum Duration of Antibiotic Treatment Before Approval of Return to School for Children With Streptococcal Pharyngitis.

To determine whether a single dose of amoxicillin administered to a symptomatic child with confirmed strep throat might allow the child to return to school as little as 12 hours later. We enrolled 111 evaluable children with sore throat plus a positive streptococcal rapid antigen detection test (RADT) as well as a positive result for group A Streptococci (GAS). After throat swab specimens were obtained, all participants received a single dose of amoxicillin (50 mg/kg). Twelve to 23 hours after the first dose of amoxicillin, all participants returned in the morning of day 2 for a second throat swab specimen. At the day 2 visit, a nurse or medical assistant obtained an interval history, tympanic membrane temperature, and a pediatrician or nurse practitioner examined the oropharynx. On the morning of day 2, only 10 of 111 participants continued to have a positive RADT result, confirmed by overnight throat culture. GAS were not detectable on the day 2 throat specimen by RADT and also by culture in 91% of the study participants (confidence interval: 86-96%). Seven of 10 failures had a marked decrease in number of β-hemolytic colonies, which were 3+ to 4+ on the initial overnight culture plate and decreased to 1+ on the follow-up (obtained on day 2) throat culture plate. Two participants continued to have 3+ or 4+ GAS after incubation of the second throat culture specimen. Even in the late afternoon, a full dose of amoxicillin (50 mg/kg) administered after notification of positive RADT results for GAS resulted in nondetection of GAS in 91% of children the next morning. All children treated with amoxicillin for "strep throat" by 5 PM of day 1 may, if afebrile and improved, attend school on day 2.

Comparison of oesophageal, rectal and tympanic membrane temperature in anaesthetised client-owned cats

Objectives: To determine the agreement between a veterinary-specific tympanic membrane thermometer and measurement of core oesophageal and rectal temperature in client-owned anaesthetised cats. Methods: A prospective study was performed using 20 cats that were scheduled to undergo general anaesthesia. For each cat, five consecutive temperature recordings were taken from an oesophageal temperature probe (OT), rectal thermometer (RT) and a veterinary-specific tympanic membrane thermometer (TT) prior to surgery. The temperatures were compared using Bland-Altman analysis. Results: Mean differences for the TT compared with OT and RT were -0.86°C (SD = 0.62°C, 95% CI [-2.39°C, 0.67°C]) and -0.93°C (SD = 0.57°C, 95% CI [-2.27, 0.44]) respectively; both greater than the accepted maximal clinical tolerance of 0.20°C. The mean difference for the RT compared with the OT was 0.06°C (SD = 0.28°C, 95% CI [-0.56, 0.67]). Clinical significance: The TT does not accurately represent core body temperature in cats under general anaesthesia and should not be used interchangeably with oesophageal thermometers. Rectal temperatures can be used to reliably approximate core temperature in anaesthetised cats.

Lateralized differences in tympanic membrane temperature, but not induced mood, are related to episodic memory

The present research examined the effects of pre-encoding and pre-recall induced mood on episodic memory. It was hypothesized that happy and/or angry mood prior to encoding (increasing left hemisphere activity), in tandem with fearful mood prior to recall (increasing right hemisphere activity) would be associated with superior episodic memory. It was also hypothesized that tympanic membrane measures (TMT), indicative of hemispheric activity, would change as a function of induced mood. Although subjectively-experienced mood induction was successful, pre-encoding and pre-recall mood did not alter memory, and only altered TMT in the pre-encoding fear and pre-recall angry mood induction conditions. Interestingly, baseline absolute difference between left and right TMT, a measure of differential hemispheric activity, regardless of the direction of that activity, was significantly positively related to number of total words written, number of correctly recalled words, and corrected recall score. This same TMT measure pre-encoding, regardless of specific mood, was significantly negatively related to false recall. Results are discussed in terms the HERA model of episodic memory, and in the nature of interhemispheric interaction involved in episodic recall.

Effect of wearing an N95 respirator on infrared tympanic membrane temperature measurements.

To determine the impact of wearing an N95 filtering facepiece respirator (N95 FFR) on tympanic temperature measurements. TMT measurements, with and without wearing an N95 filtering facepiece respirator (N95 FFR) were obtained at the onset and termination of 1h of treadmill exercise in 21 subjects, and at staggered time intervals (0, 20, 40, 60min) during combined sedentary activity and exercise of another 46 subjects, to determine any effect on TMT. A total of 877 TMT measurements were obtained that demonstrated a mean TMT increase of 0.05°C in the first study group (p=0.04) and a 0.19°C decrease in the second study group (p<0.001) with the wearing of an N95 FFR, both of which were lower than controls. Wearing an N95 FFR for 1h, at different levels of activity, results in significantly lower TMT values than not wearing an N95 FFR, but the magnitude of the changes would likely have minimal clinical significance.

Tympanic membrane temperature in adopted children associated with sleep problems and pre-adoption living arrangements: an exploratory study.

BackgroundTympanic membrane temperature (TMT) has been proposed as an indicator of cerebral activation and TMT asymmetry may indicate lateralization, which has been associated with specific (problem) behaviors in children and adults. The current study explored the relations between pre-adoption living arrangements, TMT, and behavior and sleep problems in a sample of adopted toddlers.MethodsNinety-two families who had adopted a Chinese girl who had previously been placed in an institution or foster care reported on behavior problems using the Child Behavior Checklist and TMT two months (Time 1) and six months (Time 2) after adoption.ResultsStructural equation modeling revealed that institutionalized children had significantly higher left than right TMTs compared with foster care children at Time 2. A higher left than right TMT was associated with increased sleep problems and total behavior problems at Time 1, but not at Time 2.ConclusionsOur findings with regard to pre-adoption living arrangements, TMT asymmetry, and sleep problems suggest that TMT is sensitive to early environmental influences and may be a biological marker of vulnerability to the development of sleep problems in children from adverse backgrounds.

Effect of intraoperative amino acids with or without glucose infusion on body temperature, insulin, and blood glucose levels in patients undergoing laparoscopic colectomy: A preliminary report

ObjectiveAmino acid administration helps to prevent intraoperative hypothermia but may enhance thermogenesis when combined with glucose infusion. The aim of this study was to examine the effect of intraoperative amino acid administration, with or without glucose infusion, on temperature regulation during laparoscopic colectomy. MethodsTwenty-one patients whose physical status was classified I or II by the American Society of Anesthesiologists, and who were undergoing elective laparoscopic colectomy were enrolled. The exclusion criteria were a history of diabetes and/or obesity, preoperative high levels of C-reactive protein, high blood glucose and/or body temperature after anesthesia induction, and surgical time >500 minutes. Each patient received an acetate ringer solution and was randomly assigned to one of three groups. Group A patients were given only amino acids. Group AG patients were given amino acids and glucose. Group C patients were given neither amino acids nor glucose. Tympanic membrane temperatures and blood glucose and insulin levels were measured intraoperatively. ResultsIntraoperative amino acid infusion significantly increased body temperature during surgery as compared with either Group AG or C. The blood glucose levels in Group AG were significantly higher than those in Groups A and C. However, there were no significant differences between Groups A and C. Two hours after anesthesia induction, serum insulin levels in Groups A and AG significantly increased compared with Group C. No significant differences in the postoperative complications or patient hospitalization lengths were detected between the groups. ConclusionIntraoperative amino acid infusion without glucose administration maintains body temperature more effectively than combined amino acid and glucose infusion in patients undergoing laparoscopic colectomy, despite unaltered intraoperative insulin levels.

Risk factors for acute kidney injury in aortic arch surgery with selective cerebral perfusion and mild hypothermic lower body circulatory arrest.

Previous studies have reported a high incidence of acute kidney injury (AKI) after thoracic aortic surgery. However, the incidence of AKI in patients undergoing total arch replacement (TAR) with selective cerebral perfusion (SCP) and mild hypothermic lower body circulatory arrest (mild HLBCA) with a tympanic temperature of 25°C remains unknown. We studied AKI incidence and associated risk factors, as defined by the Acute Kidney Injury Network (AKIN). We examined 116 consecutive patients with aortic arch aneurysm undergoing non-emergency TAR. Our surgical method is standardized to use systemic cooling of the tympanic membrane temperature to 25°C for circulatory arrest, followed by SCP and myocardial protection by cold blood cardioplegia. Anastomoses were sequentially constructed at the distal arch, the proximal root, the left sub-clavian artery, the left carotid artery and the right brachiocephalic artery. Bladder temperature was generally around 30°C at the start of lower body circulatory arrest (mild HLBCA) until reperfusion of the distal aorta. The incidence of AKI was investigated, with multivariate analysis of its risk factors. The mean operation time, cardiopulmonary bypass (CPB) time, mild HLBCA time and SCP time were 270.6 ± 72.5, 151.0 ± 46.4, 53.1 ± 20.1 and 99.0 ± 28.4 min, respectively. Hospital mortality occurred in 2 cases (1.7%). AKI occurred in 50 cases (43.1%); of which, 2 cases required renal replacement therapy (RRT). However, AKI had subsided in 44 cases by discharge. For contemporary perspective, the incidence of AKI was 32.8% in off-pump coronary bypass grafting and 38.9% in aortic valve replacement. Multivariate analysis of risk factors for AKI identified chronic kidney disease (CKD) (eGFR <60 ml/min/1.73 m(2)) and mild HLBCA time >60 min. Our method of TAR was associated with low mortality and low rate of kidney injury by discharge. However, prolonged mild HLBCA and preoperative CKD might need additional consideration.

Preoperative granisetron for shivering prophylaxis in cesarean section under spinal anesthesia

Background Shivering is one of the common problems during spinal anesthesia and may lead to several complications, interfere with patient monitoring, and is bothersome for the mother while holding her newborn. We performed this prospective, double-blinded, placebo-controlled study to determine the ability of preoperative intravenous (IV) granisetron to prevent or decrease shivering after spinal anesthesia during elective cesarean delivery. Materials and methods A total of 117 ASA I/II parturient women undergoing elective cesarean delivery were enrolled. Patients were randomly allocated into two groups: group G ( n = 58) received 3 mg in 3 ml granisetron intravenously and group P ( n = 59) received 3 ml intravenous normal saline before performing spinal anesthesia. Spinal anesthesia was performed in all patients using 10 mg heavy bupivacaine 0.5% and 15 μg fentanyl. Shivering was graded according to the Wrench score: 0 = no shivering; 1 = piloerection, peripheral vasoconstriction, or peripheral cyanosis without other cause; 2 = visible muscular activity confined to one muscle group; 3 = visible muscular activity in more than one muscle group; and 4 = gross muscular activity involving the entire body. Rescue medication intake, interference with neonatal holding, interference with monitoring, and maternal vomiting in 12 h postoperative as well as tympanic membrane temperature and Apgar score were recorded. Results The percentage of shivering and shivering score value among parturients in both groups did not show significant statistical difference during the study time periods, with a P value greater than 0.05. With respect to rescue medication intake ( P = 0.086) as well as interference with monitoring ( P = 0.653) and neonatal holding ( P = 0.653), there was no statistically significant difference as well. In addition, tympanic membrane temperature ( P = 0.48) and 1-min Apgar score ( P = 0.09) did not show statistically significant difference. Granisetron significantly reduced the incidence of nausea and vomiting during the 12-h postoperative period, with only six (10.3%) mothers in group G complaining of nausea and vomiting in comparison with 16 (27.1%) mothers in group P ( P = 0.036). Conclusion Preoperative intravenous granisetron for shivering prophylaxis in cesarean section under spinal anesthesia did not significantly reduce the incidence or severity of shivering.

Post-operative Hypothermia in Surgical Patients at University of Gondar Hospital, Ethiopia

Background: Hypothermia (i.e., temperature <36°C) is a common incident in the immediate postoperative period. However, it is usually diagnosed and treated infrequently. Maintaining normal body temperature will reduce hospital stay, surgical site infection, postoperative blood transfusions, pressure ulcers, subjective discomfort and mortality. The aim of this study was to identify magnitude and factors associated with postoperative hypothermia. Methods: Hospital based cross sectional study was conducted at University of Gondar Hospital. All consecutive postoperative (N= 384) patients that underwent scheduled or emergency surgery were included. Tympanic membrane temperature was measured before surgery and on arrival at recovery room via clinical nurses. Analysis was done using version 20 SPSS and binary logistic regression was utilized to identify associated factors. Result: The incidence of postoperative hypothermia at Recovery Room was 30.72%. Of these, 30 (27.96%) and 43 (34.44%) were mild and moderate respectively, with no severe hypothermia. Surgical patient operated under general anesthesia was more likely to develop postoperative hypothermia than spinal anesthesia (AOR, 1.84; 95% CI, 1.17; 3.24). Additionally, those with higher ASA physical status were at higher risk of postoperative hypothermia (AOR, 1.99; 95% CI, 1.16; 3.44). Temperature was not routinely taken by health care providers in the preoperative and intraoperative period. Conclusion and recommendation: Incidence of postoperative hypothermia at Recovery Room was high. Patient with high ASA physical status and operated under general anesthesia were significant factors for the development of postoperative hypothermia. Anesthesia providers along with perioperative surgical team should participate to reduce the occurrence of postoperative hypothermia with early prediction and diagnosis, especially in high risk groups.

Interaction between postoperative shivering and hyperalgesia caused by high-dose remifentanil

BackgroundHigh-dose remifentanil-based anesthesia is associated with opioid-induced hyperalgesia (OIH) and postanesthetic shivering (PAS). These effects can be prevented by N-methyl-d-aspartate (NMDA) receptor antagonists. This study aimed to investigate correlations between OIH and PAS caused by high-dose remifentanil and the effects of low-dose ketamine on OIH and PAS.MethodsSeventy-five patients scheduled for single-port laparoscopic gynecologic surgery were randomly allocated into three groups, each of which received intraoperative remifentanil: group L at 0.1 µg/kg/min; group H at 0.3 µg/kg/min; and group HK at 0.3 µg/kg/min plus 0.25 mg/kg ketamine just before incision, followed by a continuous infusion of 5 µg/kg/min ketamine until skin closure.ResultsPAS, postoperative tactile pain threshold, and the extent of hyperalgesia in group H were significantly different (P < 0.05) than in the other two groups. PAS was significantly correlated with OIH, including mechanically evoked pain such as postoperative tactile pain threshold (r = -0.529, P = 0.01) (r = -0.458, P = 0.021) and the extent of hyperalgesia (r = 0.537, P = 0.002) (r = 0.384, P = 0.031), respectively, in group H and group HK. Notably, both groups were treated with high-dose remifentanil. Tympanic membrane temperature, time to first postoperative analgesic requirement, postoperative pain scores, analgesic consumption, and cumulative patient-controlled analgesia volume containing morphine were comparable in all three groups.ConclusionsOIH, including the enhanced perception of pain, and PAS were both associated with high-dose remifentanil, were significantly correlated and were attenuated by a low dose of ketamine. This suggests that a common mechanism in part mediated through activation of the central glutamatergic system (e.g., NMDA receptors), underlies the two effects caused by high doses of remifentanil.

Jugular bulb oxygen saturation and the pyruvate lactate ratio are good signals for cerebral metabolism and oxygenation during hypothermia with altered target ventilation

Background The effect of deliberate hypothermia and hypocapnia on brain protection during neurosurgical procedures has been studied for many years, but in this study, the combination of deliberate hypothermia and hypocapnia was analyzed to detect their effects on cerebral oxygenation by the assessment of SjvO 2 and cerebral metabolism by the measurement of both jugular bulb lactate and pyruvate. Patients and methods Sixty patients scheduled for excision of supratentorial space-occupying lesions were randomly allocated into two groups. In group I, hypocapnia was induced combined with hypothermia, and in group II, normocapnia was maintained combined with hypothermia. Hypothermia was induced using a water blanket under the patient controlling the tympanic membrane temperature at 35°C. Jugular bulb venous and arterial blood gas analyses were performed before the induction of hypothermia ± hypocapnia (baseline), and then every 20 min till closure of the dura. The arterio-jugular venous oxygen content difference (AJDO 2 ) and the cerebral oxygen extraction ratio (COER) were calculated. Jugular bulb lactate and pyruvate levels were measured before the induction of hypothermia ± hypocapnia (baseline) and then every 30 min till closure of the dura. Results There was a significant increase in pjH and significant decreases in both PjCO 2 and SjvO 2 in the hypocapnic group after the induction of hypocapnia. SjvO 2 reached 80.32 ± 4.59% in the normocapnic group, whereas it reached 75.3 ± 4.02% in the hypocapnic group. AJDO 2 and COER started to decrease after induced hypothermia in both groups compared with readings before induced hypothermia, but the hypocapnic group had a significantly higher AJDO 2 and COER than the normocapnic group during the period of induced hypothermia (AJDO 2 reached 3.98 ± 0.47 ml/dl and COER reached 25.93 ± 4.13% in comparison with the hypocapnic group, where AJDO 2 reached 4.58 ± 0.51 ml/dl and COER reached 31.96 ± 4.01%).Jugular bulb lactate and pyruvate levels were significantly higher during hypocapnia than during normocapnia. Conclusion Cerebral oxygenation and metabolism were better during hypothermia combined with normocapnia as reflected by relative ͽͽSjvO 2 and ͿͿAJDO 2 and COER as well as ͿͿjugular bulb lactate and pyruvate.

Impact of low filter resistances on subjective and physiological responses to filtering facepiece respirators.

Ten subjects underwent treadmill exercise at 5.6 km/h over one hour while wearing each of three identical appearing, cup-shaped, prototype filtering facepiece respirators that differed only in their filter resistances (3 mm, 6 mm, and 9 mm H2O pressure drop). There were no statistically significant differences between filtering facepiece respirators with respect to impact on physiological parameters (i.e., heart rate, respiratory rate, oxygen saturation, transcutaneous carbon dioxide levels, tympanic membrane temperature), pulmonary function variables (i.e., tidal volume, respiratory rate, volume of carbon dioxide production, oxygen consumption, or ventilation), and subjective ratings (i.e., exertion, thermal comfort, inspiratory effort, expiratory effort and overall breathing comfort). The nominal filter resistances of the prototype filtering facepiece respirators correspond to airflow resistances ranging from 2.1 - 6.6 mm H2O/L/s which are less than, or minimally equivalent to, previously reported values for the normal threshold for detection of inspiratory breathing resistance (6 - 7.6 mm H2O/L/sec). Therefore, filtering facepiece respirators with filter resistances at, or below, this level may not impact the wearer differently physiologically or subjectively from those with filter resistances only slightly above this threshold at low-moderate work rates over one hour.