Influence of oral premedication and prewarming on core temperature of cardiac surgical patients: a prospective, randomized, controlled trial.

BACKGROUND: Perioperative hypothermia is still very common and associated with numerous adverse effects. The effects of benzodiazepines, administered as premedication, on thermoregulation have been studied with conflicting results. We investigated the hypotheses that premedication with flunitrazepam would lower the preoperative core temperature and that prewarming could attenuate this effect. METHODS: After approval by the local research ethics committee 50 adult cardiac surgical patients were included in this prospective, randomized, controlled, single-centre study with two parallel groups in a university hospital setting. Core temperature was measured using a continuous, non-invasive zero-heat flux thermometer from 30 min before administration of the oral premedication until beginning of surgery. An equal number of patients was randomly allocated via a computer-generated list assigning them to either prewarming or control group using the sealed envelope method for blinding. The intervention itself could not be blinded. In the prewarming group patients received active prewarming using an underbody forced-air warming blanket. The data were analysed using Student's t-test, Mann-Whitney U-test and Fisher's exact test. RESULTS: Of the randomized 25 patients per group 24 patients per group could be analysed. Initial core temperature was 36.7 ± 0.2 °C and dropped significantly after oral premedication to 36.5 ± 0.3 °C when the patients were leaving the ward and to 36.4 ± 0.3 °C before induction of anaesthesia. The patients of the prewarming group had a significantly higher core temperature at the beginning of surgery (35.8 ± 0.4 °C vs. 35.5 ± 0.5 °C, p = 0.027), although core temperature at induction of anaesthesia was comparable. Despite prewarming, core temperature did not reach baseline level prior to premedication (36.7 ± 0.2 °C). CONCLUSIONS: Oral premedication with benzodiazepines on the ward lowered core temperature significantly at arrival in the operating room. This drop in core temperature cannot be offset by a short period of active prewarming. TRIAL REGISTRATION: This trial was prospectively registered with the German registry of clinical trials under the trial number DRKS00005790 on 20th February 2014.

Comparison of Conductive and Convective Warming in Patients Undergoing Video-Assisted Thoracic Surgery: A Prospective Randomized Clinical Trial.

Background Perioperative hypothermia is frequent during thoracic surgery. After approval by the local ethics committee and written informed consent from patients, we examined the efficiency of prewarming and intraoperative warming with a convective warming system and conductive warming system to prevent perioperative hypothermia during video-assisted thoracic surgery (VATS). Methods We randomized 60 patients with indication for VATS in two groups (convective warming with an underbody blanket vs. conductive warming with an underbody mattress and additional warming of the legs). All patients were prewarmed before induction of anesthesia with the corresponding system. Core temperature was measured sublingual and in the nasopharynx. Results Both groups were not significantly different in regard to clinical parameter, prewarming, and initial core temperature. The patients in conduction group had lower intraoperative core temperatures and a higher incidence of intraoperative (73.9 vs. 24%) and postoperative hypothermia (56.5 vs. 8%) compared with convective warming. Conclusions Pre- and intraoperative convective warming with an underbody blanket prevents perioperative hypothermia during VATS better than conductive warming. The inferior prevention in conductive warming group may be caused by reduced body contact to the warming mattresses in lateral position.

Working with estimation-formulas to predict nasopharyngeal airway insertion depth in children: Looking at magnetic resonance images - A prospective observational study (WEND:LI-Study).

OBJECTIVE: To determine the accuracy of the recently proposed landmark-method 'nostril-to-tragus minus 10 mm' and compare with ERC-recommended distances for nasopharyngeal airway length sizing in children. METHOD: We conducted a prospective observational study in sedated children < 12 years. Nasopharyngeal airways were inserted following 'nostril-to-tragus minus 10 mm'. Primary outcome was the rate of nasopharyngeal airway tips between soft palate and epiglottis on magnetic resonance imaging (MRI) indicated for medical reasons. An optimal placement was defined when the tip lied within 25-75% of the total soft palate-to-epiglottis distance. Between 0-100% of this distance, placement was still considered acceptable, below 0% too proximal or above 100% too distal. Secondary outcomes were the rate of adverse events, the qualitative positions of airway tips, and the comparison of ́nostril-to-tragus minus 10 mm with the ERC-recommended distances 'nostril-to-angle of the mandible' and 'nostril-to-tragus' with objective MRI measurements. RESULTS: We analysed 92 patients with a mean age of 4.3 years. Nasopharyngeal airways were optimally placed in 37.0% (8.7% too proximal-77.2% acceptable-14.1% too distal). Three qualitative malpositions, but no airway-associated adverse event occurred. Objective measurements on MRI revealed the probability of 40.2% optimally placed nasopharyngeal airways (5.4%-67.4%-27.2%) for 'nostril-to-tragus minus 10 mm', 38.0% (17.4%-58.7%-23.9%) for 'nostril-to-mandible' and 13.0% (0%-28.3%-71.7%) for 'nostril-to-tragus', respectively. CONCLUSION: No landmark-method predicted nasopharyngeal airway position reliably. 'Nostril-to-tragus minus 10 mm' seems the least inaccurate one and could be a valuable approximation until another estimation-formula proves more accurate. During insertion, careful clinical evaluation of airway patency is crucial. REGISTERED CLINICAL TRIAL: German Clinical Trials Register; DRKS00021007.

Accuracy of zero-heat-flux thermometry and bladder temperature measurement in critically ill patients.

Core temperature (TCore) monitoring is essential in intensive care medicine. Bladder temperature is the standard of care in many institutions, but not possible in all patients. We therefore compared core temperature measured with a zero-heat flux thermometer (TZHF) and with a bladder catheter (TBladder) against blood temperature (TBlood) as a gold standard in 50 critically ill patients in a prospective, observational study. Every 30 min TBlood, TBladder and TZHF were documented simultaneously. Bland-Altman statistics were used for interpretation. 7018 pairs of measurements for the comparison of TBlood with TZHF and 7265 pairs of measurements for the comparison of TBlood with TBladder could be used. TBladder represented TBlood more accurate than TZHF. In the Bland Altman analyses the bias was smaller (0.05 °C vs. - 0.12 °C) and limits of agreement were narrower (0.64 °C to - 0.54 °C vs. 0.51 °C to - 0.76 °C), but not in clinically meaningful amounts. In conclusion the results for zero-heat-flux and bladder temperatures were virtually identical within about a tenth of a degree, although TZHF tended to underestimate TBlood. Therefore, either is suitable for clinical use.German Clinical Trials Register, DRKS00015482, Registered on 20th September 2018, http://apps.who.int/trialsearch/Trial2.aspx?TrialID=DRKS00015482 .

Perioperative Blood Glucose Levels <150 mg/dL are Associated With Improved 5-Year Survival in Patients Undergoing On-Pump Cardiac Surgery: A Prospective, Observational Cohort Study.

Hyperglycemia is common during and after Coronary Artery Bypass Graft Surgery (CABGS) and has been shown to be associated with poor clinical outcomes. In this study, we hypothesized that a moderate perioperative mean blood glucose level of <150 mg/dL improves long-term survival in cardiac surgery patients. We conducted a prospective, observational cohort study in the heart center of the University Medical Center of Goettingen, Germany. Patients undergoing on-pump cardiac surgery were enrolled in this investigation. After evaluating perioperative blood glucose levels, patients were classified into 2 groups based on mean glucose levels: Glucose ≥150 mg/dL and Glucose <150 mg/dL. Patients were followed up for 5 years, and mortality within this period was recorded as the primary outcome parameter. Secondary outcome parameters included the length of ICU stay, the use of inotropic agents, the length of hospital stay, and the in-hospital mortality. A total of 455 consecutive patients who underwent cardiac surgery with cardiopulmonary bypass were enrolled in this investigation. A Kaplan-Meier survival analysis of the 5-year mortality risk revealed a higher mortality risk among patients with glucose levels ≥150 mg/dL (P = 0.0043, log-rank test). After adjustment for confounders in a multivariate Cox regression model, the association between glucose ≥150 mg/dL and 5-year mortality remained significant (hazard ratio, 2.10; 95% CI, 1.30-3.39; P = 0.0023). This association was corroborated by propensity score matching, in which Kaplan-Meier survival analysis demonstrated significant improvement in the 5-year survival of patients with glucose levels <150 mg/dL (P = 0.0339). Similarly, in-hospital mortality was significantly higher in patients with glucose ≥150 mg/dL compared with patients with glucose <150 mg/dL. Moreover, patients in the Glucose ≥150 mg/dL group required significantly higher doses of the inotropic agent Dobutamine (mg/d) compared with patients in the Glucose <150 mg/dL group (20.6 ±â€Š62.3 and 10.5 ±â€Š40.7, respectively; P = 0.0104). Moreover, patients in the Glucose ≥150 mg/dL group showed a significantly longer hospital stay compared with patients in the Glucose <150 mg/dL group (28 ±â€Š23 and 24 ±â€Š19, respectively; P = 0.0297). We conclude that perioperative blood glucose levels <150 mg/dL are associated with improved 5-year survival in patients undergoing cardiac surgery. More studies are warranted to explain this effect.