Intraoperative zero-heat-flux thermometry overestimates nasopharyngeal temperature by 0.39 °C: an observational study in patients undergoing congenital heart surgery.

During surgery for congenital heart disease (CHD) temperature management is crucial. Vesical (Tves) and nasopharyngeal (TNPH) temperature are usually measured. Whereas Tves slowly responds to temperature changes, TNPH carries the risk of bleeding. The zero-heat-flux (ZHF) temperature monitoring systems SpotOn™ (TSpotOn), and Tcore™ (Tcore) measure temperature non-invasively. We evaluated accuracy and precision of the non-invasive devices, and of Tves compared to TNPH for estimating temperature. In this prospective observational study in pediatric and adult patients accuracy and precision of TSpotOn, Tcore, and Tves were analyzed using the Bland-Altman method. Proportion of differences (PoD) and Lin´s concordance correlation coefficient (LCC) were calculated. Data of 47 patients resulted in sets of matched measurements: 1073 for TSpotOn vs. TNPH, 874 for Tcore vs. TNPH, and 1102 for Tves vs. TNPH. Accuracy was - 0.39 °C for TSpotOn, -0.09 °C for Tcore, and 0.07 °C for Tves. Precisison was between - 1.12 and 0.35 °C for TSpotOn, -0.88 to 0.71 °C for Tcore, and - 1.90 to 2.05 °C for Tves. PoD ≤ 0.5 °C were 71% for TSpotOn, 71% for Tcore, and 60% for Tves. LCC was 0.9455 for TSpotOn, 0.9510 for Tcore, and 0.9322 for Tves. Temperatures below 25.2 °C (TSpotOn) or 27.1 (Tcore) could not be recorded non-invasively, but only with Tves. Trial registration German Clinical Trials Register, DRKS00010720.

Evaluation of the Temple Touch Pro™ noninvasive core-temperature monitoring system in 100 adults under general anesthesia: a prospective comparison with esophageal temperature.

Perioperative hypothermia is still common and has relevant complication for the patient. An effective perioperative thermal management requires essentially an accurate method to measure core temperature. So far, only one study has investigated the new Temple Touch Pro™ (Medisim Ltd., Beit-Shemesh, Israel). during anesthesia Therefore, we assessed the agreement between the Temple Touch Pro™ thermometer (TTP) and distal esophageal temperature (TEso) in a second study. After approval by the local ethics committee we studied 100 adult patients undergoing surgery with general anesthesia. Before induction of anesthesia the TTP sensor unit was attached to the skin above the temporal artery. After induction of anesthesia an esophageal temperature probe was placed in the distal esophagus. Recordings started 10 min after placement of the esophageal temperature probe to allow adequate warming of the probes. Pairs of temperature values were documented in five-minute intervals until emergence of anesthesia. Accuracy of the two methods was assessed by Bland-Altman comparisons of differences with multiple measurements. Core temperatures obtained with the TTP in adults showed a mean bias of -0.04 °C with 95% limits of agreement within - 0.99 °C to + 0.91 °C compared to an esophageal temperature probe. We consider the TTP as a reasonable tool for perioperative temperature monitoring. It is not accurate enough to be used as a reference method in scientific studies, but may be a useful tool especially for conscious patients undergoing neuraxial anesthesia or regional anesthesia with sedation. Trial registration This study was registered in the German Clinical Trials Register (DRKS-ID: 00024050), day of registration 12/01/2021.

Transesophageal echocardiography for perioperative management in thoracic surgery.

PURPOSE OF REVIEW: Perioperative transesophageal echocardiography (TEE) is most often employed during cardiac surgery. This review will summarize some of the recent findings relevant to TEE utilization during thoracic surgical procedures. RECENT FINDINGS: Hemodynamic monitoring is a key component of goal-directed fluid therapy, which is also becoming more common for management of thoracic surgical procedures. Although usually not required for the anesthetic management of common thoracic surgeries, TEE is frequently used during lung transplantation and pulmonary thromboendarterectomy. Few clinical studies support current practice patterns, and most recommendations are based on expert opinion. SUMMARY: Currently, routine use of TEE in thoracic surgery is often limited to specific high-risk patients and/or procedures. As in other perioperative settings, TEE may be utilized to elucidate the reasons for acute hemodynamic instability without apparent cause. Contraindications to TEE apply and have to be taken into consideration before performing a TEE on a thoracic surgical patient.

Genome-wide association study of myocardial infarction, atrial fibrillation, acute stroke, acute kidney injury and delirium after cardiac surgery - a sub-analysis of the RIPHeart-Study.

BACKGROUND: The aim of our study was the identification of genetic variants associated with postoperative complications after cardiac surgery. METHODS: We conducted a prospective, double-blind, multicenter, randomized trial (RIPHeart). We performed a genome-wide association study (GWAS) in 1170 patients of both genders (871 males, 299 females) from the RIPHeart-Study cohort. Patients undergoing non-emergent cardiac surgery were included. Primary endpoint comprises a binary composite complication rate covering atrial fibrillation, delirium, non-fatal myocardial infarction, acute renal failure and/or any new stroke until hospital discharge with a maximum of fourteen days after surgery. RESULTS: A total of 547,644 genotyped markers were available for analysis. Following quality control and adjustment for clinical covariate, one SNP reached genome-wide significance (PHLPP2, rs78064607, p = 3.77 × 10- 8) and 139 (adjusted for all other outcomes) SNPs showed promising association with p < 1 × 10- 5 from the GWAS. CONCLUSIONS: We identified several potential loci, in particular PHLPP2, BBS9, RyR2, DUSP4 and HSPA8, associated with new-onset of atrial fibrillation, delirium, myocardial infarction, acute kidney injury and stroke after cardiac surgery. TRIAL REGISTRATION: The study was registered with ClinicalTrials.gov NCT01067703, prospectively registered on 11 Feb 2010.

A Multicenter Trial of Remote Ischemic Preconditioning for Heart Surgery.

BACKGROUND: Remote ischemic preconditioning (RIPC) is reported to reduce biomarkers of ischemic and reperfusion injury in patients undergoing cardiac surgery, but uncertainty about clinical outcomes remains. METHODS: We conducted a prospective, double-blind, multicenter, randomized, controlled trial involving adults who were scheduled for elective cardiac surgery requiring cardiopulmonary bypass under total anesthesia with intravenous propofol. The trial compared upper-limb RIPC with a sham intervention. The primary end point was a composite of death, myocardial infarction, stroke, or acute renal failure up to the time of hospital discharge. Secondary end points included the occurrence of any individual component of the primary end point by day 90. RESULTS: A total of 1403 patients underwent randomization. The full analysis set comprised 1385 patients (692 in the RIPC group and 693 in the sham-RIPC group). There was no significant between-group difference in the rate of the composite primary end point (99 patients [14.3%] in the RIPC group and 101 [14.6%] in the sham-RIPC group, P=0.89) or of any of the individual components: death (9 patients [1.3%] and 4 [0.6%], respectively; P=0.21), myocardial infarction (47 [6.8%] and 63 [9.1%], P=0.12), stroke (14 [2.0%] and 15 [2.2%], P=0.79), and acute renal failure (42 [6.1%] and 35 [5.1%], P=0.45). The results were similar in the per-protocol analysis. No treatment effect was found in any subgroup analysis. No significant differences between the RIPC group and the sham-RIPC group were seen in the level of troponin release, the duration of mechanical ventilation, the length of stay in the intensive care unit or the hospital, new onset of atrial fibrillation, and the incidence of postoperative delirium. No RIPC-related adverse events were observed. CONCLUSIONS: Upper-limb RIPC performed while patients were under propofol-induced anesthesia did not show a relevant benefit among patients undergoing elective cardiac surgery. (Funded by the German Research Foundation; RIPHeart ClinicalTrials.gov number, NCT01067703.).

REM sleep-like episodes of motoneuronal depression and respiratory rate increase are triggered by pontine carbachol microinjections in in situ perfused rat brainstem preparation.

Hypoglossal nerve activity (HNA) controls the position and movements of the tongue. In persons with compromised upper airway anatomy, sleep-related hypotonia of the tongue and other pharyngeal muscles causes increased upper airway resistance, or total upper airway obstructions, thus disrupting both sleep and breathing. Hypoglossal nerve activity reaches its nadir, and obstructive episodes are longest and most severe, during rapid eye movement stage of sleep (REMS). Microinjections of a cholinergic agonist, carbachol, into the pons have been used in vivo to investigate the mechanisms of respiratory control during REMS. Here, we recorded inspiratory-modulated phrenic nerve activity and HNA and microinjected carbachol (25-50 nl, 10 mm) into the pons in an in situ perfused working heart-brainstem rat preparation (WHBP), an ex vivo model previously validated for studies of the chemical and reflex control of breathing. Carbachol microinjections were made into 40 sites in 33 juvenile rat preparations and, at 24 sites, they triggered depression of HNA with increased respiratory rate and little change of phrenic nerve activity, a pattern akin to that during natural REMS in vivo. The REMS-like episodes started 151 ± 73 s (SD) following microinjections, lasted 20.3 ± 4.5 min, were elicited most effectively from the dorsal part of the rostral nucleus pontis oralis, and were prevented by perfusion of the preparation with atropine. The WHBP offers a novel model with which to investigate cellular and neurochemical mechanisms of REMS-related upper airway hypotonia in situ without anaesthesia and with full control over the cellular environment.

Anesthetic effects on synaptic transmission and gain control in respiratory control.

All volatile and most intravenous general anesthetics currently in clinical use cause respiratory depression at concentrations suitable for surgery. While various in vitro studies have identified potential molecular targets, their contributions to respiratory depression are poorly understood. At surgical concentrations, anesthetics principally affect ligand-gated, rather than voltage-gated ion channels. Here we focus on anesthetic-induced effects on synaptic transmission in brainstem respiratory neurons. The spontaneous discharge patterns of canine respiratory bulbospinal premotor neurons in vivo depend principally on NMDA and non-NMDA receptor-mediated excitation, while GABAA receptors mediate gain modulation and silent-phase inhibition. Studies examining the effects of volatile anesthetics on synaptic neurotransmission to these neurons suggest a primary role for postsynaptic enhancement of GABAA receptor function, partly offset by a reduction in presynaptic inhibition and a presynaptic reduction in glutamatergic excitation. In studies involving canine inspiratory hypoglossal motoneurons in vivo, which are already strongly depressed by low concentrations (< 0.5 MAC) of volatile anesthetics, the role of acid-sensitive, two-pore domain K+ (TASK) channels was found to be minimal at these subanesthetic concentrations. Potentiation of GABAA receptor-mediated inhibition was suggested. These studies on canine respiratory neurons provide valuable insights into mechanisms of anesthetic depression within a respiratory control subsystem; future studies will be required to determine anesthetic effects on sources of respiratory drive, rhythm, and their control.

Major components of endogenous neurotransmission underlying the discharge activity of hypoglossal motoneurons in vivo.

Multibarrel micropipettes were used to simultaneously record unit activity and apply antagonists on individual inspiratory hypoglossal motoneurons (IHMNs) to determine the endogenous activation levels of NMDA, non-NMDA, GABA(A) and serotonin receptors responsible for the IHMN spontaneous discharge patterns in decerebrate dogs. IHMN activity is highly dependent on glutamatergic phasic and tonic drives, which are differentially mediated by the receptor subtypes. Endogenous serotonin significantly amplifies IHMN activity, while GABAergic gain modulation acts to attenuate activity. Thus, alterations in the neurotransmission of any of these systems could markedly alter neuronal output to target muscles.

Association between perioperative hypothermia and patient outcomes after thoracic surgery: A single center retrospective analysis.

Hypothermia due to anaesthetic-induced impairment of thermoregulatory control and exposure to a cool environment is common in surgical patients. Peripheral vasodilation due to neuroaxial blockade may aggravate hypothermia. There is few data on perioperative hypothermia in patients undergoing thoracic surgery under combined general and regional anesthesia. We reviewed all thoracic surgical patients between 2006 and 2011 to determine the incidence and extent of hypothermia with or without an epidural anesthesia and evaluated its effect.Around 339 patients underwent lung resection procedures with intraoperative forced-air warming: 197 with general and epidural anesthesia (GA + EPI), 199 with general anesthesia alone (GA). Statistical analyses were performed to determine the association between hypothermia (T < 36°C) and transfusion requirements, length of stay (LOS) in the intensive care unit (ICU), hospital LOS, and in hospital mortality.The overall incidence of hypothermia was 64.3%. Multivariate regression analysis revealed three significant risk factors for the development of hypothermia: long induction time (P = .011), small body surface area (P = .003), and application of more fluid intraoperatively (P < .001). Factors determining the extent of hypothermia were: receiving an open thoracotomy (P = .009), placement and use of an epidural catheter (P = .002), and a lower body mass index (BMI) (P < .001). Additional epidural anesthesia reduced core temperature by 0.26°C (95% CI -0.414 to -0.095°C, P < .05). There was no difference in transfusion requirements, ICU LOS or mortality between both groups. Hospital LOS was longer in patients with hypothermia.More than half of all thoracic patients suffered from hypothermia. A long induction time, small body surface area, and large intraoperative fluid application were independent risk factors for the development of perioperative hypothermia. Additional epidural anesthesia to general anesthesia did not increase the incidence of hypothermia but decreased body core temperature to an-albeit not clinically significant-degree. Patients scheduled for thoracic surgery will probably benefit from an additional period of prewarming prior to induction to reduce the high incidence of perioperative hypothermia.

RIPHeart (Remote Ischemic Preconditioning for Heart Surgery) Study: Myocardial Dysfunction, Postoperative Neurocognitive Dysfunction, and 1 Year Follow-Up.

BACKGROUND: Remote ischemic preconditioning (RIPC) has been suggested to protect against certain forms of organ injury after cardiac surgery. Previously, we reported the main results of RIPHeart (Remote Ischemic Preconditioning for Heart Surgery) Study, a multicenter trial randomizing 1403 cardiac surgery patients receiving either RIPC or sham-RIPC. METHODS AND RESULTS: In this follow-up paper, we present 1-year follow-up of the composite primary end point and its individual components (all-cause mortality, myocardial infarction, stroke and acute renal failure), in a sub-group of patients, intraoperative myocardial dysfunction assessed by transesophageal echocardiography and the incidence of postoperative neurocognitive dysfunction 5 to 7 days and 3 months after surgery. RIPC neither showed any beneficial effect on the 1-year composite primary end point (RIPC versus sham-RIPC 16.4% versus 16.9%) and its individual components (all-cause mortality [3.4% versus 2.5%], myocardial infarction [7.0% versus 9.4%], stroke [2.2% versus 3.1%], acute renal failure [7.0% versus 5.7%]) nor improved intraoperative myocardial dysfunction or incidence of postoperative neurocognitive dysfunction 5 to 7 days (67 [47.5%] versus 71 [53.8%] patients) and 3 months after surgery (17 [27.9%] versus 18 [27.7%] patients), respectively. CONCLUSIONS: Similar to our main study, RIPC had no effect on intraoperative myocardial dysfunction, neurocognitive function and long-term outcome in cardiac surgery patients undergoing propofol anesthesia. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01067703.