[Prewarming according to the AWMF S3 guidelines on preventing inadvertant perioperative hypothermia 2014 : Retrospective analysis of 7786 patients]. / Vorwärmung entsprechend der "S3 Leitlinie Vermeidung von unbeabsichtigter perioperativer Hypothermie 2014" : Retrospektive Analyse von 7786 Patienten.

BACKGROUND: Inadvertent perioperative hypothermia, which is defined as a core body temperature of less than 36.0 °C, can have serious consequences in surgery patients. These include cardiac complications, increased blood loss, wound infections and postoperative shivering; therefore, the scientific evidence that inadvertent perioperative hypothermia should be avoided is undisputed and several national guidelines have been published summarizing the scientific evidence and recommending specific procedures. The German AWMF guidelines were the first to emphasize the importance of prewarming for surgery patients to avoid inadvertant perioperative hypothermia; however, in contrast to intraoperative warming, prewarming is so far not sufficiently implemented in clinical practice in many hospitals. Furthermore, a recent study has questioned the effectiveness of prewarming. OBJECTIVE: The aim of this retrospective investigation was to evaluate the hypothermia rates that can be achieved when prewarming in the anesthesia induction room is introduced into the clinical practice and performed in addition to intraoperative warming. MATERIAL AND METHODS: The ethics committee of the Medical Faculty of the Martin Luther University Halle Wittenberg gave approval for data storage and retrospective data analysis from the anesthesia database. According to the existing local standard operating procedure, prewarming with forced air was performed in addition to intraoperative warming in the anesthesia induction room in 3899 patients receiving general anesthesia with a duration of 30 min or longer from January 2015 to December 2016. The results were compared with a control group of 3887 patients from July 2012 to August 2014 who received intraoperative warming but were not subjected to prewarming. Tracheal intubation was carried out in all patients and temperature measurements after the induction of anesthesia were performed using esophageal, urinary catheter or intra-arterial temperature probes. RESULTS: The mean duration of prewarming was 25 min in the treatment group. Patients subjected to prewarming showed an intraoperative hypothermia rate of 15.8% and a postoperative hypothermia rate of 5.1%. Patients without prewarming showed an intraoperative hypothermia rate of 30.4% and a postoperative hypothermia rate of 12.4%. This means a 52% reduction of the intraoperative hypothermia rate and a 41% reduction of the postoperative hypothermia rate for patients who received prewarmimg (p < 0.0001). Multivariate logistic regression revealed that the lack of prewarming was independently associated with intraoperative hypothermia with an odds ratio of 2.5 (95% confidence interval CI 2.250-2.841; p < 0.0001) and postoperative hypothermia with an odds ratio of 2.8 (95% CI 2.316-3.277; p < 0.0001). CONCLUSION: Prewarming, as recommended in the AWMF guidelines, resulted in a significant and clinically relevant reduction in the incidence of inadvertent perioperative hypothermia; therefore, prewarming can still be regarded as an effective method to avoid perioperative hypothermia. Hypothermia rates of 15.8% intraoperatively and 5.1% postoperatively can be achieved in clinical practice, when prewarming is performed in addition to intraoperative warming in the anesthesia induction room directly before the start of surgical procedures.

End-tidal control vs. manually controlled minimal-flow anesthesia: a prospective comparative trial.

BACKGROUND: To ensure safe general anesthesia, manually controlled anesthesia requires constant monitoring and numerous manual adjustments of the gas dosage, especially for low- and minimal-flow anesthesia. Oxygen flow-rate and administration of volatile anesthetics can also be controlled automatically by anesthesia machines using the end-tidal control technique, which ensures constant end-tidal concentrations of oxygen and anesthetic gas via feedback and continuous adjustment mechanisms. We investigated the hypothesis that end-tidal control is superior to manually controlled minimal-flow anesthesia (0.5 l/min). METHODS: In this prospective trial, we included 64 patients undergoing elective surgery under general anesthesia. We analyzed the precision of maintenance of the sevoflurane concentration (1.2-1.4%) and expiratory oxygen (35-40%) and the number of necessary adjustments. RESULTS: Target-concentrations of sevoflurane and oxygen were maintained at more stable levels with the use of end-tidal control (during the first 15 min 28% vs. 51% and from 15 to 60 min 1% vs. 19% deviation from sevoflurane target, P < 0.0001; 45% vs. 86% and 5% vs. 15% deviation from O2 target, P < 0.01, respectively), while manual controlled minimal-flow anesthesia required more interventions to maintain the defined target ranges of sevoflurane (8, IQR 6-12) and end-tidal oxygen (5, IQR 3-6). The target-concentrations were reached earlier with the use of end-tidal compared with manual controlled minimal-flow anesthesia but required slightly greater use of anesthetic agents (6.9 vs. 6.0 ml/h). CONCLUSIONS: End-tidal control is a superior technique for setting and maintaining oxygen and anesthetic gas concentrations in a stable and rapid manner compared with manual control. Consequently, end-tidal control can effectively support the anesthetist.

Haptoglobin and free haemoglobin during cardiac surgery-is there a link to acute kidney injury?

Acute kidney injury (AKI) is frequently observed after cardiac surgery (CS) with cardiopulmonary bypass (CPB). Multiple mechanisms underlie this phenomenon, including CPB-dependent haemolysis. Haemoglobin is released during haemolysis, and free haemoglobin (frHb) causes tubular cell injury after exceeding the binding capacity of haptoglobin (Hp). The objective of this study was to investigate the influence of perioperative changes in frHb and Hp levels on the incidence of CS-associated (CSA) AKI. After receiving local ethics committee approval and obtaining informed consent from our patients, we analysed the data pertaining to 154 patients undergoing CPB surgery. We recorded frHb and Hp concentrations pre-, intra- and postoperatively and defined AKI using the Kidney Disease Improving Global Outcomes (KDIGO) classification. We observed that frHb levels increased significantly during surgery and then decreased at ten hours thereafter and that Hp levels decreased during surgery and remained at low levels until the first postoperative day. We noted a moderate negative correlation between frHb and Hp levels. AKI was identified in 45.5% of patients; however, there was no significant difference in frHb or Hp levels between patients with and without AKI. We did not observe a relationship between frHb or Hp levels and CSA AKI and thus could not confirm the hypothesis that patients with higher baseline Hp concentrations experience a lower incidence of AKI than patients with lower baseline Hp concentrations.

The effects of residual pump blood on patient plasma free haemoglobin levels post cardiac surgery.

At the end of cardiopulmonary bypass, there are invariably several hundred millilitres of residual pump blood in the reservoir, which can either be re-transfused or discarded. The objective of this prospective observational study was to investigate the quality of the residual pump blood, focusing on plasma free haemoglobin (pfHb) and blood cell counts. Fifty-one consecutive patients were included in the study. Forty-nine units of residual pump blood and 58 units of transfused red blood cell (RBC) concentrates were analysed. The mean preoperative pfHb of the patients was 0.057 ± 0.062 g/l, which increased gradually to 0.55 ± 0.36 g/l on arrival in the intensive care unit postoperatively. On the first postoperative day, the mean pfHb had returned to within the normal range. Our data showed that haemoglobin, haematocrit, and erythrocyte counts of residual pump blood were approximately 40% of the values in standardised RBC concentrates. Plasma free haemoglobin was significantly higher in residual pump blood compared to RBC concentrates, and nearly twice as high as the pfHb in patient blood samples taken contemporaneously. Our findings indicate that residual pump blood pfHb levels are markedly higher compared to patients' blood and RBC concentrates, but that its administration does not significantly increase patients' pfHb levels.

[Prewarming. Yesterday's luxury, today's minimum requirement]. / Vorwärmung. Von der Kür zur Pflicht.

Prewarming is a useful and effective measure to reduce perioperative hypothermia. Due to §23(3) of the German Infektionsschutzgesetz (Gesetz zur Verhütung und Bekämpfung von Infektionskrankheiten beim Menschen, Infection Act, act on protection and prevention of infectious diseases in man) and the recommendations of the Hospital Hygiene and Infection Prevention Committee of the Robert Koch Institute, implementation of prewarming is clearly recommended. There are several technically satisfactory and practicable devices available allowing prewarming on the normal hospital ward, in the preoperative holding area or in the induction room of the operating theater (OR) The implementation of prewarming requires additional equipment and training of staff. Using a locally adapted concept for the implementation of prewarming does not lead to inefficiency in the perioperative process. In contrast, the implementation can help to achieve stable arrival times for patients in the OR.