Optimization of mRNA extraction from human nasal mucosa biopsies for gene expression profile analysis by qRT-PCR.

Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) is the gold-standard method for analyzing modifications in gene expression in cells and tissues. However, large quantities of high-quality RNA samples are needed for analyzing the expression of multiple genes from one human tissue sample. Here, we provide an optimized protocol for extracting large amounts of RNA from human nasal mucosal biopsies. The quality and quantity of samples were sufficient for qRT-PCR analyses of the expressions of various genes, in duplicate. In contrast to other protocols, we optimized RNA isolation to increase the amount from nasal biopsy samples for analyses of multiple genes. In most previous publications, expressions of only one or a few genes, including housekeeping genes, were analyzed because the amount of biological material was small. We were able to improve our protocol with respect to the yield and quality of RNA. This is likely to produce better results from molecular analyses of very small biopsy samples of human nasal mucosa.

[Intraoperative vascular air embolism : Evidence for risks, diagnostics and treatment]. / Intraoperative vaskuläre Luftembolie : Evidenz bei Risiko, Diagnostik und Therapie.

The entry of gases into the vascular system is called vascular air embolism (VAE). The blocking of the pulmonary circulation by VAE can lead to fulminant right-sided heart failure and cardiocirculatory arrest. A VAE can occur at any time if there is an open connection between the environment and a venous vessel with subatmospheric pressure. This situation occurs during ear nose throat surgery, hip surgery, surgery of the lesser pelvis or breast surgery, if the surgical field is above the level of the heart; however, a VAE can also occur during routine tasks, such as insertion or removal of a central venous catheter or during endoscopic procedures with the insufflation of gas.Because during these procedures VAE is not the main focus of the anesthesia or surgery personnel, in such situations its sudden unexpected occurrence can have severe consequences. In contrast, in cardiac surgery or neurosurgery the risk of intraoperative VAE is much better known. In procedures with a higher risk of a clinically relevant VAE, a patent foramen ovale should be ruled out by preoperative transesophageal echocardiography (TEE). Intraoperatively TEE is the most sensitive procedure not only to detect a VAE but also to visualize the clinical expression, e.g. acute right heart overload.The avoidance of an initial and repeated air embolism is the primary measure to minimize the incidence and severity of VAE.Intraoperatively the following measures should be undertaken: excellent communication between anesthesia and surgery personnel with predetermined actions, maintenance of normal volume, patient positioning with minimal difference in height between heart and head, state of the art surgical technique with closure of potential air entry sites, sufficient detection of air by TEE, repeated jugular vein compression during neurosurgery, intraoperative Trendelenburg positioning of the patient during persisting or clinically evident VAE, differentiated adjustment of ventilatory settings and catecholamine treatment, aspiration of the blood-air mixture (air lock) at the junction of the superior vena cava and right atrium through a large bore central venous line and keeping check of the coagulation status.

Aluminium release by coated and uncoated fluid-warming devices.

The use of fluid-warming systems is recommended for infusion rates > 500 ml.h-1 to avoid peri-operative hypothermia. Some fluid-warming devices use disposable aluminium-heated plates for heat transfer, but there is no protective coating to separate the fluid from the heated aluminium surface. It is unknown if this could promote release of aluminium into infusion fluids. We investigated a coated (Fluido compact) and an uncoated (enFlow) fluid-warming device using normal saline or balanced electrolyte solution as infusion fluids, pumped through the heated disposables at flow rates of 2, 4 and 8 ml.min-1 for 60 min each. Aluminium concentrations in the fluid samples were analysed using graphite furnace atomic absorption spectrometry. With saline the coated and uncoated devices yielded aluminium concentrations below the level of quantification (< 128 µg.l-1 ). Similarly, balanced electrolyte solution in the coated device yielded aluminium concentrations < 128 µg.l-1 . However, balanced electrolyte solution in the uncoated device yielded aluminium concentrations of up to 6794 (3465-8002 [1868-7421]) µg.l-1 . Repeating this last study at a flow rate of 2 ml.min-1 resulted in quite high aluminium concentrations when the uncoated device was not heated (~1000 µg.l-1 ) and higher concentrations after the device was heated. We conclude that using uncoated aluminium plates in fluid-warming systems can lead to a risk of administering potentially harmful concentrations of aluminium when balanced crystalloid solutions are used. The mechanism is unclear, but heat is in part involved. Coating for aluminium within medical devices in direct contact with infusion fluids should be recommended.

[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.

[Neurophysiological monitoring during surgical procedures]. / Neurophysiologisches Monitoring bei operativen Eingriffen.

The application of intraoperative neurophysiological monitoring (IONM) is gaining more and more importance in daily clinical practice. The use of IONM allows the localization of neural structures and to control functioning of the peripheral and central nervous systems in anesthetized patients. This enables surgeons to identify and to protect neural structures and cerebral areas. The use of IONM also enables anesthesiologists to adjust anesthesia and cardiopulmonary therapy to the individual needs of the patient. Thereby, it may be possible to reduce the incidence of postoperative delirium and the incidence of postoperative cognitive deficits. To exploit the full potential anesthesiologists and surgeons must be able to use the methods of IONM safely and understand the results; therefore, basic knowledge of the technology, options and limitations of IONM is necessary. It is also important to be aware of the influence of anesthetics on the methods of IONM. Total intravenous anesthesia (TIVA) is the anesthetic method of choice, because it has only minimal influence on IONM methods. It is important to avoid bolus injections of hypnotics to achieve stable blood concentrations. Long- acting neuromuscular blocking agents should be avoided, because they disturb the signals of electromyography and motor-evoked potentials. By using IONM anesthesiologists and surgeons can identify changes in the function of the peripheral and central nervous system prior to irreversible damage.

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.

[Prevention of perioperative hypothermia : Implementation of the S3 guideline]. / Vermeidung perioperativer Hypothermie : Umsetzung der S3-Leitlinie.

To improve perioperative quality and patient safety, the German S3 guideline should be consistently implemented to avoid perioperative hypothermia. Perioperative normothermia is a quality indicator and should be achieved by anesthesiologists and surgeons. To detect hypothermia early during the perioperative process, measuring body temperature should be started 1-2 h preoperatively. Patients should be actively warmed for 20-30 min before starting anesthesia. Prewarming is most effective and should be included in the preoperative process. Patients should be informed about the risks of perioperative hypothermia and members of the perioperative team should be educated. A standard operating procedure (SOP) to avoid hypothermia should be introduced in every operative unit. The incidence of postoperative hypothermia should be evaluated in operative patients every 3-6 months. The goals should be to measure body temperature in >80% of patients undergoing surgery and for >70% to exhibit a core temperature >36 °C at the end of surgery.

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.

[Tracheal bronchus and contralateral pneumonectomy]. / Trachealer Bronchusabgang und kontralaterale Pneumonektomie.

One-lung ventilation is a standard procedure for many types of lung surgery. The anesthesiologist can be challenged if unknown anomalies of the bronchial tree occur. We report a patient with a tracheal bronchus on the right side presenting for left pneumonectomy, and present one possible solution to airway management.

[Implementation of a thermal management concept to prevent perioperative hypothermia : Results of a 6­month period in clinical practice]. / Umsetzung eines Wärmemanagementkonzeptes zur Vermeidung von perioperativer Hypothermie : Ergebnisse eines Sechsmonatszeitraums in der klinischen Praxis.

BACKGROUND: Perioperative hypothermia is defined as a core temperature below 36 °C. The literature shows that perioperative hypothermia is a frequent but potentially preventable complication of the surgical process. The risk of experiencing perioperative hypothermia is inherent for all anesthetized patients, independent of the type of surgery. Unless preventative measures are taken, perioperative hypothermia occurs in 50 to 70 % of all surgical patients. In Germany and Austria the guideline "Preventing inadvertent perioperative hypothermia" has been published. In Wolfsburg we started already in 2012 with a standard operating procedure to prevent perioperative hypothermia in all surgical patients. In two clinical departments we established an additional prewarming-protocol starting prior to induction of anaesthesia on the normal ward on the day of surgery. MATERIAL AND METHODS: For a period of 6 months we analyzed all temperature data of patients having undergone surgery, beginning before the start of general anaesthesia until the end of the operation. RESULTS: In total 3228 patients were enrolled into the study. Prewarming was performed in 1329 patients. In 1902 patients active warming was limited to the intraoperative period. The total rate of hypothermia in all patients was 32.6 %, whereas the rate of hypothermia at the end of the operation was 19.3 %. In the group of patients without prewarming the overall rate was 39.1 vs. 25 % at the end of the operation. In the groups of patients with prewarming the total rates of hypothermia were 25.2 and 24.7 % overall and 14.4 and 12.5 % at the end of the operation. In multifactorial regression it could be shown that patients without prewarming had a 1.8-fold increased risk of perioperative hypothermia compared to patients with intraoperative warming only. CONCLUSION: We conclude that temperature management is a challenge in the clinical situation, and that it is difficult to achieve rates of hypothermia close to zero. The addition of prewarming was very effective in improving the results in our patients.

Efficacy of a novel prewarming system in the prevention of perioperative hypothermia. A prospective, randomized, multicenter study.

BACKGROUND: Perioperative hypothermia is a common complication during general anesthesia. Although rewarming of patients before surgery has been used as a preventive measure and some guidelines recommend it, the implementation of prewarming for every surgical patient is cumbersome. Therefore, we sought to determine the efficacy of two novel prewarming methods that could facilitate prewarming in daily practice. METHODS: This was a prospective, randomized, multi-center, controlled study. After IRB approval and informed consent, 90 patients undergoing surgery of 30-120 min duration with general anesthesia were randomly assigned to three groups: 1) standard preoperative insulation (Group A); 2) passive preoperative insulation with a commercial prewarming suit (Group B); 3) active preoperative prewarming with a forced-air warmer connected to a prewarming suit (Group C). All patients received warmed IV fluids and intraoperative forced air warming after induction of anesthesia. Oral temperatures were recorded in the preoperative and postoperative periods. Intraoperative core temperatures were measured with an esophageal probe. RESULTS: Repeated-measures analysis of variance (ANOVA) and post hoc Scheffé's test identified a significantly higher core temperature in the actively prewarmed group (Group C) compared to both passive groups (A, B) at 15, 30, 45, 60, and 75 min (P<0.05) after induction of anesthesia and at the end of surgery. During the first 30 min after admission at PACU, also higher oral temperatures were measured in Group C, compared with both passive insulation groups. CONCLUSION: In our study active prewarming with a forced-air warmer and an insulating prewarming suit achieves significantly higher core temperatures during anesthesia and at the end of surgery and avoids hypothermia at the end of surgery compared to commercial or conventional insulation techniques.

Hypoglycaemia and predisposing factors among clinical subgroups treated with intensive insulin therapy.

BACKGROUND: In previous studies, conflicting intensive insulin therapy (IIT) results have been observed, whereby IIT-related mortality seems to be lower in specific clinical subgroups. The aim of this study was to assess differences in glycaemic control, the risk of critical hypoglycaemia (≤ 2.2 mmol/l), the associated predisposing factors, and the in-hospital mortality in different clinical subgroups treated with IIT. METHODS: Prospective, observational study in a university-affiliated intensive care unit (ICU) conducted from 2004 to 2005. All patients (n = 1667) belonging to one of the six most common surgical intervention groups (cardiac, neuro, abdominal, vascular, orthopaedic, and spinal surgeries) and medical patients were included. IIT was performed with a target blood glucose level of 4.4-7.8 mmol/l. Different indices were analysed to evaluate glucose control and glycaemic variability. RESULTS: The rate of critical hypoglycaemia was significantly different within the different clinical subgroups and varied from 0.8% to 4.5%. Similar results were obtained for hyperglycaemia. Multivariable analyses for the predisposing factors of critical hypoglycaemia showed a heterogeneous distribution pattern among the different clinical subgroups. Similar results were obtained for the risk factors of in-hospital mortality. CONCLUSION: The risk of critical hypoglycaemia and the associated predisposing factors depended on the clinical subgroup involved. Critical hypoglycaemia is a potential threat for our patients, and the high risk of critical hypoglycaemia in some clinical subgroups appeared to reverse the benefits of IIT. As a result, it is crucial that the different subgroups involved in a study are defined to further interpret the potential benefits of IIT and the risk of critical hypoglycaemia.

[Efficacy of a novel warming blanket: prospective randomized trial]. / Effektivität einer neuen Wärmedecke: Prospektive randomisierte Studie.

BACKGROUND: Perioperative hypothermia is a common complication of general anesthesia and occurs in up to 50 % of patients during ear, nose and throat (ENT) surgery. In this prospective, randomized controlled study the hypothesis that a new conductive warming blanket (Barrier® EasyWarm®, Mölnlycke Health Care Erkrath, Germany) is better in reducing the incidence of perioperative hypothermia in ENT surgery than insulation with a conventional hospital duvet alone was tested. MATERIALS AND METHODS: After approval of the local ethics committee and written informed consent 80 patients with a planned procedure time between 1 and 3 h were recruited. Anesthesia was induced and maintained using propofol, remifentanil and rocuronium and the core temperature was measured using an esophageal temperature probe. Patients in the study group were warmed at least 30 min prior to induction of anesthesia using the novel warming blanket (Barrier® EasyWarm®) and patients in the control group were insulated with a standard hospital duvet. Data were tested using Fisher's exact test, Student's t-test or the Mann-Whitney U-test as appropriate. Time-dependent changes in core temperature were evaluated using repeated measures analysis of variance (ANOVA) and post hoc Scheffé's test. Results are expressed as mean ± SD or as median and interquartile range (IQR) as appropriate. A p < 0.05 was considered to be statistically significant. RESULTS: The ANOVA did not identify a significantly higher core temperature in the study group at any time point. Furthermore, Fisher's exact test showed no differences in the incidence of intraoperative (12 out of 29 versus 10 out of 32 patients, p = 0.44) or postoperative hypothermia (12 out of 29 versus 9 out of 32 patients, p = 0.30) between the groups. No adverse effects were observed. CONCLUSIONS: In the studied patient group the new conductive warming blanket (Barrier® EasyWarm®) showed no superiority compared to conventional thermal insulation alone.

Comparison of forced-air warming and resistive heating.

BACKGROUND: Perioperative hypothermia is common during anesthesia and surgery and is accompanied by several complications. Forced-air warming is recognized as an effective procedure to prevent hypothermia. The aim of this study was to compare a resistive heating device with a forced-air warming device. METHODS: Prospective randomized trial. SETTING: heat transfer laboratory of a University hospital. PARTICIPANTS: six healthy volunteers. INTERVENTIONS: warming with a forced-air warming device (BairHugger 505 and Upper Body Blanket 522; Arizant Healthcare Inc., Eden Prairie, MN, USA) or a resistive heating device (Geratherm Adult system; Geratherm Medical AG, Geschwenda, Germany). MEASURES: heat transfer was measured with 11 calibrated heat flux transducers on the upper body. Additionally, blanket and skin temperatures were measured. The t-test for matched pairs was used for statistical evaluation. RESULTS: Skin temperature under the covered surface was not statistically different between the two groups (37.3+/-0.2 degrees C in the forced-air warming group and 37.8+/-0.2 degrees C in the resistive heating group). In contrast, blanket temperature (40.3+/-0.6 degrees C vs 38.1+/-0.4 degrees C, P=0.002) and heat transfer (13.2+/-3.6 W vs 7.8+/-1.9 W, P=0.048) were significantly higher in the resistive heating group. CONCLUSION: Heat transfer in the resistive heating system was significantly greater than that of the forced-air warming system.

Changes of jugular venous blood temperature associated with measurements of cerebral blood flow using the transcerebral double-indicator dilution technique.

BACKGROUND AND OBJECTIVE: The transcerebral double-indicator dilution technique is a recently developed method to measure global cerebral blood flow at bedside. It is based on bolus injection of ice-cold indocyanine green dye and simultaneous recording of resulting thermo- and dye-dilution curves in the aorta and the jugular bulb. However, with this method 40 mL of ice-cold solution is administered as a bolus. Therefore, this prospective clinical study was performed to elucidate the effects of repeated administration of indicator on absolute blood temperature and on cerebral blood flow and metabolism. METHODS: The investigation was performed in nine male patients scheduled for elective coronary artery bypass grafting. Absolute blood temperature was measured in the jugular bulb and in the aorta before and after repeated measurements using the transcerebral double-indicator dilution technique. RESULTS: During the investigated time course, the blood temperature in the jugular bulb, compared to the aorta, was significantly higher with a mean difference of 0.21 degrees C. The administration of an ice-cold bolus reduced the mean blood temperature by 0.06 degrees C in the jugular bulb as well as in the aorta. After the transcerebral double-indicator dilution measurements a temperature recovery to baseline conditions was not observed during the investigated time period. Cerebral blood flow and cerebral metabolism did not change during the investigated time period. CONCLUSIONS: Repeated measurements with the transcerebral double-indicator dilution technique do not affect absolute jugular bulb blood temperatures negatively. Global cerebral blood flow and metabolism measurements remain unaltered. However, accuracy and resolution of this technique is not high enough to detect the effect of minor changes of physiological variables.

Construction and evaluation of a manikin for perioperative heat exchange.

BACKGROUND: During surgery hypothermia can be avoided only if the heat exchange between the body surface and the environment can be controlled. To allow a systematic analysis of this heat exchange, we constructed and evaluated a copper manikin of the human body. METHODS: The manikin consists of six tubes (head, trunk, two arms and two legs) painted matt-black to simulate the emissivity of the human skin. Hot-water mattresses are bonded to the inner surface of the copper tubes to set the surface temperature. Calibrated heat flux transducers were placed on the following points to determine the heat exchange coefficient for radiation and convection (hRC) of the manikin: Forehead, chest, abdomen, upper arm, forearm, dorsal hand, anterior thigh, anterior leg and foot. Room temperature was set to 22 degrees C. Surface temperature of the manikin was set between 22 degrees C and 38 degrees C. The hRC was determined by linear regression analysis as the slope of the temperature gradient between the manikin and the room versus the measured heat flux. Subsequently we studied five minimally clothed volunteers in a climate chamber. Initial chamber temperature was set to 29 degrees C and was lowered slowly to 12 degrees C. The hRC was determined as described above for each volunteer. RESULTS: The hRC of the manikin was 11.0 W m(-2) degrees C(-1) and hRC of the volunteers was 10.8 W m(-2) degrees C(-1). CONCLUSION: The excellent correlation of hRC between the volunteers and the manikin will allow the manikin to be used for standardised studies of perioperative heat exchange.

In vitro validation of a metabolic monitor for gas exchange measurements in ventilated neonates.

OBJECTIVE: To evaluate the Datex Deltatrac II for measurements in neonates requiring mechanical ventilation. DESIGN: Prospective laboratory evaluation, using a ventilated lung model and gas injection. During simulation of 79 neonatal respiratory settings, assessment of oxygen consumption (VO2), carbon dioxide production (VCO2) and respiratory quotient (RQ) was compared to a reference method (mass spectrometry, wet gas spirometry) using the statistical method of Bland and Altman. INTERVENTIONS: Respiratory variables, which may influence the accuracy and precision of gas exchange measurements, were varied within the following ranges: inspired oxygen fraction (FIO2): 0.21-0.8, expired carbon dioxide fraction (FECO2) and inspiratory-expiratory oxygen fraction (DFO2): 0.0032-0.0256, expiratory flow rate: 1.0-2.5 l/min, inspiratory pressure: 10-55 mbar, respiratory rate 25-60/min, constant RQ of 1. This resulted in 79 tests with VCO2 and VO2 ranging from 8-64 ml/min. MEASUREMENTS AND RESULTS: The coefficient of repeatability for ten single subsequent Deltatrac measurements was 8.09 ml/min for VO2 and 9.17 ml/min for VCO2 compared to 2.02 ml/min and 0.90 ml/min for VO2 and VCO2 with repeated reference measurements. The coefficient of repeatability of the Deltatrac measurements improved considerably when means of subsequent 5 min intervals were compared: 0.68 ml/min for VO2 and 0.28 ml/ min for VCO2. The difference between the two methods (Deltatrac-reference) was -3.8 % (2 s: 11.4%) for VO2, 13.2% (2s: 7.9%) for VCO2 and 17.6% (2s: 16.7%) for RQ. The agreement between methods deteriorated with smaller (FECO2) or DFO2 and increasing FIO2. CONCLUSIONS: Considering limits of agreement of less than +/- 20% as clinically acceptable, results for VO2 assessment indicate acceptable accuracy and precision whereas VCO2 and RQ assessments exceed this limit. Limited accuracy and precision result from detection of CO2 following dilution of expiratory gases and increased sensitivity to error propagation by Haldane equations due to the small differences between inspiratory and expiratory gas fractions.

Perforant path lesion induces up-regulation of stathmin messenger RNA, but not SCG10 messenger RNA, in the adult rat hippocampus.

In this study, we performed in situ hybridization analysis of the expression pattern of two growth-associated proteins, stathmin and SCG10, in the hippocampus after unilateral lesion of the perforant pathway, the main excitatory input from the entorhinal cortex to the hippocampus. Stathmin is one of the major neural-enriched cytosolic phosphoproteins and a potential target of cyclic-AMP-dependent kinases [Jin L. W. et al. (1996) Neurobiol. Aging 17, 331-341; Leighton I. A. et al. (1993) Molec. Cell Biochem. 127/128, 151-156]. Three days after the lesion, stathmin messenger RNA was up-regulated ipsilaterally in the hilus, in the granule cell layer of the dentate gyrus and in the pyramidal cell layer of the CA1 region. Simultaneously, the hilar region of the contralateral dentate gyrus showed an increased stathmin messenger RNA expression. This altered expression pattern was observed until 15 days after lesion. Stathmin messenger RNA expression returned to a normal level until 21 days after lesion in all regions analysed. SCG10, a membrane-bound neuronal growth-associated protein belonging to the SCG10/stathmin gene family, did not show any alteration of messenger RNA expression after perforant path lesion. The temporal changes of stathmin messenger RNA expression in the ipsilateral hippocampus correspond well to the process of reactive synaptogenesis. The enhanced messenger RNA expression in the hilar region of the contralateral dentate gyrus might suggest a role in neurite elongation, since this region is the origin of commissural fibres involved in the sprouting response in the deafferented hippocampus. The present study provides evidence that the induction of specific growth-associated proteins is differentially regulated in the hippocampus.

[Accuracy of intraoperative urinary bladder temperature monitoring during intra-abdominal operations]. / Genauigkeit der Blasentemperaturmessung bei intraabdominellen Eingriffen.

OBJECTIVE: This study investigates whether the site of abdominal surgery or the urine flow rate affects the accuracy of urinary bladder temperature monitoring. METHODS: After approval by the local ethics committee we studied 7 patients during upper abdominal and 10 patients during lower abdominal surgery. Temperatures were recorded with a Hi-Lo Temp Esophageal-Stethoscope (Mallinckrodt Medical) and a Foley Catheter Temperature Sensor FC400-18 (Respiratory Support Products, Mallinckrodt Medical). Each probe and its recording unit were calibrated over a range of 30-40 degrees C against a reference quartz thermometer (Hewlett Packard Model 2801 A) in a water bath before the investigation. Urine flow rate was measured using a urometer. Temperatures and urine flow rate were recorded every 30 min. Agreement between the methods of measurement was assessed as described by Bland and Altman. RESULTS: 124 measuring points could be analyzed. Bladder temperature had a bias (B) of -0.06 degree C compared to oesophageal temperature. Limits of agreement (LOA; +/- 2 s) were +/- 0.68 degree C. In upper abdominal surgery (B: 0.02 degree C; LOA: +/- 0.42 degree C) a higher precision of oesophageal temperature estimation could be demonstrated compared to lower abdominal surgery (B: -0.14 degree C; LOA: +/- 0.82 degree C). Lower urine flow rates generally increased the limits of agreement. Regarding lower abdominal surgery the bias additionally increased to -0.22 degree C. CONCLUSION: Urinary bladder temperature recording is a clinically acceptable method to measure core temperature during abdominal surgery. The accuracy during lower abdominal surgery is decreased compared to upper abdominal surgery, especially in case of a urine flow rate below 250 ml/h.

[Value of reflecting disposable insulation (Thermodrape) in preventing perioperative hypothermia]. / Stellenwert eines reflektierenden Isolationsmaterials (Thermadrape) zur Verhinderung intraoperativer Hypothermie.

OBJECTIVE: The aim of the study was to evaluate the value of reflecting disposable insulation for the prevention of perioperative hypothermia. METHODS: After approval by the local ethics committee 36 patients undergoing long lasting urological intraabdominal surgery were studied. Anaesthesia was performed using etomidate, fentanyl, midazolam, pancuronium and succinylcholine. Patients were randomly assigned to 4 groups. These groups were treated as follows: Gr. 1: Infusion warmer (Hotline HL-90 with System L-70, Level 1 Technologies Inc., Marshfield, USA) and standard O.R. draping with two layers of cotton drapes. Gr. 2: Infusion warmer and reflecting disposable insulation (Thermadrape, O.R. Concepts Inc., Roanoke, USA) covering the legs, upper body, arms and head. Gr. 3: Infusion warmer and convective air warming with upper body blanket (WarmTouch, Mallinckrodt Medical, Hennef/Sieg, Germany). Gr. 4: Infusion warmer, convective air warming and reflecting disposable insulation. RESULTS: After 2 hours of surgery patients of groups 1 and 2 became hypothermic with core temperatures of 35.1 and 35.6 degrees C respectively. No relevant difference could be found between the two groups. The combination of an infusion warmer and convective air warming was an effective method to prevent hypothermia in groups 3 and 4. After 2 hours of surgery these patients had core temperatures of 36.6 and 36.4 degrees C respectively. Reflecting disposable insulation did not improve the effect of convective air warming. CONCLUSION: Reflecting disposable insulation was insufficient in the investigated operative setting.