Ernst-Peter Horn

Physostigmine Prevents Postanesthetic Shivering As Does Meperidine or Clonidine

BackgroundPostanesthetic shivering develops in as many as one half of patients recovering from isoflurane anesthesia. Cholinergic stimulation of the hypothalamic-pituitary-adrenal axis and adrenal medulla by physostigmine enhances secretion of arginine vasopressin, epinephrine, and norepinephrine. B

Patient-controlled epidural analgesia reduces analgesic requirements compared to continuous epidural infusion after major abdominal surgery.

PurposeTo compare the quality of pain relief and incidence of side effects between 24-hr postoperative continuous epidural infusion (CEI) and subsequent patient-controlled epidural analgesia (PCEA) with different analgesics after major abdominal surgery.MethodsTwenty-eight women undergoing extended gynecological tumour surgery received postoperative CEI with 0.15 ml·kg−1hr−10.2% ropivacaine (R:n = 14) or 0.125% bupivacaine plus 0.5 μg · mL−1 sufentanil (BS:n = 14) during 24 postoperative hours. Twenty-four hours later, postoperative pain management was switched to PCEA without background infusion and 5 mL single bolus application of R or BS every 20 min at most. Visual analogue scales (VAS; 1–100 mm) were assessed by patients at rest and on coughing after 24 hr of CEI and PCEA. Side effects, doses of local anesthetics and opioids were recorded and plasma concentrations of total and unbound ropivacaine and bupivacaine were measured.ResultsPatients required lower doses of each respective analgesic medication with PCEA (R: 108 ± 30 mL; BS: 110 ± 28 mL) than with CEI (R: 234 ± 40; BS: 260 ± 45;P < 0.01). Ropivacaine plasma concentrations were lower 24 hr after PCEA when compared with CEI (P < 0.01). No patient after PCEA but two after CEI (n = 4; NS) presented motor block. PCEA with R provided better postoperative pain relief than CEI (37 ± 32vs 59 ±27,P < 0.05). No difference in parenteral opioid rescue medication between CEI and PCEA was seen.ConclusionPCEA in comparison to preceding CEI provides equivalent analgesia with lower local anesthetic doses and plasma levels, and without motor blocking side effects, irrespective of the applied drug regimen.RésuméObjectifComparer la qualité de l’analgésie et l’incidence d’effets secondaires entre une perfusion postopératoire péridurale continue (PPC) de 24 h et une analgésie péridurale auto-contrôlée (APAC) ultérieure, réalisée avec différents analgésiques après une intervention chirurgicale majeure.MéthodeVingt-huit femmes, devant subir l’ablation élargie d’une tumeur gynécologique, ont reçu une PPC postopératoire avec 0,15 mL · kg−1hr−1 de ropivacaine à 0,2 % (R: n = 14) ou de bupivacaïne à 0,125% plus 0,5 μg · mL−1 de sufentanil (BS:n = 14) pendant 24 h après l’opération. La PPC a été ensuite remplacée par une APAC, sans perfusion d’appoint, et avec l’application d’un unique bolus de 5 mL de R ou de BS toutes les 20 min au plus. L’échelle visuelle analogique (EVA; 1–100 mm) a été évaluée par les patientes au repos et pendant la toux après 24 h de PPC et d’APAC. Les effets secondaires, les doses d’anesthésiques locaux et d’opidides ont été notées et les concentrations plasmatiques de ropivacaïne et de bupivacaïne totales et libres, mesurées.RésultatsLes patientes ont demandé de plus faibles doses de chacun des analgésiques avec l’APAC (R: 108 ± 30 mL; BS: 110 ± 28 mL) qu’avec la PPC (R: 234 ± 40; BS: 260 ± 45; P < 0,01). Les concentrations plasmatiques de ropivacaïne étaient plus faibles 24 h après l’APAC, comparée à la PPC (P < 0,01). Aucune patiente n’a présenté de bloc moteur après l’administration d’APAC, mais deux après la PPC (n = 4; NS). L’APAC avec R s’est révélée meilleure que la PPC comme analgésique postopératoire (31 ± 32 vs 59 ± 27, P < 0,05). Nous n’avons observé aucune différence de médication de secours, avec opioïde parentéral, entre la PPC et l’APAC.ConclusionLAPAC, comparée à la PPC qui a précédé, fournit une analgésie équivalente pour des doses d’anesthésique local et des niveaux plasmatiques plus faibles et sans les effets secondaires de bloc moteur, peu importe le régime médicamenteux appliqué.

Bovine hemoglobin increases skeletal muscle oxygenation during 95% artificial arterial stenosis

BACKGROUND This study investigates the effect of a stroma-free ultrapurified bovine hemoglobin solution (HBOC) on skeletal muscle tissue oxygenation in comparison with hetastarch during nearly complete arterial stenosis. METHODS Fourteen foxhounds were intravenously anesthetized and mechanically ventilated with 30% oxygen in air. Catheters were inserted into the right femoral artery and vein for measurements of hemodynamic parameters and blood gas sampling. Arterial blood flow of the left popliteal artery was measured by means of an electromagnetic flow probe. Skeletal muscle tissue oxygen tension (tpO2) was measured in the left gastrocnemius muscle by using a stepwise driven polarographic needle probe creating histograms from 200 single tpO2 measurements. After isovolemic hemodilution with Ringers lactate solution to a hematocrit of 25%, a 95% artificial stenosis of the popliteal artery was established. The animals then randomly received two applications of either 50 ml HBOC (molecular weight, 32,000 to 500,000; hemoglobin, 13 +/- 1 gm/dl-1) or 200 ml 6% hetastarch 200,000/0.5. Variables were measured at baseline, after hemodilution, 30 minutes after stenosis, and 15 minutes after two applications of the respective compound. RESULTS Demographic data, muscle temperature, and arterial blood gases did not differ between groups. With the exception of higher mean arterial and mean pulmonary artery pressures in HBOC-treated animals, hemodynamics did not differ between groups. In both groups oxygen delivery and oxygen consumption of the muscle decreased in parallel to the decreasing blood flow during arterial stenosis. In contrast, oxygen extraction ratio increased after infusion of HBOC and was higher after the second application when compared with hetastarch-treated animals (p < 0.05). During stenosis tpO2 was decreased in both groups when compared with baseline (p < 0.001). Mean tpO2 remained at decreased levels after administration of hetastarch but increased to nearly baseline values after HBOC treatment (p < 0.001). CONCLUSIONS The data suggest that increased oxygen extraction in the HBOC group is associated with improved skeletal muscle tissue oxygenation during severe arterial stenosis.

Wound Infiltration and Drain Lavage with Ropivacaine After Major Shoulder Surgery

UNLABELLED Subcutaneous infiltration and wound lavage with ropivacaine is an alternative to opioids after major shoulder surgery. However, the efficacy and potential toxicity of this method remain unclear. We therefore evaluated plasma ropivacaine concentrations after shoulder infiltration and wound lavage. We subsequently quantified the efficacy of two ropivacaine concentrations. Patients undergoing major shoulder surgery were anesthetized with alfentanil and propofol. The initial patients (n = 18) received ropivacaine 7.5 mg/mL and ropivacaine plasma concentrations were measured in 15-min intervals. The subsequent 45 patients were randomly assigned to: 1) isotonic saline, 2) 3.75 mg/mL ropivacaine, or 3) 7.5 mg/mL ropivacaine. Ten milliliters of each solution was administered subcutaneously and 20 mL was injected into the wound drain which was clamped for 10 min. Supplemental postoperative pain relief was provided by patient-controlled anesthesia using the opioid piritramid (3.5-mg boluses, 6-min lock-out). Postoperative pain scores were recorded on a 100-mm visual analog scale for 4 h in the initial patients and for 10 h in the second part of the study. Unbound ropivacaine plasma concentrations peaked after 15 min at 0.08+/-0.09 microg/mL; the maximum was 0.30 microg/mL, compared with a toxic threshold of 0.6 microg/mL. In the second part of the study, pain scores were significantly lower after 3.75 mg/mL (20+/-15 mm) or 7.5 mg/mL (10+/-9 mm) ropivacaine than saline (35+/-10 mm). Piritramid requirements differed significantly in the three groups, being highest with saline and lowest with ropivacaine 7.5 mg/mL. We conclude that wound infiltration and lavage with 30 mL ropivacaine 7.5 mg/mL after major shoulder surgery resulted in very low pain scores and opioid requirement. IMPLICATIONS Wound infiltration and lavage with 30 mL ropivacaine 7.5 mg/mL after major shoulder surgery resulted in very low pain scores and opioid requirement.

Präoperative Hämodilution mit bovinem Hämoglobin Akute hämodynamische Auswirkungen bei Patienten in der Leberchirurgie

ZusammenfassungHämoglobinlösungen sind kolloidale Volumenersatzpräparate, die Sauerstoff transportieren und damit eine Alternative zur homologen Transfusion von Erythrozyten darstellen können. Ziel der vorliegenden klinischen Studie war es, ein polymerisiertes ultragereinigtes Rinderhämoglobin (HBOC-201) im Vergleich zu Hydroxyäthylstärke (HES) auf Veränderungen der Hämodynamik und der O2-Transportparameter während und nach Hämodilution zu untersuchen. Material und Methoden: Nach Zustimmung durch die Ethikkommission wurden 12 Patienten (6 m. u. 6 w., Alter 59±10 J., ASA I–II, die sich einer Leberteilresektion unterziehen mußten, randomisiert auf 2 Gruppen verteilt. In Gruppe 1 erhielten die Patienten im Anschluß an eine präoperative Eigenblutspende von 1 l eine Infusion von 3 ml·kg−1 6% HES 70000/0,5 über 30 min sowie 2 l Ringerlaktat. Patienten der Gruppe 2 erhielten 2 l Ringerlaktat und über 30 min 0,4 g·kg−1 HBOC-201. Blutgasanalysen, Hämodynamik und Parameter des O2-Transports wurden vor und nach Eigenblutspende, während und nach Infusion, bei Operationsbeginn und auf der Intensivstation gemessen. Ergebnisse: Der arterielle Mitteldruck stieg unter Infusion von HBOC-201 im Gegensatz zu HES um maximal 18% gegenüber der Ausgangsmessung an. Während der pulmonale Gefäßwiderstand in der HBOC-201-Gruppe einen Trend zu höheren Werten als in der HES-Gruppe zeigte, stieg der systemische Gefäßwiderstand unter Infusion von HBOC-201 im Vergleich zum Ausgangswert um maximal 42% und war doppelt so hoch wie in der HES-Gruppe. Der Cardiac-Index lag in der HBOC-201-Gruppe unter den Werten der HES-Gruppe. Gemischt-venöse O2-Konzentrationen und -Sättigung sowie das errechnete O2-Angebot waren während und nach HBOC-201 Applikation niedriger als in der HES-Gruppe, während die O2-Extraktion nach Infusion von HBOC-201 höher war als nach HES. Die maximale Plasmakonzentration von HBOC-201 betrug 1,0±0,2 g·dl−1, die intravasale Halbwertszeit im Mittel 8,5 h. Im Urin war kein freies Hämoglobin nachweisbar. Schlußfolgerung. Die Ergebnisse zeigen bei guter Verträglichkeit der HBOC-201-Lösung einen vasokonstriktorischen Nebeneffekt, der zu einer Steigerung insbesondere des systemischen Gefäßwiderstands führt.AbstractHaemoglobin solutions can be an alternative to allogeneic red-cell transfusions because they combine colloid osmotic with oxygen transport properties. Since severe toxic side effects have been overcome by ultrapurification, clinical interest has been focused on haemodynamics changes during application of haemoglobin preparations. The present clinical study examines changes of haemodynamic and oxygen transport parameters during and after haemodilution with ultrapurified polymerized bovine haemoglobin (HBOC-201) in comparison to hydroxyethyl starch (HES). Methods: After approval of the Ethics Committee, 12 patients (6 males and 6 females, mean age 59±10 years, ASA 1-2) undergoing elective liver resection were randomly allocated to receive either 3 ml·kg−1 6% HES 70000/0.5 (group 1) or 0.4 g· kg−1 HBOC-201 (group 2) within 30 min following autologous blood donation of 1 l and substitution with 2 l Ringer’s lactate. Measurements of blood gases, haemodynamics, and oxygen transport parameters were performed after induction of general anaesthesia, prior to and after blood donation, during and after infusion, at the beginning of surgery, and in the intensive care unit. Results: Demographic characteristics did not differ between groups. In contrast to the HES group, mean arterial pressure increased by 18% over baseline measurements in group 2. While pulmonary vascular resistance showed a trend to higher values in group 2, systemic vascular resistance increased to a maximum of 42% over baseline in group 2 and was twice as high as in the HES group. The cardiac index was lower in the HBOC-201 group than in the HES group. During and after HBOC-201 infusion, mixed-venous oxygen saturation and content and calculated oxygen delivery were lower in group 2 in comparison to group 1, while the oxygen extraction ratio was higher in group 2. Free haemoglobin reached a maximal concentration of 1.0±0.2 g·dl−1 30 min after the HBOC-201 infusion was started, but was not detectable in urine over time. The mean intravascular half-life of HBOC-201 was 8.5 h. Conclusions: Patients did not show any severe complications during and after infusion of HBOC-201. However, vasoconstrictive side effects resulted in increased systemic but not pulmonary resistance. Ongoing studies with higher doses of HBOC-201 applied in a larger number of patients will probably reveal potential clinical consequences of the demonstrated haemodynamic changes.

Preventing inadvertent perioperative hypothermia.

BACKGROUND 25-90% of all patients undergoing elective surgery suffer from inadvertent postoperative hypothermia, i.e., a core body temperature below 36°C. Compared to normothermic patients, these patients have more frequent wound infections (relative risk [RR] 3.25, 95% confidence interval [CI] 1.35-7.84), cardiac complications (RR 4.49, 95% CI 1.00-20.16), and blood transfusions (RR 1.33, 95% CI 1.06-1.66). Hypothermic patients feel uncomfortable, and shivering raises oxygen consumption by about 40%. METHODS This guideline is based on a systematic review of the literature up to and including October 2012 and a further one from November 2012 to August 2014. The recommendations were developed and agreed upon by representatives of five medical specialty societies in a structured consensus process. RESULTS The patients core temperature should be measured 1-2 hours before the start of anesthesia, and either continuously or every 15 minutes during surgery. Depending on the nature of the operation, the site of temperature measurement should be oral, naso-/oropharyngeal, esophageal, vesical, or tympanic (direct). The patient should be actively prewarmed 20-30 minutes before surgery to counteract the decline in temperature. Prewarmed patients must be actively warmed intraoperatively as well if the planned duration of anesthesia is longer than 60 minutes (without prewarming, 30 minutes). The ambient temperature in the operating room should be at least 21°C for adult patients and at least 24°C for children. Infusions and blood transfusions that are given at rates of >500 mL/h should be warmed first. Perioperatively, the largest possible area of the body surface should be thermally insulated. Emergence from general anesthesia should take place at normal body temperature. Postoperative hypothermia, if present, should be treated by the administration of convective or conductive heat until normothermia is achieved. Shivering can be treated with medications. CONCLUSION Inadvertent perioperative hypothermia can adversely affect the outcome of surgery and the patients postoperative course. It should be actively prevented.

The incidence and prevention of hypothermia in newborn bonding after cesarean delivery: a randomized controlled trial.

BACKGROUND:Little is known about thermoregulation of the newborn while bonding on the mother’s chest immediately after cesarean delivery. Newborn hypothermia is associated with serious complications and should be avoided. Therefore, we evaluated whether newborns develop hypothermia during intraoperative bonding while positioned on their mothers’ chests and investigated the effects of active cutaneous warming of the mothers and babies during a 20-minute intraoperative bonding period. METHODS:We enrolled 40 parturients scheduled for elective cesarean delivery under spinal anesthesia. Mothers and their newborns were randomized to receive either passive insulation or forced-air skin-surface warming during the surgical procedure and bonding period. The primary outcome was neonatal core temperature at the end of the bonding period. Core temperatures of the newborns were measured with a rectal probe. Body temperatures of the mothers were assessed by sublingual measurements. Skin temperatures, thermal comfort of the mothers, and perioperative shivering were evaluated. RESULTS:Without active warming from the beginning of the surgical procedure until the end of the bonding period, the mean (SD) neonatal core temperature decreased to 35.9 (0.6)°C. Seventeen of 21 (81%) newborns became hypothermic (defined as a core temperature below 36.5°C). Active skin-surface warming from the beginning of the surgical procedure until the end of the bonding period resulted in a neonatal core temperature of 37.0 (0.2)°C and a decreased incidence of hypothermia (1 of 19 (5%) newborns (P < 0.0001)). In addition, active warming increased the mean skin temperatures of the infants, maternal core and skin temperatures, maternal thermal comfort, and reduced perioperative shivering. CONCLUSIONS:Active forced-air warming of mothers and newborns immediately after cesarean delivery reduces the incidence of infant and maternal hypothermia and maternal shivering, and increases maternal comfort.

Subarachnoid Sufentanil for early postoperative pain management in orthopedic patients : A placebo-controlled, double-blind study using spinal microcatheters

BackgroundContinuous spinal anesthesia is frequently used for intraoperative anesthesia but rarely for postoperative pain management. Because even small doses of local anesthetics can be associated with motor deficits, subarachnoid opioid injection may be an alternative. MethodsEighty patients randomly received a subarachnoid injection of 10 &mgr;g sufentanil, 5 mg bupivacaine, 2.5 &mgr;g sufentanil plus 2.5 mg bupivacaine, or saline through 28-gauge spinal microcatheters for early postoperative pain relief after major lower-limb surgery (n = 20 in each group). Hemodynamic and respiratory parameters, pain scores, and motor function were monitored, and sufentanil concentrations in plasma and cerebrospinal fluid were measured. Ten additional patients received up to three repetitive injections of 10 &mgr;g sufentanil over 24 h. ResultsAll drugs provided excellent pain relief within 15 min after injection, lasting 128 ± 61 min with sufentanil, 146 ± 74 min with bupivacaine, and 167 ± 78 min with the mixture. Patients receiving bupivacaine showed the highest cephalad extension of sensory block (median, T6) and the most intense motor block, whereas patients given only sufentanil had no motor deficit. The duration of analgesia was shorter after subsequent sufentanil injection (100–115 min) than after the first injection (198 ± 70 min). Six of 50 patients with sufentanil experienced a short episode of respiratory depression within 30 min after the first injection. Cerebrospinal fluid concentrations of sufentanil peaked at 5 min after injection (183 ± 167 ng/ml) but were at the level of detection in the plasma. ConclusionsSufentanil injected through microspinal catheters provided profound pain relief without impairing motor function when compared with bupivacaine. However, close monitoring remains mandatory in this setting.

Transfusion of autologous, hydroxyethyl starch-cryopreserved red blood cells.

In this prospective, randomized study, we investigated the safety and efficacy of the transfusion of hydroxyethyl starch (HES) cryopreserved red blood cells (RBC) compared with the transfusion of liquid-stored RBC in patients undergoing major orthopedic or urologic surgery. Thirty-six patients donated autologous blood 35 +/- 6 days before elective surgery. Only the first of 3.5 +/- 1.3 donated units of RBC was randomly assigned to be stored in the liquid state at 4[degree sign]C in phosphate/adenine/guanosine/glucose/saline-Mannitol or frozen below -130[degree sign]C by means of liquid nitrogen after the addition of HES (molecular weight 200,000 Dalton, degree of substitution 0.5, final concentration 11.5% wt/wt) as a cryoprotectant. After induction of anesthesia, patients donated 900 mL of autologous blood before they received one unit of liquid-stored RBC in Group 1. In Group 2, one unit of cryopreserved autologous RBC was transfused after removal of the cryoprotectant HES. In Group 3, patients received one unit of cryopreserved RBC without any manipulation after thawing. Patients in Groups 1 and 2 received additional 500 mL of 10% HES. Hemodynamic variables, arterial blood gases, plasma hemoglobin, and arterial lactate concentrations were measured after the induction of anesthesia, after hemodilution, and at 10-min intervals after transfusion of the respective RBC concentrate over a period of 40 min. Skeletal muscle tissue oxygen tension was measured in the quadriceps muscle using an automatically stepwise-driven oxygen partial pressure electrode. We found no differences among groups concerning demographics, arterial blood gas values, and lactate concentrations and observed no adverse reactions after transfusion of the conventionally stored or cryopreserved RBC. Hemodynamic variables did not differ among groups, with the exception of an increased mean arterial blood pressure after the transfusion of cryopreserved unwashed RBC. In all groups, the skeletal muscle tissue oxygen tension remained constant after hemodilution and increased after transfusion of either washed or unwashed cryopreserved RBC. Although the free plasma hemoglobin concentration remained constant after the transfusion of liquid-stored RBC (26 +/- 8 mg/dL), the plasma hemoglobin concentration increased twofold after the transfusion of cryopreserved washed RBC (60 +/- 12 mg/dL) and threefold after transfusion of cryopreserved unwashed RBC (98 +/- 20 mg/dL). The authors conclude that transfusion of one unit of RBC after cryopreservation with HES is safe and well tolerated by patients. Intravascular volume replacement and skeletal muscle oxygenation characteristics by erythrocytes did not differ between liquid-stored and cryopreserved RBC. Implications: This study examined whether a colloid should be used to store blood. Our data suggest that the transfusion of one unit of red blood cells after cryopreservation with hydroxyethyl starch is safe and well tolerated by patients. The effects of intravascular volume replacement and skeletal muscle oxygenation provided by red blood cells after liquid storage or cryopreservation were not different. (Anesth Analg 1997;85:739-45)

Intraoperative temperature monitoring with zero heat flux technology (3M SpotOn sensor) in comparison with sublingual and nasopharyngeal temperature: An observational study.

BACKGROUND Perioperative hypothermia is common in patients undergoing general anaesthesia and is associated with important adverse events. The ‘gold standard’ for monitoring body core temperature – the pulmonary artery catheter – is invasive and unsuitable for most patients. For routine clinical practice, other sites and methods of temperature monitoring are commonly used. OBJECTIVE The aim of this study was to evaluate a new temperature sensor (3M SpotOn) using the ’zero heat flux’ method attached to the forehead, and compare it to sublingual and nasopharyngeal sensors in terms of correlation, accuracy and precision. DESIGN An observational study. SETTING University Medical Center Schleswig Holstein, Campus Kiel, Germany from October 2013 to January 2014. PATIENTS One hundred and twenty patients scheduled for elective gynaecological or trauma surgery undergoing general anaesthesia were enrolled into this study. Data of 83 patients were finally analysed. Patients with unexpected blood loss, haemodynamic instability determined by the need for continuous norepinephrine infusion and/or need for postoperative ventilation were excluded from this study. INTERVENTION Temperature monitoring was established after induction of anaesthesia with sublingual and nasopharyngeal probes, and the SpotOn sensor. MAIN OUTCOME MEASURES Body temperature was measured 15, 45 and 75 min after induction of anaesthesia from sublingual and nasopharyngeal probes and the 3M SpotOn sensor at precisely the same moment. RESULTS Analysis of 83 data sets revealed that 3M SpotOn temperatures were almost identical with nasopharyngeal temperatures (mean difference 0.07°C; P = 0.1424) and slightly lower than sublingual temperatures by 0.35°C (P < 0.0001). Coefficients of determination (r) for both methods were between 0.87 (SpotOn vs. nasopharyngeal measurement) and 0.77 (SpotOn vs. sublingual measurement). Bland–Altman analysis revealed a bias (SD) between 0.07°C (0.21) (SpotOn vs. nasopharyngeal) and −0.35°C (0.29) (SpotOn vs. sublingual measurement). CONCLUSION With respect to correlation, accuracy and precision, the 3M SpotOn sensor provides a good measurement of body temperature in comparison to the nasopharyngeal probe and an acceptable measurement in comparison with sublingual thermometry. It is adequate for clinical use. TRIAL REGISTRATION Clinicaltrials.gov identifier: NCT02031159