J. Vettermann

DROPERIDOL CAUSES A DOSE-DEPENDENT PROLONGATION OF THE QT INTERVAL

To further investigate possible prolongation of the frequency-corrected QT interval (QTc interval) after administration of droperidol (DRO), we studied 40 surgical patients who were randomly assigned to one of three groups, receiving an intravenous (IV) injection of either 0.1 mg/kg (Group 1, n = 10), 0.175 mg/kg (Group 2, n = 10), or 0.25 mg/kg (Group 3, n = 20) of DRO at induction of anesthesia. The QTc interval, heart rate, and arterial pressure were registered before and 1, 2, 3, 4, 5, 7.5, and 10 min after the respective dose injection. Significant prolongations of the median QTc interval were found in patients from all groups, ranging from 37 ms (8.0%) in Group 1, to 44 ms (10.6%) in Group 2, to 59 ms (14.9%) in Group 3, when compared with control. The heart rate showed a significant increase in all groups. Mean arterial pressure (MAP) was slightly but significantly decreased in Groups 1 and 3. Prolongation of the QTc interval is a predictable and dose-dependent side effect after injection of high-dose DRO.

[The i-STAT analyzer. A new, hand-held device for the bedside determination of hematocrit, blood gases, and electrolytes].

ZusammenfassungZielsetzung und Methoden: In der chirurgischen Operationseinheit und Intensivstation der Universitätsklinik wurden bei 49 Patienten arterielle Blutproben entnommen und simultan mit dem i-STAT Analyzer (Kartusche EG7+) und einem Referenzgerät ausgewertet. Die Kartusche EG7+ ermittelt die Parameter ionisiertes Kalzium, Kalium, Natrium, pH, pCO2, pO2 und Hämatokrit. HCO3, BE, SO2 und Hb werden aus diesen Daten errechnet. Der Hkt bzw. das Hb kann mit der speziellen Anpassung (HLM) für erniedrigtes Serumprotein z.B. während kardiopulmonalem Bypass unter Herz-Lungenmaschine (HLM) korrigiert werden. Ergebnisse: Mit dem Referenzgerät ABL 615 und EML 100 wurden die Korrelationen (r) für ionisiertes Kalzium (r=0,85), Kalium (r=1,0), Natrium (r=0,86), pH (r=0,99), pCO2 (r=0,98), pO2 (r=0,99), HCO3 (r=0,93), BE (r=0,93), Hb (r=0,46), Hb/HLM (r=0,95), Hkt (r=0,81) und Hkt/HLM (r=0,98) ermittelt. Die 95% Binominalverteilung der Differenzen lagen beim Kalium, Natrium, pCO2, pO2 und Hkt/HLM innerhalb der Vorgaben zur Qualitätssicherung der Bundesärztekammer. Die Meßwerte für ionisiertes Kalzium, pH und Hb/HLM lagen zwar außerhalb der empfohlenen Toleranzen der BÄK, sind aber für den klinischen Gebrauch akzeptabel. Im anästhesiologischen Bereich sollte zur Hkt- oder Hb Bestimmung immer die „HLM” Anpassung für erniedrigtes Serumprotein programmiert werden. Zusammenfassung: Der einfache Gebrauch, die Transportierbarkeit und eine Analysezeit der Blutproben von ca. 2,5 min sowie die Wirtschaftlichkeit bei geringstem Wartungsaufwand prädestinieren dieses Gerät auch für innerklinische Notfälle, z.B. im Schockraum oder auf Normalstation.AbstractExact and quick measurements of basic laboratory parameters are important in selected patients in the perioperative period. Depending on the capabilities of a hospital’s central laboratory, the anaesthesiologist may only obtain such laboratory tests after unacceptable delays. This problem may be overcome by a new bedside measurement device that has become available from i-STAT Corporation, Princeton, USA. The hand-held, battery-driven analyser accepts blood specimens that are injected into a disposable cartridge (EG7+) and measures acidity, blood gas tensions, haematocrit, and electrolytes. The aim of this study was to determine the accuracy of such measurements by comparing them with measurements obtained by conventional laboratory test methods. Methods: Heparinised arterial blood specimens were collected in duplicate from 49 surgical patients. Measurements of ionised calcium (Ca), sodium (Na), potassium (K), pH, pCO2, pO2, base excess (BE), haematocrit (Hct), and haemoglobin (Hb) obtained by the i-STAT analyser were compared with measurements from the calibrated analysers ABL 615 and EML 100 (Radiometer, Copenhagen). Because the i-STAT analyser calculates the Hb concentration from a conductometrically measured Hct, 19 blood specimens were centrifuged in order to compare test results with conventionally obtained Hct and Hb values. As the Hct test sensitivity with the i-STAT changes with diluted blood due to its low albumin concentration, Hct and Hb measurements during cardio-pulmonary bypass (CPB) must be corrected by activating an analyser-implemented correction algorithm (Hct/CPB and Hb/CPB). Correlation analysis was performed between conventional measurements and i-STAT values (Ca, Na, K, Hct, pCO2, pO2), between values that the i-STAT analyser derives (Hb, HCO3, BE) and conventionally obtained results, and between normal and CPB-corrected Hct and Hb values. Accuracy was judged according to the national quality standard, whic h requires test results to lie within the 95% confidence interval of conventional tests. Results: Each blood specimen was analysed: erroneous results or technical failures did not occur. Measurement of one set of i-STAT values required 2.5 min. Correlation coefficients (r) between conventional and i-STAT results were: 0.85 for CA, 1.0 for K; 0.86 for Na; 0.99 for pH; 0.98 for pCO2; 0.99 for pO2; 0.93 for HCO3; 0.93 for BE; 0.46 for Hb values not corrected for CPB and 0.95 for CPB-corrected Hb; and 0.74 for Hct values not corrected for CPB and 0.98 for CPB-corrected Hct. The correlation coefficient for Hct between centrifuged and CPB-uncorrected i-STAT values was 0.81 and that for CPB-corrected values was 0.98. National accuracy requirements were not met for tests of: Ca (by 0.02 mmol/l); pH (by 0.01); pO2 including hyperoxic values (by 26.7 mmHg, but were met for pO2 values <200 mmHg); Hb (by 1.6 g/dl); Hb/CPB (by 0.8 g/dl); and Hct (by 6.5%, but were met for Hct/CPB values). All other tests fulfilled the required standards. Conclusion: This analyser is easy to use, reliable, and portable, and therefore suitable for the operating room, for analyses during emergencies, on peripheral wards, for preclinical screening, or at times when availability of lab tests is time-consuming or limited. The test accuracy for electrolytes, blood gases, and Hb is high enough to justify routine use of the i-STAT analyser in clinical practice. That the nationally required quality standards for Ca, pH, and Hb were not met is not of importance because the measured deviation was too small to have clinical relevance. When analysing diluted blood with a low Hct and low oncotic pressure, it is important to activate the analyser’s correction algorithm „CPB”, because the obtained results will then comply with the required accuracy.

Der i-STAT Analyzer : Ein neues, tragbares Gerät zur Bedsidebestimmung des Hämatokrits, der Blutgase und Elektrolyte

ZusammenfassungZielsetzung und Methoden: In der chirurgischen Operationseinheit und Intensivstation der Universitätsklinik wurden bei 49 Patienten arterielle Blutproben entnommen und simultan mit dem i-STAT Analyzer (Kartusche EG7+) und einem Referenzgerät ausgewertet. Die Kartusche EG7+ ermittelt die Parameter ionisiertes Kalzium, Kalium, Natrium, pH, pCO2, pO2 und Hämatokrit. HCO3, BE, SO2 und Hb werden aus diesen Daten errechnet. Der Hkt bzw. das Hb kann mit der speziellen Anpassung (HLM) für erniedrigtes Serumprotein z.B. während kardiopulmonalem Bypass unter Herz-Lungenmaschine (HLM) korrigiert werden. Ergebnisse: Mit dem Referenzgerät ABL 615 und EML 100 wurden die Korrelationen (r) für ionisiertes Kalzium (r=0,85), Kalium (r=1,0), Natrium (r=0,86), pH (r=0,99), pCO2 (r=0,98), pO2 (r=0,99), HCO3 (r=0,93), BE (r=0,93), Hb (r=0,46), Hb/HLM (r=0,95), Hkt (r=0,81) und Hkt/HLM (r=0,98) ermittelt. Die 95% Binominalverteilung der Differenzen lagen beim Kalium, Natrium, pCO2, pO2 und Hkt/HLM innerhalb der Vorgaben zur Qualitätssicherung der Bundesärztekammer. Die Meßwerte für ionisiertes Kalzium, pH und Hb/HLM lagen zwar außerhalb der empfohlenen Toleranzen der BÄK, sind aber für den klinischen Gebrauch akzeptabel. Im anästhesiologischen Bereich sollte zur Hkt- oder Hb Bestimmung immer die „HLM” Anpassung für erniedrigtes Serumprotein programmiert werden. Zusammenfassung: Der einfache Gebrauch, die Transportierbarkeit und eine Analysezeit der Blutproben von ca. 2,5 min sowie die Wirtschaftlichkeit bei geringstem Wartungsaufwand prädestinieren dieses Gerät auch für innerklinische Notfälle, z.B. im Schockraum oder auf Normalstation.AbstractExact and quick measurements of basic laboratory parameters are important in selected patients in the perioperative period. Depending on the capabilities of a hospital’s central laboratory, the anaesthesiologist may only obtain such laboratory tests after unacceptable delays. This problem may be overcome by a new bedside measurement device that has become available from i-STAT Corporation, Princeton, USA. The hand-held, battery-driven analyser accepts blood specimens that are injected into a disposable cartridge (EG7+) and measures acidity, blood gas tensions, haematocrit, and electrolytes. The aim of this study was to determine the accuracy of such measurements by comparing them with measurements obtained by conventional laboratory test methods. Methods: Heparinised arterial blood specimens were collected in duplicate from 49 surgical patients. Measurements of ionised calcium (Ca), sodium (Na), potassium (K), pH, pCO2, pO2, base excess (BE), haematocrit (Hct), and haemoglobin (Hb) obtained by the i-STAT analyser were compared with measurements from the calibrated analysers ABL 615 and EML 100 (Radiometer, Copenhagen). Because the i-STAT analyser calculates the Hb concentration from a conductometrically measured Hct, 19 blood specimens were centrifuged in order to compare test results with conventionally obtained Hct and Hb values. As the Hct test sensitivity with the i-STAT changes with diluted blood due to its low albumin concentration, Hct and Hb measurements during cardio-pulmonary bypass (CPB) must be corrected by activating an analyser-implemented correction algorithm (Hct/CPB and Hb/CPB). Correlation analysis was performed between conventional measurements and i-STAT values (Ca, Na, K, Hct, pCO2, pO2), between values that the i-STAT analyser derives (Hb, HCO3, BE) and conventionally obtained results, and between normal and CPB-corrected Hct and Hb values. Accuracy was judged according to the national quality standard, whic h requires test results to lie within the 95% confidence interval of conventional tests. Results: Each blood specimen was analysed: erroneous results or technical failures did not occur. Measurement of one set of i-STAT values required 2.5 min. Correlation coefficients (r) between conventional and i-STAT results were: 0.85 for CA, 1.0 for K; 0.86 for Na; 0.99 for pH; 0.98 for pCO2; 0.99 for pO2; 0.93 for HCO3; 0.93 for BE; 0.46 for Hb values not corrected for CPB and 0.95 for CPB-corrected Hb; and 0.74 for Hct values not corrected for CPB and 0.98 for CPB-corrected Hct. The correlation coefficient for Hct between centrifuged and CPB-uncorrected i-STAT values was 0.81 and that for CPB-corrected values was 0.98. National accuracy requirements were not met for tests of: Ca (by 0.02 mmol/l); pH (by 0.01); pO2 including hyperoxic values (by 26.7 mmHg, but were met for pO2 values <200 mmHg); Hb (by 1.6 g/dl); Hb/CPB (by 0.8 g/dl); and Hct (by 6.5%, but were met for Hct/CPB values). All other tests fulfilled the required standards. Conclusion: This analyser is easy to use, reliable, and portable, and therefore suitable for the operating room, for analyses during emergencies, on peripheral wards, for preclinical screening, or at times when availability of lab tests is time-consuming or limited. The test accuracy for electrolytes, blood gases, and Hb is high enough to justify routine use of the i-STAT analyser in clinical practice. That the nationally required quality standards for Ca, pH, and Hb were not met is not of importance because the measured deviation was too small to have clinical relevance. When analysing diluted blood with a low Hct and low oncotic pressure, it is important to activate the analyser’s correction algorithm „CPB”, because the obtained results will then comply with the required accuracy.

Intravenöse Sedierung von spontanatmenden Säuglingen und Kleinkindern während der Magnetresonanztomographie

ZusammenfassungEs war das Ziel der vorliegenden Untersuchung, zwei intravenöse Sedierungstechniken mit Propofol (P) oder Methohexital (M) zur elektiven Magnetresonanztomographie (MRT) bei 120 Kindern unter 6 Jahren bezüglich Sicherheit, Nebenwirkungen, Aufwachverhalten und Verlegungszeiten zu vergleichen. Jeweils 60 unprämedizierte Kinder erhielten prospektiv, randomisiert eine Einschlafdosis von M oder P und zusätzliche Injektionen bei Anzeichen unzureichender Sedierungstiefe. Herzfrequenz (HF), pulsoxymetrische Sättigung (SpO2), Atemfrequenz (AF) sowie endtidaler CO2-Partialdruck (PetCO2) wurden kontinuierlich gemessen. Bei einer Untersuchungdauer von 28,4 min (M) bzw. 28,9 min (P) betrug die durchschnittliche Einschlaf- und Gesamtdosis für Methohexital 2,3±0,7 mg/kg und 6,1 ±3,3 mg/kg und für Propofol 2,3 ±0,9 mg/kg und 5,8±2,7 mg/kg. Erniedrigungen der SpO2<90% traten nur nach der Erstinjektion mit einer Häufigkeit von 0,49% (M) bzw. 0,64% (P) aller Messungen auf. Apnoephasen >20 s wurden bei 2 Kindern jeder Gruppe, eine Erhöhung des PetCO2>48 mm Hg in 0,36% (M) bzw. 0,71% (P) aller Meßbeobachtungen registriert. Spontane Bewegungen machten bei 5% der Kinder jeder Gruppe eine Wiederholung der vorangehenden MRT-Sequenz notwendig. Aufwach- und Verlegungszeiten waren mit 0,8 min und 2,2 min unter P signifikant kürzer als unter M (1,5 min und 3,5 min; p<0,01). 10 min nach MRT-Ende waren alle Kinder gleich vigilant. Übelkeit und Erbrechen wurden weder unter M noch unter P beobachtet. Die vorgestellte intravenöse Monosedierung mit M oder P ist ein sicheres Verfahren zur Ruhigstellung von Säuglingen und Kindern zur elektiven MRT. Beide Medikamente sind gleich gut geeignet.AbstractThe purpose of the present study was to compare two sedation regimens with either propofol (P) or methohexital (M) for elective magnetic resonance imaging (MRI) in children with respect to safety, side effects, recovery, and discharge time. Methods. After Institutional Review Board approval, 120 unpremedicated children with a mean age of 26.5 ±21.4 months (M) and 28.1±19.9 months (P) were randomly assigned to receive a hypnotic induction dose of either M or P. Supplemental bolus injections of M or P were administered to maintain adequate sedation. The following parameters were measured: heart rate, oxygen saturation by pulse oximetry (SpO2), respiratory rate, end-tidal CO2 (PetCO2), side effects, and recovery and discharge times. Results. Spontaneous respiration was maintained in all patients, and ventilatory support was only necessary for 2 min in 1 M patient immediately after the induction dose. The mean loading and total doses for M were 2.3±0.7 and 6.1±3.3 mg/kg respectively, and for P 2.3±0.9 and 5.8±2.7 mg/kg. Following induction SpO2 <90% occurred in 0.49% with M and in 0.64% with P (n.s.). Apnoe >20 s was observed in 2 children each after M and P (n.s.). The frequency of hypoventilation (PetCO2>48 mmHg) was 0.36% in the M group and 0.71% in the P group (n.s.). MRI sequences had to be repeated in 5% of the children in each group because of spontaneous movements. The heart rate fell significantly during MRI in both groups, while P children had lower frequencies than M children (P<0.01). Recovery and discharge times were significantly shorter in the P group, at 0.8 min (0.08–4.8) and 2.2 min (0.2–15.0), compared to 1.5 min (0.3–28.5) and 3.5 min (0.6–40.0) in patients receiving P (P<0.01). No patient required admission to the postanaesthesia care unit and all were free from nausea and vomiting. Discussion. Intravenous sedation with M or P using the reported technique is a safe regimen for children undergoing elective MRI. The fast recovery and discharge times seem to offer advantages over general anaesthesia with endotracheal intubation. The faster recovery and discharge of only a few minutes after P compared with M is without clinical relevance.

Der i-STAT Analyzer

ZusammenfassungZielsetzung und Methoden: In der chirurgischen Operationseinheit und Intensivstation der Universitätsklinik wurden bei 49 Patienten arterielle Blutproben entnommen und simultan mit dem i-STAT Analyzer (Kartusche EG7+) und einem Referenzgerät ausgewertet. Die Kartusche EG7+ ermittelt die Parameter ionisiertes Kalzium, Kalium, Natrium, pH, pCO2, pO2 und Hämatokrit. HCO3, BE, SO2 und Hb werden aus diesen Daten errechnet. Der Hkt bzw. das Hb kann mit der speziellen Anpassung (HLM) für erniedrigtes Serumprotein z.B. während kardiopulmonalem Bypass unter Herz-Lungenmaschine (HLM) korrigiert werden. Ergebnisse: Mit dem Referenzgerät ABL 615 und EML 100 wurden die Korrelationen (r) für ionisiertes Kalzium (r=0,85), Kalium (r=1,0), Natrium (r=0,86), pH (r=0,99), pCO2 (r=0,98), pO2 (r=0,99), HCO3 (r=0,93), BE (r=0,93), Hb (r=0,46), Hb/HLM (r=0,95), Hkt (r=0,81) und Hkt/HLM (r=0,98) ermittelt. Die 95% Binominalverteilung der Differenzen lagen beim Kalium, Natrium, pCO2, pO2 und Hkt/HLM innerhalb der Vorgaben zur Qualitätssicherung der Bundesärztekammer. Die Meßwerte für ionisiertes Kalzium, pH und Hb/HLM lagen zwar außerhalb der empfohlenen Toleranzen der BÄK, sind aber für den klinischen Gebrauch akzeptabel. Im anästhesiologischen Bereich sollte zur Hkt- oder Hb Bestimmung immer die „HLM” Anpassung für erniedrigtes Serumprotein programmiert werden. Zusammenfassung: Der einfache Gebrauch, die Transportierbarkeit und eine Analysezeit der Blutproben von ca. 2,5 min sowie die Wirtschaftlichkeit bei geringstem Wartungsaufwand prädestinieren dieses Gerät auch für innerklinische Notfälle, z.B. im Schockraum oder auf Normalstation.AbstractExact and quick measurements of basic laboratory parameters are important in selected patients in the perioperative period. Depending on the capabilities of a hospital’s central laboratory, the anaesthesiologist may only obtain such laboratory tests after unacceptable delays. This problem may be overcome by a new bedside measurement device that has become available from i-STAT Corporation, Princeton, USA. The hand-held, battery-driven analyser accepts blood specimens that are injected into a disposable cartridge (EG7+) and measures acidity, blood gas tensions, haematocrit, and electrolytes. The aim of this study was to determine the accuracy of such measurements by comparing them with measurements obtained by conventional laboratory test methods. Methods: Heparinised arterial blood specimens were collected in duplicate from 49 surgical patients. Measurements of ionised calcium (Ca), sodium (Na), potassium (K), pH, pCO2, pO2, base excess (BE), haematocrit (Hct), and haemoglobin (Hb) obtained by the i-STAT analyser were compared with measurements from the calibrated analysers ABL 615 and EML 100 (Radiometer, Copenhagen). Because the i-STAT analyser calculates the Hb concentration from a conductometrically measured Hct, 19 blood specimens were centrifuged in order to compare test results with conventionally obtained Hct and Hb values. As the Hct test sensitivity with the i-STAT changes with diluted blood due to its low albumin concentration, Hct and Hb measurements during cardio-pulmonary bypass (CPB) must be corrected by activating an analyser-implemented correction algorithm (Hct/CPB and Hb/CPB). Correlation analysis was performed between conventional measurements and i-STAT values (Ca, Na, K, Hct, pCO2, pO2), between values that the i-STAT analyser derives (Hb, HCO3, BE) and conventionally obtained results, and between normal and CPB-corrected Hct and Hb values. Accuracy was judged according to the national quality standard, whic h requires test results to lie within the 95% confidence interval of conventional tests. Results: Each blood specimen was analysed: erroneous results or technical failures did not occur. Measurement of one set of i-STAT values required 2.5 min. Correlation coefficients (r) between conventional and i-STAT results were: 0.85 for CA, 1.0 for K; 0.86 for Na; 0.99 for pH; 0.98 for pCO2; 0.99 for pO2; 0.93 for HCO3; 0.93 for BE; 0.46 for Hb values not corrected for CPB and 0.95 for CPB-corrected Hb; and 0.74 for Hct values not corrected for CPB and 0.98 for CPB-corrected Hct. The correlation coefficient for Hct between centrifuged and CPB-uncorrected i-STAT values was 0.81 and that for CPB-corrected values was 0.98. National accuracy requirements were not met for tests of: Ca (by 0.02 mmol/l); pH (by 0.01); pO2 including hyperoxic values (by 26.7 mmHg, but were met for pO2 values <200 mmHg); Hb (by 1.6 g/dl); Hb/CPB (by 0.8 g/dl); and Hct (by 6.5%, but were met for Hct/CPB values). All other tests fulfilled the required standards. Conclusion: This analyser is easy to use, reliable, and portable, and therefore suitable for the operating room, for analyses during emergencies, on peripheral wards, for preclinical screening, or at times when availability of lab tests is time-consuming or limited. The test accuracy for electrolytes, blood gases, and Hb is high enough to justify routine use of the i-STAT analyser in clinical practice. That the nationally required quality standards for Ca, pH, and Hb were not met is not of importance because the measured deviation was too small to have clinical relevance. When analysing diluted blood with a low Hct and low oncotic pressure, it is important to activate the analyser’s correction algorithm „CPB”, because the obtained results will then comply with the required accuracy.

Zusatz von Fentanyl zur Bupivacain : Periduralanalgesie bei Sectio Caesarea

Zusammenfassung43 Patientinnen zur Sectio caesarea erhielten peridural, randomisiert und doppelblind entweder Bupivacain 0,5%+0,1 mg Fentanyl (B+F, n=22) oder Bupivacain 0,5%+2 ml NaCl 0,9% (Bup, n=21) präoperativ. Die intraoperative Schmerzintensität wurde anhand der visuellen Analogskala (VAS) ermittelt. Analgesiedauer, Apgarscores, umbilikale Blutgaswerte und Häufigkeit von Nebenwirkungen wurden verglichen. Mütterliche und umbilikale Fentanylplasmaspiegel wurden im Verlauf bestimmt. Der Anteil schmerzfreier Patientinnen (VAS= 0) während der Uteruseventration und beim Wundverschluß war mit 82% in der B+F-Gruppe um rund 40% höher als bei Patientinnen ohne Fentanyl; (p<0,05). Fentanylzusatz verursachte häufiger Übelkeit und Juckreiz. Die mittleren venösen Fentanylkonzentrationen betrugen vor bzw. 20 und 40 min nach periduraler Injektion je 0,25 ng/ml (range 0,02–0,32); 0,55 ng/ml (0,12–1,14) und 0,52 ng/ml (0,26–1,04). Bei Abnabelung betrug die Konzentration im mütterlich-venösen Blut 0,58 ng/ml (0,14–1,18), während umbilikalarteriell und -venös 0,51 ng/ml (0,04–1,8) bzw. 0,41 ng/ml (0,18–1,2) gemessen wurde. Eine klinische Atemdepression wurde nie beobachtet. Die 5 min Apgarscores aller Neugeborenen betrugen >8, umbilikale Blut pH-Werte <7,20 wurden nicht gemessen. Der peridurale Fentanylzusatz bewirkt eine signifikant bessere intraoperative Analgesie während der Schnittentbindung. Es fanden sich keine Hinweise für eine Gefährdung der mütterlichen oder fötalen Sicherheit.AbstractEpidural anaesthesia for elective caesarean section can have advantages over general anaesthesia. The anaesthesiologist can avoid endotracheal intubation as well as fetal depression following placental transfer of systemic anaesthetics. However, despite reaching an effective blockade preoperatively, intraoperative discomfort and pain may occur during epidural anaesthesia with local anaesthetics alone, necessitating supplemental systemic analgesics or even conversion to general anaesthesia [21]. Addition of epidural fentanyl has been shown to improve onset and quality of perioperative analgesia without evident side effects for mother or newborn [24]. Nevertheless, administration of epidural opioids before cord clamping is still hotly debated, some fearing maternal and or neonatal depression [6, 26]. The aim of the present study was to investigate the quality of analgesia, associated side effects and the resulting maternal and neonatal plasma opiate concentrations after a single preoperative addition of 0.1 mg fentanyl to epidural bupivacaine analgesia in comparison to epidural bupivacaine analgesia alone. Methods. Following governmental and ethics committee approval, 43 elective consenting patients for caesarean section were randomized to receive double-blind injections of either 8 ml 0.5% bupivacaine+0.1 mg fentanyl (B+F group, n=22) or 8 ml 0.5% bupivacaine +2 ml saline (Bup group, n=21) into an epidural catheter. In both groups additional injections of bupivacaine were given to achieve sensory blockade up to T4. Systolic blood pressure, heart and respiratory rates were measured regularly. Quality of intraoperative pain relief was assessed at delivery, uterine eventration, and during uterine and abdominal closure using a visual analogue scale (VAS). The duration of postoperative analgesia was compared between groups, as well as the incidence of nausea, itching or sedation. Similarly, Apgar scores and umbilical arterial and venous blood gas analyses were compared. Fentanyl concentrations were determined in maternal venous blood sampled before and 20 and 40 min after epidural injection and at birth, and in umbilical venous and arterial blood sampled after delivery. Radioimmunoassay analysis was performed from plasma specimens centrifuged and frozen at −20° C [19]. The statistical level of significance was defined as P<0.05. Results. Groups were comparable regarding age, weight and time of gestation. Total bupivacaine doses and injection to delivery times were similar in both groups. Figure 1 shows that there were 40% more pain-free (VAS=0) patients in the B+F group during uterine eventration and wound closure (P<0.05). Mean postoperative duration of analgesia was significantly longer in the B+F group (382 vs 236 min). The rate of nausea and mild itching was significantly higher in the B+F group. Respiratory depression was never detected in patients or newborns. Small group differences in blood pressure or respiratory rate were inconstant and clinically irrelevant, as were differences in umbilical venous pCO2. One hundred and twenty-five blood samples were analysed for fentanyl concentrations. The mean fentanyl concentration before epidural injection was not zero, but 0.25 ng/mg (range 0.02–0.32). Maternal concentrations at 20 and 40 min after injection were 0.55 ng/ml (0.12–1.14) and 0.52 ng/ml (0.26–1.04) (Fig. 3). At delivery, mean maternal fentanyl concentration was 0.58 ng/ml (0.14–1.18); mean umbilical arterial and venous concentrations were 0.51 ng/ml (0.04–1.8) and 0.41 ng/ml (0.18–1.2), respectively. Rare results of fentanyl concentrations >1.0 ng/ml correlated neither with sedation, maternal respiratory rate and side effects, nor with Apgar scores and umbilical blood gas values. No Apgar score at 5 min was below 9, and no umbilical pH was below 7.20. Conclusion. We conclude that preoperative epidural addition of 0.1 mg fentanyl to 0.5% bupivacaine significantly improves intraoperative pain relief during elective caesarean section and prolongs postoperative analgesia. This important advantage of fentanyl is associated with an increased incidence of nausea and mild itching. No clinically significant fentanyl-associated depression of vigilance could be detected in the mother or newborn. The resulting plasma fentanyl concentrations are within safe limits. When administered epidurally and preoperatively for caesarean section, maternal plasma levels of fentanyl do not decrease significantly until birth. In the radioimmunoassay an unknown substance cross-reacts like fentanyl.

Midazolam does not antagonize fentanyl-mediated analgesia in surgical patients

STUDY OBJECTIVE To determine whether midazolam possesses a clinically significant antianalgesic action in surgical patients. DESIGN Randomized, controlled study. SETTING Inpatient anesthesia at a university department of neurosurgery. PATIENTS 2 groups of 10 patients each who were scheduled for supratentorial brain surgery, did not have elevated intracranial pressure, and were free from systemic disease. INTERVENTIONS Patients underwent anesthesia induction with hexobarbital, succinylcholine, and pancuronium; anesthesia was maintained with injections of droperidol-fentanyl (Group 1) or with midazolam-fentanyl (Group 2) following a predetermined repetitive dosing schedule, such that fentanyl 0.1 mg was injected upon predominant increases in heart rate, whereas droperidol 2.5 mg or midazolam 2.5 mg was injected upon increases in blood pressure. MEASUREMENTS AND MAIN RESULTS Duration of anesthesia and invasiveness of surgery were similar in both groups. The amount of fentanyl required was 0.55 +/- 0.18 mg/hr (mean +/- SD) in Group 1 and 0.53 +/- 0.17 mg/hr in Group 2. Injections of droperidol 7.5 +/- 3.4 mg/hr (Group 1) and midazolam 5.9 +/- 2.3 mg/hr (Group 2) were administered intraoperatively. This redosing regimen was associated with uninterrupted hemodynamic stability, indicating comparable and adequate anesthetic depth. Plasma concentrations of metabolites and hormones indicative of humoral stress activation did not differ between groups. CONCLUSION Under these clinical conditions, the administration of midazolam, when compared with droperidol, was not associated with signs of any antagonistic or antianalgesic action toward fentanyl-mediated analgesia.