F. Fleischer

Pulse contour analysis versus thermodilution in cardiac surgery patients

Background:  Previous studies have demonstrated that there is a lack of agreement between intermittent cold bolus thermodilution (ICO) and a semicontinuous method with dilution of heat (CCO) in cardiac surgical patients following hypothermic extracorporeal circulation (HCPB). Therefore, the aim of the present study was to compare both ICO and CCO with continuous pulse contour analysis (PCCO): a method based on a fundamentally different principle of determining cardiac output (CO).

Tussive effect of a fentanyl bolus administered through a central venous catheter

One hundred and ten male patients scheduled for coronary artery bypass grafting were allocated randomly into one of three groups. Patients in group A received fentanyl 7 μg/kg via a central venous catheter, those in group B were given fentanyl 7 μg/kg through a peripheral venous cannula, and patients in group C received sterile water via a central venous catheter. In group A, 45.9% of patients coughed after injection of fentanyl; the mean onset time from the end of fentanyl administration to the beginning of coughing was 10.6 seconds. Only one patient in group B and no patient in the control group exhibited a cough response (p < 0.0001). We hypothesise that fentanyl can evoke the pulmonary chemoreflex.

Continuous versus intermittent cardiac output measurement in cardiac surgical patients undergoing hypothermic cardiopulmonary bypass

OBJECTIVE Continuous thermodilution cardiac output (CCO) measurement was clinically evaluated in patients who underwent coronary revascularization using hypothermic low-flow, low-pressure cardiopulmonary bypass (CPB). DESIGN Prospective study. SETTING University hospital setting. PARTICIPANTS 30 cardiac surgical patients. INTERVENTIONS CCO was correlated to standard bolus thermodilution cardiac output (ICO) obtained at end-expiration. MEASUREMENTS AND MAIN RESULTS Measurements were taken at selected time points (n = 18) before anesthesia induction, before CPB, and 5 minutes to 12 hours after CPB. A total of 540 data pairs were thus obtained. ICO ranged from 1.9 to 9.9 L/min, CCO from 1.5 to 9.9 L/min. Correlation between ICO and CCO was highly significant (r = 0.872; p < 0.01), accompanied by an excellent accuracy (bias -0.0213 L) and precision (0.59 L) before CPB and more than 45 minutes after CPB. However, during the first 45 minutes after CPB, there was no correlation (r = 0.273) between ICO and CCO, and ICO tended to be relatively high, whereas CCO measurements showed relatively low values. During the first 45 minutes after hypothermic CPB, but not during the ensuing time period, central blood temperature decreased, which may be interpreted as a lack of thermal equilibration between central and peripheral compartments. It is hypothesized that thermal instability in combination with increased respiratory variations in pulmonary artery blood temperature caused inhomogenous rewarming of different body sites and might be the main reason for the lack of correlation between ICO and CCO. CONCLUSIONS Despite an excellent correlation, accuracy, and precision between CCO and ICO before CPB and more than 45 minutes after hypothermic CPB, a lack of correlation in the early phase after CPB has been found. Further investigation is needed to elucidate the underlying cause of these findings and to clarify whether ICO or CCO or both fail to represent the real cardiac output up to 45 minutes after weaning from hypothermic CPB.

Adverse haemodynamic effects of high-dose aprotinin in a paediatric cardiac surgical patient

High‐dose aprotinin for reduction of intra‐ and postoperative blood loss was associated with profound hypotension and flushing in a 3.5‐year‐old child who underwent cardiac surgery. Treatment with noradrenaline and intravenous fluid was required. Cardiovascular stability was restored after 10 minutes.

Effects of thiopentone/suxamethonium on intraocular pressure after pretreatment with alfentanil

SummaryThe effects of pretreatment with alfentanil on intraocular pressure (IOP) were investigated in 40 patients undergoing ophthalmic surgery. Patients were randomly allocated to two study groups. Group 1 patients (n=20) received alfentanil 15 μg · kg−1, vecuronium 0.01 mg · kg−1, thiopentone 3-4 mg · kg−1, and suxamethonium 1 mg · kg−1 for anaesthetic induction, whereas patients in group 2 (n = 20) received vecuronium 0.01 mg · kg−1, thiopentone 3–4 mg · kg−1, and suxamethonium 1 mg · kg−1. A total of seven measurements of intraocular pressure were taken in each patient, starting before premedication and ending after extubation of the trachea. In group 2 patients, there was an increase in IOP after endotracheal incubation. In group 1 patients, a decrease in IOP occurred which was related to the decrease in arterial blood pressure. We conclude that alfentanil pretreatment can prevent the increase in IOP following suxamethonium administration.

Serum aluminium levels of intensive care patients treated with two different antacids for prevention of stress ulceration

We studied the serum aluminium levels of 30 intensive care patients receiving six daily doses of magaldrate (Riopan®) or aluminium hydroxide (Trigastril®). In both groups we found a significant rise of the serum aluminium concentration (p<0.01) following administration of the antacid solutions. Examination on day 9 and 15 the magaldrate group showed significantly (p<0.05) lower aluminium levels than the aluminium hydroxide group. An increase up to the critical serum aluminium level of 100 ng/ml occurred in none of the patients that all had normal or slightly impaired renal function. Therefore routine measurements of serum aluminium levels in patients without renal impairment are not considered necessary following antacid therapy. However, we recommend the use of antacids with an aluminium absorption rate as low as possible.

Evoked potential monitoring during repeatedly induced ventricular fibrillation for internal defibrillator implantation.

Repeated induction of ventricular fibrillation (VF) with circulatory compromise during implantable cardioverter defibrillator (ICD) testing may cause cerebral injury. To test this hypothesis, somatosensory evoked potentials (SEP), a more sensitive marker of injury, were recorded in patients (N = 10) undergoing ICD implantation. SEP were recorded before induction of anesthesia, after induction of anesthesia, before and at several times following induction of VF. Possible modifying factors of the SEP measurements such as anesthetic application, blood pressure, body temperature, and hematocrit remained constant throughout the operations. Central conduction time was unaffected by ICD defibrillation testing. Amplitude of SEP primary complexes was transiently reduced at 34.9% (P < 0.01) by defibrillation testing, but returned to control within 10 minutes after testing. It is concluded that while ICD defibrillation testing may produce transient changes in SEP, there is no evidence of residual cerebral injury.

Changes in oxygen saturation following low-dose intramuscular ketamine in paediatric cardiac surgical patients

Forty‐seven children with congenital heart disease received ketamine 3 mg kg−1 intramuscularly as a pre‐induction agent. During the 10 min observation period following ketamine administration no adverse cardiovascular or respiratory side‐effects were seen. Arterial oxygen saturation as measured by pulse oximetry remained constant in all patients. In the group of children with cyanotic heart disease, there was a trend towards improvement of oxygen saturation which became significant 10 min after ketamine administration. We conclude that ketamine is a useful pre‐induction agent when used in the appropriate dose range.

Cisatracurium bei Koronarbypassoperationen : ein Vergleich mit Pancuronium : Hämodynamische und neuromuskuläre Effekte bei Patienten unter chronischer β-Blockertherapie

ZusammenfassungZiel dieser Untersuchung war ein Vergleich von Cisatracurium und Pancuronium hinsichtlich Hämodynamik und neuromuskulärer Wirkungen bei der Narkoseeinleitung β-blockierter Koronarbypasspatienten (ASA III, gute bis mäßig eingeschränkte LV-Funktion).Doppelblind prospektive Untersuchung an 60 Patienten: Jeweils 20 Patienten erhielten bei Einleitung einer Sufentanil/Midazolam/Etomidatanästhesie zur Muskelrelaxation Pancuronium 0,1 mg/kg (Gruppe P) oder Cisatracurium (0,1 mg/kg: Gruppe C2; 0,2 mg/kg: Gruppe C4). Die Hämodynamik wurde mittels EKG, invasiver arterieller Druckmessung und pulmonalarteriellem Katheter, die neuromuskuläre Übertragung mittels Elektromyographie gemessen. Die Herzfrequenz fiel signifikant ab in Gruppe C2 von 62,7±9,3 min−1 vor Einleitung auf 50,2±6,8 min−1 3 min nach Einleitung, in Gruppe C4 von 63,8±9,3 auf 54,3±11 min−1, blieb dagegen in Gruppe P (63±19 und 62,4±13,2 min−1) unverändert. Dieser Unterschied blieb signifikant bis 60 min nach Einleitung. Die Anschlagszeit betrug 5,2±3,4 min in Gruppe P, 6,4±2,1 min in Gruppe C2 und 2,9±1,2 min in Gruppe C4.Schlussfolgerung. Bei Narkoseeinleitung koronarchirurgischer Patienten mit hochdosierten Opioiden muss bei Anwendung von Cisatracurium im Gegensatz zu Pancuronium mit dem Auftreten einer interventionsbedürftigen Bradykardie gerechnet werden.AbstractObjective. The aim of the study was to compare haemodynamic and neuromuscular effects of cisatracurium and pancuronium in patients undergoing coronary artery bypass grafting (ASA III, good or moderately impaired LV function) who were chronically medicated with β-adrenergic blocking agents.Methods. 60 Patients were randomly assigned in a double-blind fashion to receive sufentanil/midazolam/etomidate and either pancuronium (2xED95, group P) or cisatracurium (2xED95, group C2 and 4xED95, group C4). Haemodynamic variables were measured using arterial and pulmonary arterial catheters, neuromuscular transmission was measured using electromyography.Results. The heart rate was significantly lower in group C2 (50,2±6,8 bpm) and in group C4 (54,3±11 bpm) than in the pancuronium group (62,4±13,2 bpm) 3 min after induction of anaesthesia and until 60 min after induction. None of the other haemodynamic parameters showed any difference between groups. Onset time was 5.22±3.43 min in group P, 6.42±2.1 min in group C2 and 2.92±1.2 min in group C4.Conclusion. Under high-dose opioid induction, bradycardia must be considered if cisatracurium is administered to cardiac surgery patients.

Drug therapy in coronary heart disease – perioperative implications

Zusammenfassung. Jede 8. Anästhesie wird bei einem Patienten mit koronarer Herzerkrankung (KHK) bzw. bei Risikogruppen durchgeführt. Perioperativ finden sich bei diesen Patienten in 20 – 40% überwiegend klinisch stumme Myokardischämien. Diese korrelieren eindeutig mit der Rate postoperativer kardialer Komplikationen. Die Reduktion perioperativer kardialer Komplikationen ist eine wichtige Aufgabe des Anästhesisten. Neben einer hämodynamisch stabilen Führung kann dies durch den gezielten Einsatz antiischämischer Medikamente erreicht werden. NO-Donatoren (Nitrate, Molsidomin) bewirken eine koronare und systematische Gefäßdilatation mit konsekutiver akuter Verminderung der Füllungsdrucke. Bei intraoperativer Myokardischämie können Nitrate das Mittel der ersten Wahl darstellen. β-Blocker reduzieren die Ischämierate stärker als Nitrate. Sie wirken auch bei Ischämien, die nicht mit einem Anstieg der Herzfrequenz einhergehen und zeigen selbst bei einmaliger präoperativer Gabe günstige Effekte auf die perioperative Inzidenz von Hypertension, Tachykardien und Myokardischämien. Die Weiterführung einer chronischen oralen Therapie mit Kalziumantagonisten bis zum Morgen der Operation reduziert bei koronar-chirurgischen Patienten die Rate perioperativer Ischämien und Myokardinfarkte. β-Blocker verstärken diesen Effekt. Thrombozytenaggregationshemmer haben eine hohe prognostische Relevanz bei koronarkranken Patienten. Sie verursachen jedoch perioperativ eine signifikante Erhöhung der Blutungsrate. Von Hochrisikopatienten abgesehen wird daher das Absetzen dieser Substanzen 5 – 10 Tage vor einer größeren Operation empfohlen. Pilotstudien zeigen auch für α2-Agonisten eine Reduktion der Rate perioperativer Myokardischämien. Schlußfolgerung:β-Blocker, Kalziumantagonisten, NO-Donatoren und wahrscheinlich auch α2-Antagonisten können bei Risikogruppen die Rate perioperativer Myokardischämien und folgender kardialer Komplikationen reduzieren. Eine chronische, antianginöse Medikation sollte daher mit Ausnahme der Thrombozytenaggregationshemmer bis zum Tag der Operation und postoperativ so früh als möglich weitergeführt werden. Bei einem intraoperativen Einsatz sind Interaktionen mit Anästhetika zu beachten.Abstract.Objective. The aim of our review is to summarize relevant data on the perioperative use of anti-ischaemic drugs in patients at risk for or with proven coronary heart disease. Data sources. The accessible medical literature according to current electronic information sources was explored. Results. One in every eight general anaesthetics is administered to a patient at risk for or with proven coronary heart disease. Of these patients, it is estimated that 20% – 40% have perioperative myocardial ischaemia (PMI), the majority being nonsymptomatic. This figure correlates with the occurrence of postoperative cardiac complications and myocardial infarction. The anaesthetist therefore has an important role to play in reducing the rate of perioperative cardiac sequelae. This can be achieved with good control of haemodynamic stability and the timely and appropriate use of antiischaemic drugs. Nitrocompounds (nitrates, molsidomine) serve as the gold standard in current angina pectoris treatment. Acting as coronary and systemic vasodilators, they effect an immediate reduction in preload and have been shown to be the drugs of first choice for intraoperative myocardial ischaemia. Beta-blockers reduce the rate of PMI to a greater extent than nitrates. They are also effective in myocardial ischaemia not accompanied by an increased heart rate. Single pre-operative administration of beta-blockers has also been shown to be beneficial in reducing theincidence of perioperative tachycardia, hypertension, and PMI. Consequently, such one-time medication can be considered for previously untreated high-risk patients presenting for surgery. The continuation of oral calcium channel blockers to the morning of surgery also reduces the rate of PMI and myocardial infarction in coronary-bypass patients, and combination with beta-blockers enhances this effect. Intra-operative diltiazem infusions are similarly advantageous in this patient group. In addition to nitrates, calcium antagonists are the drug of choice for coronary vasospasm. Drugs inhibiting platelet aggregation have a particular role in patients with coronary heart disease, however, they also cause increased perioperative bleeding. Consequently, it is recommended that these medications be discontinued 5 – 10 days prior to major surgery, with the exception of high-risk patients. Pilot studies using alpha2-agonists have shown reduced anaesthetic requirements and a reduction in PMI. The perioperative relevance of these drugs is currently being investigated. Conclusions. Beta-blockers, calcium channel blockers, nitrates, and possibly alpha2-agonists lead to reduced rates of PMI and other cardiac complications in risk patients. Current anti-anginal medications, with the exception of anti-platelet agents, should be maintained to the day of surgery and continued as soon as possible thereafter. All of these drugs except anti-platelet agents may also be used intra-operatively, however, possible interactions with anaesthetic agents should be carefully considered.