Georges Rolly

Comparative study of limited intentional normovolaemic haemodilution in patients with left main coronary artery stenosis

Intentional normovolaemic haemodilution is a blood saving technique which can be performed when major blood loss is expected. Severe coronary artery disease and particularly left main stenosis are considered a contraindication for intentional normovolaemic haemodilution. The effects and complications of limited intentional normovolaemic haemodilution in patients with left main coronary artery stenosis scheduled for coronary artery bypass grafting were evaluated. Patients were randomly allocated to two groups: group A (n = 15) underwent limited intentional normovolaemic haemodilution to a haematocrit of 34%; group B(n = 15), no intentional normovolaemic haemodilution was performed. In both groups succinyl‐linked gelatin was used to maintain normovolaemia. Haemodynamic parameters were kept as constant as possible. In group A, a mean (SD) volume of 785 (250) ml of blood was withdrawn [range 500–1200 ml]. ST segment changes occurred on the ECG in three patients in each group. There were no statistically significant differences for frequency, maximum deflection and duration of ST‐segment changes. Limited intentional normovolaemic haemodilution can be performed safely in patients with left main coronary artery stenosis. In this study it was not associated with increased frequency, severity or duration of ST‐segment changes, or with arrhythmias or haemodynamic instability.

EEG and SEMG monitoring during induction and maintenance of anesthesia with propofol

SummaryPropofol has been used as IV induction (2 mg/kg) and maintenance agent (150 µg/kg/min and 100 µg/kg/min after 30 min), combined with N2O/O2 in 16 premedicated (atropine 0.5 mg, Thalamonal 2 ml IM) and mechanically ventilated patients, having ear surgery or arthroscopy.Cranial biopotentials were analysed by 2 different techniques:1.The Anesthesia and Brain Activity Monitor (ABM Datex) providing the zero crossing frequency (ZXF) as a value for the mean frequency of the EEG signal during a considered time interval, the mean integrated voltage (MIV) as a mean value of the amplitude of the same EEG signal and the spontaneous electromyography of the frontal muscle (SEMG).2.The EEG trend monitor (rough signal, spectral analysis (S.A.), procentual display).n The EEG changes, recorded during propofol anesthesia, are comparable with both techniques. Induction is characterised by a decrease in ZXF, caused by a procentual increase in the low frequency bands (the delta band represents more than 80% of the total power). During the perfusion period an increase in the power of the alpha band (10% to 40%) and a decrease in the delta band is noticed. The ZXF regains its original value. At the end of the procedure the ZXF increases (beta band to more than 30%).A correlation was looked for between the EEG changes and the propofol blood concentrations. The higher the propofol blood concentrations, the more pronounced the low frequency bands. The appearance of beta waves or a ZXF greater than 10 Hz indicates pending arrousal.

The mechanisms of carbon monoxide production by inhalational agents.

Carbon monoxide can be formed when volatile anaesthetic agents such as desflurane and sevoflurane are used with anaesthetic breathing systems containing carbon dioxide absorbents. This review describes the possible chemical processes involved and summarises the experimental and clinical evidence for the generation of carbon monoxide. We emphasise the different conditions that were used in the experimental work, and explain some of the features of the clinical reports. Finally, we provide guidelines for the prevention and detection of this complication.

Only Carbon Dioxide Absorbents Free of Both NaOH and KOH Do Not Generate Compound A during In Vitro Closed-system Sevoflurane Evaluation of Five Absorbents

BackgroundInsufficient data exist on the production of compound A during closed-system sevoflurane administration with newer carbon dioxide absorbents. MethodsA modified PhysioFlex apparatus (Dräger, Lübeck, Germany) was connected to an artificial test lung (inflow at the top of the bellow ≅ 160 ml/min CO2; outflow at the Y piece of the lung model ≅ 200 ml/min, simulating oxygen consumption). Ventilation was set to obtain an end-tidal carbon dioxide partial pressure of approximately 40 mmHg. Various fresh carbon dioxide absorbents were used: Sodasorb (n = 6), Sofnolime (n = 6), and potassium hydroxide (KOH)–free Sodasorb (n = 7), Amsorb (n = 7), and lithium hydroxide (n = 7). After baseline analysis, liquid sevoflurane was injected into the circuit by syringe pump to obtain 2.1% end-tidal concentration for 240 min. At baseline and at regular intervals thereafter, end-tidal carbon dioxide partial pressure, end-tidal sevoflurane concentration, and canister inflow (T°in) and canister outflow (T°out) temperatures were measured. To measure compound Ainsp concentration in the inspired gas of the breathing circuit, 2-ml gas samples were taken and analyzed by capillary gas chromatography plus mass spectrometry. ResultsThe median (minimum–maximum) highest compound Ainsp concentrations over the entire period were, in decreasing order: 38.3 (28.4–44.2)* (Sofnolime), 30.1 (23.9–43.7) (KOH-free Sodasorb), 23.3 (20.0–29.2) (Sodasorb), 1.6 (1.3–2.1)* (lithium hydroxide), and 1.3 (1.1–1.8)* (Amsorb) parts per million (*P < 0.01 vs. Sodasorb). After reaching their peak concentration, a decrease for Sofnolime, KOH-free Sodasorb, and Sodasorb until 240 min was found. The median (minimum–maximum) highest values for T°out were 39 (38–40), 40 (39–42), 41 (40–42), 46 (44–48)*, and 39 (38–41) °C (*P < 0.01 vs. Sodasorb), respectively. ConclusionsWith KOH-free (but sodium hydroxide [NaOH]–containing) soda limes even higher compound A concentrations are recorded than with standard Sodasorb. Only by eliminating KOH as well as NaOH from the absorbent (Amsorb and lithium hydroxide) is no compound A produced.

Production of compound A and carbon monoxide in circle systems: an in vitro comparison of two carbon dioxide absorbents*

Two new generation carbon dioxide absorbents, DrägerSorb® Free and Amsorb® Plus, were studied in vitro for formation of compound A or carbon monoxide, during minimal gas flow (500u2003ml.min−1) with sevoflurane or desflurane. Compound A was assessed by gas chromatography/mass spectrometry and carbon monoxide with continuous infrared spectrometry. Fresh and dehydrated absorbents were studied. Mean (SD) time till exhaustion (inspiratory carbon dioxide concentration ≥u200a1u2003kPa) with fresh absorbents was longer with DrägerSorb® Free (1233 (55) min) than with Amsorb® Plus (1025 (55) min; pu2003<u20030.01). For both absorbents, values of compound A were <u200a1u2003ppm and therefore below clinically significant levels, but were up to 0.25u2003ppm higher with DrägerSorb® Free than with Amsorb® Plus. Using dehydrated absorbents, values of compound A were about 50% lower than with fresh absorbents and were identical for DrägerSorb® Free and Amsorb® Plus. With dehydrated absorbents, no detectable carbon monoxide was found with desflurane.

Theatre monitor alarm settings: a pilot survey in Scotland and Belgium

The use of alarms on operating theatre equipment was explored in a questionnaire to anaesthetists in Belgium and Scotland. They were presented with a scenario of a fit male having an anaesthetic for an abdominal operation. The overall response rate was 72%, giving 100 records for analysis. The responses from Scottish and Belgian anaesthetists were similar except for views on setting an upper limit for systolic arterial pressure; Scottish anaesthetists seemed relatively unwilling to set an upper systolic arterial pressure limit. Beyond this, the respondents considered alarms to be a method of detecting problems before they occur and they readjust alarms for each patient. They would set systolic arterial pressure alarms 30u2003mmHg above and below the patients normal pressure, the heart rate alarms 30u2003bpm above and 20u2003bpm below the actual rate, and the peripheral oxygen saturation lower alarm limit to 90%.