Summary

Background and objective: For the treatment of patients with adult respiratory distress syndrome and acute lung injury bedside measurements of regional lung ventilation should be considered for optimizing ventilatory settings. The aim was to investigate the effect of positive end-expiratory pressure (PEEP) on regional ventilation in mechanically ventilated patients at the bedside by electrical impedance tomography. Methods: Eight mechanically ventilated patients were included in the study. PEEP levels were increased from 0 to 5, 10, 15 mbar and back to 0 mbar. Regional ventilation in 912 regions of the thorax was investigated at each PEEP by electrical impedance tomography. The obtained regions were divided in four groups: none (none and poorly ventilated regions including chest wall and mediastinum), bad, moderate and well-ventilated regions. Results: Increasing the PEEP stepwise from 0 to 15 mbar decreased the non-ventilated regions (none: 540 regions at PEEP 0 and 406 regions at PEEP 15). In contrast, the other regions increased (bad: 316 regions at PEEP 0 and 380 regions at PEEP 15; moderate: 40 regions at PEEP 0 and 100 regions at PEEP 15; well: 0 region at PEEP 0 and 34 regions at PEEP 15 (median values)) indicating an improvement of regional ventilation. Conclusions: Increasing PEEP in mechanically ventilated patients reduces none ventilated regions (atelectasis). Furthermore, it leads to a shift from none and bad ventilated regions to moderately and well-ventilated regions. Electrical impedance tomography is a bedside technique and might be an alternative to computed tomography scan to assess aerated lung regions.

Summary

Background and objective: The purpose of this prospective randomized study was to assess the value of pressure support ventilation during inhalational induction with sevoflurane in adult patients. Methods: Thirty-five adult patients, ASA I–II and scheduled for ear nose throat surgery were studied. Vital capacity induction with 8% sevoflurane in 8 L min−1 oxygen was performed. Pressure support ventilation was used in Group 1 with pressure set at 15 cmH2O. In Group 2, patients breathed spontaneously. After 2 min, sevoflurane was set to 3% and remifentanil 1 μg kg−1 was injected over 2 min followed by an infusion of 0.1μg kg−1 min−1. Two minutes after the end of the bolus, intubation was performed. Bispectral index, oxygen saturation, respiratory rate, end-tidal carbon dioxide, expired tidal volume and expired sevoflurane concentration were recorded every minute. Results: Eighteen patients were included in Group 1 and 17 in Group 2. Saturation, respiratory rate and end-tidal carbon dioxide were similar in the two groups. Expired tidal volume was significantly higher and bispectral index values significantly lower in Group 1. Intubating conditions were better in Group 1. Conclusions: Pressure support ventilation provides both better ventilation and deeper level of anaesthesia during inhalation induction with sevoflurane.

Summary

Background and objective: Cardiopulmonary resuscitation should not be interrupted until the return of spontaneous circulation or the decision to withhold further treatment. There are no data on how consistent in-hospital cardiopulmonary resuscitation is performed. Accordingly, the aim of the present study was to identify length and type of unnecessary interruptions in simulated cardiac arrests. Methods: The study was carried out in a patient simulator. A scenario of cardiac arrest due to ventricular fibrillation was used. Resuscitation teams consisted of three nurses, a resident and a staff physician. Using videotapes recorded during simulations, the activities of the teams were coded in 5-s intervals. Unnecessary interruptions were defined as any interruptions in cardiac massage of 10 s or more that were not caused by defibrillation or endotracheal intubation. Results: Twelve teams were studied. The total time of possible cardiac massage was 414 ± 125 s. In each team at least one unnecessary interruption occurred (range 1–5). Interruptions mounted up to 65 ± 40 s (range 20–155) or 16 ± 10% (range 5–41) of the total time of possible cardiac massage. Failure to swiftly resume cardiac massage after an unsuccessful defibrillation accounted for 14 of 39 episodes and for 44 ± 40% of the time of unnecessary interruptions. The debriefings revealed that participants had generally not noticed the unnecessary interruptions during the simulation. Conclusions: The present study identified a significant amount of unnecessary interruptions in cardiac massage. These interruptions were not noticed by the health-care workers involved.

Summary

Background and objective: We studied the effect of different recumbent positions (supine, left and right lateral decubitus), on arterial oxygenation in 42 valvular heart disease patients planned for cardiac surgery. All patients had cardiomegaly (cardiothoracic ratio ≥0.5) in their chest X-rays. Their left ventricular end-diastolic diameter was also noted from the preoperative echocardiogram. Methods: Arterial blood gas analysis was performed in supine, left and right lateral positions after keeping the patient in a given position for 15 min. During this period all patients received 35% oxygen supplementation. Results: Arterial oxygen tension and haemoglobin saturation were significantly higher in the right lateral position (PaO2 = 120.6 ± 29.5 mmHg, SaO2 = 98.1 ± 1.4%) than in supine (PaO2 = 111.0 ± 30.6 mmHg, SaO2 = 97.6 ± 2.2%) and left lateral positions (PaO2 = 109.7 ± 32.0 mmHg, SaO2 = 97.6 ± 1.7%; mean ± SD; P < 0.01). There was no significant difference in arterial oxygenation between left lateral and supine positions (P > 0.05). The change in PaO2 and SaO2 with change of posture from left to right was significantly related to left ventricular end-diastolic diameter (r = 0.50 and r = 0.63, respectively; Pearson correlation). Repeated measures of analysis of variance with left ventricular end-diastolic diameter as a covariate showed a significant change in arterial PaO2 with posture (P = 0.011). Conclusion: Right lateral posture improves arterial oxygenation in the valvular heart disease patient with an enlarged left ventricle. In the preoperative period, these patients may benefit from a right lateral posture when lying in bed.

Summary

Background and objective: The purpose of this study was to compare the characteristics of epidural catheter insertion via the midline or the paramedian approach with regard to ease of catheter insertion, incidence of paraesthesias and efficacy of epidural block. In addition to the type of approach, the prognostic value of Patients characteristics variables with regard to the incidence of paraesthesias was assessed. Methods: Thirty patients scheduled for surgery under epidural anaesthesia were randomly assigned to one of two groups of 15 patients each. Epidural anaesthesia was performed via a midline or paramedian approach using loss of resistance to saline. Variables measured were: time needed to identify the epidural space, time needed for and ease of epidural catheter insertion and the incidence of paraesthesias. After completion of these observations, epidural anaesthesia was established with 150 mg ropivacaine 1%. Efficacy of the epidural block was assessed by the need for intraoperative analgesics and by the patient on a three-point scale (good/fair/poor). Results: Quality of sensory blockade was adequate in both groups. Catheter insertion was significantly faster using the paramedian approach. The difference between the two approaches with regard to the incidence of paraesthesias was not significant, however, there was a trend towards more paraesthesias in the midline group. In the multivariate analysis, type of approach was an independent significant predictor of paraesthesias and we found a trend towards a higher incidence of paraesthesias in female patients. Conclusions: Catheter insertion was faster in the paramedian group and we found a trend towards a higher incidence of paraesthesias with the midline approach.

Summary

Background and objectives: The sustained attention to response task (SART) test is a sensitive indicator of deficits in sustained attention and is simple to perform. Sustained attention is impaired for a short period after minor surgery under general anaesthesia but the magnitude and duration of this effect after major surgery is unknown. We used the SART test to investigate deficits in sustained attention in patients undergoing major surgery under general anaesthesia. Methods: The SART test was completed before surgery and at 24, 48 and 72 h postoperatively by 20 ASA I–II female patients (mean age 48.6 yr) undergoing total abdominal hysterectomy under general anaesthesia. It was also completed by 20 age-matched female controls at similar time intervals to evaluate the effect of repeated test performance. Results: There was a significant (P < 0.05) interaction between the groups in number of errors made (a measure of sustained attention deficit). The number of errors decreased in control subjects on repeated performance of the SART test but remained unchanged in patients undergoing total abdominal hysterectomy. The differences between groups remained significant after 72 h (P < 0.05). Patients' overall response times slowed significantly at 24–48 h (P < 0.05), but this recovered by 72 h after surgery. In contrast, overall response times in the control group tended to accelerate on repeated performance of the SART. Conclusions: The results of this study suggest that 72 h following major surgery patients have deficits in sustained attention compared with controls. Control subjects demonstrated a marked learning effect on repeated test performance compared with patients.

Summary

Background and objective: Sedation is commonly used to facilitate diagnostic procedures in children. The aim of our study was to investigate sedation in children using propofol alone or combined with fentanyl or midazolam with regard to efficacy, adverse reactions or side-effects related to the drugs, ease of operation for the endoscopist, and time to discharge from the post-anaesthesia care unit. Methods: We prospectively studied 240 children, aged 1–12 yr of age, undergoing endoscopic procedures of the upper gastrointestinal tract. The patients were given an oral premedication with midazolam (0.5 mg kg−1) and were then randomly allocated to one of the three study groups: propofol alone (Group P), propofol with fentanyl 1 μg kg−1 (Group PF) or propofol with midazolam 0.1 mg kg−1 (Group PM). Additional doses of propofol given during the procedure were recorded. Adequacy of sedation and ease of procedure (easy, adequate, impossible) were evaluated by the endoscopist, who was blinded as to the drugs used. Results: The duration of the procedure and the recovery period were similar in the three groups. The number of patients requiring supplemental doses of propofol to permit safe completion of gastroscopy was 31 in Group P (=39%; eight of these required two additional doses), 14 in Group PM (=18%), and 11 in Group PF (=13%) (P < 0.05). There was a lower incidence of adverse events in Group PM and in Group PF than in Group P (P < 0.05). Conclusions: Propofol in combination with fentanyl or midazolam gives better sedation and ease of endoscopy than propofol alone.

Summary

Background and objective: The aim of this study was to assess target-controlled propofol infusion as a technique of sedation for shoulder surgery under interscalene brachial plexus block in the sitting position and to evaluate the effect of sedation on hypotensive/bradycardic events during this procedure. Methods: One hundred and forty patients undergoing elective shoulder surgery in the sitting position under interscalene brachial plexus block (with 30 mL of ropivacaine 0.75%) were prospectively enrolled. All patients were premedicated with hydroxyzine 1 mg kg−1, none received beta-blockers. No patients were given atropine except for the patients who experienced a vasovagal event either during the block procedure or intravenous catheter placement. The target-controlled propofol infusion was started immediately after positioning the patient on the operating table. The initial target concentration was 1 μg mL−1. The infusion rate was adjusted every 15 min by increasing or decreasing the target concentration by 0.2 μg mL−1 steps to maintain the patient rousable to verbal commands (score of 3 on Wilson sedation scale). The following parameters were assessed: minimal, maximal, optimal target concentration, respiratory and haemodynamic parameters, total propofol dose, additional alfentanil needs, occurrence of hypotensive/bradycardic events, complications. Results are mean ± SD. Statistical analysis used t-test and χ2-tests. Results: The optimal propofol target concentration was 0.8 μg mL−1. No respiratory complications or conversion to general anaesthesia was reported. Two patients experienced transient and inconsequential intraoperative agitation. The incidence of hypotensive/bradycardic events during the procedure was 5.7% (eight patients). Conclusion: Target-controlled propofol infusion (0.8–0.9 μg mL−1) following hydroxyzine premedication is a safe and effective technique for sedation when combined with interscalene brachial plexus block during shoulder surgery in the sitting position.

Summary

Background and objective: The target effect-site concentration of propofol to insert a laryngeal mask airway was recently reported as almost 5 μg mL−1. The present study aimed to determine the target effect-site concentration with target-controlled infusion of propofol to place classical larnygeal mask airway or current laryngeal tube in adult patients. Methods: We included 40 patients scheduled for short gynaecological and radiological procedures under general anaesthesia in a randomized, double-blind manner using the Dixon's up-and-down statistical method. Monitoring included standard cardiorespiratory monitors, and bispectral index monitoring was used for all patients. Anaesthesia was conducted with a target-controlled infusion system: Diprifusor™. The initial target plasma concentration of propofol was 5 μg mL−1, and was changed stepwise by 0.5 μg mL−1 increments according to Dixon's up-and-down method. Criteria for acceptable insertion were: Muzi's score ≤2, and mean arterial blood pressure, heart rate or bispectral index variation <20% the baseline values.Results: Target effect-site concentration of propofol required to insert laryngeal tube was 6.3 ± 0.3 μg mL−1 with Dixon method and ED50 was 6.1 μg mL−1 (5.9–6.4) with logistic regression method. In the case of larnygeal mask airway they were 7.3 ± 0.2 μg mL−1 (Dixon method) and 7.3 μg mL−1 (7.1–7.5; with logistic regression) respectively (P < 0.05). ED95 (logistic regression) was 6.8 μg mL−1 (5.9–7.6) for laryngeal tube and 7.7 μg mL−1 (7.3–8.0) for larnygeal mask airway (P < 0.05). Haemodynamic incidents were 55% in the larnygeal mask airway group vs. 30% in the laryngeal tube group (P < 0.05). Conclusions: The target effect-site concentration of propofol for insertion of laryngeal tube was lower than for larnygeal mask airway (P < 0.05), with a consequent reduction of the propofol induced haemodynamic side-effects.

Summary

Background and objective: The aim of this study was to evaluate prostate anaesthetic block for haemodynamic tolerance and quality of analgesia during and after transurethral surgery. Methods: Ninety adult males, ASA III/IV, were randomly assigned to receive a prostate anaesthetic block (n = 45) or spinal anaesthesia (n = 45). The main outcome measurement during anaesthesia, surgery and recovery was haemodynamic tolerance (number of hypotensive episodes, heart rate, systolic and mean blood pressures). Other outcome variables were pain scores during anaesthesia, surgery and every 4 h until 24 h after the end of surgery and amount of oral morphine required during the 24-h postoperative period. Results: Sixty-six patients were ASA III and 24 ASA IV. Ongoing cardiovascular therapies were comparable between groups. All surgical procedures were performed under good conditions. For patients receiving prostate anaesthetic block, the blood pressure and heart rate did not change significantly during the study period. For patients receiving spinal anaesthesia, the hypotension rate was 55.6% (n = 25) compared to 0 in the prostate anaesthetic block group (P < 0.001); 25 and 4 patients, respectively, required vascular filling and additional ephedrine administration. In both groups, all pain scores were <40 (100 mm visual analogue scale) during the study period. Oral morphine was given during the postoperative period to two prostate anaesthetic block patients and four who had received spinal anaesthesia (not significant). Conclusion: Transurethral surgery under prostate anaesthetic block is safe and assures adequate analgesia during and after surgery.

Summary

Background and objective: The aim of this study was to assess postoperative patients' self-evaluation after xenon anaesthesia compared to total intravenous anaesthesia with propofol. Methods: 160 patients aged 18–60 yr, ASA I–II undergoing elective surgery took part in this randomised-controlled trial. After approval by the local Ethics Committee and as soon as the patients had given their written informed consent, they were randomly allocated to either the xenon (n = 80) or propofol (n = 80) group. In both groups remifentanil was used as opioid. The postoperative patients' self-evaluation was assessed with a double-blind telephone poll. Early spatial orientation, patients' self-evaluation of anaesthesia, choice of the same anaesthesia for future operations and recall of uncomfortable feelings after anaesthesia were determined. Results: 116 Patients were analysed, 63 in the xenon and 53 in the propofol group. The two study groups were comparable with respect to age, weight, height, gender and ASA classification. The two groups indicated similar values in the early spatial orientation at the onset of recovery and thereafter. Patients' self-evaluation of anaesthesia with main emphasis at high marks and repetition of the same anaesthesia if necessary were similar in both groups. Recalls of uncomfortable feelings were comparable but not for postoperative pain and appetite/thirst which appeared with a significantly higher incidence in the xenon group. Conclusions: Patients' self-evaluation and memory of early spatial orientation following xenon anaesthesia are comparable to propofol.

Summary

Background and objective: The aim of this study was to investigate the effect of ketamine on the endocrine and lipid metabolic status of the renal-banded animals. Methods: Forty male rats were randomly divided into four groups. Group A served as control, Group B animals received ketamine intraperitoneally at a dose of 100 mg kg−1, Group C was submitted to 2-kidney 1-clip experimental hypertension and Group D received ketamine as above, as well as being submitted to renal artery clipping. Atrial natriuretic peptide, angiotensin II and free fatty acid concentrations were measured in serum. In addition, adipose tissue lipoprotein lipase activity and angiotensin II content were determined, while the left ventricular weight relative to body weight was used as a cardiac hypertrophy index. Results: In renal-banded rats (Groups C and D) serum atrial natriuretic peptide, free fatty acid and angiotensin II concentrations as well as ventricular weight were increased, while adipose tissue lipoprotein lipase activity was lower than in control animals (Groups A and B). Ketamine administration did not influence angiotensin II concentrations either in normal (Group B) or banded rats (Group D). Ketamine increased serum atrial natriuretic peptide and free fatty acid concentrations only in normal animals (Group B). It had no influence on adipose tissue lipoprotein lipase activity either in normal (Group B) or banded animals (Group D). Adipose angiotensin II content did not differ between the four groups. Conclusion: Ketamine increased the atrial natriuretic peptide and free fatty acid concentration in normal rats. In 2-kidney 1-clip animals, ketamine did not elicit an additional response of serum atrial natriuretic peptide or free fatty acids levels. Its contribution to these factors was not significant.

Summary

Background and objective: Clonidine, which is used for induction of sympatholysis and prevention or treatment of alcohol withdrawal in anaesthesia and intensive care medicine, may have deleterious effects on intestinal mucosal perfusion. This study was designed to investigate the effects of clonidine on intestinal perfusion and oxygenation. Methods: Following ethical approval 17 anaesthetized, and acutely instrumented pigs were randomly assigned to two groups: eight animals received intravenous clonidine (2 μg kg−1 bolus and 2 μg kg−1 h−1), nine animals served as a control group. Measurement points for systemic and regional haemodynamic and oxygenation parameters were 135 and 315 min after starting the clonidine application. Results: Clonidine elicited systemic haemodynamic changes (median [25–75th interquartile range]): heart rate (106 [91, 126] to 84 [71, 90] beats min−1) cardiac output (147 [123, 193] to 90 [87, 107] mL min−1 kg−1) and mean arterial pressure (77 [72, 93] to 69 [61, 78] mmHg) decreased. Despite systemic haemodynamic changes, the superior mesenteric artery blood flow did not change in the clonidine group. The vascular resistance of the superior mesenteric artery decreased. The small intestinal oxygen supply, the mucosal and the serosal tissue oxygen partial pressure did not change. Conclusions: Systemic sympatholysis induced by intravenously applied clonidine in addition to basic intravenous anaesthesia elicited a decrease in cardiac output and mean arterial pressure. However, regional macrohaemodynamic perfusion was maintained and intestinal oxygenation did not change. Clonidine does not impair intestinal mucosal and serosal oxygenation under physiological conditions.