Summary

Background: The aim of this prospective study was to compare continuous cardiac output measurements of the non-invasive cardiac output system (NICO) with the pulmonary artery catheter during off-pump coronary bypass surgery. Methods: Twenty-two patients enrolled for off-pump coronary surgery received both a pulmonary artery catheter and a non-invasive cardiac output system for measurement of cardiac output. Data were compared by the Bland–Altman method to calculate the degree of agreement and to analyse if a significant difference existed between the two methods of cardiac output measurements. Results: Perioperatively, the non-invasive cardiac output underestimated cardiac output, but postoperatively overestimated it. The limits of agreement were larger during surgery compared to the postoperative period (−3.1; +2.5 vs. −1.4; +2.2 L min−1). Perioperatively, cardiac output measured with the pulmonary artery catheter varied from 0.5 to 7.5 L min−1 (mean 3.6 L min−1) and with the non-invasive cardiac output from 0.5 to 8.4 L min−1 (mean 3.9 L min−1). Postoperatively, these were 2.5–7.7 L min−1 (mean 4.5 L min−1) and 2.3–8.4 L min−1 (mean 4.9 L min−1), respectively. Conclusion: During off-pump cardiac surgery, the non-invasive cardiac output reliably measures cardiac output and does it more rapidly than a pulmonary artery catheter and may be more useful in order to detect rapid haemodynamic changes.

Summary

Background and objective:Only regular training of anaesthetic personnel ensures safe and reliable application of cricoid pressure during rapid sequence induction of anaesthesia. Previously described training devices are either complicated, too expensive and usually unavailable, or they are very simple and do not correctly simulate the process of applying cricoid force. We designed and tested a cricoid pressure trainer with real-time display of applied force. The device is easy to assemble at relatively little cost with material widely available. It allows effective biofeedback training of the force required during the Sellick manoeuvre and can be used for routine staff assessment.

Methods:Thirty-six anaesthesia assistants were assessed for their correct application of cricoid pressure. Previous training in, and knowledge of, applying cricoid pressure was first evaluated by a questionnaire. We designed a model for testing the application of cricoid force. Pre-training cricoid forces were obtained by asking the subjects to apply ‘awake’ (10 N = 1.020 kg) and ‘asleep’ (30 N = 3.060 kg) cricoid pressure on our model while blinded to the actual pressure produced. The volunteer was then trained to apply correct pressure employing real-time biofeedback. Post-training values were later determined with the subject again blinded to the actual applied pressure.

Results:Post-training performance showed significant improvement in the application of the correct cricoid force (P<0.0005). Only 8% (3/36) of subjects applied incorrect ‘awake’ cricoid pressure after training vs. 56% (20/36) before training. All participants applied correct ‘asleep’ cricoid pressure after training vs. 72% (26/36) failing before training.

Conclusions:Our biofeedback cricoid pressure trainer is effective in the assessment and training of correct cricoid pressure application by anaesthetic personnel.

Summary

Background and objective: Enteral acetaminophen (paracetamol) has limited analgesic efficacy due to its delayed absorption and sub-therapeutic plasma concentration. Intravenous (i.v.) acetaminophen solves this issue and could thus provide adequate analgesia as a single agent. We compared intraoperative i.v. acetaminophen with intramuscular (i.m.) meperidine with regard to postoperative analgesia and readiness for discharge in paediatric patients undergoing day care dental restoration. Methods: Forty children were randomized, in this double-blind study, to receive acetaminophen 15 mg kg−1 i.v. (Group A) or meperidine 1 mg kg−1 i.m. (Group M) after anaesthesia induction and before surgery. All patients received midazolam 0.5 mg kg−1 orally 30 min preoperatively and fentanyl 1 μg kg−1 i.v. immediately after induction. Anaesthesia was induced with either sevoflurane inhalation or propofol 3 mg kg−1 i.v. and was maintained with sevoflurane. Postoperatively, the objective pain scale, Ramsay sedation score, and Aldrete score were determined every 5 min until readiness for recovery room discharge (defined as achieving an Aldrete score of 10). Results: Group A had slightly higher pain scores during early recovery compared with Group M (estimated marginal means: 3 ± SEM 0.4 vs. 2 ± SEM 0.4, respectively (95% CI for difference: 0.4, 2.6), P = 0.012 for F-test). In contrast, Ramsay scores were higher in Group M than in Group A during assessment period (estimated marginal means: 4 ± SEM 0.3 vs. 2 ± SEM 0.4, respectively (95% CI for difference: −2.3, −0.3), P = 0.013 for F-test). Group A patients achieved an Aldrete score of 10 sooner than those in Group M (5 ± SEM 2 vs. 16 ± SEM 4 min, respectively (95% CI for difference: −9, −14), P = 0.009). Conclusion: Compared with i.m. meperidine, intraoperative i.v. acetaminophen resulted in slightly higher pain scores but earlier readiness for recovery room discharge in paediatric patients undergoing dental restoration. The potential economic benefit of early recovery room discharge needs to be further explored.

Summary

Background and objectives: Failed endotracheal intubation is a principal cause of morbidity and mortality in anesthetized patients. The aim of this study was to investigate the efficiency of lateral neck radiography in predicting difficult intubation. Methods: In a prospective triple-blind study, 100 patients (aged 18–89 yr), scheduled for elective surgery were randomly selected. Lateral neck X-ray was obtained from each of the patients before operation. Several angles and parameters on the X-ray were proposed to illustrate a relationship with easy or difficult intubation. A radiologist recorded these angles before the operation. An anaesthesiologist also determined the Mallampati score preoperation. At the time of intubation, two other anesthesiologists performed a laryngoscopy and, according to established criteria, identified the patients as easy or difficult intubation. The results were then compared with each other. Results: Fifteen patients were identified as having difficult intubation (laryngoscopy Grades III and IV). Sensitivity and specificity of the Mallampati Class test were 26% and 100%, respectively. The sensitivity and specificity of the lateral neck X-ray for three measured angles were 100%. The positive and negative predictive values (NPVs) for those angles were 100% and for Mallampati classification were 100% and 80%, respectively. Conclusions: Compared to the Mallampati Class test, our method of analyzing the lateral X-ray, although not as easy and universally applicable as Mallampati Class test, proved to be a suitable method for predicting difficult intubation.

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: This study was performed to compare three disposable airway devices, the LMA Unique (LMA-U), the Ambu laryngeal mask (Ambu LM) and the Soft Seal laryngeal mask (Soft Seal LM) for elective general anaesthesia during controlled ventilation in non-paralysed patients. Methods: One hundred and twenty ASA I–III patients scheduled for routine minor obstetric surgery were randomly allocated to the LMA-U (n = 40), Ambu LM (n = 40) or Soft Seal LM (n = 40) groups, respectively. Patients were comparable with respect to weight and airway characteristics. A size 4 LMA was used in all patients and inserted by a single experienced anaesthesiologist. Oxygenation, overall success rate, insertion time, cuff pressure and resulting airway leak pressure were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness. Results: Time of insertion was shortest with the Ambu LM, while failure rates were comparable with the LMA-U, the Ambu LM and the Soft Seal LM (median 19 s; range 8–57 s; success rate 100% vs. 14; 8–35; 97% vs. 20; 12–46; 95%). Insertion was judged ‘excellent’ in 75% of patients in the LMA-U group, in 70% of patients in Ambu LM group and in 65% of patients in the Soft Seal LM group. There was no difference between devices with respect to postoperative airway morbidity at 6 h or 24 h following surgery. Conclusions: All three disposable devices were clinically suitable with respect to insertion times, success rates, oxygenation, airway and leak pressures, as well as to subjective handling and postoperative airway morbidity.

Summary

Background and objective: The intravenous anaesthetic propofol has been reported to exert neuroprotective actions by several mechanisms. This study has been designed to investigate the effects of propofol on intracellular calcium increase in cultured cerebrocortical neurons after exposure to pathological concentrations of N-methyl-d-aspartate (NMDA) mediated by potential direct interactions of propofol with NMDA receptors.

Methods: The effects of propofol (0.1–100 μmol) on intracellular calcium increase induced by 300 μmol NMDA (180 s) were measured in cultured cerebrocortical neurons using the calcium-sensitive fluorochrome calcium green-5N-acetoxymethylester with confocal laser scanning microscopy.

Results: The intraneuronal calcium increase after exposure to 300 μmol NMDA depended on extracellular calcium concentration. Propofol reduced the increase of NMDA receptor-induced intraneuronal calcium concentration dependently with a threshold concentration for a significant effect of 10 μmol. The overall effect was small, since even high concentrations of propofol (100 μmol) diminished intraneuronal calcium rise by only 50%.

Conclusions: The threshold concentration for significant effects of propofol on the NMDA-induced increase of intraneuronal calcium turned out to be in the upper limit of propofol concentrations that are considered to be clinically relevant. However, in the presence of high propofol concentrations, inhibition of NMDA receptor-mediated calcium increase might contribute to neuroprotective effects observed with propofol.

The expansion of the European Union during the last 2 yr has resulted in the need for a revision of existing guidelines to further harmonize education and training in the specialty of anaesthesiology throughout the European Union. Although each individual country is responsible for its own training and certification, these guidelines are intended to reflect minimum criteria for specialist training. It is the opinion of the Section and Board of Anaesthesia that specialist training will need to be for a minimum of 5 yr.

Summary

Background and objective: The aim of this study was to test the efficacy of positive end-expiratory pressure (PEEP) to the dependent lung during one-lung ventilation, taking into consideration underlying lung function in order to select responders to PEEP.

Methods: Forty-six patients undergoing open-chest thoracic surgical procedures were studied in an operating room of a university hospital. Patients were randomized to receive zero end-expiratory pressure (ZEEP) or 10 cmH2O of PEEP to the dependent lung during one-lung ventilation in lateral decubitus. The patients were stratified according to preoperative forced expiratory volume in 1 s (FEV1) as an indicator of lung function (below or above 72%). Oxygenation was measured in the supine position, in the lateral decubitus with an open chest, and after 20 min of ZEEP or PEEP. The respiratory system pressure–volume curve of the dependent hemithorax was measured in supine and open-chest lateral decubitus positions with a super-syringe.

Results: Application of 10 cmH2O of PEEP resulted in a significant increase in PaO2 (P < 0.05). This did not occur in ZEEP group, considered as a time matched control. PEEP improved oxygenation only in patients with high FEV1 (from 11.6 ± 4.8 to 15.3 ± 7.1 kPa, P < 0.05). There was no significant change in the low FEV1 group. Dependent hemithorax compliance decreased in lateral decubitus, more in patients with high FEV1 (P < 0.05). PEEP improved compliance to a greater extent in patients with high FEV1 (from 33.6 ± 3.6 to 48.4 ± 3.9 mL cmH2O−1, P < 0.05).

Conclusions: During one-lung ventilation in lateral decubitus, PEEP applied to the dependent lung significantly improves oxygenation and respiratory mechanics in patients with rather normal lungs as assessed by high FEV1.

Summary

Background and objective: A randomized controlled trial of patients undergoing laparoscopic cholecystectomy. To evaluate whether the instillation of levobupivacaine, with epinephrine, intraperitoneally, reduces morphine consumption; further, to consider the degree of abdominal and shoulder pain in the presence of local anaesthetic at the site of surgical incision.

Methods: Patients received a standardized procedure and were allocated randomly to receive either (a) 2.5 mg mL−1 levobupivacaine 30 mL, with epinephrine 5 μg mL−1, or (b) normal saline 30 mL, with epinephrine 5 μg mL−1, to the bed of the gall bladder and above the liver, immediately before wound closure.

Results: Median (interquartile range) total abdominal pain during inspiration in the levobupivacaine group was significantly (P = 0.041) lower (71 (21–129) mm) than that in the placebo group (123 (71–179) mm). However, there was no significant difference between the two groups with respect to total abdominal pain at rest, right shoulder pain or the consumption of rescue morphine and rescue dihydrocodeine. There were no differences between the two groups with respect to the administration of cyclizine, total nausea and total sedation scores. In addition, the number of episodes of vomiting was not significantly different.

Conclusions: Intraperitoneal administration of levobupivacaine with epinephrine is associated with modest analgesia following laparoscopic cholecystectomy.

Summary

Background and objective: This randomized, double-blinded clinical study was designed to compare the efficacy and safety of remifentanil and morphine administered using intravenous (i.v.) patient-controlled analgesia (PCA) for postoperative analgesia after major abdominal surgery during the first 24 postoperative hours.

Methods: Sixty-nine patients were randomly allocated into two groups, each receiving remifentanil or morphine. The first group received i.v. remifentanil PCA with a loading dose of 45 μg, a maintenance dose of 1 μg min−1, a bolus dose of 15 μg and a lockout interval of 10 min during the first 24 postoperative hours. The second group received i.v. morphine PCA with a loading dose of 5 mg, a maintenance dose of 0.3 mg h−1, a bolus dose of 1 mg and a lockout interval of 15 min. Age, weight, sex, history of general anaesthesia, duration of surgery and time spent in the post-anaesthesia care unit were recorded. Preoperative pulse rate, systolic and diastolic blood pressures (BP), respiration rate and arterial blood gases were collected. Pulmonary function was tested before induction of anaesthesia, as well as at 4 and 26 h after operation. Pulse rate, systolic and diastolic BP, respiration rate, arterial blood gases, sedation and visual analogue scores, and presence of side-effects in the recovery room and on the ward for 24 h were recorded at 0, 1, 2, 4, 6, 12, 18 and 24 h after operation. Total drug use, number of boluses delivered, number of boluses demanded and delivery/demand ratio were collected.

Results: Sixty patients were evaluated. The groups did not differ in age, weight, sex, history of general anaesthesia, duration of surgery or time spent in the recovery unit. There were also no clinically relevant differences between the groups with regard to haemodynamic and respiratory parameters as well as sedation and visual analogue scores (P > 0.05). More bolus doses were demanded and delivered and the delivery/demand ratio was significantly higher in the remifentanil group (P < 0.05). There was no finding suggesting acute opioid tolerance during remifentanil or morphine PCA.

Conclusion: The i.v. remifentanil PCA with the chosen dosage regimen after abdominal surgery produces postoperative analgesia and has cardiovascular side-effects similar to those achieved with i.v. morphine. Special attention must be given to respiratory depression during establishment of PCA with remifentanil.

Follow-up studies on individuals who suffer severe head injury give a picture of poor cognitive and psychosocial outcome. However, recent evidence suggests that with the passage of time, many individuals make adjustments that compensate for early disability, leading to a reduction in social handicap with a corresponding improvement in life quality and personal satisfaction. This article will attempt to briefly review the main sources of evidence contributing to long-term outcome following serious head trauma.

Summary

Background and objective: There is a controversy regarding the best drug for prevention of nausea and vomiting in patients receiving intrathecal morphine. The aim of this study was to examine efficacy and tolerability of droperidol compared with ondansetron for the prevention of morphine-induced nausea and vomiting. Methods: In a randomized, placebo-controlled trial, 120 women undergoing Caesarean section under spinal anaesthesia with intrathecal morphine 0.1 mg received intravenous ondansetron 4 mg (n = 40), droperidol 1.25 mg (n = 40) or saline (n = 40) immediately after umbilical-cord clamping. Nausea and vomiting were graded according to intensity at 1, 2, 4, 6, 12 and 24 h. Results: Nausea or vomiting occurred in 14 patients (35%) in the placebo group, 4 (10%) in the ondansetron group and 10 (25%) in the droperidol group; the difference between ondansetron and placebo was statistically significant (P = 0.007). Eleven of the 14 placebo patients (27.5%) vomited, compared with none of the 4 ondansetron patients (vs. placebo, P = 0.0004) and 5 of the droperidol patients (vs. placebo, P = 0.18). Three of the 14 placebo patients (7.5%) were nauseous, compared with 4 (10%) receiving ondansetron and 5 (12.5%) receiving droperidol. Conclusions: Ondansetron was effective in reducing the incidence of nausea and vomiting in patients receiving intrathecal morphine for Caesarean section.

Background and objective: The feasibility of monitoring measured intravascular volumes and the cardiac filling pressures were compared to reflect the optimal volume status of postoperative patients.

Methods: In a prospective clinical study, 14 hypovolaemic adult patients were included after cardiac surgery. All patients received 1000 mL hydroxyethyl starch after meeting the authors’ criteria for hypovolaemia. Pressures were measured by use of a pulmonary artery catheter and volumes were determined by double-indicator dilution technique.

Results: Stroke volume index (SVI), central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP), intrathoracic blood volume index (ITBVI) and total circulating blood volume (TBVIcirc) increased significantly after volume loading (30.7 ± 9.8 to 41.7 ± 9.6 mL m−2, 4.9 ± 1.7 to 9.1 ± 2.3 mmHg, 6.6 ± 1.3 to 10.6 ± 1.9 mmHg, 858 ± 255 to 965 ± 163 mL m−2, and 1806 ± 502 to 2110 ± 537 mL m−2, respectively). During the subsequent 1 h steady-state period, CVP and PAOP decreased significantly (9.1 ± 2.2 to 7.4 ± 2.2 mmHg and 10.6 ± 1.9 to 9.2 ± 2.0 mmHg, respectively), whereas SVI and intravascular volumes remained unchanged. The changes of CVP and PAOP did not correlate with changes in stroke volume during volume loading (r2 = 0.06 and 0.03, respectively) and during steady-state (r2 = 0.17 and 0.00 respectively). On the other hand, a significant correlation was found between changes of the intrathoracic blood volume and changes in stroke volume during the volume loading (r2 = 0.67) and also during the steady-state phase (r2 = 0.83).

Conclusions: Intrathoracic blood volume reflects more accurately the preload dependency of cardiac output in postoperative patients than left/right-sided cardiac filling pressures.

Summary

Background and objective: To investigate the clinical application of a mathematical model of pulmonary gas exchange, which ascribes hypoxaemia to shunt and ventilation/perfusion mismatch. Ventilation/perfusion mismatch is quantified by ΔPO2, which is the drop in oxygen pressure from alveoli to lung capillaries. Shunt and ΔPO2 were used to describe changes in oxygenation after coronary artery bypass grafting.

Methods: Fourteen patients were studied 2–4 h after surgery and on postoperative days 2, 3 and 7. On each occasion inspired oxygen fraction was changed in four to six steps to obtain arterial oxygen saturation (SaO2) in the range of 90–100%, enabling construction of FeO2/SaO2 curves. Measurements of ventilation, circulation and oxygenation were entered in a previously described mathematical model of pulmonary gas exchange.

Results: We found that oxygenation was most impaired 3 days after surgery. By fitting the mathematical model to the FeO2/SaO2 curve, we found that shunt remained constant throughout the study period. However, ΔPO2 increased from 0.5 kPa (median, range 0–3.8) 2–4 h after surgery, to 3.2 kPa (range 1.2–6.4, P < 0.05) on day 2, and to 4.0 kPa (range 1.2–8.3) on day 3. On day 7, ΔPO2 decreased to 2.2 kPa (range 0–3.5, P < 0.05).

Conclusions: Ventilation/perfusion mismatch (ΔPO2), rather than shunt, explains the changes in postoperative oxygenation. The model of pulmonary gas exchange may serve as a useful and potentially non-invasive clinical tool for monitoring patients at risk of postoperative hypoxaemia.