Summary

Chronic thromboembolic pulmonary hypertension is a condition that is recognised in an increased percentage of patients. Pulmonary endarterectomy is recognised as being the only curative option for a subgroup of those patients, but anaesthesiologists and intensivists face many challenges in how they manage these patients perioperatively. Ultimately, it is the combination of skills in a multidisciplinary team that leads to a successful procedure and dramatically improves patient's quality of life and life expectancy.

Summary

Background and objective: The haemodynamic effects of acute pulmonary hypertension can be largely attributed to ventricular interdependence during diastole. However, there is evidence that the two ventricles also interact during systole. The aim of the present study was to examine the effects of acute pulmonary hypertension on both components of left ventricular systole, i.e. contraction and relaxation, using load-independent indices. Methods: Ten pigs were instrumented with biventricular conductance catheters, a pulmonary artery flow probe and a high-fidelity pulmonary pressure catheter. Haemodynamic measurements were performed in baseline conditions and during stable pulmonary vasoconstriction induced by the thromboxane analogue U46619. Contractility was quantified using the end-systolic pressure–volume and preload recruitable stroke work relationships. The τ-end-systolic pressure relationship was used to assess load-dependency of relaxation. Results: Acute pulmonary hypertension caused a decrease in the slope of the left ventricular preload recruitable stroke work relationship (from 6.64 ± 1.7 to 5.19 ± 1.9, mean ± SD; P < 0.05), a rightward shift of the end-systolic pressure–volume relationship (P < 0.05), and an increase in the slope of the τ-end-systolic pressure relationship (from −0.15 ± 0.5 to 0.35 ± 0.17; P < 0.05). The diastolic chamber stiffness constant of both ventricles increased during pulmonary hypertension (P < 0.05). Conclusions: In the present model, acute pulmonary hypertension impairs left ventricular contractile function and relaxing properties. The present study provides additional evidence that, besides the well-known diastolic ventricular cross talk, systolic ventricular interaction may play a significant role in the haemodynamic consequences of acute pulmonary hypertension.

Summary

Background and objective: High-dose opioid anaesthesia contributes to decreasing metabolic and hormonal stress responses in patients undergoing cardiac surgery. However, the increase in context-sensitive half-life of opioids given as a high-dose regimen can affect postoperative respiratory recovery. In contrast, remifentanil can be given in high doses without prolonging context-sensitive half-life due to its rapid metabolism. Therefore, we performed a prospective, randomized trial to compare anaesthesia consisting of propofol/remifentanil or propofol/sufentanil with regard to postoperative respiratory function and outcome. Methods: Patients undergoing coronary artery bypass grafting were randomized to a propofol/remifentanil (0.5–1.0 μg kg−1 min−1) or propofol/sufentanil (30–40 ng kg−1 min−1) based anaesthetic. Carbon dioxide response, forced expiratory volume in one second, vital capacity, and functional residual capacity were measured 1 day prior to the operation, 1 h before extubation, 1, 24 and 72 h after extubation. In addition, the incidence of atelectasis, pulmonary infiltrates, intensive care unit and postoperative length of stay were compared. Patients and physicians were blinded to the treatment group. Results: Twenty-five patients in each treatment group completed the study. There was no difference between patients of the treatment groups regarding demographics, risk- or pain scores. In all patients, carbon dioxide response, forced expiratory volume in one second, vital capacity and functional residual capacity were decreased postoperatively compared to baseline. Patients randomized to remifentanil had less depression of carbon dioxide response, less atelectasis and shorter postoperative length of stay (12 d vs. 10 d) than after sufentanil (P < 0.05). Conclusions: Intraoperative use of high-dose remifentanil for coronary artery bypass grafting may be associated with improved recovery of pulmonary function and shorter postoperative hospital length of stay than sufentanil.

Summary

Background and objectives: Ischaemic preconditioning is commonly regarded as one of the most powerful protective mechanisms against a subsequent lethal ischaemic injury during coronary artery bypass graft surgery but is not practiced routinely. Experimentally, isoflurane, a commonly used volatile anaesthetic agent, provides myocardial protection through a signal transduction cascade that is remarkably similar to the pathways identified in ischaemic preconditioning. The aim of our study was to investigate whether pre-ischaemic administration of isoflurane exerted protection against prolonged ischaemia with functional recovery and reduced necrosis among patients undergoing coronary artery bypass graft surgery. Methods: Forty patients scheduled for elective coronary artery bypass graft operations were prospectively randomized into the control or isoflurane groups. In the isoflurane group, isoflurane 2.5 minimum alveolar concentration was administered for 15 min followed by a 5-min washout period before aortic cross-clamping. The control group received a time-matched period of isoflurane-free cardiopulmonary bypass. The conduction of anaesthesia and surgery were standardized in all patients. Haemodynamic data, troponin I release and inotropic support were measured and recorded perioperatively. Results: There were no adverse effects related to isoflurane administration. In the isoflurane group, the mean cardiac index after cardiopulmonary bypass was significantly higher than the pre-bypass value (P < 0.05), whereas no difference was found in the control group. At 15 min after cardiopulmonary bypass and 6 h after surgery, the changes in cardiac index and stroke volume index were significantly higher in the isoflurane group than in the control group (P < 0.05). There was a consistently lower release of troponin I in the isoflurane group compared to the control group. Compared to the controls, the mean troponin I level was significantly reduced in the isoflurane group at 24 h after surgery (P = 0.042). Conclusions: The present results support the preconditioning effect of isoflurane in patients undergoing coronary artery bypass graft surgery as clinically feasible and providing optimal cardiac protection.

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: In the perivascular sheath of the brachial plexus, the volume of anaesthetic solution determines the quality of anaesthetic cover. Fibrous septa may divide the perivascular space into compartments, leading to inadequate diffusion of the anaesthetic solution. The aim of our study was to obtain good anaesthesia and less complications using high volume of low concentration anaesthetic solution, overcoming the obstacle of the septa with a double approach to the scalene sheath. Methods: Sixty patients scheduled for shoulder capsuloplasty received both Winnie interscalene brachial plexus block and Pippa proximal cranial needle approach. The patients were randomly assigned to two groups. A constant dose of local anaesthetic was administered to each group: Group I (30 patients) received high volume (60 mL of anaesthetic solution) and Group II (30 patients) received low volume of solution (30 mL of anaesthetic solution). Sensory and motor block in the upper limb and complications were evaluated. Results: In all the patients the quality of anaesthesia obtained at the surgical site was excellent. In Group I also the areas supplied by the medial cutaneous nerves of the arm and forearm, ulnar, median and radial nerves were blocked (P < 0.002). Complications were only observed in Group II and consisted of bradycardia and hypotension (66% of the patients) and phrenic nerve paresis (27% of the patients). Conclusions: The lower concentration of the anaesthetic solution avoids complications while increased volume provides good analgesic cover. The combination of the Winnie interscalene plexus block and the Pippa proximal cranial needle approach should contribute to fill up the scalene sheath overcoming the septa obstacles.

Summary

Background and objective: To evaluate the effects of sevoflurane and desflurane in combination with intravenous remifentanil on time for discharge from the postanaesthesia care unit and need for postanaesthesia care unit management after elective laparoscopic cholecystectomy. Methods: 231 ASA Grade I–II patients, undergoing elective laparoscopic cholecystectomy in seven University teaching hospital, were randomly allocated to receive a desflurane–remifentanil (n = 105) or sevoflurane–remifentanil (n = 126) anaesthetic. A blinded observer recorded times for emergence and postanaesthesia care unit discharge (achievement of an Aldrete score ≥9), number of patients eligible for postanaesthesia care unit discharge when exiting the operating room and occurrence of adverse events. Results: Intraoperative cardiovascular stability was similar in the two groups. Emergence, response and extubation occurred earlier after desflurane (5.4 ± 3 min, 5.5 ± 3 min and 7.5 ± 4 min) than sevoflurane (6.6 ± 3.5 min, 7.2 ± 4 min and 9.1 ± 4.2 min) (P = 0.0005, 0.05 and 0.003, respectively). Postanaesthesia care unit bypass was possible in 44 desflurane–remifentanil patients (41%) and 55 sevoflurane– remifenatnil patients (43%) (P = 0.69), while postanaesthesia care unit discharge occurred after 46 min (25th–75th percentiles: 18–40 min) with desflurane and 64 min (25th–75th percentiles: 20–50 min) with sevoflurane (P = 0.04). Postoperative nausea and vomiting was observed in 40 desflurane–remifentanil patients (36%) and 53 sevoflurane–remifentanil patients (42%) (P = 0.42). Conclusions: Both the desflurane–remifentanil and sevoflurane–remifentanil combinations provide a similarly adequate intraoperative cardiovascular stability. Emergence and postanaesthesia care unit discharge were faster with desflurane–remifentanil than sevoflurane–remifentanil, but this was not associated with a larger proportion of postanaesthesia care unit bypass, confirming that no clinically relevant differences are present between the two agents.

Summary

Background and objective: A prospective crossover randomized trial was conducted to compare the performance of three commonly used anaesthetic facemasks: a clear plastic ‘Anaesthetic Facemask’ with pre-inflated air cushion, no inflation valve, and for single use (Intersurgical Limited, Wokingham, UK), a clear plastic ‘Air Cushion Mask’ with inflatable air cushion and inflation valve, and for single use (Proact Medical Limited, Kettering, UK), and a black antistatic reusable rubber facemask with pre-inflated air cushion, and no inflation valve (Datex Ohmeda Limited, Hatfield, UK). Methods: After local Ethics Committee approval, written consent was taken from 60 ASA 1 or 2 patients undergoing elective ENT procedures. Following routine intravenous anaesthetic induction and muscle relaxation, a Guedel's oropharyngeal airway was inserted and each of the facemasks tried in a crossover fashion. The degree of chest expansion, the feel on the reservoir bag, the degree of leak around the mask and the overall satisfaction of the anaesthetist were graded and recorded for each facemask. Results: Both the plastic facemasks performed similarly in all the four criteria. The antistatic rubber facemask performed significantly better than the plastic facemasks in these criteria (P < 0.05). Conclusions: This study has shown that the antistatic rubber facemask outperformed the two plastic facemasks during routine induction of general anaesthesia. We hope this will encourage manufacturers to improve disposable facemask design to simulate the antistatic rubber facemask.

Summary

Backgrounds: Microglial cells play an important role in the pathophysiology of intracerebral haemorrhage. We have examined the possible influence of sevoflurane on the reactivity of microglial cells during intracranial haemorrhage. Methods: Forty adult male rats were divided into two groups. All animals were anaesthetized with fentanyl, dehydrobenzperidol and midazolam. In the experimental group animals additionally received sevoflurane 2.2 vol% end-tidal concentration. Intracranial haemorrhage was produced through infusion of blood into the striatum. The microglial cell population (numerical density of immunoreactive cells and their distribution) was assessed on days 1, 3, 7, 14 and 21 after producing a haematoma using antibodies OX42 and OX6. Results: In the control group significant differences in the density of OX42-ir cells between 3rd and 7th (81.86 vs. 129.99) (95% CI: −77.99 to −18.25, P = 0.0035) and between 14th and 21st (105.36 vs. 63.81) (95% CI: 13.21 to 69.89, P = 0.006) survival days were observed. However, significant increase of percentage of amoeboid OX42-ir cells between 3rd and 7th (0.98 vs. 48.71) (95% CI: −52.17 to −43.30, P = 0.0001) and between 7th and 14th (48.71 vs. 58.47) (95% CI: −13.96 to −5.55, P = 0.0002) and then their decrease – between 14th and 21st (58.47 vs. 31.74) (95% CI: 22.52 to 30.93, P = 0.0001) days of observation were noted. In the sevoflurane groups OX42-ir cells were not found. On the 3rd day the density of OX6-ir cells in the sevoflurane group was significantly lower than that in the control group (12.39 vs. 34.57) (95% CI: −49.78 to −2.96, P = 0.02). The percentage of an amoeboid form of OX6-ir cells was significantly lower in the sevoflurane group than that in the control group (27.31 vs. 82.03) (95% CI: −72.52 to −36.92, P = 0.0001) (58.76 vs. 82.37) (95% CI: −38.81 to −8.41, P = 0.003) (42.87 vs. 81.55) (95% CI: −53.23 to −24.10, P = 0.0001) respectively for 3rd, 7th and 14th days of survival. Conclusion: Administration of sevoflurane during anaesthesia in animals with intracerebral haemorrhage evoked a decrease of activation of the microglial cells.

Summary

Background and objective: Anaesthesia information management systems, though still not used widely, will inevitably replace handwritten records and may eventually serve as a core for the development of computerized decision support. We investigated staff expectations and the accuracy of data entry in a recently implemented commercially available anaesthesia information management system. Methods: A structured questionnaire was administered to the staff before and 1 week and 3 months after implementation in order to assess their opinion. The quality of manual data entry, and of automatic data record was evaluated by looking for missing data and the prevalence of artefacts. Results: Despite initial fears the users quickly accepted the system. Both automatic and manual data entry were found to be accurate and reliable while the prevalence of artefacts was relatively low. Conclusions: A commercially available anaesthesia information management system can be easily implemented and used instead of paper charts.