Summary

Background and objective: To evaluate the capability of first responders to achieve and maintain normal ventilation of the lungs of victims employing a bag-valve device and two oxygen-driven resuscitators.

Methods: Prospective, controlled, blinded, single-centre clinical trial using a bag-valve device and one of two FR-300® devices, with 20 cmH2O working pressure, and flows of either 24 or 30L min−1. One hundred and four patients were analysed. Induction of anaesthesia followed by ventilation of the lungs with a bag-valve device and an Oxylator® in manual and automatic modes performed by a fireman first responder. Each series was repeated for three conditions (anaesthesia; anaesthesia plus muscle relaxation, both with facemask; anaesthesia plus relaxation using an endotracheal tube).

Results: Patients age 49 ± 17 yr; 47% males, 48–132 kg. Normocapnia was achieved and maintained in 66% (bag-valve device), 82% (Oxylator®).

Conclusions: The use of an oxygen-driven device improves the ability of first responders to achieve and maintain normocapnia even when distracted. Use of the Oxylators® improves performance (P < 0.001) vs. the bag-valve device significantly.

Summary

Background and objective: To investigate the effects of moderate hyponatraemia, induced by intravenous application of an electrolyte-free irrigation fluid, as a model of the human transurethral prostate resection syndrome and of its rapid correction by hypertonic saline infusion in rats.

Methods: Experimental animals received irrigation fluid (Purisole SM®) 20 mL kg−1 body weight, intravenously. In one group, hyponatraemia was subsequently rapidly corrected by infusion of hypertonic saline (NaCl 5.85%), while rats of group two were ‘sham-corrected’ by infusion of a balanced salt crystalloid solution. Plasma sodium concentrations were analysed during and at the end of the experiments. After 10 days, experimental and untreated control animals were killed humanely, fixed by perfusion and the brains were prepared for electron microscopic investigation of myelin sheets and glial cell numbers in the striatum and pons.

Results: The myelin appearance was unaltered in experimental groups compared to controls, but glial cell numbers were distinctly altered in the pons but not in the striatum. In the pons, oligodendrocytes were significantly reduced in number upon rapid correction of hyponatraemia, while astrocyte numbers were increased in rats with uncorrected hyponatraemia.

Conclusions: Our electron microscopic data demonstrate that the effects of hyponatraemia and of its rapid correction are multifarious in animals. This may also apply for human patients during transurethral prostate resection.

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.

The intubating laryngeal mask airway is a modification of the conventional laryngeal mask and is used as a tool for difficult intubation. It can be inserted without placing the head and neck in the Magill position and has been used successfully in cervical spine injuries. Reported is a case of successful insertion of the intubating laryngeal mask and subsequent intubation through it in a patient with ankylosing spondylitis with cervical involvement resulting in a fixed flexion deformity who underwent coronary artery bypass grafting.

Ischaemia reperfusion injury is a common and important phenomenon that occurs predictably in patients undergoing such procedures as cardiopulmonary bypass, thrombolysis, surgery under tourniquet, organ transplantation or embolectomy. Oxidative stress and the resulting lipid peroxidation play a major role in reperfusion injury. Membrane and cellular dysfunction result and, subsequently, organ injury or failure may ensue. Traditional methods of quantifying ischaemia reperfusion injury, including measurement of malondialdehyde, lack specificity and sensitivity. It was reported in 1990 that isoprostanes, a series of prostaglandin-like compounds, are produced by the free radical-catalyzed peroxidation of arachidonic acid. Measurement of the isoprostane concentration in urine or plasma provides the most reliable, non-invasive method currently available to assess oxidative stress in vivo. Serial measurement of isoprostanes in biological fluids has enhanced our understanding of the mechanisms underlying ischaemia reperfusion injury itself and its role in certain diseases. Furthermore, measurement of the isoprostane concentration provides a means to assess the effects of prophylactic and therapeutic interventions. In the future, the development of rapid, simple assays for isoprostanes offers the potential to assess prognosis during and after ischaemia reperfusion events.

Summary

Background and objective: Morbidity from subarachnoid haemorrhage is common and results from complications including myocardial dysfunction and neurogenic pulmonary oedema causing hypotension and hypoxia – both major causes of secondary brain injury. Predicting patients at risk of developing these complications may facilitate early intervention.

Methods: Using QTc dispersion to assess repolarization inhomogeneity, patients who had suffered severe acute subarachnoid haemorrhage were studied in an intensive care unit. Electrocardiograms were recorded within 24 h of ictus. Subsequent development of myocardial dysfunction was defined as a requirement for inotropes, and neurogenic pulmonary oedema as a PaO2 (kPa)/FiO2 ratio <40. Together they constituted cardiorespiratory compromise.

Results: Twenty-seven patients were recruited. QTc dispersion was greater in patients (74.1 ms, SD ± 26.1) than in controls (48.3 ms, 12.0) P < 0.0001, 95% CI 14.6, 37.0. Thirteen patients developed cardiorespiratory compromise and had greater QTc dispersion (84.5 ms, 26.2) than patients who did not develop cardiorespiratory compromise (64.5 ms, 22.7) P = 0.046, 95% CI 0.3, 39.6. There was no difference in QTc dispersion between patients who did and those who did not develop myocardial dysfunction alone. Similarly, there was no difference in QTc dispersion between patients who did and those who did not develop neurogenic pulmonary oedema alone.

Conclusions: Increased QTc dispersion is associated with the later development of cardiorespiratory compromise in poor-grade subarachnoid haemorrhage patients. QTc dispersion may be used as a marker to predict impending clinical deterioration, providing an opportunity for early intervention.

Summary

Background and objectives: Salt-water aspiration results in pulmonary oedema and hypoxia. We tested the hypothesis that partial liquid ventilation has beneficial effects on gas exchange and rate of survival in acute and extended salt water-induced lung injury. Methods: Anaesthetized, ventilated rats (tidal volume 6 mL kg−1, PEEP 5 cmH2O) received a tracheal salt-water instillation (3%, 8 mL kg−1 body weight) and were randomly assigned to three groups (n = 10 per group). While lungs of Group 1 were gas-ventilated, lungs of Group 2 received a single perfluorocarbon instillation (30 min after the injury, 5 mL kg−1 perfluorocarbon) and lungs of Group 3 received an additional continuous perfluorocarbon application into the treachea (5 mL kg−1 h−1). Arterial blood gases were measured with an intravascular blood gas sensor. Results: Salt-water instillation resulted in a marked decrease in PaO2 values within 30 min (from 432 ± 65 to 83 ± 40 mmHg, FiO2 = 1.0, P < 0.01). Arterial oxygenation improved in all three groups irrespective of treatment. We observed no significant differences between groups in peak PaO2 and PaCO2 values. Conclusions: Our results suggest that partial liquid ventilation has no additional beneficial effects on gas exchange after life-threatening salt water-induced lung injury when compared to conventional gas ventilation with positive end-expiratory pressure.

Summary

Background and objective: The development of acute renal failure (ARF) in critically ill patients is associated with an increase in hospital mortality. Recently, it was shown that starting renal replacement therapy early and using high-filtrate flow rates can improve the outcome, but this could not be confirmed in later investigations. Studying selected patient subgroups could provide a useful basis for patient selection in future trials evaluating the outcome of renal replacement therapies. We, therefore, investigated the impact of the underlying disease on the outcome of patients with ARF.

Methods: We retrospectively analysed 306 patients with ARF who were treated with renal replacement therapy. Patients were classified according to six initial diagnosis groups: haemorrhagic shock, post-cardiac surgery, post-liver transplantation, trauma, severe sepsis and miscellaneous. Univariate and multivariate multiple logistic regression analysis was used to determine which factors influenced the outcome.

Results: Underlying disease proved to be the only independent risk factor for mortality that was present at intensive care unit (ICU) admission (P = 0.047). Patients with severe sepsis had a significantly higher mortality rate (68%) than ARF patients as a whole (51%) (P = 0.02). Length of stay in the ICU, the use of catecholamines, the delay before ARF onset, and the correlation between APACHE II score and ICU length of stay proved to be additional independent predictors of outcome.

Conclusions: Patient selection and subgroup definition according to the underlying disease could augment the usefulness of future trials evaluating the outcome of ARF.

We investigated the effects of controlled hypotension with haemodilution under isoflurane anaesthesia on splanchnic perfusion in elderly patients. We determined the intramucosal pH using gastric tonometry in 28 patients scheduled for hip surgery. Patients without cardiac disease were assigned to two groups according to age. Group A (adult patients, n=14) included patients aged less than 60 years (range 29–58 years, 47±11 years, mean±SD) and group B(elderly patients, n=14) more than 65 years (68–78 years, 72±5 years). Anaesthesia was maintained with N2O-O2-isoflurane. After induction of anaesthesia, haemodilution was produced by drawing 800–1000 mL of blood and replacing it with the same amount of hydroxyethyl starch. Final haematocrit values were 23–24% in all groups. Controlled hypotension was induced with prostaglandin E1 (PGE1) and mean blood pressure was maintained at approximately 60 mmHg for approximately 80 min. Measurements, including gastric intramucosal pH (pHi), arterial blood pH (pHa) and serum lactate were measured before haemodilution (T0), after haemodilution (T1), 80 min after starting hypotension (T2), 60 min after recovery from hypotension (T3) and on the 1st post-operative day (T4). The values of pHa and lactate showed no change in the groups throughout the time course. The gastric pHi values showed significant decreases from 7.418±0.035 to 7.334±0.024 (P < 0.05) in group A and from 7.428±0.029 to 7.320±0.039 (P < 0.05) in group B after haemodilution, while no further decreases were found at 80 min after starting the hypotension (7.329±0.038 in group A and 7.322±0.031 in group B) and 60 min after recovery from hypotension (7.331±0.029 in group A and 7.328±0.034 in group B). It can be concluded that moderate haemodilution under isoflurane anaesthesia might impair splanchnic perfusion in adult and elderly patients. The addition of controlled hypotension with PGE1 or an increase in age did not further impair splanchnic perfusion nor the splanchnic oxygen supply.

After an intubating dose of rocuronium satisfactory intubating conditions are achieved before the onset time at the adductor pollicis. We examined the possibility that measurement of the relaxation of the masseter muscle is a more appropriate guide when determining the intubating time. Simultaneous accelerometry with a 0.1-Hz single twitch stimulation of the chin and thumb was performed in 20 patients after 0.6 mg kg=1 rocuronium. We observed a significantly more brief mean lag time and onset time at the masseter muscle (22.5 and 61 vs. 32.5 and 160 s). The corresponding mean relaxation at the onset time was also significantly more pronounced at the masseter muscle (99.6 vs. 97.6%). A mean onset time at the masseter muscle of 61 s as produced by rocuronium corresponds clinically with excellent or good intubating conditions. From these results, we suggest that measurement of the onset time of muscle relaxation at the masseter muscle appears to be a better predictor of good intubating conditions than measurements made using the adductor pollicis muscle after administration of rocuronium.

Summary

Background and objective: The bispectral index, a parameter derived from the electroencephalograph, has been shown to correlate with the loss of consciousness and sedation. This study was designed to assess the effects of bispectral index monitoring on sevoflurane and its recovery profiles.

Methods: Sixty ASA I and II patients undergoing open abdominal surgery were randomized into two groups: one monitored using the bispectral index (Group BIS) and the other without its use (controls). After a standardized induction, anaesthesia was maintained with sevoflurane in both groups. In Group BIS, sevoflurane was titrated to maintain the bispectral index in the range 40–60. In the control group, the administered sevoflurane concentration was adjusted according to the signs of anaesthesia. The end-tidal sevoflurane concentration, bispectral index and routine haemodynamic variables were noted every 5 min during surgery. The consumption of sevoflurane was computed. At the conclusion of surgery operations, the time to ‘open eyes on verbal command’, ‘motor response to verbal command’ and Aldrete's score were recorded by a blinded anaesthesiologist.

Results: The difference in the consumption of sevoflurane was not significant between the groups. Bispectral index monitoring was associated with a reduction of 4.73% in sevoflurane usage and 2.19 mL h−1 was saved.

Conclusions: Bispectral index monitoring during anaesthesia provides only a small advantage related to the need to monitor the depth of anaesthesia.