Summary

Background and objective: The main purpose of this study was to investigate the effects of sensory (acupressure and acupuncture) and optical stimulation (Laserneedle® acupuncture) on electroencephalographic bispectral index, spectral edge frequency and a verbal sedation score.

Methods: Twenty-five healthy volunteers (mean age ± SD: 25.5 ± 4.0 yr) were investigated during the awake state. The acupuncture point Yintang and a placebo control point were stimulated. The study was performed as a randomized, controlled and partly blinded cross-over trial.

Results: Bispectral index and spectral edge frequency values both decreased significantly (P < 0.001) during acupressure on Yintang to values of 62.9 (minimum 35) ± 13.9 bispectral index and to 13.3 (minimum 2.9) ± 8.1 Hz (spectral edge frequency right) and 13.8 (minimum 2.7) ± 7.3 Hz (spectral edge frequency left), respectively. Bispectral index was also significantly (P < 0.05) affected by Laserneedle® acupuncture and acupressure on the control point but the changes were not clinically relevant, 95.4 ± 4 and 94.2 ± 4.8, respectively. All interventions significantly (Yintang: P < 0.001; control point: P < 0.012) reduced verbal sedation score.

Conclusions: The study highlights the electroencephalographic similarities of acupressure induced sedation and general anaesthesia as assessed by bispectral index and spectral edge frequency.

The mechanisms which lead to secondary brain damage following transient ischaemia are incompletely defined. As discussed in this hypothesis article, the events which lead to such damage could encompass (a) a perturbed membrane handling of calcium, leading to a slow, gradual increase in the free cytosolic calcium concentration (Ca2+i), with subsequent calcium overload of mitochondria, (b) a sustained reduction of protein synthesis which, in the long run, deprives cells of enzymes or trophic factors essential to their survival, or (c) the initiation of an inherent program for cell death.

Results obtained in ischaemia of brief to intermediate duration demonstrate that the ultimate cell death is heralded by a reduction in the respiratory capacity of isolated mitochondria. However, the results fail to demonstrate whether or not such a reduction precedes deterioration of the bioenergetic state which then precipitates cell death. Cyclosporin A (CsA) has recently been shown to dramatically improve the delayed CA1 damage following transient forebrain ischaemia. Since CsA is known to block a deleterious permeability transition (PT) in mitochondria from several tissues in response to calcium accumulation and oxidative stress, the results on CsA effects in forebrain ischaemia support a mitochondrial origin for the delayed cell death. Furthermore, comparisons with the effects of CsA and α-phenyl-N-tert-butyl nitrone (PBN) in thymocytes and other cells undergoing programmed cell death suggest that delayed neuronal damage occurs by a sequence of events akin to those leading to apoptotic cell death. However, whether cell death is apoptotic or necrotic may depend on the severity of the insult (and its duration). We speculate that the initial ischaemic transient leads to gradual mitochondrial calcium overload, the latter triggering a PT, and apoptotic or necrotic cell death.

Since similar results have been obtained in normoglycaemic animals subjected to ischaemia of intermediate duration, and in animals with preischaemic hyperglycaemia, it seems likely that both increased ischaemia duration and hyperglycaemia accelerate damage to mitochondria in the reperfusion period.

Recent results obtained in transient focal ischaemia of 2 h duration demonstrate that the free radical spin trap PBN reduces infarct size, even when given 1 or 3 h after the start of reperfusion, thus providing a second window of therapeutic possibility. A major effect of the drug is exerted on the recovery of energy metabolism of the tissue since it reduces a secondary deterioration in the bioenergetic state, occurring after 2–4 h of reperfusion. At least in part, the spin trap may exert its effect by reducing microvascular dysfunction caused by oedema and to adhesion of polymorphonuclear (PMN) leucocytes, which give rise to an inflammatory response mediated by cytokines, lipid mediators, or free radicals. This contention is supported by the reduction in focal ischaemic damage by antibodies to adhesion molecules for PMNs. However, it has now been found that the secondary deterioration of the bioenergetic state of core and penumbral tissues are mirrored by corresponding changes in the respiratory functions of isolated mitochondria, suggesting that, also in this type of ischaemia, the mitochondria suffer secondary damage. It is conceivable that a significant fraction of malfunctioning mitochondria emanate from microvascular tissue, explaining why antibodies to adhesion molecules mitigate the ischaemic lesions.

It is hypothesized that tissue dysoxia and O2 debt are major factors in the development and the propagation of multiple organ failure in critically ill patients. Dysoxia is the result of an abnormal relationship between O2 supply (DO2) and O2 demand and translates into increased anaerobic metabolism and tissue and blood lactate concentration. First-line therapeutic strategies used to avoid the development of an O2 debt involve correction of cardiac output, haemoglobin, and O2 saturation in order to increase DO2 above its critical value. They are not sufficient, however, to ensure appropriate end-organ perfusion and oxygenation. The adequacy of cardiac output towards tissue metabolic requirements may be appreciated by venous-to-arterial and gut mucosal-to-arterial PCO2 differences. This review details these strategies and discusses their usefulness in current practice.

Nucleoside analogue-induced lactic acidosis is an often fatal condition in patients with HIV. There is only one report of successful treatment with riboflavin. We describe a 30-year-old female with AIDS and nucleoside analogue-induced lactic acidosis that exacerbated shortly after introducing total parenteral nutrition and reversed within hours after the addition of thiamine. Successful treatment of nucleoside analogue-induced lactic acidosis with a high dose of thiamine supports the hypothesis that vitamin deficiency is an important cofactor in the development of this rare and unpredictable condition in patients with HIV. We suggest that high dose B-vitamins should be given to any patient presenting with lactic acidosis under nucleoside analogue treatment.

Summary

Background and objective: We compared the laryngeal mask airway (LMA™) and the laryngeal tube (LT®) with the newly introduced perilaryngeal airway (CobraPLA®, PLA) with regard to haemodynamic responses induced by airway insertion, clinical performance and occurrence of postoperative sore throat after short surgical procedures. Methods: After premedication, 90 ASA I–II patients awaiting short surgical procedures were randomized to receive, LMA, LT or PLA. Anaesthesia was induced with intravenous propofol (2.5 mg kg−1) and mivacurium (0.2 mg kg−1). Number of attempts, time of insertion of the device, any other unwanted effect, mean aterial pressure, heart rate, oxygen saturation and end-tidal carbon dioxide were recorded. At the end of surgery, the cuff of the device was immediately deflated and the airway device was removed. The device was examined and noted for the presence of visible blood. Patients were asked to rate their throat soreness, dysphonia and dysphagia 1 and 24 h postoperatively. Results: There were no differences in haemodynamic variables. Insertion times for the devices were similar (LMA: 20 ± 11 s, LT: 19 ± 14 s and PLA: 21 ± 12 s.) The success rates at first insertion were lower in the (LMA group (57%) when compared with the PLA (97%, P < 0.05). The number and type of airway interventions for achieving an effective airway were similar. When the airways were removed 50% of the PLA devices had positive blood traces, while only 17% of the LMA and LT devices had positive blood traces (P < 0.01). Fifty percent of the patients suffered from a sore throat in the PLA group, which was significantly higher than in the LMA and LT groups (P < 0.05). Conclusion: We conclude that haemodynamic, ventilation and oxygenation variables throughout the surgery were similar with, LMA, LT and PLA, but LT and PLA were easier to insert; LMA and LT caused less mucosal trauma.

Summary

Background and objective: Preoperative anxiety is a challenging concept in the preoperative care of patients. The hypothesis of this study was that the doctors are able to estimate their patients' preoperative anxiety. Methods: A prospective clinical trial was performed on 67 adult patients and 26 paired anaesthetists and surgeons. The patients filled out two separate visual analogue scales for anxiety for the planned anaesthesia and surgery. After that the ‘anxiety subscale’ of the Hospital Anxiety and Depression's Scale was completed and a list of fearsome items was presented as the patients were asked to choose two conditions they considered the most frightening. Finally the patients were asked to select one or more items from a list of things, which they considered likely to relieve their preoperative anxiety. Similarly, the participating doctors were asked to estimate their patients' anxiety, guess their fearful conditions and their anxiety-relieving requests. Results: Median scores for anxiety as estimated with visual analogue scales by anaesthetists, surgeons and patients for anaesthesia were 34, 36 and 6, respectively; and for surgery 53, 47 and 9, respectively. The anxiety subscale of the Hospital Anxiety and Depression's Scale 8.9 ± 4.2, 8.6 ± 4.6 and 6.5 ± 4.5 (mean ± SD), respectively. Doctors' scores were significantly higher than the patients' scores (P < 0.05). Thus, the anaesthetists and the surgeons were unable to estimate their patients anxiety on any of the scales used (Kendall's τ < 0.25; P < 0.05). The proportion of correct estimation of the fearsome items was 20% for both the anaesthetists and the surgeons. Conclusions: Both anaesthetists and surgeons overestimated their patients' preoperative anxiety by a wide margin and poorly predicted their patients' feared conditions and their desire for relief of anxiety.

Summary

Background and objective: Sevoflurane and propofol reduce the extent of necrosis and improve neurological outcome in rodent models of cerebral ischaemia and reperfusion. However, the effects of these anaesthetics on programmed cell death (apoptosis) are unclear. The present study investigates whether sevoflurane and propofol affect the expression of apoptosis-regulating proteins after cerebral ischaemia in rats.

Methods: Thirty-two fasted male Sprague–Dawley rats were tracheally intubated and the lungs were ventilated (isoflurane and N2O/O2 anaesthesia). After surgical preparation, the animals were randomly assigned to one of the following groups: control (n = 8): fentanyl intravenous (10 μg kg−1 bolus and 25 μg kg−1 h−1 infusion) with N2O/O2; sevoflurane (n = 8): 2.0% sevoflurane (end-tidal concentration) and O2/air; propofol (n = 8): 0.8–1.0 mg kg−1 min−1 propofol intravenous and O2/air; sham-operated (n = 8): 25 μg kg−1 h−1 fentanyl intravenous and N2O/O2, no cerebral ischaemia. Ischaemia (30 min) was induced by unilateral common carotid artery occlusion plus haemorrhagic hypotension to a mean arterial pressure of 30–35 mmHg. Four hours after cerebral ischaemia the brains were removed and the expression of apoptosis-regulating proteins (Bax, Bcl-2, p53, Mdm-2) was determined using immunofluorescence and Western-blot analyses.

Results: The expression of the pro-apoptotic protein Bax was greater in control animals than in sevoflurane or propofol anaesthetized rats and than in sham-operated animals. The concentrations of Bcl-2, p53 and Mdm-2 were not changed 4 h after cerebral ischaemia.

Conclusions: In addition to the anti-necrotic effects of sevoflurane and propofol, these anaesthetics also reduce the concentration of the apoptosis-inducing protein Bax as early as 4 h after ischaemia.

A prospective, double-blind, randomized, controlled study was undertaken to compare the perioperative analgesic and recovery characteristics of equipotent doses of tramadol, pethidine and nalbuphine (3.0 mg kg−1, 1.5 mg kg−1 and 0.3 mg kg−1 respectively) with placebo (saline 0.02 ml kg−1) given at induction of anaesthesia in 152 ASA I children and young adults undergoing tonsillo-adenoidectomy. Premedication (temazepam and diclofenac), induction and maintenance of anaesthesia (thiopentone, atracurium, nitrous oxide and isoflurane), with controlled ventilation, were standardized. Variables monitored were heart rate (HR) and systolic arterial pressure (SAP) during surgery, time to recovery of spontaneous respiration at the termination of anaesthesia and restlessness, time to awakening, sedation and emesis in the recovery unit. Increases in HR or SAP >33% of baseline during surgery were treated with esmolol 2.0 mg kg−1 intravenously (i.v.) and restlessness during recovery was treated with the same opioid i.v. given with anaesthesia, or pethidine i.v. in the placebo group. With placebo, there was a high requirement for esmolol during surgery and for pethidine in the recovery ward. Tramadol did not reduce the rate of intra-operative treatment with esmolol, but reduced the tramadol requirement during recovery (P<0.05). Pethidine and nalbuphine reduced the intra-operative esmolol requirement more significantly (P<0.025 and P<0.005 respectively) and the need for treatment during recovery with opioids (P<0.005 each). The time to recovery of spontaneous respiration at the end of anaesthesia was only delayed by pethidine. Other recovery variables were similar, except that restlessness–pain scores were reduced by tramadol (P<0.02), pethidine (P<0.005) and nalbuphine (P<0.005). These results suggest that pethidine 1.5 mg kg−1 and nalbuphine 0.3 mg kg−1 given with induction of anaesthesia provide better analgesia during and after tonsillo-adenoidectomy than does tramadol 3.0 mg kg−1. The delay to recovery of spontaneous respiration with pethidine suggests a greater safety profile of nalbuphine and tramadol.

Summary

Background and objective: To determine the optimal concentration of ropivacaine for bolus-only patient-controlled epidural labour analgesia, three different doses of ropivacaine were evaluated in comparison with bupivacaine in a double-blinded multicentre study.

Methods: Four hundred-and-fifty labouring parturients at term in three different academic institutions were randomized to four groups receiving bupivacaine 0.125% with sufentanil 0.75 μg mL−1, ropivacaine 0.125% or 0.175% with sufentanil 0.75 μg mL−1, or ropivacaine 0.2%. After an initial bolus of 10 mL of the study solution, and once visual analogue scores (VAS) were below 30 mm, patient-controlled epidural analgesia was initiated with a bolus of 4 mL, a lockout interval of 15 min and without a background infusion. Variables studied were the quality of analgesia, incidence of side-effects, the degree of motor blockade, and the mode of delivery.

Results: Bupivacaine 0.125% and ropivacaine 0.125% with sufentanil proved equally effective in providing labour analgesia without a difference in local anaesthetic consumption (48.6 ± 23 mg bupivacaine vs. 52.1 ± 38 mg ropivacaine), motor blockade or mode of delivery. Ropivacaine 0.175% plus sufentanil enhanced the quality of analgesia of the initial loading dose, whereas ropivacaine 0.2% without sufentanil increased the consumption of local anaesthetics (80.2 ± 34 mg; P < 0.05) and the degree of motor blockade.

Conclusion: Despite recent studies indicating that bupivacaine and ropivacaine may not be equipotent, both local anaesthetics provided equi-effective analgesia at equal doses without a difference in side-effects.

Summary

Background and objective: We have investigated the concentrations of epinephrine, norepinephrine, vasopressin and angiotensin converting enzyme activity to explore the role of these mediators in the neuroendocrine response to laryngoscopy and tracheal intubation. Methods: One hundred (50 male, 50 female) ASA I patients aged 20–50 yr (mean ± SEM; 35.59 ± 0.99) were included in the study. They were undergoing elective surgery under standard anaesthesia induction and maintenance using tracheal intubation. Plasma concentrations of epinephrine, norepinephrine and vasopressin as well as plasma angiotensin converting enzyme activity were determined at four time points, before (T1) and after (T2) induction, and 2 (T3) and 5 min (T4) after intubation. Blood pressure and heart rate were recorded at corresponding times to reveal if any correlation existed between haemodynamic parameters and neuroendocrine response. Results: Heart rate increased after induction and intubation (P < 0.05) and decreased significantly at T4 (P < 0.05). Systolic blood pressure decreased significantly (P < 0.05) after induction and increased slightly after intubation decreasing to below baseline value (P < 0.05) at T4. Diastolic blood pressure increased slightly after intubation and decreased significantly (P < 0.05) at T4. Plasma epinephrine and norepinephrine concentrations decreased after induction and increased at T3 and T4 without reaching significance. Vasopressin concentrations increased slightly at T2 and T3 and decreased significantly at T4 (P < 0.05). Angiotensin converting enzyme activity was unaffected when compared with baseline values. Conclusions: Blood pressure, heart rate, plasma epinephrine, norepinephrine and vasopressin concentrations increased slightly in response to laryngoscopy and intubation, all returning to or below baseline 5 min later with no change in angiotensin converting enzyme activity in normotensive patients.

Summary

Background: This study was designed to investigate the impact of patient age on propofol consumption and recovery time using a propofol–remifentanil anaesthetic standardized with Narcotrend™ EEG monitoring. The Narcotrend is a monitor for measuring the depth of anaesthesia based upon a six-letter classification from A (awake) to F (increasing burst suppression) including 14 substages.

Methods: In 200 patients scheduled for minor orthopaedic surgery Narcotrend EEG electrodes were positioned on the patient's forehead as recommended by the manufacturer. Anaesthesia was induced with remifentanil 0.4 μg kg−1 min−1 and 2 mg kg−1 propofol. Immediately after intubation remifentanil was reduced to a constant rate of 0.2 μg kg−1 min−1 whereas a propofol infusion was now started at 3 mg kg−1 h−1 and then adjusted accordingly to achieve a target Narcotrend stages of D0–2 indicating general anaesthesia. At the end of surgery the propofol and remifentanil infusions were stopped without tapering, the time to unstimulated opening of eyes was determined, and the propofol consumption (given as mg kg−1 h−1) was calculated from the total amount of infused propofol but without the induction bolus, from the actual body weight and the duration of propofol infusion. Furthermore, a linear regression analysis was applied for propofol consumption vs. age.

Results: The ages of the patients studied ranged from 16 to 83 yr old and patients were classified as ASA I–III. Propofol consumption significantly decreased with the patients' age: 30 yr of age or below the propofol consumption was calculated as 5.9 ± 1.7 mg kg−1 h−1, for 31–50 yr as 5.4 ± 1.8 mg kg−1 h−1, for 51–70 yr as 4.5 ± 1.7 mg kg−1 h−1 and above 70 yr as 3.5 ± 1.4 mg kg−1 h−1. Linear regression analysis revealed propofol (mg kg−1 h−1) = 9.136 − (0.0597 × age (yr)); R = 0.53. Concomitantly, the recovery time to opening of eyes increased with the patients' age: ≤30 yr, 7.4 ± 3.7 min; 31–50 yr, 9.5 ± 4.0 min; 51–70 yr, 9.8 ± 4.1 min; and ≥71 yr, 14.9 ± 12.1 min.

Conclusions: We conclude that with Narcotrend guidance, mean propofol consumption and recovery times are age dependent. However, as a result of large inter-individual variability, age per se does not allow a prediction of individual propofol need or recovery time.

Background and objective To assess retrospectively the complications and morbidity of electroconvulsive therapy.

Methods Complications occurring in 75 patients during 612 electroconvulsive therapy procedures under propofol anaesthesia were reviewed by data analysis.

Results At least one complication occurred in 51 patients (68%) during the course of their treatment. Among these complications, 12 were potentially life-threatening: one patient developed angina pectoris, another aspiration pneumopathy, there were two incidences of bronchospasm, three hypoxic episodes (SpO2 < 92% with FiO2 = 1) and five severe episodes of laryngospasm which caused hypoxia. Twenty-five patients (33%) were confused for more than 2 h after the electroconvulsive therapy. Confusion recurred in 10 patients (13%) after several sessions of electroconvulsive treatment. Six patients had a traumatic complication, with one requiring surgery.

Conclusion Our results, compared with other studies, suggest that electroconvulsive therapy is not a low-risk procedure, with a particularly high rate of respiratory complications that may have been previously overlooked. Therefore, ambulatory anaesthesia may not be appropriate on a regular basis for most of these patients.

Summary

Background: Propofol and dexmedetomidine are widely used for sedation in the intensive care unit yet there are limited data on its effects on gastric motility. In our preliminary study, we examined whether or not any effect of propofol and dexmedetomidine on gastric emptying is preserved in critically ill patients. Methods: Twenty-four critically ill, enterally fed adult patients each received enteral feeding via a nasogastric tube at 50 mL h−1 throughout the 5-h study period. Either propofol 2 mg kg−1 h−1 (n = 12, Group P) or dexmedetomidine 0.2 μg kg−1 h− (n = 12, Group D) was given intravenously over 5 h. Gastric motility was measured indirectly by analysis of the absorption over time of 1.5 g of paracetamol administered into the stomach at the start of the study period. At the beginning and end of the study, residual gastric volume and pH of residual gastric fluid were measured. Results: Gastric residual volume measured at the end of propofol infusion (19.33 ± 11.33) was found to be higher when compared with the volume measured before infusion (11.33 ± 4.84) and after dexmedetomidine infusion (9.17 ± 4.54). But, there was no difference between groups in gastric emptying time (AUC120 894.53 ± 499.39 vs. 1113.46 ± 598.09 propofol and dexmedetomidine groups, respectively). Conclusion: In our study, gastric residual volume measured at the end of propofol infusion was found to be higher when compared with the volume measured before infusion and after dexmedetomidine infusion. There was no difference between groups in gastric emptying time.

Gamma-hydroxybutyrate (GHB) may well be developed as an alternative for optional sedation during spinal anaesthesia. As in the case of propofol (PRO), GHB has good sedative properties associated with cardiovascular and respiratory stability. When used as a narcotic agent, recovery times are variable (e.g. > 30 min); in contrast, sedative dosages, as used in intensive care patients (e.g. 10–20 mg kg−1 h−1), result in adequate clinical recovery. The goal of the present study was to compare the clinical properties of GHB and PRO after continuous administration during spinal anaesthesia (SPA). Thirty patients (ASA I and II) received either GHB (n=15) or PRO (n=15) at random. Patients refusing sedation (n=15) received 0.9% saline (control). At eight defined time points, haemodynamic (BP, HR), respiratory (RR, RMV, Pao2, Spo2, Peto2, Petco2, ̇Vo2, ̇Vco2) and endocrinological parameters (plasma concentrations of noradrenaline and adrenaline) as well as the clinical side-effects were assessed simultaneously. With both sedatives, the desired level of sedation was achieved. Recovery times ranged between 1.7±0.9 min with PRO and 6.1±4.9 min with GHB. GHB provided stable haemodynamic conditions without clinically relevant respiratory depression. In contrast, PRO caused a decrease in mean arterial pressue (MAP) of 15%, whereas respiratory minute volume was decreased by 53% (with periods of apnoea, Spo2<90%). ̇Vo2 and ̇Vco2 correlated with respiratory minute volume (GHB, PRO, control). Plasma noradrenaline and adrenaline concentrations remained nearly constant in the GHB and control groups and declined during sedation with PRO. Both GHB and PRO are suitable for optional sedation during spinal anaesthesia. Control and recovery are acceptable for clinical purposes. It seems that GHB and PRO have similar haemodynamic, respiratory and endocrinological characteristics. Therefore, GHB may serve as an alternative for the established management of continuous sedation during SPA with PRO.

Summary

Background and objective: Extremity surgery with tourniquet to provide a bloodless field may be a good human model for ischaemia reperfusion (IR) injury. The aim of this study was to investigate the effects of three different modes of propofol use on tourniquet induced IR injury in lower extremity operations. Methods: Thirty-three consecutive ASA Grade I and II patients were randomized into three groups of 11 patients each. In the spinal group (Group S), after intrathecal anaesthesia, sedation was given with a propofol infusion at 2 mg kg−1 h−1 after a 0.2 mg kg−1 bolus dose and fentanyl 100 μg. In the general (Group G) and TIVA (Group T) groups, general anaesthesia was induced with propofol 2 mg kg−1 with fentanyl 100 μg and maintained with inhalation of halothane or infusion of propofol respectively. Venous blood samples were obtained at different time points for measurements of plasma malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels. Results: Plasma MDA levels were increased significantly in the Group G at 1 min before tourniquet release and 5 and 20 min after tourniquet release compared with before induction of general anaesthesia (baseline). Before intrathecal anaesthesia and before induction of general anaesthesia significantly decreased levels of MDA were observed both before and after tourniquet release compared to baseline. Plasma SOD and CAT concentrations were decreased significantly only at tourniquet release in the Group G compared with baseline. In the Groups S and T these enzymes were not changed significantly. Plasma GPx levels were not altered in any groups. Conclusion: Propofol administration may inhibit lipid peroxidation and restore antioxidant enzyme levels in extremity surgery requiring tourniquet application.