Objectives: To conduct a systematic review of the evidence for the effectiveness of five visual electrodiagnostic tests to inform the Medical Services Advisory Committee (MSAC) of the Department of Health and Ageing (Australia) in its decision in allocating public funding for new technologies.

Methods: We searched the biomedical literature to identify English-language articles published from 1966 to September 2000. We assessed validity of methodology of included studies against the following criteria: investigators (i) compared test with an appropriate reference test; (ii) tested an appropriate spectrum of patients; (iii) masked assessment of study and reference tests; (iv) measured the study test independently of clinical information; and (v) measured the reference test before any interventions.

Results: Sixty-one articles met inclusion criteria for critical appraisal: nineteen were cross-sectional studies that compared a study test with another test, thirty-four were case-control studies that compared a test in a group of patients with an eye disease to a group of subjects without eye disease, and eight studies were case series. None of the included studies met all of the validity criteria. Only four studies provided enough information to calculate diagnostic characteristics but were flawed due to inclusion of patients already diagnosed with disease or lack of an appropriate reference test and, thus, overestimated test accuracy.

Conclusions: Identified studies did not provide sufficient valid evidence of the clinical value of the five visual tests in diagnosing diseases of the retina or optic nerve. Thus, MSAC recommended that the tests not be supported by public funding.

Background and objective: Liver transplantation is characterized by several changes in intravascular blood volume due to vasodilatation based on neurohumoral mediators, intraoperative bleeding and anaesthesia technique effects. Today, with the transpulmonary indicator dilution technique, cardiac index (CIart) can be evaluated and preload assessed in terms of the intrathoracic blood volume index (ITBVI). The aim was to analyse in patients undergoing liver transplantation two preload variables, pulmonary artery occlusion pressure (PAOP) and ITBVI with respect to cardiac index (CIpa) and stroke volume index (SVIpa), the correlation between ITBVI and PAOP, and secondary the relationship between the changes (Δ) of ITBVI and PAOP and the changes of CIpa and SVIpa, and the relationships between ΔITBVI and ΔPAOP. The reproducibility and precision of all CIart and CIpa measurements were also evaluated.

Methods: A prospective study was performed in 60 patients monitored with a pulmonary artery catheter and with the PiCCO® system. The variables were evaluated with a linear regression model.

Results: Linear regression analysis between ITBVI-CIpa and ITBVI-SVIpa were r2 = 0.47 (P < 0.0001) and r2 = 0.55 (P < 0.0001) respectively, while PAOP poorly correlated to CIpa (r2 = 0.02), SVIpa (r2 = 0.015) and ITBVI (r2 = 0.002). Only changes in ITBVI were correlated with changes in CIpa (Δ1, r2 = 0.37; Δ2, r2 = 0.32), and SVIpa (Δ1, r2 = 0.60; Δ2, r2 = 0.47). The mean bias between CIart and CIpa was 0.13 L min−1 m−2 (2 SD = 1.04 L min−1m−2) (r2 = 0.86, P < 0.0001).

Conclusions: In comparison with PAOP, ITBVI seems a more reliable indicator of cardiac preload in patients undergoing liver transplantation.

Background and objective: Previous studies have shown that general anaesthetic agents modulate the production of hypothalamic prostaglandins (PG) D2 and E2, which are mediators of sleep and wakefulness respectively. Although flurbiprofen, a cyclo-oxygenase inhibitor, is used clinically as a non-steroidal anti-inflammatory agent and postoperative analgesic, it reduces prostaglandin production. Thus, this agent may affect the depth of sedation during general anaesthesia. In this study, we examined if flurbiprofen affects the bispectral index, which correlates with sedation levels.

Methods: Fifteen patients who underwent elective surgery under total intravenous anaesthesia with propofol and fentanyl were studied. The sedation level was monitored using a bispectral index monitor. On attainment of stable haemodynamics and a bispectral index, patients were given flurbiprofen axetil 50 mg intravenously. A bispectral index and 95% spectral edge frequency were recorded before and 5, 10, 15, 20 and 30 min after flurbiprofen axetil intravenously.

Results: Bispectral indexes of 51.7 (95% CI: 47.3–56.8), 51.7 (47.1–56.3), 51.3 (46.3–56.3), 50.3 (45.8–54.2), 48.9 (43.6–54.1) and 50.3 (45.5–55.2) at 0, 5, 10, 15, 20, 30 min after flurbiprofen axetil intravenously were observed. There was no change in this or 95% spectral edge frequency.

Conclusions: Clinical dose of flurbiprofen axetil does not alter the bispectral index and 95% spectral edge frequency under total intravenous anaesthesia with propofol and fentanyl.

Background and objective: Clinical sedation assessment becomes insufficient in deeply sedated patients. Bispectral index as a processed electroencephalogram parameter provides a continuous and observer-independent value reported to change with sedation. The aim of this prospective observational study was to determine the reliability and possible confounding factors of the bispectral index to assess sedation in surgical intensive care patients.

Methods: Following major surgery, bispectral index, body temperature and electromyographic activity of 44 ventilated patients were recorded. Sedation levels were assessed with Ramsay sedation score.

Results: Although bispectral index correlated with Ramsay sedation score (-0.64; P < 0.01) we found that in deeply sedated patients temperature instability and electromyographic activity increased bispectral index. Bispectral index correlated significantly with electromyographic activity (0.80; P < 0.01) and with an increase of body temperature (0.55; P < 0.01) not only in all patients but also in clinically deeply sedated patients (0.57; P < 0.01 and 0.46; P < 0.05).

Conclusions: Only under certain conditions, such as low muscular activity and body temperature stability, may the bispectral index be a useful addition to clinical scoring in the sedation assessment of critically ill patients.

Background and objective In recent studies, ultrasonic diagnostic imaging has proved useful in the screening of the trajectory of the epidural needle. With regard to possible side-effects of spinal and epidural anaesthesia caused by vessel injury, we aimed to evaluate the usability of Colour Doppler imaging for the depiction of interspinous vessels in prepuncture examination.

Methods Ultrasonic examination of the L¾ interspace area was performed in 20 volunteers. Using a 4-MHz and a 7-MHz probe with B-mode and Colour Doppler imaging, respectively, we compared four settings for the quality of vessel depiction in the puncture area. Overall resolution was evaluated according to the distinction of landmarks. Vascular structures were identified by pulsation (B-mode) or blood flow (Doppler).

Results Colour Doppler imaging of the L3/4 interspace was unachievable using the 7-MHz transducer. Vessel detection was possible in 50% of the B-mode images and in all of the 4-MHz Doppler images. Vessels were perceptible from a diameter of 0.5 mm. Veins were the predominantly visible structures. Overall vessel visibility was best using 4-MHz Colour Doppler.

Conclusions Prepuncture Doppler imaging can provide the epiduralist with information regarding the position of vessels in the needle trajectory. This might help to reduce complications in regional anaesthesia.

Background and objective The recently developed transcerebral double-indicator dilution technique has proven to be a feasible monitoring alternative to measure global cerebral blood flow at the bedside. However, the short-term repeatability of transcerebral double-indicator dilution measurements has not yet been investigated. The present study was designed to investigate the accuracy in terms of reliability for repeated transcerebral double-indicator dilution measurements to assess global cerebral blood flow during a definite carbon dioxide challenge in a clinical trial.

Methods The investigation was performed in 10 patients scheduled for elective coronary artery bypass grafting. After induction of anaesthesia, repeated cerebral blood flow measurements using transcerebral double-indicator dilution were performed during target normocapnia, hypocapnia and hypercapnia. For transcerebral double-indicator dilution measurements, a bolus injection of ice-cold indocyanine green was administered into a central vein. The resulting thermal dye dilution curves were recorded simultaneously in the aorta and the jugular bulb using combined fibreoptic thermistor catheters. Cerebral blood flow was calculated from the mean transit times of the indicators through the brain. Additionally, transcranial Doppler sonography was simultaneously performed to measure transient changes in the cerebral blood flow velocity.

Results Transcerebral double-indicator dilution measurements revealed a reasonable coefficient of repeatability with 9.1, 9.7 and 20.2 mL min−1100 g−1 during normo-, hypo- and hypercapnic conditions, respectively. However, a total of 20% of the administered measurements had to be rejected for methodological reasons.

Conclusions Repeated measurements with the transcerebral double-indicator dilution method show a reasonable repeatability. With consideration to the limitations of the transcerebral double-indicator dilution technique, this new method proves to be a reliable monitoring tool to measure global cerebral blood flow at the bedside.

Background and objective Laparoscopic and open surgery have been compared with conflicting results regarding their systemic responses. The sensitivity of biochemical markers that are used to discriminate between the stress responses to different types of surgery varies from study to study. We wanted to evaluate the stress response and the sensitivity of clinical and biochemical stress markers in patients undergoing laparoscopically assisted vaginal or abdominal hysterectomy.

Methods We performed a case-control study with patients undergoing laparoscopically assisted vaginal hysterectomy (n=20) or abdominal hysterectomy (n=20). Pain scores were assessed at rest and during coughing, and active leg elevation and fatigue scores using a visual analogue scale. In 10 patients of each group, haematocrit, white cell count, C-reactive protein, glucose, cortisol, adrenocorticotrophic hormone, β-endorphin immunoreactivity, interleukin-6 and urine excretion of epinephrine and norepinephrine were measured preoperatively and during the first 44 postoperative hours.

Results The most sensitive symptoms and markers of the systemic response were pain scores during mobilization, fatigue scores, C-reactive protein and interleukin-6 (P < 0.01 in all comparisons). Pain scores at rest, and all other laboratory markers of the systemic response, did not discriminate between the two types of surgery.

Conclusion Follow-up of postoperative pain scores during mobilization and fatigue levels might be an easy tool for the evaluation of postoperative recovery. Using an identical anaesthetic technique, the neuroendocrine response was of the same magnitude after both types of surgery.

Background and objective This study investigates the interaction of sevoflurane and nitrous oxide on EEG median power frequency of 2.5 Hz during surgery.

Methods Sevoflurane concentrations required for electroencephalographic median power frequency between 2 and 3 Hz were measured in 25 patients during gynaecological laparotomies. Nitrous oxide was randomly administered at 0, 20, 40, 60 and 75 vol%, subsequently two different concentrations in each patient. The data were analysed using isobolographic analysis together with previously published data on nitrous oxide-isoflurane, -enflurane, or -desflurane interaction.

Results The interaction is described by the equation: C volatile anaesthetic/C0 volatile anaesthetic + C N2O/C0 N2O = 1 (C is the concentrations for a drug combination to achieve the desired effect; C0 is the concentration for single drug use). The parameters are C0 isoflurane = 1.11 vol% (95% CI 1.03–1.19), C0 enflurane = 1.64 (1.52–1.77), C0 desflurane = 5.31 (4.92–5.73), C0 sevoflurane = 2.12 (1.96–2.29), C0 N2O = 174 (153–202). These parameters decrease by 6% (2.5–10) for every 10 years of patients’ age > 40 years.

Conclusions The interaction is compatible with additivity. The potency of nitrous oxide to substitute the volatile anaesthetics is less than anticipated from previously reported MAC values.

Background and objective Few and conflicting data are available regarding the changes of plasma potassium concentration during acute respiratory acidosis in human beings. This study compares the acute changes in plasma potassium concentration in acutely hypercapnic patients and in non–hypercapnic patients during general anaesthesia.

Methods Thirty-three patients undergoing interventional rigid bronchoscopy were studied. Ventilation of the lungs was randomly conducted using either spontaneous–assisted ventilation or intermittent negative–pressure ventilation. All patients received the same anaesthetic protocol. Arterial blood gases and osmolality, and plasma concentrations of glucose, sodium, potassium and chloride were measured.

Results Intraoperatively, PaCO2 was higher during spontaneous-assisted ventilation than during intermittent negative-pressure ventilation (9±1.8 vs. 5.4±1.2 kPa, P < 0.001) and the pH was also lower during spontaneous-assisted ventilation than during intermittent negative-pressure ventilation (7.24±0.07 vs. 7.4 ±0.08, P < 0.001). Plasma potassium concentration remained similar in both groups (3.8± 0.2mmolL−1 with spontaneous–assisted ventilation vs. 3.7± 0.4mmol L−1 with intermittent negativepressure ventilation).

Conclusion Acute respiratory acidosis does not affect plasma potassium concentration.

Background and objective We studied the influence of systemic (aortic) blood flow velocity on changes of cerebral blood flow velocity under isoflurane or sevoflurane anaesthesia.

Methods Forty patients (age: isoflurane 24–62 years; sevoflurane 24–61 years; ASA l–lll) requiring general anaesthesia undergoing routine spinal surgery were randomly assigned to either group. Cerebral blood flow velocity was measured in the middle cerebral artery by transcranial Doppler sonography (depth: 50–60 mm). Systemic blood flow velocity was determined by transthoracic Doppler sonography at the aortic valve. Heart rate, arterial pressure, arterial oxygen saturation and body temperature were monitored. After standardized anaesthesia induction (propofol, remifentanil, vecuronium) sevoflurane or isoflurane were used as single agent anaesthetics. Cerebral blood flow velocity and systemic blood flow velocity were measured in the awake patient (baseline) and repeated 5 min after reaching a steady state of inspira-tory and end-expiratory concentrations of 0.75, 1.00, nd 1.25 mean alveolar concentrations of either anaesthetic. To calculate the influence of systemic blood flow velocity on cerebral blood flow velocity, we defined the cerebral-systemic blood flow velocity index (CSvl). CSvl of 100% indicates a 1:1 relationship of changes of cerebral blood flow velocity and systemic blood flow velocity.

Results Isoflurane and sevoflurane reduced both cerebral blood flow velocity and systemic blood flow velocity. The CSvl decreased significantly at all three concentrations vs. 100% (isoflurane/sevoflurane: 0.75 MAC: 85 ± 25%/81 ± 23%, 1.0 MAC: 79 ± 19%/74 ± 16%, 1.25 MAC: 71 ± 16%/79 ± 21%; [mean ±SD] P% 0.0001). Conclusions The reduction of the CSvl vs. 100% indicates a direct reduction of cerebral blood flow velocity caused by isoflurane/sevoflurane, independently of systemic blood flow velocity.