British Journal of Anaesthesia - current issue

British Journal of Anaesthesia - RSS feed of current issue
  1. Opioid Risk Management
  2. The Complete Recovery Room Book
  3. Comprehensive Atlas of Ultrasound-Guided Pain Management Injection Techniques
  4. Pain in Women
  5. The Anaesthetic Crisis Manual
  6. {beta}-Blockers and cardiac protection
  7. Trachway in assistance of nasotracheal intubation with a preformed nasotracheal tube in patients undergoing oral maxillofacial surgery
  8. Finding the bulging edge: a modified shamrock lumbar plexus block in average-weight patients
  9. In-plane ultrasound-guided needle insertion ALONG or ACROSS the visual axis hand positions
  10. Component reductions in oxygen delivery generate variable haemodynamic and stress hormone responses
    Background

    In clinical practice, global oxygen delivery (DO2) is often considered as a whole; however pathological and adaptive responses after a decrease in individual constituents of the DO2 equation (cardiac output, haemoglobin, oxyhaemoglobin saturation) are likely to be diverse. We hypothesized that an equivalent decrease in DO2 after reductions in each separate component of the equation would result in different haemodynamic, tissue oxygenation, and stress hormonal responses.

    Methods

    Anaesthetized, fluid-resuscitated male Wistar rats were subjected to circulatory, anaemic, or hypoxic hypoxia (by haemorrhage, isovolaemic haemodilution, and breathing a hypoxic gas mix, respectively), produced either rapidly over 5 min or graded over 30 min, to a targeted 50% decrease in global oxygen delivery. Sham-operated animals acted as controls. Measurements were made of haemodynamics, skeletal muscle tissue oxygen tension, blood gas analysis, and circulating stress hormone levels.

    Results

    Whereas haemorrhage generated the largest decrease in cardiac output, and the greatest stress hormone response, haemodilution had the most marked effect on arterial pressure. In contrast, rapid hypoxaemia produced a minor impact on global haemodynamics yet induced the greatest decrease in regional oxygenation. A greater degree of hyperlactataemia was observed with graded insults compared with those administered rapidly.

    Conclusions

    Decreasing global oxygen delivery, achieved by targeted reductions in its separate components, induces varying circulatory, tissue oxygen tension, and stress hormone responses. We conclude that not all oxygen delivery is the same; this disparity should be emphasized in classical teaching and re-evaluated in patient management.

  11. Isoflurane induces endoplasmic reticulum stress and caspase activation through ryanodine receptors
    Background

    Isoflurane has been reported to induce caspase-3 activation, which may induce neurotoxicity and contribute to the pathogenesis of Alzheimer's disease. However, the underlying mechanism is largely unknown, especially whether or not isoflurane can induce ryanodine receptors (RyRs)-associated endoplasmic reticulum (ER) stress, leading to caspase-3 activation. We therefore assessed the effects of isoflurane on RyRs-associated ER stress.

    Methods

    We treated primary neurones from wild-type (C57BL/6J) mice with 1% and 2% isoflurane for 1, 3, or 6 h. We then measured levels of C/EBP homologous protein (CHOP) and caspase-12, two ER stress markers, using immunocytochemistry staining and western blotting analysis. Dantrolene (5 μM), the antagonist of RyRs, was used to investigate the role of RyRs in the isoflurane-induced ER stress and caspase-3 activation.

    Results

    Isoflurane 2% for 6 h treatment increased the levels of CHOP (876% vs 100%, P=0.00009) and caspase-12 (276% vs 100%, P=0.006), and induced caspase-3 activation in the neurones. The administration of 2% isoflurane for 3 h (shorter duration), however, only increased the levels of CHOP (309% vs 100%, P=0.003) and caspase-12 (266% vs 100%, P=0.001), without causing caspase-3 activation. The isoflurane-induced ER stress (CHOP: F=16.64, P=0.0022; caspase-12: F=6.13, P=0.0383) and caspase-3 activation (F=32.06, P=0.0005) were attenuated by the dantrolene treatment.

    Conclusions

    These data imply that isoflurane might induce caspase-3 activation by causing ER stress through RyRs, and dantrolene could attenuate the isoflurane-induced ER stress and caspase-3 activation. Further investigations of the potential neurotoxicity of isoflurane are needed.

  12. Reduction of cerebral mean blood flow velocity and oxygenation after high-volume (1.5 ml kg-1) caudal block in infants
    Background

    We have recently described a bi-directional bulk flow of cerebrospinal fluid (CSF) (coined ‘the CSF rebound mechanism’) after the use of high-volume caudal block in infants, which may explain the secondary longitudinal spread of the block. If important the initial cephalad transfer of CSF should be of such a magnitude that it would cause a transient reduction in cerebral blood flow (CBF) and cerebral oxygenation. The primary aim of this observational study was to delineate the magnitude of the reduction of CBF velocity (CBFV) associated with high-volume caudal block in infants.

    Methods

    Ultrasound Doppler measurements of CBFV in the middle cerebral artery and also haemodynamic parameters and cerebral regional oxygenation (CRSO2) were followed during 5 min after the initial caudal injection (1.5 ml kg–1, ropivacaine 0.2%) in 12 infants <3 months of age.

    Results

    The caudal injection was associated with immediate and major reductions in CBFV indicating a concomitant reduction in CBF. A significant reduction of cerebral regional oxygenation CRSO2 was also observed. Systemic haemodynamic parameters were unchanged during the observation period.

    Conclusion

    High-volume caudal block causes a biphasic change in CBFV and was also found to affect cerebral oxygenation. Our findings lend further support to ‘the CSF rebound mechanism’ for secondary spread of high-volume caudal block.

  13. Influence of intensive care treatment on the protein binding of sufentanil and hydromorphone during pain therapy in postoperative cardiac surgery patients
    Background

    Our objective was to evaluate the effect of intensive care treatment on the protein binding of sufentanil and hydromorphone in cardiac surgery patients during postoperative analgesia using a target-controlled infusion (TCI) and patient-controlled analgesia (PCA).

    Methods

    Fifty adult patients were enrolled in this prospective randomized study; of which, 49 completed the study (age range 40–81 yr). Sufentanil was administered as an analgesic intraoperatively, and hydromorphone was dosed after operation with TCI and PCA until 8 a.m. on the first postoperative day. Arterial plasma samples were collected for drug and protein concentration measurements up to 24 h after cardiac surgery. Corresponding patient data were collected from the electronic patient data system. After explorative data analysis with principal component analysis, multivariate regression analysis and non-linear mixed effects modelling was used to study the effect of treatment on protein binding.

    Results

    Data of 35 patients were analysed. The median protein binding of sufentanil and hydromorphone was 88.4% (IQ range 85.7–90.5%) and 11.6% (IQ range 9.5–14.3%), respectively. Free fraction of sufentanil increased towards the end of the study period, whereas hydromorphone free fraction remained nearly constant. The total sufentanil concentration and volume balance were identified as significant covariates for the protein binding of sufentanil. For the protein binding of hydromorphone, no significant covariate effects were found.

    Conclusions

    Sufentanil protein binding was significantly dependent on changes in the total drug concentration and volume balance addressing the importance of adequate dosing and fluid-guided therapy. Hydromorphone protein binding was nearly constant throughout the study period.

    Clinical trial registration

    EudraCT 2011-003648-31 and ClinicalTrials.gov: NCT01490268.

  14. Accuracy and precision of the ultrasound cardiac output monitor (USCOM 1A) in pregnancy: comparison with three-dimensional transthoracic echocardiography
    Background

    Cardiac output (CO) monitoring is helpful in the assessment of critically ill pregnant women, but invasive monitors are often unsuitable for use. We aimed to measure agreement between the non-invasive ultrasound cardiac output monitor (USCOM) and three-dimensional transthoracic echocardiography (3D-TTE) in pregnant women.

    Methods

    Healthy pregnant women from 25 weeks gestation onwards participated. In the left lateral position at rest, CO was measured with the USCOM and 3D-TTE. A single operator performed all USCOM measurements, with a different operator performing all echocardiography. Both were blinded to results from the other device. Each USCOM trace was analysed using two modes: flowtrace (FT) and touchpoint (TP). A second, blinded USCOM reading was taken to assess reproducibility.

    Results

    USCOM readings were obtained in 92, and 3D-TTE images in 85 participants. The mean CO was 5.7, 7.7, and 6.2 litre min–1 measured by 3D-TTE, USCOM FT, and USCOM TP, respectively. USCOM bias was +2.0 litre min–1 (FT) and +0.4 litre min–1 (TP). Limits of agreement were –0.2 to +4.2 litre min–1 (FT) and –1.4 to +2.3 litre min–1 (TP). The mean percentage difference was 32.6% (FT) and 31.4% (TP) for CO and 27.0% (FT) and 27.5% (TP) for stroke volume. Intraclass correlation between repeated USCOM readings was 0.9 (FT) and 0.86 (TP).

    Conclusions

    USCOM has acceptable agreement with 3D-TTE for the measurement of CO in pregnancy. The positive bias of the USCOM, particularly in the FT mode, may be due to the hyperdynamic cardiovascular state in pregnancy. We suggest using the TP mode in this patient population.

  15. Risk factors for obstetric morbidity in patients with uterine atony undergoing Caesarean delivery
    Background

    Uterine atony (UA) is recognized as a leading cause of postpartum haemorrhage. However, knowledge of risk factors of haemorrhage-related morbidity among patients diagnosed with UA is uncertain. We investigated risk factors for haemorrhage-related morbidity among patients undergoing Caesarean delivery with UA.

    Methods

    We conducted a secondary analysis of data sourced from a 4-yr observational study at 19 US academic centres. Patients with UA were identified based on receiving methylergonovine or carboprost. Our primary outcome (haemorrhage-related morbidity) included a composite of intra- or postpartum transfusion; Caesarean hysterectomy; uterine or hypogastric artery ligation; intensive care admission for: pulmonary oedema, coagulopathy, adult respiratory distress syndrome, postoperative ventilation, or invasive line monitoring.

    Results

    Among 57 182 patients who underwent Caesarean delivery, 2294 (4%) patients developed UA. Haemorrhage-related morbidity occurred in 450 (19.6%) patients with UA. The risk of haemorrhage-related morbidity was increased among African-Americans [adjusted odds ratio (aOR)=2.36; 95% confidence interval (CI)=1.73–3.23], Hispanics (aOR=1.4; 95% CI=1.04–1.9), women with multiple gestations (aOR=1.59; 95% CI=1.06–2.38), placenta praevia (aOR=4.89; 95% CI=3.04–7.87), patients with ASA class III (aOR=1.4; 95 CI=1.03–1.9), or ASA class IV (aOR=5.88; 95% CI=2.48–13.9), exposure to general anaesthesia (GA) (aOR=2.4; 95% CI=1.59–3.62) and combined general and regional anaesthesia (aOR=4.0; 95% CI=2.62–6.09), and ≥2 prior Caesarean deliveries (aOR=1.62; 95% CI=1.1–2.39).

    Conclusions

    Among patients with UA undergoing Caesarean delivery, the risk of haemorrhage-related morbidity is increased in African-Americans, Hispanics, patients with multiple gestations, placenta praevia, ASA class III or IV, ≥2 prior Caesarean deliveries and those undergoing GA.