Anaesthesia
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Randomized Controlled Trial
Evaluation of radial and ulnar blood flow after radial artery cannulation with 20- and 22-gauge cannulae using duplex Doppler ultrasound.
This study evaluated ulnar and radial artery blood flow after radial artery cannulation during general anaesthesia using Doppler ultrasound. A total of 80 patients were randomly assigned to receive radial artery cannulation with either a 20-G or 22-G cannula. Arterial diameter, peak systolic velocity, end-diastolic velocity, resistance index and mean volume flow were measured at four time points in both arteries: before anaesthesia; 5 min after intubation; immediately after cannulation; and 5 min after cannulation. ⋯ Radial blood flow was decreased immediately after cannulation and recovered to pre-cannulation values 5 min after cannulation. There were no statistical differences between groups at each time point. Radial artery cannulation causes compensatory increase in ulnar artery blood flow, and the difference in cannula size has minimal effect on this change.
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This study aimed to compare the haemodynamics in healthy pregnant women with the haemodynamics in women with untreated pre-eclampsia, to determine the cardiovascular reason for hypertension in pre-eclampsia. 40 women with untreated pre-eclampsia, 40 matched healthy pregnant women and 20 non-pregnant women were studied using transthoracic echocardiography. Untreated pre-eclampsia demonstrated (mean (SD), healthy non-pregnant vs healthy pregnant vs untreated pre-eclampsia) increased cardiac output (3400 (752) vs 4109 (595) vs 4789 (1416) ml.min(-1), p=0.002), increased stroke volume (53 (10) vs 53 (8) vs 59 (13) ml, p=0.04), increased fractional shortening (35 (5) vs 35 (7) vs 41 (8) %, p=0.006), increased fractional area change (57 (7) vs 57 (9) vs 65 (9)%, p=0.002) and increased systemic vascular resistance (2116 (457) vs 1613 (315) vs 2016 (625) dyne.s.cm(-5), p=0.001). Mitral E/septal e' was higher (6.0 (1.1) vs 6.7 (1.3) vs 10.4 (2.4), p=0.002) and left atrial size increased (3.2 (0.3) vs 3.8 (0.4) vs 4.0 (0.4) cm, p=0.002). Hypertension in untreated pre-eclampsia is due to increased cardiac output and mild vasoconstriction, with increased inotropy and reduced diastolic function.
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Clinical Trial
Platelet mapping as part of modified thromboelastography (TEG®) in patients undergoing cardiac surgery and cardiopulmonary bypass.
The platelet-mapping assay of the thromboelastograph was used to measure platelet aggregation and to examine the effect of cardiopulmonary bypass on multiple platelet receptors and the role of altered receptor activity in postoperative bleeding. The percentage platelet aggregation for collagen, adenosine diphosphate and arachidonic acid was measured in 40 patients divided post-hoc into high- or low-bleeding groups depending on postoperative 24-h chest tube output. ⋯ This finding was significantly correlated with the 24-h chest tube drainage, and it predicted postoperative bleeding with a sensitivity of 83% and a specificity of 68%. Therefore, platelet aggregation is reduced following cardiopulmonary bypass, and this may play a role in predicting postoperative blood loss.
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Haemorrhage remains an important cause of maternal mortality worldwide. Cell salvage carries a theoretical risk of amniotic fluid embolus syndrome and is too expensive for use in many parts of the world. To explore cheaper options, we investigated whether a leucocyte depletion filter alone removes components of pure amniotic fluid. ⋯ Lamellar bodies and fetal squames were almost completely removed (filtration efficacy 96.6% and 99.9%, respectively; p<0.0001 and <0.0004), and hair was completely removed (p=0.002). Filtration had no effect on concentrations of α-fetoprotein, tissue factor or endothelin-1, or on the presence of meconium or vernix. Additional work is required to evaluate whether cell salvage using filtration alone may be useful in maternal haemorrhage in the developing world.
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Case Reports
Catastrophic complication of an interscalene catheter for continuous peripheral nerve block analgesia.
We report a catastrophic postoperative complication of a prolonged interscalene block performed under general anaesthesia. The course of the anaesthetic was uneventful and the patient remained stable during his stay in the recovery area with the operative extremity paralysed and insensate. ⋯ The patient was next assessed 6.5 h later when he was found dead in his bed. A postmortem CT scan revealed the catheter to be sited intrathecally, presumably the result of dural sleeve penetration.