Anaesthesia
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Standard cardiorespiratory monitoring may fail to detect occult tissue ischaemia. This study assessed whether a near infra-red spectroscopy tissue oxygen saturation monitor (InSpectra™) could detect progressive peripheral tissue ischaemia and whether hyperoxia may confound tissue oxygen saturation measurement. ⋯ The rate and magnitude of decreases in tissue oxygen saturations were greater during high- than low-pressure ischaemia with a mean (SD) desaturation rate of 3.3 (0.9) vs 1.8 (0.8) %.min(-1) (p<0.01). The dose-related association and lack of confounding by hyperoxia suggest that tissue oxygen saturation monitoring may be a useful adjunct to detect occult ischaemia.
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Review Meta Analysis Comparative Study
A meta-analysis of the accuracy and precision of the ultrasonic cardiac output monitor (USCOM).
The ultrasonic cardiac output monitor is a non-invasive, continuous-wave Doppler monitor that can be used to measure cardiac output. Its accuracy and precision in peri-operative and critical care has been assessed with varied results. ⋯ The mean weighted bias was -0.39 l.min(-1) (95% CI -0.25 to -0.53 l.min(-1) ), precision 1.27 l.min(-1) and percentage error 42.7% (95% CI 38.5-46.9%). The ultrasonic cardiac output monitor achieved similar agreement with bolus thermodilution to that of other minimally invasive methods of peri-operative cardiac output monitoring, and may have a useful role in cardiac output monitoring.
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Clinical Trial
The effect of a cervical collar on the seal pressure of the LMA Supreme™: a prospective, crossover trial.
For personnel inexperienced in airway management, supraglottic airway devices may be the first choice in an emergency. Changing head position is known to reduce the seal pressure of a laryngeal mask airway. The aim of this study was to investigate whether the use of a cervical collar improves the stability of airways secured with the LMA Supreme™ (The Laryngeal Mask Company Limited, Mahé, Seychelles). ⋯ With a cervical collar in place, the seal pressure increased to 28 (22.8-30 [17-30]) cmH(2) O (p<0.001). In the neutral head position, the seal pressure was 22 (17.6-24.5 [12-30]) cmH(2) O without and 27 (22-30 [12-30]) cmH(2) O with a cervical collar in place (p<0.001). We found that a cervical collar stabilises the airway with an LMA Supreme in place and we recommend this combination for (pre-hospital) emergency cases.
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We conducted a study to assess pharmacokinetics of high-dose tranexamic acid for 24 h after administration of the drug in patients undergoing cardiac surgery with cardiopulmonary bypass. High-dose tranexamic acid involved a bolus of 30 mg.kg(-1) infused over 15 min followed by a 16 mg.kg(-1) .h(-1) infusion until chest closure with a 2 mg.kg(-1) load within the pump prime. ⋯ Mean plasma tranexamic acid concentrations during the intra-operative period and in the first 6 postoperative hours were consistently higher than the suggested threshold to achieve 100% inhibition and 80% inhibition of tissue plasminogen activator. With recent studies implicating high-dose tranexamic acid as a possible aetiology of postoperative seizures following cardiac surgery, the minimum effective yet safe dose of tranexamic acid in high-risk cardiac surgery needs to be refined.