Anaesthesia
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Review
The application of three-dimensional printing technology in anaesthesia: a systematic review.
Three-dimensional printing has rapidly become an easily accessible, innovative and versatile technology, with a vast range of applications across a wide range of industries. There has been a recent emergence in the scientific literature relating to its potential application across a multitude of fields within medicine and surgery; however, its use within anaesthesia has yet to be formally explored. ⋯ We identified eight relevant articles. Due to the paucity of studies, we also completed a narrative review of the applications of three-dimensional printing pertinent to anaesthetic practice that our department are currently exploring, and suggest potential future uses for this technology relevant to our speciality.
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Observational Study
Effects of acute controlled changes in end-tidal carbon dioxide on the diameter of the optic nerve sheath: a transorbital ultrasonographic study in healthy volunteers.
Transorbital ultrasonographic measurement of the diameter of the optic nerve sheath is a non-invasive, bed-side examination for detecting raised intracranial pressure. However, the ability of the optic nerve sheath diameter to predict acute changes in intracranial pressures remains unknown. The aim of this study was to examine the dynamic changes of the optic nerve sheath diameter in response to mild fluctuations in cerebral blood volume induced by changes in end-tidal carbon dioxide. ⋯ With hypercapnia, there was a significant increase in optic nerve sheath diameter, with a mean (SD) increase from baseline 4.2 (0.7) mm to 4.8 (0.8) mm; p < 0.001. On return to normocapnia, the optic nerve sheath diameter rapidly reverted back to baseline values. This study confirms dynamic changes in the optic nerve sheath diameter with corresponding changes in carbon dioxide, and their reversibly with normocapnia.
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Observational Study
Heart rate variability as a predictor of hypotension following spinal for elective caesarean section: a prospective observational study.
Post-spinal hypotension remains a common and clinically-important problem during caesarean section, and accurate pre-operative prediction of this complication might enhance clinical management. We conducted a prospective, single-centre, observational study of heart rate variability in 102 patients undergoing elective caesarean section in a South African regional hospital. We performed Holter recording for ≥ 5 min in the hour preceding spinal anaesthesia. ⋯ Baseline heart rate (p = 0.20; OR 1.022, 95%CI 0.988-1.057) and BMI (p = 0.60; OR 1.017, 95%CI 0.954-1.085) did not predict hypotension. Heart rate variability analysis is a potentially useful clinical tool for the prediction of hypotension. Future studies should consider a low-frequency/high-frequency ratio threshold of 2.0 for prospective validation.
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Following the return of spontaneous circulation after out-of-hospital cardiac arrest, neurological dysfunction, airway or ventilatory compromise can impede transport to early percutaneous coronary intervention, necessitating pre-hospital or emergency department anaesthesia to facilitate this procedure. There are no published reports of the ideal induction agents in these patients. We sought to describe haemodynamic changes associated with induction of anaesthesia using a midazolam (0.1 mg.kg-1 ), fentanyl (2 μg.kg-1 ) and rocuronium (1 mg.kg-1 ) regimen developed using expert opinion, and adherence to the protocol by our pre-hospital teams. ⋯ Adherence to recommended fentanyl and rocuronium doses was high. Overall, systolic blood pressure was reduced following induction of anaesthesia, and systolic pressures < 90 mmHg occurred more often at measurements made later (up to 9 min) after induction. Changes in heart rate, and new hypertension were uncommon.