Anaesthesia
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Many anaesthetic agents affect intra-ocular pressure, yet little is known about nitrous oxide and intra-ocular pressure. This study assessed the effect of nitrous oxide on intra-ocular pressure in 20 healthy adult volunteers. The intra-ocular pressure was measured at baseline, while breathing a 70:30 mix of nitrous oxide and oxygen for 12 min, and then while breathing room air for 15 min. ⋯ There was no significant difference in intra-ocular pressure between baseline and during or after nitrous oxide inhalation. Several differences in intra-ocular pressure were noted between internal time-points: pressure increased by 2.4 mmHg between 3 and 6 min of breathing nitrous oxide (p=0.01); it increased by 1.4 mmHg between 3 and 9 min of breathing nitrous oxide (p=0.046); and it decreased by 2.2 mmHg between 6 min of breathing nitrous oxide and 15 min of breathing room air (p=0.035). This study indicates that nitrous oxide inhalation does not significantly change intra-ocular pressure from baseline values in a population of healthy adults.
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The aim of the present study was to determine the precision of the PiCCO(®) system for post-cardiac arrest patients who underwent therapeutic hypothermia. The precision of the measurements for cardiac output, global end-diastolic volume, extravascular lung water and the pulmonary vascular permeability index was assessed using the least significant change; this was regarded as precise when less than 15%. ⋯ No significant differences between hypothermia (n=150) and non-hypothermia (n=312) were found. The PiCCO-derived variables were found to be precise for post-cardiac arrest patients even under conditions of varying body temperature.
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We compared the ability of automated non-invasive intermittent oscillometric blood pressure monitoring with a new device, CNAP(TM) (continuous non-invasive arterial pressure) to provide a new blood pressure reading in each 1-min interval between spinal anaesthesia and delivery during caesarean section. We also compared the accuracy of continuous non-invasive arterial pressure readings with non-invasive blood pressure measurements before spinal anaesthesia. Fifty-nine women participated. ⋯ Continuous non-invasive arterial pressure was more likely to fail on two or more consecutive minutes (p=0.001). From the pre-spinal readings, the mean bias, defined as non-invasive-continuous non-invasive arterial pressure, and limits of agreement (±2SD mean bias) for systolic, diastolic and mean blood pressure respectively were +1.3 (±26.0), -2.9 (±21.8) and +2.6 (±20.4) mmHg. The new monitor has disadvantages compared with conventional non-invasive intermittent blood pressure monitoring.
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There are conflicting results with regard to the use of catheter-based techniques for continuous paravertebral block. Local anaesthetic spread within the paravertebral space is limited and the clinical effect is often variable. Discrepancies between needle tip position and final catheter position can also be problematic. ⋯ The median (IQR [range]) caudo-cephalad spread of contrast dye injectate through a subset of 20 catheters was 4 (4-5[3-8]) thoracic segments. All catheters were removed without incident. Precise paravertebral catheter placement can be achieved using ultrasound-guided placement of a coiled catheter.
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Forced-air warming exhaust may disrupt operating theatre airflows via formation of convection currents, which depends upon differences in exhaust and operating room air temperatures. We investigated whether the floor-to-ceiling temperatures around a draped manikin in a laminar-flow theatre differed when using three types of warming devices: a forced-air warming blanket (Bair Hugger™); an over-body conductive blanket (Hot Dog™); and an under-body resistive mattress (Inditherm™). ⋯ We conclude that forced-air warming generates convection current activity in the vicinity of the surgical site. The clinical concern is that these currents may disrupt ventilation airflows intended to clear airborne contaminants from the surgical site.