Anaesthesia
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We have investigated the factors predicting umbilical arterial pH (UA pH) and standard base excess (UA BE) in 337 consecutive elective Caesarean sections performed under spinal anaesthesia. Multiple linear regression analysis was performed with UA pH and UA BE as the dependent factors. ⋯ The significant factors predicting UA BE were: use of ephedrine and the interaction between ephedrine use and duration of hypotension (adjusted R2 = 0.52, F15,321 = 25.0, p < 0.0001). We conclude that, in order to minimise the risk of fetal acidosis, ephedrine should not be used before delivery, uterine incision-to-delivery time should be as short as possible, and alpha-agonists such as metaraminol or phenylephrine should be used to minimise both the magnitude and duration of hypotension.
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Over a period of one year, a weekly telephone survey identified 161 stable patients with weaning delay (defined as patients ventilated for at least 6 h per day for more than 2 weeks) in intensive care units in the Northern Region of England. Their median age was 69 years (range 21-88 years). Sixty patients (37%) were admitted with medical conditions, 89 (55%) were postoperative patients, whereas 12 (8%) were surgical but required non-operative admission. ⋯ Twenty patients (12%) required more than 28 days of respiratory support. These patients occupied on average 6.0% of available intensive care unit beds in the region. This study suggests that in the Northern Region of England there are a significant number of stable but ventilator-dependent patients occupying intensive care beds.
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Randomized Controlled Trial Comparative Study Clinical Trial
Mainstream vs. sidestream capnometry for prediction of arterial carbon dioxide tension during supine craniotomy.
We compared the performance of mainstream capnometry as a measure of arterial carbon dioxide tension (Paco2) with sidestream recordings in adult neurosurgical patients undergoing supine craniotomy. Two hundred and forty patients were randomly assigned so that the end-tidal carbon dioxide tension (PEco2) was measured using either a mainstream or sidestream infrared capnometer. All patients received propofol anaesthesia and ventilation was adjusted according to clinical requirement. ⋯ In both capnometers, the arterial to end-tidal difference in carbon dioxide tension did not change with time. However, there was greater within-patient variation in the sidestream group. Our study showed that mainstream PEco2 provided a more accurate estimation of Paco2 than sidestream measurement.