British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the effects of ketamine-midazolam with those of fentanyl-midazolam on cortical somatosensory evoked potentials during major spine surgery.
Cortical somatosensory evoked potentials (CSEP) allow monitoring of spinal cord function during surgery. Ketamine has been shown to enhance CSEP amplitude, but there is no previous study comparing its effects with those of other anaesthetic regimens. Therefore, we have compared the effects of ketamine with those of fentanyl, both combined with midazolam, on CSEP monitoring during major spine surgery. ⋯ Nevertheless, we did not observe any significant differences in amplitudes or latencies between the two groups. The delay in obtaining the first voluntary postoperative motor response was significantly greater in the ketamine group (170 (54) vs 55 (17) min, P < 0.01). Both ketamine and fentanyl allowed us to obtain reliable CSEP during major spine surgery, and there were no significant difference between these two anaesthetic regimens for CSEP monitoring, but a longer delay for voluntary postoperative motor assessment was observed in the ketamine group.
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The use of inhaled nitric oxide in the critically ill has increased significantly over the past few years but little published information exists on standards for current practice. Sixty-four intensive therapy units in the UK were surveyed by questionnaire from which 54 (84.4%) satisfactory replies were received. We present the survey results and put forward recommendations based on current literature and our own clinical experience for the safe use of inhaled nitric oxide.
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Randomized Controlled Trial Comparative Study Clinical Trial
Hyaluronidase and peribulbar block.
We have assessed the effect of two concentrations of hyaluronidase on the quality of peribulbar block, using a low volume, single injection technique. We studied 200 patients undergoing elective intraocular surgery, allocated randomly to one of three groups. Group 1 (n = 50) received peribulbar block with 5 ml of a 1:1 mixture of 0.5% plain bupivacaine and 2% plain lignocaine. ⋯ The incidence of satisfactory block at 5 min was increased in both groups given hyaluronidase (group 2, P < 0.05; group 3, P < 0.001). There were no significant differences between groups 2 and 3 with respect to quality of block at 5 min. Hyaluronidase in both concentrations improved the quality of peribulbar block at 5 min, and when used in a concentration of 300 iu ml-1, also improved the speed of onset of block.
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The processed electroencephalogram (pEEG) was monitored in eight patients undergoing gynaecological laparotomy under combined extradural and nitrous oxide-isoflurane anaesthesia. Pre-incisional mean spectral edge frequency 95 percentile (SEF95) and median frequency (MF) were 11.67 (SD 1.63) Hz and 3.74 (0.24) Hz, respectively. ⋯ After introduction of extradural analgesia, these variables returned to pre-incisional values (SEF95 11.65 (1.73); MF 4.02 (0.41)). Reduction of end-tidal isoflurane from 1.0% to 0.5% after extradural analgesia did not cause significant pEEG changes. pEEG may assist anaesthetists to recognize adequacy of combined general-extradural anaesthesia.
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Eight patients were studied under general anaesthesia for elective pulmonary lobectomy to see if intrinsic positive end-expired pressure (PEEPi) would appear or increase in the dependent lung during one-lung ventilation (OLV) or if application of external PEEP equal to individually measured PEEPi would produce better arterial oxygenation, haemodynamic state and oxygen delivery than either zero PEEP (ZEEP) or an external PEEP 5 cm H2O greater than PEEPi. Patients were non-obese, without obstructive airways disease, aged 53-76 yr and ASA < III. ⋯ There was no PEEPi during TLV, but 2-6 mm Hg of PEEPi appeared during OLV. Applying external PEEP equal to individually measured PEEPi reduced venous admixture and increased PaO2 without a decrease in cardiac index (thus increasing oxygen delivery) compared with ZEEP, but the improvement in pulmonary gas exchange was lost and an additional penalty of reduced cardiac output was imposed when external PEEP was increased to 5 mm Hg above PEEPi.