SummaryAnimal studies have shown that injection pressures > 75 kPa indicate probable intrafascicular needle tip position. This study describes the flow/pressure characteristics of seven common needle systems. A syringe pump delivered flow rates of 5, 6.67, 10, 13.3, 15 and 20 ml.min À1 through these needle systems, while keeping the needle tips open to atmosphere. A pressure transducer connected between the syringe and needle provided a real-time graphical display for analysis. Mean plateau pressures increased linearly with flow and with decreasing needle diameter (2.7-92 kPa). Flow rates > 17 ml.min À1 and needle sizes 22 G and smaller produced mean plateau pressures > 75 kPa.Pressure monitors upstream from the needle may produce false-positive alarms at high flow rates due to needle resistance, and unreliable readings due to non-laminar flow. We recommend injection rates ≤ 15 ml.min À1 (0.25 ml.s À1 )to reduce the effect of factors upstream from the needle tip as a cause of high pressure readings.
Anabolic androgenic steroids are commonly used at high doses by bodybuilders and athletes to enhance physique and improve performance levels. We report a case of spontaneous hepatic rupture with life-threatening haemorrhage associated with a past history of anabolic steroid use.A nabolic androgenic steroids (AAS) are commonly used in high doses by bodybuilders and athletes to enhance physique and improve performance levels. These agents are known to produce changes in various organ systems and cause adverse effects such as gynaecomastia, hypertension, ischaemic heart disease, psychological disturbances, testicular atrophy and acne.1 They have also been associated with prostate cancer and nephroblastoma.2-4 AAS also have a profound impact on the liver, including peliosis hepatis, cholestasis and hepatocellular adenomas. 5 We report a case of spontaneous hepatic rupture with life-threatening haemorrhage associated with a history of anabolic steroid use. CASE REPORTA 43-year-old man was brought to the accident and emergency department after he collapsed at home. He had the physique of a professional bodybuilder. He reported that he had epigastric pain for 2 days before the collapse. There was no history of trauma. On examination, he was found to be markedly tender over the epigastric and left hypochondrial areas. On arrival, he had a heart rate of 124 beats/min and a blood pressure of 69/ 30 mm Hg. He was conscious and alert with an oxygen saturation of 100%. Investigations revealed a haemoglobin of 10.6 g/dl, an international normalised ratio of 4.2, creatinine of 148 mmol/l and bilirubin of 27 mmol/l. All other parameters were within normal limits. The patient was resuscitated in the accident and emergency department with intravenous fluids and was transferred to the high dependency unit. His medical history included Crohn's disease and a recurrent deep vein thrombosis related to a familial thrombophilia for which he took warfarin and anabolic steroids. He had stopped taking steroids 4 years previously. He had been taking AAS for 25 years, which included nandrolone decanoate, stanozolol, primabolin and most forms of testosterone. By comparison with the doses taken in the bodybuilding fraternity, his consumption was at the low end of the range of steroid usage. Before a computed axial tomography scan was performed, he had a cardiovascular collapse that required aggressive resuscitation with blood products and intravenous fluids, and he underwent an emergency laparotomy. Three litres of blood was evacuated from his abdomen. A ruptured subcapsular haematoma of the liver was identified as the source of the haemorrhage. The abdomen was packed as the haemorrhage was difficult to control, being aggravated by the raised international normalised ratio. His postoperative period was complicated by sepsis, and acute renal and cardiovascular failure requiring renal and inotropic support. Re-exploration of his abdomen at 72 h was uneventful. He subsequently made an uncomplicated but slow recovery, being extubated at 10 days an...
Minimum alveolar concentration (MAC) has been traditionally used to measure the potency of an inhalational anesthetic agent. Recently, bispectral index (BIS) derived from the frontal cortical electroencephalogram has been used frequently for quantifying the hypnotic component of anesthesia. The present study was designed to examine the BIS values produced by equi-MAC concentrations of halothane and isoflurane. In 34 patients undergoing spinal surgery, BIS and spectral edge frequency (SEF95) were recorded at 3 different concentrations of halothane and isoflurane--namely 0.5, 0.75, and 1.0 MAC. The measurements were made both during wash-in and wash-out phases of the anesthetic agent. Eighteen patients received halothane and 16 received isoflurane. Heart rate, mean arterial pressure, oxygen saturation, and end tidal carbon dioxide pressure values were not different between the 2 groups at various MAC concentrations of the anesthetic agents. BIS and SEF95 values decreased significantly with increasing concentrations of both the anesthetic agents (P<0.001). At any given MAC concentration of the anesthetic, BIS and SEF(95) values were significantly lower under isoflurane compared with halothane anesthesia both during wash-in and wash-out phases (P<0.001). For a given anesthetic agent, BIS values were comparable at equi-MAC concentrations during wash-in and wash-out phases. In conclusion, BIS values are significantly lower under isoflurane compared with halothane anesthesia at similar MAC concentrations. For a given anesthetic agent and a given MAC concentration, the BIS values are similar during wash-in and wash-out phases of anesthesia.
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