Addition of low-dose morphine to intrathecal bupivacaine/sufentanil labour analgesia: A randomised controlled study.

BACKGROUND: Single-shot spinal analgesia with bupivacaine and a short-acting opioid for labour pain is popular due to its simplicity, rapid onset, and profound analgesia without significant motor block. Its limitation is the short duration of action. Supplementation with intrathecal morphine has been shown to prolong analgesia. We compared the addition of placebo or morphine 50 or 100 µg to intrathecal bupivacaine and sufentanil to evaluate the impact on duration of labour analgesia. METHOD: Following ethics committee approval and verbal and written patient consent, 90 healthy nulliparous women were included in the study. As part of a combined spinal-epidural technique, women were randomised to receive intrathecal bupivacaine 1.25mg and sufentanil 5 µg with morphine 50 µg, 100 µg or saline placebo in a double-blind fashion. Onset of analgesia was measured as the time from intrathecal injection to a visual analogue scale pain score < or =4 (scale 0-10) and the duration of analgesia as the time from intrathecal injection to the return of pain >4. RESULTS: No significant differences between the groups were seen in onset or duration of analgesia, side effects or obstetric and neonatal outcome. CONCLUSION: The addition of 50 or 100 µg morphine to 1.25mg bupivacaine and 5 µg sufentanil during established labour did not significantly increase the duration of analgesia.

Prolonged exposure to inhaled nitric oxide transiently modifies tubular function in healthy piglets and promotes tubular apoptosis.

AIM: Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator. We hypothesized that those piglets exposed to prolonged iNO react with a modified renal function. METHODS: Randomized, placebo-controlled exposure to 40 p.p.m. iNO (30 h) in piglets (n = 20). Plasma and urine were sampled during three periods (first and second 12 h periods, and finally a 6 h period). We measured urine volumes, plasma and urine electrolytes (UNa, UK, UCl), plasma creatinine and urea. We calculated creatinine clearance (Ccr), and fractional excretions of sodium and potassium (FENa, FEK) and urinary excretions of electrolytes (UENa, UEK, UECl). Haemodynamic data were recorded and renal tubular apoptosis detected. RESULTS: For the first 12 h, certain parameters significantly increased in the iNO group (mean +/- SD): UNa (mmol L(-1)), 87.7 (+/-35.0) vs. 39.3 (+/-22.9), UCl (mmol L(-1)) 80.4 (+/-32.8) vs. 48.0 (+/-26.7), FENa (%) 2.1 (+/-0.8) vs. 0.7 (+/-0.5), FEK (%) 31.7 (+/-7.0) vs. 20.7 (+/-12.3), as well as UENa (mmol) 61.0 (+/-21.1) vs. 27.6 (+/-17.9) and UECl (mmol) 57.3 (24.5) vs. 37.6 (29.0). These changes were absent in the second and third periods of the study. Significant differences in percentage of apoptotic cell nuclei in the renal cortex and medulla were found after iNO exposure: 39% vs. 15%. CONCLUSION: Exposure to 40 p.p.m. iNO in healthy anaesthetized piglets has a transient natriuretic effect that disappears after 12 h. We also found evidence of renal tubular apoptosis promotion after 30 h of iNO.

Effects of exaggerated lithotomy position on ventilation and hemodynamics during radical perineal prostatectomy.

Ventilation and haemodynamics were studied in nine anaesthetized male patients undergoing perineal prostatectomy in the exaggerated lithotomy position (flexed, head-down position). In the flexed head-down position, as compared to the supine position, there was a significant decrease in arterial oxygen tension (13.1 +/- 2.1 to 11.2 +/- 1.1 kPa, p < 0.001), a significant increase in carbon dioxide tension (4.6 +/- 5.7 to 5.7 +/- 0.2 kPa, p < 0.001) and shunt fraction (7.8 +/- 2.3 to 14.0 +/- 3.0%, p < 0.01). There were also increases in pulmonary wedge pressures (11.3 +/- 2.9 to 17.9 +/- 2.9 mmHg, p < 0.01), mean pulmonary artery pressures (17.6 +/- 3.8 to 25.2 +/- 3.5 mmHg, p < 0.001) and central venous pressures (11.9 +/- 2.1 to 14.7 +/- 2.8, p < 0.05). Mean arterial pressure fell from 92 +/- 14 to 75 +/- 10 mmHg (p < 0.05). Heart rate and cardiac output were unchanged. All these changes had already been seen but to a lesser extent when the patients were positioned in the flexed supine position. When the patients were returned to the supine position following surgery, arterial oxygen tension was returned to baseline values. Mean pulmonary artery, pulmonary capillary wedge and central venous pressures also fell significantly. It is concluded that the extreme exaggerated lithotomy used during surgery results in impaired oxygenation and increased cardiac filling pressures but to acceptable levels in healthy anaesthetized patients. All values returned to normal when patient position was normalized after surgery.

Extracorporeal carbon dioxide removal performed with surface-heparinized equipment in patients with ARDS.

To avoid the drawbacks of systemic anticoagulation during prolonged extracorporeal circulation in patients with adult respiratory distress syndrome (ARDS) a heparinization technique has been developed by which partially degraded heparin can be covalently end-point attached to the surface of the equipment constituting the extracorporeal circuit (Carmeda Bio-Active Surface, CBAS) thereby localizing the anticoagulatory effect. Since 1986 we have used extracorporeal circuits and membrane lungs coated with the CBAS for extracorporeal lung assistance (ECLA) in 14 patients suffering from ARDS. The patients were on ECLA for 3 to 55 days with a survival rate of 43%. Our experience so far is that by using equipment coated with CBAS it is possible to perform long-term extracorporeal circulation with a minimum of intravenously administered heparin, thus avoiding the risk of major coagulation defects.