The analgesic effects of intrathecal morphine in comparison with ultrasound-guided transversus abdominis plane block after caesarean section: a randomised controlled trial at a Ugandan regional referral hospital.

Both transversus abdominis plane block and intrathecal morphine may produce prolonged postoperative analgesia, but the respective clinical outcomes of these anaesthetic techniques in resource-limited settings are not well described. We randomly assigned patients undergoing caesarean section to receive a hyperbaric bupivacaine (10 mg) spinal anaesthetic followed by an ultrasound-guided transversus abdominis plane block, or a hyperbaric bupivacaine (10 mg) spinal anaesthetic with 100 mcg intrathecal morphine, followed by a postoperative sham block. Supplemental postoperative analgesia included self-administered oral diclofenac 50 mg and paracetamol 1 g every 8 h. Numerical pain rating scores, the need for rescue medication, side-effects and patient satisfaction were recorded at 8, 16 and 24 h. We enrolled a total of 130 patients, with 65 women in each group. The mean numerical rating score for intrathecal morphine vs. transversus abdominis plane blocks at 8 h were: at rest, 2.5 vs. 3.1 (p = 0.04); with coughing, 4.3 vs. 4.8 (p = 0.07); and with movement, 3.6 vs. 4.2 (p = 0.06). At 16 h, respective scores were: 2.9 vs. 3.1 (p = 0.40) at rest; 4.0 vs. 4.3 (p = 0.19) with coughing; and 4.8 vs. 5.0 (p = 0.33) with movement. At 24 h, the respective scores were: 2.9 vs. 2.3 (p = 0.01); 4.6 vs. 4.2 (p = 0.04) with coughing; and 3.9 vs. 3.4 (p = 0.02) with movement. The need for rescue medication and the incidence of pruritis, sedation and nausea and vomiting were similar in both groups. Patient satisfaction with pain control was similar in both groups, with the majority of patients reporting satisfaction as good or excellent. Intrathecal morphine and transversus abdominis plane block provided clinically similar outcomes for pain relief after caesarean section.

Effect of pH and lidocaine on beta-adrenergic receptor binding. Interaction during resuscitation?

Epinephrine and other beta-adrenergic receptor (beta AR) agonists are often administered during cardiopulmonary resuscitation, a time when acid-base abnormalities and arrhythmias also commonly occur. We tested whether beta 2AR binding is influenced by pH or the antiarrhythmic drug lidocaine, and whether pH might influence the interaction of lidocaine with beta 2ARs. With institutional review board approval and informed consent, 32 venous blood samples were obtained from volunteers. Lymphocytes (which bear beta 2ARs similar to those found in heart) were isolated by density gradient centrifugation. Specific binding of the beta AR ligand 3H-dihydroalprenolol (3H-DHA) was determined with lidocaine concentrations ranging from 10(-6) to 10(-2) mol/L (n = 18 experiments), and with and without lidocaine (n = 10 experiments), 100 mumol/L, and with and without QX314 (a permanently charged lidocaine derivative), 1 mmol/L (n = 4 experiments). Data are presented as percent of control-specific binding measured at a pH of 7.4. Statistical analysis consisted of Spearman's rank-test. 3H-DHA-specific binding increased (p < .001) with pH. Thus, alkaline conditions favored binding of 3H-DHA to the receptor. Lidocaine inhibited 3H-DHA binding to beta 2ARs in a concentration-dependent manner. The concentration that inhibited specific binding of 3H-DHA by 50% was 3.1 x 10(-4) mol/L (95% confidence limits, 1.3 x 10(-4) to 7.5 x 10(-4) mol/L). Lidocaine potency at inhibiting beta 2AR binding also increased with increasing pH; thus, there was limited benefit (in terms of increasing binding to beta 2ARs) to increasing pH when lidocaine was present. QX314, despite being present in a 10-fold greater concentration than lidocaine, had no effect on 3H-DHA binding at any tested pH. The affinity of beta 2 ARs for both 3H-DHA and lidocaine increased with pH. Thus, the response to beta 2AR agonists (when no lidocaine is present) might be expected to be greater with normal or alkalotic pH than under acidotic conditions, supporting the correction of metabolic acidosis to achieve optimal effects from beta 2AR agonists during resuscitation.

Optical verification of a technique for in situ ultrasonic measurement of articular cartilage thickness.

Several investigators have used pulse-echo ultrasonics to measure the thickness of articular cartilage in situ. The underlying assumption in all measurements was that the second reflection used in thickness calculations was from the calcified-cartilage/cartilage boundary (tidemark). To investigate this assumption, the thickness of 24 cartilage plugs excised from a human femoral head was measured both ultrasonically and optically. Measurements established that the second reflection was from the tidemark and validated the ultrasonic technique as a method of mapping the thickness distribution of articular cartilage in synovial joints in situ.