Is magnesium sulfate by the intrathecal route efficient and safe?

The polypharmacological approach to the treatment of postoperative pain has become routine in an attempt to minimize the adverse side effects of opioids. Magnesium sulphate is a noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) receptor and thus can modify nociceptive modulation. Intravenous administration of magnesium sulphate can improve postoperative analgesia and decrease the requirement for postoperative opiates, but the effects are inconsistent and have not been reliably accompanied by a reduction in the incidence of morphine-related adverse events. Several studies have shown that the administration of magnesium by the intrathecal route is safe and, in combination with opiates, extends the effect of spinal anaesthesia in both animal and human studies. The analysis of these studies justifies further investigation of the use of magnesium sulphate by the intrathecal route.

The effect of adding intrathecal magnesium sulphate to morphine-fentanyl spinal analgesia after thoracic surgery. A prospective, double-blind, placebo-controlled research study.

BACKGROUND: We investigated whether intrathecally magnesium sulphate added to morphine and fentanyl reduces patients' postoperative analgesia requirements and prolongs spinal opioid analgesia after thoracotomy. METHODS: In a single-center, prospective, placebo-controlled, double-blind trial, we enrolled 58 adult patients undergoing elective posterolateral thoracotomy. Patients were randomized to receive either 25 µg of fentanyl citrate (0.5 mL)+300 µg of morphine+1.0 mL of preservative-free 0.9% sodium chloride (Group S) or 25 µg of fentanyl citrate (0.5 mL)+300 µg of morphine+50mg of magnesium sulphate 5% (1.0 mL) (Group MgSO(4)) for intrathecal analgesia. Opioid consumption and postoperative pain were assessed for 36 hours. RESULTS: VAS pain scores at rest and on coughing were similar in all groups. The total 36-h intravenous morphine requirements were significantly lower in group MgSO(4) (14 [9.50-26.50] mg vs. 33 [30-41] mg, p<0.001); i.e. 57% less for the group MgSO(4). The total dose of intravenous morphine administered during titration was significantly lower in this group (4 [2-8] mg vs. 8 [6-10] mg, p=0.001). Morphine consumption was significantly lower in the group MgSO(4) at intervals 0-12, 12-24 and 24-36 h. The number of patients requiring titration was significantly lower in group MgSO(4) (68% vs. 96%, p=0.001). There is no difference in opioid side effects. No patient experienced side effects resulting from lumbar puncture, or neurological deficit or signs of systemic magnesium toxicity. CONCLUSION: We found that in patients undergoing pulmonary resection with elective posterolateral thoracotomy, magnesium sulphate (50mg), when added to spinal morphine analgesia reduces postoperative morphine requirements, the number of patients requiring morphine titration without increasing opioid side effects.

Cystic mesenchymal hamartoma of the liver report of a case and review of the literature.

Mesenchymal Hamartoma (MH) of the liver constitutes the third or the fourth most common tumour of the liver in childhood and occurs most commonly in the first two years of life. It is often misdiagnosed clinically as a malignant tumour because of its rapid increase in size within a short period of time, or as a hepatic collections or abscess because of its cystic appearance. Although a benign lesion, MH may cause heart failure due to arteriovenous shunts, or death as a result of respiratory complications. A typical case of MH was recently encountered in a 6-years-old-boy. The patient presented with progres sive abdominal distension; surgery revealed a large mass arising from the right lobe of the liver. The mass was predominantly formed by fluid collections. Loose mesenchymal tissue and branched, tortuous bile ducts were the key diagnostic features. When predominantly cystic, MH may mimic lymphangioma both grossly and microscopically. Prudent examination of the cystic structures can establish a correct diagnosis.

Changes in ventilation, oxygen uptake, and carbon dioxide output during recovery from isoflurane anesthesia.

Recovery from inhalation anesthesia is often marked by the occurrence of postoperative tremor that resembles shivering, which is known to be associated with an increase in oxygen uptake (VO2), CO2 output (VCO2), and minute ventilation (VE). This study determined the time course of the ventilatory changes observed during the first hour of recovery from isoflurane anesthesia. Ten patients (ASA PS 1) scheduled for minor orthopedic surgery (knee arthroscopy) were included in this study. Anesthesia was induced with thiopental (5 mg/kg) and maintained with 70% N2O and isoflurane (1-2%) in oxygen, allowing spontaneous ventilation. In the recovery room, after N2O had been discontinued, patients were connected to a Beckman Metabolic measurement cart, which allowed a continuous monitoring of VE, VO2, VCO2, and PETCO2. Postoperative tremor was observed in all patients within 7.1 +/- 1.2 min (mean +/- SEM) after isoflurane discontinuation and was associated with a marked increase in the following: VO2, from 173 +/- 26 ml/min at the end of anesthesia to 457 +/- 88 ml/min; VCO2, from 149 +/- 18 ml/min at the end of anesthesia to 573 +/- 98 ml/min; and VE, from 6.8 +/- 0.7 l/min at the end of anesthesia to 16.6 +/- 2.8 l/min (values obtained 20 min after isoflurane discontinuation). In three patients during intense shivering, VO2, VCO2, and VE reached peak values higher than 800 ml/min, 1,300 ml/min and 30 l/min, respectively. This study shows that postoperative tremor following isoflurane anesthesia may be associated with prolonged and large increases in oxygen uptake, CO2 output, and minute ventilation.