Intraoperative dexamethasone alters immune cell populations in patients undergoing elective laparoscopic gynaecological surgery.

BACKGROUND: Anaesthetists use dexamethasone principally for its anti-emetic effect. The purpose of this study was to characterize the effects of a single intraoperative dose of dexamethasone on cellular and metabolic components of the immune system in patients undergoing laparoscopic surgical procedures. METHODS: In this prospective double-blind trial, female patients undergoing elective major laparoscopic surgery were randomized to receive saline (Control group, n =16) or dexamethasone 4 mg (Dexamethasone group, n =16) i.v. after the induction of anaesthesia. Inflammatory markers and immune cell counts were examined at 24 and 48 h and 6 weeks after surgery. The changes from baseline preoperative values were compared between groups using a Mann-Whitney U -test, and linear mixed models were used to validate the findings. RESULTS: No differences in concentrations of serum glucose and interleukin-6 were observed between groups after surgery. The increase in C-reactive protein concentration at 24 h after surgery was greater in the control group [median (interquartile range), 33 (25-65) vs 17 (7-26) mg dl -1 ; P =0.018]. Extensive changes in the counts of white cells, including most lymphocyte subsets, were observed 24 h after surgery, and dexamethasone appeared to attenuate most of these changes. Changes at 48 h and 6 weeks did not differ between groups. CONCLUSIONS: In female patients undergoing elective laparoscopic gynaecological surgery, dexamethasone administration appears to attenuate inflammation and to alter immune cell counts at 24 h, with no effects identified after this time. The importance of these changes for postoperative immune function is unknown. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Registry (ACTRN12608000340336).

A randomised double-blind trial of phenylephrine and metaraminol infusions for prevention of hypotension during spinal and combined spinal-epidural anaesthesia for elective caesarean section.

Prophylactic vasopressor administration is commonly recommended to reduce maternal hypotension during spinal anaesthesia for caesarean section. Metaraminol has undergone limited investigation in obstetric anaesthesia for this purpose, particularly in comparison with phenylephrine. In this multicentre, randomised, double-blind, non-inferiority study, we compared prophylactic phenylephrine or metaraminol infusions, started immediately after spinal anaesthesia, in 185 women who underwent elective caesarean section. Phenylephrine was initially infused at 50 µg.min-1 , and metaraminol at 250 µg.min-1 . The primary outcome was the difference in umbilical arterial pH between groups; secondary outcomes included other neonatal acid-base measures, and maternal haemodynamic changes. The mean (SD) umbilical arterial pH was 7.28 (0.06) in the phenylephrine group vs. 7.31 (0.04) in the metaraminol group (p = 0.0002). The estimated mean (95%CI) pH difference of 0.03 (0.01-0.04) was above the pre-determined lower boundary of clinical non-inferiority, and also met the criterion for superiority. Umbilical artery lactate concentration was 2.8 (1.2) mmol.l-1 in the phenylephrine group vs. 2.3 (0.7) mmol.l-1 in the metaraminol group (p = 0.0018). Apgar scores did not significantly differ between groups. There was a higher incidence of hypotension, defined as systolic arterial pressure < 90% baseline, in the phenylephrine group; there was a higher incidence of hypertension and severe hypertension (systolic arterial pressure > 110% and > 120% baseline, respectively) in the metaraminol group. There was no significant difference between groups in the incidence of nausea, vomiting or maternal bradycardia. We conclude that, when used as an infusion to prevent hypotension after spinal anaesthesia for elective caesarean section, metaraminol is at least non-inferior to phenylephrine with respect to neonatal acid-base outcomes.

A randomised comparison of parecoxib versus placebo for pain management following minor day stay gynaecological surgery.

At therapeutic concentrations, parecoxib selectively inhibits the cyclo-oxygenase-2 enzyme. We investigated the impact of a single preoperative dose of parecoxib on pain relief following minor gynaecological surgery. Ninety women undergoing uterine dilatation and curettage, with or without hysteroscopy, were randomised to receive either 40 mg of parecoxib intravenously or a saline placebo prior to induction of standardised general anaesthesia. Exclusion criteria included a preoperative history of renal dysfunction or hypertension and the preoperative use of anti-inflammatory or opioid medication. The primary endpoint was the pain score during recovery. There was no difference in global pain scores or area under the curve for pain scores in the recovery area. Pain scores with coughing one hour after surgery were low in both groups but significantly lower after parecoxib (median 2 [interquartile range 0 to 4] parecoxib group vs. 2 [interquartile range 0 to 6] placebo group, P = 0.037). The 24 hour Quality of Recovery score did not differ significantly between groups but the parecoxib group was less likely to experience headache at 24 hours postoperatively (12 vs. 38%, P = 0.007) and reported complete satisfaction more frequently (78 vs. 57%, P = 0.042). The preoperative administration of parecoxib was associated with a significant but small decrease in dynamic pain scores one hour postoperatively. Women who received preoperative parecoxib had a lower incidence of postoperative headache and higher satisfaction.

Acute magnesium toxicity in an obstetric patient undergoing general anaesthesia for caesarean delivery.

Magnesium is commonly used in the prevention of eclampsia. Reports of acute toxicity are rare and we are not aware of detailed management algorithms. We present a case of acute magnesium toxicity presenting as ventilatory impairment and failure to rouse adequately from general anaesthesia. The patient was managed with controlled ventilation, further sedation, intravenous calcium gluconate, forced diuresis and dextrose-insulin infusion. We present a guideline for the management of life-threatening magnesium toxicity and discuss measures that may prevent future similar occurrences.

Analgesia after caesarean delivery.

As the number of women giving birth by caesarean increases throughout most of the developed world, so too is research into postoperative pain relief for these women. Like most other post-surgical populations, the new mother needs effective pain relief so that she can mobilise early but she also has the added responsibility of needing to care for her newborn baby. There is no 'gold standard' for post-caesarean pain management; the number of options is large and the choice of method is at least partly determined by drug availability, regional and individual preferences, resource limitations and financial considerations. Most methods rely on opioids, supplemented with anti-inflammatory analgesics, nerve blocks or other adjunctive techniques. The aim of this review is to detail commonly used opioid-based methods and to review the evidence supporting non-opioid methods, when incorporated into a multimodal approach to post-caesarean pain management. Areas of promising research are also discussed.