Cardiac output changes with phenylephrine and ephedrine infusions during spinal anesthesia for cesarean section: A randomized, double-blind trial.

Hypotension is a common side effect of spinal anesthesia. Phenylephrine and ephedrine are the two most frequently used vasopressors to treat spinal hypotension during cesarean delivery. In this randomized double-blind study, we aimed to evaluate cardiac output (CO) changes with phenylephrine or ephedrine infusions titrated to maintain baseline systolic blood pressure (bSBP) during spinal anesthesia. Women (n = 40) scheduled for elective cesarean delivery received either phenylephrine 100 µg/min or ephedrine 5 mg/min infusions. Baseline hemodynamics (cardiac output, heart rate, systolic blood pressure) were recorded in the left lateral tilt position before fluid preload, and recorded every minute after spinal anesthesia until delivery. Umbilical cord blood gases were analyzed within 5 minutes of delivery. Good systolic blood pressure control was attained in both groups with minimal periods of hypotension (SBP <80% of bSBP) or hypertension (SBP >120% of bSBP). Cardiac output and heart rate increased over time with ephedrine, but decreased with phenylephrine. The maximum increase in CO from the baseline was 12%, in the ephedrine group, and this occurred 20 minutes after spinal injection. Cardiac output fell by more than 17% in the phenylephrine group, maximal at 10 minutes following spinal injection. Despite good systolic blood pressure control and increased cardiac output with ephedrine, administration of ephedrine was associated with significantly more fetal acidosis [Median (Interquartile range, IQR) UApH - phenylephrine = 7.33 (7.31-7.34) and ephedrine = 7.22 (7.16-7.27), P < .05].

The effect of serial in vitro haemodilution with maternal cerebrospinal fluid and crystalloid on thromboelastographic (TEG(®) ) blood coagulation parameters, and the implications for epidural blood patching.

Epidural blood patches may be used to treat post-dural puncture headache following accidental dural puncture in parturients. Their mode of action and the optimum volume of blood for injection remain controversial, with the interaction between injected blood and cerebrospinal fluid unknown. We aimed to establish the effects of serial haemodilution of whole blood with cerebrospinal fluid from 34 pregnant patients compared with serial haemodilution with Hartmann's solution, using the thromboelastogram. Haemodilution with either cerebrospinal fluid or Hartmann's solution had significant procoagulant and clot destabilising effects, enhanced with progressive haemodilution up to 30%. The effect of cerebrospinal fluid was greater compared with Hartmann's solution (p < 0.001). Cerebrospinal fluid led to a mean (95% CI) decrease in r-time by 2.4 (1.6-3.2) min, a decrease in k-time by 0.6 (0.4-0.8) min, an increase in alpha angle by 7.3 (5.5-9.0)°, and a decrease in maximum amplitude by 2.0 (0.6-3.4) mm. This may have implications for epidural blood patch, as success may be reduced near the time of dural puncture when cerebrospinal fluid leak is at its greatest, and large volumes of blood may be required to reduce haemodilution and clot destabilisation by cerebrospinal fluid. In addition, blood patching should be performed at the level of the dural puncture in order to ensure that the maximum volume of blood comes into contact with the cerebrospinal fluid.

How UK obstetric anaesthetists assess neuraxial anaesthesia for caesarean delivery: national surveys of practice conducted in 2004 and 2010.

BACKGROUND: There is much interest in optimal methods of assessing neuraxial block before caesarean delivery. Although cold sensation is commonly used, some evidence suggests that the risk of intraoperative pain may be reduced by assessing light touch. We aimed to determine how neuraxial anaesthesia was managed perioperatively, and whether changes in clinical practice reflected the differing evidence in the literature over six years. METHODS: A survey was sent to UK consultant OAA members in 2004, asking how neuraxial block was assessed before caesarean delivery, what was documented, what information was given to the patient, and postoperative follow-up. The survey was repeated in 2010. RESULTS: Compared to all other methods of assessing neuraxial block, ethyl chloride was the most popular in 2004 (71.8%, 95% CI 68.3-75.0, P < 0.0001) and 2010 (74.6%, 95% CI 70.8-78.3, P < 0.0001). There was a non-significant increase in light touch use from 54% to 60.1%. The upper level of block varied with the modality tested. There was a significant increase in respondents testing with light touch to T5. CONCLUSIONS: Methods of assessing neuraxial block differed from those recommended in the literature. The wide range of modalities, methods of testing and targeted sensory levels suggest that clearer recommendations on best practice for assessment and documentation of neuraxial block before caesarean delivery are required.

Dexamethasone is a cost-effective alternative to ondansetron in preventing PONV after paediatric strabismus repair.

This study evaluated the antiemetic efficacy, cost-effectiveness and clinical utility of prophylactic ondansetron and dexamethasone compared with placebo in the prevention of postoperative nausea and vomiting (PONV) in 135 children (2-15 yr, ASA I-II) undergoing strabismus repair. After induction with halothane and nitrous oxide in oxygen or i.v. thiopental, the children received i.v. dexamethasone 1 mg kg(-1) to a maximum of 25 mg, ondansetron 100 microg kg(-1) to a maximum of 4 mg or placebo (n=45). Episodes of PONV were recorded for the first 24 h after the operation. True outcome measures (parental satisfaction score, duration of stay in the postanaesthesia care unit and fast tracking time), therapeutic outcome measures (number needed to prevent (NNTP) PONV) and the cost to benefit a child with each drug were analysed. The incidence and severity of PONV in the first 24 h were significantly less in the dexamethasone and ondansetron groups than in the placebo group (P<0.05). The incidence (P=0.04) and severity (P=0.03) of PONV at the 6-24 h epoch were significantly less in the dexamethasone group than in the ondansetron group. Recovery time (P=0.07), fast tracking time (P=0.6), parental satisfaction scores (P=0.08) and NNTP PONV were comparable (NNTP=2) in both the ondansetron and the dexamethasone group. The cost to benefit a child with dexamethasone was approximately 22 times less than that of ondansetron.

Intra-ocular pressure and haemodynamic changes after tracheal intubation and extubation: a comparative study in glaucomatous and nonglaucomatous children.

This prospective, controlled study was conducted to compare the effects of tracheal intubation and extubation on intra-ocular pressure changes and haemodynamic parameters in paediatric patients with and without glaucoma. The children were scheduled for intra-ocular surgery. Twenty children with normal intra-ocular pressure and 15 with glaucoma were studied. A standardised general anaesthetic was administered to both groups. After 5 min of anaesthesia, intra-ocular pressure, heart rate and noninvasive blood pressure were measured. These measurements were repeated 30 s and 2 min after tracheal intubation. Further measurements were taken before, and 30 s and 2 min after extubation. The increase in intra-ocular pressure after intubation was greater in the glaucomatous group than in the normal group. The increase in intra-ocular pressure was greater after extubation than intubation in both groups, but was similar in the two groups. However, because of the already increased intra-ocular pressure in glaucomatous children, they may be at an increased risk of visual damage after intubation and extubation.