The effect of colloid preload versus prophylactic ephedrine administration on QTc intervals during cesarean delivery: A randomized controlled study

Perioperative hypotension and use of vasoactive agents in non-cardiac surgery: A scoping review

BACKGROUND

Perioperative hypotension is common and associated with adverse patient outcomes. Vasoactive agents are often used to manage hypotension, but the ideal drug, dose and duration of treatment has not been established. With this scoping review, we aim to provide an overview of the current body of evidence regarding the vasoactive agents used to treat perioperative hypotension in non-cardiac surgery.

METHODS

We included all studies describing the use of vasoactive agents for the treatment of perioperative hypotension in non-cardiac surgery. We excluded literature reviews, case studies, and studies on animals and healthy subjects. We posed the following research questions: (1) in which surgical populations have vasoactive agents been studied? (2) which agents have been studied? (3) what doses have been assessed? (4) what is the duration of treatment? and (5) which desirable and undesirable outcomes have been assessed?

RESULTS

We included 124 studies representing 10 surgical specialties. Eighteen different agents were evaluated, predominantly phenylephrine, ephedrine, and noradrenaline. The agents were administered through six different routes, and numerous comparisons between agents, dosages and routes were included. Then, 88 distinct outcome measures were assessed, of which 54 were judged to be non-patient-centred.

CONCLUSIONS

We found that studies concerning vasoactive agents for the treatment of perioperative hypotension varied considerably in all aspects. Populations were heterogeneous, interventions and exposures included multiple agents compared against themselves, each other, fluids or placebo, and studies reported primarily non-patient-centred outcomes.

Granisetron or ondansentron to prevent hypotension after spinal anesthesia for elective cesarean delivery: A randomized placebo-controlled trial

STUDY OBJECTIVE

This study aimed to compare the effects of high doses of ondansetron and granisetron before spinal anesthesia on hemodynamic parameters in patients undergoing elective cesarean section.

DESIGN

A double-blinded randomized placebo-controlled trial.

SETTING

Operating room.

PATIENTS

A total of 120 parturients with term pregnancy undergoing elective cesarean section with combined spinal-epidural anesthesia were included.

INTERVENTIONS

Three groups (n = 40 for each group) were formed by randomization. Five minutes before the anesthesia procedure, Group I received 8 mg intravenous (IV) ondansetron diluted in 10 ml normal saline, Group II received IV 3 mg granisetron diluted in 10 ml normal saline, and Group III received IV 10 ml normal saline.

MEASUREMENTS

Following intrathecal drug administration, intraoperative hemodynamic changes were recorded every 2 min for 20 min and then every 5 min until the end of the operation.

MAIN RESULTS

Twenty patients (50%) in Group I, 12 patients (30%) in Group II, and 29 patients (72.5%) in Group III had hypotension requiring treatment with IV ephedrine (P = 0.001). The ephedrine requirement in Group III was significantly higher than in Groups I (P = 0.033) and II (P < 0.001). Also, the ephedrine requirement in Group II was lower than in Group I, but the difference was not statistically significant (P = 0.055). The mean arterial pressure for the three groups differed in the 10th, 18th, and 60th minutes. The number of patients with nausea or vomiting was lower in Groups I and II than in Group III (P < 0.001). At 5 min, the Apgar scores were higher than 8 for all neonates. Postoperative scores for the visual analogue scale were similar for all groups.

CONCLUSIONS

It was concluded that prophylactic IV administration of 3 mg of granisetron or 8 mg of ondansetron before spinal anesthesia results in a significantly lower ephedrine requirement compared to placebo.

The relationship between gestational week and QT dispersion in cesarean section patients undergoing spinal anaesthesia: A prospective study

BACKGROUND

Pregnancy affects the cardiovascular system, particularly the cardiac conduction system, thereby increasing the susceptibility of patients towards arrhythmia. QT interval results in ventricular arrhythmias, predominantly polymorphic ventricular tachycardia. The present study was planned to investigate the relationship between a gestational week and QT dispersion in cesarean section patients undergoing spinal anaesthesia.

METHODS

The study included 40 patients between the ages of 18 and 45 who had no symptoms of anaemia and undergoing elective cesarean section. The patients were separated into two groups based on the gestational week as Group I <39 weeks and Group II ≥39 weeks. The patient was given a sitting position and the puncture site was cleansed with 10% povidone-iodine antiseptic solution. After placing a sterile drape on the patient, the subarachnoid space was punctured through an appropriate vertebral space (L3-L4 or L4-L5) using a pencil-point 25G spinal needle, followed by intrathecal injection of 12.5 mg (2.5 mL) 5% hyperbaric bupivacaine hydrochloride. Electrocardiographic (ECG) records were obtained both preoperatively and at 1, 5, and 10 minutes after spinal block, and the QT, QTc, QTd, and corrected QTd (QTcd) intervals were estimated using Bazett's formula.

RESULTS

There was no significant difference between the two groups within the QT and QTc intervals. QTcd measured after post-operative was significantly higher in Group II (P = .007).

CONCLUSION

The results indicated that spinal anaesthesia may prolong the QTdc interval in patients with a gestational week of ≥39 weeks undergoing cesarean section.

Prevention of hypotension after spinal anaesthesia for caesarean section: a systematic review and network meta-analysis of randomised controlled trials

Spinal anaesthesia for caesarean section commonly causes maternal hypotension. This systematic review and network meta-analysis compared methods to prevent hypotension in women receiving spinal anaesthesia for caesarean section. We selected randomised controlled trials that compared an intervention to prevent hypotension with another intervention or inactive control by searching MEDLINE and Embase, Web of Science to December 2018. There was no language restriction. Two reviewers extracted data on trial characteristics, methods and outcomes. We assessed risk of bias for individual trials (Cochrane tool) and quality of evidence (GRADE checklist). We assessed 109 trials (8561 women) and 12 different methods that resulted in 30 direct comparisons. Methods ranked by OR (95%CI) from most effective to least effective were: metaraminol 0.11 (0.04-0.26); norepinephrine 0.13 (0.06-0.28); phenylephrine 0.18 (0.11-0.29); leg compression 0.25 (0.14-0.43); ephedrine 0.28 (0.18-0.43); colloid given before induction of anaesthesia 0.38 (0.24-0.61); angiotensin 2, 0.12 (0.02-0.75); colloid given after induction of anaesthesia 0.52 (0.30-0.90); mephentermine 0.09 (0.01-1.30); crystalloid given after induction of anaesthesia 0.78 (0.46-1.31); and crystalloid given before induction of anaesthesia 1.16 (0.76-1.79). Phenylephrine caused maternal bradycardia compared with control, OR (95%CI) 0.23 (0.07-0.79). Ephedrine lowered umbilical artery pH more than phenylephrine, standardised mean difference (95%CI) 0.78 (0.47-1.49). We conclude that vasopressors should be given to healthy women to prevent hypotension during caesarean section with spinal anaesthesia.