Combined spinalepidural versus epidural analgesia in labour (review) By Neda Taghizadeh
Cochrane review Cochrane collaboration was founded in 1993 and is named after Archie Cochrane (1909-1988), British medical researcher who believed as resources will always be limited, evidence from randomised controlled trials (RCT) should be used in decision making. Independent nonprofit organization consisting of a group of 28000 volunteers in more than 100 countries. The group produces up to date systemic reviews of RCTs of health care interventions, which it publishes in the Cochrane library. It has a seat on the world health assembly to provide input into WHO resolutions.
history This review was published originally in 2007, authors: Dr Hughes, Prof. Simmons, Dr Brown and Dr Cyna and looked at 14 trials with 2047 women. Later it was updated in 2009, authors : A/ Prof. Simmons, Dr Cyna, A/ Prof. Dennis, Dr Hughes and looked at 19 trials with 2658 women. The latest version published in 2012, authors: A/Prof, Simmons, Dr Taghizadeh, A. Prof. Dennis, Dr Hughes and Dr Cyna looks at 27 trials with 3274 women.
background Epidural is the most effective pain relief in labour and is used in 25% of labouring women in the UK and in 58% in USA. Traditional epidural (at least 0.25% bupivacaine) has been associated with prolonged labour, use of oxytocin and increased incidence of instrumental delivery. CSE was introduced to decrease these and increase mobility and also faster onset which in turn improve maternal satisfaction.
CSE Involves injection of an analgesic or local anaesthetic drug or both, into the intrathecal space immediately before or after epidural catheter placement. Typically involve needle through needle technique It is claimed to provide the benefits of both spinal and epidural including faster onset, more reliable analgesia, minimal motor blockade, improved maternal mobilisation, lower maternal and cord blood local anaesthetic concentration and higher patient satisfaction,
Search method Cochrane pregnancy and child birth group trials register by contacting Trial Search Co-ordinator. Quarterly searches of Cochrane central register of controlled trials Weekly search of MEDLINE and EMBASE. Hand search of 30 journals and the proceedings of major conferences. Weekly search of another 44 journals (current awareness alert) All published randomized control trials (RCT), involving comparison of CSE vs Epidural initiated in first stage of labour were included.
Data collection and analysis 3 review authors independently assessed the trials for inclusion. Any disagreement was resolved through discussion or if required by consultation with a fourth person. A form was used to extract data. Data was entered into REVIEW MANAGER SOFTWARE (Rev Man 2011) and checked for accuracy. Unclear information: we attempted to contact the authors
Primary outcome Mean time and sd from request of analgesia to the time she felt pain relief was satisfactory Mean time and sd from CSE or Epidural injection to satisfactory pain relief. No. of women after 10 min from first injection experiencing satisfactory pain relief. No. of women satisfied with labour analgesia No. of women who were mobile No. of women with dural puncture headache or known dural tap requiring blood patch No of women with instrumental delivery or C- section No of women with any complication requiring intervention such as pruritus, urinary retention, N,V, hypotension, respiratory depression, sedation, also fever persistent paresthesia, high block,etc..
For the neonate No. with apgar less than 7 at 5 min. No admitted to neonatal unit and reason for admission. Economic consideration Cost of hospital stay
Secondary outcomes No. of women requiring augmentation of labour at any time. No. of women requiring augmentation after analgesic intervention. No. having normal vaginal delivery. No. requiring GA for C-section after analgesic intervention. No. requiring long term follow up for any reason eg meningitis, paralysis, foot drop, backache, ICU admission, etc.
For the neonate Mean PH and sd for umbilical artery, vein. No of neonate with Apgar less than 8 at 5 min. ECONOMIC CONSIDERATION Length of hospital stay No. requiring re admission within 1 month No. requiring ongoing follow up after discharge.
RISK OF BIAS ASSESSMENT Random sequence generation (selection bias) Allocation concealment (selection bias) Blinding of participants, personnel and outcome assessment (performance bias and detection bias) Incomplete outcome data (attrition bias) Selective reporting (reporting bias) Risk of bias : low, unclear or high
statistics For dichotomous data, risk ratio with 95% confidence interval used For continuous data, mean difference if outcomes were measured the same way between trials or standardised mean difference to combine trials that measured the same outcome, but used different methods. There was no cluster randomised trials for inclusion.
Main results 27 trials involving 3274 women met inclusion criteria. 26 outcomes in 2 sets of comparisons involving CSE vs. traditional epidurals and CSE vs. low dose epidural were analyzed.
Methods and techniques All studies had informed consent and ethics committee approval. 18 studies mentioned fluid preload with crystalloid (ranging from 500, 1000 or in between, or 10 ml/kg or 15 ml/kg) All single space, needle-through-needle technique Position of the mother variable ( sitting, lateral or not stated.
participants All included healthy women obstetrically uncomplicated, mostly singleton, at term. Stage of cervical dilatation highly variable:4 studies up to 4 cm, 11 studies up to 5cm, 3 studies up to 6 cm, 1 study up to 7cm or not stated. Intervention: 6 comparisons made LA/opioid CSE vs traditional E:3 trials (846) and low dose E: 18trials (2086) Opioid CSE vs. traditional E; 4 trials (229) and low dose E: 2 trials (102)
Variation on cse Bupivacaine(1.25-3.75mg) in combination with fentanyl (5-25 mic) or sufentanil (1.5-5 mic) A common technique is to use 2.5 mg of bupivacaine plus 25 mic of fentanyl (6 studies). Opioid only : 3 trials of 25 mic of fentanyl, 1trial of fentanyl and morphine (0.25 mg),1 trial of morphine, 3 trial of sufentanil.
Cse techniques used
Variation of epidural Traditional used at least 0.25% bupivacaine boluses at some stage (8 trials) with volume ranging from 6-12 ml, one study used lignocaine 2% 10ml. Low dose epidural uses bupivacaine (0.0625% to 0.125%) in combination with fentanyl (25-75 mic) or sufentanil(5-10mic) to a total volume 10-20 mls to establish the block (16 trials). Maintenance either after return of pain in both groups or infusion of low dose LA with opioid, or PCEA (5 studies).
Epidural techniques used
Neonatal outcome 21 studies included neonatal assessment. Apgar score was used as an outcome measure 4 studies gave information on apgar less than 7 and 4 studies on apgar less than 8 at 5 min. Cord blood gas analysis used in 5 studies 1 study only included admission to special care neonatal unit In 1 study, there was a stillbirth in CSE group with cord around the neck. 2 studies looked at foetal bradycardia as primary outcome.
RESULTS
CSE vs. traditional epidural 5 outcomes showed a significant difference. CSE was more favourable in relation to speed of onset of analgesia from time of injection (MD -2.87 minutes. CI -5.07 to - 0.67). Reduced need for rescue analgesia RR0.31 (95% CI 0.14-0.70). Need for instrumental delivery RR 0.81. (95% CI 0.67-0.97). CSE was associated with less urinary retention RR0.86 ( 95% CI 0.79-0.95). CSE was associated with slightly lower umbilical cord PH based on 1 study, 55 women, involving intrathecal morphine. With borderline statistical significance (MD -0.03; 95%CI -0.06-00.00.)
Time from first injection to analgesia
Instrumental delivery
Need for rescue analgesia
Urinary retention
Not significant Number of women who mobilized, post dural puncture headache, pruritus, nausea and vomiting, hypotension, rate of C-section. Neonatal outcome, umbilical arterial PH, apgar score less than 7 at 5 min., number of admission to neonatal unit.
CSE versus low dose epidural Faster onset of effective analgesia in CSE group, mean time of onset of effective analgesia was -5.42 min. (95% CI -7.26 to -3.59) Effective analgesia at 10 min RR1.94 in favour of CSE.(95% CI 1.49-2.54). More pruritus in CSE group (average RR 1.8; 95%CI 1.22 to 2.65). No significant difference in maternal satisfaction, need for rescue analgesia, mobilisation in labour, incidence of post dural puncture headache, known dural tap, blood patch, urinary retention, N&V, hypotension, need for labour augmentation, mode of delivery or any of neonatal outcomes ie umb. cord PH, Apgar score,neonatal unit admissions.
Time from first injection to analgesia
pruritus
Number with analgesia 10 min. after first injection
Adverse events 1 case of meningitis reported in CSE group which responded to antibiotics. 1 case of reflex sympathetic pain of the foot reported in CSE group that required 2 paravertebral blocks to resolve.
conclusion
Little difference between cse and low dose epidural with similar maternal satisfaction, slightly faster onset of CSE but more pruritus. It is important that anaesthetists to be skilled at performing both methods as depending on the clinical situation, one method may be advantageous. Traditional epidural (0.25% or greater) has higher incidence of urinary retention, rescue interventions and instrumental delivery, so either CSE or low dose epidural is preferable.
conclusion Regarding foetal heart rate changes from these studies there was no difference in C-section rate or the neonatal outcomes in terms of Apgar score at 5 min. or the need for neonatal unit admission. Proposed benefits of CSE including increased mobility and effect on mode of delivery hasn t been proved when compare with low dose epidural. Maternal satisfaction seems to be equal as faster onset of analgesia favours CSE while more pruritus favours epidural.
conclusion Randomised controlled trials are not the best means of assessing differences in the rate of rare complications. This review include 3200 women which is insufficient to assess rare outcomes. However as part of large studies, long term outcomes should still be collected for future benefits but at present have to rely on case reports.
Future studies Trials should include time taken from maternal request to effective analgesia which is more relevant to women in labour, also extra time required to get CSE ready may be relevant. No study has mentioned number required to be converted to GA for C-section With CSE epidural catheter may not be tested, with resultant intravascular injection, on the other hand may provide denser block and better analgesia. A large study can provide information about conversion to GA. Economic aspects of both types hasn t been addressed so far.
THE END Many thanks to A/professors Scott Simmons and Alicia Dennis.