Obstetric Anaesthesia UpdateInfomed Update for the General Anaesthetist 20th June 2019

James EldridgePortsmouth Hospitals NHS Trust

Plan

• Labour Analgesia

➢ Opiate analgesia

➢ Epidural analgesia

➢ NRFit

➢ Enhanced recovery

• Managing complications and emergencies

➢ Airways

➢ Hypotension and spinal anaesthesia

➢ Post dural Puncture headache

➢ Haemorrhage: fibrinogen and tranexamic acid

Opiate analgesia

Diamorphine vs Pethidine

• 7.5mg IM diamorphine vs 150mg IM pethidine

• 484 women

Wee IJOA May 2012

Better pain relief: Diamorphine p

Remifentanil2014 - available in 50% of UK delivery suites

OAA survey 154 Clark

Remifentanil

Pharmaco-kinectics:

• Rapid onset & short duration

o Non-pregnant context-sensitive half-time 3 mins

o Effect site peak conc at 1-2 mins

o Large variations in pharmacokinetics in pregnant women (generally lower plasma concentrations)

• Rapid and extensive transfer across the placenta

o UV to MA ratio of 0.88

• Rapid fetal metabolism

o UA/UV 0.29

Remifentanil

Used across Europe and North America

Side effects– Sedation

– Nausea

– Reduced FHR variability

–Maternal hypoxia (30%)– 5% of labour with Sats < 90%

Technique• 1-to-1 care

• No opioid within 4 hours

• Dedicated iv (care with BP cuff)

• PCA with bolus dose of 40mcg and lockout of 3 min

• Continuous pulse-oximetry.

• Give O2 if SpO2 < 94% on air.

• 30 minutely observations of respiratory rate, sedation score and pain scores.

• Flush the cannula

Editorial Machatuta Anaesthesia 2013

Remifentanil

Efficacy:

• Modest pain relief (37 studies but mostly poor quality)

o Slightly better analgesia than nitrous oxide

o Better than pethidine

o Inconclusive compared to other opiates

o Not as effective as neuraxial analgesia (nb difference between pain and satisfaction scores)

o Reduced efficacy in late labour

• Most likely to be effective in early 1st stage of labour.

PCA Remifentanil vs epidural analgesia (RCT)Freeman BMJ 2015

1414 women recruitedo705 Epidural (various low dose

regimens)

o709 Remifentanil PCA

In the remifentanil group:o In women who received pain relief,

satisfaction poorer than with epidural

o Higher pain scores

o Lower peak analgesia

o Higher worst pain score

o More frequent Sat

o Four reported Resp depressions (Resp rate < 8bpm)

Freeman BMJ 2015

“Caregivers should be aware that serious respiratory complications

can occur during administration of remifentanil”

RESPITE Trial: Remifentanil PCA vs IM PethidineWilson 2018 Lancet

• Open-label, multicentre (14 units), RCT

• 400 women

• Pethidine (100mg/4 hours, max 400mg)

• Remifentanil (40mcg, 2 min lockout)

• Outcome – epidural conversion

Remifentanil PCA

PethidineIM

Number of women 201 199

Epidural conversion 39 (19%) 81 (41%)

Significant reduction in epidural conversion (RR 0.48, CI 0.34-0.66, P< 0.0001)

RESPITE Trial: Remifentanil PCA vs IM PethidineWilson 2018 Lancet

• Open-label, multicentre (14 units), RCT

• 400 women

• Pethidine (100mg/4 hours, max 400mg)

• Remifentanil (40mcg, 2 min lockout)

• Outcome – epidural conversion

Remifentanil PCA

PethidineIM

p-value

Number of women 201 199

Epidural conversion 39 (19%) 81 (41%)

RESPITE Trial: Remifentanil PCA vs IM PethidineWilson 2018 Lancet

• Open-label, multicentre (14 units), RCT

• 400 women

• Pethidine (100mg/4 hours, max 400mg)

• Remifentanil (40mcg, 2 min lockout)

• Outcome – epidural conversion

Remifentanil PCA

PethidineIM

p-value

Number of women 201 199

Epidural conversion 39 (19%) 81 (41%)

Muchatuta NA, Kinsella SM

BEWARE OCCASIONAL USERS / NEW STARTERSBEWARE COMPLACENCY

Epidural Analgesia

Randomised studies of epidural analgesia in labour40 RCT

• >11,000 women

• 34 epidural vs opiate

•7 epidural vs no pain relief

• (4 trials had more than 2 arms)

Anim-Somuah Cochrane DB 2018

RCTs of Epidural vs OpiateNo of trials No of

WomenEffect of epidural analgesia

Pain Scores 5 1133 Better pain reliefSMD* -2.64

CI -4.56-0.73

Satisfaction with pain relief

7 1911 Better satisfactionRR 1.44

CI 1.03-2.08

Caesarean section 33 10350 No differenceRR 1.07

CI 0.96 – 1.18

Assisted vaginal delivery

30 9948 Increased(only if pre2005 trials included)

RR 1.44CI 1.29 -60

Fever 9 4276 IncreasedRR 2.51

CI 1.67-3.77

Neonatal Admission to NICU

8 4488 No differenceRR 1.03

CI 0.95-1.12

Apgar score

Neuraxial analgesia and instrumental delivery

Low dose (≤ 0.1% bupivacaine)

• 18 RCT studies

• 2284 women

• Reduces instrumental deliveryOR 0.77 (CI 0.64-0.93)

Sultan IJOA May 2012

Neuraxial bolus or infusion and instrumental delivery

• Midwifery top-ups

• Epidural infusions

• PCEA +/- epidural infusion

• Programmed intermittent epidural bolus +/- PCEA

Kaynar Anesth Anal 1999

Neuraxial bolus or infusion and instrumental delivery

• Bolus techniques reduce total amount of local anaesthetic used

• Bolus techniques may reduce motor block and instrumental delivery rate

Capogna G, Anesth Analg. 2011George R, Anaesth Analg. 2013 (Meta-analysis)Bullingham A, Br J Anaesth. 2018Sng B, Cochrane Database Syst Rev. 2018 (Meta-analysis)

Optimal bolus volume

Individual responses of women to different programmed

intermittent epidural bolus (PIEB) volumes. Filled circle –ineffective PIEB volume; open circle –effective PIEB volume.

The estimated Effective Vol90 was 11.0 ml (95%CI 10.0–11.7)

Neuraxial analgesia to minimise instrumental delivery

• Low concentration solutions

• No background infusion

• Large volume epidural boluses (10 -11ml) • PIEB (Programmed Intermittent Epidural

Bolus)

• PCEA

Dural puncture in labour neuraxial analgesia

• Dural puncture improves analgesia• 25G PP needle – reduced unilateral block, improved

pain score

• CSE may reduce duration of 1st stage of labour• Controversial

• Not enough evidence to routinely recommend CSE labour analgesia

May have benefit for

• Women out of control (rapid onset)

• When re-siting epidurals (re-establish confidence)

Cappiello Anesth Analg. 2008; Simmons Cochrane Database Syst Rev. 2012

Dural Puncture Epidural vs epidural vs CSE

• DPE quicker than epidural

• DPE and CSE better sacral block

• DPE less fetal bradycardia than CSE

Chau Anesth Analg 2017

Epidural Space and BMI

Clinkscales IJOA 2007

Effect of epidural adipocytes on neuraxial anaesthesia and analgesia• Increased spread of block with

epidural anaesthesia

• Some increased spread of block with spinal anaesthesia

• Reduced chance of PDPH with spinal needle

• ? Reduced chance of PDPH with ADP with Tuohy needle

Kuntz Neurolgy 1992Lavi Neurolgy 2006Besov Headache 2010Jabbari Caspian J Intern Medicine 2013

Miu IJOA 2014Peralta Anesth Anal 2015Franz J Clin Anaesth 2017Song IJOA 2017

D’Angelo Anesthesiology 2014

Lumbar neuraxial ultrasound for spinal and epidural anesthesia: A systematic review and meta-analysis

• Identifies interspace more accurately

• Estimates depth of space accurately (+/- 3 mm)

• Improves efficacy of epidural

• Insufficient evidence to demostrate improvement in safety

Perlas 2016 Regional Anaes & Pain Med

NRFit ISO 80369 Series 6

80369-6 applications involve the use of medical devices to administer medications to and take samples from neuraxialsites (central nervous system including intracranial and spinal canal such as epidural and intrathecal), major peripheral nerve local anaesthetic blockade and continuous wound infiltration. This includes anaesthetic delivery, monitoring cerebro-spinal fluid (CSF) pressure, and removing CSF for therapeutic or diagnostic purposes.

ISO 80369 Standards

ISO Standard Use/Application Common Name

80369 – 2 Breathing systems and driving gases

80369 – 3 Enteral applications ENFit

80369 – 4 Urethral and urinary applications

80369 – 5 Limb cuff inflation

80369 – 6Neuraxial applications and major

regional anaesthesiaNRFit

80369 – 7Intravascular or hypodermic

applicationsLuer

International Organization for Standardization

Longer than Luer 20% smaller diameter Collared slip syringes

Luer

NRFit

(Yellow Colour)

NRFit ISO 80369 series: HOWTO Guide to the transition processISO 80369-6 Implementation of Neuraxial devices in the UK

01/06/2016

This paper is a case study of local practice and was reviewed by the NHS Small Bore Connector Clinical Advisory Group, who agreed that the information would be useful for other Trust when implementing new neuraxial connectors.

Dr Paul Sharpe, Chairman of NHS England Small Bore Connector Advisory Group. Consultant Anaesthetist University Hospitals of Leicester NHS Trust.

Dr Ian Shaw, Consultant Anaesthetist, Sheffield Teaching Hospitals NHS Trust.

Mr Pete Phillips, Director, Surgical Materials Testing Lab, Princess of Wales Hospital, Bridgend, South Wales

https://goo.gl/mERxFo

Step 1: Identify the disciplines affected by the conversion.

Step 2: Recruit staff to be involved in the changeover.

Step 3: Identify what kit you currently use.

Step 4: Check with your supplier that they will provide ISO 80369-6 versions of these devices.

Step 5: Ensure that your expert advisors have early sight of the new devices.

Step 6: Understand your off-label usage and ensure continued supply.

Step 7: Ensure that the pharmacy aseptic service has appropriate device options.

Step 8: Obtain senior management approval.

Step 9: Plan the timetable.

Step 10: Educate your staff.

Step 11: Provide demonstration sets

Step 12: Co-ordinate with suppliers

Step 13: Produce an exchange box for each clinical area

Step 14: Conversion Day

Step 15: Continue to provide support

Plan

• Labour Analgesia

➢ Opiate analgesia

➢ Epidural analgesia

➢ NRFit

➢ Enhanced recovery

• Managing complications and emergencies

➢ Airways

➢ Hypotension and spinal anaesthesia

➢ Haemorrhage: Fibrinogen and tranexamic acid

Enhanced Recovery

Portsmouth >50% elective and emergency CS discharged Day 1 since 2012

Early discharge after CS• Organisation

• Catheter removal, neonatal review, TTOs

• Expectation

• Mother

• Staff

• Community support

• Enhanced Recovery Techniques• Patient selection• Patient information• CHO loading• Neuraxial techniques• Delayed cord clamping• In theatre skin-to-skin contact• Analgesia paracetamol, NSAIDS, oral

opiates• Early oral intake• Early mobilisation• Early catheter removal

Post Dural Puncture

Headaches

MBRRACE 2014

Lessons

• Importance of thromboprophylaxis

• Importance of recognising PDPH

• Communication with GP

• Arranging follow-up until resolution

• Serious neurological symptoms require urgent referral and/or imaging

• If reduced LOC, transfer must be with appropriate medical (anaesthetic) involvement

MBRRACE 2014

Key points

• 5% PDPH are not postural• Incidence of PDPH

• >50% after 16/18G Tuohy• 1/3 dural puncture was not

recognised

• 1.5-11.2% after spinal anaesthesia

• Rare but serious complications include cerebral vein thrombosis and intracranial haemorrhage, cranial nerve palsies (VI & VII), seizures

• Bed rest may provide temporary relief (DVT prophylaxis)

• Simple analgesics should be used• Caffeine may be tried, but

treatment limited to 24 hours. Benefit limited to 4 hours. Possible ↑ risk of seizures.

• No or insufficient evidence for all other treatments apart from blood patch.

• This includes: other theophyllines, ACTH and analogues, steroids, triptans, gabapentinoids, DDAVP, methylergonovine, ondansetron, acupuncture, greater occipital nerve block, spenopalatine ganglion block, epidural morpine, epidural crystalloids, dextrans, HES, gelatin, or fibrin glue.

Key points

• Blood patch success rates• Early studies suggested >90%• Recent studies suggest

• complete success 30%• Complete or partial success 50-80%

• Timing• EBP

Airways

• OAA DAS guideline

Cause of Anaesthetic Deaths:Failed Airway Management

Total

Deaths associated with

failed airway

Confidential Enquiries into Maternal Deaths

OAA DAS obstetric airway guidelines 2015

Obstetric Anaesthetist Association

Criteria on whether to wake or proceed following failed intubation at caesarean section.From OAA DAS guideline

Proceed with surgery

• Spontaneous or controlled ventilation

• Consider muscle relaxation • Reduces laryngospasm, gastric insufflation, peak airway pressure and facilitates surgery.

• Most experienced surgeon

• Minimal fundal pressure

• Neonatal team informed

• Cricoid pressure until delivery

• 2nd generation SAD + gastric drain tube.

• Try to avoid further instrumentation of airway but:• Be prepared for front of neck

• If familiar consider fibreoptic scope

Hypotension and spinal anaesthesia

International Consensus on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia.Kinsella SM, Carvalho B, Dyer RA, Fernando R, McDonnell N, Mercier FJ, Palanisamy A, Sia ATH, Van de Velde M, Vercueil A; Consensus Statement Collaborators.

10 Recommendations …

1. ↓BP is common after spinals and is bad for mother and baby

2. Vasopressors should be used routinely and preferably prophylactically

3. α-agonists are most appropriate, although agents with a small amount of βactivity may have advantage.

4. Left lateral and fluid co-load should be used.

5. Aim to maintain sBP > 90% of baseline (with variable rate infusion of phenylephrine, starting at 25-50 mcg/min)

Anaesthesia 2018, 73,71-92

International Consensus on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia.Kinsella SM, Carvalho B, Dyer RA, Fernando R, McDonnell N, Mercier FJ, Palanisamy A, Sia ATH, Van de Velde M, Vercueil A; Consensus Statement Collaborators.

10 Recommendations …

6. Maternal heart rate is a surrogate for cardiac output - ↑HR &↓HR should be avoided

7. If ↓HR consider ephedrine. If ↑BP consider anticholinergic.

8. Smart pumps or two vasopressors may have advantage

9. Women with PET require less – start cautiously

10. Women with cardiac disease should be assessed individually

Anaesthesia 2018, 73,71-92

Norepinephrine Advantages

• ↓maternal bradycardia with ↑cardiac output compared to phenylephrine

• Diluted concentration can be used peripherally as an infusion or IV bolus (5mcg/ml)

• Equipotency to phenylephrine (Ngan Kee study)• Random allocation, graded dose response study

• 180 healthy patients

• Spinal anaesthesia for elective CS

• Estimated equipotency: 100mcg phenylephrine = 8mcg norepinephrine (95% CI, 6 to 10mcg)

Ngan Kee Anaesth Analg 2018; Ngan Kee Anesthesiology 2017

Norepinephrine safety concerns

Potential subcutaneous tissue ischemia with inadvertent extravasation

• High concentration epinephrine in recipient vein and adjacent blood vessels

• Marked vasoconstriction and increased vascular permeability

Significant decrease in peripheral tissue oxygenation

SOAP 2018Fred Hehre Lecture

12 May 2018

“Like sending a man to do a boys work”

Professor Robert Dyer

Plan

• Labour Analgesia

➢ Opiate analgesia

➢ Epidural analgesia

➢ NRFit

➢ Enhanced recovery

• Managing complications and emergencies

➢ Airways

➢ Hypotension and spinal anaesthesia

➢ Haemorrhage: fibrinogen and tranexamic acid

Haemorrhage: Fibrinogen in Pregnancy

Non-pregnant

First trimester

Second trimester

Third trimester

Fibrinogen (plasma)

g/L

2.3-5 2.4-5.1 2.9-5.4 3.7-6.2

Fibrinogen < 2 g/l is an early predictor for severe

PPH

Abbassi-Ghanavati Obstet Gynecol. 2009 Charbit B J Thromb Haemost 2007, de Lloyd IJOA 2011,

Lilley OAA Abst. 2013

Bedside testing: Coagulation

• Thromboelastography• TEG

• Thromboelastometry• ROTEM

• Fibtem

Fibrinogen as treatment

Aim to keep Fibrinogen > 2.0 g/L

Fibrinogen content(g/L)

FFP 1.6-3.6

Cryoprecipitate 3.5-30.0

Fibrinogen concentrate

• 20,060 women• Recruitment 2010-2016• 193 hospitals• 23 countries

• Age ≥ 16 • Clinical diagnosis of postpartum haemorrhage

• Blood loss > 500 ml vaginal delivery or > 1000ml after CS

• Allocated to 1g tranexamic acid or placebo• A second dose could be given if bleeding continued for 30

minutes or restarted within 24 hours

Lancet 2017 389

Effect of tranexamic acid on maternal death

Tranexamic acid group(n=10036)

Placebo group(N = is 9985)

RR (95% CI) p value(two-sided)

Bleeding 155 (1.5%) 191 (1.9%) 0.81 (0.65-1.00) 0.045

Pulmonary embolism 10 (0.1%) 11 (0.1%) 0.90 (0.38-2.13) 0.82

Organ failure 25 (0.3%) 18 (0.2%) 1.38 (0.75-2.53) 0.29

Sepsis 15 (0.2%) 8 (0.1%) 1.87 (0.79-4.40) 0.15

Eclampsia 2 (0.02%) 8 (0.1%) 0.25 (0.05-1.17) 0.057

Other 20 (0.2%) 20 (0.2%) 0.99 (0.54-1.85) 0.99

Any cause of death 227 (2.3%) 256 (2.6%) 0.88 (0.74-1.05) 0.16

Timing of tranexamic acid

Have readily available checklists

Plan

• Labour Analgesia

➢ Opiate analgesia

➢ Epidural analgesia

➢ NRFit

➢ Enhanced recovery

• Managing complications and emergencies

➢ Airways

➢ Hypotension and spinal anaesthesia

➢ Haemorrhage: fibrinogen and tranexamic acid