03 warwick ngan kee

Regional Anaesthesia for Caesarean SectionWarwick D. Ngan KeeDept of Anaesthesia & Intensive CareThe Chinese University of Hong Kong

• Spinal Drugs Fluids Blood Pressure

• CSE Dose

• Epidural Topup

OUTLINE:

Local Anaesthetic

Bupivacaine

Bupivacaine is the local anaesthetic of choice

Hyperbaric vs Plain:• Faster onset

• Less conversion to GA

Hyperbaric vs Plain:• Faster onset

• Less conversion to GA

• Less variability of block

Hyperbaric local anaesthetic more reliable

Local Anaesthetic

Bupivacaine

Additives+

• Opioids • Adrenaline• Clonidine• Neostigmine• Ketamine

Possible advantages:

1. Decrease side effects

2. Increase efficacy

Adding adjunct agents

Possible disadvantages: 1. Drug error

2. Breach of sterility

3. Incompatibility

4. Cost

5. Safety (often “off-label”)

Adding adjunct agents

• Opioids • Adrenaline• Clonidine• Neostigmine• Ketamine

Only add an opioid

Local Anaesthetic

Bupivacaine Fentanyl

Lipophilic Opioid+

Bupivacaine Spinal

Added Fentanyl 0 - 50 µg

0 2.5 5 6.25 12.5 25 37 50

Fentanyl Dose (µg)

IntraopOpioid(%)

67%

50%

25%

0% 0% 0% 0% 0%

Intraoperative Opioid Supplementation

Hunt et al. Anesthesiology 1989;71:535-40.

Nausea and Vomiting?

Elective Spinal Caesarean (n=30)

Hyperbaric Bupivacaine 12 mg

• FENTANYL: Less intraoperative pain • FENTANYL: Less intraoperative nausea

Manullang et al. Anesth Analg 2000;90:1162-6.

IV Ondansetron 4 mg

IT Fentanyl15 µg

Adding an opioid improves patient comfort

Morphine• 100 - 200 µg

• Preservative-free

• Postop analgesia

Morpheus


• CSE Dose

• Epidural Topup

OUTLINE:

Intravenous fluidsMany Uncertainties

Colloidvs

Crystalloid?

Prehydration vs

Cohydration?

Prehydration

Rapid IV fluid infusion started before spinal injection

(Preload)

Cohydration(Coload)

Rapid IV fluid infusion started after spinal injection

Crystalloid

Prehydration Cohydration

Colloid

IV Fluid: Type and Timing

Crystalloid

Prehydration Cohydration

Colloid

- +

+ +

IV Fluid: Type and Timing

Colloid Prehydration:

• Cost.• Effects on coagulation.• Fluid overload. • Haemodilution.• Allergic reactions.

D I S A D V A N T A G E S

Recommendation:• Crystalloid: cohydration• Colloid: prehydration or cohydration• Don't rely on IV fluids • Don't delay for IV fluids


• CSE Dose

• Epidural Topup

OUTLINE:

Phenylephrine

A L P H A A G O N I S T SA L P H A A G O N I S T S

Phenylephrine


• Phenylephrine is more effective

Why use phenylephrine?

PhenylephrineEphedrine

carbon

hydrogen

oxygen

nitrogen

Phenylephrine


• Phenylephrine is more effective

Why use phenylephrine?

• Ephedrine causes fetal acidosis

Lee A, Ngan Kee WD, Gin T. Anesth Analg 2002;94 920-6.

Figure 1. Meta-analysis of trials - effect on umbilical arterial pH

Weighted mean difference (umbilical cord arterial blood pH)

-0.10 -0.05 0.00 0.05 0.10

Alahuhta

Hall

LaPorta

Moran

Pierce

Thomas

Overall effect

Favours ephedrine Favours phenylephrine

Ephedrine depresses fetal pH and BE

00.20.40.60.81.01.21.41.61.82.0

Ephedrine Phenylephrine

1.13

0.17 *

* P < 0.0001

Umbilical Venous : Maternal Arterial (Median values)

Ngan Kee WD Anesthesiology 2009; 111:506-12

Ephedrine crosses the placenta more

Phenylephrine

• Preparation

How to use phenylephrine?

• Timing

• Method of Giving

10 mg / 1ml 100 ml

+ = 100 µg/ml

Dilute carefully…..

Preparation....

Prevention versus Treatment

Timing....

Most effective management: •Start administration immediately after intrathecal injection

• Both effective• Intermittent bolus simple• Infusion convenient

Infusion versus Boluses

Method of Giving....

Recommendation:

• Bolus dose: 50-100 µg (0.5-1ml)• Begin immediately after IT injection• Measure BP Q1min• Further boluses when BP start to decrease

Bolus technique:

Recommendation:Infusion technique:

• Syringe pump• Start 50 µg/min immediately after induction• Measure BP Q1min• Increase rate if BP falls• Decrease/stop if BP increases

Recommendation:What about bradycardia?

• Associated with cardiac output • Tolerate to 50-60 bpm

• BP low: IVF, ephedrine, atropine/glycopyrrolate*

• BP high/normal: stop and wait!

* Beware hypertension with anticholinergics!

• Preeclampsia• Fetal compromise

• Few studies • Less vasopressor needed

Recommendation:What about high risk cases?

• Use less aggressive dosing


• CSE Dose

• Epidural Topup

OUTLINE:

Dose required for adequate spinal block

Single shot spinal

Single shot spinal


CSE


0

20

40

60

80

100

StandardLow Dose

Hypotension(%)

73%

14%

P < 0.001

Incidence of Hypotension

Teoh et al. Int J Obstet Anesth 2006;15:273-8

**


• CSE Dose

• Epidural Topup

OUTLINE:

Hillyard et al. Br J Anaesth 2011;107:668-78

2008-2009• 93,000 Emerg C-sections• 22% Epidural Anaesthesia

Labour Epidural Topups

Assessment of Urgency

Assessment of Epidural Function

Type of Anaesthetic?

GA Regional

(With informed consent)

Epidural Topup

OK

De Novo Spinal(or CSE)

Not OK

Assessment of Epidural Function

• How is pain control?

• How much local anaesthetic?

• What is block height?

• How frequent interventions?

Epidural Topup….

….or De Novo Spinal?

Assessing Epidural:

Epidural Topup….

….What Drug?

BupivacaineLevobupivacaineRopivacaine

Lidocaine(+ epinephrine)

Emergency TOPUPS

• Speed of onset

• Safety

• Often given under time pressure

• Large dose, given rapidly

CONSIDERATIONS

• If the quality of epidural block is paramount, then 0.75% ropivacaine is suggested.

• If the speed of onset is important, then a lidocaine and epinephrine solution, with or without fentanyl, appears optimal

Complications of Extension of Epidural Block

Complications of Extension of Epidural Block

Regan KL, O'Sullivan G. Anaesthesia 2008;63:136-42

8

14

6

2

1

12

F A I L E D B L O C K

F A I L E D B L O C KAssessment & Discussion

GA Regional

(With informed consent)


0.16%

11.1%

Furst SR, Reisner LS. J Clin Anesthesia 1995;7:71-4

Spinal After Epidural: Risk of High Block

F A I L E D B L O C KAssessment & Discussion

GA Regional


Reduce Dose

K E Y P O I N T S

Regional Anaesthesia for Caesarean Section

K E Y P O I N T S

Spinal Anaesthesia• Hyperbaric local anaesthetic

• + Fentanyl / Sufentanil

• ± Morphine


Intravenous Fluids• Crystalloid cohydration

• Colloid prehydration or cohydration

• No need to delay for fluids

K E Y P O I N T S


Vasopressors• Avoid large doses of ephedrine before delivery

• Phenylephrine preferred

• Bolus or infusion

• Bradycardia: stop and wait.

K E Y P O I N T S


Combined Spinal Epidural (CSE)• Good for reducing dose

• Better haemodynamic stability

• Useful for prolonged surgery

K E Y P O I N T S


Epidural Topup for C-Section• 2% Lidocaine + Adrenaline ± Bicarbonate

• 0.75% Ropivacaine

• Spinal after epidural: reduce dose

K E Y P O I N T S


Regional Anaesthesia for Caesarean SectionWarwick D. Ngan KeeDept of Anaesthesia & Intensive CareThe Chinese University of Hong Kong

03 warwick ngan kee

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