Warwick D. Ngan Kee Dept of Anaesthesia & Intensive Care

The Chinese University of Hong Kong

Regional Anaesthesia for

Caesarean Section "The Best Recipe"

What I will not do…. • Magic recipes

• One shoe to fit all

What I will do…. • Discuss selected

controversial issues

• Practical recommendations

• Preassessment

• Premedication

• Consent

• Monitoring

• Vascular access

• 1-2-3

• Postop analgesia

BASICS

OUTLINE • Techniques

• Drug Choice

• Fluids

• Vasopressors

• Oxygen

• Drug Dose

Epidural Spinal CSE

Time

Simplicity

Drug Dose

Block Quality

Hypotension

Duration

Recovery

O P T I O N S

OUTLINE • Techniques

• Drug Choice

Local

Anaesthetic

Bupivacaine

Sia et al. (Cochrane Review)

Onset Speed (time to T5 block)

Conversion to General Anaesthesia

Sia et al. (Cochrane Review)

Coefficient of variation: 17.7% 21.9%

Block Height

Khaw et. Anesth Analg 2002;94:680-5.

• Opioids

• Adrenaline

• Clonidine

• Neostigmine

• Ketamine

Additives

Possible advantages:

1. Decrease side effects 2. Increase efficacy

Adding adjunct agents

Possible Disadvantages:

Adding adjunct agents

1. Drug error

2. Breach of sterility 3. Incompatibility

4. Cost

5. Safety (often “off-label”)

Elective Spinal Caesarean (n=56)

Height-adjusted IT Bupivacaine

• Quality of Block

• Intraoperative Analgesic Requirement

Added Fentanyl 0-50 µg

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

0

20

40

60

80

100

1 2 3 4 5 6 7 80 2.5 5 6.25 12.5 25 37 50

Fentanyl Dose (µg)

Intraop

Opioid

(%)

67%

50%

25%

0% 0% 0% 0% 0%

Intraoperative Opioid Supplementation

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

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 Fentanyl

15 µg

OUTLINE • Techniques

• Drug Choice

• Drug Dose

Dose required for adequate spinal block

Single shot spinal

Low Dose

(≤ 8 mg bupivacaine)

Conventional Dose

(> 8 mg bupivacaine) VS

Arzola and Wieczorek. Br J Anaesth 2011;107:308-18

HYPOTENSION: Low Dose vs Conventional Dose

Arzola and Wieczorek. Br J Anaesth 2011;107:308-18

NAUSEA/VOMITING: Low Dose vs Conventional Dose

Arzola and Wieczorek. Br J Anaesth 2011;107:308-18

SUPPLEMENTATION: Low Dose vs Conventional Dose

“Low dose bupivacaine….compromises anaesthetic

efficacy…despite the benefit of lower maternal side

effects”

“Lower anaesthetic doses cannot be recommended

unless an epidural catheter is in place (CSE)…”

Recommendation: • Use smallest dose of LA for circumstances

• Add opioid (fentanyl/sufentanil)

• CSE: useful for high-risk or long surgery

OUTLINE • Techniques

• Drug Choice

• Fluids

• Drug Dose

Intravenous fluids

• Why?

• What?

• When?

• How much?

• How fast?

Uncertainties:

Crystalloid

Prehydration Cohydration

Colloid

- + + +

IV Fluid: Type and Timing

( )

CLINICAL INVESTIGATIONS

Anesthesiology

1999;91 1571-6

© 1999 American Society of Anesthesiologists, Inc.

Lippincott Williams & Wilkins, Inc

Effects of Crystalloid and Colloid Preload on Blood

Volume in the Parturient Undergoing Spinal

Anesthesia for Elective Cesarean section Hiroshi Ueyama, M.D.,* Yan-Ling He, Ph.D.,† Hironobu Tanigami, M.D.,* Takashi Mashimo, M.D.,‡ Ikuto

Yoshiya, M.D.

Elective Caesareans (n=36)

Lactated

Ringers

1.5 L

HES

0.5 L

HES

1.0 L

Ueyama et al. Anesthesiology 1999;91:1571-6.

• Hypotension

• Blood volume & cardiac output

Hyp

ote

nsio

n in

cid

en

ce (%

)

0

0.25

0.5

0.75

1.0

1.25

1.5

LR 1.5L HES 0.5L HES 1.0L

Blood volume increase

0

10

20

30

40

50

60

70

80

90

100 Hypotension incidence B

loo

d V

olu

me in

cre

ase (

L)

Adapted from Ueyama H et al. Anesthesiology 1999; 91:1561-6

• Cost.

• Effects on coagulation.

• Fluid overload.

• Hemodilution.

• Allergic reactions.

Colloid Prehydration:

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

OUTLINE • Techniques

• Drug Choice

• Fluids

• Vasopressors

• Drug Dose

Phenylephrine

0

10

20

30

40

50

60

70

80

90

100

Ephedrine Phenylephrine Other

%

95.2%

0.4% 4.5%

42% 51%

6%

1999

2007

Vasopressors at Caesarean

section

• 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

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Ephedrine Phenylephrine

1.13

0.17

Placental Transfer of Ephedrine and Phenylephrine

*

* P < 0.0001

Umbilical Venous : Maternal Arterial (Median values)

Ngan Kee WD Anesthesiology 2009; 111:506-12

0

1

2

3

4

5

Ephedrine Phenylephrine

UA Lactate

50

55

60

65

Ephedrine Phenylephrine

UA Glucose

0

200

400

600

800

Ephedrine Phenylephrine

UA Adrenaline

0

1000

2000

3000

4000

5000

6000

Ephedrine Phenylephrine

UA Noradrenaline

pg/m

l

pg/m

l m

mo

l/l

mg/d

l

(all P < 0.05)

Ngan Kee WD Anesthesiology 2009; 111:506-12

Keeping blood pressure near baseline gives better

maternal outcome

Optimal Target Blood Pressure?

Elective Spinal Caesareans (n=75)

Crystalloid Prehydration

Phenylephrine Infusion

Three Target Blood Pressures

80% of

Baseline

90% of

Baseline

100% of

Baseline

0

20

40

60

80

100

Gp80 Gp90 Gp100

Incidence of Nausea/Vomiting

Ngan Kee et al. Br J Anaesth 2004;92:469-74

40%

16% 4%

How best to use phenylephrine?

• Timing of administration

• Method of administration

• Preparation

Dilute carefully…..

Prevention versus Treatment

Timing....

Most effective management:

• Start administration immediately after

intrathecal injection

Method….

• Both effective

• Intermittent bolus simple

• Infusion convenient

• Infusion less work

Infusion versus Boluses

INFUSION:

• Less hypotension

• More hypertension

• Less nausea/vomiting

• Fewer physician interventions

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:

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

Bolus technique:

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 • Use less aggressive dosing

Recommendation: What about high risk cases?

OUTLINE • Techniques

• Drug Choice

• Fluids

• Vasopressors

• Oxygen

• Drug Dose

• Can it do any harm?

• Should I (not) give oxygen?

O X Y G E N

• Does it do any good?

• Increase fetal oxygenation

• Reduce effects of hypoventilation

• Protection during prolonged U-D time

• Reduce effects of hypotension

• Safety in conversion to GA • Decrease nausea & vomiting

• Decrease wound infection

POTENTIAL B E N E F I T S

Elective C-sections (n=204)

Khaw, Ngan Kee et al. Br J Anaesth 2004; 92: 518-22

60% O2

40% O2

Air

• Cord gases & O2 content.

• Subanalysis for U-D time >180 s

High flow venturi facemask

21% 40%

UV PO2

(mmHg) 28 29

0 20 40 60 80

100

21% 40%

UV Hb

Saturation

(%) 63 67

0

5

10

15

20

21% 40%

UV O2

Content

(mL/dL) 12.9 13.4

Khaw KS, Ngan Kee WD et al. Br J Anaesth 2004; 92: 518-22.

0

10

20

30

40

60%

32 * P = 0.003

*

60%

70 ** P = 0.015

**

60%

14.4 *** P = 0.015

***

• Can it do any harm?

• Should I (not) give oxygen?

O X Y G E N

• Does it do any good?

Oxygen free radical generation

“In healthy parturients undergoing elective Caesarean section, it

would appear that additional oxygen is unnecessary.”

“It seems reasonable, based on current knowledge, to continue to

give supplementary oxygen to mothers undergoing

emergency/unplanned Caesarean section…”

Summary • Use spinal or CSE

• Heavy bupivacaine + opioid

• Dose: empirical

(low dose fentanyl 10-15µg)

Summary

• Crystalloid: cohydration

• Colloid: pre- or cohydration

• Don't rely on fluids

• Don't delay for fluids

Summary • Phenylephrine or metaraminol

• Start early

• Keep BP near baseline

• Care with anticholinergics

Summary • Routine O2 unnecessary

• Be guided by pulse oximeter

Warwick D. Ngan Kee Dept of Anaesthesia & Intensive Care

The Chinese University of Hong Kong

Regional Anaesthesia for

Caesarean Section "The Best Recipe"