anesthetic and analgesic methods used for ob anesthesia new innovations joseph e pellegrini, phd,...

Anesthetic and Analgesic Methods Used for OB Anesthesia

New Innovations

Joseph E Pellegrini, PhD, CRNAAssociate Professor

Deputy Program Director

University of Maryland Nurse Anesthesia Program

Obstetrical Anesthesia Evolution taking place

Use of CLE from 16% in 1985 to > 50% in 2000 Practice changes

Introduction of new drugs, techniques, and delivery apparatus

Consumerism Litigation

Increased demands on Anesthesia Providers 24/7 coverage

Increased research in OB anesthesia arena Promoted changes in Anesthesia Dept. guidelines

Goals of Laboring Analgesia Principle Goal

Delivery of a healthy neonate Expelling the fetus & placenta

Three distinct stages of Labor Each stage has different analgesic requirements

Pain of Parturition

Pain Centers during labor progression

Initiation of Epidural Analgesia Continue to have controversy as to when to

initiate epidural analgesia Some advocate waiting until 4 cm dilatation

whereas others initiate at request Early initiation associated with prolonged stages

of labor Early initiation associated with increased

dystocia, instrumental and operative delivery rates Recent study dispute these claims

Early

Early

Late

Late

Outline New Innovations for Laboring Analgesia

CSE Technique Patient Controlled Epidural Analgesia

With or without a basal infusion rate With or without predetermined timed boluses

New Innovations for Cesarean Section Opioids administered for postoperative analgesia

DepoDur for postoperative analgesia Side effect prophylaxis

Control of opioid induced side effects

The CSE Technique Viewed as most significant advancement in OB anesthesia in

the last decade CSE - Usually performed using a needle-thru-needle

technique

Intrathecal opioids very effective in controlling 1st stage labor pain Fentanyl 10-25 ug or Sufentanil 5-7.5 ug with/without morphine 0.1-0.25 mg

and/or bupivacaine 2.5 mg Addition of bupivacaine efficacy in question – typically not efficacious for

2nd stage labor pain Need adequate amounts of local anesthetics to effectively block the

pain for 2nd stage labor pain Routinely administered via CLE

The CSE Technique

CSE technique often given in combination with an epidural infusion Traditional Method –

Bolus before infusion Traditional Admixtures

.125% - .25% Bupivacaine with/without 50-100 mcg fentanyl .2% Ropivacaine with/without 50-100 mcg fentanyl

CLE infusion (continuous infusion) 0.1-0.125% Bupivacaine with or without 1-2 mcg/ml fentanyl at 8-15 ml/hr 0.125-0.2 Ropivacaine with or without 1-2 mcg/ml fentanyl at 8-15 ml/hr

Alternative Method - Patient Controlled Epidural Analgesia (PCEA)

Becoming more popular in OB anesthesia practices Often administered immediately following placement of intrathecal opioids

with small basal rates and set maximum hourly dose Advantages

Less variability in the peak plasma concentration of drug Faster onset of analgesia Titrate able Greater pain control and Satisfaction scores noted when compared to

traditional continuous infusion rates

CSE for Cesarean Delivery CSE use during c-section associated

with higher sensory blockade Conflicting results

Both studies - CSE performed without injection or catheter placed into epidural space

Anecdotal information – no differences noted in my own clinical practice when epidural catheter placed Noted difference if test dose

administered following IT injection Epidural often used for

placement of Morphine & 10 ug fentanyl administered via IT injection with 10-12 mg hyperbaric bupivacaine

Possible difference is lateral orientation of spinal needle during injection as opposed to cephalad orientation

Patient Controlled Epidural Analgesia PCEA accords laboring women autonomy in pain

relief for labor and has been shown to very effective and desirable

Wide variety of dosing options Often dependent whether or not initial bolus dose

administered following test dose Greater degree of maternal satisfaction reported

when PCEA compared to conventional continuous infusion

Recipes for PCEAAnesthetic Solution Basal Rate

(ml/hr)

Bolus Dose

(ml)

Lockout interval

(minutes)

Maximum hourly dose (ml)

Bupivacaine 0.125% 4 4 20 20

Bupivacaine 0.125%

+ fentanyl 2 mcg/ml

(if bolus given)

5 3 7 18

Bupivacaine 0.125%

+ fentanyl 2 mcg/ml

(if bolus not given)

6-8 3 7 25

Bupivacaine 0.25% 0 3 10 20

Bupivacaine 0.1%

+ fentanyl 2 mcg/ml

10 5 10 26

Ropivacaine 0.125% 6 4 10 24

Ropivacaine 0.125%

+ fentanyl 2 mcg/ml

5 3 10 20

From Gambling DR, McMorland GH, Yu P, Laszlo C. Comparison of patient-controlled epidural analgesia and conventional intermittent “top-up” injections during labor. Anesth Analg 1990: 70: 256-61

PCEA versus Conventional therapy

PCEA Traditionally PCEA is administered with or

without a basal infusion rate Some clinicians report that basal infusion rates

not required Omitting a basal infusion rate reduces analgesic

consumption but conflicting results regarding effect on stage 2 labor and satisfaction Recently conducted study analyzing effect on maternal

hemodynamics, fetal and neonatal hemodynamics, length of stage 2 labor, effect on mode of delivery and maternal motor function and overall maternal analgesic satisfaction

Webster A, Lawson S, Nezat G, Pellegrini JE. Comparison of outcomes between groups of parturients administered PCEA laboring analgesia with and without a continuous basal infusion. 2009 Unpublished Data

Primary questions? What are the differences in relation to overall analgesic requirements and

maternal, fetal and neonatal outcomes between groups of parturients administered a PCEA for laboring analgesia with or without a background basal epidural infusion

Methods 100 subjects enrolled CSE technique used – all parturients administered 10 mcg intrathecal

fentanyl Parturients consented and randomized to receive PCEA laboring analgesia

with or without a background basal infusion rate One group received PCEA alone using 0.2% ropivacaine 5 ml boluses with a 15

min lockout (total of 20 ml/hr) One group received PCEA using 0.2% ropivacaine 5 ml boluses with a 15 min

lockout in combination with a background infusion of 0.2% ropivacaine of 5-10 ml/hr (maximal total set at 30 ml/hr)

No differences in demographic variables No differences in VNRS scores for pain at any interval

measurement Measured q 5 minutes following initiation for 30 minutes then q 1

hour thereafter until delivery No differences in mode of delivery

SVD (72% in PCEA group;80% in PCEA + CLE group) Instrument assisted (5% in PCEA group; 4% in PCEA + CLE group) Cesarean Section (23% in PCEA group; 16% in PCEA + CLE group)

No differences in analgesic satisfaction scores Both groups reported satisfaction or complete satisfaction with

laboring analgesia



Time from Epidural Initiation to Top-off Dose

050

100150200250300350400450500550

PCEAPCEA + CLE

Tim

e (

min

ute

s)

(Me

an

S

D)

*

*Sig p < .05

Top off dose #1 -31% of PCEA population23% of PCEA + CLE population

Top off dose #2 -9% of PCEA population11% of PCEA + CLE population

Median Number of PCEA Attempts

PCEA PCEA + CLE0123456789

101112

PCEAPCEA + CLE

*

*Sig p < .05

Numb

er of

Attem

pts


Length of Stage 2 Labor

PCEA PCEA + CLE0

10

20

30

40

50

60

70

80PCEAPCEA + CLE

*Sig p < .05

*

Len

gth

(m

inu

tes)

(Me

an

S

D)

Total Amount of Ropivacaine

PCEA PCEA + CLE0

102030405060708090

100110120

PCEAPCEA + CLE

*

To

tal

Am

ou

nt

(ml)

(Me

an

S

D) *Sig P < .05


Conclusions Preliminary Data

No differences in level of analgesia afforded PCEA alone supports previous studies regarding analgesic consumption Noted shortened stage 2 labor in PCEA alone group but no adverse

effects on mode of delivery Both are viable options but data reported is preliminary

Despite findings many practitioners prefer inclusion of basal rate with PCEA Novel approach to basal rate recently investigated

Recent investigation analyzing differences between groups of parturients that received either traditional PCEA + basal continuous infusion or PCEA with automated mandatory boluses

Oxytocin at Cesarean Section Oxytocin is routinely administered following delivery

Oxytocin can be administered immediately after delivery of the shoulders, before or after delivery of the placenta If administered before delivery of placenta decreased blood loss has been

observed Controversy exists concerning infusion versus bolus or combination

Infusion traditionally initiated at 200-300 mU/min (20 U/L @ 10 ml/min or 30U/L @ 7.5 ml/min) for several minutes until the uterus firmly contracted and no active bleeding noted Effect of oxytocin dependent on number of oxytocin receptors

Pregnancy causes a 180 fold increase in concentration of oxytocin receptors with the greatest increase occuring just before the onset of labor

Administration of rapid IV bolus may cause significant hypotension & cardiovascular collapse Some practitioners advocate administration of a single IV bolus of 2-5 units of

oxytocin at time of delivery (most often in addition to infusion) Studies have shown that administration of a 10 unit bolus can result in complete

cardiovascular collapse

Bottom Line:

Be vary cautious in administration of oxytocin bolus especially when faced with parturient with low MAP & Maternal pulse – can result in complete cardiovascular collapse

Cesarean Section – Postoperative Analgesia Spinal Anesthesia

70% of all elective cesarean sections are performed using SAB Approximately 90% receive intrathecal morphine for postoperative analgesia

Dose ranges from 0.10 – 0.30 mg Analgesia efficacy from 14-24 hours Moderate to high side effect profile - some studies indicating higher profile when ITN used as

compared to when epidural morphine is administered Epidural Anesthesia

Routinely used when epidural analgesia is used for labor Estimated that over 90% received PF Morphine Sulfate for postoperative analgesia

Dosing regimen administered (2-5 mg) Duration of action 16-24 hours Side effect profile moderate to high

Studies using conventional PF Morphine at increased doses fail to yield longer durations of action

Recently investigations have been done using extended release liposome injection morphine (DepoDur) Formulated in an attempt to increase the duration of analgesic action of epidural

morphine

Depo-Dur DepoDur (morphine sulfate extended-release liposome injection) is a sterile suspension

of multivesicular liposomes using proprietary DepoFoam® formulation technology containing morphine sulfate, intended for epidural administration. DepoFoam is a drug delivery system that encapsulates the morphine sulfate and allows it to

be released slowly over time for a period of approximately 48 hours Allows analgesia for approximately twice as long as conventional DuraMorph

Traditionally DuraMorph administered to cesarean section patients in doses ranging from 2-5 mg

Depo-Dur administered to cesarean section patients in doses ranging from 5-15 mg Studies indicate a ceiling dose effect achieved at 10 mg

Recent study analyzed effect between groups of cesarean section patients administered either 10 mg DepoDur or 4 mg DuraMorph Enrolled 70 ASA 1 and 2 cesarean section patients to receive one of the two regimens Analyzed differences in analgesic requirements, pain scores, postop activities and side effects

between the groups

Carvalho B, Roland, LM, Chu LF et al. Single-dose, extended release epidural morphine (DepoDur™) compared to conventional epidural morphine for post-cesarean section pain. Anesth Analg 2007; 105: 176-83.

(At rest)

(With Activity)



DepoDur provided longer latency of analgesia and greater satisfaction Better analgesia 24-48 (but was it clinically significant?)

Both conventional and Extended released morphine solution resulted in moderate to high side effect profiles Side effects reported in the range of 20-60%

for PONV & 40-100% for pruritis Side effects traditionally treated with oral

histamine blockers (questionable efficacy), antiemetics or opioid antagonists (often at the expense of analgesia)

There has been no definitive treatment regimen for treatment of side effects identified to use in post-cesarean section population

What can we give to treat or prevent side effects in the parturient population that has been given

neuraxial morphine sulfate? Recent study analyzed effect of prophylactic IM

promethazine in groups of c-section patients administered intrathecal morphine for SAB

Promethazine Common antiemetic agent used in OB

Possesses strong anticholinergic and antihistamine properties

Two studies noted that when Promethazine administered as antiemetic agent to groups of patients administered epidural/intrathecal morphine noted a significant reduction in PONV and pruritis Both studies used small sample sizes (<20 patients) Not used in OB population Study design not specific to measure pruritis

Study performed to determine if promethazine effective in preventing PONV & pruritis in a cesarean section population administered intrathecal morphine

Litchfield, J, Pronk C, Nezat G, Pellegrini JE. Effect of 25 mg IM promethazine on the incidence and severity of PONV and pruritis in a cesarean section population receiving intrathecal morphine. Accepted AANA J 2008

Enrolled 60 ASA 1 & 2 subjects scheduled for elective cesarean section

All subjects administered SAB with 12 mg bupivacaine, 10 mcg fentanyl and 0.3 mg Dura Morph

Randomized to receive either 25 mg IM promethazine or placebo in vastus lateralis immediately after SAB placed Double blind Placebo Controlled Informed consent

Demographic Variables

Promethazine Placebo

Gravida (range) 1-7 1-7

Parity (range) 0-3 0-4

Ethnicity Caucasian (N) African-American (N) Hispanic (N) Asian (N)

18840

19632

Height (Mean inches ± SD) 64 ± 2.4 64 ± 2.0

Weight (Mean Kg ± SD) 89 ± 17 85 ± 14

Total Surgical Time (Mean min ± SD) 47 ± 18 45 ± 17

Total PACU Stay (Mean min ± SD) 125 ± 42 125 ± 57

Litchfield J, Pronk C, Nezat G, Pellegrini JE. Effect of 25 mg IM promethazine on the incidence and severity of PONV and pruritis in a cesarean section population receiving intrathecal morphine. Accepted AANA J. 2008.

Promethazine Prophylaxis Study Findings No difference in level of pain on injection noted between

groups No complaints of pain on injection reported

Higher incidence in level of sedation noted in placebo group Not Significant

Apgar Scores One Minute

Promethazine group range (7-9) Placebo group range (6-9)

Five Minute Promethazine group range (8-9) Placebo group range (7-9)


Post-partum PONV Incidence

05

101520253035404550

Promethazine GroupPlacebo Group

*

* *Sig p< .05

Perc

en

tag

e(%

)


VNRS Scores For Nausea

0123456789

1011

Promethazine GroupPlacebo Group

*

* *Sig p < .05

0-1

0 V

NR

S (mean

SD

)


Incidence of Postpartum Pruritis

0102030405060708090

100

**

Perc

en

tag

e(%)


VNRS Scores for Itching

PACU Arri

val

PACU 1st

Com

plain

t

War

d Arri

val

War

d 1st

Com

plain

t0

1

2

3

4

5

6

7

8

9Promethazine GroupPlacebo Group

0-10

VN

RS

Sco

re

Nausea Control SatisfactionMedian Satisfaction Scores for Nausea Control

Placebo Promethazine0

1

2

3

4

5PlaceboPromethazine

*

*Sig p < .05

1= Totally Dissatisfied2= Dissatisfied3= Somewhat Satisfied4= Satisfied5= Totally Satisfied

Med

ian

Sco

re

(1-5

Scale

)


Pruritis Control SatisfactionMedian Satisfaction Scores for Prutitis Control

Placebo Promethazine0

1

2

3

4

5PlaceboPromethazine

*

*Sig p < .05

1= Totally Dissatisfied2= Dissatisfied3= Somewhat Satisfied4= Satisfied5= Totally Satisfied

Med

ian

Sco

re

(1-5

Scale

)


Conclusions CSE is suggested method for analgesia in many OB anesthesia practices PCEA reduces analgesic requirements and increases satisfaction in some

studies Basal infusion rates increase length of stage 2 labor but no adverse effects

noted in relation to mode of delivery PCEA with bolus can lead to higher incidence of cesarean section Rapid infusion of oxytocin can result in significant hemodynamic

instability Extended release morphine shown to be safe and effective to use in

cesarean section population Prolonged duration of analgesia

Some concerns over prolonged side effect profile Cannot use epidural catheter concomitantly with local anesthetic

Promethazine is viable option to prevent IT and epidural opioid induced side effects in a cesarean section population

[email protected]

anesthetic and analgesic methods used for ob anesthesia new innovations joseph e pellegrini, phd,...

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