anesthetic and analgesic methods used for ob anesthesia new innovations joseph e pellegrini, phd,...
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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
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
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
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
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
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
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
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)
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.
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.
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.
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)
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 2009
Post-partum PONV Incidence
05
101520253035404550
Promethazine GroupPlacebo Group
*
* *Sig p< .05
Perc
en
tag
e(%
)
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 2009
VNRS Scores For Nausea
0123456789
1011
Promethazine GroupPlacebo Group
*
* *Sig p < .05
0-1
0 V
NR
S (mean
SD
)
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 2009
Incidence of Postpartum Pruritis
0102030405060708090
100
**
Perc
en
tag
e(%)
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 2009
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
)
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. 2009.
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
)
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. 2009.
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
Questions?Pellegrini@son.umaryland.edu
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