Intrathecal morphine in anesthesia for cesarean delivery: doseresponse relationship for combinations

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Intrathecal morphine in anesthesia for cesarean
delivery dose-response relationship for
combinations of low-dose intrathecal morphine and
spinal bupivacaine Journal of
Clinical Anesthesia (2008) 20, 180185

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Introduction

• Intrathecal morphine (ITM) for CS excellent
  perioperative and postoperative analgesia
• side effects of morphine nausea, vomiting,
  pruritus, and late respiratory depression
• reducing the dose of ITM, reducing SE
• most dose-response studies more than 10 mg of
  bupivacaine combined with morphine prolong the
  time to postoperative first analgesic requirement

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Introduction

• combined low-dose ITM and low-dose spinal
  bupivacaine for cesarean delivery
• IV PCA morphine requirements to evaluate
  analgesia effect
• severity of side effects

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Materials and methods

• prospective, randomized, double-blinded study
• 100 ASA physical status I and II term parturients
  scheduled for CS
• Exclusion criteria patient refusal,
  contraindication to spinal anesthesia, emergency
  cesarean delivery, preeclampsia/eclampsia,
  allergy to drugs used in the protocol

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Materials and methods

• 5 groups 7.5 mg heavy bupivacaine via
  intrathecal injection. Groups 2, 3, 4, and 5
  received 0.1, 0.2, 0.3, and 0.4 mg ITM,
  respectively. Group 1 (control group) received no
  ITM
• Routine monitoring with electrocardiography,
  peripheral oxygen saturation (SpO2), and
  noninvasive arterial pressure (BP)
• 1000 mL Ringer's lactate

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Materials and methods

• 27-gauge Quincke spinal needle was inserted into
  the L3-4. 7.5 mg of 0.5 heavy bupivacaine was
  injected in combination with the assigned
  morphine dose
• The drugs were combined in saline, and 2 mL total
  volume was administered
• Ephedrine, 5 to 10 mg IV, and Ringer's lactate
  solution -- SBP higher than 100 mmHg.
• After delivery, oxytocin 15 IU/L was added to the
  IV fluids

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Materials and methods

• Heart rate, BP, SpO2, side effects monitor
  intraoperatively and at four hour intervals
  throughout the first 24 hours postoperatively
• Nausea and pruritus 0 none, 1 mild
  (requiring no treatment), 2 moderate
  (responsive to treatment), and 3 severe
  (unresponsive to treatment)
• Postoperative vomiting 0 none, 1 one to two
  episodes, 2 3 to 4 episodes, and 3 more than
  4 episodes

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Materials and methods

• highest level of sensory block
• maximum motor block (0 no motor impairment, 1
  unable to lift a straight leg for 5 seconds, 2
  unable to flex the knee, and 3 unable to move
  the ankle joint)
• Apgar scores for the babies
• interval from the end of the surgery to the first
  requirement for analgesia
• Before surgery, patients were instructed in the
  use of the visual analog scale (VAS 0-10)

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Materials and methods

• VAS scores were recorded at four hour intervals
  throughout the first 24 hours postoperatively
• IV Diclofenac 75 mg for VAS scores gt 3
• diphenhydramine, 25 mg, for pruritus
• Metoclopramide 10 mg, for nausea and vomiting
• Total PCA morphine consumption for the first 24
  hours

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Results

• Five patients were excluded conversion to
  general anesthesia (two patients), PCA machine
  problems (two patients), and missing records (one
  patient)

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Results
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Results
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Results
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Results

• no differences between the mean postoperative
  supplemental analgesic requirement in the control
  group and the corresponding values in the
  treatment groups
• Intraoperative and postoperative hemodynamic
  variables remained stable in all 5 groups

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Results
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Results

• no significant differences among the 5 groups'
  mean postoperative diphenhydramine or mean
  metoclopramide requirements
• None of the patients developed clinical evidence
  of severe respiratory depression

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Discussion

• Combination of ITM and hyperbaric bupivacaine is
  a simple and effective method for controlling
  postoperative pain in patients undergoing
  cesarean delivery
• Some authors have reported problems with side
  effects
• Studies have focused on determining the lowest
  effective ITM dose

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Discussion

• Abboud et al 0.25 mg or 0.1 mg of ITM, excellent
  analgesia of long duration (27.7 4.0 and 18.6
  0.9 hrs, respectively)
• Abouleish et al 0.2 mg of ITM, 27 7.3 hours as
  the average time to first requirement for
  postoperative opioids
• Milner et al compared 0.1 mg of ITM versus 0.2
  mg of ITM, no statistical difference between
  these groups with respect to time to first
  analgesic requirement

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Discussion
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Discussion

• Swart et al 0.1 mg of ITM or intrathecal saline,
  PCA-morphine consumption at 24 hours was lower in
  the 0.1-mg ITM group
• Palmer et al received 0 mg of ITM (control
  group) used significantly more PCA-morphine than
  6 of the other groups, which received 0.075, 0.1,
  0.2, 0.3, 0.4, or 0.5 mg of ITM
• ITM provides substantial analgesia, even at very
  low doses

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Discussion

• In the setting of spinal anesthesia,
  postoperative nausea and vomiting is usually
  caused by hypotension. Aggravated by uterine
  manipulation and peritoneal closure
• incidence of nausea and vomiting after ITM may be
  related to the dose of morphine

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Discussion

• Abboud et al 0 mg, 0.25 mg, and 0.1 mg of ITM,
  nausea and vomiting occurred at the same
  frequency in both ITM groups
• Abouleish et al 0.2 mg of ITM, intraoperative
  vomiting significantly less frequently than the
  control group
• Palmer et al compared the effects of 8 different
  doses of ITM (minimum, 0.025 mg maximum, 0.5
  mg), no relationship between postoperative
  nausea/vomiting and ITM dose

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Discussion

• Pruritus is a common and troublesome side effect
  of intrathecal opioid administration after
  cesarean delivery
• Opioid dose is very important relative to this
  side effect
• Pruritus incidence rates of 60 to 65 have been
  reported after administration of 0.1 to 0.2 mg of
  ITM

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Discussion

• Palmer et al In their 8 groups of cesarean
  delivery patients, pruritus severity increased in
  direct proportion to ITM dose
• In the study, there was a trend toward higher
  postoperative mean diphenhydramine requirements
  in the treatment groups, but there were no
  significant differences
• small sample size affected this result

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Discussion

• Delayed respiratory depression is the most feared
  side effect of intraspinal opioids
• spread of morphine in the subarachnoid space to
  the cisterns and then to the pons
• Clinical reports suggest that delayed respiratory
  depression is associated with intrathecal
  injection of morphine at doses more than 1.0 mg

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Discussion

• no evidence of respiratory depression after
  various low doses (range, 0-0.4 mg) of ITM
• closely monitored in the first 24 hours after
  surgery

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Conclusion

• low-dose hyperbaric bupivacaine combined low
  doses of ITM for cesarean delivery excellent
  perioperative and postoperative analgesia
• 0.1 mg of ITM produces postoperative analgesia of
  similar quality and duration to that produced by
  0.2, 0.3, or 0.4 mg ITM but with lower occurrence
  of pruritus

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• Thank you !!