TC02 Obese Women Using It Morphine vs PCA IV Hydromorphone for Post-Cesarean Analgesia



Status:Not yet recruiting
Conditions:Obesity Weight Loss, Post-Surgical Pain, Cardiology, Pulmonary
Therapuetic Areas:Cardiology / Vascular Diseases, Endocrinology, Musculoskeletal, Pulmonary / Respiratory Diseases
Healthy:No
Age Range:18 - 65
Updated:3/16/2019
Start Date:August 2019
End Date:December 2021
Contact:Feyce Peralta, MD
Email:feyce.peralta@northwestern.edu
Phone:312-472-3585

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Randomized Controlled Trial Evaluating the Transcutaneous Carbon Dioxide Measurements in Obese Women Using Intrathecal Morphine Versus Patient-Controlled Intravenous Hydromorphone for Post-Cesarean Analgesia

Cesarean deliveries are the most commonly performed surgery in the United States and account
for 32.9% of all births.8,9 The ASA recommends the use of neuraxial opioids of post-cesarean
analgesia partly because respiratory depression in the obstetric population, as measured by
intermittent respiratory rate and pulse oximetry, is reported to be low (0-1.2%).10,11
Respiratory depression lacks a standard definition,12 but the most sensitive means of
detecting respiratory depression is hypercapnia.1,3 Two recent studies using continuous
hypercapnia (>50mmHg PaCO2) monitoring demonstrated higher rates of respiratory depression
(17.8-37%) in healthy, non-obese women receiving intrathecal opioids for post-cesarean
analgesia.13,14 In addition, supplemental opioids are required in the majority of women
receiving intrathecal morphine and may increase the risk of respiratory depression.11,14
Anesthesiologists debate whether neuraxial opioids or intravenous patient controlled opioid
analgesia (PCA) are the safest practice for postoperative analgesia in obese parturients
following cesarean delivery. The ASA recommendations to employ neuraxial analgesia
post-cesarean delivery does not differentiate between non-obese and obese women who now make
up 30.3% in US women of child-bearing age.2 Obesity has been described as a risk factor for
respiratory depression in those receiving opioids via any route of opioid
administration,11,15, 17 but whether obesity itself is the risk factor or associated
co-morbidities such as sleep apnea is debated.

Studies are conflicting whether intrathecal opioids or patient controlled intravenous opioids
cause more respiratory depression. Several studies have documented the incidence of
respiratory depression with IV PCA; the rates range from 0.19% to 5.2%, which are equivalent
or higher than those reported for intrathecal opioids. (Hagle 16). Dalchow et al.
demonstrated higher rates of hypercapnia in patients receiving intrathecal opioid compared
with those receiving intravenous opioid via patient controlled analgesia in nonobese women
following cesarean delivery. (Dalchow)

The Topological Oscillation Search with Kinematical Analysis (TOSCA) monitor allows a
noninvasive method to measure transcutaneous carbon dioxide levels, with relative accuracy
compared to arterial carbon dioxide monitoring.4-7 No studies have examined transcutaneous
carbon dioxide levels in obese women following cesarean delivery using any form of
postoperative analgesia. The investigators propose a randomized controlled trial using
continuous transcutaneous carbon dioxide monitoring to evaluate the degree of respiratory
depression in obese women receiving neuraxial opioid compared to intravenous opioid via PCA
for post-cesarean analgesia.

Two studies have demonstrated high rates of hypercapnia in non-obese women following
administration of intrathecal morphine for cesarean delivery in the postpartum period.
(Dalchow, Bauchat) Dalchow et al. demonstrated higher rates of hypercapnia in women receiving
intrathecal diamorphine than intravenous morphine delivered via patient controlled analgesia.
It is unclear whether intrathecal morphine causes more or less respiratory depression than
intravenous opioid delivered via patient-controlled analgesia in obese women.

This study will add to the understanding of respiratory function in the immediate postpartum
period in obese women using opioids via intrathecal or intravenous routes. This study will
better inform guidelines for the postpartum analgesic route of choice in the obese obstetric
population and allow the investigators to make recommendations for the detection and
prevention of respiratory depression after opioid administration in the obstetric population.

Objective is to examine the transcutaneous carbon dioxide levels in obese women using either
intrathecal morphine or intravenous patient-controlled hydromorphone for post-cesarean
analgesia.

The hypothesis is carbon dioxide levels will be significantly higher in obese women receiving
intrathecal morphine versus obese women receiving intravenous patient controlled intravenous
hydromorphone.


Inclusion Criteria:

- Term (≥37 week's gestation)

- Healthy

- ASA class 2-3

- BMI ≥40kg/m2 scheduled for elective cesarean section whose anesthetic plan is for
neuraxial anesthesia (spinal or combined-spinal epidural technique)

Exclusion Criteria:

- Women with ASA >3,

- BMI <40 kg/m2

- Allergy to any of the medications used for pain control

- Contraindication to the spinal anesthetic technique

- Known sleep apnea or other sleep disordered breathing

- Regular use of other medications that cause respiratory depression (ie.
benzodiazepines).
We found this trial at
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Chicago, Illinois 60611
Principal Investigator: Feyce Peralta, MD
Phone: 312-472-3585
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Chicago, IL
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