Background:
Enhanced Recovery After Surgery (ERAS) is a concept that aims to achieve faster patient
recovery and fewer complications after major surgery. Spinal anesthesia is a technique
widely used for Cesarean Delivery (CD), where a local anesthetic is administered along
with opioids such as fentanyl and morphine. Antiemetic agents have been used
prophylactically during CD under spinal anesthesia. The efficacy of combination
antiemetic agents to prevent nausea and vomiting in patients who underwent CD has been
established, hence, a multi-modal anti-emetic approach has been advocated for ERAS for
CD.
Dexamethasone is a corticosteroid that has been found to significantly prevent nausea and
vomiting and decrease postoperative pain. Dexamethasone has been shown to prolong the
durations of sensory and motor blockade for peripheral nerve blocks. Despite the
knowledge that dexamethasone is a useful adjunct for extending local anesthetic duration
and reducing postoperative pain, only one study has examined its application in spinal
anesthesia for CD. In this study, authors found 8mg of IV dexamethasone increased the
mean duration of sensory block by 56 minutes, which was highly significant. The extended
duration of anesthesia can have several unintended consequences such as extending stay in
the post anesthesia recovery unit (PACU), impairing mother and baby bonding, and
utilizing healthcare resources as nurses have to stay with the patient longer limiting
the ability to complete another elective CD.
Recognizing the perioperative movement towards adopting ERAS strategies, dexamethasone
will be a routine adjunct to prevent spinal associated nausea and vomiting. Formally
quantifying the effect IV dexamethasone has on spinal anesthesia for CD will help
anesthesia providers decide whether to administer IV dexamethasone intraoperatively. For
example, if providers are hoping to extend the length of the spinal blockade (prolonged
surgical duration) they could choose dexamethasone as the second multi-modal antiemetic.
Alternatively, anesthesia providers could omit IV dexamethasone, and use an alternative
anti- emetic such as metoclopramide, to promote rapid discharge from the PACU, improving
perioperative efficiency and health utilization.
The investigators hypothesize that in healthy parturients having elective CD, 10 mg IV
dexamethasone will increase the duration of motor blockade from spinal anesthesia using
0.75% bupivacaine, lengthening the time spent in PACU.
Design & Procedure:
This is a randomized double-blind controlled clinical trial in non-laboring parturients
presenting for elective CD.
The spinal anesthesia technique will be standardized and will be administered as per
routine care at IWK Health. Each patient will receive 12 mg of 0.75% hyperbaric
bupivacaine with 10 micrograms of fentanyl and 100 micrograms of epidural morphine via a
25-gauge Whitacre spinal needle. Computer generation will randomize patients to either
Group SD, who will receive IV dexamethasone 10 mg (1mL), or group SM who will receive IV
metoclopramide 10 mg (2 mL) (alternative anti-emetic), immediately after spinal
anesthesia by the attending anesthesia provider. Additionally, each patient will receive
ondansetron 4mg IV, immediately after spinal anesthesia (second anti-emetic as
recommended for ERAS protocol). If a third anti-emetic is required for ongoing nausea and
vomiting in the operating room or PACU, dimenhydrinate 12.5- 25 mg IV can be provided for
both groups. If a fourth anti-emetic is required for ongoing nausea and vomiting in the
operating room or PACU, haloperidol 0.5mg IV can be provided for both groups. All
anti-nausea medications administered will be tracked on the data collection record (DCR).
The randomization assignments will be placed in a sealed envelope by a research staff
member who is not participating in clinical data collection. The randomization log will
be kept in a secure/locked research office. The randomization envelope will be provided
to the attending anesthesiologist by a research team member on the morning of surgery.
All drugs will be prepared and administered by the attending anesthesiologist, who will
not be blind. The patient and research team assessor will be blinded to treatment
allocation.
Sensation will be tested using ice and quality of motor block will be assessed using
modified Bromage score. In PACU, research personnel, unaware of the subject's
randomization, will assess motor blockade unilaterally every 15 minutes until a Bromage
score of 3 is present. That time will be entered on the DCR, and the patient will be
assessed more frequently (every 3-5 minutes) until a Bromage of 4 is achieved and
confirmed bilaterally with a second assessment 1-minute later. If needed, assessments
will continue to occur every 3-5 minutes until a Bromage score of 4 is reached
bilaterally. Sensation will be assessed every 15 minutes unilaterally. When sensation is
reached at L3, a bilateral assessment will be taken, and the time will be recorded. If
needed, assessments will continue to occur every 15 minutes. The time will be recorded on
the DCR when sensation at L3 is reached bilaterally.
Numeric Rating Scale (NRS) scores for pain and nausea intensity will be collected every
hour postoperatively until a Bromage score of 4 is achieved. The time of opioid use and
total opioid dose in the first 24 h will be recorded during the PACU stay and from
medical chart review. The incidence of pruritus (itching) and vomiting will also be
assessed prior to PACU discharge.
Data Analysis:
In keeping with CONSORT guidelines, all subjects enrolled will be included in an
intention to treat analysis. Descriptive statistics will be expressed as mean +/-
standard deviation. Demographics (height, weight, etc.) will be analyzed using Student's
t-test. Nonparametric testing (Mann-Whitney U test) will be used to evaluate NRS pain
scores, opioid consumption and sensory and motor duration. Categorical data (nausea and
vomiting) will be analyzed using the x2 test or Fisher's exact test, as appropriate. The
investigators will perform the statistical analysis with the assistance of the consulting
departmental statistician.
With power of 90% and confidence interval of 95% (α = 0.05), a clinically meaningful
change in recovery time of 15 minutes with a (generous) anticipated standard deviation of
33, 116 participants are required (58 per group). It is anticipated that the standard
deviation could be smaller than this, which would mean that the investigators could be
powered to detect a 15-minute difference at α = 0.05 with fewer than 116 participants.
116 is a conservative estimate to ensure that the investigators have the power needed to
test the primary hypothesis.
