The Use of P6 Acupressure for the Reduction of Intraoperative and Postoperative Nausea and Vomiting in Women Undergoing Cesarean Delivery: a Randomized Trial

After obtaining written informed consent from the subject. They were then randomized to either the P6 acupressure or a sham acupressure group. Envelopes containing group assignment information were prepared prior to the start of the study by research personnel not involved in this study. Randomization occurred by selecting a sealed envelope that contained the group assignment, two acupressure 0.09-inch by 0.2-inch diameter devices, and a diagram of where to place the device from a pool of 200 envelopes. The acupressure devices used in this study are also used in clinical practice by Northwestern Medicine Osher Center for Integrative Medicine (Plaster - Accu Band 800 NP Magnets, Japan). Prior to the commencement of the study, the Center for Integrative Medicine acupuncturists educated study personnel on the placement of the devices and the proper patient-initiated stimulation method when the subject began to perceive nausea. Device placement took place in the preoperative room, prior to walking to the operating room for the surgical procedure, by research personnel not involved in the clinical care of study subjects. In the P6 acupressure group, the devices were placed two inches proximal to the flexor retinaculum, between the flexor carpi radialis and palmaras longus bilaterally. The small protrusion on the device was placed on the skin and held in place using an adhesive sticker at the stimulation point. In the sham acupressure group, the devices were placed distal and lateral to the P6 acupoint site, like in prior studies comparing the effectiveness of P6 acupressure to sham. This method of sham acupoint placement when compared to P6 acupoint placement has shown superiority of the P6 acupoint placement in 70% of studies that have used this point for sham.15 The devices are designed to maintain pressure at the point of placement without additional force applied. Research personnel also instructed subjects to apply additional pressure at the acupressure site for a period of 30 s-2 min if they perceived nausea. Subjects were then taken to the operating room where they received neuraxial anesthesia consisting of either a spinal anesthetic dosed with hyperbaric bupivacaine 12 mg plus fentanyl 15 mcg and morphine 150 mcg, or a combined spinal epidural with the same intrathecal dosing per institutional standard practice. Co-loading with a crystalloid solution occurred upon the start of the neuraxial procedure, and a phenylephrine infusion was started immediately after the cerebrospinal fluid was obtained. Maternal hypotension was defined as a systolic blood pressure less than 100 mmHg, mean arterial pressure less than 65 mmHg, or mean arterial pressure less than 20% of the baseline mean arterial pressure. The baseline blood pressure was considered the average value of three blood pressure readings obtained by the nursing staff in the preoperative area. Subjects were asked to report any nausea, retching, or vomiting to the anesthesia care team. In addition, the anesthesia provider asked the study subject about nausea or vomiting at intervals corresponding to events that are associated with a greater prevalence of nausea and vomiting (e.g. neuraxial dose administration, uterine exteriorization, and following uterotonic administration) as well as when the anesthesia provider observed the subject massaging the acupressure point. After the first complaint of nausea, subjects were encouraged to apply additional pressure to the devices, an intravenous (IV) fluid bolus was administered, and phenylephrine or ephedrine was administered by IV bolus and/or by increasing the infusion rate of phenylephrine if hypotension was present. At the second complaint of nausea or emesis, study subjects were again encouraged to apply additional pressure on the devices. Following delivery of the fetus, ondansetron 8 mg IV and dexamethasone 8 mg IV were administered. If intraoperative nausea and/or vomiting continued, study subjects were again encouraged to apply additional acupressure. If this was ineffective, prochlorperazine, promethazine, metoclopramide, fentanyl, or propofol were administered at the anesthesiologist's discretion. If these antiemetic agents were ineffective, the anesthesiologist could provide additional medications.

Routine postoperative orders, including antiemetic medications as needed, were placed by the anesthesiology team for postpartum use per our institution's current standard of care. Postoperative medications were administered and documented by the nursing staff. Study subjects were also encouraged to use additional acupressure as needed throughout their postoperative course, for up to 48 h or until discharge, whichever came first. A study team member replaced devices that were lost or removed the device if the study subject requested it. Prior to discharge, subjects were visited by study personnel and asked to complete a survey asking them to describe the incidence, duration, and severity of nausea and vomiting, interference of nausea/vomiting with the ability to care for themselves, and their rating and satisfaction of the acupressure therapy.

Baseline data collected were age, weight, height, body mass index, American Society of Anesthesiologists physical status classification, race, ethnicity, history of nausea and vomiting, parity, and the number of prior cesarean delivery. Intraoperative data included the type of neuraxial anesthesia, initial blood pressure in the operating room, the lowest recorded blood pressure intraoperatively, total vasopressor use (expressed as phenylephrine equivalents),18 the number of hypotensive episodes, crystalloid administered, and duration of anesthesia. Intraoperative nausea and vomiting outcomes included the number of subjects with nausea and/or vomiting, the number of emesis episodes, and the need for rescue antiemetic administration in the operating room. Post delivery emesis and antiemetic treatments were recorded in the post anesthesia care unit (PACU) in 0-24 h and 24-48 h periods. Study subject questionnaires were collected at the end of the study period.