The Severity Of Hypotension Comparing Three Positions During Spinal Anesthesia For Cesarean Delivery

The investigators intend to study the impact of patient positioning on the changes in blood pressure after spinal anesthesia for cesarean delivery. The investigators hypothesized that the changes in blood pressure relate to the speed with which the spinal medication rises. By slowing the rise of spinal anesthesia, the investigators believe that the incidence and severity of hypotension might be reduced.

Study Overview

• Status: Completed
• Conditions: Hypotension
• Intervention / Treatment: Other: Position

Detailed Description

Spinal anesthesia is the most commonly used anesthetic for cesarean delivery. In part, this is due to the ease of administration, reliability and low rates of adverse effects. Additionally, the avoidance of general anesthesia allows the parturient to participate in the birth experience, despite being in surgery.

Although hyperbaric local anesthetic solutions have a remarkable record of safety, their use is not totally without risk. The side effects of spinal anesthesia are well described, but most notably include hypotension (low blood pressure). Spinal hypotension is primarily due to the vasodilatory effects of local anesthetics, and would occur in virtually all women if not prevented or treated.

The incidence of hypotension in both the literature and in clinical practice ranges from 30% to 50% of all patients. Recent literature using a continuous, non-invasive blood pressure monitor suggests that hypotension occurs with greater frequency and may be associated with a higher incidence of adverse effects to either mother or fetus. The incidence and degree of hypotension have been associated with fetal acidosis, which is a sign of either poor perfusion of the placental bed, or increased metabolism due to the blood pressure medications.

The most effective treatment for spinal hypotension is uterine displacement using a hip wedge; the use of a hip wedge after spinal anesthesia is a standard of care. Other treatment, including fluid administration of either crystalloid or colloid, are either partially effective, clinical impractical, or result in administering large doses of medications that may have negative effects on the fetus.

Epidural anesthesia is associated with a reduction in the incidence and severity of hypotension compared with spinal anesthesia. This is believed to be due to the slower onset of sympathetic blockade with epidural anesthesia; this slow onset allows the physiologic compensation to changes in blood pressure. Unfortunately, the slower onset and lower reliability of epidural anesthesia prevents routine use in clinical practice for cesarean delivery.

The investigators hypothesize that the position patients are in during spinal placement might play a role in the severity of maternal hypotension. Interestingly, very few studies have investigated this posibility. Gori, et al. (1) studied influence of seated versus lateral positioning for spinal placement in Cesarean section. They found no significant differences in onset times, Bromage score for motor block, recovery dynamics, and use of ephedrine in two different positions; however, they did not compare the incidence and severity of spinal hypotension. Yun, et al. (2) found that the severity and duration of hypotension were greater when hyperbaric bupivacaine and fentanyl were induced in the sitting position compared to lateral.

Of notice, in all these studies, the authors focused on the immediate positions when the spinal mediation was injected; none has examined the effect of positioning after injection during phase when spinal anesthesia is rising.

Density differences between intrathecal injectate and CSF may explain the observed postural differences in extent of sensory block. Thus, the height of spinal anesthesia blockade could be affected by patient positioning during and after spinal injection. A small incline in positioning immediately after spinal injection may slow the rise of spinal blockade without affecting the duration of spinal anesthesia. In the current protocol, the investigators hypothesize that by slowing the rise of spinal anesthesia, the investigators might reduce the severity of hypotension.

• Study Type: Interventional
• Enrollment (Actual): 105
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02215
      • Beth Isreal Deaconess Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• Singleton pregnancy
• Term gestation
• Scheduled cesarean delivery
• Spinal anesthesia for delivery

Exclusion Criteria:

• Significant fetal concerns
• Polyhydramnios
• Macrosomia
• Morbid obesity (BMI >40)
• Chronic hypertension
• Gestational hypertension
• Preeclampsia
• Type 1 diabetes
• Contraindications to spinal anesthesia

Study Plan

How is the study designed?

Design Details

• Primary Purpose: TREATMENT
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: SINGLE

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Lateral; patient placed in the lateral postion for spinal anesthesia	Other: Position
Active Comparator: Sitting; patient placed in the sitting position for spinal anestheisa, then supine	Other: Position
Active Comparator: Recline; patient placed in the sitting position for spinal anesthesia administration. After spinal placed, the patient turned to a 30-degree upperbody tilt, followed by a slow recline to supine over 5 minutes	Other: Position

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
change in blood pressure	percentage change in blood pressure after spinal anesthesia	20 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
IV fluid administration	Difference in IV fluid requirements	20 minutes

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
IV pressor requirements	Requirements for IV administration of vasopressors	20 minutes

Collaborators and Investigators

• Sponsor: Beth Israel Deaconess Medical Center

Study record dates

Study Major Dates

• Study Start: September 1, 2013
• Primary Completion (Actual): December 1, 2016
• Study Completion (Actual): December 1, 2016

Study Registration Dates

• First Submitted: May 19, 2014
• First Submitted That Met QC Criteria: May 21, 2014
• First Posted (Estimate): May 26, 2014

Study Record Updates

• Last Update Posted (Estimate): January 4, 2017
• Last Update Submitted That Met QC Criteria: January 3, 2017
• Last Verified: January 1, 2017

More Information

Terms related to this study

• Keywords: pregnancy; spinal anesthesia; hypotension
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Hypotension
• Other Study ID Numbers: 2013P000171

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO