Spinal Induced Hypotension in Cesarean Delivery
Conditions
Brief summary
This study is designed to determine the ED90 for an infusion of phenylephrine to prevent spinal induced low blood pressure in parturients presenting for an elective cesarean delivery. The up-down methodology (UDM) is commonly used study method to determine the dose of a drug that causes the desired effect in over 90% of the subjects to whom it given. For example: the investigators want to know what is the best dose of phenylephrine (from a range of commonly used doses) to prevent a drop in blood pressure during cesarean delivery ninety times out of one hundred when it is given at that dose. The ED90 is the effective dose at which 90% of subjects will have a positive response to a phenylephrine infusion, i.e. no drop in blood pressure. The investigators hypothesize that the ED90 will be between 40 - 60 mcg/min. The primary outcome measure is the ED90 for phenylephrine infusions that prevents a drop in blood pressure in women undergoing cesarean delivery.
Interventions
Up-down, biased coin design
Sponsors
IWK Health Centre
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
FEMALE
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
1. Non-emergent cesarean delivery with planned spinal anesthesia (i.e. elective planned cesarean delivery for malposition, patient choice, cervical pelvic disproportion, previous cesarean delivery and other diagnosis that require a predetermined cesarean delivery) 2. American Society of Anesthesia physical status class I & II (ASA I - Healthy, ASA II - mild and controlled systemic disease, eg. controlled essential hypertension) 3. Age ≥ 18 years (Standard within the obstetrical literature) 4. Term gestational age 5. English-speaking
Exclusion criteria
1. Morbid Obesity (Body Mass Index ≥ 45 kg/m2) (Morbidly obese parturients require a dose of local anesthetic less than the standardized dose in this study, typically have an exaggerated response to vasopressors, and the blood pressure cuff occasionally needs to be replaced by an intra-arterial catheter due to limitations in size) 2. Height \< 5'0 (Women \< 5'0 are likely to require a dose of local anesthetic less than the standardized dose in this study) 3. Laboring women 4. Urgent or emergency cesarean delivery 5. Hypertensive disease of pregnancy 6. Severe maternal cardiac disease 7. Subjects on monoamine oxidase inhibitors (MAOI's) or tricyclic antidepressants 8. Fetal anomalies or intrauterine fetal death 9. Failed spinal anesthesia 10. Subject enrollment in another study involving a study medication within 30 days of CD 11. Any other physical or psychiatric condition which may impair their ability to cooperate with study data collection
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Effective Dose of Phenylephrine at Which 90% of Subjects Have no Spinal Induced Hypotension | Spinal administration until delivery | The effective dose at which 90% of subjects will have a positive response to a phenylephrine infusion, i.e. no spinal induced hypotension. We hypothesize that the ED90 will be between 40 - 60 mcg/min. |
Participant flow
Pre-assignment details
Six subjects were withdrawn from the study
Participants by arm
| Arm | Count |
|---|---|
| Phenylephrine Infusion Phenylephrine infusion : Up-down, biased coin design | 46 |
| Total | 46 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | experienced hypotension requiring tx | 6 |
Baseline characteristics
| Characteristic | Phenylephrine Infusion |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 46 Participants |
| Sex: Female, Male Female | 46 Participants |
| Sex: Female, Male Male | 0 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | — / — |
| other Total, other adverse events | 0 / 40 |
| serious Total, serious adverse events | 0 / 40 |
Outcome results
Primary
Effective Dose of Phenylephrine at Which 90% of Subjects Have no Spinal Induced Hypotension
The effective dose at which 90% of subjects will have a positive response to a phenylephrine infusion, i.e. no spinal induced hypotension. We hypothesize that the ED90 will be between 40 - 60 mcg/min.
Time frame: Spinal administration until delivery
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Phenylephrine Infusion | Effective Dose of Phenylephrine at Which 90% of Subjects Have no Spinal Induced Hypotension | NA dose of phenylephrine |