CNAP vs IABP in Pregnant Women With Placenta Accreta

The objective of this study is to investigate a technique to monitor blood pressure in women undergoing cesarean delivery with suspected placenta accreta spectrum. To achieve this objective, the investigators plan to conduct a prospective, observational study with the following aims:

Specific Aim 1: Compare concordance between the systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MAP) readings from the continuous non-invasive arterial blood pressure (CNAP) and IABP at several discrete points throughout the procedure

Specific Aim 2: Determine the feasibility of using CNAP to aid in decision making by examining the parameters of volume responsiveness and arterial elastance at several discrete points throughout the procedure.

The investigators hypothesize that the investigators can obtain similar blood pressure monitoring using CNAP as compared to the gold standard IABP in women undergoing cesarean delivery with suspected placenta accreta.

Study Overview This is a prospective, observational study.

Study Procedures Patients who meet inclusion criteria with no exclusions will be approached to provide written informed consent.

Enrolled patients will undergo the standard pre-operative evaluation and preparation for cesarean section with possible hysterectomy including evaluation by nursing, obstetrics and anesthesiology team, placement of 2 large bore IVs, arterial line placement and laboratory tests.

The patient will then be transported to the OR. In the OR the CNAP device will be placed on the patient's finger and be given a brief calibration period of 45 seconds. As per usual for this procedure, each patient will undergo combined spinal epidural anesthesia with our standard cesarean induction dose of hyperbaric intrathecal 0.75% bupivacaine 1.5ml, intrathecal fentanyl 25 micrograms and intrathecal morphine 250 micrograms. The patient will be moved to the supine position with left lateral uterine displacement. When a T6 sensory level to pinprick is achieved, surgery will be allowed to proceed. Throughout the surgery, the CNAP and IABP will take continuous reading of blood pressure and hemodynamic variable. Labs and additional fluid or blood may be given to the patient as clinically indicated, as is common for this procedure. Blood work will be obtained from the arterial line used for IABP, as is standard practice when an AIBP is in place. Other than the addition of the CNAP cuff, all other care will be per standard protocol for this procedure.

Data Collection In order to assess our primary and secondary outcomes, the investigators will be collecting CNAP and AIBP. Additional baseline characteristics including, but not limited to age, race, gender, BMI and comorbidities will be abstracted from the medical record. REDCap will be utilized for data collection and storage.

Primary Outcomes SBP, MAP, DBP reading from the CNAP and AIBP at several discrete points throughout the procedure.

Secondary Outcomes Additional comparisons of SBP, MAP, DBP measurements using CNAP to AIBP and NIBP, review of extrapolated data outputs including Stroke Volume, Systemic Vascular Resistance, Cardiac Output and Stroke Volume Variation from CNAP compared pulse pressure index from pulse oximetry and AIBP and their responsiveness to fluid bolus, subgroup analysis of CNAP and AIBP during times significant intravascular volume depletion (blood loss) or systemic vascular resistance change (after spinal anesthesia). Relevant clinical data will also be collected, including; demographic data, total estimated blood lose, total quantitative blood loss, length of hospital stay, routine lab results including; Hematocrit, Fibrinogen, coagulation tests, lactic acid, pH, base excess.

Eligibility Criteria:
Inclusion Criteria:

* Women aged 18-40 years old with pregnancy complicated by accreta spectrum undergoing elective, scheduled cesarean delivery and possible hysterectomy

Exclusion Criteria:

* Women aged \<18
* Patients with cardiac arrhythmia
* Vascular pathologies of the upper limbs (recent vascular surgery, Reynaud's disease, vascular stenosis)
* Contraindication to neuraxial anesthesia
* Emergent cases
* Droplet or airborne precautions (as determined by BIDMC infection control policy)