Undetectable Hypotension Episodes in Cesarean Section

Can We Detect Hypotension Episodes That Were Not Identified in the Non-Invasive Blood Pressure During Cesarean Section? A Randomized Controlled Trial

In order to evaluate the efficacy and necessity of continuous non-invasive arterial pressure (CNAP) by comparing it with non-invasive blood pressure (NIBP) in order to understand whether it has advantages over oscillometric technique for detection of hypotensive episodes in healthy pregnant women who underwent cesarean section (C/S) under neuraxial anesthesia. This prospective study will evaluate healthy pregnant women at term, who were scheduled for elective C/S under spinal anesthesia. Subjects were randomly assigned into 2 groups to receive either CNAP and NIBP or only NIBP. A thirty percent decrease in systolic blood pressure from either baseline or the measured values in the first two minutes, or if the systolic blood pressure was less than 90mmHg, is considered hypotension. Pre-, peri- and post-operative specifications, newborn characteristics, and complications were recorded and compared.

Study Overview

• Status: Completed
• Conditions: Pregnancy Related; Blood Pressure; Anesthesia
• Intervention / Treatment: Device: Continuous non-invasive arterial pressure (Infinity® CNAPTM, Dräger)

Detailed Description

The aim of the study was to test the hypothesis that whether continuous non-invasive arterial pressure (CNAP) is able to identify the hypotensive episodes that were not disclosed (or identified) in the non-invasive blood pressure (NIBP), or, detects earlier compared to NIBP in healthy pregnant women who underwent C/S under neuraxial anesthesia. We also evaluated the association between monitoring CNAP vs NIBP and outcomes as a secondary endpoint.

At least 40 participants were planned to be included in each arm, considering the unforeseen technical problems (in accordance with the "Power and Sample Size Program", the inclusion of at least 29 patients was necessary for both groups for a power 0.80, alpha 0.05 and a standard deviation of 0.04).

Healthy pregnant women at term, who were scheduled for the elective C/S under spinal anesthesia in an academic tertiary care unit between February 2014 and February 2015, comprised the study group. The exclusion criteria for the study were; 1) emergency C/S, 2) simultaneous gynecological interventions with C/S such as myomectomy, tubal ligation, placental abnormalities, etc., 3) if C/S was performed in failure of labor to progress, 4) the presence of any systemic disease, 5) preeclampsia or eclampsia, 6) drug hypersensitivity - for the ones that are used in the C/S -, 7) multiple pregnancies, 8) those pregnancies with any intrauterine fetal pathology, and 9) more than two missing consecutive NIBP readings.

Subjects were randomly assigned into 2 groups to receive either CNAP and NIBP or only NIBP. CNAP finger cuff (Infinity® CNAPTM, Dräger) was used for calibrate the device before the first measurement then calibration was repeated every 30 minutes.

In the CNAP group, the CNAP finger cuff and NIBP cuff were on the same arm of the patient while the intravenous catheter was on the contralateral side. In the control group, only oscillometric NIBP measurements were done in pregnant women similar to the study group without a CNAP.

After intrathecal injection, systolic, diastolic, and mean blood pressures were measured and were recorded manually at every minute on the CNAP monitor, and the oscillometric NIBP measurements were set at the frequency of 3 minutes for the first 15 minutes, and at 5-minute intervals thereafter, and were recorded manually.

Demographic and pregnancy-related characteristics (age, parity, gravidas of the pregnant women, weeks of gestation, and the type of fertilization [spontaneous or in vitro fertilization (IVF)] were recorded.

All parturients underwent C/S after 8 hours of fasting period without any pharmacological premedication. They were monitored with 5 lead electrocardiograms, and pulse oximetry in the operating theater. By providing the monitorization, a total of 1000ml of Ringer's lactate infusion was given by an intravenous line with an 18-gauge cannula as pre-load/co-load. A 12.5 mg of hyperbaric bupivacaine was administered to all pregnant women in the left lateral decubitus position with a 26-gauge atraumatic spinal needle at the L3-4 or L4-5 interval. After the spinal injection, the patients were placed in a supine position, and the uterus was directed to the left side by using a support under the right hip. Oxygen was given to all the parturients at 3 lt / min by nasal cannula.

The block-level was assessed by loss of sensitivity to cold. When it reached the T4 skin dermatome, the surgery was started. Motor block was determined and recorded using the modified Bromage scale (0 = no block, 1 = knee flexion possible, leg unable to lift, 2 = ankle flexion and finger movements possible, unable to move the knee, 3 = full motor block in the lower extremity). The sensitivity to cold was checked every 5 minutes and the maximum block level was recorded. Analgesia was evaluated using a visual analog scale scorer (0 = no pain, 10 = most severe pain). Time from intrathecal injection to delivery (block-delivery time), time from skin incision to delivery (skin-birth time), time from uterine incision to delivery (uterus-delivery time) were recorded.

After the baby was born, the mother was sedated with midazolam 0.03 mg/kg so that the Ramsay sedation score was 2, and analgesia was provided with fentanyl 0.5 μg/kg if necessary. As the umbilical cord was clamped, 2g of cephalosporin and 5 IU of oxytocin were administered intravenously, and 15 IU oxytocin in 1000 ml Ringer's lactate was infused in an hour.

Peri/Post-Operative Periods Patients with a thirty percent decrease in systolic blood pressure from either baseline or the measured values in the first two minutes, or with systolic blood pressure less than 90mmHg; which is considered as hypotension (13), were treated with a bolus of 200 ml Ringer's lactate solution. If blood pressure did not improve after 3 minutes, 5 mg intravenous ephedrine was administered.

A decrease in heart rate below 50 beats/min was considered as bradycardia, and 0.5mg intravenous atropine was administered when encountered.

The nausea-vomiting score was calculated as follows; the absence of nausea -0, nausea without vomiting -1, and vomiting -2 points.

Patient discomfort for non-invasive blood pressure cuff and CNAP cuff scored was as 0, 1, 2, and 3 for; no discomfort, mild discomfort, moderate discomfort, and severe discomfort, respectively.

The amount of administered intravenous fluids and ephedrine during anesthesia, the umbilical artery blood gas values, and APGAR scores at 1st minute, and at 5th minutes were also recorded.

Complications, ie, postoperative fever, bleeding, need a transfusion for blood and blood products, aspiration, atelectasis, and postspinal headache, were noted at the postoperative 24th and 48th hours. The length of stay hospital stay for the mother and baby, the requirement for intensive care unit, and/or mechanical ventilator were assessed, separately.

• Study Type: Observational
• Enrollment (Actual): 53

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Probability Sample

Study Population

The study group consisted of pregnant women at term, who were scheduled for the elective (planned) C/S under spinal anesthesia in an academic tertiary care unit. Subjects were randomly assigned into 2 groups to receive either CNAP and NIBP or only NIBP.

Description

Inclusion Criteria:

• Pregnant women at term, who were scheduled for the elective (planned) C/S under spinal anesthesia

Exclusion Criteria:

• emergency C/S,
• simultaneous gynecological interventions with C/S such as myomectomy, tubal ligation, placental abnormalities, etc.,
• C/S that was performed in failure of labor to progress,
• the presence of any systemic disease,
• preeclampsia or eclampsia,
• hypersensitivity to drugs that are used in C/S,
• multiple pregnancies,
• pregnancies with any intrauterine fetal pathology,
• cases with more than two missing consecutive NIBP readings.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
CNAP Group; The CNAP finger cuff and NIBP cuff were on the same arm of the patient while the intravenous catheter was on the contralateral side. After intrathecal injection, systolic, diastolic, and mean blood pressures were measured and were recorded manually at every minute on the CNAP monitor.	Device: Continuous non-invasive arterial pressure (Infinity® CNAPTM, Dräger); The basic working principle of CNAP is to keep the blood volume of the finger arteries constant by applying an exterior pressure to the vessel wall, that is done by an electronic system controlling the pressure inside a cuff around the finger. The pressure in the cuff, which is needed to keep the volume constant during arterial pulsation, corresponds to the AP.
NIBP Group; In the control group, only oscillometric NIBP measurements were done in pregnant women similar to the study group without a CNAP. After intrathecal injection, systolic, diastolic, and mean blood pressures with oscillometric method were set at the frequency of 3 minutes for the first 15 minutes, and at 5-minute intervals thereafter, and were recorded manually.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Detection of hypoptensive episodes	Hypotensive	Approximately 100minutes/patient (till the end of the C/S).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The association between monitoring CNAP vs NIBP and other related outcomes - Anesthesia time to reach T4 level	Anesthesia time to reach T4 level (minutes)	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - Skin incision time (minutes)	Skin incision time (minutes)	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - Uterine incision time (minutes)	Uterine incision time (minutes)	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - Time to leave the operating theater (minutes)	Time to leave the operating theater (minutes)	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - Intraoperative fluid (ml)	Intraoperative fluid (ml)	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - The need and amount of ephedrine used	The need (number of patients) and amount (mg) of ephedrine used	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - Bolus of 200 ml Ringer's lactate solution	The need (number of patients) of bolus 200 ml Ringer's lactate solution	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - Nausea	Nausea (number of patients)	After C/S - early postoperative period - through study completion, an average of 1 year
The association between monitoring CNAP vs NIBP and other related outcomes - Vomiting	Vomiting (number of patients)	After C/S - early postoperative period - through study completion, an average of 1 year
The association between monitoring CNAP vs NIBP and other related outcomes - Length of Hospitalization (days)	Length of Hospitalization (days)	Length of Hospitalization - through study completion, an average of 1 year
The association between monitoring CNAP vs NIBP and other related outcomes - Cuff discomfort	Cuff discomfort (Scale based: No - Mild - Moderate or Severe)	Approximately 100minutes/patient (till the end of the C/S).
The association between monitoring CNAP vs NIBP and other related outcomes - Newborns' Blood Gas Analysis	Newborns' Blood Gas Analysis - Umblical Artery pH	At the time of birth - through study completion, an average of 1 year
The association between monitoring CNAP vs NIBP and other related outcomes - Newborns' Blood Gas Analysis	Newborns' Blood Gas Analysis - Umblical Artery pO2	At the time of birth - through study completion, an average of 1 year
The association between monitoring CNAP vs NIBP and other related outcomes - Newborns' Blood Gas Analysis	Newborns' Blood Gas Analysis - Umblical Artery pCO2	At the time of birth - through study completion, an average of 1 year
The association between monitoring CNAP vs NIBP and other related outcomes - Newborns' Blood Gas Analysis	Newborns' Blood Gas Analysis - Umblical Artery Lactate	At the time of birth - through study completion, an average of 1 year
The association between monitoring CNAP vs NIBP and other related outcomes - Newborns' APGAR score	Newborns' APGAR score	After birth at 1st minute
The association between monitoring CNAP vs NIBP and other related outcomes - Newborns' APGAR score	Newborns' APGAR score	After birth at 5th minutes

Collaborators and Investigators

• Sponsor: Asude AYHANt
• Investigators: Principal Investigator: Aynur C FIRAT, M.D., Baskent University School of Medicine, Department of Anaesthesiology and Reanimation

Publications and helpful links

General Publications

• Ngan Kee WD. Prevention of maternal hypotension after regional anaesthesia for caesarean section. Curr Opin Anaesthesiol. 2010 Jun;23(3):304-9. doi: 10.1097/ACO.0b013e328337ffc6.
• Ilies C, Kiskalt H, Siedenhans D, Meybohm P, Steinfath M, Bein B, Hanss R. Detection of hypotension during Caesarean section with continuous non-invasive arterial pressure device or intermittent oscillometric arterial pressure measurement. Br J Anaesth. 2012 Sep;109(3):413-9. doi: 10.1093/bja/aes224. Epub 2012 Jul 12.
• Ilies C, Bauer M, Berg P, Rosenberg J, Hedderich J, Bein B, Hinz J, Hanss R. Investigation of the agreement of a continuous non-invasive arterial pressure device in comparison with invasive radial artery measurement. Br J Anaesth. 2012 Feb;108(2):202-10. doi: 10.1093/bja/aer394. Epub 2011 Dec 12.
• Gupta D, Soskin V, Marjanovic M, Amhaz H, Mazumdar A. CONTINUOUS NON-INVASIVE ARTERIAL PRESSURE DEVICE AS AN ADJUNCT TO RECOGNIZE FLUCTUATING BLOOD PRESSURES DURING ELECTIVE CESAREAN SECTION UNDER SUBARACHNOID BLOCKADE (SAB). Middle East J Anaesthesiol. 2016 Feb;23(4):385-400.
• Hahn R, Rinosl H, Neuner M, Kettner SC. Clinical validation of a continuous non-invasive haemodynamic monitor (CNAP™ 500) during general anaesthesia. Br J Anaesth. 2012 Apr;108(4):581-5. doi: 10.1093/bja/aer499. Epub 2012 Feb 3.

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2014
• Primary Completion (Actual): August 1, 2014
• Study Completion (Actual): February 1, 2015

Study Registration Dates

• First Submitted: June 8, 2022
• First Submitted That Met QC Criteria: June 27, 2022
• First Posted (Actual): July 1, 2022

Study Record Updates

• Last Update Posted (Actual): July 1, 2022
• Last Update Submitted That Met QC Criteria: June 27, 2022
• Last Verified: June 1, 2022

More Information

Terms related to this study

• Keywords: Cesarean section; Blood pressure; Anesthesia; Newborn; Obstetrical; Arterial pressure
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Hypotension
• Other Study ID Numbers: KA13/33

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: When the study is completed and totally shaped out as an academic manuscript, the individual participant data (IPD) will be available to other researchers.
• IPD Sharing Time Frame: The data will become available when the related manuscript is published in a scientific journal. So, the researchers will be able to reach the manuscript whenever they want-upon the regulations of the published journal.
• IPD Sharing Access Criteria: Access will be done throughout the journal's website or digital object identifier system (DOI).
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No