None listed
Conditions
Brief summary
This project proposes to compare two methods of measuring women’s blood pressure during elective Caesarean sections. The safest and most common type of anaesthetic for a Caesarean section is a spinal anaesthetic. This abolishes painful sensation from the surgery and allows the woman to stay awake while her baby is delivered. However, a common side effect of a spinal anaesthetic is low blood pressure which can cause nausea and vomiting for the mother and may be harmful to the foetus. The pH (acidity) of blood from the umbilical cord taken immediately after delivery is lower (more acidic) if there has been low maternal blood pressure during the Caesarean. Blood pressure is closely monitored by the anaesthetist immediately after the spinal anaesthetic and a drug called metaraminol is given to increase the blood pressure if it is low. Metaraminol works by constricting blood vessels. The most common way of measuring blood pressure is with an automatic cuff on the arm called a noninvasive blood pressure (NIBP) device. This may be set to inflate every one, two or three minutes. However, the reliability of NIBP devices is poor and sometimes they fail to provide a blood pressure reading when required. This is a problem when the blood pressure is so variable in a short time period. An alternative device can provide continuous noninvasive arterial pressure (CNAP) measurement. It measures blood pressure using small cuffs on the finger. This study proposes to compare the reliability of the NIBP device with the CNAP device. Reliability is defined as the ability to provide a blood pressure reading every one minute during a Caesarean section. The main aim is not to compare the accuracy of these two devices. This is already well described in other research. The CNAP device often needs to recalibrate (at least every 15 minutes) and during this period, lasting between 40 and 180 seconds, no blood pressure readings are provided. It is therefore unknown which device is more reliable.
Interventions
Two blood pressure devices will be compared. One is an automated arm cuff oscillometer or NIBP (noninvasive intermittent blood pressure) monitor that will be worn on the left arm. The second is a continuous blood pressure monitor that uses a finger cuff called CNAP (continuous noninvasive arterial pressure). This will be worn on the right hand. The NIBP will be set to inflate every one minute between the time of spinal anaesthesia and delivery of the baby (approximately 15 minutes). The CNAP wil
Two blood pressure devices will be compared. One is an automated arm cuff oscillometer or NIBP (noninvasive intermittent blood pressure) monitor that will be worn on the left arm. The second is a continuous blood pressure monitor that uses a finger cuff called CNAP (continuous noninvasive arterial pressure). This will be worn on the right hand. The NIBP will be set to inflate every one minute between the time of spinal anaesthesia and delivery of the baby (approximately 15 minutes). The CNAP will run continuously but it automatically calibrates every 15 minutes. During recalibration there is a period of 1-2 minutes in which it does not provide a blood pressure reading. The study ceases at delivery for each woman. After delivery, the CNAP monitor will be removed and the NIBP cuff will be set to inflate at a reduced frequency of once per 3-5 minutes.
Sponsors
Thomas McCarthy
Study design
Allocation
Non-randomised trial
Intervention model
Single group
Primary purpose
Diagnosis
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 45 Years
Healthy volunteers
No
Inclusion criteria
Elective Caesarean section under spinal anaesthesia
Exclusion criteria
Hypertensive disorder of pregnancy Peripheral vascular disease Conversion to general anaesthesia prior to delivery Caesarean prior to 32 weeks gestation
Outcome results
None listed