Related Experiment Video
Updated: Mar 18, 2026

Continuous Venous-Arterial Doppler Ultrasound During a Preload Challenge
Published on: January 20, 2023
CONTINUOUS NON-INVASIVE ARTERIAL PRESSURE DEVICE AS AN ADJUNCT TO RECOGNIZE FLUCTUATING BLOOD PRESSURES DURING
Background:
Measuring non-invasive blood pressure (NIBP) in less than one minute intervals (STAT NIBP measurements) is not always feasible. Therefore, large number of undetectable hypotension episodes can only be recognized with continuous beat to beat monitoring of blood pressure, for example, by continuous non-invasive arterial pressure monitor (CNAP).
Objective:
The purpose of the current study was to investigate whether CNAP correlates well with conventional intermittent oscillometric NIBP during elective cesarean sections under subarachnoid blockade (SAB) and whether CNAP based patient management results in improved immediate maternal vasopressor requirements and improved immediate fetal/neonatal outcomes compared with NIBP based patient management.
Materials And Methods:
The CNAP finger cuff together with the CNAP arm cuff were placed on the same arm which also had the peripheral intravenous access.. On the contralateral arm the conventional NIBP arm cuff was placed. Study Group: The patients were managed by the anesthesia provider based on the CNAP monitor readings. Control Group: The patients were managed by the anesthesia provider based on the NIBP monitor readings. Results: The CNAP-based treatment (study) group had a statistically significant lower use of oxytocin and lower estimated blood loss than the NIBP-based treatment (control) group. The differences in incidences of vasopressors use and peri-operative nausea vomiting between study group and control group did not reach statistical significance. CNAP readings were more likely to be in systolic hypotensive phases (
Conclusion:
Continuous non-invasive arterial pressure (CNAP) device may ONLY act as an adjunct to recognize fluctuating blood pressures during elective cesarean section under subarachnoid blockade (SAB).
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Equipments Used To Measure Blood Pressure
This invasive approach involves cannulating a peripheral artery. During each cardiac contraction, pressure generates mechanical motion within the catheter, transmitted through rigid, fluid-filled tubing to a transducer. This transducer converts mechanical motion into electrical signals displayed as waveforms on a monitor. An automatic flushing system prevents blood backflow. Due to the potential risk of unexpected arterial blood loss, this method is primarily used in intensive...
Sites for measuring blood pressure
The Brachial Artery: Primary Site for Blood Pressure Measurement
Special considerations while measuring blood pressure
Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
Pre-Procedural Guidelines for Assessing Blood Pressure
Assessment of blood pressure in brachial artery(two-step method)
Assessing Blood pressure using a doppler ultrasound
Pre-Procedural Guidelines for Doppler Ultrasound Blood Pressure Assessment:
Preparation of Equipment:

