Related Experiment Video
Updated: Jun 24, 2026
06:45
Development of a Benchtop Model for Evaluating the Compatibility of Wound Dressing Materials with Negative Pressure Wound Therapy Systems
Published on: May 2, 2025
Critical closing pressure: comparison of three methods
Jorge A López-Magaña1, Hugh K Richards, Danila K Radolovich
1Department of Clinical Neurosciences, Neurosurgery Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.
Summary
Critical closing pressure (CCP) estimation methods were compared in rabbits. Laser-Doppler flux and flow velocity during cardiac arrest showed strong correlation, but transcranial Doppler waveform analysis yielded different CCP values.
Area of Science:
- Cerebrovascular physiology
- Hemodynamics
- Medical engineering
Background:
- Critical closing pressure (CCP) is a vital arterial pressure threshold.
- Understanding CCP is crucial for managing cerebrovascular circulation.
Purpose of the Study:
- To compare methods for estimating CCP in the cerebrovascular circulation.
- To evaluate the relationship between transcranial Doppler flow velocity (FV), laser-Doppler flux (LDF), and arterial blood pressure (ABP) for CCP estimation.
Main Methods:
- Retrospective analysis of 116 rabbit experiments.
- Induction of cardiac arrest (CA) to obtain decreasing arterial blood pressure (ABP) values.
- Estimation of CCP using linear regression between ABP, FV, and LDF during CA.
- Calculation of CCP from FV waveform prior to CA.
Main Results:
- Strong correlation (R=0.98) between CCP estimated using LDF and FV during CA.
- Weaker correlation (R=0.39) between CCP measured during CA and CCP estimated from transcranial Doppler (TCD) waveform.
- CCP calculated from TCD waveform was significantly higher than CCP measured during CA (median difference 9 mm Hg).
- CCP derived from FV waveform and CA correlated with mean intracranial pressure (ICP) before CA.
Conclusions:
- Laser-Doppler flux and flow velocity during cardiac arrest provide reliable CCP estimates.
- Transcranial Doppler waveform analysis for CCP estimation shows significant discrepancies compared to direct measurements during cardiac arrest.
Related Concept Videos
01:21Sites for measuring blood pressure
Blood pressure measurement is a fundamental clinical procedure, providing crucial data for assessing cardiovascular health. Among the various sites for this measurement, the brachial and popliteal arteries are predominantly utilized due to their accessibility and the reliability of their readings. This lesson delves into the anatomical significance, methodology, and considerations of measuring blood pressure at these locations.
The Brachial Artery: Primary Site for Blood Pressure Measurement
The Brachial Artery: Primary Site for Blood Pressure Measurement
01:23Assessment of blood pressure in brachial artery(two-step method)
Measuring blood pressure is a fundamental skill in healthcare that aids in diagnosing and monitoring hypertension and other cardiovascular conditions. An aneroid sphygmomanometer, commonly used in clinical settings, offers a manual and precise method for blood pressure measurement. The technique for using this instrument involves specific steps that must be carefully executed to ensure accuracy. The following detailed description outlines a two-step technique for assessing blood pressure using...
01:16Measurement of Fluid Pressure
Fluid pressure is commonly measured using devices called manometers, which rely on liquid columns to indicate pressure differences. The height of a liquid column in a manometer reflects the pressure exerted by the fluid, providing a simple yet effective means of measurement. Different types of manometers serve specific purposes based on their configurations and the type of fluids involved.
A basic form of manometer is the piezometer, a vertical tube open at the top and filled with the same...
A basic form of manometer is the piezometer, a vertical tube open at the top and filled with the same...
01:24Pressure Relationships in Thoracic Cavity
Breathing, otherwise known as pulmonary ventilation, is the process of air movement into and out of the lungs. The main mechanisms propelling pulmonary ventilation are atmospheric pressure (Patm), intra-pulmonary (Ppul ) or intra-alveolar pressure (Palv) within the alveoli, and intrapleural pressure (Pip) within the pleural cavity.
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
01:30Equipments Used To Measure Blood Pressure
Direct Method
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...
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...
01:24Static, Stagnation, Dynamic and Total Pressure
The concept of static, stagnation, dynamic, and total pressure is fundamental in fluid dynamics, often explained using Bernoulli's equation: