Blood Pressure Monitoring for the Anesthesiologist: A Practical Review

Abstract

Periodic, quantitative measurement of blood pressure (BP) in humans, predating the era of evidence-based medicine by over a century, is a component of the American Society of Anesthesiologists standards for basic anesthetic monitoring and is a staple of anesthetic management worldwide. Adherence to traditional BP parameters complicates the ability of investigators to determine whether particular BP ranges confer any clinical benefits. The BP waveform is a complex amalgamation of both antegrade and retrograde (reflected) pressure waves and is affected by vascular compliance, distance from the left ventricle, and the 3D structure of the vascular tree. Although oscillometry is the standard method of measuring BP semicontinuously in anesthetized patients and is the primary form of measurement in >80% of general anesthetics, major shortcomings of oscillometry are its poor performance at the extremes and its lack of information concerning BP waveform. Although arterial catheterization remains the gold standard for accurate BP measurement, 2 classes of devices have been developed to noninvasively measure the BP waveform continuously, including tonometric and volume clamp devices. Described in terms of a feedback loop, control of BP requires measurement, an algorithm (usually human), and an intervention. This narrative review article discusses the details of BP measurement and the advantages and disadvantages of both noninvasive and invasive monitoring, as well as the principles and algorithms associated with each technique.

Heated humidified high-flow nasal cannula oxygen after thoracic surgery — A randomized prospective clinical pilot trial

“…More severe pain from a thoracotomy incision has been associated with higher incidences of pulmonary complications after thoracic surgery [1]. Furthermore, implementation of enhanced recovery pathways, more advanced perioperative monitoring technologies [21, 22], changes in surgical staff, as well as non-standardized algorithms for the detection of postoperative pulmonary complications in the historical cohort, could have led to a lower incidence of postoperative pulmonary complications in our study. Indeed, our overall rate of 7% for postoperative pulmonary complications was more consistent with recently reported rates of 8.5% for respiratory failure requiring re-intubation in non-cardiac surgery in surgical ICUs [23].…”

How to measure blood pressure using an arterial catheter: a systematic 5-step approach

“…Step 5: Checking the quality of the arterial blood pressure waveform-morphology and artifacts Optimal quality of the BP waveform is fundamental to correctly measure BP and estimate derived hemodynamic variables [15,46]. The performance characteristics of the measurement system are determined by the mass of fluid within the tubing system, the elasticity of the tubing system, and the friction between the fluid and the tubing system [6,47]. The performance characteristics are quantitatively described by the natural frequency of the measurement system (the frequency of pressure pulse oscillations within the system) and the damping coefficient (describing the decay of the oscillating waveform) [6,47].…”

“…There are several methods to measure BP: intermittent non-invasive measurements using oscillometry, continuous non-invasive measurements using methods such as the vascular unloading technique (also called "finger-cuff technology"), or continuous invasive measurements using an arterial catheter (also referred to as "direct" BP measurement) [5,6]. The choice of the BP monitoring method is important as it directly impacts clinical decision-making.…”

Impact of deep breathing on predictability of stroke volume variation in spontaneous breathing patients

“…Briefly, for the BP measurement, the Wesseling's Finapres method was developed. This system uses a physiological calibration algorithm for vascular unloading, inducing stepwise and intermittent BP changes, and simultaneously analyses the photoplethysmogram waveforms . The cuff attached to the finger is repeatedly inflated and deflated to keep the diameter of the finger artery constant, and BP values are calculated.…”