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INTRODUCTION

FOCUS POINTS

  1. Arterial catheterization allows continuous blood pressure monitoring and facilitates arterial blood sampling.

  2. Knowledge of anatomy, advantages/disadvantages of different cannulation sites, and pitfalls during placement and interpretation of the arterial waveform are crucial.

  3. There are two approaches to arterial catheterization: through a technique in which a guidewire is used to thread a catheter into the vessel and through a direct puncture technique in which only one wall of the artery is punctured and the catheter is directly threaded into the vessel.

  4. Ultrasound can facilitate arterial catheterization and has been shown to increase the chance for first-attempt success and reduce mean attempts to success.

  5. Overdampening and underdampening of the transducer system cause incorrect blood pressure readings and should be evaluated with the “flush test.”

Monitoring of arterial blood pressure is often needed in critically ill adults and pediatric patients. Compared to adult anesthesia practice, arterial cannulation is performed less frequently in the pediatric population. As such, many procedures for which anesthesiologists would routinely perform arterial cannulations in adults are conducted in children with noninvasive blood pressure monitoring. In fact, arterial cannulation requires practice and becomes more challenging in younger and smaller size children. In this chapter, we will review the basic physiology, indications, contraindications, sites, and techniques for arterial cannulation.

BASIC PHYSIOLOGY

Invasive blood pressure monitoring via arterial catheterization is regarded as the “gold standard” for accurate hemodynamic assessment. The underlying physiology is based on pressure transduction via a fluid-filled catheter in the arterial blood vessel. Blood pressure fluctuations caused by cardiac ejections reach the arterial catheter, cause pulsations of the saline column that are transmitted to a diaphragm. The excursions of the diaphragm cause a change of resistance in the strain gauge transducer (Wheatstone bridge). This change in resistance is measured electronically, and processed, amplified, and converted into a visual display (waveforms).

Interpretation of the waveforms is presented below.

INDICATIONS

Arterial cannulation can theoretically be performed in any setting, but the need for monitoring equipment often limits the availability of arterial monitoring to the operating room, intensive care unit, or emergency department. While there are no absolute indications, most practitioners consider arterial cannulation if one or more of the following conditions apply:

  • Tight blood pressure control (eg, resection of a secreting pheochromocytoma)

  • Blood pressure monitoring during anticipated pharmacological or mechanical cardiovascular manipulation (eg, open heart surgery)

  • Blood pressure monitoring in the setting of non-pulsatile blood flow (cardiopulmonary bypass, left ventricular assist device)

  • Arterial blood sampling (eg, pH, gas, electrolyte, hemoglobin monitoring)

  • Inability to acquire reliable blood pressure measurements via a noninvasive route

  • Inability to use noninvasive blood pressure monitoring (eg, burns)

There is an increasing interest on ways to determine fluid responsiveness with changes in stroke volume, pulse pressure variation, and stroke volume variation. A large body of literature supports the use ...

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