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VASCULAR ACCESS
Artículo recibido: 04-04-2017
Artículo aprobado para publicación: 28-07-2017
ABSTRACT
Vascular access, arterial and venous, at peripheral and
more central sites is a core skill, yet is not always well
taught or in core training. Like many procedures, it
can be simple to learn the basics, but hazards await
inexperienced operators.
Key words: Vascular Access, central venous
access, arterial catheters, anatomy arteries veins,
complications.
GENERAL PRINCIPLES
Many insertion steps are common to all procedures: time
is needed to choose optimal devices and site dependent
on clinical need, length of treatment, and patient wishes.
Adequate explanation/consent is needed.
Asepsis is essential for all insertion and aftercare, because
of direct access to the circulation. This is under increasing
scrutiny (1). Prevention of needlestick injury is important
as access needles carry a significant inoculum of blood.
All but the smallest devices require Local Anesthesia (LA),
topical or injected. For central access, wide infiltration is
required (a minimum of 10-15mls for adults). Intravenous
sedation is helpful for anxious patients. Some patients (e.g.
children) will need general anaesthesia.
Cannulation is achieved by a number of techniques, including:
• Direct vision (e.g. superficial vessel or cut-down).
• Indirect vision (e.g. infrared devices).
• Palpation (arterial pulse, full vein).
• Landmark orientation (e.g. next to artery, clavicle).
• Ultrasound.
• X-ray (after contrast injection).
Needle entry is confirmed by backflow or aspiration of blood.
A catheter or guidewire can then be passed. Catheter posi-
tion is verified by aspiration/backflow of arterial or venous
blood, flushing the catheter, measurements of pressures,
ultrasound, X-ray and ECG guidance (2). Anchorage is needed
to avoid catheter dislodgement, with adhesive dressings
or sutures, or internal anchoring devices. Meticulous after-
care and observation is required to maintain safe effective
catheter function. This includes regular flushing, removal
before problems occur, and recognition and management of
complications (3,4).
Most devices utilise percutaneous techniques, but surgical
cut-down is still used in emergencies and small children.
Usage has diminished due to operative time and skills
needed, scars, potential greater damage to the cannulated
vessel, and higher risk of local infection (5).
Peripheral vein cannulation
This is a core technique and skill is required in challenging cases,
e.g. a small child, the very elderly with fragile veins, and when
all obvious veins have already blocked. It is not risk free (Table 1).
Discomfort is reduced by using the smallest feasible devices
and effective LA. Avoid insertion over joint flexures. Aids to
insertion are typically based on enhancing the size or visibility
of vessels. Traditionally these included transillumination and
local warming. High-resolution ultrasound aids procedures in
all ages (6). Newer devices utilize the differentia absorption
of infrared light, which penetrates deeper than visible light,
by blood compared with tissues to generate an image (7).
DR. ANDREW BODENHAM (1)
(1) Leeds General Infirmary. Consultant in Anaesthesia and Intensive Care Medicine. The leeds teaching Hospitals NHS Trust. United Kingdom
Email:
[REV. MED. CLIN. CONDES - 2017; 28(5) 701-712]