Intraosseous Catheterization

Chapter 62 Intraosseous Catheterization



Massimo Giunti, DVM, PhD, Cynthia M. Otto, DVM, PhD, DACVECC



KEY POINTS



• Intraosseous catheterization is an emergency procedure that allows access to the central circulation comparable to that achieved with a central venous line.

• Intraosseous catheterization is indicated when emergency vascular access is required and intravenous access can not be performed in a timely manner.

• Intraosseous catheterization is an easy, fast, and inexpensive technique that can be performed effectively in various species.

• Intraosseous infusion is contraindicated in recently fractured bones, those in which catheterization has been already attempted, and pneumatic bones of birds.

• The rate of complications for intraosseous infusion is extremely low, and osteomyelitis is the major risk.

• Blood samples obtained from intraosseous catheters can be analyzed for some hematologic, biochemical, and blood gas parameters in steady-state, low-flow conditions, and during the early phase of cardiopulmonary resuscitation.


INTRODUCTION


Rapid establishment of vascular access is crucial in critically ill patients, particularly those with life-threatening conditions. In animals with hemodynamic failure, peripheral vessels may constrict or collapse and grossly disappear. Finding and cannulating vessels is particularly challenging in small and neonatal patients. Attempts to catheterize a peripheral vein can be frustrating, time consuming, and unsuccessful even for the most skilled personnel. In pediatric prehospital and emergency department settings, peripheral intravenous access could not be obtained in 6% of patients and required over 10 minutes in 24%, with significantly prolonged times in children under 2 years of age.1


Compared with percutaneous peripheral vein catheterization, both surgical cutdown and central venous line placement increase the likelihood of successful circulatory access, but they require greater expertise and more time.1,2 Peripheral venous catheterization within 90 seconds is successful in only 18% of cases. The success rate increa-ses to 37% with subsequent percutaneous femoral vein catheterization.2


There are limited alternative routes for drug delivery in cases that require cardiovascular support but lack venous access. The endotracheal route is a last-resort option recommended by the American Heart Association for some resuscitation drugs during cardiac arrest in both adult and pediatric patients.3,4 This route obviously can not provide for fluid resuscitation, and even for commonly recommended drugs such as epinephrine the clinical effect is less predictable than when intravenous administration is used.5 Additionally, the dosage of intratracheal epinephrine has to be increased up to 10-fold.6 Furthermore, lower circulating epinephrine concentration, from endotracheal administration, could result in counterproductive β2-adrenergic stimulation, which leads to peripheral vasodilation, low diastolic aortic pressure, and decreased myocardial perfusion pressure.6


Two proposed but inadvisable routes of drug administration are the sublingual and intracardiac routes.7 Intracardiac injections are associated with risks (e.g., hemopericardium, coronary artery perforation, myocardial ischemia, arrhythmias) that exceed the benefits. Alternatives to intravenous access are reported,7 but they are indicated mainly for volume replacement in states of dehydration (subcutaneous or intraperitoneal infusion) and are not effective for hypovolemia.


Curiously, an unusual emergency vascular access, such as corpus cavernosum, was demonstrated to be fast and feasible for fluid resuscitation in dogs with severe hypovolemia, offering new therapeutic perspectives, even if limited to male dogs.8 In pediatric and adult patients, intraosseous access is now recommended as the first choice if intravenous access is unavailable.3,4 The intraosseous route is safe, practical, and reliable for fluid resuscitation, drug administration, and even blood sampling for analysis. This chapter focuses on what makes the intraosseous route suitable for fluid infusion and drug administration. The main indications, contraindications, complications, procedures, and future perspectives for intraosseous access in veterinary patients will be presented based on veterinary reports, human studies, and experimental animal models.



HISTORICAL PERSPECTIVES


The possibility of perfusing the tibia of the dog was demonstrated in 1922 by Drinker and colleagues, who were studying vascular physiology of the bone marrow.9 Starting from this scientific observation, the potential use of the intraosseous route for parenteral infusion of drugs and fluids was addressed by several studies in Europe and North America during the 1930s and 1940s.10-12 In rabbits, intraosseous infusions of whole blood and hypertonic glucose solutions rapidly corrected anemia and hypoglycemia, respectively.10 In dogs, intramedullary injection of citrated blood into the sternum effectively restored blood volume.11 Moreover, an injection of epinephrine into the marrow of the tibia resulted in a clinical response similar to that achieved by injection into the femoral vein.11


Intraosseous infusion was established as a reliable and safe technique for rapid, short-term access into the central circulation in adults and children when veins were inaccessible (e.g., peripheral circulatory failure, burns, and very young patients).11,12 However, with the introduction of plastic catheters for peripheral venous access during the late 1950s, intraosseous infusions fell into disuse.1,13 A renewed interest in the intraosseous procedure appeared during the 1980s because of its utility in hypotensive patients and efficacy for the administration of lifesaving drugs.14 The intraosseous route was recommended as an alternative emergency access in pediatric advanced life support for children under 6 years of age and, more recently, resuscitation guidelines extended its use to children of any age and even to adults.3,4



PHYSIOLOGY


The bone marrow is a semifluid blood-forming tissue enclosed in a nonexpandable bony case. This protective osseous coating prevents bone marrow vessels from collapsing during peripheral circulatory failure. A rich capillary network drives substances injected into the marrow to the large medullary venous channels and quickly through the nutrient and emissary veins to the central circulation.9-11


Several types of fluids (blood and blood components, colloids, crystalloids)11 and several drugs,15 administered through an intraosseous, a central, or a peripheral intravenous line, are equally effective in reaching the central circulation despite normotensive, hypotensive, or arrest conditions.14-16 Particularly during hemodynamic failure, intraosseous infusion of resuscitative fluids (e.g., hydroxyethyl starch) and drugs (e.g., sodium bicarbonate) seems to guarantee a higher magnitude of the peak effect and even a prolonged duration of action compared with peripheral venous administration.


Although intraosseously administered drugs reach peak effect more slowly14,15 because of a reduction in blood flow and an increase in vascular resistance in the bone marrow during systemic hypotension, this effect can be overcome partially by pressurized infusion, especially when using viscous fluids likes colloids, or by a fluid bolus following the injection of a drug into the intraosseous space.15 Mean intraosseous infusion flow rates of crystalloid solutions delivered under pressure (300 mm Hg) are limited to approximately 29 ml/min in puppies17 and 47 ml/min in foals. Thus rapid delivery (90 ml/kg within 30 minutes) of fluids during severe hypovolemia may not be possible in dogs that weigh more than 10 kg. However, intraosseous infusion of hyperoncotic, hypertonic, and even crystalloid solutions effectively reversed hypotension in several animal models of hemorrhagic shock (see Chapter 65, Shock Fluids and Fluid Challenge).18,19,22,23

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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Intraosseous Catheterization

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