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Intraosseous Catheterization
CHAPTER 194 INTRAOSSEOUS CATHETERIZATION Massimo Giunti,
DVM, PhD • Cynthia
M. Otto,
DVM, PhD, DACVECC
KEY POINTS • Intraosseous catheterization is an emergency procedure that allows rapid 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 cannot be obtained 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 previously attempted, and the pneumatic bones of birds. • The rate of complications for intraosseous infusion is extremely low, and osteomyelitis is the primary 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.
Rapid establishment of vascular access is crucial in critically ill patients, particularly those with life-threatening conditions. Peripheral vessels often constrict or collapse and may grossly disappear in animals with hemodynamic failure. 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 human pediatric prehospital and emergency department settings, peripheral intravenous access could not be obtained in 6% of patients and required over 10 minutes to achieve in 24%, with significantly prolonged times in children younger than 2 years of age.1 Compared with percutaneous peripheral venous 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 increases to 37% with subsequent percutaneous femoral vein catheterization.2 There are limited alternative routes for drug delivery in animals 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 cannot 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 tenfold.6 Despite this dosage increase, lower circulating epinephrine concentration due to unpredictable absorption from the tracheal mucosa can result in counterproductive β2-adrenergic stimulation, leading 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., lung laceration, 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 (e.g., subcutaneous or intraperitoneal infusion) and are not effective for rapid treatment of hypovolemic patients. Curiously, an unusual type of emergency vascular access, via the 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 are 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 et al, who were studying the vascular physiology of the bone marrow.9 With this scientific observation as a starting point, 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 delivery of drugs and fluids into the central circulation in adults and children whose veins were inaccessible (e.g., because of peripheral circulatory failure, burns, or very young age).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 for emergency access in pediatric advanced life support for children younger than 6 years of age, and more recently, resuscitation guidelines extended its use to children of any age and even to adults.3,4 1009
1010
PART XXII • PROCEDURES
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 drugs15 reach the central circulation with equal effectiveness whether administered through an intraosseous, a central, or a peripheral intravenous line and whether delivered under normotensive, hypotensive, or arrest conditions.14-16 Particularly during hemodynamic failure, intraosseous infusion of resuscitative fluids (e.g., hydroxyethyl starch solutions) and drugs (e.g., sodium bicarbonate) seems to guarantee a higher magnitude of 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 partially overcome by using pressurized infusion, especially when viscous fluids likes colloids are given, or by administering 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 through a 20-gauge needle17 and 47 ml/min through a 14-gauge needle. Thus rapid delivery of fluids (90 ml/kg within 30 minutes) during severe hypovolemia may not be possible in dogs that weigh more than 15 kg, even when a 14-gauge needle is used. However, intraosseous infusion of hyperoncotic, hypertonic, and even crystalloid solutions effectively reversed hypotension in several animal models of hemorrhagic shock (see Chapter 60).18-21
INDICATIONS There are no studies documenting the incidence or impact of intraosseous catheterization in veterinary clinical practice. Most of the indications have been extrapolated from human experience and experimental animal models.7,12,17 The information obtained from pediatric patients, in whom the time required to complete an intraosseous catheterization can be less than 1 minute with over 70% to 80% success, may be particularly relevant to small and neonatal animals.18,19 Early implementation of the intraosseous route as an alternative to failed intravenous access is now widely accepted and is included in the guidelines for management of cardiac arrest in pediatric and adult human patients. These recommendations are applicable to veterinary patients as well, particularly small and neonatal animals whose veins can be difficult to visualize in health and tend to grossly disappear in shock states.22 Fluid resuscitation through an intraosseous catheter can usually restore vascular volume sufficiently to allow subsequent catheterization of a peripheral vein. Conditions such as peripheral vascular thrombosis, peripheral edema, status epilepticus, obesity, and burns may be additional indications for obtaining intraosseous access.13,18,19 Another advantage of intraosseous catheterization during emergency situations is the potential for blood sampling. Initial assessment of hematologic, biochemical, and acid-base status and subsequent monitoring of the therapeutic response are essential in critically ill patients. Blood sampling can be challenging, however, during cardiovascular collapse. The reliability of laboratory results obtained on blood collected from intraosseous lines has been investigated in both steady-state
conditions and circulatory failure. In normal animals, hemoglobin level, hematocrit, some biochemical parameters (levels of blood urea nitrogen, creatinine, total solids, albumin, bilirubin, sodium, chloride, calcium, phosphorus), and blood gases concentration are sufficiently comparable to those of peripheral or central venous blood to be of clinical value. Values obtained for potassium and glucose, however, need to be interpreted with caution.23,24 Acid-base values obtained from intraosseous samples in cardiopulmonary resuscitation (CPR) models reflect the mixed venous blood acid-base balance during the first 15 minutes of CPR, but beyond that time values can be influenced by local acidosis.20,21 In one CPR study, intraosseous and central venous blood biochemical and hemoglobin values remained similar for the first 30 minutes if the intraosseous site was not used for drug infusions.25
CONTRAINDICATIONS The only absolute contraindication to intraosseous catheterization is a fracture in the bone to be used. In cases of failed intraosseous catheter placement in which the cortex has been penetrated, the risk of fluid or drug extravasation is increased.13,19 To minimize risk, a second cannula of larger diameter should be placed through the same entry site or preferably a different bone should be used. Intraosseous infusions into pneumatic bones of birds are also contraindicated. Clearly, intraosseous catheters should not be placed through infected tissues. Sepsis and septic shock have been suggested as contraindications to the use of intraosseous lines; however, reported complication rates in septic children were low.1
METHODS The increased use of intraosseous catheterization during the last 15 to 20 years1,19 has been accompanied by the development of new medical equipment. Intraosseous catheters range from traditional manually placed hypodermic needles to dedicated catheters with automated delivery systems.19,25 The main requirements for any intraosseous delivery system are ease of handling, ability to reload, low expense, and adaptability to most conditions. The supplies necessary for an intraosseous catheterization kit are described in Box 194-1. Commercial disposable intraosseous infusion needles with a central stylet (Cook Critical Care, Bloomington, Ind.; Cardinal Health, McGaw Park, Ill.) are designed to penetrate the bony cortex, prevent occlusion of the cannula lumen, and establish rapid access to the marrow sinusoids and vascular system (Figure 194-1).19 However, an 18- to 30-gauge hypodermic needle is useful in neonates with soft cortical bone; an 18- to 22-gauge spinal needle is excellent in cats, small dogs, and birds; and a bone marrow or intraosseous infusion needle is essential in mature dogs.18 A bone injection gun is a spring-loaded, impact-driven intraosseous device developed for use in pediatric and adult humans. It propels the intraosseous cannula at high speed through skin, subcutaneous tissues, and bone cortex to a fixed depth. This automatic device was significantly faster than a standard Jamshidi bone marrow needle in obtaining intraosseous access in the proximal tibia of dogs.25 The high speed of insertion helps to minimize pain; however, local anesthesia is recommended in conscious patients.25 Other devices such as a drill for intraosseous access (EZ-IO, Vidacare, San Antonio, Tex.) (Figures 194-2 and 194-3) and a sternal intraosseous device (FAST1, Pyng Medical, Richmond, Canada) are now available.19 A feline cadaver study found that the EZ-IO system was faster and more likely to be successful than the bone injection gun and manual intraosseous needle placement, regardless of whether the tibia or humerus was used.26
CHAPTER 194 • Intraosseous Catheterization
BOX 194-1
Supplies Necessary for an Intraosseous Catheter Kit
• Topical antiseptic for skin preparation • Sterile gloves • Local anesthetic for the skin and periosteum • Scalpel blade for making a stab incision through the skin • Needles • Hypodermic (18 to 30 gauge) • Spinal (18 to 22 gauge) • Bone marrow or intraosseous infusion needles (Jamshidi/
Illinois, Cardinal Health, or Cook Critical Care) (see Figure 194-1) • EZ-IO device (Vidacare): recommended for more rapid access to the intraosseous space (see Figures 194-2 and 194-3) • Syringe for aspiration of bone marrow to confirm correct placement and potentially collect samples for hematologic or biochemical analysis • Heparinized saline solution (preservative free) • Fluid with administration set or catheter cap and pressure bag • Mechanism to secure the catheter: • Tape butterfly and suture material • Cyanoacrylates to secure suture directly to hub of needle • Commercial intraosseous catheter with flange • Bandaging material • Triple antibiotic ointment or appropriate antiseptic ointment or cream
The access site should be easily accessible and should not interfere with ongoing procedures such as CPR. The most commonly used sites are the flat medial surface of the proximal tibia (1 to 2 cm distal to the tibial tuberosity), the tibial tuberosity itself, and the trochanteric fossa of the femur (Figures 194-4 and 194-5). Alternative approachable points can be considered such as the wing of the ilium, the ischium, and the greater tubercle of the humerus.18,27 However, no studies in animal patients suggest any one site to be superior. Finally, the choice of a particular site depends on the experience and preference of the clinician, the anticipated duration of use, and the mobility of the patient. Placement in the trochanteric fossa of the femur seems to be well tolerated, allows mobility, and is generally
FIGURE 194-3 Insertion of EZ-IO needle into a bone.
FIGURE 194-1 Intraosseous infusion needle. (Courtesy Cardinal Health.)
FIGURE 194-4 Intraosseous needle placed in the trochanteric fossa of a sick kitten for fluid resuscitation.
FIGURE 194-2 EZ-IO battery-operated driver with intraosseous needle and stylet.
FIGURE 194-5 Radiograph of an intraosseous needle placed through the trochanteric fossa into the shaft of the femur in a ferret.
1011
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PART XXII • PROCEDURES
easy to perform.18 In obese or very edematous animals or those in status epilepticus, the tibia is probably more accessible.18 In humans, alternative sites include the sternum, radius, ulna, and calcaneus.19 Aseptic preparation of the site is required. The periosteum is highly innervated; therefore when the patient is alert or in stable condition, local infiltration with an anesthetic (e.g., 1% lidocaine) is recommended. A preemptive skin stab incision over the site of penetration of the catheter may prolong the life of the needle. For placement in the medial tibia, the needle must be directed into the bone slightly distally and away from the proximal growth plate. To prevent sciatic nerve injury during placement in the femur, the needle should be walked off the medial aspect of the greater trochanter into the trochanteric fossa, with the hip joint in a neutral and internally rotated position. Once the desired orientation of the needle is reached, firm pressure should be applied in clockwise and then counterclockwise rotation. This procedure normally generates a small depression that seats the needle in the bone; the pressure is then increased while the same rotation pattern is maintained, and the needle should proceed through the near cortex. A sudden loss of resistance indicates that the needle has penetrated the cortex. Before fluids or drugs are administered through an intraosseous catheter, verification of correct placement is required. One of the most frequently reported causes of failure of intraosseous catheterization is an error in identifying landmarks. A well-positioned catheter should be firmly seated in the bone and should move with the limb without being dislodged. Gentle aspiration should bring bone marrow into the syringe, although in older animals this may not always be possible. A bolus of heparinized saline solution should flow easily, and there should be no palpable accumulation of fluid in the subcutaneous tissue. If resistance is encountered, the needle can be rotated 90 to 180 degrees to move the beveled edge away from the inner cortex. The subcutaneous tissue must be observed for fluid extravasation. If extravasation is detected, the needle should be removed to prevent further complications and an alternative bone should be chosen for catheter placement. Once correct placement of the needle is verified, administration of fluids or drugs can be started by syringe or by use of a standard intravenous administration set. To maintain patency during intermittent usage, a catheter plug can be applied and the catheter flushed with heparinized saline solution. Initial infusion of fluids under pressure causes pain, lasting approximately 1 to 2 minutes, in conscious human patients. In humans, recommendations to minimize pain include withdrawal of a small volume of bone marrow and slow injection of 1% lidocaine over 60 seconds before the infusion is initiated. The intraosseous injection of lidocaine can be toxic, especially to cats. Neither the safety nor the efficacy of intraosseous lidocaine infusions to decrease the pain response to pressurized intraosseous infusions in small animals has been evaluated. To secure the needle properly, a tape butterfly can be wrapped around the hub and sutured to the skin or the periosteum. The suture may also be fixed to the hub of the needle with cyanoacrylate glue. Some intraosseous needles come with permanent butterflies for suturing. Covering of the area with antiseptic or antibiotic ointment is suggested, and when possible, application of a protective bandage can prevent damage to the needle. Intraosseous catheters require the same nursing care as intravenous catheters. In most cases, the intraosseous catheter is considered a temporary access line that should be replaced by an intravenous catheter as soon as possible. When prolonged intraosseous infusion is required, guidelines for intravenous catheter care should be followed. Although there are limited data, the risk of catheter-related complications is thought to be minimal for up to 72 hours with proper maintenance.18,26
COMPLICATIONS The documented complication rate associated with intraosseous infusions in humans and animals is low. The types of complications include infection, fat embolism, extravasation of fluids, nerve injury, compartment syndrome, and bone fractures.13,19 One of the most common concerns when performing intraosseous infusion is osteomyelitis. Use of proper sterile technique during placement reduces the risk of infection to 0.6% of cases, with potentially lower risk if the catheter is removed as soon as intravenous access is established or within 72 hours.1 Several studies have demonstrated that administration of fluids and drugs via the intraosseous route does not impair bone growth.28 Fat embolism can occur during intraosseous infusion; however, evidence for clinical significance is lacking. Although extravasation of fluids and compartment syndrome are unlikely with proper technique, they can be associated with major morbidity in humans. Improper catheter placement combined with the use of irritating or hypertonic fluids, high fluid rates, pressure infusion, and large infusion volumes can all predispose to extravasation of fluids and compartment syndrome.13,19 The latter does not appear to be a major issue in animals; however, if any infiltration is detected, the intraosseous infusion should be discontinued immediately. Also, it is imperative that no additional catheter be placed in the same bone. Generally intraosseous infusion of hypertonic solutions is considered effective and apparently safe. However, in one laboratory study of combined dehydration and hemorrhagic shock, piglets developed compartment syndrome and associated soft tissue and bone marrow necrosis 48 hours after intraosseous resuscitation with 7.5% hypertonic saline.29 Compartment syndrome has also been reported after 0.9% saline intraosseous resuscitation of a boy following cardiac arrest.30 The risk of compartment syndrome associated with intraosseous infusions is reported to be less than 1% in humans and is unknown in veterinary patients30; however, one study in dogs did demonstrate an increase in extravasation and tissue pressure associated with infusion of more than 350 ml (~23 ml/kg) of hypertonic contrast dye (Urografin 76; ~2000 mOsm/kg).31 Finally, appropriate insertion technique, asepsis, frequent monitoring of the intraosseous access site, and prompt removal of the needle once an intravenous line has been established help to reduce risk factors and complication rates.
REFERENCES 1. Rossetti VA, Thompson BM, Miller J, et al: Intraosseous infusion: an alternative route of pediatric intravascular access, Ann Emerg Med 14:885, 1985. 2. Kanter RK, Zimmerman JJ, Strauss RH, et al: Pediatric emergency intravenous access. Evaluation of a protocol, Am J Dis Child 140:132, 1986. 3. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science. Part 14: pediatric advanced life support, Circulation 112(Suppl 3):S876-908, 2010. 4. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science. Part 8: adult advanced cardiovascular life support, Circulation 122(Suppl 3):S729-767, 2010. 5. Niemann JT, Stratton SJ, Cruz B, et al: Endotracheal drug administration during out-of-hospital resuscitation: where are the survivors? Resuscitation 53:153, 2002. 6. Manisterski Y, Vaknin Z, Ben-Abraham R, et al: Endotracheal epinephrine: a call for larger doses, Anesth Analg 95:1037, 2002. 7. Orlowski JP: Emergency alternatives to intravenous access. Intraosseous, intratracheal, sublingual, and other-site drug administration, Pediatr Clin North Am 41:1183, 1994. 8. Stein M, Gray R: Corpus cavernosum as an emergency vascular access in dogs, Acad Radiol 2:1073, 1995.
9. Drinker CK, Drinker KR, Lund CC: The circulation in the mammal bone marrow, Am J Physiol 62:1, 1922. 10. Tocantins LM: Rapid absorption of substances injected into the bone marrow, Proc Soc Exp Biol Med 45:292, 1940. 11. Tocantins LM, O’Neill JF, Jones HW: Infusions of blood and other fluids via the bone marrow: application in pediatrics, JAMA 117:1229, 1941. 12. Heinild S, Sondergaard T, Tudvad F: Bone marrow infusion in childhood: experiences from a thousand infusions, J Pediatr 30:400, 1947. 13. LaRocco BG, Wang HE: Intraosseous infusion, Prehosp Emerg Care 7:280, 2003. 14. Spivey WH, Lathers CM, Malone DR, et al: Comparison of intraosseous, central, and peripheral routes of sodium bicarbonate administration during CPR in pigs, Ann Emerg Med 14:1135, 1985. 15. Orlowski JP, Porembka DT, Gallagher JM, et al: Comparison study of intraosseous, central intravenous, and peripheral intravenous infusions of emergency drugs, Am J Dis Child 144:112, 1990. 16. Warren DW, Kissoon N, Mattar A, et al: Pharmacokinetics from multiple intraosseous and peripheral intravenous site injections in normovolemic and hypovolemic pigs, Crit Care Med 22:838, 1994. 17. Hodge D III, Delgado-Paredes C, Fleisher G: Intraosseous infusion flow rates in hypovolemic “pediatric” dogs, Ann Emerg Med 16:305, 1987. 18. Otto CM, Kaufman MG, Crowe DT: Intraosseous infusion of fluids and therapeutics, Compend Contin Educ Pract Vet 11:42, 1989. 19. Weiser G, Hoffmann Y, Galbraith R, et al: Current advances in intraosseous infusion—a systematic review, Resuscitation 83:20-26, 2012. 20. Kissoon N, Idris A, Wenzel V, et al: Intraosseous and central venous blood acid-base relationship during cardiopulmonary resuscitation, Pediatr Emerg Care 13:250, 1997.
21. Johnson L, Kissoon N, Fiallos M, et al: Use of intraosseous blood to assess blood chemistries and hemoglobin during cardiopulmonary resuscitation with drug infusions, Crit Care Med 27:1147, 1999. 22. Aeschbacher G, Webb AI: Intraosseous injection during cardiopulmonary resuscitation in dogs, J Small Anim Pract 31:629, 1993. 23. Orlowski JP, Porembka DT, Gallagher JM, et al: The bone marrow as a source of laboratory studies, Ann Emerg Med 18:1348, 1989. 24. Dhein CR, Barbee DD: Use of bone marrow serum for biochemical analysis in healthy cats, J Am Vet Med Assoc 206:487, 1995. 25. Olsen D, Packer BE, Perrett J, et al: Evaluation of the bone injection gun as a method for intraosseous cannula placement for fluid therapy in adult dogs, Vet Surg 31:533, 2002. 26. Bukoski A, Winter M, Bandt C, et al: Comparison of three intraosseous access techniques in cats, J Vet Emerg Crit Care 20(4): 393-397, 2010. 27. Hughes D, Beal MW: Emergency vascular access, Vet Clin North Am Small Anim Pract 30:491, 2000. 28. Claudet I, Baunin C, Laporte-Turpin E, et al: Long-term effects on tibial growth after intraosseous infusion: a prospective, radiographic analysis, Pediatr Emerg Care 19:397, 2003. 29. Alam HB, Punzalan CM, Koustova E, et al: Hypertonic saline: intraosseous infusion causes myonecrosis in a dehydrated swine model of uncontrolled hemorrhagic shock, J Trauma 52:18, 2002. 30. Khan LAK, Anakwe RE, Murray A, et al: A severe complication following intraosseous infusion used during resuscitation of a child, Injury Extra 42(10):173-177, 2011. 31. Günal I, Köse N, Gürer D: Compartment syndrome after intraosseous infusion: An experimental study in dogs, J Pediatr Surg 31(11):1491-1493, 1996.
DVM, PhD • Cynthia
M. Otto,
DVM, PhD, DACVECC
KEY POINTS • Intraosseous catheterization is an emergency procedure that allows rapid 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 cannot be obtained 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 previously attempted, and the pneumatic bones of birds. • The rate of complications for intraosseous infusion is extremely low, and osteomyelitis is the primary 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.
Rapid establishment of vascular access is crucial in critically ill patients, particularly those with life-threatening conditions. Peripheral vessels often constrict or collapse and may grossly disappear in animals with hemodynamic failure. 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 human pediatric prehospital and emergency department settings, peripheral intravenous access could not be obtained in 6% of patients and required over 10 minutes to achieve in 24%, with significantly prolonged times in children younger than 2 years of age.1 Compared with percutaneous peripheral venous 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 increases to 37% with subsequent percutaneous femoral vein catheterization.2 There are limited alternative routes for drug delivery in animals 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 cannot 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 tenfold.6 Despite this dosage increase, lower circulating epinephrine concentration due to unpredictable absorption from the tracheal mucosa can result in counterproductive β2-adrenergic stimulation, leading 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., lung laceration, 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 (e.g., subcutaneous or intraperitoneal infusion) and are not effective for rapid treatment of hypovolemic patients. Curiously, an unusual type of emergency vascular access, via the 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 are 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 et al, who were studying the vascular physiology of the bone marrow.9 With this scientific observation as a starting point, 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 delivery of drugs and fluids into the central circulation in adults and children whose veins were inaccessible (e.g., because of peripheral circulatory failure, burns, or very young age).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 for emergency access in pediatric advanced life support for children younger than 6 years of age, and more recently, resuscitation guidelines extended its use to children of any age and even to adults.3,4 1009
1010
PART XXII • PROCEDURES
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 drugs15 reach the central circulation with equal effectiveness whether administered through an intraosseous, a central, or a peripheral intravenous line and whether delivered under normotensive, hypotensive, or arrest conditions.14-16 Particularly during hemodynamic failure, intraosseous infusion of resuscitative fluids (e.g., hydroxyethyl starch solutions) and drugs (e.g., sodium bicarbonate) seems to guarantee a higher magnitude of 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 partially overcome by using pressurized infusion, especially when viscous fluids likes colloids are given, or by administering 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 through a 20-gauge needle17 and 47 ml/min through a 14-gauge needle. Thus rapid delivery of fluids (90 ml/kg within 30 minutes) during severe hypovolemia may not be possible in dogs that weigh more than 15 kg, even when a 14-gauge needle is used. However, intraosseous infusion of hyperoncotic, hypertonic, and even crystalloid solutions effectively reversed hypotension in several animal models of hemorrhagic shock (see Chapter 60).18-21
INDICATIONS There are no studies documenting the incidence or impact of intraosseous catheterization in veterinary clinical practice. Most of the indications have been extrapolated from human experience and experimental animal models.7,12,17 The information obtained from pediatric patients, in whom the time required to complete an intraosseous catheterization can be less than 1 minute with over 70% to 80% success, may be particularly relevant to small and neonatal animals.18,19 Early implementation of the intraosseous route as an alternative to failed intravenous access is now widely accepted and is included in the guidelines for management of cardiac arrest in pediatric and adult human patients. These recommendations are applicable to veterinary patients as well, particularly small and neonatal animals whose veins can be difficult to visualize in health and tend to grossly disappear in shock states.22 Fluid resuscitation through an intraosseous catheter can usually restore vascular volume sufficiently to allow subsequent catheterization of a peripheral vein. Conditions such as peripheral vascular thrombosis, peripheral edema, status epilepticus, obesity, and burns may be additional indications for obtaining intraosseous access.13,18,19 Another advantage of intraosseous catheterization during emergency situations is the potential for blood sampling. Initial assessment of hematologic, biochemical, and acid-base status and subsequent monitoring of the therapeutic response are essential in critically ill patients. Blood sampling can be challenging, however, during cardiovascular collapse. The reliability of laboratory results obtained on blood collected from intraosseous lines has been investigated in both steady-state
conditions and circulatory failure. In normal animals, hemoglobin level, hematocrit, some biochemical parameters (levels of blood urea nitrogen, creatinine, total solids, albumin, bilirubin, sodium, chloride, calcium, phosphorus), and blood gases concentration are sufficiently comparable to those of peripheral or central venous blood to be of clinical value. Values obtained for potassium and glucose, however, need to be interpreted with caution.23,24 Acid-base values obtained from intraosseous samples in cardiopulmonary resuscitation (CPR) models reflect the mixed venous blood acid-base balance during the first 15 minutes of CPR, but beyond that time values can be influenced by local acidosis.20,21 In one CPR study, intraosseous and central venous blood biochemical and hemoglobin values remained similar for the first 30 minutes if the intraosseous site was not used for drug infusions.25
CONTRAINDICATIONS The only absolute contraindication to intraosseous catheterization is a fracture in the bone to be used. In cases of failed intraosseous catheter placement in which the cortex has been penetrated, the risk of fluid or drug extravasation is increased.13,19 To minimize risk, a second cannula of larger diameter should be placed through the same entry site or preferably a different bone should be used. Intraosseous infusions into pneumatic bones of birds are also contraindicated. Clearly, intraosseous catheters should not be placed through infected tissues. Sepsis and septic shock have been suggested as contraindications to the use of intraosseous lines; however, reported complication rates in septic children were low.1
METHODS The increased use of intraosseous catheterization during the last 15 to 20 years1,19 has been accompanied by the development of new medical equipment. Intraosseous catheters range from traditional manually placed hypodermic needles to dedicated catheters with automated delivery systems.19,25 The main requirements for any intraosseous delivery system are ease of handling, ability to reload, low expense, and adaptability to most conditions. The supplies necessary for an intraosseous catheterization kit are described in Box 194-1. Commercial disposable intraosseous infusion needles with a central stylet (Cook Critical Care, Bloomington, Ind.; Cardinal Health, McGaw Park, Ill.) are designed to penetrate the bony cortex, prevent occlusion of the cannula lumen, and establish rapid access to the marrow sinusoids and vascular system (Figure 194-1).19 However, an 18- to 30-gauge hypodermic needle is useful in neonates with soft cortical bone; an 18- to 22-gauge spinal needle is excellent in cats, small dogs, and birds; and a bone marrow or intraosseous infusion needle is essential in mature dogs.18 A bone injection gun is a spring-loaded, impact-driven intraosseous device developed for use in pediatric and adult humans. It propels the intraosseous cannula at high speed through skin, subcutaneous tissues, and bone cortex to a fixed depth. This automatic device was significantly faster than a standard Jamshidi bone marrow needle in obtaining intraosseous access in the proximal tibia of dogs.25 The high speed of insertion helps to minimize pain; however, local anesthesia is recommended in conscious patients.25 Other devices such as a drill for intraosseous access (EZ-IO, Vidacare, San Antonio, Tex.) (Figures 194-2 and 194-3) and a sternal intraosseous device (FAST1, Pyng Medical, Richmond, Canada) are now available.19 A feline cadaver study found that the EZ-IO system was faster and more likely to be successful than the bone injection gun and manual intraosseous needle placement, regardless of whether the tibia or humerus was used.26
CHAPTER 194 • Intraosseous Catheterization
BOX 194-1
Supplies Necessary for an Intraosseous Catheter Kit
• Topical antiseptic for skin preparation • Sterile gloves • Local anesthetic for the skin and periosteum • Scalpel blade for making a stab incision through the skin • Needles • Hypodermic (18 to 30 gauge) • Spinal (18 to 22 gauge) • Bone marrow or intraosseous infusion needles (Jamshidi/
Illinois, Cardinal Health, or Cook Critical Care) (see Figure 194-1) • EZ-IO device (Vidacare): recommended for more rapid access to the intraosseous space (see Figures 194-2 and 194-3) • Syringe for aspiration of bone marrow to confirm correct placement and potentially collect samples for hematologic or biochemical analysis • Heparinized saline solution (preservative free) • Fluid with administration set or catheter cap and pressure bag • Mechanism to secure the catheter: • Tape butterfly and suture material • Cyanoacrylates to secure suture directly to hub of needle • Commercial intraosseous catheter with flange • Bandaging material • Triple antibiotic ointment or appropriate antiseptic ointment or cream
The access site should be easily accessible and should not interfere with ongoing procedures such as CPR. The most commonly used sites are the flat medial surface of the proximal tibia (1 to 2 cm distal to the tibial tuberosity), the tibial tuberosity itself, and the trochanteric fossa of the femur (Figures 194-4 and 194-5). Alternative approachable points can be considered such as the wing of the ilium, the ischium, and the greater tubercle of the humerus.18,27 However, no studies in animal patients suggest any one site to be superior. Finally, the choice of a particular site depends on the experience and preference of the clinician, the anticipated duration of use, and the mobility of the patient. Placement in the trochanteric fossa of the femur seems to be well tolerated, allows mobility, and is generally
FIGURE 194-3 Insertion of EZ-IO needle into a bone.
FIGURE 194-1 Intraosseous infusion needle. (Courtesy Cardinal Health.)
FIGURE 194-4 Intraosseous needle placed in the trochanteric fossa of a sick kitten for fluid resuscitation.
FIGURE 194-2 EZ-IO battery-operated driver with intraosseous needle and stylet.
FIGURE 194-5 Radiograph of an intraosseous needle placed through the trochanteric fossa into the shaft of the femur in a ferret.
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PART XXII • PROCEDURES
easy to perform.18 In obese or very edematous animals or those in status epilepticus, the tibia is probably more accessible.18 In humans, alternative sites include the sternum, radius, ulna, and calcaneus.19 Aseptic preparation of the site is required. The periosteum is highly innervated; therefore when the patient is alert or in stable condition, local infiltration with an anesthetic (e.g., 1% lidocaine) is recommended. A preemptive skin stab incision over the site of penetration of the catheter may prolong the life of the needle. For placement in the medial tibia, the needle must be directed into the bone slightly distally and away from the proximal growth plate. To prevent sciatic nerve injury during placement in the femur, the needle should be walked off the medial aspect of the greater trochanter into the trochanteric fossa, with the hip joint in a neutral and internally rotated position. Once the desired orientation of the needle is reached, firm pressure should be applied in clockwise and then counterclockwise rotation. This procedure normally generates a small depression that seats the needle in the bone; the pressure is then increased while the same rotation pattern is maintained, and the needle should proceed through the near cortex. A sudden loss of resistance indicates that the needle has penetrated the cortex. Before fluids or drugs are administered through an intraosseous catheter, verification of correct placement is required. One of the most frequently reported causes of failure of intraosseous catheterization is an error in identifying landmarks. A well-positioned catheter should be firmly seated in the bone and should move with the limb without being dislodged. Gentle aspiration should bring bone marrow into the syringe, although in older animals this may not always be possible. A bolus of heparinized saline solution should flow easily, and there should be no palpable accumulation of fluid in the subcutaneous tissue. If resistance is encountered, the needle can be rotated 90 to 180 degrees to move the beveled edge away from the inner cortex. The subcutaneous tissue must be observed for fluid extravasation. If extravasation is detected, the needle should be removed to prevent further complications and an alternative bone should be chosen for catheter placement. Once correct placement of the needle is verified, administration of fluids or drugs can be started by syringe or by use of a standard intravenous administration set. To maintain patency during intermittent usage, a catheter plug can be applied and the catheter flushed with heparinized saline solution. Initial infusion of fluids under pressure causes pain, lasting approximately 1 to 2 minutes, in conscious human patients. In humans, recommendations to minimize pain include withdrawal of a small volume of bone marrow and slow injection of 1% lidocaine over 60 seconds before the infusion is initiated. The intraosseous injection of lidocaine can be toxic, especially to cats. Neither the safety nor the efficacy of intraosseous lidocaine infusions to decrease the pain response to pressurized intraosseous infusions in small animals has been evaluated. To secure the needle properly, a tape butterfly can be wrapped around the hub and sutured to the skin or the periosteum. The suture may also be fixed to the hub of the needle with cyanoacrylate glue. Some intraosseous needles come with permanent butterflies for suturing. Covering of the area with antiseptic or antibiotic ointment is suggested, and when possible, application of a protective bandage can prevent damage to the needle. Intraosseous catheters require the same nursing care as intravenous catheters. In most cases, the intraosseous catheter is considered a temporary access line that should be replaced by an intravenous catheter as soon as possible. When prolonged intraosseous infusion is required, guidelines for intravenous catheter care should be followed. Although there are limited data, the risk of catheter-related complications is thought to be minimal for up to 72 hours with proper maintenance.18,26
COMPLICATIONS The documented complication rate associated with intraosseous infusions in humans and animals is low. The types of complications include infection, fat embolism, extravasation of fluids, nerve injury, compartment syndrome, and bone fractures.13,19 One of the most common concerns when performing intraosseous infusion is osteomyelitis. Use of proper sterile technique during placement reduces the risk of infection to 0.6% of cases, with potentially lower risk if the catheter is removed as soon as intravenous access is established or within 72 hours.1 Several studies have demonstrated that administration of fluids and drugs via the intraosseous route does not impair bone growth.28 Fat embolism can occur during intraosseous infusion; however, evidence for clinical significance is lacking. Although extravasation of fluids and compartment syndrome are unlikely with proper technique, they can be associated with major morbidity in humans. Improper catheter placement combined with the use of irritating or hypertonic fluids, high fluid rates, pressure infusion, and large infusion volumes can all predispose to extravasation of fluids and compartment syndrome.13,19 The latter does not appear to be a major issue in animals; however, if any infiltration is detected, the intraosseous infusion should be discontinued immediately. Also, it is imperative that no additional catheter be placed in the same bone. Generally intraosseous infusion of hypertonic solutions is considered effective and apparently safe. However, in one laboratory study of combined dehydration and hemorrhagic shock, piglets developed compartment syndrome and associated soft tissue and bone marrow necrosis 48 hours after intraosseous resuscitation with 7.5% hypertonic saline.29 Compartment syndrome has also been reported after 0.9% saline intraosseous resuscitation of a boy following cardiac arrest.30 The risk of compartment syndrome associated with intraosseous infusions is reported to be less than 1% in humans and is unknown in veterinary patients30; however, one study in dogs did demonstrate an increase in extravasation and tissue pressure associated with infusion of more than 350 ml (~23 ml/kg) of hypertonic contrast dye (Urografin 76; ~2000 mOsm/kg).31 Finally, appropriate insertion technique, asepsis, frequent monitoring of the intraosseous access site, and prompt removal of the needle once an intravenous line has been established help to reduce risk factors and complication rates.
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9. Drinker CK, Drinker KR, Lund CC: The circulation in the mammal bone marrow, Am J Physiol 62:1, 1922. 10. Tocantins LM: Rapid absorption of substances injected into the bone marrow, Proc Soc Exp Biol Med 45:292, 1940. 11. Tocantins LM, O’Neill JF, Jones HW: Infusions of blood and other fluids via the bone marrow: application in pediatrics, JAMA 117:1229, 1941. 12. Heinild S, Sondergaard T, Tudvad F: Bone marrow infusion in childhood: experiences from a thousand infusions, J Pediatr 30:400, 1947. 13. LaRocco BG, Wang HE: Intraosseous infusion, Prehosp Emerg Care 7:280, 2003. 14. Spivey WH, Lathers CM, Malone DR, et al: Comparison of intraosseous, central, and peripheral routes of sodium bicarbonate administration during CPR in pigs, Ann Emerg Med 14:1135, 1985. 15. Orlowski JP, Porembka DT, Gallagher JM, et al: Comparison study of intraosseous, central intravenous, and peripheral intravenous infusions of emergency drugs, Am J Dis Child 144:112, 1990. 16. Warren DW, Kissoon N, Mattar A, et al: Pharmacokinetics from multiple intraosseous and peripheral intravenous site injections in normovolemic and hypovolemic pigs, Crit Care Med 22:838, 1994. 17. Hodge D III, Delgado-Paredes C, Fleisher G: Intraosseous infusion flow rates in hypovolemic “pediatric” dogs, Ann Emerg Med 16:305, 1987. 18. Otto CM, Kaufman MG, Crowe DT: Intraosseous infusion of fluids and therapeutics, Compend Contin Educ Pract Vet 11:42, 1989. 19. Weiser G, Hoffmann Y, Galbraith R, et al: Current advances in intraosseous infusion—a systematic review, Resuscitation 83:20-26, 2012. 20. Kissoon N, Idris A, Wenzel V, et al: Intraosseous and central venous blood acid-base relationship during cardiopulmonary resuscitation, Pediatr Emerg Care 13:250, 1997.
21. Johnson L, Kissoon N, Fiallos M, et al: Use of intraosseous blood to assess blood chemistries and hemoglobin during cardiopulmonary resuscitation with drug infusions, Crit Care Med 27:1147, 1999. 22. Aeschbacher G, Webb AI: Intraosseous injection during cardiopulmonary resuscitation in dogs, J Small Anim Pract 31:629, 1993. 23. Orlowski JP, Porembka DT, Gallagher JM, et al: The bone marrow as a source of laboratory studies, Ann Emerg Med 18:1348, 1989. 24. Dhein CR, Barbee DD: Use of bone marrow serum for biochemical analysis in healthy cats, J Am Vet Med Assoc 206:487, 1995. 25. Olsen D, Packer BE, Perrett J, et al: Evaluation of the bone injection gun as a method for intraosseous cannula placement for fluid therapy in adult dogs, Vet Surg 31:533, 2002. 26. Bukoski A, Winter M, Bandt C, et al: Comparison of three intraosseous access techniques in cats, J Vet Emerg Crit Care 20(4): 393-397, 2010. 27. Hughes D, Beal MW: Emergency vascular access, Vet Clin North Am Small Anim Pract 30:491, 2000. 28. Claudet I, Baunin C, Laporte-Turpin E, et al: Long-term effects on tibial growth after intraosseous infusion: a prospective, radiographic analysis, Pediatr Emerg Care 19:397, 2003. 29. Alam HB, Punzalan CM, Koustova E, et al: Hypertonic saline: intraosseous infusion causes myonecrosis in a dehydrated swine model of uncontrolled hemorrhagic shock, J Trauma 52:18, 2002. 30. Khan LAK, Anakwe RE, Murray A, et al: A severe complication following intraosseous infusion used during resuscitation of a child, Injury Extra 42(10):173-177, 2011. 31. Günal I, Köse N, Gürer D: Compartment syndrome after intraosseous infusion: An experimental study in dogs, J Pediatr Surg 31(11):1491-1493, 1996.