RESPIRATORY SERVICES PANDEMIC

PLANNING

ARTERIAL PUNCTURES AND

SAMPLING

ARTERIAL PUNCTURE

INDICATIONS, CONTRAINDICATIONS AND HAZARDS1. INDICATIONS:

It is essential to obtain arterial samples for accurate blood gas analysis since peripheral venous samples may vary in relation to local tissue metabolism, and capillary samples are prone to venous admixture and air contamination. Accurate measurement of blood gases and acid-base balance can be of great value, diagnostically and/or therapeutically in the following situations:

A. a patient who, by clinical assessment, is believed to have an alteration in acid-base balance, ventilation or oxygenation i.e.: emphysema, drug overdose, cardiac arrest, and diabetic coma

B. a patient who develops unexpected tachypnea, dyspnea, restlessness, anxiety, irritability, drowsiness or confusion

C. to establish baseline values in a patient with chronic lung disease and to monitor improvement/deterioration

D. a patient with chronic lung disease prior to surgery

E. a patient whose clinical picture appears to be deteriorating

F. a patient on a ventilator

G. to evaluate changes in the delivery of specific respiratory care (i.e. ventilation, oxygenation, and medication)

2. CONTRAINDICATIONS:

The need for accurate measurement of blood gases and acid-base balance in a given patient situation may outweigh a contraindication, however, the following are considered to be relative contraindications to arterial puncture (unless otherwise indicated):

A. bilateral negative modified Allen’s test

B. a patient on anticoagulant or thrombolytic medication (see next section)

C. a patient with a coagulation disorder (i.e. hemophilia)

D. a patient with severe hypotension

E. a patient with deformities of the puncture site area (i.e. arthritis of the hands and wrists, congenital arm or hip deformity)

F. femoral artery grafts are an absolute contraindication to femoral puncture

G. a patient with Raynaud's Disease (a peripheral vascular disease characterized by a intermittent attacks of pallor or cyanosis of the digits)

H. a patient with fibrosed arteries

I. a patient with large hematoma of the puncture site area

J. a patient who refuses to cooperate

NOTE: If you are concerned about a possible contraindication to arterial puncture, discuss this matter with the patient's physician

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3. HAZARDS:

A. To Patient:Arterial puncture is an invasive technique, therefore, all of the following are potential hazards:

a) hematoma, hemorrhage

b) infection

c) thrombosis

d) arterial spasm

e) laceration of blood vessels or nerves

B. To Staff:Blood borne infections

NOTE: All blood should be treated as biohazardous material and handled in accordance with Standard Calgary Health Region Infection Prevention Precautions.

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HEMOSTATIC CONSIDERATIONSPrior to attempting any invasive blood procurement procedure the patient must be assessed for the presence of a coagulopathy (be it pathologic, idiopathic, therapeutic, or iatrogenic). In order to recognize a disorder of hemostasis one must thoroughly evaluate various aspects of each patient. In this section we will discuss the major tests used to assess hemostasis, identify and classify various anticoagulation and thrombolytic medications, and briefly describe some of the causes of pathologic coagulopathy.

1. LABORATORY ASSESSMENT OF HEMOSTASIS:

A. PRIMARY HEMOSTASIS:

i) Platelet Count

- Normal value 150,000 – 300,000/μL- High risk of spontaneous bleeding with count <10,000/μL- Decreased platelet count – Thrombocytopenia- Causes of Thrombocytopenia (see section 3 on disorders of hemostasis).

B. SECONDARY HEMOSTASIS:

i) INR (International Normalized Ratio). Assess extrinsic and common coagulation pathways.

- Normal value 0.9 – 1.1

- Critical value >6

- Causes of high INR include; Warfarin, liver disease & some cephalosporin antibiotics

ii) Activated Partial Thromboplastin Time (aPTT). Assess intrinsic & common coagulation pathways.

- Normal value 23.0 – 34.0 seconds

- Critical value >120 seconds

- Causes of prolonged PTT include; Heparin admin. & various clotting factor deficiencies

iii) Fibrinogen (factor I in the coagulation cascade)

- Normal value 1.6 – 4.1 g/L

- Critical low value <0.6 g/L

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2. MEDICATIONS DIRECTLY AFFECTING HEMOSTASIS:

Medications that directly affect hemostasis generally fall into three categories; Anticoagulants, Thrombolytics, and Platelet Aggregation Inhibitors. The following are some medications you may see here in the Calgary Health Region. NOTE: This section is for general information purposes and will not be tested in detail.

A. ANTICOAGULANTS:i) Heparins, Standard:

a) Heparin sodium

ii) Heparins, Low Molecular Weight (LMWH):

a) Fragmin (dalteparin sodium)b) Innohep (tinzaparin)c) Lovenox (enoxaparin sodium)

iii) Heparinoids:

a) Orgaran (danaparoid sodium)

iv) Vitamin K Antagonists:

a) Coumadin (warfarin sodium)b) Sintrom (nicoumalone)

v) Various Anticoagulants:

a) Refludan (lepirudin)

B. THROMBOLYTICS:

i) Streptase (streptokinase)

ii) Retavase (reteplase)

iii) Activase rt-PA (alteplase)

C. PLATELET AGGREGATION INHIBITORS:

i) Aggrenox (dipyridamole/ASA)

ii) Plavix (clopidogrel bisulfate)

iii) Integrilin (eptifibatide)

iv) Aggrastat (tibrofiban hydrochloride)

v) Reopro (abciximab)

vi) Ticlid (ticlopidine hydrochloride)

vii) ASA (acetylsalicylic acid)

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3. DISORDERS OF HEMOSTASIS:

Platelet quality and quantity is a major consideration in assessing hemostasis. Various factors that can cause platelet abnormalities will be outlined next. NOTE: This section is for general information purposes and will not be tested in detail.

A. PATHOLOGIC MECHANISMS OF ACQUIRED THROMBOCYTOPENIA (PLATELET QUANTITY):

i) Decreased platelet production:

- Bone marrow infiltration (tumor or infection)- Aplastic anemia- Viral infections (measles)- Various drugs (thiazides, estrogens, ethanol, & various chemotherapeutic agents)- Radiation- Vitamin B12 and/or folate deficiency

ii) Increased platelet destruction:

- Idiopathic thrombocytopenic purpura (ITP)- Thrombotic thrombocytopenic purpura (TTP)- Hemolytic uremic syndrome (HUS)- Disseminated intravascular coagulation (DIC)- Viral infections (HIV, mumps, varicella, EBV)- Drugs (heparin, protamine)

iii) Splenic sequestration:

- Hypersplenism- Hypothermia

iv) Platelet loss:

- Excessive hemorrhage- Hemodialysis- Extracorporeal circulation

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B. CONDITIONS ASSOCIATED WITH QUALITATIVE PLATELET ABNORMALITIES:

i) Uremia

ii) Liver disease

iii) DIC

iv) Drugs:

- Aspirin, NSAIDs- Heparin & thrombolytics- Penicillins and cephalosporins- Prostaglandins- Calcium channel blockers (Cardizem, Verapamil, Adalat, etc.)- Propanolol- Nitroprusside- Nitroglycerin- Tricyclic antidepressants (amitriptyline (Elavil), desipramine, doxepin, etc.)- Antihistamines- Chemotherapeutics

v) Antiplatelet antibodies:

- ITP- Systemic lupus erythematosus (SLE)

vi) Cardiopulmonary bypass

vii) Myeloproliferative disorders:

- Polycythemia vera (PCV)- Chronic myelogenous leukemia (CML)

viii) Multiple myeloma

ix) Preleukemias:

- Acute lymphocytic leukemia (ALL)- Acute myelogenous leukemia (AML)

x) Hemophilia, Von Willebrand disease, and other clotting factor disorders

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ADVANTAGES AND DISADVANTAGES OF THERADIAL ARTERY SITE

A. ADVANTAGES:

1. The deep and superficial palmar arches are supplied with blood from both the radial and ulnar arteries, therefore, if the radial artery becomes obstructed collateral blood flow to the hand should be available via the ulnar artery.

2. The radial artery at the wrist is superficial, therefore relatively easy to palpate, stabilize and puncture.

3. The wrist is generally easily accessible.

4. The radial artery typically does not have any major nerves in close proximity (at the wrist), therefore as long as puncture of the bony periosteum is avoided, the patient should only feel discomfort similar to that of a venous puncture.

B. RELATIVE DISADVANTAGES:

1. The radial artery is more peripheral than the femoral artery therefore, somewhat more likely to go into spasm. However, as long as ulnar flow is present this is not a problem (assessed during the modified Allen’s test).

2. There is a radial vein located on each side of the radial artery therefore it is possible to inadvertently draw a venous sample. However, these veins are of smaller diameter than the artery and normally have much lower pressure.

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ANATOMY FOR RADIAL ARTERIAL PUNCTUREThe optimal site for radial arterial puncture is in the natural tunnel between the styloid process of the radial bone and the flexor carpi radialis tendon, approximately 1 to 2 cm proximal to the wrist crease (Figure 3). The site is considered optimal due to the isolation of the artery from other structures and its proximity to the skin surface.

ARTERIAL SUPPLY OF THE ARM, WRIST & HAND

Arterial supply of the right arm is via the brachiocephalic artery from the arch of the aorta to the right subclavian artery. Arterial supply to the left arm is via the left subclavian artery, which arises directly from the arch of the aorta. The subclavian artery, on each side, passes between the clavicle and first rib to become the axillary artery as it enters the axilla and the brachial artery as it leaves the axilla. At the elbow the brachial artery divides into the radial and ulnar arteries.

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The radial artery courses along the lateral side of the arm (thumb side) over the radius while the ulnar artery courses along the medial side of the arm over the ulna (Figure 6 & 7). The radial and ulnar arteries meet in the palm of the hand at the superficial and deep palmar arches (Figure 8 & 9). From the palmar arches the various digits of the hand are supplied. Thus, a collateral blood supply system to the hand is provided.

NERVE SUPPLY OF THE FOREARM

Only the three nerves which lie closest to the radial artery will be discussed, and none of these lies directly alongside the artery (Figure 10 & 14).

A. Lateral Cutaneous Nerve - A continuation of the musculocutaneous nerve. It has a general sensory function for skin over the radial (lateral) side of the forearm ( Figure 11). At the wrist it passes over the brachioradialis tendon.

B. Median Nerve - Supplies motor function to most flexor muscles of the forearm and lateral three digits of the hand. It also supplies sensory function to the anterior (palmar) aspects of the lateral four digits of the hand. It is separated from the radial artery by the flexor carpi radialis tendon and the deeper flexor pollicis longus tendon.

C. Radial Nerve, Superficial Branch - The radial nerve descends in the back of the arm and forearm ultimately distributed, for motor function, to extensor muscles on back of arm, forearm and hand and sensory function to skin of the same region. The Superficial Branch of the radial nerve is primarily involved in sensory supply to the lateral three digits. It is separated from the radial artery by the brachioradialis tendon and travels along the lateral side of the radius in the area of the wrist.

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SKELETAL STRUCTURES OF THE ARM

The humerus, the large bone of the arm articulates with the radius and ulna at the elbow joint (Figure 13). The two bones of the forearm are the radius laterally (thumb side) and the ulna medially. The distal ends of the radius and ulna articulate with the carpal bones to form the wrist joint. The lateral bony prominence of the wrist is the styloid process of the radial bone. Distal to the carpal bones are the metacarpal bones (long bones of the palm) and finally the phalanges (long bones of the digits).

FIGURE 13

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styloid process

MODIFIED ALLEN'S TESTPURPOSE, PROCEDURE AND IMPLICATIONS

PURPOSE: The Modified Allen's Test must be performed prior to radial artery puncture to ensure that the ulnar artery is capable of supplying adequate blood flow to the superficial and deep palmar arches of the hand if the radial artery should become obstructed.

PROCEDURE:

1. Briefly explain procedure to patient and ascertain which is his non-dominant hand as this is the arm of choice for radial artery puncture if no other contraindicating circumstances.

2. Locate patient's radial and ulnar artery pulses at wrist using your index and middle fingers of each hand.

3. Have the patient tightly close the hand and squeeze for a few seconds to blanch the palm of the hand by forcing as much blood from the hand as possible (creating a white blotchy condition of the palm). In a patient who is unconscious or unable to cooperate, have another person elevate the patient's hand above the level of the heart and then squeeze the hand until blanching occurs.

4. Using your thumbs for support behind the patient's wrist, press down on the patient's radial and ulnar arteries with your fingers, tightly enough to occlude circulation to the patient's hand, while patient keeps the hand closed (Figure 15-a).

5. Have the patient relax, but not fully extend, the hand (Figure15-b).6. Release pressure from the ulnar artery, while maintaining pressure on the radial artery, and

observe the patient's hand. It should become flushed within 15 seconds if ulnar artery blood flow is adequate (Figure 15-c).

IMPLICATIONS:

The flushing of the patient's hand within 15 seconds while pressure is still maintained on the radial artery constitutes a positive Modified Allen's Test. Under these circumstances it may be assumed that if arterial puncture should result in obstruction of the radial artery, this will not result in diminution of blood supply to the hand. If the ulnar artery does not adequately supply the entire hand (a negative test) the radial artery should not be used as a puncture site. Perform Allen's Test on the patient's other arm before considering femoral puncture.

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FIGURE 15PROCEDURE FOR RADIAL ARTERY PUNCTURE

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NOTE: For additional information review the policy and procedure on arterial punctures.

1. Check for order, verify oxygen levels/ventilator settings, patient identity and contraindications.

2. Wash hands thoroughly and don gloves.

3. Assemble necessary equipment. Arterial blood sampling kit:

- 3 cc heparinized syringe (balanced)- 1” needle (23 gauge)- One rubber cube- One rubber cap

Alcohol swab 1 – 2 X 2 sterile gauze pad Gloves Biohazard Bag Cup of ice slurry (optional)

4. Take equipment to patient's bedside.

5. Examine radial sites for recent punctures and/or bruising. Choose the site with the least amount of bruising/punctures.

6. Explain the modified Allen’s Test and the arterial puncture procedure to patient to ensure cooperation and understanding. Explanations should be simple, concise and emphasize the value of the information obtained by the analysis. Ensure that the patient understands the importance of not moving his arm during the puncture procedure.

7. Perform Modified Allen’s Test on the best site. If the test is negative (no collateral circulation) assess the other wrist. If both sides are negative then consult the physician to approve radial puncture or to choose an alternate site.

8. If the modified Allen’s test is positive (meaning good collateral circulation), position the patient by externally rotating the arm and dorsiflex the wrist 45o over a towel. Have an assistant stabilize patient’s wrist, if necessary.

9. With an alcohol swab (of betadine swab when appropriate) cleanse the site and gloved fingers used to palpate (do not contaminate fingers by touching areas that have not been cleansed or by touching other equipment/supplies).

10. Allow site to dry for at least 30 seconds.

11. Using your cleansed index and middle fingers, palpate the radial artery in the natural tunnel between the styloid process of the radial bone and the flexor carpi radialis tendon, approximately 1-2 cm proximal to the wrist crease. Locate the area of maximal pulsation.

10. Check needle tip for absence of machining errors (burrs). Hold syringe at the base, enter site with the needle bevel up and at a 30-45o angle at a safe distance from the palpating fingers. The angle between the needle and the artery should be small to make the hole

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through the arterial wall oblique (so circular smooth muscle fibers can better seal the hole when the needle is withdrawn).

FIGURE 16

NOTE: As soon as the needle enters the artery, blood should flow freely into the syringe and a pulsation should be visualized. Unless the patient's arterial pressure is very low, lack of pulsatile flow indicates the probability of the needle being in a vein.

11. If a radial artery cannot be located either:

1) Withdraw the needle slightly so that the beveled tip remains under the skin then re-palpate and redirect needle. Limit redirects to two.

2) Completely withdraw the needle, change kit, re-palpate and attempt puncture again.

After two complete puncture attempts obtain the assistance of another certified RRT/GRT.

12. When sufficient blood (~1 mL) has been collected, quickly withdraw the needle at the same angle at which it was inserted. Immediately apply firm pressure directly over the puncture site, with the sterile gauze 2 X 2, for at least 5 minutes. Pressure should be strong enough to prevent blood from leaking through the needle hole but not enough to occlude the artery. A flow of blood is necessary to bring platelets and clotting factors to the hole to plug it. At the end of the five minutes, if any bleeding occurs after 15 seconds of observation, pressure must be continued until no further bleeding occurs. Severe hematoma may occur from an arterial puncture site due to the force of arterial pressure if direct compression is not maintained long enough to occlude the puncture site.

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If a patient is taking anticoagulants or has a bleeding disorder and arterial puncture is necessary, it may take upwards of 15 minutes of direct pressure to ensure bleeding has stopped. You are advised to maintain pressure on the puncture site yourself to ensure it is done correctly as the person performing the puncture is responsible for any complications.

13. As soon as the needle is removed from the skin and pressure is being applied to the puncture site, seal the needle by inserting it into the cube (without holding onto the cube), then expel any air in the sample out the plunger vent holes. Air bubbles in the sample will normally increase PaO2 and decrease PaCO2.

After the bleeding has stopped, remove the needle and cap the syringe with a blood gas cap. Roll the syringe for 10-15 seconds to ensure complete mixing of heparin and blood. Discard the needle and cube in sharps container.

Label the syringe with the patient’s name/ID, and place it in a biohazard bag. Record puncture information (i.e. time, site, FiO2, delivery device, ventilation, etc.) in patient’s chart and/or on blood gas requisition as appropriate.

NOTE: If sample analysis may be longer then 10 minutes place sample in an ice slurry to slow metabolism which would otherwise raise PaCO2 and decrease PaO2, and may not accurately measure Lactate. If longer storage is unavoidable, store samples at 0-4o C for a maximum of 30 minutes. Ice water (with crushed ice or cooling elements) is suitable for storing samples. Samples must not be placed directly on ice, because this may cause the formation of ice crystals in the sample, producing red blood cell hemolysis. This should be noted on the report form. Also mix the sample well prior to analysis, to prevent settling out of blood cells leading to problems in hemoglobin measurement.

14. Dispose of soiled equipment in the appropriate manner for biohazardous material.

15. Thoroughly wash your hands.

16. Document procedure in patient’s chart and/or on blood gas requisition as appropriate. If complications occurred during or after the procedure the patient’s physician and attending nurse must be informed. In addition, the complication must be documented in the patient’s chart.

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REFERENCES:1. AARC Clinical Practice Guidelines, Sampling for Arterial Blood Gas Analysis

(1992). Respiratory Care, 37, 913-917.2. Canadian Pharmacists Association (2001). Compendium of Pharmaceuticals and

Specialties (36th ed.). Ottawa: Canadian Pharmacists Association.3. Eberst, M.A. (2000). Hematological and Oncologic Emergencies. In J.E.

Tintinalli, G.D. Kelen, & J.S. Stapczynski (Eds.), Emergency Medicine a Comprehensive Study Guide (5th ed.) (pp. 1365-1407). New York: McGraw-Hill.

4. Gosling, J.A., Harris, P.F., Humpherson, J.R., Whitmore, I, & Willan, P.T.L. Human Anatomy (2nd ed.). London: Gower.

5. Handin, R.J. (1994). Bleeding and Thrombosis. In K.J. Isseelbacher et al (Eds.), Harrison’s Principles of Internal Medicine (13th ed.) (pp. 317-322). New York: McGraw-Hill.

6. Malley, W.J. (1990). Clinical Blood Gases. Philadelphia: W.B. Saunders.7. Marino, P.L. (1990). Platelet Disorders and Replacement. In P.L. Marino (Ed.),

The ICU Book (2nd ed.) (pp. 709-718). Philadelphia: Williams & Wilkins.8. Pechlaner, S., Hussil, H., & Kerschbaumer, F. (2000). Atlas of Hand Surgery. New

York: Thieme.9. Scanlan, C.R. (1999). Analysis and Monitoring of Gas Exchange. In C.R.

Scanlan, R.L. Wilkins, & J.K. Stoller (Eds.), Egan’s Fundamentals of Respiratory Care (7th ed.) (pp. 337-369). St. Louis: Mosby.

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