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Chapter 12. Arterial Puncture Procedures. Objectives. State the primary reason for performing arterial punctures and identify the personnel who may be required to perform them
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Chapter 12 Arterial Puncture Procedures
Objectives • State the primary reason for performing arterial punctures and identify the personnel who may be required to perform them • Explain the purpose of collecting arterial blood gas specimens and identify and describe commonly measured ABG parameters • Identify the sites that can be used for arterial puncture, the criteria used for selection of the site, and the advantages and disadvantages of each site • List equipment and supplies needed for arterial puncture
Objectives • Identify typical required and supplemental requisition information, and describe patient assessment and preparation procedures, including the administering of local anesthetic prior to collecting arterial blood gases specimens • Explain the purpose of the modified Allen test, describe how it is performed, define what constitutes a positive or negative result, and give the procedure to follow for either result • Describe the procedure for collecting radial arterial blood gases specimens, and the role of the phlebotomist in other site collections. • List hazards and complications of arterial puncture, identify sampling errors that may affect the integrity of an arterial sample, and describe the criteria for specimen rejection
Arterial Blood Gases (ABG) • Collected by directly puncturing an artery • Arterial specimens are ideal for most testing because arterial blood is relatively consistent throughout the body • Not routinely used because collection is technically more difficult and more painful and hazardous for the patient
Arterial Blood Gases (ABG) • Primary reason is evaluation of arterial blood gases • ABG evaluation is used in: • Diagnosis and management of respiratory disease • Provides valuable information about a patient's oxygenation, ventilation, and acid‑base balance • Management of electrolyte and acid-base balance in patients with other disorders such as diabetes
ABG • Components • pH • Partial pressure of carbon dioxide (PCO2) • Oxygen pressure (PO2) • Bicarbonate (HCO3) • Oxygen saturation • Base excess
Personnel who Perform ABG • Nurses • Medical technologists • Medical lab technicians • Respiratory therapists • Emergency medical technicians • Level II phlebotomists
Arterial Puncture Sites • Criteria • Presence of collateral circulation • How large and accessible the artery is • Type of tissue surrounding the site • Sites • Radial artery • Brachial artery • Femoral artery
Radial Artery • Advantages • Good collateral flow • Less chance of hematoma formation • Disadvantages • Small size • Difficult to locate
Brachial Artery • Advantages • Easy to find because it is large • Easy to palpate • Adequate collateral circulation • Disadvantages • Deeper than radial • Close to basilic and median nerve • Increased risk of hematoma formation
Femoral Artery • Advantages • Large • Easily palpated and punctures • May be only site for patient with low cardiac output • Disadvantages • Poor collateral flow • Increased risk of infection • Very close to femoral vein
Other Sites • For infants • Scalp arteries • Umbilical arteries
ABG Specimen Requisition • Patient’s full name • Medical record or identification number • Age or date of birth • Room number or other patient location • Date and time of test collection • Fraction of inspired oxygen (FiO2) or flow rate in liters per minute (L/M) • Body temperature • Respiration rate • Clinical indication for specimen collection
ABG Specimen Requisition • Blood drawer’s initials • Requesting physician’s name • Supplemental information as required by institutional policy or regulatory agencies: • Ventilation status • Method of ventilation • Sampling site and type of procedure • Patient activity and position • Working diagnosis or ICD code
Equipment and Supplies • Personal protective equipment (PPE) • Antiseptic, gauze, and bandage • Ice (if indicated) • Sterile prepackaged kits • Heparinized syringe • Special capping device • Safety needle or needle removal device • Needle usually 22 g or smaller • Labels, sharps container, etc.
Patient Assessment and Preparation Procedures • Identification and assessment • ID patient, explain procedure, obtain consent, reassure • Verify and document collection conditions • Check for anticoagulant therapy • Steady state • At least 20-30 minutes before obtaining sample • Do not perform until steady state has been achieved • Exception: emergency situations
Patient Preparation • Modified Allen test • Assesses collateral circulation • No special equipment necessary • Steps: • Have the patient make a tight fist • Apply pressure to the patient's wrist, compressing both the radial and ulnar arteries at the same time • While maintaining pressure, have the patient open the hand slowly • Release pressure on the ulnar artery only • Assess results • Record the results on the request slip
Modified Allen Test • Positive Allen test result • Hand flushed pink or returns to normal color within 15 seconds. Arterial puncture can be performed on radial artery • Negative Allen test result • Hand does not flush or return to normal color within 15 seconds. Radial artery should not be used
Patient Preparation • Administration of local anesthetic • Routine administration unnecessary because of thin-wall needles • Blood gas results affected by patient anxiety • Local anesthetic used is 1% lidocaine with epinephrine • May cause prolonged bleeding in patients on anticoagulant therapy
Radial ABG Procedure • Position arm • Locate the artery • Clean the site • Prepare equipment • Insert the needle • Advance the needle into the artery • Withdraw the needle and apply pressure • Remove air, cap, and mix • Check the site • Transport and handle
ABG Collection from Other Sites • Similar to radial punctures • Not usually performed by phlebotomists • Phlebotomists may be asked to provide equipment and assistance • Labeling specimens • Transporting specimens
Hazards and Complications • Arteriospasm = reflex (involuntary) contraction of the artery • Discomfort • Infection • Hematoma • Numbness • Thrombus formation = injury to the inner wall of the artery can lead to clot formation • Vasovagal syncope = faintness or loss of consciousness
Sampling Errors • Air bubbles • Delay in analysis • Improper mixing • Improper syringe • Obtaining a venous sample by mistake • Use of improper anticoagulants • Use of too much or too little heparin
Criteria for Rejection • Air bubbles in specimen • Clotted specimen • Hemolysis • Improper or absent labeling • Improper transportation temperature • Inadequate volume of specimen for the test (QNS) • Prolonged delay in delivery to the lab • Use of wrong syringe