Arterial Puncture: PMTP LAB FINALS

What is the primary purpose of the Modified Allen’s Test?

To assess collateral circulation: The test determines if the ulnar artery can supply blood to the hand if the radial artery is compromised during arterial puncture, ensuring the hand remains oxygenated.

Which artery is the preferred site for arterial puncture?

Radial artery: It is preferred due to its accessibility, ease of palpation, good collateral circulation via the ulnar artery, and fewer nearby nerves, making it less painful.

What is the name of the anastomosis connecting the radial and ulnar arteries?

Radial arch: This structure allows collateral circulation, enabling the ulnar artery to compensate if the radial artery fails to deliver blood to the hand.

What does a positive Modified Allen’s Test result indicate?

Good ulnar artery compensation: The hand returns to its normal pink/red color within 15 seconds after releasing pressure on the ulnar artery, showing the ulnar artery can supply blood.

What is the time threshold for a positive Modified Allen’s Test result?

15 seconds: If the hand regains normal color within 15 seconds after releasing ulnar artery pressure, it indicates adequate collateral circulation.

What is the main clinical application of arterial puncture?

Arterial blood gas (ABG) analysis: It assesses lung capacity and acid-base balance, not routine blood tests, which use venous blood.

Why is arterial puncture more painful than venipuncture?

Proximity to nerves and thicker artery walls: Arteries are near nerves and have thicker, more elastic walls, increasing pain during puncture.

What is the role of heparin in arterial puncture syringes?

Prevents blood clotting: Heparin ensures the blood sample remains liquid for accurate ABG analysis by preventing coagulation.

What is the recommended angle for inserting the needle during radial arterial puncture? towards where?

45 degrees: The needle is inserted at a 45-degree angle toward the heart to align with blood flow and ensure proper collection.

Why should the plunger not be pulled during arterial puncture?

To avoid artery damage: Arterial blood flows naturally due to heart pressure; pulling the plunger adds unnecessary pressure, risking trauma.

What is the minimum duration to apply pressure after arterial puncture?

2 minutes: Pressure is applied for at least 2 minutes (preferably 5) to stop bleeding due to high arterial pressure.

What does a negative Modified Allen’s Test result indicate?

Poor ulnar artery compensation: The hand remains pale or takes >15 seconds to regain color, indicating the ulnar artery cannot adequately supply blood.

Which artery is used only in emergencies for arterial puncture?

Femoral artery: Located in the groin, it’s the largest but used only in emergencies due to the risk of reducing blood to the leg/foot.

What is the purpose of removing air bubbles from the syringe in arterial puncture?

To ensure accurate ABG results: Air bubbles can alter oxygen and carbon dioxide levels, skewing blood gas analysis.

Why is the Evacuated Tube System (ETS) not used for arterial puncture?

Vacuum pressure damages arteries: ETS applies suction, which can harm the artery; arterial puncture relies on natural blood flow.

What is one key criterion for arterial puncture site selection?

Presence of collateral circulation: The site must have a backup artery to ensure blood supply if the punctured artery is compromised.

Why is the radial artery easy to use for arterial puncture?

It is well-anchored and easy to palpate: Its stable position and accessibility on the thumb side of the wrist make it ideal for puncture.

What is the location of the brachial artery for arterial puncture?

Above the elbow (antecubital fossa): It is felt in line with the ring finger, but its proximity to the basilic vein increases the risk of venous puncture.

What type of training is required for phlebotomists performing arterial puncture?

Extensive training: Includes theory, technique demonstration, observation of procedures, and supervised performance to ensure safety and accuracy.

What is one reason the femoral artery is risky for arterial puncture?

Risk of reduced leg/foot blood supply: Damage to this major artery can limit oxygenated blood to the lower limb, especially in patients with poor circulation.

What is the anatomical location of the radial artery for arterial puncture?

Thumb side of the wrist: It is located on the lateral aspect of the wrist, making it accessible and easy to palpate for puncture.

What is the purpose of asking the patient to make a tight fist during the Modified Allen’s Test?

To blanch the hand: Clenching the fist drains blood from the hand, creating a pale appearance to assess blood flow return when arteries are released.

What is the name of the artery that compensates for the radial artery in collateral circulation?

Ulnar artery: Located on the pinky side of the wrist, it supplies blood to the hand if the radial artery is compromised.

Why is the Modified Allen’s Test performed before arterial puncture?

To ensure hand oxygenation: It confirms the ulnar artery can maintain blood supply if the radial artery is damaged, preventing tissue damage.

What is one reason arterial puncture requires specialized training?

High risk of complications: The procedure is painful, involves high-pressure arteries, and risks reducing blood supply, necessitating expertise.

What is the role of the luer-tip or bubble removal cap in arterial puncture?

Maintains anaerobic condition: It prevents air entry into the syringe, ensuring accurate measurement of blood gases.

Why is local anesthetic optional in arterial puncture?

Pain tolerance varies: The procedure is painful, but some patients may prefer to avoid anesthetic due to quick execution or sensitivity.

What is one disadvantage of using the brachial artery for arterial puncture?

Proximity to basilic vein: Its closeness to the vein increases the risk of accidentally collecting venous blood, affecting ABG results.

What is one condition that contraindicates arterial puncture at a site?

Presence of hematoma: Hematoma indicates prior trauma or bleeding, increasing the risk of complications or inaccurate sampling.

What is the anatomical location of the femoral artery for arterial puncture?

Groin, lateral to the pubic bone: It is superficially located, making it accessible but risky due to its role in leg blood supply.

Why is the ulnar artery not typically used for arterial puncture?

Poor accessibility: It is less superficial and harder to palpate compared to the radial artery, making it unsuitable for routine puncture.

What is one advantage of the radial artery for arterial puncture?

Fewer nearby nerves: Its location reduces pain compared to other arteries, as it is not closely surrounded by nerve tissue.

What is one type of tissue to avoid when selecting an arterial puncture site?

Scar tissue: Areas with scar tissue, such as from burns, are less viable for puncture due to altered tissue structure and blood flow.

Why is the Modified Allen’s Test quick to perform?

Takes less than 1 minute: The simple steps of fist clenching, artery compression, and color assessment are rapid, ensuring efficiency.

What is the standard time threshold for a positive Modified Allen’s Test result?

15 seconds: The hand should return to its normal pink/red color within 15 seconds after releasing ulnar artery pressure, indicating adequate collateral circulation.

What is the maximum time for a negative Modified Allen’s Test result?

Greater than 15 seconds: If the hand takes longer than 15 seconds to regain color, it indicates poor ulnar artery compensation, ruling out radial artery puncture.

What is the minimum duration for applying pressure after arterial puncture?

2 minutes: Pressure is applied for at least 2 minutes to stop bleeding due to the high pressure in arteries.

What is the preferred duration for applying pressure after arterial puncture to ensure no bleeding?

5 minutes: Respiratory therapists often apply pressure for 5 minutes to ensure the arterial puncture site is fully sealed, given the risk of prolonged bleeding.

What is the standard angle for needle insertion during radial arterial puncture?

45 degrees: The needle is inserted at a 45-degree angle toward the heart to align with arterial blood flow for effective collection.

Enumerate the five main steps of the Modified Allen’s Test procedure.

Steps: 1. Ask the patient to make a tight fist. 2. Use index and middle fingers of both hands to apply pressure to the radial and ulnar arteries. 3. Have the patient slowly open their hand. 4. Release pressure on the ulnar artery only. 5. Assess the hand’s color return within 15 seconds. Explanation: These steps ensure the ulnar artery’s ability to compensate is tested by blanching the hand, blocking blood flow, and observing color return to confirm collateral circulation.

Enumerate the standard time thresholds for positive and negative Modified Allen’s Test results.

Thresholds: 1. Positive: Hand regains color within 15 seconds. 2. Negative: Hand takes longer than 15 seconds to regain color. Explanation: These times determine if the ulnar artery can adequately supply blood, with 15 seconds as the critical cutoff for safe radial artery puncture.

Enumerate the steps for applying pressure during the Modified Allen’s Test.

Steps: 1. Use the index and middle fingers of both hands. 2. Apply even pressure to both radial and ulnar arteries simultaneously. 3. Maintain pressure while the patient opens their hand. 4. Release pressure on the ulnar artery only. Explanation: This sequence blocks blood flow to blanch the hand and tests ulnar artery function by selectively releasing pressure.

Enumerate the standard pressure application durations after arterial puncture.

Durations: 1. Minimum: 2 minutes. 2. Preferred: 5 minutes. Explanation: Arteries have high pressure, requiring at least 2 minutes of pressure to stop bleeding, with 5 minutes preferred to ensure no complications, especially in high-risk cases.

Enumerate the key steps on how to do needle insertion during radial arterial puncture.

Steps: 1. Hold the syringe like a dart with the bevel up. 2. Insert the needle at a 45-degree angle toward the heart. 3. Allow blood to flow naturally without pulling the plunger. Explanation: These steps ensure proper alignment with arterial flow, minimize trauma, and utilize heart pressure for blood collection.

Enumerate the standard time ranges for a positive Modified Allen’s Test result as mentioned in the text.

Ranges: 1. 15 seconds (lecture notes). 2. 15-20 seconds (some sources). Explanation: The text specifies 15 seconds as the primary threshold but notes 15-20 seconds in other contexts, indicating a positive result when the hand regains color quickly.

Enumerate the steps to ensure a proper arterial blood sample after collection.

Steps: 1. Remove the needle and apply pressure for 2-5 minutes. 2. Gently mix the syringe to blend blood with heparin. 3. Remove any air bubbles from the syringe. Explanation: These steps prevent bleeding, ensure the sample remains unclotted, and maintain accuracy for ABG analysis by eliminating air contamination.

Enumerate the standard criteria for assessing the Modified Allen’s Test result.

Criteria: 1. Hand returns to pink/red color within 15 seconds (positive). 2. Hand remains pale or takes longer than 15 seconds (negative). Explanation: These criteria evaluate ulnar artery compensation, determining if radial artery puncture is safe based on color return speed.

Enumerate the steps for preparing the patient before arterial puncture.

Steps: 1. Identify the patient. 2. Orient the patient on the procedure. 3. Wash hands and wear gloves. 4. Palpate the radial artery. 5. Perform the Modified Allen’s Test. Explanation: These steps ensure patient safety, confirm the puncture site, and verify collateral circulation before proceeding.