Intraosseous Access Practice Questions

65 multiple-choice questions on Intraosseous access for paramedic and EMT students, from Chapter 14 (Medication Administration). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

65 practice questions

1. Intraosseous access delivers medications into the:

   1. A. Compact bone of the cortex
   2. B. Periosteum covering the bone
   3. C. Medullary cavity of the bone
   4. D. Synovial space of the nearby joint
   Show answer

   Answer: C. Medullary cavity of the bone

   Onset is comparable to IV. The medullary cavity drains into the venous circulation.

2. Intraosseous access is indicated when:

   1. A. The patient is alert and stable
   2. B. IV access fails in a critical patient
   3. C. Transport time to the hospital is short
   4. D. Before an IV is tried in adult arrest
   Show answer

   Answer: B. IV access fails in a critical patient

   IO access is for critically ill or injured patients who need drugs or fluids when IV access fails or cannot be obtained quickly. For adult cardiac arrest, the 2025 AHA guidelines recommend trying IV access first and using IO if IV attempts are unsuccessful or not feasible. A stable, alert patient, a short transport, or skipping the IV attempt in adult arrest are not indications.

3. Common IO insertion sites include:

   1. A. Patella, distal fibula, and ulna
   2. B. Proximal tibia, distal tibia, humerus
   3. C. Femoral shaft, clavicle, and radius
   4. D. Iliac crest, ulna, and calcaneus
   Show answer

   Answer: B. Proximal tibia, distal tibia, humerus

   Site choice depends on the device and patient age. The humeral site is the proximal humerus.

4. A contraindication to IO insertion at a given site includes:

   1. A. Obesity or a large body habitus
   2. B. Patient age greater than 65 years
   3. C. Any fracture elsewhere in the body
   4. D. Fracture or prior IO in that bone
   Show answer

   Answer: D. Fracture or prior IO in that bone

   Prosthetic joints near the site are another consideration. Infection over the site is also a contraindication.

5. Correct IO placement is suggested by:

   1. A. A stable needle and a smooth flush
   2. B. Bleeding around the insertion site
   3. C. Rapid gravity flow in every single case
   4. D. Pain reported during needle insertion
   Show answer

   Answer: A. A stable needle and a smooth flush

   Watch for swelling behind the site during the flush. The needle should stand without support and the flush should infuse without infiltration; marrow aspiration supports placement but may be absent.

6. IO infusion in a conscious patient is:

   1. A. Painless once the needle is seated
   2. B. Not permitted in conscious adults
   3. C. Painful, so lidocaine is given first
   4. D. Best done without warning the patient
   Show answer

   Answer: C. Painful, so lidocaine is given first

   Slow lidocaine administration improves tolerance. Pain occurs mainly during flush and infusion; give lidocaine per protocol before flushing.

7. IO flow often requires:

   1. A. Switching to a smaller-gauge needle
   2. B. Gravity alone at a high hang height
   3. C. A microdrip administration set
   4. D. A pressure bag or syringe pushes
   Show answer

   Answer: D. A pressure bag or syringe pushes

   Expect slower rates than a large-bore IV. The marrow resists flow.

8. A complication of IO access includes:

   1. A. Phlebitis along the cannulated vein
   2. B. Pneumothorax from the needle tip
   3. C. Air embolism as the only real risk
   4. D. Extravasation and compartment syndrome
   Show answer

   Answer: D. Extravasation and compartment syndrome

   Monitor the limb after insertion. Infection and fracture can also occur.

9. Medications that can be given IO include:

   1. A. Any drug or fluid given IV
   2. B. Only weight-based pediatric drugs
   3. C. Only cardiac arrest drugs
   4. D. Only crystalloid fluids
   Show answer

   Answer: A. Any drug or fluid given IV

   Blood products can also be given through an IO.

10. An IO needle should generally be:

    1. A. Removed before transport begins
    2. B. Left in place for several days
    3. C. Replaced within about 24 hours
    4. D. Used for only a single drug dose
    Show answer

    Answer: C. Replaced within about 24 hours

    Document the site and time of insertion. Definitive vascular access is established at the hospital.

11. In two large recent randomized trials (PARAMEDIC-3 and IVIO) of adult out-of-hospital cardiac arrest, an IO-first strategy compared with IV-first:

    1. A. Did not improve 30-day survival
    2. B. Doubled survival to hospital discharge
    3. C. Was stopped for causing tibial fractures
    4. D. Proved IO drugs reach the heart slower
    Show answer

    Answer: A. Did not improve 30-day survival

    The PARAMEDIC-3 and IVIO trials found no improvement in survival with an IO-first strategy, which supports the 2025 AHA recommendation to try IV access first and use IO if IV fails or is not feasible. Neither trial showed doubled survival, neither was stopped for fractures, and neither measured drug transit time.

12. The most common adult IO site is the:

    1. A. Proximal tibia
    2. B. Radius
    3. C. Distal femur
    4. D. Sternum
    Show answer

    Answer: A. Proximal tibia

    The proximal tibia is accessible with clear landmarks.

13. The proximal tibia IO insertion site in adults is located:

    1. A. At the joint line just below the patella
    2. B. Directly on the tibial tuberosity
    3. C. Just lateral to the tibial tuberosity
    4. D. Flat surface medial to the tuberosity
    Show answer

    Answer: D. Flat surface medial to the tuberosity

    Flat medial surface avoids the growth plate and tuberosity. The site is about 2 cm below the patella and 2 cm medial to the tibial tuberosity.

14. The proximal humerus IO site is advantageous because:

    1. A. It needs no anatomic landmarks at all
    2. B. It gives faster flow than the tibia
    3. C. It requires a shorter, smaller needle
    4. D. It avoids the need for any lidocaine flush
    Show answer

    Answer: B. It gives faster flow than the tibia

    Humeral IO delivers fluid at rates closer to central access. Infusion may also be less painful than at the tibia.

15. For proximal humerus IO, the arm should be positioned:

    1. A. Extended with the palm facing up
    2. B. Raised overhead with the palm forward
    3. C. Adducted, hand resting on the abdomen
    4. D. Abducted 90 degrees from the body
    Show answer

    Answer: C. Adducted, hand resting on the abdomen

    Positioning rotates the greater tubercle anteriorly. This internal rotation exposes the greater tubercle.

16. A trauma patient has an unstable pelvic fracture. Why is the proximal humerus usually chosen over a tibial IO?

    1. A. Adult tibias hold too little marrow
    2. B. Humeral IO needs no lidocaine flush
    3. C. Leg IOs raise the risk of fat embolism
    4. D. Fluid may not pass the injury above it
    Show answer

    Answer: D. Fluid may not pass the injury above it

    Fluid infused below a major pelvic or proximal leg injury may leak into the injured area instead of reaching the central circulation, so an upper-extremity site is preferred. Adult tibias have usable marrow, an awake patient needs lidocaine at either site, and fat embolism risk is not the reason for the choice.

17. Before starting an infusion through a new adult IO, the needle is flushed with about:

    1. A. 10 mL of saline
    2. B. 1 mL of saline
    3. C. 100 mL of saline
    4. D. 500 mL of saline
    Show answer

    Answer: A. 10 mL of saline

    Teleflex guidance: flush an adult IO with about 10 mL of saline (5 mL in children) to clear marrow from the needle and open the space ('no flush, no flow'). 1 mL is too little to open the space, and 100 or 500 mL are infusion volumes, not a flush.

18. The usual initial IO lidocaine dose for an awake adult is:

    1. A. 400 mg as a rapid push
    2. B. 4 mg mixed in a 1-L bag of saline
    3. C. 40 mg rapidly over 2 seconds
    4. D. 40 mg slowly over about 2 minutes
    Show answer

    Answer: D. 40 mg slowly over about 2 minutes

    Teleflex guidance for adults: 40 mg of preservative-free 2% lidocaine slowly over about 2 minutes, a 1-minute dwell, a saline flush, then 20 mg more over a minute; 0.5 mg/kg in children. 400 mg is a toxic dose, 4 mg in a liter would do nothing, and a rapid push can cause toxicity and is less effective.

19. An IO needle wobbles and fluid leaks around it during the flush. This suggests:

    1. A. Normal seating that needs more tape
    2. B. It is misplaced; use a different bone
    3. C. A need to push the fluid harder
    4. D. Success, confirmed by the leaking fluid
    Show answer

    Answer: B. It is misplaced; use a different bone

    A correctly placed IO needle stands firmly in the bone and flushes without leaking or swelling; a wobbly needle with leakage is misplaced, so remove it and use another bone. Tape will not fix a misplaced needle, pushing harder causes extravasation, and leakage is a sign of failure.

20. Can blood products be transfused through an IO line?

    1. A. No, the marrow would destroy the red cells
    2. B. No, IO lines are for crystalloid
    3. C. Yes, usually with a pressure device
    4. D. Yes, plasma but not red cells
    Show answer

    Answer: C. Yes, usually with a pressure device

    Blood and blood products can be given IO, usually with a pressure bag or syringe to reach useful flow. The marrow does not destroy transfused red cells, IO lines carry drugs and blood as well as crystalloid, and both plasma and red cells can be given.

21. The distal tibia IO site is located:

    1. A. Just proximal to the lateral malleolus
    2. B. Just proximal to the medial malleolus
    3. C. Midway down the anterior shin
    4. D. On the tip of the lateral malleolus
    Show answer

    Answer: B. Just proximal to the medial malleolus

    Distal tibia is an alternative site in adults and children. In children it is about 1–2 cm above the medial malleolus (about 3 cm in adults). The bone above the lateral malleolus is the fibula, which is too thin, and the mid-shin has dense cortex and no reliable landmark.

22. The distal femur IO site is used primarily in:

    1. A. Adults in cardiac arrest
    2. B. Older adults with osteoporosis
    3. C. Infants and young children
    4. D. Obese adult patients
    Show answer

    Answer: C. Infants and young children

    In infants and small children the distal femur is an option.

23. An awake 20-kg child needs IO lidocaine 0.5 mg/kg using 2% lidocaine (20 mg/mL). What volume?

    1. A. 0.5 mL
    2. B. 5 mL
    3. C. 1 mL
    4. D. 0.05 mL
    Show answer

    Answer: A. 0.5 mL

    20 kg x 0.5 mg/kg = 10 mg, and 10 mg / 20 mg/mL = 0.5 mL, given slowly. 5 mL (100 mg) is a tenfold overdose, 1 mL doubles the dose, and 0.05 mL is a tenfold underdose.

24. The sternal IO device is used in:

    1. A. Infants in the delivery setting
    2. B. Children under eight years old
    3. C. Adults, often in military settings
    4. D. Older adults with chest trauma
    Show answer

    Answer: C. Adults, often in military settings

    Sternal IO (e.g., FAST1) is contraindicated in children and chest trauma.

25. IO needle length selection depends on:

    1. A. The type of drug to be given
    2. B. The patient's age alone
    3. C. Soft-tissue depth over the site
    4. D. The flow rate that is needed
    Show answer

    Answer: C. Soft-tissue depth over the site

    Too short a needle fails to reach marrow in obese patients. Tissue depth reflects weight and body habitus.

26. After inserting an IO needle, the paramedic should:

    1. A. Secure it and attach primed tubing
    2. B. Leave it unsecured for easy removal
    3. C. Remove the stylet and leave it open
    4. D. Tape the hub with a single strip
    Show answer

    Answer: A. Secure it and attach primed tubing

    Stabilization prevents dislodgement. Use a stabilizer dressing and primed extension tubing.

27. The powered IO driver should be stopped when:

    1. A. You feel a sudden loss of resistance
    2. B. Ten seconds of drilling have passed
    3. C. The needle tip first touches skin
    4. D. The patient flinches or reports pain
    Show answer

    Answer: A. You feel a sudden loss of resistance

    Stop the driver at the sudden loss of resistance (the 'pop') that signals the needle has passed through the cortex into the marrow. Drilling time varies with bone density rather than following a fixed count, the needle is pushed through the skin to the bone before the driver is run, and insertion pain in a conscious patient is expected and does not show the needle position.

28. Signs of IO extravasation include:

    1. A. Increased flow and a softer limb
    2. B. Redness along a superficial vein
    3. C. Loss of the distal pulse only
    4. D. Swelling, firmness, and slowed flow
    Show answer

    Answer: D. Swelling, firmness, and slowed flow

    Stop the infusion and remove the needle.

29. For an adult of normal size (40 kg or more) at the proximal tibia, the usual powered IO needle is:

    1. A. 15 mm (pink)
    2. B. 25 mm (blue)
    3. C. 45 mm (yellow)
    4. D. 5 mm (clear)
    Show answer

    Answer: B. 25 mm (blue)

    The 25-mm (blue) needle fits most adults at the proximal tibia; confirm that at least one black 5-mm mark shows above the skin when the tip touches bone. The 15-mm (pink) needle is for about 3 to 39 kg, the 45-mm (yellow) for the humerus or thick tissue, and there is no 5-mm needle set.

30. A 10-kg child in shock has a tibial IO. A 20-mL/kg bolus is best delivered by:

    1. A. Gravity drip from a bag hung up high
    2. B. Syringe push-pull in measured amounts
    3. C. A 60 gtt/mL microdrip set run wide open
    4. D. Squeezing the IV bag by hand
    Show answer

    Answer: B. Syringe push-pull in measured amounts

    The marrow resists flow, so pediatric IO boluses (here 200 mL) are pushed by syringe through a three-way stopcock in measured amounts, which is both fast and accurate. Gravity flow and a microdrip set are far too slow through an IO, and squeezing a bag gives an unmeasured volume.

31. Manual IO needles (e.g., Jamshidi) are:

    1. A. Obsolete and no longer used anywhere
    2. B. Twisted in by hand, mainly in children
    3. C. Intended only for large adult patients
    4. D. Battery-powered drill devices
    Show answer

    Answer: B. Twisted in by hand, mainly in children

    Manual devices are still used, especially in infants.

32. The growth plate concern in pediatric IO means:

    1. A. Insert through the knee joint instead
    2. B. IO is contraindicated in all children
    3. C. Use only adult-size needles in children
    4. D. Insert away from the epiphyseal plate
    Show answer

    Answer: D. Insert away from the epiphyseal plate

    Growth plate injury is avoided by proper landmarks. For example, insert 1–2 cm below the tibial tuberosity.

33. Blood samples drawn from an IO:

    1. A. Are identical to venous blood samples
    2. B. Are preferred over venous blood draws
    3. C. Can never be sent to the laboratory
    4. D. Are reliable only for some tests
    Show answer

    Answer: D. Are reliable only for some tests

    Marrow aspirate is acceptable for glucose and some chemistries with caveats. Notify the lab that the sample is marrow.

34. After a tibial IO infusion, the earliest sign of compartment syndrome is usually:

    1. A. Loss of the pedal pulses
    2. B. A cold, white, numb foot
    3. C. Bruising at the insertion site
    4. D. Severe pain on passive stretch
    Show answer

    Answer: D. Severe pain on passive stretch

    Pain out of proportion to the injury, especially on passive stretch of the muscles, is the earliest sign; check the calf often during IO infusion. Loss of pulses and a cold, white, numb foot are late findings, and bruising at the site is not specific.

35. Osteomyelitis after IO is:

    1. A. Common, occurring in about 1 in 5 cases
    2. B. Expected in nearly every IO patient
    3. C. Unrelated to the insertion technique
    4. D. Rare with proper aseptic technique
    Show answer

    Answer: D. Rare with proper aseptic technique

    Infection risk is low but increases with longer dwell times. The rate is under 1%.

36. A 6-year-old in septic shock has two failed IV attempts over 90 seconds. The best next step is:

    1. A. Give fluids orally in small sips
    2. B. Place an IO needle in the proximal tibia
    3. C. Administer medications intramuscularly only
    4. D. Continue IV attempts until one succeeds
    Show answer

    Answer: B. Place an IO needle in the proximal tibia

    IO access is indicated when IV access cannot be obtained rapidly in critically ill patients.

37. An adult in cardiac arrest has a fractured right tibia. The best IO site choice is:

    1. A. The right proximal tibia above the fracture
    2. B. The proximal humerus or the left tibia
    3. C. The right distal tibia below the fracture
    4. D. The sternum using a tibial device
    Show answer

    Answer: B. The proximal humerus or the left tibia

    A fractured bone will leak infused fluid; choose a different bone.

38. Which finding at the intended tibial site is a contraindication to IO insertion there?

    1. A. Cellulitis over the insertion site
    2. B. An IO already in the opposite tibia
    3. C. A cast on the opposite leg
    4. D. Hypotension from septic shock
    Show answer

    Answer: A. Cellulitis over the insertion site

    Infection at the site risks osteomyelitis. An IO or cast on the other leg does not affect this site, and shock is a common reason to place an IO, not a reason to avoid one.

39. Before tibial IO insertion, a previous IO attempt was made in the same bone an hour earlier. The concern is:

    1. A. The bone will be more likely to fracture
    2. B. The marrow will have healed and be too hard
    3. C. There is no concern with reusing the same bone
    4. D. Fluid may leak out of the earlier puncture hole
    Show answer

    Answer: D. Fluid may leak out of the earlier puncture hole

    A prior IO hole in the same bone allows extravasation; use a different bone.

40. For proximal tibial IO insertion in an infant, the site is:

    1. A. Lateral surface, 3 cm above the knee
    2. B. Flat medial surface below the tuberosity
    3. C. Just above the top edge of the patella
    4. D. Posterior calf just below the knee
    Show answer

    Answer: B. Flat medial surface below the tuberosity

    This avoids the growth plate while reaching marrow on the flat anteromedial tibia. The site is about 1 cm below and slightly medial to the tibial tuberosity.

41. When inserting a proximal humerus IO, the needle is angled:

    1. A. About 45°, aimed posteromedially
    2. B. 90° straight down toward the floor
    3. C. 15°, nearly flat along the skin
    4. D. Toward the patient's head at 30°
    Show answer

    Answer: A. About 45°, aimed posteromedially

    With the arm adducted and internally rotated, the needle enters the greater tubercle at about 45 degrees to the anterior plane, aimed posteromedially into the humeral head. A vertical approach, a nearly flat angle, or aiming toward the head can miss the marrow or enter the joint.

42. When using a powered IO driver on an adult tibia, the paramedic should:

    1. A. Push through bone without powering the driver
    2. B. Drill at a 45-degree angle toward the foot
    3. C. Drill until the needle hub touches the skin
    4. D. Touch bone, check the 5-mm mark, then drill
    Show answer

    Answer: D. Touch bone, check the 5-mm mark, then drill

    Seeing at least one black line (5 mm) above the skin when the tip touches bone confirms adequate needle length.

43. A paramedic chooses the 45-mm (yellow) powered IO needle for:

    1. A. Neonates and small infants at the tibia
    2. B. Adult humerus or thick soft tissue
    3. C. Any tibial site in children under 3 kg
    4. D. Any patient who weighs under 10 kg
    Show answer

    Answer: B. Adult humerus or thick soft tissue

    Longer needles are needed for the humerus and for patients with thick soft tissue.

44. A 15-mm (pink) IO needle is generally intended for:

    1. A. All adult patients at any site
    2. B. Patients weighing about 3 to 39 kg
    3. C. Adults over 40 kg at the humerus
    4. D. Obese adults at the tibia
    Show answer

    Answer: B. Patients weighing about 3 to 39 kg

    The shortest needle suits small patients with little tissue over the bone.

45. Immediately after IO placement, aspirating marrow is not obtained. The paramedic should:

    1. A. Begin infusing without checking the site
    2. B. Insert the stylet back into the needle
    3. C. Flush with saline and watch for swelling
    4. D. Remove the needle immediately and try again
    Show answer

    Answer: C. Flush with saline and watch for swelling

    Inability to aspirate is common; easy flush without extravasation still supports correct placement.

46. A conscious adult needs IO infusion. Lidocaine is given through the IO line:

    1. A. Only after the fluid infusion is running
    2. B. Into the skin around the needle site
    3. C. Slowly before the flush, then let it dwell
    4. D. Rapidly by forceful push without flushing
    Show answer

    Answer: C. Slowly before the flush, then let it dwell

    Slow preservative-free lidocaine before the flush reduces the pain of marrow pressurization.

47. If the powered IO driver fails partway through insertion, the paramedic may:

    1. A. Push it in by force without twisting
    2. B. Leave it and flush to seat it deeper
    3. C. Finish by hand, twisting the needle in
    4. D. Restart in the same hole with a new driver
    Show answer

    Answer: C. Finish by hand, twisting the needle in

    If the driver fails, remove it and finish the insertion by hand, grasping the hub and twisting clockwise with steady pressure until the needle enters the marrow. Forcing it in without twisting can fracture the bone or bend the needle, a flush cannot seat a partly placed needle, and a second attempt in the same bone allows extravasation.

48. While infusing through a tibial IO, the calf becomes swollen and firm. The paramedic should:

    1. A. Leave the needle in and slow the rate
    2. B. Raise the pressure to clear the line
    3. C. Stop the infusion and remove the needle
    4. D. Massage the calf to disperse the fluid
    Show answer

    Answer: C. Stop the infusion and remove the needle

    Extravasation into soft tissue can cause compartment syndrome. Monitor for compartment syndrome.

49. How should an IO needle be stabilized after placement?

    1. A. By holding the hub by hand at all times
    2. B. None needed once the needle is seated
    3. C. With a stabilizer and secured tubing
    4. D. By taping the limb to the stretcher
    Show answer

    Answer: C. With a stabilizer and secured tubing

    Securing the needle prevents dislodgement during movement.

50. When removing an IO needle, the paramedic should:

    1. A. Cut the hub and leave the needle in bone
    2. B. Pull it out at an angle without rotating
    3. C. Rotate clockwise while pulling straight out
    4. D. Rotate counterclockwise while pushing in
    Show answer

    Answer: C. Rotate clockwise while pulling straight out

    Clockwise rotation with straight traction removes the needle while avoiding unthreading or bending. Attach a syringe first and apply pressure afterward.

51. Which is a contraindication to IO insertion at the proximal humerus?

    1. A. Prior shoulder replacement on that side
    2. B. A prior IO placed in the opposite humerus
    3. C. Patient weight over 40 kilograms
    4. D. A fractured tibia on the same side
    Show answer

    Answer: A. Prior shoulder replacement on that side

    Prosthetic joints and prior orthopedic hardware are contraindications at that site. An IO in the other arm or a leg fracture does not affect this humerus, and weight over 40 kg simply calls for a longer needle.

52. Which condition increases the risk of fracture during IO insertion?

    1. A. Osteogenesis imperfecta
    2. B. Isolated head injury
    3. C. Type 2 diabetes
    4. D. Mild dehydration
    Show answer

    Answer: A. Osteogenesis imperfecta

    Brittle bone disease is a contraindication because the bone may fracture.

53. Compared with central venous catheter placement in an emergency, IO access is:

    1. A. Slower, and it requires ultrasound guidance
    2. B. Riskier for pneumothorax
    3. C. Faster, with high first-try success
    4. D. Limited to fluid, not drugs
    Show answer

    Answer: C. Faster, with high first-try success

    Studies show IO access takes about a minute or two with a high first-attempt success rate, versus several minutes for a central line. IO does not require ultrasound, it carries no pneumothorax risk (subclavian lines do), and it carries drugs as well as fluid.

54. A humeral IO is placed. When moving the patient, the arm should be:

    1. A. Raised overhead to improve flow
    2. B. Allowed to move freely at the side
    3. C. Kept adducted and immobilized
    4. D. Rotated outward and abducted
    Show answer

    Answer: C. Kept adducted and immobilized

    Arm movement can dislodge a humeral IO needle.

55. Which finding suggests the IO needle has passed through both cortices of the bone?

    1. A. Firm resistance as the needle seats
    2. B. The needle standing upright unsupported
    3. C. Marrow aspirated into the syringe
    4. D. Swelling on the far side when flushing
    Show answer

    Answer: D. Swelling on the far side when flushing

    Through-and-through placement causes infused fluid to leak out the far side.

56. In newborn resuscitation, IV or IO epinephrine is dosed at:

    1. A. 0.01 to 0.03 mg/kg
    2. B. 0.1 to 0.3 mg/kg
    3. C. 1 mg, the adult dose
    4. D. 0.5 mg/kg
    Show answer

    Answer: A. 0.01 to 0.03 mg/kg

    Neonatal guidelines dose IV/IO epinephrine at 0.01 to 0.03 mg/kg (0.02 mg/kg is commonly used) of the 0.1 mg/mL concentration. 0.1 mg/kg is the older endotracheal range and is ten times the IV dose, 1 mg is the adult dose, and 0.5 mg/kg is a massive overdose.

57. Which blood test from IO marrow aspirate is generally reliable?

    1. A. White blood cell count
    2. B. Blood glucose
    3. C. Potassium in all patients
    4. D. Platelet count
    Show answer

    Answer: B. Blood glucose

    Glucose correlates reasonably with venous values; cell counts and some electrolytes do not.

58. When using a powered IO driver, the paramedic should apply:

    1. A. Full body weight to speed the insertion
    2. B. Gentle, steady pressure; let it work
    3. C. Rocking motions side to side
    4. D. Rapid in-and-out pumping motions
    Show answer

    Answer: B. Gentle, steady pressure; let it work

    Let the driver's rotation do the work with gentle, steady downward pressure; excess force can bend the needle or push it through the far cortex. Full body weight, rocking, and pumping motions risk misplacement, fractures, or a loose needle.

59. After pushing a drug through an IO during a cardiac arrest, you should:

    1. A. Follow it with a saline flush
    2. B. Wait 5 minutes before flushing
    3. C. Aspirate marrow to confirm drug delivery
    4. D. Massage the bone above the IO site
    Show answer

    Answer: A. Follow it with a saline flush

    As with an IV, follow each IO drug with a saline flush (about 10 mL in adults) to move it out of the marrow space into the circulation. Delaying the flush delays drug delivery, aspirating marrow does not confirm the drug arrived, and massaging the bone does nothing.

60. A 15-kg child in septic shock receives two 20-mL/kg boluses through an IO. What total volume was given?

    1. A. 300 mL
    2. B. 40 mL
    3. C. 6,000 mL
    4. D. 600 mL
    Show answer

    Answer: D. 600 mL

    Each bolus is 15 kg x 20 mL/kg = 300 mL, so two boluses total 600 mL, with reassessment for crackles or liver enlargement after each. 300 mL counts only one bolus, 40 mL forgets to multiply by weight, and 6,000 mL is a tenfold error.

61. After placing an IO, what must be documented?

    1. A. Site, needle size, and time placed
    2. B. Only the patient's pain score
    3. C. Only the color of the needle hub
    4. D. Only the brand of IO device used
    Show answer

    Answer: A. Site, needle size, and time placed

    Recording time and site matters because IO devices are intended to be short-term. Also document how placement was confirmed.

62. What is the main reason the distal femur is less commonly used in adults?

    1. A. The femur contains no marrow in adults
    2. B. The femur is too fragile for an IO needle
    3. C. Thick soft tissue and unclear landmarks
    4. D. Femoral IO causes immediate fat embolism
    Show answer

    Answer: C. Thick soft tissue and unclear landmarks

    Adult thighs have abundant muscle and fat, making the distal femur unreliable.

63. A patient with an IO in the tibia complains of severe pain during a rapid pressure infusion despite lidocaine. A reasonable step is:

    1. A. Repeat lidocaine and slow the rate
    2. B. Raise the pressure to finish faster
    3. C. Switch to an oral analgesic instead
    4. D. Remove the IO and abandon the site
    Show answer

    Answer: A. Repeat lidocaine and slow the rate

    Protocols commonly allow a smaller repeat lidocaine dose for persistent infusion pain.

64. In an obese adult whose proximal tibial landmarks cannot be felt, which lower-limb IO site often has less overlying tissue?

    1. A. Distal femur, just above the kneecap
    2. B. Calcaneus, at the back of the heel bone
    3. C. Fibular head, just below the knee joint
    4. D. Distal tibia, near the medial malleolus
    Show answer

    Answer: D. Distal tibia, near the medial malleolus

    The distal tibia, on the flat medial surface just above the medial malleolus, usually has little soft tissue even in obese patients. The adult distal femur lies under thick muscle and fat, and the calcaneus and fibular head are not standard IO sites.

65. After return of spontaneous circulation in a patient with a tibial IO, the crew should:

    1. A. Keep using it and add an IV when feasible
    2. B. Remove it at once to prevent infection
    3. C. Stop drug therapy until a central line is in
    4. D. Pull it back 1 cm to improve flow
    Show answer

    Answer: A. Keep using it and add an IV when feasible

    A working IO remains a valid route after ROSC; keep it secured and in use, and add IV access when feasible so the IO can be removed within 24 hours. Removing it leaves no access, stopping drugs risks re-arrest, and pulling it back dislodges it.