Chapter 3-03: Approaches and Chief Complaints in Critical Care Medicine

APPROACH TO VASCULAR ACCESS

• Determinants of flow rate:

  • - Catheter radius (larger radius → larger area → higher flows)

    • Small changes in radius have relatively large impacts on flow rates

    • Measured as French (Fr) vs. gauge

      • - Two scales that reflect the diameter and therefore size of the lumen

        • Fr: Larger Fr catheters (i.e., higher number) have LARGER diameters

        • Gauge: Larger gauge catheters (i.e., higher numbers) have SMALLER diameters

  • - Length of catheter (shorter catheter → higher flows)

  • - Number of lumens (fewer lumens → higher flows)

  • - Pressure difference (larger changes in pressure → higher flows)

    • Augment by using pressure bags, manually squeezing the bag, or increasing vertical distance between the fluid bag and the patient

  • - Viscosity: More viscous products (i.e., blood) will flow more slowly

• Venous site selection:

  • - Internal jugular (most common)

    • Pros: High placement success rate, low risk of pneumothorax with ultrasound guidance

    • Cons: Possible higher rate of bloodstream infections compared to subclavian

  • - Subclavian

    • Pros: Likely lowest rates of bloodstream infections of the three sites

    • Cons: Highest rate of pneumothorax, decreased placement success rate with less experienced providers

  • - Femoral

    • Pros: High placement success rate, no pneumothorax risk. Often used in trauma or codes given site is away from intubation or CPR

    • Cons: Possible higher rate of bloodstream infections given location, limits patient mobility

• Vascular access options for common patient scenarios:

  • - Most patients in the ICU and medical wards:

    • Angiocath for peripheral venous access: Various sizes, including 14G, 16G, 18G, 20G, 22G

  • - ICU patient with septic shock requiring vasopressors, multiple IV antibiotics, and other medications:

    • Triple-lumen central venous catheter: Contains three lumens which are 1 × 16G and 2 × 18G; catheter length from 15–30 cm selected based on patient size and insertion location

  • - Gastrointestinal bleed requiring aggressive and rapid transfusion of multiple blood products:

    • MULTIPLE large-bore (often 16G or 18G) peripheral IVs

    • Alternative is an introducer or cordis, which are short catheters with large diameters, most commonly 8 Fr

  • - Code blue → PEA arrest in a patient without IV access:

    • Intraosseous (IO) access into a long bone (often tibia) with a 15G tibial needle enabling rapid infusions; short-term use until other access can be obtained

  • - Patient with endocarditis or osteomyelitis requiring long-term administration of antibiotics:

    • Peripherally inserted central catheter (PICC): Long catheters ranging from 30–60 cm in length; single-, double-, or triple-lumen options, with lumens being 4–5 Fr or 18G

APPROACH TO LACTIC ACIDOSIS

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