Vascular Access

I. Venous Access

A.

Flow through a catheter is determined by Poiseuille's law:

where Q = flow in mL/min, r = radius, P = pressure gradient, and L = length. The best flow is obtained when dilute, warm (decreased viscosity) fluid is run through a short, wide catheter under pressure. The diameter of the catheter is the most important factor (Table 12-1).

B.

Access to the vascular system should be obtained en route to the hospital or coincident with the primary survey in a horizontal resuscitation scheme. An intravenous (IV) line should not be placed with a vascular injury located between the IV access and the heart. For example, if a hypotensive patient has a gunshot wound to the upper right chest, IV access in the right arm can exacerbate bleeding from a subclavian vein injury.

C.

Venous access is obtained in all trauma patients for initial blood sampling, fluid resuscitation, and administration of drugs.

D.

Venous access is usually best obtained peripherally before consideration is given to placement of a central line.

• Percutaneous
  • Preferentially, two large-bore (14 or 16 gauge) IV catheters should be placed in large arm veins (e.g., the antecubital fossa). Blood should be drawn before initiation of fluid resuscitation via the catheter, provided the catheter has not been placed proximal to an infusing IV line. Sterile technique should always be used. Most peripheral lines placed for resuscitation in the pre-hospital setting or in the emergency department should be removed within 24 to 48 hours. These catheter sites need to be monitored for complications, particularly cellulitis and phlebitis.
• Cutdown
  • Surgical cutdowns are required infrequently in trauma patients, but can be invaluable in instances of difficult IV access, particularly in children.
  • The correct technique for venous cutdown is essential for prompt, successful cannulation. Each cutdown site should be selected based on accessibility, vein size, and the urgency for venous access.
  • Venous cutdowns for trauma have a higher infection rate and these lines should be removed when alternative access is secured.
  • General technical principles
    • The cutdown site should be immobilized, prepared, and draped.
    • Appropriate light and instruments should be available.
    • Mosquito hemostats and a no. 11 blade are recommended. In the small veins (<2 mm), venous wall elevators and dilators can be useful.
    • After anesthetizing the skin with a local anesthetic, a transverse skin incision is made, after which the fat and subcutaneous tissue is spread

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      in a longitudinal direction (i.e., along the course of the vein). A second hemostat or forceps is frequently necessary to secure the vein while it is being mobilized for a distance of approximately 1 to 2 cm.

      TABLE 12-1 Flow Rates Through Commonly Used Catheters or Infusion Systems

      Level I or rapid-infusion system 1,500 mL/min (high-flow tubing under pressure) High-flow tubing* 250 mL/min Standard tubing* 165 mL/min 7 F percutaneous sheath* 165 mL/min (high-flow tubing) 12-inch, central venous* 65 mL/min (14 gauge) 12-inch, central venous* 35 mL/min (16 gauge) 12-inch, central venous* 20 mL/min (18 gauge) 1.5-inch angiocatheter* 75 mL/min (16 gauge) 1.5-inch angiocatheter* 60 mL/min (18 gauge) *Standard tubing with gravity flow at 1 m height.

    • Two silk sutures are then placed under the vein as slings, tying the distal, looping the proximal, and holding each on tension.
    • With distal retraction, a partial venotomy is made in the anterior wall of the vein, with the 11-blade scalpel in a transverse fashion.
    • The catheter is then placed through the venotomy and secured with the proximal suture.
    • Special techniques for very small veins:
      • Consider using magnifying glasses or loupes.
      • Place a proximal tourniquet.
      • Use a longitudinal rather than a transverse venotomy.
      • Small pediatric feeding tubes (size 3 French [F] or 5 F catheter) have a rounded tip that can bluntly dilate the vein and negotiate proximal venous placement.
    • The skin incision should be carefully closed and dressed as a surgical wound.
  • Cutdown sites. The saphenous vein is the preferred site for venous cut-down, with the arm veins as the secondary site.
    • Saphenous vein at the ankle
      • Location: 1 cm anterior and 1 cm proximal to the medial malleolus (Fig. 12-1)
      • Advantages
        • Performed at a location unencumbered by the rest of the resuscitation team
        • Low morbidity site
        • Safest site for the novice
      • Disadvantages
        • Small veins
        • Distal from the central circulation
        • Frequently inaccessible because of lower leg fractures, casts, splints, or military antishock trousers (MAST)
    • Proximal saphenous vein
      • Location: 5 cm inferior to the inguinal ligament and 5 cm medial to the femoral pulse (or 5 cm medial to the midpoint of the inguinal ligament in a pulseless patient) (Fig. 12-2). This is a transverse medial proximal thigh incision and not a groin incision. The greater saphenous vein is somewhat variable in location because of the amount of fat in this area of the leg.
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        Figure 12-1. Saphenous vein cutdown at the ankle. (From Moore EE, Eisman B, van Way CW III. Critical decisions in trauma. St Louis, Mo: Mosby; 1984, with permission.)

      • Technique. After completing a 1- to 2-inch incision in the skin and subcutaneous fat, gentle cephalad and caudal retraction will help expose the vein. If performing this procedure alone, a small, self-retaining retractor is helpful.
        In an adult, the vein can be identified rapidly by gentle palpation along the medial thigh fascia. The vein can frequently be mobilized longitudinally by spreading the hemostat under the vein while the index finger of the other hand is palpating the vein. The vein can then be immobilized over the hemostat, which can be left in place until the catheterization is complete.
        Large catheters (8 F to 10 F) can be placed for rapid flow into the iliac vein. Less commonly, a no. 10 or 12 pediatric nasogastric tube (with its rounded tip) can be introduced into the inferior vena cava via the saphenous vein because the rounded tip can facilitate transversing the saphenofemoral junction. However, flow rate can be reduced by the length of the tube.
      • Advantages
        • Large catheters can be placed quickly into the central circulation.
        • Access can be obtained without interfering with resuscitative activities at the head and torso.
        • Readily accessed in patients without a pulse.
        • Can be obtained intraoperatively.
        • Useful in experienced hands for infants and small children when no other access is obtainable.
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          Figure 12-2. The greater saphenous vein is accessed at a location 1 inch inferior to the inguinal ligament and 1 inch lateral to the pubic tubercle.

      • Disadvantages
        • Requires experience and familiarity with the anatomy.
        • Can be difficult in infants and children because of proximity to the femoral artery and vein.
        • An incision in proximity to the groin is required.
    • Antecubital region
      • Venous cutdown in the arm is best obtained at a site slightly proximal to the antecubital fossa. Although veins can be identified in the antecubital fossa, this area is frequently inaccessible because of (a) previous attempts to obtain venous access and (b) because inadvertent injury to the brachial artery and median nerve can occur. The preferred sites are the basilic vein (located 1 inch proximal and 1 inch medial to the medial epicondyle of the elbow) and the cephalic vein (located 1 inch superior and 1 inch medial to the lateral epicondyle of the humerus) (Fig. 12-3). The technique of venotomy and placement is similar to that described for other sites.
      • Advantage
        • Easy access, particularly when the patient is draped
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          Figure 12-3. Upper arm cutdown. (From Woodburne RT. Essentials of human anatomy. London: Oxford University Press; 1969:95, with permission.)

      • Disadvantages
        • More variable in location and somewhat more difficult than sap he-nous vein at the ankle
        • In proximity to other members of the team

E. Central access

Although central venous access was initially reserved for postre-suscitation stabilization, experience in many trauma centers has led to immediate central access for resuscitation of unstable trauma patients. With the advances of

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the Seldinger technique (guidewire through needle, followed by catheter over guidewire), central resuscitation catheters (8 F to 12 F) placed over a dilator sheath have become common practice. These catheters provide very high flow rates because of their large diameters (2.5—4.0 mm), which are especially useful for rapid-infusion devices.

• Site
  • Subclavian vein
    • Advantages
      • Easily accessible and provides immediate filling of the heart from the superior vena cava.
      • Allows measurement of the central venous pressure and access for subsequent placement of a pulmonary artery catheter.
      • The site is easily accessible from the head of the bed for the anesthesia team (supraclavicular approach).
    • Disadvantages
      • Initial resuscitation does not allow optimal positioning of the patient, such as the Trendelenburg position, placement of a roll between the shoulders, and rotation of the neck.
      • Proximity of the pleural space, great vessels, and cervical nerve structures increases the risk of complications: pneumothorax, arterial puncture, hemothorax; and injury to the thoracic duct, phrenic artery, or brachial plexus.
      • Radiologic confirmation of proper placement can be delayed.
      • In proximity to other members of team.
    • Technique (Fig. 12-4)
      • Ideally, the patient is placed in the Trendelenburg position with a roll between the shoulders, although this may not be possible in acute trauma resuscitation.
      • If a cervical collar is in place, the anterior portion must be removed and the neck immobilized, to allow finger access to palpate the jugular notch. The subclavian area is prepared, and skin and subcutaneous local anesthesia is administered, using the needle to localize the subclavian vein.
      • The access needle is then advanced beneath the clavicle, entering from lateral to medial under the middle third of the clavicle and aiming toward the index finger of the other hand, which is placed in the jugular notch of the sternum. The needle is advanced slowly, while hugging the undersurface of the clavicle and withdrawing on the syringe plunger until free blood flow is obtained.
      • The guidewire should not be advanced unless blood flows freely in the syringe. It is usually helpful to advance the needle approximately 1 mm after obtaining rapid flow in the syringe before advancing the guidewire. The guidewire should be advanced slowly in short intervals, with the index finger and thumb close to the hub of the needle. If the guidewire meets resistance, the needle and guidewire should be removed together to avoid shearing the guidewire on the access needle.
      • If the guidewire advances without resistance, the needle is removed, a small skin incision is made with the knife (11 blade), and the dilator and catheter sheath are advanced firmly but gently over the guidewire. Some portion of the guidewire should be visible and secured at all times.
      • It is not necessary to advance the dilator its entire length because once it is in the vein, the catheter sheath can be advanced over the guidewire, which will help prevent perforation of the superior vena cava during placement.
      • The ability to freely withdraw blood from the catheter sheath with gentle pressure should be ascertained before initiating IV flow.

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        Alternatively, free flow can be ensured by connecting the catheter to the IV delivery system and lowering the fluid bag toward the floor. If free backflow of blood is seen, IV fluids can be initiated. On occasion, the sheath will have to be withdrawn slightly to demonstrate blood flow.

        Figure 12-4. Approach to the subclavian and internal jugular veins. (From Moore EE, Eisman B, van Way CW III. Critical decisions in trauma. St Louis, Mo: Mosby; 1984:513, with permission.)

      • A chest x-ray should be performed to confirm placement and rule out complications.
    • Complications
      • Arterial puncture. When this occurs, the catheter should be withdrawn and digital pressure applied with the thumb below the clavicle and the index finger above the clavicle for a minimum of 5 minutes. Chest x-ray should be obtained to rule out a pleural effusion which would suggest bleeding.
      • Pneumothorax occurs in up to 5% of patients, even in experienced hands. Withdrawing air in the syringe can occur as a warning sign, but is present in only 20% of the cases in which pneumothorax occurs.
      • Catheter malplacement into the internal jugular vein. As long as free flow occurs, this catheter can still be used for resuscitation but should be repositioned at the first opportunity, which can usually be done without the need for an additional puncture.

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        Hypertonic solutions should not be infused until proper placement of the catheter tip in the superior vena cava is confirmed.
      • Exit from the superior vena cava can result in life-threatening hemorrhage and is usually recognized by signs and symptoms of hemothorax, usually occurring in the opposite side of the chest.
      • Dysrhythmia, particularly if the guidewire is advanced into the heart. In these cases, the guidewire should be slightly withdrawn. If the dysrhythmia does not resolve, the wire should be further withdrawn. Caution should be taken in patients with a known left bundle branch block because guidewire placement can precipitate a right bundle branch block leading to complete heart block requiring pacing.
    • Subclavian site selection
      • No difference appears to exist in the success or complication rate between right and left subclavian catheter placement. This is more of an issue of judgment, comfort, and experience for the physician placing the catheter. It has been suggested that if a chest injury requiring a chest tube has already been identified, the catheter should be selectively placed on that side to avoid the possibility of an iatrogenic contralateral pneumothorax or injury. This intuitive approach has never been substantiated in the literature. More commonly, selection of the subclavian site is a practical determination based on resuscitative activities in progress on either side of the patient. For example, if a chest tube is being placed on the right side, it is much easier to simultaneously place a subclavian catheter on the left side.
  • Internal jugular vein. In blunt trauma, the acute use of an internal jugular catheter is limited by the cervical collar, inability to properly position the neck, or inaccessibility to the head of the patient because of the airway team. However, in penetrating trauma remote from the neck, this approach has been found useful.
    • Technique
      • The Seldinger technique, with the precautions noted previously for the subclavian vein, is the same. Most clinicians use the anterior approach through the supraclavicular triangle between the heads of the sternocleidomastoid muscle toward the ipsilateral nipple at an angle 45 degrees from the horizontal.
    • Advantage
      • Better access from the head when the patient is draped or having other resuscitative activity at the chest level
    • Disadvantages
      • Inability to position the neck and the presence of a cervical collar
      • Difficult to immobilize and maintain sterile dressing
      • Proximity of other members of team
    • Complications
      • Same as those for subclavian vein catheter (carotid artery injury rather than subclavian artery)
  • Femoral vein
    • Technique
      • The Seldinger technique, with placement of large-bore catheters through the femoral vein, is used frequently in trauma resuscitation. The femoral vein is located approximately 1 cm medial to the femoral artery just at or below the inguinal ligament.
      • It is generally easier for left-handed operators to access the patient's left femoral vein and vice versa.
    • Advantages
      • Easy access, particularly when other resuscitative efforts are occurring at the head or torso
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      • Lower acute morbidity than the subclavian or internal jugular approach
    • Disadvantages
      • Difficult to locate the vein in a pulseless patient
      • Does not guarantee high central flow in patients with intraabdomi-nal or pelvic vascular injury
      • Clot can develop at the puncture (frequently non-occlusive)

F. Intraosseous access

• In children who are aged 6 years or younger, intraosseous access should be established if reliable venous access cannot be established percutaneously after two attempts. It should be used for the initial resuscitation and should be removed when the child has been stabilized and alternative access has been obtained.
• In general, any IV drug or fluid required during the resuscitation of children can be safely administered by the intraosseous route. Fluids generally need to be administered under pressure. Specifically designed needles (modified bone marrow aspiration needles) have been developed for this purpose.
  Sites
  • The flat anteromedial surface of the proximal tibia, approximately 1 to 3 cm below the tibial tuberosity, is the preferred site for infants and children, because the marrow cavity in this location is very large and the potential for injury to adjacent tissues is minimal (Fig. 12-5).
  • The anterior surface of the distal tibia, approximately 2 cm above the medial malleolus, is the second preferred site.
  • The anterior surface of the distal femur has also been used.
• Technique
  • Identify the insertion site and prepare and drape in a sterile fashion.
  • Infiltrate skin and subcutaneous with local anesthesia.
  • Check the needle to ensure that the bevels of the outer needle and internal stylet are properly aligned.
  • Stabilize the extremity without placing your hand behind the insertion site.
  • Place the needle through the skin over the identified site, advancing the needle through the bony cortex, directing the needle perpendicular (90 degrees

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    to the long axis of the bone). Use a gentle but firm twisting or drilling motion.

    Figure 12-5. Intraosseous cannulation.

  • Stop advancing the needle when a sudden decrease in resistance to forward motion of the needle is felt. It is usually possible to aspirate bone marrow at this point. Aspiration of marrow should be followed by irrigation to prevent marrow obstructing the needle.
  • Unscrew the cap, remove the stylet, and stabilize the needle. A small inverted medicine cup (with the bottom removed) provides protection for the needle when placed over the site and taped in place.
  • Inject 10 mL of normal saline solution through the needle and check for signs of increased resistance to injection, increased circumference of the soft tissues of the calf, or increased firmness of the tissue.
  • If the test injection is successful, begin infusion.
  • If the test injection is unsuccessful, remove the needle and attempt the procedure on the other leg.
• Complications are rare but include local cellulitis and abscess, osteomyelitis, fracture of the bone, pressure necrosis of the skin, compartment syndrome, epiphyseal plate injury, and hematoma.

II. Arterial Access

After the patient has been stabilized or during stabilization, insertion of an arterial catheter allows continuous blood pressure monitoring and frequent blood sampling. In general, the arterial line should be removed when the patient no longer requires continuous pressure monitoring and when frequent blood sampling is unnecessary.

A. Sites

• The radial artery is the preferred site for arterial catheter placement, because the complication rate is lower than other sites. It has been suggested that the Allen test (simultaneous compression of the radial and ulnar arteries, followed by release of the ulnar artery, looking for a flush of perfusion in the hand) be performed before radial artery line puncture. This is not commonly done in most centers because the incidence of distal ischemia is rare, especially in young patients. However, this test should be considered in the elderly, especially under more elective conditions.
• The femoral artery is a common line in trauma patients, but requires a somewhat longer catheter. The incidence of infection and distal ischemia is no greater than a radial artery catheter when used in initial resuscitation. However, after stabilization, these lines should be removed because the complication rate increases with time and the location can limit the mobility of the patient.
• The dorsalis pedis artery is a more difficult site for percutaneous placement and is difficult to immobilize. This site is more useful in an elective environment, especially in younger patients with limited arterial access.
• The axillary artery. Axillary arterial lines have been reported to be very successful in experienced hands in the elective intensive care unit (ICU) environment with low complication rates. They have not been used routinely as part of early resuscitation.
• The brachial artery should not be used because it is an end artery with a relatively narrow lumen and a higher incidence of ischemic complications.

B. Technique

• Immobilize the extremity and identify the pulse. Doppler or vascular access ultrasound can be helpful in this regard.
• Prepare and drape the area in a sterile fashion.
• Anesthetize the skin with a local anesthetic, even in the unconscious patient, to help reduce vasospasm.
• A variety of arterial catheters have been developed and are typically 18 or 20 gauge for the radial artery and 16 or 18 gauge for the femoral artery for an adult. The incidence of thrombosis is related to the diameter of the catheter relative to the size of the artery.
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• Using the catheter-over-the-needle technique, advance the needle at a 30- to 45-degree angle through the skin at the site of maximal pulsation.
• Two acceptable techniques have been described for the catheter-over-the-needle approach.
  • The catheter and needle can be passed through both walls of the artery to transfix it, after which the needle is withdrawn, followed by slow withdrawal of the catheter until a pulsatile flow of blood is obtained. The catheter is then advanced slowly through the lumen of the artery. The catheter should not be advanced unless a pulsatile flow extends beyond the hub of the needle.
  • A second technique is to puncture only the anterior wall of the artery, after which the catheter is slowly advanced until blood appears in the needle. The needle is then lowered to a nearly 10-degree angle from the horizontal, and the catheter is slowly advanced over the tip of the needle into the lumen of the artery.
  • Both of these techniques can be facilitated by using a guidewire. The modified Seldinger technique uses a guidewire passed through a needle, followed by catheter placement over a guidewire. Commercial catheters with a self-contained guidewire are also available.
• The catheter is connected to a continuous infusion of heparinized saline solution (the heparin can be withheld in patients with coagulopathy or head injury).
• The catheter should be sewn into place and a sterile dressing applied.
• Cutdown for arterial access is sometimes necessary. This is applicable only for the radial and dorsalis pedis areas. In general, a longitudinal skin incision is more useful than the transverse skin incision. The infection rate for an arterial cutdown site is high, and this site should be used only when no alternative exists. Small, curved forceps and vessel dilators (contained in cardiac catheter-ization kits) facilitate a successful arterial cutdown.

C.

The incidence of complications from arterial access are low but can be serious. They include hematoma, cellulitis or abscess, systemic sepsis, ischemia, emboliza-tion, malposition, and nerve injury. The incidence of arterial thrombosis is proportional to the size of the catheter and duration of cannulation.

III. Initial Fluid Resuscitation

A.

Details of fluid resuscitation are contained in Chapters 5, 10, 39, and 42.

B.

Injury can result in a decrease in red blood cell mass and intravascular volume, with a reduction in cellular oxygen and nutrient delivery. This can worsen because of the increased metabolic demands of trauma. The goal of initial fluid resuscitation is to restore effective circulating blood volume and avoid pulmonary and cerebral complications of fluid overload.

C.

Key points in initial fluid resuscitation include:

• Establish access in at least two venous sites. Examine all prehospital lines for catheter size, location, and function. Catheters in the back of the hand wrapped in gauze are commonly dislodged or infiltrated.
• Calculate the prehospital fluids as part of the initial resuscitation.
• Infuse warm fluid (40°C). Crystalloids (Ringer's lactate or normal saline solution) are the initial fluid of choice for most trauma patients.
• In hemodynamically normal patients without obvious injury, limit the initial fluid resuscitation (first hour) to 1 L in adults.
• In normotensive adults with tachycardia or obvious sources of blood loss, infuse 2 L of crystalloid as rapidly as possible. (Use some caution in this patient category in cases of an associated head injury.)
• In hypotensive adults who respond to initial fluid resuscitation, continue maintenance crystalloids (100–150 mL/h) after the initial 2 L.
• In hypotensive adults who are transient or nonresponders to initial fluid resuscitation, infuse blood as early as possible to avoid profound hemodilu-tion from excessive crystalloid.
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• Blood component therapy (fresh frozen plasma and platelets) as part of initial fluid resuscitation should be given when clinical or laboratory evidence is seen of coagulopathy or in accord with the institutional massive transfusion protocol. Cryoprecipitate is usually reserved for documented hypofibrinogenemia. Prophylactic component therapy as part of initial fluid resuscitation has not been shown to be of value.
• Hypotensive pediatric patients should have crystalloid infusion using boluses of 20 mL/kg, which can be repeated once. Transient or nonresponders should be given blood at 10 mL/kg.
• Rapid-infusion devices provide excellent tools for fluid resuscitation. Warmed fluids, including blood, can be infused at rates of up to 1.5 to 2.0 L/min. Care must be taken to monitor blood pressure, pulse, airway pressures, and arterial oxygen saturation to avoid inadvertent fluid overload.
• Hypertonic saline solution has been shown to improve outcome in selected patients with head or thermal injury. Institutional protocols should be developed for safe and effective use.

Axioms

• Most trauma patients can be resuscitated with peripheral venous access only.
• Short, wide IV catheters and tubing are preferred.
• The technology for central venous access has lowered the threshold for placement of rapid-infusion catheters for resuscitation.
• Placement of large-bore catheters through central access during acute resuscitation should be done by experienced personnel, limiting the advancement of the dilator to avoid mediastinal or intrapleural hemorrhage, which can be fatal.
• Arterial lines can be placed as part of the early resuscitation to afford monitoring and frequent blood sampling. However, this can be delayed until the patient is in the OR or the ICU, using other noninvasive monitoring and sampling techniques in the resuscitation area.
• A venous line should not be placed at a site such that a penetrating wound is between the line and the heart. If the trajectory of a thoracic wound is not certain, place lines above and below the diaphragm.
• Establishing an IV cutdown on a small vein can be difficult. Light, loupes, and appropriate instrumentation and catheters are essential for success.
• Initial fluid resuscitation should be tailored to avoid the pulmonary and cerebral complications of fluid overload.