Chapter 3 Emergency and Critical Care Techniques and Nutrition

Shane W. Bateman, C. Anthony Buffington, Cheryl Holloway

This chapter describes commonly used techniques in emergency and critical care medicine. See appropriate chapters for information about diseases that require critical care.

INTRAVENOUS CATHETERIZATION BY CUTDOWN

Indications

Key Point

Venous access is required in every emergency situation.

Perform venous cutdown when percutaneous venous catheterization has been unsuccessful after one or two attempts (depending on the urgency with which access is required). Nonurgent venous cutdown can also be performed when numerous percutaneous catheterization attempts have resulted in severe peripheral hematoma formation or thrombophlebitis.

Contraindications

Relative contraindications include severe hemostatic dysfunction. However, occasionally such patients require IV catheterization, necessitating an easily compressible location as the best choice for a cutdown procedure.

Objective

Obtain vascular access for administration of fluid and drugs.

Technique

1. When the patient is semicomatose or moribund, local anesthesia is not required. Otherwise, infiltrate small amounts of local anesthetic into the aseptically prepared skin site.

2. In general, the lateral saphenous (canine) or medial saphenous (feline) are easier to approach than the cephalic veins. Jugular cutdown can also be performed with the same technique, but the vein is deeper and may be more troublesome for inexperienced surgeons to find.

3. After aseptic skin preparation and use of aseptic technique, identify the vessel. In many situations the vessel may not be visible even when occluded, so the anatomy of the vessel is important to understand.

4. Place the scalpel blade gently on the skin over the vessel and, without cutting the skin but maintaining skin contact with the blade, pull the skin laterally to the vessel (Fig. 3-1).

5. Incise approximately 1 to 1.5 inches parallel to the vessel.

6. Allow the skin to retract back into place over the vessel.

7. The bluish hue of the vessel should be obvious if the incision was made in a correct location. Move the skin to attempt to identify the vessel if it is not immediately obvious. To differentiate the vessel from underlying muscle bellies, the vessel should blanch with minimal digital pressure; muscle bellies will not.

8. Hold the iris scissors with the thumb and index finger in the finger rings with the tips of the scissors pointing across the palm of your hand, not extending out from the fingers. This allows the shaft of the scissors to be perpendicular to the patient and the vessel.

9. Place the tips of the scissors as close to the vessel wall as possible, apply gentle pressure to the tissue, and extend the blades maximally, bluntly dissecting the fascia from the vessel wall (Fig. 3-2A).

10. Repeat this procedure on both sides of the vessel wall until the vessel is freed from its fascial attachments and the mosquito hemostat can be placed under the vessel. Take care not to place the tips of the blades on the vessel itself. In addition, if small side branches of the vessel are present, choose a more proximal or distal location.

11. Pull a loop of suture ventrally underneath the vessel to exteriorize and serve as a manipulator to allow positioning of the vessel for catheterization.

12. Examine the vessel for remnants of fascia. It is easy to catheterize one of these fascial planes by mistake and think that you are in the vessel lumen. Strip the vessel of any remaining fascia by gently using one arm of the Adson thumb forceps.

13. Catheterize the vessel using the suture as a handle to manipulate the vessel into an appropriate position (Fig. 3-2B).

14. It is easy to puncture both sides of the vessel wall, so prior to advancing the catheter, verify that the metal of the stylet cannot be seen underneath or beside the vessel wall by gently moving the catheter.

15. Flush the IV catheter to confirm successful catheterization.

16. Remove the loop of suture, connect IV fluids to the catheter, suture or staple the skin with the catheter exiting from the suture line, and secure the catheter to the skin with the normal taping method.

Figure 3-1 Position of scalpel and skin for skin incision.

Figure 3-2 A, Blunt dissection of the vessel using sharp/sharp scissors. B, Catheterization of vessel using stay sutrue.

INTRAOSSEOUS ACCESS FOR FLUID ADMINISTRATION

Indications

Intraosseous access is typically utilized only in neonatal or pediatric patients because of the small size of their peripheral vessels.

Contraindications

Key Point

Do not use intraosseous access where severe tissue trauma exists or in areas of potentially infectious dermatitis.

Equipment

• Local anesthetic

• 22- to 20-gauge, 1- to 1.5-inch spinal needle (with stylet)

• Commercial intraosseous catheter (optional)

Technique

1. Aseptically prepare the skin over the appropriate site. In general, the intertrochanteric fossa or the tibial crest is the easiest site to gain access (Fig. 3-3).

2. Infuse a small quantity of local anesthetic into the periosteum and the skin surrounding the site. Be cautious that the volume administered is not in the toxic range for the size of the animal. Lidocaine can be diluted to 1% to prevent toxicity if necessary.

3. Using aseptic technique, identify the site of needle insertion into the appropriate long bone (femur or tibia) and palpate firmly to identify the appropriate direction and angle of needle advancement. Direct the needle as straight as possible down the marrow cavity of the shaft of the long bone.

4. Advance the needle using gentle but steady forward pressure as you slowly twirl the shaft of the needle back and forth.

5. Once the needle is firmly seated into the bone, remove the stylet and attempt to aspirate through the needle. Ability to aspirate bloody fluid (bone marrow) generally indicates successful placement. If awake, animals will often object to aspiration as they would for bone marrow aspiration.

6. Gently flush the needle with isotonic fluid and gently palpate around the long bone for accumulation of fluid. If fluid accumulates outside the bone, then the needle has penetrated the cortex and must be repositioned into the marrow cavity.

7. If successfully placed, attach the IV line to the needle (a luer lock tip assists in prevention of accidental disconnection). Carefully bandage the limb and exposed needle to minimize movement.

Figure 3-3 Anatomic locations for intraosseous access.

Complications

Poor needle placement can result in inappropriate needle tip placement into the cortex or outside the cortex. Repositioning of the needle usually results in success. Patients that are moving vigorously or traumatizing the needle may shift the tip to an inappropriate location, allowing fluid accumulation in the subcutaneous tissue. Regular monitoring of the limb and needle are warranted to detect this complication.

ARTERIAL SAMPLING FOR BLOOD GAS ANALYSIS

Indications

Collection of an arterial blood sample is often helpful in assessing respiratory function and effective gas exchange. Analysis of a blood gas for acid-base status is more meaningful when venous blood is utilized.

Contraindications

Presence of a severe coagulopathy is a relative contraindication. In general, with firm direct pressure for prolonged periods, significant blood loss is not a concern. The sample is most easily obtained when the patient is in lateral recumbency; thus observe patients with respiratory compromise carefully for worsening of respiratory distress during the procedure and give supplemental oxygen as required.

Objectives

• Obtain arterial blood for blood gas analysis

• Prevent hemorrhage

Equipment

Use either of the following:

• Dry heparin blood gas syringe

• A heparinized regular syringe

Technique

1. If no commercially available dry heparin blood gas syringes are available, heparinize a regular syringe by withdrawing liquid heparin into the syringe so that the insides of the syringe barrel are in contact with the heparin. Depress the syringe plunger to extrude the liquid heparin out of the needle. A small quantity of liquid heparin should remain in the syringe hub. Place a new needle onto the syringe prior to puncturing the skin.

2. The two most commonly utilized sites for arterial sampling are the femoral artery medial to the femur in the inguinal region (Fig. 3-4A) and the dorsal metatarsal artery medial to midline and distal to the tarsus joint (Fig. 3-4B).

3. Hold the tips of the index and middle fingers of the nondominant hand perpendicular to the artery but parallel to the long axis of the patient and gently palpate the region until the pulsation of the artery can be felt underneath both finger tips. Excessive pressure will often occlude the artery and prevent successful palpation of the pulsation.

4. Gently stabilize the artery and skin between the fingers of the nondominant hand.

5. Hold the sampling syringe with the dominant hand. Place the needle between the fingers over the artery and advance slowly at an acute angle (45 degrees or greater for the dorsal metatarsal artery, slightly less than 90 degrees for the femoral artery).

6. Observe the hub of the needle carefully for a blood flashback to “jump” into the hub. Frequently, pulsations can be observed if the patient’s blood pressure is high enough. Self-filling blood gas syringes should fill rapidly if the pressure is normal. Withdraw the sample volume if a conventional syringe is being utilized. Slow flashbacks, lack of observable pulsations, color of the blood sample, slow filling of self-filling syringes, and the blood gas results may all indicate that the sample is venous or mixed rather than a pure arterial sample.

7. Place gentle but firm pressure over the sampling site for 3 to 5 minutes, then observe for an additional 30 to 60 seconds to ensure that the puncture site has sealed to prevent hematoma formation.

Figure 3-4 A, Femoral artery puncture. B, Dorsal metatarsal artery puncture.

Complications

Hematoma formation is infrequent and can be prevented by applying pressure for an appropriate duration. Avoid accidental puncture of the nerve that courses parallel to the artery; puncture can cause a painful reaction.

NASAL CATHETER PLACEMENT

Indications

Patients require supplemental oxygen or enteral feeding.

Objectives

• Provide oxygen therapy using a nasal catheter

• Provide nutritional supplementation using a nasogastric tube

Technique

1. Install several drops of local anesthetic into the nostril with the patient’s head tipped up slightly; allow several minutes to reach peak effect.

2. Premeasure the catheter to (a) the last rib for nasogastric tube, (b) the base of the heart for nasoesophageal tube, or (c) the junction of the zygomatic arch and the cranial edge of the ramus of the mandible for nasal oxygen.

3. Restrain the patient with the head tipped slightly up and place the tip of the catheter gently into the nostril.

4. Use the thumb of the nondominant hand to push gently up on the nasal philtrum. With the index finger of the same hand, gently squeeze against the thumb from the top of the nasal planum (Fig. 3-5).

5. Advance the catheter quickly and gently, forcing the tube in a ventral and medial direction into the ventral meatus. The patient will often retract away from you, so release your advancing fingers immediately after you have advanced the tube. This is a similar motion to holding and throwing a dart.

6. Advance the catheter with repetitive motions until the premeasured catheter length has been inserted. If placing a nasal oxygen cannula, advance the tube past the nasopharynx if possible to confirm placement into the ventral meatus, then pull back to the premeasured length. Tubes that will not advance past the nasopharynx may be in the dorsal meatus and should be repositioned.

7. Place a small length of tape to the dry tube where it exits the nostril.

8. Place a simple interrupted suture at the ventromedial corner of the nostril. Place a finger trap suture pattern over the tape on the tube to secure the tube to the nostril (Fig. 3-6A–D). Tie multiple knots to complete the finger trap.

9. Place a second simple interrupted suture to the ventrolateral corner of the nostril at the mucocutaneous junction using the remaining ends of the suture to further secure the tube from accidental removal (Fig. 3-6C).

10. Use skin staples to attach the end of the tube to the patient’s face, generally either on the side of the face or up the center of the face between the eyes and to the top of the head (Fig. 3-6D).

11. Verify feeding tube placement with radiographs or capnographic confirmation.

Figure 3-5 Positioning for placement of nasal catheter.

Figure 3-6 Finger trap suture pattern.

Complications

Occasionally the tube will not advance past the nasopharynx (even through the ventral meatus) because of anatomical conformation in individual animals. In such patients, pass the tube through the opposite nasal passage. In addition, feeding tubes may be inadvertently passed into the trachea and airway, especially in sedated, anesthetized, or obtunded patients. Confirm placement using radiography or capnography. Feeding tubes can also be vomited back up the esophagus and chewed off by the patient, so closely observe patients with nasal feeding tubes.

EMERGENCY TEMPORARY TRACHEOSTOMY

Indications

Patient has life-threatening upper airway obstruction (proximal to the cervical trachea) and cannot be intubated with an endotracheal tube.

Contraindications

Airway obstruction distal to the site of tracheostomy. Severe coagulopathy is a relative contraindication, but this can be treated with transfusion component support and direct pressure.

Objectives

• Establish a patent airway

• Maintain the patent airway by frequently cleaning or replacing the tracheostomy tube

Equipment

• Scalpel handle and #10 or #15 blade

• Mayo scissors

• Large, curved Kelly or Carmalt hemostat

• Tracheostomy tube

• Monofilament suture material appropriate to patient

Technique

1. Position the patient in dorsal recumbency with the head extended slightly off and over the edge of the table or with the neck over a rolled towel or sandbag.

2. Make one attempt to insert a large over-the-needle peripheral IV catheter into the trachea at the base of the neck close to the thoracic inlet to provide oxygen to the patient while final preparations are made.

3. Rapidly clip and aseptically prepared the skin.

4. The patient will need rapid IV anesthesia for the procedure unless it is moribund.

5. Incise the skin from the larynx to the thoracic inlet.

6. Bluntly force the closed tips of Mayo scissors into the first tissue plane, open and insert one tip into the tissue plane created, then incise the tissue plane to each end of the incision. Attempt to use the sharp edges of the scissors to cut by advancing with the blades open rather than “scissoring” through the tissue.

7. Incise the sternohyoideus muscles (strap muscles) in a similar way, exposing the trachea.

8. Identify the neurovascular bundle on each side and bluntly insert a hemostat through the fascia dorsal to the trachea, allowing it to be elevated into the surgical incision.

9. Do not damage the vessels overlying the trachea.

10. Depending on the experience and skill of the surgeon, two approaches to incising the trachea are possible:

a. If the surgeon feels comfortable and excellent surgical precision is possible, incise the trachea transversely “between” two rings in the mid cervical trachea (Fig. 3-7). Extend the incision over the ventral two thirds of the circumference of the trachea. Do not incise into the dorsal tracheal membrane.

b. Alternatively, if the surgeon is less comfortable and a lesser degree of surgical precision is likely, incise longitudinally “through” several rings (Fig. 3-8). Holding the scalpel upside down and gripping the blade carefully to allow only 10 to 15 mm of blade to be exposed, incise approximately four tracheal rings beginning with ring 3 and continuing through ring 6 distal to the larynx.

11. Direct oxygen toward the incision.

12. Place stay sutures (3-0 or 4-0 silk) in the edges of the tracheal incision. If a transverse incision was made, place stay sutures in the ventral-most aspect of the trachea and around the first proximal and first distal ring. If a longitudinal incision was made, place stay sutures around two adjacent rings, approximately 3 to 5 mm from the tracheal incision and encompassing 2 tracheal rings on both sides of the incision. Leave the suture ends long.

13. Insert the tracheostomy tube into the trachea. Several types of specialized tracheostomy tubes are commercially available. Each has advantages and disadvantages. A simple tracheostomy tube can also be easily constructed from an endotracheal tube (Fig. 3-9).

14. The most critical aspect of tube placement is the size and fit of the tube. If the tube exerts circumferential pressure on the tracheal mucosal, then significant pressure necrosis, scarring, or fibrotic web formation are more likely to occur as a complications. Choose a tube that fits loosely in the trachea with no major points of mucosal pressure. Do not inflate the cuff unless positive pressure ventilation is required.

15. Suture the skin edges to allow easy access to the tracheal incision when the tube needs to be changed.

Figure 3-7 Between-the-rings tracheostomy with stay suture placement.

Figure 3-8 Through-the-rings tracheostomy with stay suture placement.

Figure 3-9 Tracheostomy tube construction from endotracheal tube.

Postoperative Care and Complications

• Clean or replace the tube as necessary to maintain patency.

• Clean the “dirty tube” and allow it to soak in an appropriate and safe antimicrobial solution, then rinse carefully with sterile saline prior to the next tube exchange.

• Do not apply suction to the tube.

• Keep the animal well hydrated.

• Protect the skin around the tube with petrolatum (Vaseline).

If possible, use tracheostomy heat and moisture exchange devices (HME) to maintain airway humidification and thus decrease viscosity of secretions. These devices add a small amount of increased resistance that contributes to the work of breathing. In patients with marginal muscle strength, this may be significant and lead to a vicious cycle of hyperthermia and increased work of breathing.

Monitor the patient’s temperature regularly. Routine administration of saline into the tracheostomy site is not recommended. A poorly fitting tube and inappropriate inflation of the cuff are the most common cause of fibrosis and web formation as a long-term complication.

ABDOMINOCENTESIS

Indications

Physical examination or radiographic evaluation indicates moderate quantities of peritoneal effusion, and cytological or chemical analysis of the fluid will assist in the diagnostic process.

Contraindications

Severe coagulopathy is a relative contraindication depending on the value or benefit of obtaining a fluid sample. Relative contraindications to use of a blind technique include a large abdominal mass; significant organomegaly, particularly of a vascular organ such as the spleen, liver, or kidney; or distension of a hollow viscus such as bowel or uterus. Consider ultrasonographic guidance if available.

Objectives

• Aseptically obtain fluid from the abdominal cavity for analysis and culture

• Avoid trauma to abdominal organs

Equipment

• 22- to 20-gauge, 1- to 1.5-inch needle and syringe appropriate to patient size (e.g., 3- to 12-ml syringe)

Technique

1. If possible, allow the patient to stand or be positioned in sternal recumbency to allow access to the most dependent site on the abdomen. Alternatively, place the patient in left lateral or dorsal recumbency.

2. The goal of the patient position and of the location and direction of the abdominocentesis attempt is to avoid the spleen, thus preventing hemorrhage that will contaminate the sample.

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Tags: Saunders Manual of Small Animal Practice

Aug 27, 2016 | Posted by admin in SMALL ANIMAL | Comments Off

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