Medical Pharmacology Chapter 43:  Adult Cardiac Procedures

Coexisting Disease and Adult Cardiac Surgical Procedures:  Anesthesia Implications

• Difficult airway/intubation

  • Expectations based on patient history:

    • Obstructive sleep apnea

    • Ankylosing spondylitis

      • Progressive form of spinal arthritis, leading to the spontaneous vertebral fusion

        • May occur alone or may be associated with psoriasis, inflammatory bowel disease.

      • Ankylosing spondylitis patients tend to develop progressive kyphotic deformity, forward spinal bending-which can be ultimately extreme, forcing patients even to walk backwards, looking through their legs, to see where they're going

    •  Previous cervical spine fusion

  •  Problems to be anticipated associated with difficult airway/intubation

    • Normal cardiac surgical case: significant narcotic and long acting-nondepolarizing muscle relaxants drugs (use of these agents prevent "allowing the patient to wake-up" in the event of intubation difficulty)

    •  Awake intubation:-- many undesirable effects, particularly in cardiac patients:

      1.  Induced hypertension

      2.  Induced tachycardia

      3.  Discomfort

  • Solutions: modification of anesthetic plan

    • Step 1: Previous history {evaluate prior anesthetic records for airway, laryngoscopy, intubation information}

    • Alternative approaches

      1.  Brief "awake look" with laryngoscope following or oropharynx topical anesthesia

      2.  Anesthetic induction without using long-acting muscle relaxants and narcotics until verification that intubation and ventilation is possible

      3.  Awake fiberoptic intubation following topical anesthesia to the airway

         • Note that if awake fiberoptic intubation is performed, after the patient is anesthetized, documentation by direct laryngoscopy should be obtained as a basis for possible future general anesthesia requirements

         • Communication of the patient's difficult airway/intubation  must be provided to those responsible for postoperative management

• Full Stomach or gastroesophageal reflux

  • Unusual for a patient to be considered " full stomach" for an elective cardiac procedure

  • Patients at risk:

    •  Patients arriving for cardiac transplantation may not have been "NPO"

    •  Patients arriving for surgery from cardiac catherization on emergent basis

    •  Patients with delayed gastric emptying associated with:

      1.  Diabetes

      2.  Preoperative anxiety and stress

      3.  Certain medications e.g.  opioids

Adapted from Table 49-9, Shanewise, JS and Hug, Jr., CC, Anesthesia for Adult Cardiac Surgery, in Anesthesia, 5th edition,vol 2, (Miller, R.D, editor; consulting editors, Cucchiara, RF, Miller, Jr.,ED, Reves, JG, Roizen, MF and Savarese, JJ) Churchill Livingston, a Division of Harcourt Brace and Company, Philadelphia, p 1759, 2000.

•  Management of gastroesophageal reflux/hiatal hernia patients

  •  Preoperative drugs: metoclopramide (Reglan), H₂ antagonists, sodium citrate

  •  Cricoid cartilage pressure

  •  Rapid sequence induction/intubation

  •  Awake fiber-optic intubation

• Renal Disease and Cardiac Surgery

  • Factors associated with cardiac surgery which may adversely affect renal function:

    •  Angiographic dye, used during cardiac catherization: worsening renal insufficiency

    •  Vasopressor agents and abnormal circulation associated with bypass instrumentation: adverse effect on renal perfusion

    •  Surgical field suction use: adversely affect renal function secondary to hemolysis and increased serum free hemoglobin

  • Management of patients with renal disease

    •  Anemia: patients may be anemic, preoperatively, even with erythropoietin (Epogen, Procrit) administration

    • Hypovolemia: preoperative dialysis may cause the patient to be relatively hypovolemic -- special precautions for the dialysis patient

      •   Dialysis site care:

        • Do not position intravenous or arterial catheters or BP cuffs at dialysis site

        • Ensure that the dialysis site is protected during surgery

        • Verify dialysis site patency pre-and postoperatively

        • Note that a patient with arteriovenous fistula will have lower diastolic pressure and higher cardiac output-- also note that mixed venous O₂ saturation is affected, since it contains arterial blood shown to through fistula

    •   Fluid and hematocrit balance:

      • Fluid overload +anemia +coagulopathy may occur by the end of the case without careful attention to fluid/hematocrit balance

      • Avoid extra crystalloid fluids

      • Potassium balance critical:

        •  Cardioplegia and each unit of blood transfusion = potassium load

        •  Postoperative potassium removal requires exchange-resin enema or hemodialysis {serum potassium may be reduced (temporarily) with insulin and dextrose or epinephrine, but total potassium load is not influenced}

        •  If potassium levels are expected to be labile, serial potassium measurements are required

          • Electrocardiographic changes associated with hyperkalemia (tall, peaked T waves)  may not provide adequate warning of impending heart block secondary to hyperkalemic conditions

• Hypertension--secondary physiological changes

  • Abnormal cerebral and coronary autoregulation-- consequence:

    •  Higher blood-pressure required for adequate perfusion

  • Left ventricular hypertrophy (reduced ventricular compliance, requiring increased dependency on atrial contraction for ventricular filling)-- consequences:

    •  Abnormally atrial rhythms may be associated with significant effects on BP (decreases)

    •  Also, by analogy into blood-pressure is normal during a junctional rhythm, the blood-pressure might increase (hypertensive) upon resumption of normal sinus rhythm

  •  General rule: patients preoperatively hypertensive are likely to be postoperatively hypertensive-- Action:

    •  Rapidly acting vasodilator, e.g. nitroprusside sodium (Nipride) might be useful/required for post- operative hypertension management.

• Primary Reference:  Ross, AF, Gomez, MN. and Tinker, JH Anesthesia for Adult Cardiac Procedures in  Principles and Practice of Anesthesiology (Longnecker, D.E., Tinker, J.H. Morgan, Jr., G. E., eds)  Mosby, St. Louis, Mo., pp. 1659-1698, 1998.

• Primary Reference: Shanewise, JS and Hug, Jr., CC, Anesthesia for Adult Cardiac Surgery, in Anesthesia, 5th edition,vol 2, (Miller, R.D, editor; consulting editors, Cucchiara, RF, Miller, Jr.,ED, Reves, JG, Roizen, MF and Savarese, JJ) Churchill Livingston, a Division of Harcourt Brace and Company, Philadelphia, pp. 1753-1799, 2000.

• Primary Reference: Wray Roth, DL, Rothstein, P and Thomas, SJ Anesthesia for Cardiac Surgery, in Clinical Anesthesia, third edition  (Barash, PG, Cullen, BF, Stoelting, R.K, eds), Lippincott-Raven Publishers, Philadelphia, pp. 835-865, 1997