CARDIOVASCULAR DISORDERS

Cardiac risk assessment for the adult surgical patient is significantly linked to a positive history for cardiac disease and the relative risk for myocardial infarction. The two strongest determinants in this category are a history of coronary artery disease and left ventricular dysfunction with preexisting congestive heart failure (CHF). In assessing these patients, the easiest and most useful index for perioperative risk stratification is the Goldman cardiac risk index. This index has been reported to be less predictable for those with an intermediate risk, but does well in stratifying the high- and low-risk categories for today’s surgical population ( Table 18-1 ).

The Goldman index was revised to include high-risk surgeries, history of ischemic heart disease, history of heart failure, history of cerebral vascular disease, exogenous insulin therapy, and serum creatinine >2 mg/dL. Additions and modifications to the Goldman index include factors such as angina and pulmonary edema by Detsky and medically treated diabetes mellitus by Eagle. From the previously described indexes and research, Grayburn and Hillis have suggested the management strategy for elective surgical candidates as outlined by Joffe and Morgan in Box 18-1 .

Regarding outcomes, Rao and Jacobs evaluated the rate of postoperative reinfarction after general anesthesia for patients with recent myocardial infarctions. Their data suggested a 6% reinfarction rate within 3 months of original infarct, and a 2% reinfarction rate at 3 to 6 months.

CONGENITAL HEART DISORDERS

Congenital heart disease (CHD) is the most common birth defect, approximating 1% of all live births. Structural evaluation, diagnosis, and therapeutic management including antibiotic prophylaxis are required before elective surgery. Common defects in children and young adults include patent ductus arteriosus (PDA), ventricular septal defects (VSDs), and atrial septal defects (ASDs). The degree of morbidity with these congenital defects is determined by the defect size and shunting characteristics. Larger defects with right-to-left shunting create a cyanotic disposition, versus smaller left-to-right defects.

With PDA the embryonic ductus arteriosus fails to close normally and persists as a left-to-right shunt connecting the left pulmonary artery and aorta. There are no symptoms unless left ventricular failure or pulmonary hypertension develops. On examination patients can demonstrate an increased apical impulse, a “machinery” murmur at the time of S2, and thrills. The electrocardiogram (ECG) may be normal or indicative of left ventricular hypertrophy. A chest x-ray film may be normal, with prominent pulmonary artery, aorta, and left atrium. Echocardiography, magnetic resonance imaging (MRI), radionuclide flow studies, and cardiac catheterization can quantify the magnitude of the shunt. Uncorrected PDA in elective surgical patient must demonstrate minimal shunting and symptoms if surgery is to proceed. Antibiotic prophylaxis is required to decrease the risk of endocarditis or endarteritis. The successfully corrected PDA patient requires no special considerations.

The more common VSD involves shunting blood from the left ventricle to the right. As with PDA, the size of the defect and magnitude of the shunt dictate morbidity. Examination reveals a pansystolic murmur maximal at the left sternal border, and thrills are common. An ECG may be normal or may indicate right and/or left ventricular hypertrophy. Chest x-ray films may be normal or may show accentuated pulmonary vasculature. Diagnostic studies are identical to those listed earlier for PDA, with Doppler echocardiography being best. Antibiotic prophylaxis is required if the VSD is patent, but surgeons must remember that up to 40% of VSDs close spontaneously in childhood, and therefore no special considerations would be needed.

In 2007 the American Heart Association revised their recommendations regarding prophylactic antibiotics for the prevention of infective endocarditis. Antibiotics are recommended for the following conditions only:

• •

  Prosthetic cardiac valve

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  Previous infective endocarditis

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  CHD

  • •

    Unrepaired cyanotic CHD, including palliative shunts and conduits

  • •

    Completely repaired CHD with prosthetic material or device via surgery or catheter intervention during the first 6 months after the procedure

  • •

    Repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or device

• •

  Cardiac transplantation recipients who develop cardiac valvulopathy ( Table 18-2 )

  TABLE 18-2

  Prophylactic Antibiotic Regimen

  		Regimen—Single Dose 30-60 Minutes before Procedure
  Situation	Agent	Adults	Children
  Enteral	Amoxicillin	2 g	50 mg/kg
  Parenteral	Ampicillin	2 g IM or IV	50 mg/kg IM or IV
  	or	1 g IM or IV	50 mg/kg IM or IV
  	Cefazolin or ceftriaxone
  Enteral: allergic to penicillin	Cephalexin	2 g	50 mg/kg
  	or	600 mg	20 mg/kg
  	Clindamycin	500 mg	15 mg/kg
  	or
  	Azithromycin or
  	clarithromycin
  Parenteral: allergic to PCN	Cefazolin or ceftriaxone	1 g IM or IV	50 mg/kg IM or IV
  	or	600 mg IM or IV	20 mg/kg IM or IV
  	Clindamycin

  Prevention of Infective Endocarditis—Guidelines from the American Heart Association . Available at: www.ada.org/prof/resources/topics/infective_endocarditis_guidelines.pdf . Accessed October, 2007.

PULMONARY DISORDERS

Pulmonary disorders are classically defined as obstructive, restrictive, or a combination of both. For the adult population, chronic obstructive pulmonary disease is subcategorized into emphysema, chronic bronchitis, and asthma. Restrictive processes include pulmonary fibrosis, scleroderma, obesity, and so on. In any case, a pulmonary risk index should be employed to understand and idealize the surgical candidate. Epstein and co-workers developed five indexes to assess preoperative pulmonary risk. These include obesity, smoking, pulmonary signs, pulmonary function test results, and arterial carbon dioxide level. An increased risk for postoperative pulmonary complications was noted with an increased number of preoperative risk factors ( Box 18-2 ).

Pulmonary disease is the most common chronic illness in children and young adults and accounts for 10% of all nonviolent deaths within these age groups. Two conditions for consideration in the younger orthognathic surgery population are asthma and cystic fibrosis. Both are classified as obstructive pulmonary disorders but can be restrictive with fibrosis from chronic inflammation and infection. Regarding asthma, assessment of the patient’s historical morbidity is crucial in delineating perioperative status. A guide to asthma severity depends on the presenting symptoms with daily activities, nocturnal awakenings, lung function, and medication use as illustrated in Table 18-3 .

Well-controlled asthmatics have no additional risk for developing perioperative pulmonary complications. Continuation of inhalation therapy is advised up to and on the day of surgery. For those patients with persistent exacerbations, their history of induction (e.g., exercise, environmental allergens, upper respiratory infections [URIs], gastroesophageal reflux disease [GERD]) should be weighed, and consideration for a pulmonary function test is warranted. Anesthetic techniques involving the use of ketamine and sevoflurane are beneficial owing to their dilatory effects on the bronchial tree. Sevoflurane is also less irritating and pungent to the upper airway. Glucocorticoids should be considered for latent antiinflammatory benefits, particularly in the moderate to severe asthmatic. In addition, glucocorticoids in conjunction with beta ₂ -agonists have shown synergistic effects in the acute phase as well. Of note, inhaled formulations of glucocorticoids have shown little clinical significance regarding systemic effects (e.g., adrenal crisis). Finally, avoidance of aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) is recommended in asthmatic patients to prevent shifting of the arachidonic acid cascade to accentuate the formation of bronchoconstricting leukotrienes.

Cystic fibrosis is an autosomal recessive disorder that results in an alteration in chloride transport and water flux across the apical surface of epithelial cells. This effect is pervasive in that exocrine glands throughout the body are obstructed by abnormal mucus. Affected patients have impaired mucociliary function, chronic pancreatic insufficiency, and pancreatitis, which may result in diabetes, biliary cirrhosis, and gallstones. Chronic gastrointestinal disturbances have shown an increased risk for malignancy. Male patients are generally infertile. Affected patients experience recurrent bronchitis and bronchiectasis in concurrence with Pseudomonas aeruginosa and Staphylococcus aureus infections. Two consecutive “sweat test” results of chloride >60 mEq/L in children and >80 mEq/L in adults are diagnostic. Elective surgery such as orthognathics in which the airway will be compromised necessitates preoperative intravenous (IV) antibiotics, chest physiotherapy, and bronchodilatory inhalers. Although tremendously expensive, recombinant human deoxyribonuclease reduces sputum viscosity. Additional considerations for surgery include high prevalence of nasal polyps (nasal intubations) and psychosocial ramifications of chronic isolation.

Smoking is typically associated with an older cohort but is certainly applicable to many young adults today. The risk for postoperative cardiopulmonary complications decreases after 8 weeks of smoking cessation. Patients who stop smoking 24 hours before surgery will diminish the adverse effects of nicotine as well as systemic carbon monoxide levels. Patients who abstain from smoking for more than 6 months have a complication rate similar to that in patients who never smoked. The success rate of smoking cessation attempts is one in five with appropriate therapy. Postoperative breathing exercises including incentive spirometry for 15 min four times per day (qid) and hourly coughing reduce the risk of pulmonary complications and are a better postoperative regimen than continuous positive airway pressure.

HEMATOLOGIC DISORDERS

Von Willebrand factor is a protein involved in primary hemostasis via two mechanisms: the activation and adherence of platelets to injured vessel walls to form a primary plug, and stabilization of factor VIII in plasma. Von Willebrand’s disease is the most common inherited bleeding disorder, affecting up to 1% of the population. Clinically these patients have ease of bruising, prolonged bleeding from mucosal surfaces, hemarthrosis, gastrointestinal bleeding, and heavy menstrual bleeding. Diagnosis is made by laboratory screening of plasma von Willebrand factor antigen and activity, factor VIII activity, aPTT, platelet function testing, and bleeding time. Prolonged bleeding times, impaired adhesion of platelets with failure to aggregate with ristocetin, and decreased factor VIII activity confirm von Willebrand’s disease. Von Willebrand’s disease can be classified into three main types:

• •

  Type 1—Partial quantitative deficiency with low vW factor antigen and activity

• •

  Type 2—Qualitative deficiency with discordance in ristocetin cofactor activity and vW factor antigen levels

• •

  Type 3—Severe quantitative deficiency with extremely low vW factor antigen and factor VIII activity only 1-10% of normal

Depending on severity, surgery may result in life-threatening perioperative bleeding. Treatment depends on the clinical condition of the patient and the type of von Willebrand’s disease involved. The goal of therapy is to correct the defect in platelet adhesiveness and factor VIII level. Treatment options include cryoprecipitate, factor VIII concentrates, or desmopressin (DDAVP).

Patients with mild type 1 von Willebrand’s disease (normal bleeding time) are best treated with desmopressin acetate (DDAVP), 3 ug/kg IV diluted in 50 mL normal saline and given over 15 to 30 min. Von Willebrand factor and factor VIII levels increase threefold to sixfold in 90 to 120 min and maintain this level for 4 to 8 hours. DDAVP is not effective for type III disease and some variants of type II (type IIb) owing to thrombocytopenia.

Patients with moderate to severe von Willebrand’s disease requiring elective orthognathic surgery necessitate transfusion with cryoprecipitate. Each unit of cryoprecipitate raises the factor level by 3%, with a target level of 50% before surgery. ɛ-Aminocaproic acid given 12 to 24 hours before surgery and continued for 12 days postoperatively is also recommended.

Sickle cell trait and disease primarily affect individuals from Central African ancestry. Approximately 0.2-0.5% of African-Americans are homozygous (disease) for the sickle gene, and 8-10% are heterozygous (trait). Sickling of the red blood cells results in a loss in oxygen-carrying capacity, coalescing, increased viscosity, and reduced blood flow, exacerbating hypoxia and vascular occlusion. Individuals with sickle cell trait are less symptomatic.

Sickle cell crisis is a collection of clinical signs and symptoms presenting as anemia, joint pain, jaundice, pallor, organomegaly, renal and spleen dysfunction, cardiac failure, and stroke. In jaw surgery an increased incidence of osteomyelitis and osteonecrosis may be expected owing to infection of infarcted bone.

The goal of perioperative management is prevention of crisis. Hydration, normothermia, pain management, and optimized oxygen carrying capacity are essential. Folic acid deficiency may play a role in the cause of the sickle cell crisis; therefore folic acid dietary supplements are recommended. Antibiotic prophylaxis for surgical procedures is also recommended. Preoperative partial transfusion therapy may be considered to increase hemoglobin concentration to 10 mg/dL. Intraoperative considerations should include avoidance of hypothermia and hyperthermia, acidosis, hypoxemia, hypotension, and hypovolemia. Decreased oxygen may result in pulmonary complications and decreased wound healing.

Hemophilia A is caused by a serum deficiency of factor VIII, and it occurs in 85% of hemophiliacs. Hemophilia B is due to a deficiency of factor IX and occurs in 15% of hemophiliacs. Patients with hemophilia have normal primary hemostasis but delayed bleeding after trauma or surgery. Patients with severe disease will exhibit multiple episodes of spontaneous bleeding into joints, bones, and muscles. Diagnosis of hemophilia includes family history, spontaneous hemarthrosis, bleeding into deep tissues, and hematuria. Laboratory tests demonstrate prolonged aPTT while prothrombin time (PT) and bleeding time remain normal. Symptomatic patients who bruise easily and have factor VIII >5% are considered mild hemophiliacs. Individuals with factor VIII between 1% and 5% who have prolonged bleeding after injury or surgery are considered moderate hemophiliacs. Severe forms occur when the factor VIII level is less than 1% of normal. These individuals demonstrate spontaneous epistaxis, hemarthrosis, and gingival and uterine bleeding.

Normal hemostasis requires at least 25% factor VIII activity. Increasing factor VIII to more than 50% is recommended before surgery. This can be achieved with factor VIII concentrate, cryoprecipitate, or fresh frozen plasma. Intraoperatively, management of hemophiliacs depends on the degree of severity.

• •

  Mild cases exhibit >5% factor VIII and can be treated with DDAVP 0.3 mcg/kg IV 2 hours preoperatively to raise factor VIII to 25%.

• •

  Moderate cases exhibit 1-5% factor VIII and may require cryoprecipitate or factor VIII concentration to raise factor VIII to 50%. Repeat infusion as necessary to maintain level >25% for 2 to 3 days.

• •

  Severe cases have <1% factor VIII and will require preoperative factor VIII of 100% maintained for several days. ɛ-Aminocaproic acid 100 mg/kg should be given 4 hours before surgery, then every 6 hours, and maintained for 7 days postoperatively.

ENDOCRINE DISORDERS

Diabetes mellitus type I is due to autoimmune destruction of beta cells of the pancreatic islet. The insulin-dependent diabetes mellitus (IDDM) patient is predisposed to hyperglycemic states, ketoacidosis, and severe metabolic abnormalities. To counter the previously mentioned complications, the IDDM patient requires exogenous insulin regimens generally dosed at 0.5 to 1 U/kg/day. Standard therapy consists of twice daily (bid) subcutaneous injections of intermediate (NPH) or long-acting insulin, with short-acting or rapid-acting insulin as needed for ideal control. In addition, affected patients who undergo elective orthognathic surgery are at significant risk for sepsis, hypotension, hypovolemia, and acidosis. Preoperative work-up should include consultation with the patient’s physician regarding current level of control and evaluation for renal function, heart disease, neuropathy, gastroparesis, and history of diabetic ketoacidosis (DKA). Preoperative ECG should identify ischemic changes, and chemistries including blood urea nitrogen (BUN) and creatinine and urinalysis for microalbuminuria and proteinuria should alert the physician regarding electrolyte imbalances and renal disease, respectively. Glucose levels can be assessed via glucometry or chemistry analysis for short-term control, and glycosylated hemoglobin (A1c) for long-term control. Forty-eight hours before surgery, IDDM patients should be switched to intermediate-acting insulin and short-acting insulin for tighter control. On the day of surgery, the patient’s morning dose of intermediate-acting insulin is held to 50% of the usual dose and the short-acting insulin is completely withheld. Given nothing by mouth (NPO) status, surgery should be scheduled as the first morning case. A glucose level should be obtained in the preoperative holding area, and IV insulin and glucose should be administered 1 hour before surgery. Conventionally a sliding scale regimen was used, but this has come under significant skepticism as to efficacy. A continuous IV infusion of regular insulin is recommended with supplemental glucose at 5 to 10 g/hour and potassium at 2 to 4 mEq/h. Postoperative management should include continuation of the intraoperative regimen with hourly glucose levels and daily potassium levels. Discharge criteria dictate that this cohort of patients should be hospitalized until they can consume their first solid diet (soft nonchew). For the orthognathic patient, this can be a challenge. At such time, subcutaneous insulin can be reinstituted and the IV infusion withheld, assuming acceptable glucose and potassium levels. In addition, postoperative urinalysis illustrating glucose, ketone, and protein levels is an inexpensive way of assessing the patient’s state of protein catabolism. Postoperative antibiotics, hydration, nutrition, and home insulin regimen are crucial for wound healing and recovery. Perioperative glucocorticoids are controversial for this patient population owing to the metabolic balancing act between insulin and counterregulatory hormones. We prefer not to use steroids in such cases.

Adrenocortical insufficiency is a rare disorder resulting from endogenous deficiency (primary) or exogenous suppression (secondary). Although case reports exist attesting hypotensive complications with correction via glucocorticoids, it is not known whether perioperative administration of high-dose glucocorticoids decreases the risk of these complications. In a double-blinded study, Glowniak and Loriaux found no differences in perioperative complications between high-dose glucocorticoid therapy versus simply administering chronic glucocorticoid medications in patients with secondary adrenal suppression. Nonetheless, adrenal suppression should be suspected in those patients receiving the equivalent of 20 mg of prednisone daily for 1 week or the equivalent of 7.5 mg of prednisone daily for 1 month within the past year. A conventional regimen is 100 mg IV hydrocortisone at induction of anesthesia, followed by 100 mg every 8 hours for 48 to 72 hours. At this amount, tapering is controversial, but dividing the dose in half each day for 4 to 6 days with equivalent oral (PO) steroids is an option.

Overweight and obesity can be measured by calculating the body mass index (BMI). BMI is equal to weight in kilograms divided by height in meters . Overweight is equated to a BMI of 25 to 29.9 kg/m ² , and obesity is BMI ≥30 kg/m ² . From a pulmonary perspective, the obese patient is known to have reduced functional residual capacity, vital capacity, and total lung capacity. In turn, general anesthetic agents and the effects of surgery increase postoperative apnea, atelectasis, and hypoxemia. Preoperative Mallampati scores should be assessed but may be less predictable in the obese patient. In addition, cervical range of motion and maximum incisal opening should be noted. Patient positioning is also crucial. Reverse Trendelenburg and semi-Fowler positions are favored over supine for ideal ventilation, and pressure points should be minimized. Oxygen is critical before, during, and after surgery in concert with incentive spirometry. Obese patients have a high acidic gastric content and higher gastric volumes; therefore risk for gastric reflux and aspiration can be reduced with the administration of preoperative medications such as Bicitra (Baker Norton Pharmaceuticals, Miami, Florida), metoclopramide, and H ₂