Blueprints Surgery, 5th Edition

Part I - Introduction

Chapter 2

Care of the Surgical Patient

PREOPERATIVE EVALUATION

Preoperative evaluation has two main purposes: identification of modifiable risk factors and risk assessment. Unless the situation is emergent, every patient should have a detailed history and physical examination. In all patients, attention should be given to a history of cerebrovascular accident, heart disease of any kind, pulmonary disease, renal disease, liver disease and other gastrointestinal disorders, diabetes, prior surgeries, bleeding problems, clotting problems, difficulty with anesthesia, poor nutrition, alcohol use, and illicit drug use. Allergies, current medications, family history, social history, and a careful and complete review of systems should be conducted. Often, the review of systems will reveal problems that require more detailed workup.

Physical examination should be focused on identifying problems that require further workup. For example, facial asymmetry, speech problems, weakness, or a carotid bruit may suggest prior cerebrovascular incident that requires further workup. Cardiac disease may present with evidence of congestive heart failure, crackles on lung examination, or jugular venous distention.

Pulmonary disease may result in, for example, a barrel chest with poor air movement in patients with chronic obstructive pulmonary disease or wheezing in patients with asthma. Liver disease may cause ascites, caput medusae, telangiectasias, or asterixis. Ecchymosis may be evidence of bleeding problems, whereas extremity swelling may result from clotting disorders.

Choice of laboratory studies depends on the patient's underlying medical condition and the extent of the surgery. There has been a trend toward less routine testing and increased reliance on the history and physical examination. In otherwise healthy patients undergoing minor surgery, laboratory studies, including coagulation studies, are probably not indicated. Similarly, in patients with no history of pulmonary or cardiac disease and no significant risk factors undergoing minor or moderate surgery, electrocardiogram (ECG) and chest x-ray (CXR) are also probably not indicated.

General guidelines for preoperative testing in patients without risk factors are as follows:

  • ECG: Male older than 40 years or female older than 50 years undergoing cardiovascular procedures
  • CXR: All patients older than 60 years or undergoing thoracic procedures
  • Hematocrit: All patients if the procedure is expected to cause >500 mL of blood loss
  • Creatinine: Patients older than 50 years or if the procedure has a high risk for generating renal failure
  • Pregnancy test: All women of childbearing age if pregnancy status is uncertain

MODIFICATION OF RISK FACTORS IN THE PREOPERATIVE PERIOD

Initial preoperative evaluation may suggest additional testing needed, either to determine the surgical risk or to further identify modifiable factors. For example, chest pain or shortness of breath with mild exertion should prompt a more thorough cardiac evaluation, including an ECG and stress test. If these tests show cardiac disease, a decision will need to be made regarding whether the patient requires an intervention before surgery. If preoperative

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assessment demonstrates carotid artery disease, it may be best to perform an endarterectomy before the originally planned surgery. Other issues, such as poorly controlled diabetes, obesity, and malnutrition, should also be addressed before surgery. This may involve modifications of diet and insulin dose, weight loss, or inpatient admission for total parenteral nutrition. Good glucose control in diabetics as measured by hemoglobin A1c levels is associated with improved outcomes after surgery. In patients suffering from malnutrition scheduled for surgery, preoperative total parenteral nutrition has been shown to improve outcomes.

TIMING OF SURGERY

Once the risk factors for surgery have been identified, a frank discussion should be held with the patient explaining the potential risks and benefits of the surgery and which risk factors should be addressed before the surgery. This discussion should be the basis for the informed consent for surgery. The outcome of this discussion may be that the surgery should proceed without delay, that the procedure is too risky and should not be attempted, or somewhere in between. For example, in a young healthy person with a symptomatic inguinal hernia, surgery without delay is indicated. On the other hand, if the hernia is small and asymptomatic and the patient has advanced liver disease with uncontrolled ascites, the risk of the surgery probably outweighs the benefits. In a patient with end-stage renal disease undergoing workup for a kidney transplant who is found to have unstable angina and coronary disease amenable to intervention, the coronary intervention should proceed before transplantation. When operation occurs within 3 months of a myocar-dial infarction, the risk of a subsequent one is approximately 30% in the perioperative period and decreases to less than 5% after 6 months, so that surgery should be delayed in these patients if at all possible. The Goldman criteria, although offered in 1977, are still widely used to evaluate surgical risk (Table 2-1). More recent criteria from the American College of Cardiology and the American Heart Association provide algorithms for assessing risk. Outcomes, especially for class IV risk patients, are much better with improvements in medical and surgical care, but the classification is a useful one to help stratify surgical risk.

TABLE 2-1 Goldman Criteria for Cardiac Risk

Factor

Point
Value

Age >70 years

5

Myocardial infarction within 6 months

10

S3 gallop or JVP >12 cm

11

Significant valvular stenosis

3

Rhythm other than sinus, or atrial ectopy

7

Ventricular premature beats >5/min at
any time

7

PO2 <60 or PCO2 >50 mm Hg, or
Potassium <3 mEq/L or HCO3 <20, or
BUN >50 mg/dL or creatinine
>3.0 mg/dL, or chronic liver disease
or debilitation

3

Intraperitoneal, intrathoracic, or aortic
surgery

3

Emergency surgery

4

Risk assessed as follows: 0–5 points, class I, 1% complication risk;
6–12 points, class II, 7% complication risk; 13–25 points, class III,
14% complication risk; >25 points, class IV, 78% complication risk.

JVP, jugular venous pressure; PO2, partial pressure of oxygen; PCO2,
partial pressure of carbon dioxide; HCO3, bicarbonate; BUN, blood
urea nitrogen.

DIABETES MANAGEMENT BEFORE SURGERY

There are a number of ways to manage glucose levels before and during surgery in patients with diabetes. If possible, patients with diabetes should be scheduled as the first case of the day to simplify glucose control, as patients will not be eating. For day surgery, in patients with type I diabetes or those with type II diabetes requiring multiple injections, patients should take one half of their usual dose of intermediate-acting or long-acting insulin the morning of surgery. When these patients undergo major surgery, they can hold their insulin entirely in preparation for intravenous therapy during the operation.

For patients with type II diabetes taking once-daily or twice-daily insulin, or for patients on oral medications undergoing day surgery, oral hypoglycemics should be held, and one half dose of intermediate-acting insulin should be given in the morning. Patients undergoing major surgery can be managed intraoperatively with intravenous insulin. Glucose levels should

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be checked on arrival for surgery and every 2 hours while waiting.

PERIOPERATIVE MANAGEMENT

FLUIDS AND ELECTROLYTES

Fluids and electrolytes must be provided in adequate amounts to replace intraoperative losses. This will maintain blood pressure and ensure optimal cardiac function. Choice of fluids depends on the underlying medical problems. For example, the use of potassium-containing fluids should be avoided in patients with renal failure. For longer and more complicated cases, consideration of loss of other electrolytes, including calcium and magnesium, must be addressed.

BLOOD PRODUCTS

Administration of blood products depends on the underlying health of the patient and the type of operation. Whereas in a healthy patient with a limited intraoperative event in which 500 mL of blood is lost, resulting in a hematocrit of 24%, a transfusion may not be indicated. However, for a patient undergoing liver transplantation with expected ongoing blood loss, transfusion may be indicated at a level of 28%. Transfusion of fresh-frozen plasma and platelets should be considered for patients with coagulopathy or thrombocytopenia.

CARDIAC RISK FACTORS

In patients with known cardiac disease, aggressive intraoperative lowering of myocardial oxygen demand with beta-blockers has been shown in randomized trials to improve outcomes and should be used.

ANTIBIOTICS

Antibiotics are of benefit in all procedures in which a body cavity is opened and are probably useful in clean procedures. Guidelines for the use of antibiotics include administration before the incision (within 1 hour) and redosing after 4 hours. Specific recommendations are shown in Table 2-2.

TABLE 2-2 Antibiotic Recommendations

Type of Procedure

Antibiotic Choice

Clean

Cefazolin or none

Cardiovascular

Cefazolin

Colorectal

Oral: Neomycin/erythromycin
base plus mechanical
cleansing before surgery
Parenteral: cefazolin/
metronidazole or cefotetan

Prosthetic joint

Cefazolin

DIABETES MANAGEMENT

A large randomized controlled trial published in 2001 by Van den Berge et al demonstrated improved outcomes in surgical intensive care patients maintained with strict blood sugar control between 80 and 110 mg/dL. Since then, there has been tremendous activity in defining which patients benefit from this therapy and evaluating the complications. Many patients, including those undergoing general or cardiac surgery, benefit from improved outcomes and decreased infectious complications, including reduced septicemia. Patients using these regimens must be monitored carefully to prevent the development of hypoglycemia.

PREVENTION OF DEEP VENOUS THROMBOSIS

Prevention of deep venous thrombosis is of major importance. Although rare, this complication is potentially life-threatening. Randomized clinical trials are abundantly clear. When heparin is given, it should be done so in the preoperative area, before the incision. Administration of any anticoagulation in the perioperative period must carefully consider the risk of bleeding, and therapy should be individualized to the patient and the particulars of the operation (e.g., if the operation was unusually bloody). Having stated that, there is evidence that the following regimens are efficacious in improving outcomes.

Minor Surgery

In patients younger than 40 years undergoing minor surgery with no risk factors, early ambulation decreases risk of deep venous thrombosis, and use of subcutaneous heparin is controversial. In patients between 40 and 60 years or with risk factors, heparin 5000 U administered subcutaneously 2 times per day or enoxaparin 40 mg administered subcutaneously every day is beneficial. In patients older than 60 years or with

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additional risk factors, heparin can be increased to 3 times per day, or enoxaparin 30 mg administered subcutaneously 2 times per day is beneficial.

Major Surgery

Patients younger than 40 years with no risk factors should receive heparin 5000 U subcutaneously 2 times per day or enoxaparin 40 mg subcutaneously every day. Patients older than 40 years or with risk factors should receive heparin 5000 U subcutaneously 3 times per day or enoxaparin 30 mg subcutaneously 2 times per day.

Orthopedic Surgery

Because of the increased risk of these procedures, aggressive anticoagulation is indicated. Patients undergoing hip fracture repair, total hip replacement, or total knee replacement should receive enoxaparin 30 mg subcutaneously 2 times per day, coumadin to keep international normalized ratio between 2 and 3, or fondaparinux 2.5 mg.

Graded compression stockings and intermittent pneumatic compression boots are often used in combination with pharmacologic therapy, but their benefit is less well established.

TEMPERATURE

Maintenance of normal intraoperative temperature is critical for adequate hemostasis and optimal cardiovascular function. Use of warmed fluids and warming blankets may be necessary for long operations or those in which large body cavities are opened.

POSTOPERATIVE MANAGEMENT

Principles of postoperative management include early mobilization, pulmonary therapy, early nutrition, adequate fluid and electrolyte administration, management of cardiac risk factors, control of blood sugars, and recognition of complications.

Early mobilization is important to prevent muscle wasting and weakness, reduce the risk of venous thromboembolism, reduce the rate of pneumonia, and perhaps speed the return of bowel function. If permitted by the type of surgery, the patient should get out of bed on the day of surgery and be walking on the first postoperative day.

One of the most common postoperative complications is pneumonia. Deep-breathing exercises and the use of an incentive spirometer can decrease this risk.

Early nutrition (within 24 hours of surgery) has been demonstrated in randomized controlled trials to improve outcomes. In most patients, this will amount to having them eat, but many patients may require a nasoenteric tube for this purpose. In patients undergoing surgery on the gastrointestinal tract, the timing of feeds should be individualized to the patient and the type of operation. In general, enteral nutrition is preferable to parenteral nutrition if the gut is functional.

Fluid administration is one of the most important aspects of postoperative care. Adequate resuscitation prevents renal failure and optimizes cardiac function. Excessive fluid can cause congestive heart failure and edema, which in turn inhibits wound healing. Fluid administration must be individualized to the patient and the type of operation; general guidelines are to administer fluid to keep the urine output >30 mL/hr.

Decreasing cardiac risk in patients with preexisting disease requires adequate beta blockade throughout the perioperative period. The heart rate should be kept <70 and lower if hemodynamically tolerated.

Tight control of blood sugars is clearly beneficial in reducing wound infections. This is accomplished initially by aggressive use of sliding-scale insulin and resumption of the patient's home insulin regimen when the patient is eating adequately.

Early recognition of surgical complications is critical to effectively managing them. Common to all but the most minor operations are wound infections, pneumonia, urinary tract infection, catheter infections, deep venous thrombosis, and myocardial infarction. In addition, each operation has its specific complications. Recognition of a complication depends on detailed daily history and physical examination. Wounds should be examined for erythema and discharge. Particularly worrisome is murky brown discharge that may represent a dehiscence or necrotizing fasciitis. Lungs should be examined daily for decreased breath sounds and egophony, and sputum should be examined. Thick green or brown sputum should prompt investigation for pneumonia, including CXR and sputum gram stain and culture. Sites of catheter placement should be examined for erythema and discharge. Urinary symptoms should prompt a urinalysis and culture. Chest pain in the perioperative period should be taken seriously and evaluated with an ECG and cardiac enzymes in the appropriate clinical setting.

Fever is an exceedingly common occurrence in the perioperative period, and early diagnosis is critical. The

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classic "5 Ws" of wind (pneumonia), wound, walking (deep venous thrombosis), water (urinary tract infection), and wonder drugs (drug reaction) should be considered in all patients. Fevers on the first day after surgery are generally attributed to the inflammatory stress of the surgery or atelectasis. If the fever is not high and history and physical examination are unremarkable, no further workup is indicated. If, on the other hand, the fever is high, the wound should be examined to rule out a rapidly progressive infection, typically caused by Gram-positive cocci. Other diagnostic modalities should be used based on the type of surgery and symptoms. An increasingly common source of fever is Clostridium difficile colitis. This should be suspected in any patient with diarrhea after surgery. Three stool samples and a white blood cell count should be sent. Initiation of treatment before laboratory confirmation may be indicated if the suspicion is high.

Examples of complications related to the surgery include fascial dehiscence, breakdown or stricture of enteric anastomoses, thrombosis of vascular grafts, deep space infections, and hernia recurrence. These problems can usually be recognized with careful patient examination.

FLUIDS AND ELECTROLYTES

Understanding fluid and electrolyte replacement begins with knowing the composition of the various body compartments. In a typical 70-kg person, 60% of total body weight is water. Two thirds of this water is contained in the intracellular compartment, and one third is in the extracellular compartment. One quarter of this extracellular water is plasma—approximately 3.5 L in a typical man. Red blood cell volume is approximately 1.5 L. Combined with plasma, this results in a blood volume of approximately 5 L. Electrolyte concentrations in the extracellular and intracellular space are as shown in Table 2-3.

TABLE 2-3 Electrolyte Concentrations in the Extracellular and Intracellular Space

Electrolyte

Extracellular
(mEq/L)

Intracellular
(mEq/L)

Sodium

140

10

Potassium

4.0

150

Calcium

2.5

4.0

Magnesium

1.1

34

Chloride

104

4.0

Carbonate

24

12

Phosphate

2.0

40

Daily maintenance requirements for healthy adults include urinary fluid loss of 1 L, gastrointestinal loss of 200 mL, and insensible losses of 10 mL/kg. Each of these numbers can be adjusted upward in various disease states. Fever, burns, and diarrhea are examples of processes that can dramatically increase fluid losses.

Normal replacement in surgical patients is 1 mEq/kg of sodium and 0.5 mEq/kg of potassium per day. Gastrointestinal losses in patients can be approximated with the information provided in Table 2-4. The composition of various replacement fluids is as shown in Table 2-5.

TABLE 2-4 Normal Replacement of Fluids in Surgical Patients (mEq/L)

Type of Fluid

Sodium

Potassium

H+

Bicarbonate

Gastric

20–120

12

30–100

0

Duodenal

110

15

0

10

Ileum (ileostomy)

100

10

0

40

Colon (diarrhea)

120

25

0

45

Bile

140

5

0

25

Pancreas

140

5

0

115

TABLE 2-5 Composition of Various Replacement Fluids (mEq/L)

Replacement Fluid

Sodium

Potassium

Chloride

Calcium

Lactate

Normal saline

154

154

0

0

0

Half normal saline

77

77

0

0

0

Lactated Ringer's Solution

130

4

109

3

28

Common electrolyte abnormalities in the perioperative period include hyponatremia, hypernatremia, hyperkalemia, and hypokalemia. Causes of hyponatremia should be divided into two types, depending on whether there is reduced plasma osmolality. If plasma osmolality is normal or high, the differential diagnosis is hyperlipidemia, hyperproteinemia, hyperglycemia, and mannitol administration. In this case, the treatment focuses on correcting the abnormality in the osmotically active agent.

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More often, the plasma osmolality is reduced. In this case, the question becomes whether the circulating plasma volume is high, as in congestive heart failure, cirrhosis, nephrotic syndrome, and malnutrition; normal, as in syndrome of inappropriate secretion of antidiuretic hormone, paraneoplastic syndromes, endocrine disorders, and various drugs (morphine, aminophylline, indomethacin); or low, with excessive losses or inadequate replacement.

In general, patients with decreased plasma volume should be treated with hypertonic saline if the level is low enough to warrant treatment (<120 mEq/L). In this case, it is critically important to not correct the sodium >0.5 mEq/L per hour. If the patient's are symptomatic, however, it may be advisable to increase the level more quickly. This should only be done in consultation with a neurologist, as faster rates can result in central pontine myelinolysis from the osmotic shift. Patients in whom the effective plasma volume is high should be treated with fluid restriction.

Causes of hypernatremia are divided into water loss and sodium administration. Water loss can result from insensible losses from infection, burns, or fever; renal loss from diabetes insipidus; gastrointestinal losses; or hypothalamic disorders. Sodium administration can be performed via ingestion or intravenously. Treatment consists of addressing the underlying abnormality and administering fluid. Correction of hypernatremia should not progress at a rate >0.5 mEq/L per hour, unless neurologic symptoms are present. Rapid correction of hyponatremia can result in seizures, cerebral edema, and death.

Hypokalemia is usually due to potassium loss. Hypokalemia can result in cardiac arrhythmias, especially in patients taking digoxin. Treatment is with exogenous replacement.

Hyperkalemia is usually due to exogenous administration or from intracellular stores. It can result in weakness and cardiac arrhythmias. If the level is above 6 mEq/L or the patient has ECG changes, treatment with calcium gluconate, sodium bicarbonate, insulin, and glucose can transiently decrease plasma potassium, which may rebound, because these treatments do not alter the total body potassium. Kayexalate decreases total body potassium but takes longer to be effective. Dialysis is extremely effective in decreasing potassium.

KEY POINTS

  • Preoperative evaluation is critical to identify modifiable risk factors and provide risk assessment.
  • Cardiac history is essential to the evaluation. Goldman criteria can help assess cardiac risk.
  • Operation within 3 months of a myocardial infarction is associated with a 30% complication risk.
  • Tight glucose control in the perioperative period improves outcomes.
  • Anticoagulation in the perioperative period reduces the risk of deep venous thrombosis.
  • Enteral nutrition is preferable to parenteral nutrition if the gut is functional.
  • Fever in the perioperative period is most commonly caused by the 5 Ws: wind (pneumonia), wound, walking (deep venous thrombosis), water (urinary tract infection), and wonder drugs (drug reaction).


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