Principles of Preoperative and Operative Surgery by mikesanye

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									Principles of Preoperative
 and Operative Surgery
         Sabiston 2007
     Presented in April 2008
      By Dr. S. Noorshafiee
 Preoperative Preparation of the Patient
 Systems Approach to Preoperative
  Evaluation
 Additional Preoperative Considerations
 Preoperative Checklist
PREOPERATIVE PREPARATION
     OF THE PATIENT
   The modern preparation of a patient for
    surgery is epitomized by the
    convergence of the art and science of
    the surgical discipline. The context in
    which preoperative preparation is
    conducted ranges from an outpatient
    office visit to hospital inpatient
    consultation to emergency department
    evaluation of a patient.
   Approaches to preoperative evaluation
    differ significantly, depending on the
    nature of the complaint and the
    proposed surgical intervention, patient
    health and assessment of risk factors,
    and the results of directed
    investigation and interventions to
    optimize the patient's overall status
    and readiness for surgery.
   This chapter reviews the components of
    risk assessment applicable to the
    evaluation of any patient for surgery
    and attempts to provide some basic
    algorithms to aid in the preparation of
    patients for surgery.
      Determining the Need for
              Surgery
   Patients are often referred to surgeons
    with a suspected surgical diagnosis and
    the results of supporting investigations
    in hand. In this context, the surgeon's
    initial encounter with the patient may
    be largely directed toward confirmation
    of relevant physical findings and review
    of the clinical history and laboratory
    and investigative tests that support the
    diagnosis.
   A recommendation regarding the need
    for operative intervention can then be
    made by the surgeon and discussed with
    the patient's family members. A
    decision to perform additional
    investigative tests or consideration of
    alternative therapeutic options may
    postpone the decision for surgical
    intervention from this initial encounter
    to a later time
   It is important for the surgeon to
    explain the context of the illness and
    the benefit of different surgical
    interventions, further investigation, and
    possible nonsurgical alternatives, when
    appropriate
   The surgeon's approach to the patient
    and family during the initial encounter
    should be one that fosters a bond of
    trust and opens a line of communication
    among all participants. A professional
    and unhurried approach is mandatory,
    with time taken to listen to concerns
    and answer questions posed by the
    patient and family members.
   The surgeon's initial encounter with a
    patient should result in the patient
    being able to express a basic
    understanding of the disease process
    and the need for further investigation
    and possible surgical management. A
    well-articulated follow-up plan is
    essential.
Perioperative Decision Making
   Once the decision has been made to
    proceed with operative management, a
    number of considerations must be
    addressed regarding the timing and site
    of surgery, the type of anesthesia, and
    the preoperative preparation necessary
    to understand the patient's risk and
    optimize the outcome.
   These components of risk assessment
    take into account both the
    perioperative (intraoperative period
    through 48 hours postoperatively) and
    the later postoperative (up to 30 days)
    periods and seek to identify factors
    that may contribute to patient
    morbidity during these periods.
      Preoperative Evaluation
   The aim of preoperative evaluation is
    not to screen broadly for undiagnosed
    disease but rather to identify and
    quantify any comorbidity that may have
    an impact on the operative outcome
   This evaluation is driven by findings on
    the history and physical examination
    suggestive of organ system dysfunction
    or by epidemiologic data suggesting the
    benefit of evaluation based on age,
    gender, or patterns of disease
    progression. The goal is to uncover
    problem areas that may require further
    investigation or be amenable to
    preoperative optimization
   Routine preoperative testing is not
    cost-effective and, even in the elderly,
    is less predictive of perioperative
    morbidity than the American Society of
    Anesthesiologists (ASA) status or
    American Heart Association
   The preoperative evaluation is
    determined in light of the planned
    procedure (low, medium, or high risk),
    the planned anesthetic technique, and
    the postoperative disposition of the
    patient (outpatient or inpatient, ward
    bed, or intensive care
   In addition, the preoperative evaluation
    is used to identify patient risk factors
    for postoperative morbidity and
    mortality.
   If preoperative evaluation uncovers
    significant comorbidity or evidence of
    poor control of an underlying disease
    process, consultation with an internist
    or medical subspecialist may be required
    to facilitate the workup and direct
    management. In this process,
    communication between the surgeon and
    consultants is essential to define
    realistic goals for this optimization
    process and to expedite surgical
    management
SYSTEMS APPROACH TO
   PREOPERATIVE
    EVALUATION
             Cardiovascular
   Cardiovascular disease is the leading
    cause of death in the industrialized
    world, and its contribution to
    perioperative mortality during
    noncardiac surgery is significant. Of the
    27 million patients undergoing surgery in
    the United States every year, 8 million,
    or nearly 30%, have significant coronary
    artery disease or other cardiac
    comorbid conditions.
   One million of these patients will
    experience perioperative cardiac
    complications, with substantial
    morbidity, mortality, and cost.
    Consequently, much of the preoperative
    risk assessment and patient preparation
    centers on the cardiovascular system.
One of the first anesthesia risk categorization
  systems was the ASA classification. It has
  five stratifications:
 I—Normal healthy patient
 II—Patient with mild systemic disease
III—Patient with severe systemic disease that
  limits activity but is not incapacitating
IV—Patient who has incapacitating disease that
  is a constant threat to life
 V—Moribund patient not expected to survive
  24 hours with or without an operation
There are more other systems for
 evaluation of cardiovascular risk such
 as:
Goldman cardiac risk index,1977
Detsky modified multifactorial index 1986
Eagle's Criteria for Cardiac Risk
 Assessment, 1989
Revised Cardiac Risk Index
   Once these data have been obtained,
    the surgeon and consultants need to
    weigh the benefits of surgery against
    the risk and determine whether any
    perioperative intervention will reduce
    the probability of a cardiac event
   This intervention usually centers on
    coronary revascularization via coronary
    artery bypass or percutaneous
    transluminal coronary angioplasty but
    may include modification of the choice
    of anesthetic or the use of invasive
    intraoperative monitoring
   Patients who have undergone a
    percutaneous coronary intervention with
    stenting need to have elective
    noncardiac procedures delayed for 4 to
    6 weeks, although the delay may be
    shortened depending on the type of
    stent used (drug eluting versus non–drug
    eluting
   The optimal timing of a surgical
    procedure after myocardial infarction
    (MI) is dependent on the duration of
    time since the event and assessment of
    the patient's risk for ischemia, either
    by clinical symptoms or by noninvasive
    study
Any patient can be evaluated as a surgical
 candidate after an acute MI (within 7
 days of evaluation) or a recent MI
 (within 7-30 days of evaluation). The
 infarction event is considered a major
 clinical predictor in the context of
 ongoing risk for ischemia
   The risk for reinfarction is generally
    considered low in the absence of such
    demonstrated risk. General
    recommendations are to wait 4 to 6
    weeks after MI to perform elective
    surgery
   Improvements in postoperative care
    have centered on decreasing the
    adrenergic surge associated with
    surgery and halting platelet activation
    and microvascular thrombosis
   Perioperative risk for cardiovascular
    morbidity and mortality was decreased
    by 67% and 55%, respectively, in
    ACC/AHA-defined medium- to high-risk
    patients receiving β-blockers in the
    perioperative period versus those
    receiving placebo.
   Although the benefit was most noticeable in
    the 6 months after surgery, event-free
    survival was significantly better in the group
    that received β-blockers up to 2 years after
    surgery.The current AHA/ACC
    recommendations are to start β-blocker
    therapy in medium- to high-risk patients
    undergoing major- to intermediate-risk
    surgery as early as possible preoperatively
    and titrate to a heart rate of 60 beats per
    minute. The choice of agent and duration of
    therapy are still being debated
   An easy, inexpensive method to
    determine cardiopulmonary functional
    status for noncardiac surgery is the
    patient's ability or inability to climb two
    flights of stairs. Two flights of stairs is
    needed because it demands greater
    than 4 metabolic equivalents (METs).
   In a review of all studies of stair
    climbing as preoperative assessment,
    prospective studies have shown it to be
    a good predictor of mortality associated
    with thoracic surgery. In major
    noncardiac surgery, an inability to climb
    two flights of stairs is an independent
    predictor of perioperative morbidity,
    but not mortality.
             Pulmonary
   Preoperative evaluation of pulmonary
    function may be necessary for either
    thoracic or general surgical procedures.
   Whereas extremity, neurologic, and
    lower abdominal surgical procedures
    have little effect on pulmonary function
    and do not routinely require pulmonary
    function studies, thoracic and upper
    abdominal procedures can decrease
    pulmonary function and predispose to
    pulmonary complications
   Accordingly, it is wise to consider
    assessment of pulmonary function for
    all lung resection cases, for thoracic
    procedures requiring single-lung
    ventilation, and for major abdominal and
    thoracic cases in patients who are older
    than 60 years, have significant
    underlying medical disease, smoke, or
    have overt pulmonary symptomatology
   Necessary tests include forced
    expiratory volume in 1 second (FEV1),
    forced vital capacity, and the diffusing
    capacity of carbon monoxide
   Adults with an FEV1 of less than 0.8 L/sec, or
    30% of predicted, have a high risk for
    complications and postoperative pulmonary
    insufficiency. Pulmonary resections need to be
    planned so that the postoperative FEV1 is
    greater than 0.8 L/sec, or 30% of predicted.
    Such planning can be done with the aid of
    quantitative lung scans, which can indicate
    which segments of the lung are functional
   Preoperative pulmonary assessment
    determines not only factors that confer
    increased risk but also potential targets
    to reduce the risk for pulmonary
    complications
   General factors that increase risk for
    postoperative pulmonary complications
    include increasing age, lower albumin
    level, weight loss, and possibly obesity
   Concurrent comorbid conditions such as
    impaired sensorium, previous stroke,
    congestive heart failure, acute renal
    failure, chronic steroid use, and blood
    transfusion are also associated with
    increased risk for postoperative
    pulmonary complications
   Specific pulmonary risk factors include
    chronic obstructive pulmonary disease,
    smoking, preoperative sputum
    production, pneumonia, dyspnea, and
    obstructive sleep apnea.
   Preoperative interventions that may
    decrease postoperative pulmonary
    complications include smoking cessation (>2
    months before the planned procedure),
    bronchodilator therapy, antibiotic therapy
    for preexisting infection, and pretreatment
    of asthmatic patients with steroids.
    Perioperative strategies include the use of
    epidural anesthesia, vigorous pulmonary
    toilet and rehabilitation, and continued
    bronchodilator therapy.
                 Renal
   Approximately 5% of the adult
    population have some degree of renal
    dysfunction that can affect the
    physiology of multiple organ systems
    and cause additional morbidity in the
    perioperative period. In fact, a
    preoperative creatinine level of 2.0
    mg/dL or higher is an independent risk
    factor for cardiac complications
   Identification of coexisting
    cardiovascular, circulatory, hematologic,
    and metabolic derangements secondary
    to renal dysfunction are the goals of
    preoperative evaluation in these
    patients
   A patient with known renal insufficiency
    undergoes a thorough history and
    physical examination with particular
    questioning about previous MI and
    symptoms consistent with ischemic
    heart disease. The cardiovascular
    examination seeks to document signs of
    fluid overload. The patient's functional
    status and exercise tolerance are
    carefully elicited.
   Diagnostic testing for patients with
    renal dysfunction include an
    electrocardiogram (ECG), serum
    chemistry panel, and complete blood
    count (CBC). If physical examination
    findings are suggestive of heart failure,
    a chest radiograph may be helpful
   Urinalysis and urinary electrolyte
    studies are not often helpful in the
    setting of established renal
    insufficiency, although they may be
    diagnostic in patients with new-onset
    renal dysfunction.
   Laboratory abnormalities are often seen
    in a patient with advanced renal
    insufficiency. Some metabolic
    derangements in a patient with
    advanced renal failure may be mild and
    asymptomatic and are revealed by
    electrolyte or blood gas analysis
   Anemia, when present in these patients,
    may range from mild and asymptomatic
    to that associated with fatigue, low
    exercise tolerance, and exertional
    angina. Such anemia can be treated with
    erythropoietin or darbepoietin
    preoperatively or perioperatively
   Because the platelet dysfunction
    associated with uremia is often a
    qualitative one, platelet counts are
    usually normal. A safe course is to
    communicate with the anesthesiologist
    the potential need for agents to be
    available in the operating room to assist
    in improving platelet function.
   Pharmacologic manipulation of
    hyperkalemia, replacement of calcium
    for symptomatic hypocalcemia, and the
    use of phosphate-binding antacids for
    hyperphosphatemia are often required.
   Sodium bicarbonate is used in the
    setting of metabolic acidosis not caused
    by hypoperfusion when serum
    bicarbonate levels are below 15 mEq/L.
    It can be administered in intravenous
    (IV) fluid as 1 to 2 ampules in a 5%
    dextrose solution
   Hyponatremia is treated by volume
    restriction, although dialysis is
    commonly required within the
    perioperative period for control of
    volume and electrolyte abnormalities
   Patients with chronic end-stage renal
    disease undergo dialysis before surgery
    to optimize their volume status and
    control the potassium level.
    Intraoperative hyperkalemia can result
    from surgical manipulation of tissue or
    transfusion of blood. Such patients are
    often dialyzed on the day after surgery
    as well
   Prevention of secondary renal insults in
    the perioperative period include the
    avoidance of nephrotoxic agents and
    maintenance of adequate intravascular
    volume throughout this period. In the
    postoperative period, the
    pharmacokinetics of many drugs may be
    unpredictable, and adjustments in dosage
    need to be made according to pharmacy
    recommendation.
   In the acute setting, patients who have
    stable volume status can undergo
    surgery without preoperative dialysis,
    provided that no other indication exists
    for emergency dialysis.
   Notably, narcotics used for
    postoperative pain control may have
    prolonged effects despite hepatic
    clearance, and nonsteroidal agents are
    avoided in patients with renal
    insufficiency.
Principles of Preoperative
 and Operative Surgery
         Sabiston 2007
     Presented in April 2008
      By Dr. S. Noorshafiee
SYSTEMS APPROACH TO
   PREOPERATIVE
    EVALUATION
          Hepatobiliary
   Hepatic dysfunction may reflect the
    common pathway of a number of insults
    to the liver, including viral-, drug-, and
    toxin-mediated disease. A patient with
    liver dysfunction requires careful
    assessment of the degree of functional
    impairment, as well as a coordinated
    effort to avoid additional insult in the
    perioperative period
   A history of any exposure to blood and
    blood products or exposure to
    hepatotoxic agents is obtained. Patients
    frequently know whether hepatitis has
    been diagnosed and need to be
    questioned about when the diagnosis
    was made and what activity led to the
    infection
   Although such a history may not affect
    further patient evaluation, it is
    important to obtain in case an operative
    team member is injured during the
    planned surgical procedure.
    A review of systems specifically
    inquires about symptoms such as
    pruritus, fatigability, excessive
    bleeding, abdominal distention, and
    weight gain. Evidence of hepatic
    dysfunction may be seen on physical
    examination
   Jaundice and scleral icterus may be
    evident with serum bilirubin levels
    higher than 3 mg/dL. Skin changes
    include spider angiomas, caput medusae,
    palmar erythema, and clubbing of the
    fingertips. Abdominal examination may
    reveal distention, evidence of fluid
    shift, and hepatomegaly.
    Encephalopathy or asterixis may be
    evident. Muscle wasting or cachexia can
    be prominent
   A patient with liver dysfunction
    undergoes standard liver function tests.
    Elevations in hepatocellular enzymes
    may suggest a diagnosis of acute or
    chronic hepatitis, which can be
    investigated by serologic testing for
    hepatitis A, B, and C. Alcoholic hepatitis
    is suggested by lower transaminase
    levels and an aspartate/alanine
    transaminase ratio (AST/ALT) greater
    than 2
   Laboratory evidence of chronic
    hepatitis or clinical findings consistent
    with cirrhosis is investigated with tests
    of hepatic synthetic function, notably
    serum albumin, prothrombin, and
    fibrinogen
   Patients with evidence of impaired
    hepatic synthetic function also have a
    CBC and serum electrolyte analysis.
    Type and screen is indicated for any
    procedure in which blood loss could be
    more than minimal.
   In the event of an emergency situation
    requiring surgery, such an investigation
    may not be possible. A patient with
    acute hepatitis and elevated
    transaminases is managed
    nonoperatively, when feasible, until
    several weeks beyond normalization of
    laboratory values.
   Urgent or emergency procedures in
    these patients are associated with
    increased morbidity and mortality. A
    patient with evidence of chronic
    hepatitis may often safely undergo
    surgery
   A patient with cirrhosis may be
    assessed with the Child-Pugh
    classification, which stratifies operative
    risk according to a score based on
    abnormal albumin and bilirubin levels,
    prolongation of the prothrombin time
    (PT), and the degree of ascites and
    encephalopathy
   This scoring system was initially applied
    to predict mortality in cirrhotic
    patients undergoing portacaval shunt
    procedures, although it has been shown
    to correlate with mortality in cirrhotic
    patients undergoing a wider spectrum of
    procedures as well.
   Although the figures may not represent
    current risk for all types of abdominal
    operations, little doubt exists that the
    presence of cirrhosis confers additional
    risk for abdominal surgery and that this
    risk is proportional to the severity of
    disease
   Other factors that affect outcomes in
    these patients are the emergency
    nature of a procedure, prolongation of
    the PT greater than 3 seconds above
    normal and refractory to correction
    with vitamin K, and the presence of
    infection
   Two common problems requiring surgical
    evaluation in a cirrhotic patient are
    hernia (umbilical and groin) and
    cholecystitis. An umbilical hernia in the
    presence of ascites is a difficult
    management problem because
    spontaneous rupture is associated with
    increased mortality rates.
   Elective repair is best after the ascites
    has been reduced to a minimum
    preoperatively, although the procedure
    is still associated with mortality rates
    as high as 14%.Repair of groin hernias in
    the presence of ascites is less risky in
    terms of both recurrence and mortality.
   Several recent reports have shown
    decreased rates of complication with
    laparoscopic procedures performed in
    cirrhotic patients. Among the best-
    described procedures is laparoscopic
    cholecystectomy performed in patients
    with Child's class A through C. When
    compared with open cholecystectomy,
    less morbidity in terms of blood loss and
    wound infection has been observed.
   Malnutrition is common in cirrhotic
    patients and is associated with a
    reduction in hepatic glycogen stores and
    reduced hepatic protein synthesis.
    Patients with advanced liver disease
    often have a poor appetite, tense
    ascites, and abdominal pain. Attention
    must be given to appropriate enteral
    supplementation, as done for all patients
    at significant nutritional risk.
             Endocrine
   A patient with an endocrine condition
    such as diabetes mellitus,
    hyperthyroidism or hypothyroidism, or
    adrenal insufficiency is subject to
    additional physiologic stress during
    surgery.
   The preoperative evaluation identifies
    the type and degree of endocrine
    dysfunction to permit preoperative
    optimization. Careful monitoring
    identifies signs of metabolic stress
    related to inadequate endocrine control
    during surgery and throughout the
    postoperative course.
   The evaluation of a diabetic patient for
    surgery assesses the adequacy of
    glycemic control and identifies the
    presence of diabetic complications,
    which may have an impact on the
    patient's perioperative course.
   The patient's history and physical
    examination document evidence of
    diabetic complications, including cardiac
    disease, circulatory abnormalities, and
    the presence of retinopathy,
    neuropathy, or nephropathy
   Preoperative testing may include fasting
    and postprandial glucose and hemoglobin
    A1c levels. Serum electrolyte, blood
    urea nitrogen, and creatinine levels are
    obtained to identify metabolic
    disturbances and renal involvement.
    Urinalysis may reveal proteinuria as
    evidence of diabetic nephropathy.
   An ECG is considered in patients with
    long-standing disease. The existence of
    neuropathy in diabetics may be
    accompanied by cardiac autonomic
    neuropathy, which increases the risk for
    cardiorespiratory instability in the
    perioperative period.
   A diabetic patient requires special
    attention to optimize glycemic control
    perioperatively. Non–insulin-dependent
    diabetics need to discontinue long-
    acting sulfonylureas such as
    chlorpropamide and glyburide because
    of the risk for intraoperative
    hypoglycemia; a shorter-acting agent or
    sliding-scale insulin coverage may be
    substituted in this period.
   The use of metformin is stopped
    preoperatively because of its
    association with lacticacidosis in the
    setting of renal insufficiency. An
    insulin-dependent diabetic is told to
    withhold long-acting insulin preparations
    (Ultralente preparations) on the day of
    surgery; lower dosages of intermediate-
    acting insulin (NPH or Lente) are
    substituted on the morning of surgery
   These patients are scheduled for early
    morning surgery, when feasible. During
    surgery, a standard 5% or 10% dextrose
    infusion is used with short-acting insulin
    or an insulin drip to maintain glycemic
    control
   A patient with diabetes mellitus that is
    well controlled by diet or oral
    medication may not require insulin
    perioperatively, but those with poorer
    control or patients taking insulin may
    require preoperative dosing and both
    glucose and insulin infusion during
    surgery
   Frequent assessments of glucose levels
    are continued through the postoperative
    period. Current recommendations are to
    maintain the perioperative glucose level
    between 80 and 150 mg/dL, even in
    patients not previously diagnosed as
    being diabetic. Adequate hydration must
    be maintained with avoidance of
    hypovolemia.
   Postoperative orders include frequent
    (every 2-4 hours) finger stick glucose
    checks and the use of short-acting
    insulin in the form of sliding-scale
    coverage. Twice-daily doses of
    intermediate-acting insulin can be
    supplemented with sliding-scale
    coverage until the patient is eating and
    can resume the usual regimen
   Postoperative cardiac events can occur
    with unusual manifestations in these
    patients. Although chest pain needs to
    be evaluated with ECG and serum
    troponin levels, this same evaluation may
    need to be done for new-onset dyspnea,
    blood pressure alterations, or a
    decrease in urine output
   Adequate prophylaxis for deep venous
    thrombosis (DVT) is essential because
    of the increased risk for thrombosis.
    The adequacy of perioperative glycemic
    control has an impact on wound healing
    and the risk for surgical site infection
         Perioperative Diabetic
              Management
   Management of diabetic patients has
    evolved over the past several years. The
    introduction of new drugs for non–
    insulin-dependent diabetics, in addition
    to new types of insulin and new insulin
    delivery systems in insulin-dependent
    diabetics, has changed the way that
    these patients are approached in the
    perioperative period.
   Rapid-acting (Lispro) and short-acting
    (Regular) insulin preparations are usually
    withheld when the patient stops oral
    intake (NPO) and are used for acute
    management of hyperglycemia during
    the NPO period
   intermediate-acting (NPH Lente) and long-
    acting (Ultralente, Glargine) insulin
    preparations are administered at two thirds
    the normal pm dose the night before surgery
    and half the normal am dose the morning of
    surgery, with frequent bedside glucose
    determinations and treatment with short-
    acting insulin as needed. An infusion of 5%
    dextrose is initiated the morning of surgery
   If the planned procedure is expected to
    take a long time, an insulin infusion can
    be administered, again with frequent
    monitoring of blood glucose.
Insulin pumps are used by some patients
  as their method of glucose management.
  These pumps use short-acting insulin
  and have a variable delivery rate that
  can be programmed to more closely
  simulate endogenous insulin production
   On the day of surgery, the patient
    continues with the basal insulin infusion.
    The pump is then used to correct the
    glucose level as it is measured. Patients
    generally have a correction or
    sensitivity factor that will decrease
    their glucose by 50 mg/dL. It is
    important to know this factor before
    the planned surgical procedure so that
    glucose can be managed in the operating
    room
   Patients who take oral hypoglycemic agents
    typically withhold their normal dose the day
    of surgery. Patients can resume their oral
    agent once diet is resumed. Coverage for
    hyperglycemia is with a short-acting insulin
    preparation based on blood glucose
    monitoring. An exception is metformin. If
    the patient has altered renal function, this
    agent needs to be discontinued until renal
    function either normalizes or stabilizes.
   patient with known or suspected thyroid
    disease is evaluated with a thyroid
    function panel. Evidence of
    hyperthyroidism is addressed
    preoperatively and surgery deferred
    until a euthyroid state is achieved, when
    feasible
   These patients need to have their
    electrolyte levels determined and an
    ECG performed as part of their
    preoperative evaluation. In addition, if
    the physical examination suggests signs
    of airway compromise, further imaging
    may be warranted
   A patient with hyperthyroidism who
    takes antithyroid medication such as
    propylthiouracil or methimazole is
    instructed to continue this regimen on
    the day of surgery
   The patient's usual doses of β-blockers
    or digoxin are also continued. In the
    event of urgent surgery in a thyrotoxic
    patient at risk for thyroid storm, a
    combination of adrenergic blockers and
    glucocorticoids may be required and are
    administered in consultation with an
    endocrinologist
   Patients with newly diagnosed
    hypothyroidism generally do not require
    preoperative treatment, although they
    may be subject to increased sensitivity
    to medications, including anesthetic
    agents and narcotics
   Severe hypothyroidism can be
    associated with myocardial dysfunction,
    coagulation abnormality, and electrolyte
    imbalance, notably hypoglycemia. Severe
    hypothyroidism needs to be corrected
    before elective operations
           Hematologic
   Hematologic assessment may lead to the
    identification of disorders such as
    anemia, inherited or acquired
    coagulopathy, or a hypercoagulable
    state. Substantial morbidity may derive
    from failure to identify these
    abnormalities preoperatively. The need
    for perioperative prophylaxis for venous
    thromboembolism must be carefully
    reviewed in every surgical patient.
   Anemia is the most common laboratory
    abnormality encountered in preoperative
    patients. It is often asymptomatic and
    can require further investigation to
    understand its cause. The history and
    physical examination may uncover
    subjective complaints of energy loss,
    dyspnea, or palpitations, and pallor or
    cyanosis may be evident
   Patients are evaluated for
    lymphadenopathy, hepatomegaly, or
    splenomegaly, and pelvic and rectal
    examinations are performed. A CBC,
    reticulocyte count, and serum iron, total
    iron-binding capacity, ferritin, vitamin
    B12, and folate levels are obtained to
    investigate the cause of anemia.
   The decision to transfuse a patient
    perioperatively is made with
    consideration of the patient's
    underlying risk factors for ischemic
    heart disease and the estimated
    magnitude of blood loss during surgery.
   Generally, patients with normovolemic
    anemia without significant cardiac risk
    or anticipated blood loss can be
    managed safely without transfusion,
    with most healthy patients tolerating
    hemoglobin levels of 6 or 7 g/dL
  Guidelines for Red Blood Cell
Transfusion for Acute Blood Loss
 Evaluate the risk for ischemia
 Estimate/anticipate the degree of
  blood loss. Less than 30% rapid volume
  loss probably does not require
  transfusion in a previously healthy
  individual
   Measure the hemoglobin concentration:
    <6 g/dL, transfusion usually required; 6-
    10 g/dL, transfusion dictated by clinical
    circumstance; >10 g/dL, transfusion
    rarely required
   Measure vital signs/tissue oxygenation
    when hemoglobin is 6-10 g/dL and the
    extent of blood loss is unknown.
    Tachycardia and hypotension refractory
    to volume suggest the need for
    transfusion; O2 extraction ratio >50%,
    decreased Vo2, suggest that
    transfusion is usually needed
   All patients undergoing surgery are
    questioned to assess their bleeding risk.
    Coagulopathy may result from inherited
    or acquired platelet or factor disorders
    or may be associated with organ
    dysfunction or medications
   The inquiry begins with direct
    questioning about a personal or family
    history of abnormal bleeding.
    Supporting information includes a
    history of easy bruising or abnormal
    bleeding associated with minor
    procedures or injury.
   A history of liver or kidney dysfunction
    or recent common bile duct obstruction
    needs to be elicited, as well as an
    assessment of nutritional status.
    Medications are carefully reviewed, and
    the use of anticoagulants, salicylates,
    nonsteroidal anti-inflammatory drugs
    (NSAIDs), and antiplatelet drugs are
    noted
   Physical examination may reveal
    bruising, petechiae, or signs of liver
    dysfunction.
   Patients with thrombocytopenia may
    have qualitative or quantitative defects
    as a result of immune-related disease,
    infection, drugs, or liver or kidney
    dysfunction.
   Qualitative defects may respond to
    medical management of the underlying
    disease process, whereas quantitative
    defects may require platelet
    transfusion when counts are less than
    50,000 in a patient at risk for bleeding
   Although coagulation studies are not
    routinely ordered, patients with a
    history suggestive of coagulopathy
    undergo coagulation studies before
    surgery. Coagulation studies are also
    obtained before the procedure if
    considerable bleeding is anticipated or
    any significant bleeding would be
    catastrophic.
   Patients with documented disorders of
    coagulation may require perioperative
    management of factor deficiencies,
    often in consultation with a
    hematologist
   Patients receiving anticoagulation
    therapy usually require preoperative
    reversal of the anticoagulant effect. In
    patients taking warfarin, the drug is
    withheld for four scheduled doses
    preoperatively to allow the international
    normalized ratio (INR) to fall to the
    range of 1.5 or less (assuming that the
    patient is maintained at an INR of 2.0-
    3.0).
   Additional recommendations for specific
    diagnoses requiring chronic
    anticoagulation are based on risk-
    benefit analysis. Patients with a recent
    history of venous thromboembolism or
    acute arterial embolism frequently
    require perioperative IV heparinization
    because of an increased risk for
    recurrent events in the perioperative
    period
   Systemic heparinization can often be
    stopped within 6 hours of surgery and
    restarted within 12 hours
    postoperatively. When possible, surgery
    is postponed in the first month after an
    episode of venous or arterial
    thromboembolism. Patients taking
    anticoagulants for less than 2 weeks for
    pulmonary embolism (PE) or proximal
    DVT are considered for inferior vena
    cava filter placement before surgery
   All surgical patients are assessed for
    their risk for venous thromboembolism
    and receive adequate prophylaxis
    according to current guidelines.Patients
    are questioned to elicit any personal or
    family history suggestive of a
    hypercoagulable state. Levels of protein
    C, protein S, antithrombin III, and
    antiphospholipid antibody can be
    obtained
   Risk factor stratification is achieved by
    considering multiple factors, including
    age, type of surgical procedure,
    previous thromboembolism, cancer,
    obesity, varicose veins, cardiac
    dysfunction, indwelling central venous
    catheters, inflammatory bowel disease,
    nephrotic syndrome, pregnancy, and
    estrogen or tamoxifen use.
   A number of regimens may be
    appropriate for prophylaxis of venous
    thromboembolism, depending on
    assessed risk.Such regimens include the
    use of unfractionated heparin, low-
    molecular-weight heparin, intermittent
    compression devices, and early
    ambulation. Initial prophylactic doses of
    heparin can be given preoperatively,
    within 2 hours of surgery.
    ADDITIONAL PREOPERATIVE
        CONSIDERATIONS
   Older adults account for a
    disproportionate percentage of surgical
    patients. Risk assessment must
    carefully consider the effect of
    comorbid illness in this population.
    Although age has been reported as an
    independent risk factor for
    postoperative mortality, this
    observation may represent the
    unmeasured aspects of comorbid
    disease and the severity of illness.
   In an older adult patient, the
    preoperative evaluation seeks to
    identify and quantify the magnitude of
    comorbid disease and optimize the
    patient's condition before surgery when
    possible. Preoperative testing is based
    on findings suggested in the history and
    physical examination.
   Generally, elderly patients have an ECG,
    chest radiograph, CBC, and
    determination of glucose, creatinine,
    blood urea nitrogen, and albumin levels.
    Additional preoperative studies are
    based on the criteria discussed earlier
    for evaluation of patient and procedural
    risk.
   Predicting and preventing postoperative
    delirium are important aspects of the
    perioperative care of the elderly.
    Patients with three or more of the
    following have a 50% risk for
    postoperative delirium:
   70 years or older; self-reported alcohol
    abuse; poor cognitive status; poor
    functional status; markedly abnormal
    preoperative serum sodium, potassium,
    or glucose level; noncardiac thoracic
    surgery; and aortic aneurysm surgery.
   This risk is explained to the patient and
    the family along with the symptoms of
    postoperative delirium. If delirium does
    occur, metabolic and infectious causes
    need to be investigated before labeling
    the event as sundowning.
          Nutritional Status
   Evaluation of the patient's nutritional
    status is part of the preoperative
    evaluation. A history of weight loss
    greater than 10% of body weight over a
    6-month period or 5% over a month is
    significant.
   Albumin or prealbumin levels and immune
    competence (as assessed by delayed
    hypersensitivity reaction) may help
    identify patients with some degree of
    malnutrition, and physical findings of
    temporal wasting, cachexia, poor
    dentition, ascites, or peripheral edema
    may be corroborative. The degree of
    malnutrition is estimated on the basis of
    weight loss, physical findings, and
    plasma protein assessment
   The adequacy of a nutritional regimen
    can be confirmed with a number of
    serum markers. Albumin (half-life, 14-18
    days), transferrin (half-life, 7 days),
    and prealbumin (half-life, 3-5 days)
    levels can be determined on a regular
    basis in hospitalized patients.
   These proteins are responsive to stress
    conditions, however, and their synthesis
    may be inhibited in the immediate
    perioperative period. Once a patient is
    on a stable regimen and in the anabolic
    phase of recovery, these markers
    reflect the adequacy of nutritional
    efforts.
   The effect of perioperative nutritional
    support on outcomes has been studied in
    a number of trials.
   Patients with severe malnutrition (as
    defined by a combination of weight loss,
    visceral protein indicators, and
    prognostic indices) appear to benefit
    most from preoperative parenteral
    nutrition, as demonstrated in study
    groups treated with total parenteral
    nutrition for 7 to 10 days before
    surgery for gastrointestinal malignancy
   The majority of studies show a
    reduction in the rate of postoperative
    complications from approximately 40%
    to 30%. The use of total parenteral
    nutrition postoperatively in similar
    groups of patients is associated with an
    approximately 10% increase in
    complication rates
   Well-nourished patients undergoing
    surgery do not appear to benefit from
    aggressive perioperative nutritional
    support; parenteral nutrition is
    additionally associated with increased
    septic complications.
   Generally, nutritional support begins
    within 5 to 10 days after surgery in all
    patients unable to resume their normal
    diet. Such support may take the form of
    nasoenteric feeding, parenteral
    nutrition, or a combination of the two
                  Obesity
   The perioperative mortality rate is
    significantly increased in patients with
    clinically severe obesity (body mass
    index [BMI] >40 kg/m2 or BMI >35
    kg/m2 with significant comorbid
    conditions). The goal of preoperative
    evaluation of an obese patient is to
    identify risk factors that might modify
    perioperative care of the patient.
   Clinically severe obesity is associated
    with a higher frequency of essential
    hypertension, pulmonary hypertension,
    left ventricular hypertrophy, congestive
    heart failure, and ischemic heart
    disease
   Patients with no or one of these risk
    factors receive a β-blocker
    preoperatively for cardioprotection.
    Patients with two or more risk factors
    undergo noninvasive cardiac testing
    preoperatively
   Obesity is also a risk factor for
    postoperative wound infection. The rate
    of wound infections is much lower with
    laparoscopic surgery in this group, which
    could have a bearing on selection of the
    operative approach. Obesity is an
    independent risk factor for DVT and PE;
    therefore, appropriate prophylaxis is
    instituted in these patients.
    PREOPERATIVE CHECKLIST
   preoperative evaluation concludes with a
    review of all pertinent studies and
    information obtained from investigative
    tests. Documentation of this review is
    made in the chart, which represents an
    opportunity to ensure that all necessary
    and pertinent data have been obtained
    and appropriately interpreted
   Informed consent after discussion with
    the patient and family members
    regarding the indication for the
    anticipated surgical procedure, as well
    as its risks and proposed benefits, are
    documented in the chart. The
    preoperative checklist also gives the
    surgeon an opportunity to review the
    need for β-blockade, DVT prophylaxis,
    and prophylactic antibiotics.
   Preoperative orders are written and
    reviewed. The patient receives written
    instructions regarding the time of
    surgery and management of special
    perioperative issues such as fasting,
    bowel preparation, and medication use.
       Antibiotic Prophylaxis
   Appropriate antibiotic prophylaxis in
    surgery depends on the most likely
    pathogens encountered during the
    surgical procedure. The type of
    operative procedure is helpful in
    deciding the appropriate antibiotic
    spectrum and is considered before
    ordering or administering any
    preoperative medication.
   Prophylactic antibiotics are not
    generally required for clean (class I)
    cases, except in the setting of
    indwelling prosthesis placement or when
    bone is incised. Patients who undergo
    class II procedures benefit from a
    single dose of an appropriate antibiotic
    administered before the skin incision.
   For abdominal (hepatobiliary,
    pancreatic, gastroduodenal) cases,
    cefazolin is generally used.
    Contaminated (class III) cases require
    mechanical preparation or parenteral
    antibiotics with both aerobic and
    anaerobic activity.
   Such an approach is taken in the setting
    of emergency abdominal surgery, as for
    suspected appendicitis, and in trauma
    cases. Dirty or infected cases often
    require the same antibiotic spectrum,
    which can be continued into the
    postoperative period in the setting of
    ongoing infection or delayed treatment.
The appropriate antibiotic is chosen
 before surgery and administered before
 the skin incision is made Repeat dosing
 occurs at an appropriate interval, usually
 3 hours for abdominal cases or twice
 the half-life of the antibiotic, although
 the patient's renal function may alter
 the timing
   Perioperative antibiotic prophylaxis
    generally is not continued beyond the
    day of surgery. With the advent of
    minimal-access surgery, the use of
    antibiotics seems less justified because
    the risk for wound infection is
    extremely low.
   For example, routine antibiotic
    prophylaxis in patients undergoing
    laparoscopic cholecystectomy for
    symptomatic cholelithiasis is of
    questionable value. It may have a role,
    however, in cases that result in
    prosthetic graft (i.e., mesh) placement,
    such as laparoscopic hernia repair.
    Preoperative Mechanical Bowel
               Cleansing
   Mechanical bowel preparation with the
    addition of oral antibiotics was the
    standard of care for several decades
    for any intestinal surgery. More recent
    studies have evaluated the need for
    both oral antibiotics and mechanical
    cleansing
   Oral antibiotics confer no benefit to
    the patient and may increase the risk
    for postoperative infection with
    Clostridium difficile. In addition,
    although it seems intuitive that removal
    of bulk fecal material would decrease
    the risk for anastomotic and infectious
    complications, the opposite is true.
   A recent meta-analysis showed that
    both of these events are not decreased
    and may be increased with mechanical
    cleansing.
       Review of Medications
   Careful review of the patient's home
    medications is a part of the
    preoperative evaluation before any
    operation; the goal is to appropriately
    use medications that control the
    patient's medical illnesses while
    minimizing the risk associated with
    anesthetic-drug interactions or the
    hematologic or metabolic effects of
    some commonly used medications and
    therapies
   The patient is asked to name all
    medications, including psychiatric drugs,
    hormones, and alternative/herbal
    medications, and to provide dosages and
    frequency.
   In general, patients taking cardiac
    drugs, including β-blockers and
    antiarrhythmics, pulmonary drugs such
    as inhaled or nebulized medications, or
    anticonvulsants, antihypertensives, or
    psychiatric drugs are advised to take
    their medications with a sip of water on
    the morning of surgery.
   Parenteral forms or substitutes are
    available for many drugs and may be
    used if the patient remains NPO for any
    significant period postoperatively. It is
    important to return patients to their
    normal medication regimen as soon as
    possible
   Two notable examples are the additional
    cardiovascular morbidity associated
    with the perioperative discontinuation
    of β-blockers and rebound hypertension
    with abrupt cessation of the
    antihypertensive clonidine. Medications
    such as lipid-lowering agents or vitamins
    can be omitted on the day of surgery.
   Some drugs are associated with an
    increased risk for perioperative
    bleeding and are withheld before
    surgery. Drugs that affect platelet
    function are withheld for variable
    periods: aspirin and clopidogrel (Plavix)
    are withheld for 7 to 10 days, whereas
    NSAIDs are withheld between 1 day
    (ibuprofen and indomethacin) and 3 days
    (naproxen and sulindac), depending on
    the drug's half-life
   Because the use of estrogen and
    tamoxifen has been associated with an
    increased risk for thromboembolism,
    they probably need to be withheld for a
    period of 4 weeks preoperatively
   The widespread use of herbal
    medications has prompted review of the
    effects of some commonly used
    preparations and their potential adverse
    outcomes in the perioperative period.
    These substances may fail to be
    recorded in the preoperative evaluation,
    although important metabolic and
    hematologic effects can result from
    their regular use
   Generally, the use of herbal medications
    is stopped preoperatively, but this
    needs to be done with caution in
    patients who report the use of valerian,
    which may be associated with a
    benzodiazepine-like withdrawal
    syndrome.
        Preoperative Fasting
   The standard order of ―NPO past
    midnight‖ for preoperative patients is
    based on the theory of reduction of
    volume and acidity of the stomach
    contents during surgery. Recently,
    guidelines have recommended a shift to
    allow a period of restricted fluid intake
    up to a few hours before surgery
   The ASA recommends that adults stop
    intake of solids for at least 6 hours and
    clear fluids for 2 hours. When the
    literature was recently reviewed by the
    Cochrane group, they found 22 trials in
    healthy adults that provided 38
    controlled comparisons.
   Very few trials investigated the fasting
    routine in patients at higher risk for
    regurgitation/aspiration (pregnant,
    elderly, obese, or those with stomach
    disorders). There is also increasing
    evidence that preoperative
    carbohydrate supplementation is safe
    and may improve a patient's response to
    perioperative stress
   There was no evidence that the volume
    or pH of gastric contents differed with
    the length and type of fasting. Though
    not reported in all the trials, there did
    not appear to be an increased risk for
    aspiration/regurgitation with a
    shortened period of fasting.
   Surgeons and anesthesiologists should
    evaluate the evidence and consider
    adjusting their standard fasting
    policies.

								
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