preoperative evaluation for residents of anesthesia part 2

Mansoor Masjedi MD , FCCMGrand round of anesthesia dept.,

SUMS , Nov. 2013

A brief review

abcd

AsthmaA chronic inflammatory disease characterized

by obstruction of the airways that is partially or completely reversible with Rx or spontaneously

Patients with mild, well-controlled asthma have no greater risk associated with anesthesia and surgery than normal individuals do

AsthmaO2 saturation by pulse oximetry is usefulABG only in severe acute exacerbationDDx. of Wheezing

COPD GERD Vocal cord dysfunction Tracheal or bronchial stenosis Cystic fibrosis ABPA Heart failure

AsthmaSpirometry is the preferred diagnostic test, but a

normal result does not exclude asthma (strong suspicion → methacholine challenge test or a trial of bronchodilator therapy )

PFTs have no perioperative predictive value but in rare instances may be useful to gauge the severity of disease or the adequacy of therapy

Preop Chest X-ray is necessary only for evaluation of infections or pneumothorax

COPD

Presence of symptoms on most days for at least 3 months for 2 successive years

oror recurrent excessive sputum that severely

impairs expiratory airflow

An acute exacerbation is defined as an increase in symptoms that requires a change in management

COPDFEV1↓ , FVC↑ , DLCO↓

PFT :not shown to predict periop outcome

C-xray : useful only when infection is suspected

ECG show: RAD , RBBB, or peaked P waves

Restrictive pulmonary disorders

Pulmonary : lung resection , pulmonary fibrosis, ILD

Extrapul. : kyphoscoliosis , obesity , AS , Myasth.gravis, pleural efusion, Pneumothorax

FEV1 and FVC are reduced proportionally, so the ratio is normal

Dyspnea

Chronic dyspnea of unclear etiology ,4 major DDx.: asthma COPD interstitial lung disease cardiac dysfunction

Dyspnea

Hx. & P/E → accurate dx in 2/3 of cases Initial testing may include:

ECG Htc (to exclude anemia) ABG TFT C-xray Spirometry oximetry at rest and while walking several feet

BNP levels may be useful. Heart failure : BNP >400 pg/mLPTE & cor pulmonale :BNP between 100 - 400

pg/mL

Surprisingly absent predictors in this list are asthma and results from ABG or PFTs

Prescriptions for antibiotics, bronchodilators, and steroids, referral to pulmonologists or internists, and postponing surgery are important in patients at high risk

Pulmonary Hypertension

Persistent Mean PAP> 25 mm Hg with a PAOP <15 mm Hg

Occult PH is more problematic than fully recognized disease because symptoms may be attributed to other diseases and periop decompensation may occur unexpectedly

Patients with PAH have a high rate of periop morbidity and mortality

Pulmonary Arterial Hypertension Primary pulmonary hypertension

Sporadic Familial

Associated with Collagen vascular disease Congenital shunts Portal hypertension HIV Drugs/toxins Persistent pulmonary hypertension of the newborn

Pulmonary Venous Hypertension Left-sided heart disease Extrinsic compression of central pulmonary veins Pulmonary veno-occlusive disease

Pulmonary Hypertension Related to Lung Disease or Hypoxemia Chronic obstructive pulmonary disease Interstitial lung disease Sleep-disordered breathing Neonatal lung disease Chronic exposure to high altitude

Pulmonary Hypertension Caused by Chronic Thromboembolic Disease Pulmonary thrombosis or embolism Sickle cell disease

Pulmonary Hypertension from Disorders Directly Affecting the Pulmonary Vasculature

Schistosomiasis Sarcoidosis

Pulmonary Hypertension Signs and symptoms of disease severity include:

• Dyspnea at rest • Metabolic acidosis • Hypoxemia • Right HF(peripheral edema, hepatomegaly, ↑JVP) • Hx of syncope

Echo : screening test of choice

ECG: RAD, RBBB, RVH, tall R in V1 & V2, P pulmonale (leads II, III, aVF, and V1)

Smokers and Those Exposed to Second-Hand Smoke

Active and passive smokers

↑ risk of periop resp. complications

Soon after a patient quits smoking carbon monoxide ↓ Cyanide ↓ Lower nicotine levels improve

vasodilation many toxic substances that impair

wound healing decreaseBuproprion or clonidine should be started 1 to 2 wks before an attempt at quitting; nicotine

replacement therapy is effective immediately

Endocrine Disorders

Diabetes Mellitus In the United States, 20 million

diabetics , with 1 million new each year

Females twice as commonly as in males

Diabetic without known CAD or angina = a nondiabetic with a previous MI for the risk of myocardial ischemia or cardiac death

Autonomic neuropathy is the best

predictor of silent ischemia

Aggressive management of hyperglycemia decreases postop complications

Diabetes MellitusThe combination of HTN, diabetes, and age >55 yr

accounts for more than 90% of pts with renal insufficiency

Screening for kidney disease is accepted

Poorly controlled diabetes →risk for the development of stiff joint syndrome→reduced cervical mobility → Diff. Airway ?

ECG ,electrolytes, BUN, Cr. , and BS is recommended for all diabetic patients

Target FBS <110 mg/dL in noncritically ill hospitalized patients

Steroid

Renal Disease

Renal Disease

Chronic kidney disease (CKD) : GFR <60 mL/min/1.73 m2) for at least 3 months or significant proteinuria

CRF : GFR < 15 mL/min/1.73 m2ARF: Urine output <0.5 mL/kg/hrESRD :loss of renal function ≥ 3 mo

CKD : a significant risk factor for cardiovascular morbidity and mortality (considered to be equal to angina, MI, or a history of known CAD)

Renal DiseaseValvular heart disease is common in pts undergoing

maintenance dialysis

Pulmonary hypertension and increased cardiac output occur in many patients with an arteriovenous fistula

Preexisting renal insufficiency + diabetes + contrast medium → risk of renal failure may be as high as 12% to 50%.

ACEIs and ARBs prevent deterioration in patients with diabetes or renal insufficiency but may worsen function during hypoperfusion states

LMWHs are cleared by the kidneys and are not removed during dialysis

All Forms of Liver Diseasebilirubin >2.5 mg/dL → icterus can be seen in

mucous membranes and sclerae

Reduction of ascites preop→ ↓risk of wound dehiscence and improve pulmonary function

Na restriction (in diet and IV solutions), diuretics (esp. spironolactone, which inhibits aldosterone), and even paracentesis are useful.

Coagulopathies Prolonged PT (without a hx of warfarin)→ the

most common cause is lab. error, liver disease, or malnutrition

Prolonged aPTT can result from both hypocoagulable and hypercoagulable cond.

The most common cause of a prolonged aPTT other than heparin exposure is vWD

Thrombocytopenia

Surgery can be performed safely in patients with platelet >50,000/mm3

Centroneuraxial anesthesia is safe with plt >100,000/mm3

Thrombocytosis Plt >500,000/mm3 and may be:

physiologic (exercise, pregnancy) primary (myeloproliferative disorder)secondary (iron deficiency, neoplasm, surgery, chronic

inflammation)

Plt >1,000,000/mm3 →risk for thrombotic events such as stroke, MI, pulmonary and mesenteric emboli, and peripheral arterial and venous clots

Neurologic Diseases

Preop evaluation focuses on the pulmonary system and degree of disability, especially dysphagia

and dyspnea. Determination of room-air saturation and orthostatic

BP and HR is important

URTI & anaesthesiaMild symptoms - can usually proceed

huge inconvenience to patient if cancelled

Severe symptoms (purulent secretions, productive cough, T > 38°C, or signs of pulmonary involvement)Postpone 4 wks

Intermediate severity - ? ? risk of increased bronchial reactivity

Additional risk factors :hx of asthma, need for intubation, surgery on the airway, smoking hx, and a hx of prematurity in pediatric patients

Dr. Andrew Ferguson

Preoperative Evaluation of Morbidly Obese PatientsObesityPresent difficult intubation.Perioperative basal lung collapse leading to

postoperative hypoxia.History of sleep apnoea may lead to post-

operative airway compromise.Ideally obese patients should lose weight

preoperatively, and co-existent diabetes and hypertension stabilised

Preoperative Evaluation of Patients with Allergies

Anaphylactic and anaphylactoid reactions during anesthesia =1 in 6000

Muscle relaxants :69%latex (12%) and Antibiotics (8%)

Fasting GuidelinesTime before anaesthesia Food or fluid intake

Up to 8 hours Unrestricted

Up to 6 hours Light meal

Up to 4 hours Breast milk

Up to 2 hours Clear liquids only (no solids, no fat)

2 hours pre-anaesthesia Nothing permitted

Dr. Andrew Ferguson

Preoperative Planning for Postoperative Pain ManagementPain ReliefMethod of postoperative analgesia should be in

mind.Allows deep breathing and coughing and

mobilisation.Prevent secretion retention and lung collapse.Reduces the incidence of postoperative

pneumonia.Epidurals appear particularly good at this for

abdominal and thoracic surgical procedures.

Preoperative consultationRisk stratificationRisk modificationplanning periop pt management

Ideally, the medical consultants who are part of the periop evaluation should be the same individuals who provide continuing care for the pt.

What is the diagnosis? How was it determined?

Are additional studies required for a more precise determination?

Is the patient's condition optimized?

Should any specific recommendations be made for postop management and follow-up?

امام علی )ع( با تشریح سه اصل مهم پزشکی می فرمایند :

"هر که طبابت کند باید "سعی خود را به کار بردو خیرخواه باشد و از خدا بترسد

Thanks for your patience

&Have a nice weekend