preoperative evaluation for residents of anesthesia part 2
TRANSCRIPT
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