Preoperative Evaluation and Postoperative Management

CHAP .19 Preoperative Evaluation and Postoperative Management

99. 5 .4

1st year resident, Noh Jae Hong

Management of Medical Problems

ENDOCRINE DISEASE

1. Diabetes Mellitus

most common endocrine disease

-- uncontrolled DM : morbidity : 2times

mortality : 3 times

-- MI risk of females with NIDDM : 4times

-- DM duration more than 20yrs, nephropathy : 50%

hypertension : 70%

-- increased risk of acute renal failure, after iv contrast

s-Cr >2.0

vascular disease

onset of DM < 40yrs

-- autonomic neuropathy --> increased risk of MI,(intraoperative hypotension, cardiac arrythmia)

sudden death

decreased esophageal and intestinal motility

delayed gastric emptying

increased risk of aspiration pneumonitis

-- infection --> G(-), staphylococcal pneumonia

G(-) & Group B Streptococcus sepsis 7% (1% of normal population)

sepsis is mc caused by E.coli from urinary tract

-- wound dehiscence, infection, decreased amounts of collagen formation, fibroblast growth

capillary growth : 10.7% : 1.8%

-- Goal of treatment : avoiding ketosis, hyperglycemia, hypoglycemia

-- admit pts 2days prior to surgery

begin insulin drip at 1-3U/hr

initially, glucose monitored every 1-2hrs

after 100-200mg/dl range, monitor every 4hrs

-- Type 2 DM

controlled with hypoglycemics or diet : iv fluid containing no dextrose should not given insulin

RI : BST>250mg/dl

pts taking long acting sulfonylurea ---> discontinued 3days prior to surgery

" short " ---> " 1days "

-- Type 1 DM

1/3~1/2 of pts usual daily dose of NPH is given subcutaneously the morning of surgery

intra- or postop insulin should be delivered iv, as a continuous drip or intermittent (q6hrs)

sc bolus of RI with 5% dextrose

-- periop hypoglycemia : coma

periop hyperglycemia (250mg/dl): infection, poor wound healing, electrolyte abnomalities, hyperosmolar coma,

ketoacidosis

-- postop BST q 6hrs until eating

maintain BST<250mg/dl , RI should be given on a sliding scale

-- regional anesthesia : lower stress-induced hyperglycemia

-- thrombotic complication : enhanced plt aggregation and TXA2 production

improved glycemic control and low-dose aspirin may correct the plt function

2. HYPERTHYROIDISM

Graves' ds is mc cause of hyperthyroidism

F:M = 10:1

[ Preoperative management ]

* PTU : at least 2wks before surgery

100-200mg q6hrs along with beta blocker

--> inhibit tyroglobulin iodination and iodotyrosine couling recuce extrathyroidal conversion of T4 to T3

* SSKI(saturated solution of potassium iodide) : 6-12 drops *2/d for 10-14days prior to surgery

* hydrocortisone : 100mg q8hrs --> decrease extrathroidal conversion of T4 to T3

* propranolol : 10-80mg q6-8hrs

[ Treatment of tyroid storms ]

1) PTU

2) invasive hemodynamic monitoring and crystalloid therapy

3) O2

4) mechanical cooling devices

5) avoidance of aspirin, atropine, methoxyflurame, cyclopropane

3. HYPOTHROIDSIM

over 50% of all cases are caused by previous thyroid surgery or RI therapy

* symptoms : lethargy, dry skin, memory impairment, apathy, hoarseness,

periorbital edma, goiter, brittle hair, increased relaxation phase of DTR

constipation, cardiomegaly, pleural effusion, pericardial effusion, ascites

* preop preparation : slow replacement with levothyroxine

if given too quickly, may cause cardiovascular collapse

* tyroid replacement therapy : 0.025mg of tyroxin daily, doubled every 2weeks until the patients

taking a dose of 0.15mg daily

TSH level will determine the daily dose

in severe myxedematous pts : 0.3-0.5mg tyroxin given in iv

hydrocortisone (100-300mg q8hrs)

Cx: hypoglycemia, anemia, hypothermia, hyponatremia

increased incidence of intraop hypotension, increased rates of CRF, ileus after abdominal surgery

4. ADRENAL INSUFFICIENCY/IATROGENIC STEROID USE

should be DDX for periop hypertension

ACTH stimulation test : ACTH 25u given

normal : cortisol level : absolute rise >7ug or total >18ug doubling of the basal line

Empirical coverage with a "stress" dose of hydrodortisone is recommended 100-300mg q8hrs

pts on chronic steroid supression or Addison's ds

① hydrocortisone : 100mgIM in OR

" : 50mg IM/IV in recovery room q6hrs for 3 dose

" : 25mg IM/IV q6hrs for 4doses if pts hemodynamically stable

② taper to maintenance dosage over next 3-5days

havles the dose of hydrocortisone until a dose of 25mg is reached

eliminating one daily dose each day until the drug has been stopped

③ increase cortisol dosage to 200-400mg over 24hrs if hypotension

CADIOVASCULAR DISEASE

Preoperative Evaluation

* History : known heart ds, DM, hyperlipidemia, hypertension, smoking, strong family history of heart ds

* P/E : hypertension , JVE, lateral displaced point of maximal impulse, irregular pulse, S3,

pulmonay rales, murmurs, peripheral edema, bruits

* LAB : anemia,

K, Na : important in taking diuretics and digitalis

BUN/Cr : renal fx, hydration status

Glucose : duciagnosed DM

CXR, ECG

1. CORONARY ARTERY DISEASE

-- incidence of MI after surgery : 0.15%

-- prior MI, reinfarction rate : 5%

after 3mo : 30%, 3-6mo : 12%, 6mo = no prior history of IHD

-- postop MI mortality : 50%

Table 19.8

-- degree of LV dysfucntion is more critical

Exercise stress test : pts who has IHD not manifested when at rest

ischemic ECG + < 75% of maximal predicted HR ---> MI :25% mortality : 18.5%

---> selectively apply to a high risk population

Dipyridamole-thallium scan

-- high degree of sensitivity and specificity

-- dipyridamole to dilate normal vs but not stenotic vs

hypoperfused myocardium does not uptake 5min after injection

reperfusion and uptake of thalium 3hrs after injection : viable but high risk myocardium

-- periop MI risk 20-33% in pts with reperfusion

Resting gated blood pool

-- postop MI : 19% in EF>35%

-- postop MI : 75% in EF<35%

-- 2/3 of postop MI occur during first 3days

-- chest pain : 90% of nonsurgical pts with MI

50% of surgical pts with MI d/t coexisting pain and analgesia

suspision for postop MI is extremely important

-- CK-MB isoenzyme level is most sensitive and specific indicator of MI

-- routine postop ECG on all pts with cardiovascular ds is controversial

if routine screening of asymptomatic pts is desired, ECG should be obtained 24hrs following surgery

-- supplemental O2

-- beta blocker : decrease HR, contractility, systemic BP

pts receiving therapy prior to surgery continue to perioperative period

labetelol : reflex tachycardia is limited

osmolal : if asthma is present

-- prophylactic nitrates: controvetial

-- nifedipine : decrease BP in 5min, plateau in 30min

2. Congestive Heart Failure

Table 19.10

-- aggresive diuretics --> hypokalemia --> increase digitalis toxicity

--> dehyration --> hypotension during induction of anesthesia

-- MI,infection, pulmonary embolism, arrythmia

-- severe CHF place with Swan-Ganz cath helpful to guide perioperative fluid management

postoperative CHF results most frequently from excessive administration of iv fluids and blood

Treatment of pulmonary edema

--> iv furosemide, O2, iv morphine sulfate, elevation of head, iv aminophylline

3. Arryhthmia

with heart ds --> VT

without heart ds --> SVT

-- taking antiarrhthmic drugs prior to surgery should be continue

initiation of antiarrhymic medications is rarely indicated preoperatively

-- asymptomatic Morbitz I second-degree AV block : require no therapy

symptomatic Morbitz II, third degree AV block : permanent pacemaker before surgery

in emergency, pacing pulmonary artery cath

-- electrocautery units may interfere with demand type pacemaker

if demand type in place , pacemaker should be converted preoperativelu to the fixed-rate mode

-- surgery is not contraindicated in pts with budle branch block or hemiblock

4. Vavular heart disease

AS : great risk

sx : exertional dyspnea, angina, syncope

severe AS < 1cm2

significant AS : sinus rhythm be maintained during postoperative period

tachyarrythmia : digitalis

sinus tachycardia : propranolol

bradycardia below 45beats/min should be treated with atropine

SVT : verapamil

MS : mitral stenosis often have AF, if presents, digitalis should be used to reduce rapid ventrcular response

warfarin is withheld 1-3 days prior to surgery

anticoagulation is obtained by iv heparination, heparin is discontinued 6-8hrs prior to

surgery and resumed several days postoperatively

5. Hypertension

-- hypertension alone are no greater perioperative risk of cardiac morbidity or mortality

-- hypertension + heart ds : 13% perioperative mortality rate

diastolic BP >110mmHg, systolic BP>180mmHg should controlled prior to surgery

-- pts with beta blocker shouldbe maintained to prevent rebound tachycardia, hypercontractality, hypertension

-- Lab : ECG, chest X-ray, CBC, UA, E, Cr

-- hypertensive pts with sweating, palpitations, headache evaluated for coexisting pheochromocytoma