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