y r e g r u S Cardiac risk assessment The American College of Cardiology and the American Heart Associati on have published guidelines regarding cardiac risk assessment in noncardiac surgery in 199 6; these were updated in 2002. The European Society of Cardiology and the European Society of Anesthesiology have also published similar guidelines in 2010. Some of these guidelines have been summarized here. Preoperative risk strati \201 cation: 1. Low risk (<1% risk of myocardial infarction (MI) or death) 443 Type of procedures: Breast, endocrine, eye, genitourinary (GU) \200\224minor, gastrointesti nal(GI) \200\224minor, plastic/reconstructive, orthopedic-minor 2. Intermediate risk (1 \200\2235% risk of MI or death Types of procedures: GI-major, GU-major, vascular (carotid, endo- vascular, peripheral vasc ular angioplasty), head and neck, neurologic/ orthopedic-major, transplant (lung, renal, li ver) 3. High risk (>5% risk or MI or death) Types of procedures: Open abdominal aorta, peripheral vascular surgery Lee Index: Clinical factors predictive of cardiac complication following surgery: 1. Ischem ic heart disease 2. Heart failure 3. Stroke/transient ischemic attack 4. Diabetes requiring insulin therapy 5. Renal dysfunction/hemodialysis 6. High-risk surgery 1 point assigned to each clinical factor. For total points assigned, estimated incidence (% per 100 cases) of major cardiac complication is as follows: 0 point 0.4% 1 point 0.9% 2 points 7% 3 points 11% Noninvasive preoperative testing: Active, uncontrolled bleeding or high Aims at provid ing information on three cardiac risk markers: lv function, myo- cardial ischemia, and valv e abnormalities. Should occur if two of the three following factors are true in any patient : 1 Intermediate clinical predictors are present (Canadian class 1 or 2 angina, prior MI, c ompensated or prior heart failure, diabetes, renal insufficiency) 2 Poor functional capacity (<4 metabolic equivalent levels on Duke Activity Status Index AJC 1989) 3 High surgical risk procedure (emergency major operation, aortic or peripheral vascular di sease (PVD) surgery, prolonged surgery with large fluid shifts) Several studies have demonstrated that a left ventricular ejection fraction (LVEF) <35% is associated with an increased risk of a coronary event in patients undergoing noncardiac sur gery. Invasive perioperative evaluation: Recommended for the following patients prior to un dergoing surgery: 1 Patients with suspected or known coronary artery disease (CAD) who have demonstrated a high risk of adverse outcome based on noninvasive testing 2 Unstable angina or angina not responsive to medical therapy 3 Equivocal noninvasive test results in patients undergoing high-risk surgery 4 Urgent noncardiac surgery while convalescing from an acute mi 5 Perioperative MI 6 Candid ate for liver, lung, or renal transplant \211 40 yrs, as part of evaluation for transplan tation, unless noninvasive testing reveals high risk for adverse outcome 444 7 Patients should undergo preoperative coronary bypass grafting before high-risk surgery if their long-term outcome would be improved Other factors: 1 Prior to surgical intervention, severe hypertension (diastolic >110 mm Hg) should be controlled. 2 Symptomatic stenotic lesions (mitral or aortic) are associated with risk of perioperative severe heart failure and should be treated with intense medical therapy or surgical correc tion when possible. 3 Arrhythmias and conduction abnormalities: Management is identical to nonoperative setting ; however, pacemakers and implantable cardioverter defibrillator (ICDs) will need to be pro grammed off prior to surgery because of the concern of electrocautery use. 4 Medical therapy, particularly \222 -blockade, should be started days prior to planned su rgery and continued postoperatively with a dose titrated to achieve a resting heart rate ar ound 50 \200\22360 bpm. Patients who have a contraindication to \222 -blockade (chronic ob structive pulmonary disease [COPD]) may be started on -adrenergic agonists. y r e g r u S 5 Some studies indicate that maintenance of normothermia and adequate analgesia prevents cardiac events. 6 Because 95% of coronary events may be silent, postoperative ECG moni- toring should be performed in high-risk patients. All patients who smoke should be encouraged to discontinue smoking prior to surgery. Prophylactic antibiotics and bowel preparation The rate of wound infection following surger y ranges from <5% for clean cases without entry into the GI tract to >50% for intra-abdomin al perforation. Successful prevention has been demonstrated with the use of IV antibiotics only. Preoperative mechanical bowel preparation In the era of routine IV antibiotics, mecha nical bowel preparation prior to surgery has not shown to be beneficial in the prevention o f anastomotic complications or wound infections. However, most surgeons find it more esthet ically pleasing, and it facilitates bowel anastomosis and the identification of intralumina l lesions. The mechanical bowel preparations utilized, either polyethylene glycol 4 L or Mi raLax, do not cause significant electrolyte abnormalities and therefore are beneficial in p atients with cardiac disease or renal insufficiency, and in the elderly. Previously, sodium phosphate hypertonic solutions were utilized; however, dehydration and significant electro lyte abnormalities( \206\221 Na, \206\221 Phos, K, Ca) have led to the removal of these p reparations from the market. Preoperative oral antibiotics There has been much debate over the use of preoperative oral antibiotics, especially with the use of IV antibiotics. Curren tly, there are sufficient data to suggest that the use of preoperative oral antibiotics is beneficial in the prevention of surgical site infections, and their use is endorsed by many surgical societies. Preoperative iv antibiotics The surgical literature supports the routi ne use of IV antibiotics in the prevention of wound infections. To be effective, the dose s hould be given 1 h prior to incision. Meta-analysis has demonstrated that a single dose is all that is necessary, although frequently three doses are given. 1 First-generation cephal osporin is given in noncontaminated surgery with- out entry into the GI tract(e.g., Ancef 1 g q6h while in the operating room). 445 2 Second-generation cephalosporin is given in cases in which limited con- tamination is exp ected, including entry into the GI tract. This antibiotic covers aerobic and anaerobic bact eria (e.g., cefotetan 2 g q6h while in the operating room). 3 For penicillin-allergic patients, cephalosporins should be avoided as well (5% cross-reac tivity). Alternatives include clindamycin or vancomycin. 4 For intra-abdominal perforation, coverage with a third-generation cepha- losporin and metronidazole, a broad-spectrum penic illin, or fluoroqui- nolone is acceptable (e.g., cefuroxime 1.5 g and metronidazole 500 mg) . Venothromboembolic risk assessment and prevention Table 13.2 lists the current method of ri sk assessment for venous throm- boembolic disease. Table 13.2 Risk factors for venous thromboembolic disease Serious risk factors \212 \212 \212 \212 \212 \212 \212 \212 Other risk factors \212 \212 \212 \212 \212 \212 \212 \212 \212 \212 Age >60 Cancer undergoing treatment Previous DVT and pulmonary embolism (PE) Stroke with pa resis (>3 months) Trauma Heart and respiratory failure Prolonged procedure (>2 h) Inherited or acquired hypercoagulability Immobility Central venous catheterization Acute medical illness or sepsis Myeloproliferativ e disorder Inflammatory bowel disease Nephrotic syndrome Obesity (body mass index [BMI] >30 kg/m Smoking Estrogen use Varicose veins 2) Contraindications to prophylaxis for venous thromboembolic disease include \212 \212 \212 \212 \212 \212 \212 \212 \212 \212 Active, uncontrolled bleeding or high risk of bleeding Systemic anticoagulation Bacterial e ndocarditis or pericarditis Severe head trauma Malignant hypertension Threatened abortion S evere thrombocytopenia Heparin or enoxaparin: Heparin-induced-thrombocytopenia Enoxaparin: Spinal tap, epidural instrumentation Sequential compression device (SCD): Open wound or ext remity with DVT 446 Risk categories and management See Table 13.3. y r e g r u S Table 13.3 Risk categories \206\222 Prophylaxis Low risk \206\222 Early mobilization \212 \212 \212 Moderate risk \206\222 Heparin 5,0 00 U SC tid (first dose to be given 2 h prior to surgery) TEDS and SCDs \212 \212 \212 Minor/vascular/laparoscopic/urologic procedures <2 h Age <40 yrs NO additional risk factors Minor/laparoscopic/gynecological surgery Age <40 yrs With additional risk factors or \212 \212 \212 Minor surgery Age 40 \200\22360 yrs No additional risk factors or Major surgery Age <40 yrs NO additional risk factors \212 \212 \212 High risk \206\222 Heparin 5,000 U SC tid (first dose to be given 2 h pr ior to surgery) or enoxaparin 40 mg SC qd TEDS and SCDs \212 \212 \212 Any surgery Any age >60 yrs NO additional risk factors or \212 \212 \212 Very high risk \206\222 Heparin 5,000 U SQ tid (first dose to be given 2 h prior to surgery) or enoxaparin 40 mg SC qd and TEDs and SCDs \212 \212 Minor surgery Age 40 \200\22360 yrs With additional risk factors Major surgery Serious risk factors ( 2) or \212 \212 \212 Major surgery Age >60 yrs With any additional risk factor 447 Informed consent The purpose of the informed consent is to document that a discussion was u ndertaken between the surgeon and the patient with regards to the planned procedure. This d iscussion is paramount with regards to the patient \200\223physician relationship. During t his discussion, the physician should feel confident that the patient has a reasonable expec tation of what is going to be done at the time of surgery. The patient should be informed o f the known foreseeable complications. The patient should also be informed of the alternati ves to surgery. All questions should be answered. It is man- datory in many institutions th at one-sided surgeries be marked with the surgeon \200\231s initials and the agreement of t he patient prior to incision (i.e., nephrectomy). Perioperative IV fluid and electrolyte management The goal of fluid therapy is the normaliz ation of hemodynamic parameters and the body fluid electrolyte composition. Intraoperative fluids With the exception of major hemorrhage, avoid taking a patient to sur gery without adequate resuscitation. Anesthesia compounds shock by inhibit- ing normal baro receptor function, causing vasodilatation and depressing cardiac contractility. Most patien ts can tolerate a 500 mL blood loss; however, loss in excess of this may require transfusio n. For third-space losses as a result of tissue trauma, isotonic solution such as lactated Ringer \200\231s should be used for replacement. Colloids are expensive and provide no adde d benefit. Postoperative fluids A normal requirement is 2 \200\2233 L/24 h, which allows fo r urinary, fecal, and insensible loss. This maintenance therapy should be supplemented by r eplacement of the additional fluids needed to replace ongoing third-space losses. Monitorin g fluid status is best accomplished through close following of vital signs, urinary output, and central venous pressure (CVP) monitoring. Urine output: Should be maintained at a leve l >0.5 mL/kg/h. The first 24 h: Isotonic solutions (0.9% saline) should be given initially because of ongoing third-space losses. A standard postoperative regimen: (One of many; 2 L 5% dextrose with 0.45% saline/24 h. Add K + postop (20 mEq/L). More K + is needed if losses are from the gut (e.g., diarrhea, vomiting or high NG tube output, intestinal fistula, hig h-output stoma). More saline is appropriate for those at risk of hyponatremia: See Table 13 .4 . When to increase the above regimen \212Dehydration: This may be by 5 L if severe. Replace this slowly. \212 \212 \212 All causes, except for cardiogenic shock Shock: Operative losses: Losses from gut: 0.45% saline with 20 mEq/L potassium. Insensible losses: Pancreatitis; allowed for. Losses from surgical drains: losses. (the night after su rgery) is commonly due to inade- Low urine output quate infusion of fluids; however, the po ssibility of bleeding must always be considered. Check jugular venous pressure (JVP), opera tive drains, proper Foley function and insert if not present, and review for signs of cardi ac failure. The fractional excretion of urine sodium (Fe Na ) can be used to determine how well the kidneys are processing sodium. If(Fe Na ) <1%, prerenal; if (Fe Na ) >1% consider intrinsic renal disease(acute tubular necrosis [ATN]). Treatment for prerenal disorder is t o increase IV rate. For patients with cardiac disease or intrinsic renal failure, further w orkup of organ-specific disorder is warranted (echocardiogram or renal US). If evidence of bleeding, transfuse and check coagulation factors. If in doubt, a fluid challenge may be in dicated: 500 mL of 0.9% saline over 30 min or Check operation notes for extent of bleeding. Replace nasogastric tube (NGT) aspirate volum e with \212 \212 Feverish patients and burns 448 There are large pools of sequestered fluid that should be \212 Check fluid charts and replace significant \212 200 mL of colloid (Hespan or albumin) over 30 \200\22360 min, with monitor- ing of urine output. Then you may increase IV rate (e.g., to 1 L/h of 0.9% saline for 2 \200\2233 h). Fu rther monitoring with a CVP line or CVP Swan \200\223Ganz catheter may be necessary. y r e g r u S \212 Guidelines for success (p. 667) \212 Be simple. Chart losses and replace them. Know the urine output. Aim for 60 mL/h; 30 mL/h i s the minimum in adults (0.5 mL/kg/h). Measure plasma electrolytes if the patient is ill. R egular electrolytes are not needed in young people with good kidneys unless patient has ong oing losses (vomiting, diarrhea). Start oral fluids as soon as possible; the kidney is smar ter than the best doctor. \212 \212 What fluids to use Hemorrhagic/hypovolemic shock (p. 745): Insert two large IV cannulas (14 or 16 G) for fast fluid infusion. Start with crystalloid (e.g., 0.9% saline) or colloid un til blood is available. The advantage of crystalloids is that they are cheap, but they do n ot stay as long in the intravascular compartment as colloids because they equilibrate with the total extracellular volume (dex- trose is useless for resuscitation as it rapidly equil ibrates with the enormous intracellular volume). In practice, the best results are achieved by combining crystalloids and colloids. Aim to keep the hemoglobin >8 mg/dL, and urine flo wing at >30 mL/h. Monitor pulse and blood pressure (BP) often. Septicemic shock: Infuse iso tonic (0.9% saline) fluids to replace third-space losses. Consider hypertonic saline (3%). Heart or liver failure: Avoid sodium loads. Excessive vomiting, diarrhea: Use 0.9% saline a nd replace losses, including K + . (See chart.) Urine output| (oliguria): Aim for output of >30 mL/h in adults ( mL/kg/h). Anuria means a blocked catheter. Flush or replace cathete r. Oliguria is usu- ally due to inadequate replacement of lost fluid. Treat by increasing f luid input. Acute renal failure may follow shock, nephrotoxic drugs, transfusion, or trauma . \212 \212 \212 Review fluid chart and examine for signs of volume depletion. Urinary retention is also com mon, so examine for a palpable bladder. Establish normovolemia (a CVP line may help here; n ormal is 0 \200\2235 cm H relative to sternal angle); you may need 1 L/h IVI for 2 \200\223 3 h. Catheterize bladder (for accurate monitoring). 2 O \212 If intrinsic renal failure (see Fe Na , above) is suspected, refer to a nephrolo- gis t early. Electrolyte concentrations (meq/l) 449 Location Salivary Gastric Bile Pancreatic Duodenal Ileum Colon Na + 50 100 140 140 140 140 100 K + 20 10 5 5 5 5 70 Cl \200\223 40 140 100 75 80 70 15 HCO 3 \200\223 30 \200\223 60 100 \200\223 50 30 H + \200\223 100 \200\223 \200\223 \200\223 \200\223 \200\223 Rate (ML/d) Up to 1 L Up to 4 L Up to 1 L Up to 1 L Up to 2 L Up to 2 L \200\223 Electrolyte management in the surgical patient Tables 13.4, 13.5, 13.6, and 13.7 detail the management of electrolytes in the surgical patient. Table 13.4 Hypo- and hypernatremia Hyponatremia The most common cause is excess free fluid. Symptoms related to hyponatremia i nclude nausea, headaches, weakness, cogni- tion|, coma, death. Hyponatremia results from in fusion of 5% dextrose in H 2 O, thiazide diuretics, inappropriate antidiuretic hormone (ADH ) secretion. Treatment (p. 668): 0.9% saline IVI; check electrolytes every 2 h; aim to brin g Na + up to 130 mmol/L by 1 \200\2232 mmol/L per hour. Diuretics may be useful in acute hy ponatremia, or if the patient is symptomatic. Hypernatremia The most common cause is excess free water loss. Less common in surgical patients. Diabetes insipidus (depressed ADH secre tion) can result from head trauma. Symptoms occur when Na + exceeds 160 mEq/ML; symptoms in clude irritability, restlessness, fever, seizures. Treatment: Free water is administered to correct Na + at a rate of 0.7 mEq/L/h. Table 13.5 Hypo- and hyperkalemia Potassium is the major intracellular cation and is the major determinant of intracellular o smolality. Hypokalemia A result of total body depletion (diarrhea, hyperaldos- teronism) or intracellular redistribution (acute alkalosis, glucose and insulin administration, catecho lamine excess). Symptoms include muscle weakness, ileus, arrhythmias; ECG may demonstrate f lattened T waves, depressed ST segments, prolonged QT, U waves. Treatment: Replace K + at 1 0 mEq/h. A drop of 1 mEq/ML in the serum K + level represents a total body loss of 100 mEq . Correct acid \200\223base abnormalities. Hyperkalemia In the postop patient, usually the result of diminished renal function. Also seen in crush and reperfusion injuries after vasc ular surgery. Acute elevation in K + can result from depolarizing muscle relax- ants (e.g., succinylcholine) Treatment: ECG changes (peaked T waves) paresthesia, and weak- ness shoul d be treated with a rapid infusion of calcium gluconate, 1 ampule of sodium bicarbonate, an d 50 g glucose along with 10 U of regular insulin, which will temporize for 30 min. Need IC U monitor- ing. Definite treatment includes K + -wasting diuretics or K + \200\223Na + exc hange resin (Kayexalate) 40 g in 100 mL of sorbitol. Alternatively, hemodialysis should be performed. 450 y r e g r u S Table 13.6 Hypo- and hypercalcemia Hypocalcemia In the postop patient, hypocalcemia is usually secondary to inadvertent or pla nned total parathyroidectomy. After the resection of a parathyroid adenoma, hypocalcemia ma y be secondary to tempo- rary nonfunction of existing glands as a result of atrophy. Other causes include acute pancreatitis and pancreatic fistulas, vitamin D deficiency, renal fail ure. Symptoms occur with serum level <8 mg/dL and include muscle cramps, perioral tingling, paresthesia, laryngeal stridor, tetany, seizures, psychotic behavior. Check for hyperactiv e deep tendon reflexes: Chvostek sign and Trousseau sign. ECG changes include prolonged QT interval caused by prolongation of the ST segment. Treatment: Verify if not secondary to a low albumin (check ionized cal- cium). IV calcium gluconate or calcium chloride (can burn i n the IV). Should not be administered at a rate >50 mg/min (2.5 mEq/min). Oral replacement with calcium gluconate, citrate, or carbonate (TUMs), as well as vitamin D supplementation to increase GI absorption. Hypercalcemia Primary hyperparathyroidism as a result of a para- thyroid adenoma is the most common cause of hypercalcemia. Other causes include chief cell hyperplasia, renal failure, paraneoplastic syn- drome, familial hyperkalemia. Symptoms inc lude muscle fatigue, weak- ness, personality disorders, psychoses, coma, hypertension, shor tening of QT interval on ECG, nausea, vomiting, abdominal pain, nephrocalci- nosis, and lit hiasis ( \200\234bones, stones, and abdominal groans \200\235). Treatment: Serum Ca + >14 m g/dL must be dealed with immediately. Hydration with 0.9% or 0.45% saline with 20 mEq of K + intravenously at 200 \200\223300 mL/h to promote diuresis. Furosemide will enhance Ca + e xcretion. Long-term treatment requires resection of the parathyroid adenoma or the tumor. M etastatic bone disease resulting in hypercalce- mia may respond to mithramycin or calcitoni n. Metastatic breast disease or hematogenous disease may respond to steroids. ESRD patients on dialysis may respond to a low-calcium dialysate. Table 13.7 Hypo- and hypermagnesemia Hypomagnesemia Prolonged period of IV fluid without Mg 2+ replace- ment is the most common cause in the postoperative period. Symptoms are similar to hypocalcemia. Hypokalemia may de velop. Treatment: Large deficits are best managed by IV doses infusion with up to 4 g. For mild deficits, magnesium can be given orally. Hypermagnesemia Renal failure is the primary reason. Symptoms include depressed neuromuscular function. Treatment: Calcium antagonizes t he effects of magnesium, so a slow IV of 5 \200\22310 mEq of calcium is used in acute cases . 451 The control of pain The control of postoperative pain is essential and must be individualiz ed (Table 13.8). Numerous studies have indicated that patients recover more quickly and hav e less complications and a better experience if their pain is well controlled. Guidelines f or success Review and chart each pain carefully and individually. \212 \212 \212 \212 \212 Identify and treat the underlying pathology wherever possible. Give regular doses rather th an on an as-required basis. Choose the best route: Oral, PR, IM, epidural, SC, inhalation, or IV. Explanation and reassurance contribute greatly to analgesia. Allow the patient to be in charge. This promotes well-being and does not lead to overuse. Patient-controlled conti nuous parenteral morphine delivery systems are useful. Non-narcotic analgesia Acetaminophen: 650 mg/6 h PO. Caution in liver impairment. Recently, IV acetaminophen (1 g) was approved by the FDA for use in the United States for postoperat ive pain management. NSAIDs (e.g., ibuprofen 400 mg/8 h PO or Toradol 15 \200\22330 mg IV /6 \200\2238 h) are good for musculoskeletal pain and work well as an adjunct to the more p otent narcotics. Contraindications ( CI) : Peptic ulcer, clotting disorder, anticoagulants, renal insufficiency (Toradol). Cautions: Asthma, renal or hepatic impairment, pregnancy, a nd the elderly. Aspirin is contraindicated in children due to the risk of Reye \200\231s sy ndrome. Opioid drugs for severe pain Morphine (e.g., 2 \200\2234 mg/2 \200\2234 h IV push) or oxycodone (5 \200\22310 mg/4 h PO) or derivatives of these medications are best. Meperid ine (Demerol ) is also useful on a short-term basis. Long \200\223term use of meperidine c an result in central nervous system (CNS) hyperexcitability. These are controlled drugs. Si de effects of opioids: These include nausea, respiratory depression, con- stipation, cough suppression, urinary retention, BP \206\223 , and sedation (do not use in hepatic failure or head injury). Dependency is a problem, especially with longer acting drugs such as OxyCo ntin. Naloxone may be needed to reverse the effects of excess opioids (p. 790). Patient-con trolled analgesia Morphine or fentanyl is given through an IV pump, which is controlled by the patient. IV infusion allows the patient to receive the pain medication within 2 \200 \2235 min. The patient is allowed just so much medication every hour. Side effects are naus ea, pruritus, and ileus. Patient-controlled analgesia (PCA) is only effective if the patien t is properly educated on its use. Family members must be discouraged from administering th e drug for the patient. Epidural analgesia Opioids and anesthetics are given into the epidu ral space by infusion or as boluses. Ask the advice of the Pain Service (if available). Sid e effects (SE) : Thought to be more localized: Watch for respiratory depression; neuromuscu lar weakness, difficulty voiding, local anesthetic-induced autonomic blockade (BP \206\223 ). Adjuvant treatments for bone cancer pain; E.g., radiotherapy anticonvulsants, antidepre ssants, or steroids for nerve pain; antispasmodics (e.g., hyoscine [Buscopan ] 10 \200\223 20 mg/8 h) for intestinal, renal, or bladder colic. Transcutaneous electrical nerve stimula tion (TENS), local heat, local or regional anesthesia, and neurosurgical procedures (e.g., excision of neuroma) may be tried but can prove disappointing. Treat conditions that exacer bate pain (e.g., constipation, depression, anxiety). 452 y r e g r u S Table 13.8 Why is controlling postoperative pain so important? \212Psychological reasons : Pain control is a humanitarian undertaking. \212Social reason s : Pain relief makes surgery less feared by society. \212Biological reasons : There is ev idence for the following sequence: Pain \206\222 autonomic activation \206\222 \206\221 adrenergic activity \206\222 arteriolar vasoconstric- tion \206\222 reduced wound perfusi on \206\222 \206\223 tissue oxygenation \206\222 delayed wound healing \206\222 serious or mortal consequences. Deep vein thrombosis and swollen legs DVTs occur in 20% of surgical patients and many nons urgical patients. 65% of below-knee DVTs are asymptomatic; these rarely embolize to the lun g. Risks Age, pregnancy, synthetic estrogen, surgery (especially pelvic/ orthopedic), past DVT, malignancy, obesity, immobility, thrombophilia (p. 638). See Table 13.9. Signs Calf wa rmth/tenderness/swelling, mild fever, pitting edema. Differential diagnoses Cellulitis (may coexist); ruptured Baker \200\231s cyst (both may coexist). Tests D-dimer blood tests are sensitive but not specific for DVT. They are also elevated in infection, pregnancy, maligna ncy, and postop. A \200\223ve result, combined with a low pre-test clinical probability sc ore is sufficient to exclude (see below). DVT. If D-dimer is elevated or the patient has a high/intermediate pre-test clinical probability score, do compression US. If this is \200 \224ve, a repeat US may be performed at 1 wk to catch early but propagating DVTs. Venograph y is rarely necessary. Do thrombophilia tests if there are no pre-disposing factors, in rec urrent DVT, or if there is a family history of DVT. Prevention Stop oral contraceptive pill s (OCPs) 4 wks preop. Mobilize early. See above. Treatment Meta-analyzes have shown LMWH (e .g., enoxaparin 1.5 mg/ kg/24 h SC) to be superior to unfractionated heparin (dose guided b y aPTT [p. 574]), but extensive ileofemoral thrombi may still require unfractionated hepari n because such patients were excluded from the trials. Start warfarin simultaneously, stopp ing heparin when International Normalized Ratio (INR) is 2 \200\2233; treat for 3 months if postop (6 months if no cause is found; lifelong in recurrent DVT or thrombophilia). Inferi or vena cava filters may be used in active bleeding, or, when anticoagulants fail, to minim ize risk of pulmonary embolus. Preventing postphlebitic change: Thrombolytic therapy (to re duce damage to venous valves) and graduated compression stockings have both been tried, but neither has been conclusively shown to be beneficial. 453 Swollen legs Bilateral edema implies systemic disease with \206\221 venous pressure (right heart failure) or intravascular oncotic pressure (any cause of albumin decrease, so test t he urine for protein). It is dependant (distributed by gravity), which is why legs are affe cted early, but severe edema extends above the legs. The exception is the local increase in venous pressure occurring in IVC obstruc- tion: The swelling neither extends above the leg s nor redistributes. Causes: Right-heart failure (p. 128). Low albumin. Venous insufficienc y : Acute (e.g., prolonged sitting; see Table 13.10) or chronic, with hemosiderin-pigmented, itchy, eczemato us skin ulcers. Vasodilators (e.g., nifedipine). Pelvic mass. Pregnancy \200\224if BP \206\221 + proteinuria, diagnose pre-eclampsia: Find an obstetri- cian urgently. In all the above, both legs need not be affected to the same extent. Unilateral edema: Pain rednes s implies DVT or inflammation; e.g., cellulitis or insect bites (any blisters?). Bone or mu scle may be to blame; e.g., trauma (check sensation and pulses: A compartment syndrome with ischemic necrosis needs prompt fasciotomy), tumors, or necrotizing fasciitis. Table 13.9 Pre-test clinical probability scoring for DVT In patients with symptoms in both legs, the more symptomatic leg is used. Clinical feature Active cancer (treatment within last 6 months or Score 1 point palliative) Paralysis, paresis, or recent cast immobilization of leg 1 point Major surgery or recently bedridden for >3 d in last 4 wks 1 point Local tenderness along distribution of deep venous system 1 point 1 point Entire leg swollen 1 point Calf swelling >3 cm compared to asymptom atic leg (measured 10 cm below tibial tuberosity) Pitting edema (greater in the symptomatic leg) Col lateral superficial veins (nonvaricose) Alternative diagnosis as likely or more likely than that of 1 point 1 point 2 points DVT 3 or more points: High probability; 1 \200\2232 points: Intermediate probability; 0 or fewe r points: Low pre-test probability of DVT. Table 13.10 Air travel and DVT In 1954, Homans first reported an association between air travel and venous thromboembolism . Recently, the supposed risk of DVT and subsequent pulmonary emboli associated with air tr avel (the so-called \200\234economy-class syndrome \200\235) has been the subject of much public scru- tiny. Factors such as dehydration, immobilization, reduced oxygen ten- sion, a nd prolonged pressure on the popliteal veins resulting from long periods in confined aircra ft seats have all been suggested to be contribu- tory factors. Although the evidence linkin g air travel to an increased risk of DVT is still largely circumstantial, the following fac ts may help answer questions from your patients, family, and friends: \212 454 The risk of developing a DVT from a long-distance flight has been estimated at 0.1 \200\223 0.4/1,000 for the general population. There is an increased risk of pulmonary embolus assoc iated with long-distance air travel. Compression stockings may decrease the risk of DVT, al though they may also cause superficial thrombophlebitis. The role of prophylactic aspirin i s still under investigation. Measures to minimize risk of DVT include leg exercises, increa sed water intake, and refraining from alcohol or caffeine during the flight. \212 \212 \212 \212 Impaired mobility suggests trauma, arthritis, or a Baker \200\231s cyst. Nonpitting edema i s edema you cannot indent. Treatment Treat the cause. Giving diuretics to everyone is not a n answer. Ameliorate dependent edema by elevating the legs (ankles higher than hips; do not just use foot stools); raise the foot of the bed. Graduated support stockings may help ( C I : Ischemia). y r e g r u S Glucose management and the diabetic patient Hyperglycemia results from surgical trauma. Alt hough insulin levels are appropriately elevated, the tolerance of insulin-sensitive tissues is reduced. The importance of good glucose regulation (<130 mg/dL) in the postopera- tive period has led to a significant decrease in wound infection rates. Insulin-dependent diabet es mellitus (e.g., type 1 diabetes mellitus) \212 Patients are often well informed about their diabetes; involve them fully when managing the ir diabetic care. Stress or concurrent illness increases basal insulin needs. Always try to put the patient first on the list (surgery, endoscopy, bron- choscopy, etc.). Inform the s urgeon and anesthetist early. Stop all long \200\223acting insulin the night before. Get IV access before you need it urgently. If surgery is in the morning, stop all SC morning insu lin. If surgery is in the afternoon, have the usual short-acting insulin in the morning at breakfast. No medium- or long-acting insulin. Check blood glucose hourly. Aim for 100 mg/dL during surgery. Check electrolytes and glucose preop. Start an IV of 1 L of 5% dextrose wi th 20 mmol KCL/8 h. Dextrose saline can be given if Na + low, but do not give only saline; dextrose may need constant infusion to maintain blood glucose. Start an infusion pump with 50 U short-acting insulin in 50 mL 0.9% saline. Give according to sliding scale (below), ad justed in the light of blood glucose. Postop, continue IV insulin and dextrose until patien t is tolerating food. Finger-stick glucose every 2 h. Switch to usual SC regimen. \212 \212 \212 \212 \212 \212 \212 Practical hints \212 Some prefer to control blood sugar with a glucose-potassium-insulin (GKI) infusion. If the patient is having minor surgery and thus will definitely be able to eat postop, IV insulin may not be necessary. Some advocate giving the patient a small glucose drink early on the m orning of surgery and delaying his morning insulin dose and breakfast until after the proce dure. If in doubt, check with the anesthesiologist. \212 455 \212 Non-insulin-dependent diabetes mellitus (type 2 diabetes) \212 These patients are usually controlled on oral hypoglycemics (p. 290). If diabetes is poorly controlled, treat as for type 1 diabetes. Do not give long-acting sulfonylureas 24 h prior to surgery, as they can cause prolonged hypoglycemia on fasting. Beware of lactic acidosis in patients on biguanides (e.g., metformin). It is recommended to hold dose of metformin 2 4 h prior to surgery. If the patient can eat postoperatively, simply omit tablets on the mo rning of surgery and give postop with a meal. If the patient is having major surgery with r estrictions to eating postop, check fasting glucose on the morning of surgery and start IV or SC insulin given according to sliding scale. Postop, consult the diabetic \212 \212 \212 \212 team as the patient may need a phase of insulin to supplement his oral hypoglycemics. Diet-controlled diabetes is usually no problem although the patient may temporarily become insulin-dependent postop. Monitor finger-stick glucose before meals and bedtime. Avoid givi ng 5% dextrose IVI as a fluid replacement as blood glucose will rise. IV insulin sliding sc ale (This is only a guide; values are in mg/dL): Finger stick glucose (mg/dL) <60 60 \200\223130 131 \200\223180 181 \200\223250 251 \200 \223350 >351 IV soluble insulin Alternative SC insulin None (50% glucose IV) No insulin 1 U/h 2 U/h 3 U/h 6 U/h None (50% glucose IV) No insulin 2 U SC 4 U SC 6 U SC 8 U SC Blood transfusion and blood products Blood should only be given if strictly necessary, and a preoperative discus- sion regarding its use should be always undertaken. \212 Know right patient at the right time. Take blood for cross-matching from only one patient a t a time. Label immediately. This minimizes risk of wrong labeling of samples. When giving blood, monitor temperature and BP every h. and use local procedures to ensure that the right blood gets to the \212 \212 Type and screen requests Find your local guidelines for elective surgery. Obtaining c ross-matched blood is easier if the patient has already been typed and screened. No units a re set up for the patient when only a type and screen is requested. Furthermore, blood typi ng and screening may identify antibodies in a patient \200\231s blood that may require addi tional testing. Whole blood (rarely used) Indications: Exchange transfusion; grave exsangui nation: Use cross-matched blood if possible, but if not, use \200\234universal donor \200 \235 group O Rh -ve blood, changing to cross-matched blood as soon as possible. Blood >2 da ys old has no effective platelets. Red cells (packed to make hematocrit 70%) Use to correc t anemia or blood loss. 1 U \206\221 Hb by 1 \200\2231.5 g/dL. In anemia, transfuse until Hb 8 g/dL. Platelet transfusion (p. 632) not usually needed if not bleeding or count is >2 0 \227 10 9 /L. If surgery is planned, get advice if <60 \227 10 9 /L. Fresh frozen plasm a (ffp) Use to correct clotting defects; e.g., DIC (p. 625), warfarin overdosage, liver dis ease. It is expensive and carries all the risks of blood transfusion. Do not use as a simpl e volume expander. Human albumin solution (plasma protein fraction) is produced as 4.5% or 20% protein solution and is basically albumin to use for protein replacement. Both the solu tions have much the same Na + content, and 20% albumin can be used temporarily in the hypop roteinemic patient (e.g., liver disease; nephrotic) who is fluid overloaded without giving an excessive salt load. Others Cryoprecipitate (a source of fibrinogen); coagulation concen trates (self-injected in hemophilia); immunoglobulin (anti-D). 456 Complications of transfusion Management of acute reactions (see Table 13.11): \212 y r e g r u S Acute hemolytic reactions (e.g., ABO or Rhesus incom- Early (within 24 h): patibility), ana phylaxis, bacterial contamination, febrile reactions (e.g., from HLA antibodies), allergic reactions (e.g., itch, urticaria, mild fever), fluid overload, transfusion-related acute lu ng injury (TRALI) \200\224basically ARDS due to anti-leukocyte antibodies in donor plasma. Infections (e.g., viruses [hepatitis B/C, HIV], bac- Delayed (after 24 h): teria, protozoa, prions), iron overload (treatable with desferrioxamine), graft-versus-host disease, and po sttransfusion purpura , potentially lethal fall in platelet count 5 \200\2237 d post \200 \223transfusion requiring specialist treatment with IV immuno-globulin and platelet transfu sions. \212 Massive blood transfusion This is defined as replacement of an individual \200\231s entire blood volume (>10 U) within 24 h. Complications: Table 13.11 Transfusion reactions A rapid spike of temperature (>40 C) at the start indicates that the transfusion should be stopped (suggests intravascular hemolysis or bac- terial contamination). For a slowly risi ng temperature (<40 C), slow the IVI \200\224this is most frequently due to antibodies aga inst white cells. Acute transfusion Action reactions Acute hemolytic reaction (e.g., ABO incompatibility) Agitation, T \206\221 (rapid onset) , \206\223 BP, flushing, abdominal/chest pain, oozing venopuncture sites, DIC STOP transfusion. Check identity and name on unit; tell hematologist; send unit + CBC and e lectrolytes, PT, PTT, cultures and urine (hemoglobinuria) to lab. Keep IV line open with 0. 9% saline. Treat DIC. Anaphylaxis Bronchospasm, cyanosis, BP, soft-tissue swelling SLOW or STOP the transfusion. Maintain airway and give oxygen. Transfer to ICU and contact code team for intubation. Bacterial contamination T \206\221 (rapid onset), \206\223 BP, STOP the transfusion. Check identity against name on unit; tell hematolo- gist and send uni t +CBC, electrolytes, clotting, cultures, and urine to lab. Start broad-spectrum antibiotic s. and rigors TRALI (transfer related acute lung injury) Dyspnea, cough ; CXR STOP the transfusion. Give 100% O 2 . Treat as acute respiratory distress syndrome (ARDS, p . 174). Donor should be removed from donor panel. 457 \200\234white out \200\235 Nonhemolytic febrile SLOW or STOP the transfusion. Give an antipyretic (e.g., Tylenol 1 g). Monitor closely. If recurrent, use leukocyte-depleted blood or white blood cell (WBC) filter. transfusion reaction Shivering and fever usually 30 \200\22360 min after starting transfusi on Allergic reactions Urticaria and itch SLOW or STOP the transfusion; give