Avaliação do risco pré-cirúrgico

Princípios gerais e especiais do pré-operatório

Gerais:

• Preparar o paciente psicologicamente
  
• Fazer anamnese e Exame físico completos
  
  
• Solicitar exames laboratoriais e de imagem
  
  
• Tratar ou controlar doenças associadas
  
• Suspender o cigarro
  
• Orientar adequadamente o paciente e a família
  
• Ser rigoroso no preenchimento das fichas de consulta e do prontuário
  
• Prescrever a dieta adequada e o jejum
  
• Prescrever o controle de dados vitais
  
• Ter cuidado com a interação medicamentosa
  
• Prescrever ansiolítico
  
• Fazer lavagem intestinal em casos selecionados
  
• Preparar o colo em casos selecionados
  
• Recomendar o banho pré-operatório
  
• Realizar tricotomia só se absolutamente necessária
  
• Reservar sangue, serviços auxiliares e instrumentos
  
• Analisar todos os dados obtidos no pré-operatório, formar opinião e comunicar ao paciente
  

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A avaliação do risco deve ser realizada preferencialmente pelo clínico ou cardiologista do paciente, e idealmente devem conter nas seguintes situações:

• Radiografia de tórax: idade maior que 60 ou 65 anos; procedimento intratorácico; doença cardiovascular ou pulmonar; tabagistas; neoplasias.
  
• ECG: homens com mais de 40 anos e mulheres com mais de 50 anos de idade; fatores de risco para doença coronariana; obesidade; uso de digoxina.
  
• Urina rotina e urocultura: pacientes com sintomas de ITU, diabéticos, doentes renais crônicos, ou procedimentos com colocação de próteses.
  
• Hemograma com plaquetas: idade inferior a seis meses, mulheres de qualquer idade, homens acima dos 60 anos, procedimento com previsão de perda sanguínea intensa, doença cardiovascular, doença pulmonar, tabagismo, doença renal, doenças malignas, obesidade mórbida, uso de anticoagulantes.
  
• Nitrogênio uréico sanguíneo, creatinina e glicemia: acima de 60 anos, doença cardiovascular, renal, diabetes, uso de digoxina ou diurético, ou costicosteróides.
  
• Tempo de protrombina e tempo de tromboplastina parcial ativada (TP  e TTPa): história pessoal ou familiar de doença hemorrágica, doença hepática, uso de anticoagulantes.
  
• beta-hCG: todas as mulheres em idade fértil.
  

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O restante dos dados será colhido e analisado pelo cirurgião no pré-operatório.

Referência: Ernesto Lentz de Carvalho Monteiro; Euclides Matos Santana. Técnica Cirúrgica. 1ªedição. Ed. Guanabara-Koogan.


Preoperative medical evaluation of the healthy patient
Author
Gerald W Smetana, MD
Section Editor
Mark D Aronson, MD
Deputy Editor
Fenny H Lin, MD

INTRODUCTION — Clinicians are often asked to evaluate a patient prior to surgery. The medical consultant may be seeing the patient at the request of the surgeon, or may be the primary care clinician assessing the patient prior to consideration of a surgical referral. The goal of the evaluation of the healthy patient is to detect unrecognized disease and risk factors that may increase the risk of surgery above baseline and to propose strategies to reduce this risk.

The evaluation of healthy patients prior to surgery is reviewed here. Preoperative assessments for specific systems issues and surgical procedures are discussed separately.
CLINICAL EVALUATION — In general, the overall risk of surgery is extremely low in healthy individuals. Therefore, the ability to stratify risk by commonly performed evaluations is limited.

Screening questionnaire — Screening questions appear on many standard institutional preoperative evaluation forms. One validated screening instrument, derived from 100 patients, comprises 17 questions that allowed nurses to identify those patients who would benefit from a formal preoperative evaluation by an anesthesiologist (table 4) [8]. The questions chosen for this questionnaire were devised to detect pre-existing conditions shown to be associated with perioperative adverse events.

Age — A number of commonly employed and validated indices consider age as a minor component of preoperative coronary risk. (See "Estimation of cardiac risk prior to noncardiac surgery".)

Some studies found a small increased risk of surgery associated with advancing age [9,10]. In a review of 50,000 elderly patients, for example, the risk of mortality with elective surgery increased from 1.3 percent for those under 60 years of age, to 11.3 percent in the 80 to 89 year-old age group [10]. Among 1.2 million Medicare patients undergoing elective surgery, mortality risk increased linearly with age for most surgical procedures [11]. Operative mortality for patients 80 years and older was more than twice that of patients 65 to 69 years old. However, age was not a significant predictor of cardiac complications after multivariable analysis in the cohort of patients used to derive a revised cardiac risk index [12].

In addition to the minor influence of age on perioperative cardiac risk, there is more robust literature supporting age as an independent risk factor for postoperative pulmonary complications. Age was one of the most important patient-related predictors of pulmonary risk, even after adjusting for common age-related comorbidities, in a systematic review [13]. (See "Evaluation of preoperative pulmonary risk".)

In contrast, some studies have found little relation between age and mortality rates due to surgery. One study reported the outcomes of surgery in 795 patients over 90 years of age [14]. No patients were Class I as classified by the American Society of Anesthesiologists (ASA) classification (table 5); 80 percent were ASA Class III or greater. Despite higher perioperative mortality rates in the elderly, survival at two years was no different than the actuarial survival in matched patients not undergoing surgery [14]. A larger study of 4315 patients also found a higher perioperative complication and mortality rate in older individuals, but the mortality rate was low [15]. Among 31 patients age 100 years and older undergoing surgery requiring anesthesia, perioperative and one-year mortality rates were similar to matched peers from the general population [16].

Much of the risk associated with age is due to increasing numbers of comorbidities that confer excess risk. After adjusting for comorbidities more common with age, the impact of age on perioperative outcomes is modest. Thus, age should not be used as the sole criterion to guide preoperative testing or to withhold a surgical procedure [17].

Exercise capacity — All patients should be asked about their exercise capacity as part of the preoperative evaluation. Exercise capacity is an important determinant of overall perioperative risk; patients with virtually unlimited exercise tolerance generally have low risk.

The ability to walk two blocks on level ground or carry two bags of groceries up one flight of stairs without symptoms are simple questions that can give a rough assessment of patient risk [18]. These activities expend approximately 4 metabolic energy equivalents (METs) [19]. (See "Estimation of cardiac risk prior to noncardiac surgery", section on 'Functional capacity'.)

In general, healthy patients who can perform these activities as part of their daily routine have a low risk for major postoperative complications. This was illustrated in a study of 600 consecutive patients undergoing major surgery [20]. Investigators asked each patient to estimate the number of blocks that they could walk on level ground and the number of flights of stairs they could climb without symptoms. The authors defined poor exercise capacity as the inability to either walk four blocks or climb two flights of stairs. Patients reporting poor exercise capacity had twice as many serious postoperative complications as those who reported good exercise capacity (20 versus 10 percent, respectively). There was also a significant difference in cardiovascular complications (10 versus 5 percent), but not for total pulmonary complications (9 versus 6 percent).

The importance of functional capacity was confirmed objectively in another report of 847 patients undergoing elective abdominal surgery [21]. In this study, poor exercise capacity, confirmed by cardiopulmonary exercise testing, was a stronger predictor of all-cause mortality than any of the conventional cardiac risk factors of the Revised Cardiac Risk Index.

The American College of Cardiology/American Heart Association guideline on preoperative cardiac evaluation recommends no testing for patients with good exercise capacity (at least four METs) regardless of the intrinsic risk of the planned procedure [18].

Medication use — Clinicians should obtain a history of medication use for all patients before surgery and should specifically inquire about over-the-counter, complementary, and alternative medications. Aspirin, ibuprofen, and other nonsteroidal anti-inflammatory drugs are readily available and are associated with an increased risk of perioperative bleeding. Specific inquiry about use of complementary and alternative medications should also be part of the preoperative assessment. A detailed discussion of perioperative medication management is presented separately. (See "Perioperative medication management".)

Obesity — Contrary to popular belief, in noncardiac surgery, obesity is not a risk factor for most major adverse postoperative outcomes, with the exception of pulmonary embolism. None of the published and widely disseminated cardiac risk indices for non-cardiac surgery include obesity as a risk factor for postoperative cardiac complications.

However, in cardiac surgery, some studies have shown higher complication rates for obese patients, including increased hospital stay [22], wound infections [22,23], prolonged mechanical ventilation [23], and atrial arrhythmias [23,24].

Representative studies related to postoperative mortality in noncardiac surgery include:

In a matched case control study of 1962 patients undergoing noncardiac surgery, obesity was not associated with increased mortality (1.1 percent in obese patients versus 1.2 percent in controls) [25].
In a large, multi-institutional, prospective cohort of 118,707 patients undergoing nonbariatric general surgery, obesity was inversely associated with postoperative mortality (OR 0.85, 95% CI 0.75-0.99), a phenomenon termed the 'obesity paradox' [26]. The authors suggest that the obese state carries a low-grade, chronic inflammatory that may be 'primed' to mount an appropriate inflammatory and immune response to the stress of surgery, in addition to supplying more nutritional reserve.
Other studies relating to complications in noncardiac surgery found that obesity increases rates for wound infections, but has no effect on other postoperative complications [27-31].

Obesity is also not a risk factor for postoperative pulmonary conditions other than pulmonary embolism. In a review which found that the unadjusted relative risks for pulmonary complications due to obesity were 0.8 to 1.7, the incidence of pulmonary complications was 21 percent in both obese and non-obese patients [31]. In another systematic review, only one of eight eligible studies using multivariable analysis to adjust for confounders found that obesity was a predictor of postoperative pulmonary risk [13].

The one exception to the observation that obesity does not increase the risk of noncardiac surgery is venous thromboembolism. Obesity is a major risk factor for postoperative deep venous thrombosis and pulmonary embolism. (See "Prevention of venous thromboembolic disease in surgical patients".)

Obstructive sleep apnea — Obstructive sleep apnea (OSA) increases the risk for postoperative medical complications including hypoxemia, respiratory failure, unplanned reintubation, and ICU transfer [32]. Most patients with obstructive sleep apnea are undiagnosed. The prevalence of previously undetected obstructive sleep apnea is particularly high in patients preparing for bariatric surgery. Given the increased risks of perioperative morbidity and the potential for altered anesthetic management, it is reasonable to screen patients for OSA before surgery with one of several validated screening instruments. A detailed discussion of the perioperative risks and the role of screening for OSA is presented elsewhere. (See "Surgical risk and the preoperative evaluation and management of adults with obstructive sleep apnea".)

Alcohol misuse — Patients who misuse alcohol on a regular basis have an increased risk for postoperative complications [33].

In a study of 9176 male US veterans, a screening questionnaire for alcohol misuse administered at any time within one year before surgery accurately stratified risk of postoperative complications [34]. There was a continuous relationship between postoperative complications and risk scores using the Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) questionnaire (table 6). Surgical site infections, other infections, and cardiopulmonary complications each increased across the strata of risk groups based on alcohol use patterns. A similarly conducted trial of the AUDIT-C questionnaire before total joint arthroplasty revealed comparable results [35]. Patients with high AUDIT-C scores (9 to 12 of 12 possible points) within the year before surgery also have longer lengths of stay, more ICU days, and higher unplanned reoperation rates [36].

Most trials of alcohol cessation interventions have been conducted in the nonoperative setting; a small study in patients undergoing colorectal surgery reported a beneficial effect of alcohol screening on postoperative complications [37]. The optimal period of cessation is unknown but at least four weeks of abstinence are required to reverse selected physiologic abnormalities [33].

Screening for alcohol misuse before surgery will identify a subset of patients at increased risk for postoperative medical complications. While the benefit of directed alcohol cessation programs before surgery is not well established in the literature, there is little apparent risk to such a strategy. The preoperative period also serves as an opportunity to identify patients who misuse alcohol and are candidates for intervention as part of primary care follow-up after surgery. Pending further study, it is reasonable to screen all patients for alcohol misuse before elective major surgery.

Smoking — Current smoking is associated with postoperative morbidity and mortality [38]. Smoking cessation prior to surgery may prevent postoperative complications.

A meta-analysis of six randomized trials found that stopping smoking prior to surgery led to a lower risk of total postoperative complications (RR 0.59, 95% CI 0.41-0.85) [39]. The same meta-analysis also pooled data from 15 observational studies and found that smoking cessation led to decreased wound healing complications (RR 0.73, CI 0.61-0.87) and pulmonary complications (RR 0.81, CI 0.70-0.93). Longer periods of smoking cessation prior to surgery were associated with lower rates of postoperative complications. A separate contemporaneous systematic review found similar results [40].

Evaluating for tobacco use and offering strategies to quit smoking may reduce risk of postoperative wound and pulmonary complications. (See "Overview of smoking cessation management in adults" and "Smoking cessation counseling strategies in primary care".)

Personal or family history of anesthetic complications — Malignant hyperthermia is a rare complication of anesthetic administration that is inherited in an autosomal dominant fashion. Due to the morbidity and potential mortality associated with this condition, the preoperative history should include questioning about either a personal or family history of complications from anesthesia. (See "Susceptibility to malignant hyperthermia" and "Malignant hyperthermia: Clinical diagnosis and management of acute crisis".)

LABORATORY EVALUATION — Several review articles in perioperative consultation and most local institutional policies support a selective approach to preoperative testing [3,7,18,41-44]. A practice advisory from the American Society of Anesthesiologists and a safety guideline from the Association of Anaesthetists of Great Britain and Ireland recommend against routine preoperative laboratory testing in the absence of clinical indications [44,45].

Timing of laboratory testing — When laboratory tests are felt to be necessary, it is probably safe to use test results that were performed and were normal within the past four months, unless there has been an interim change in clinical status. The validity of this approach was illustrated in an observational study which investigated the usefulness of 7549 preoperative tests performed in 1109 patients undergoing elective surgery [41]. The tests were duplicates of those performed within the year prior to surgery in 47 percent of cases:

Of 3096 previous results that were normal (as defined by hospital reference range) and performed closest to the time of but before admission (median interval two months), only 13 (0.4 percent) values were outside a range considered acceptable for surgery. Most of these abnormalities were predictable from the patient's history, and most were not noted in the medical record.
In contrast, of 461 previous tests that were abnormal, 78 (17 percent) repeat values at admission were outside a range considered acceptable for surgery, suggesting that tests that have recently been abnormal should be repeated preoperatively.
Laboratory studies — While preoperative laboratory testing is not routinely indicated, selective testing is appropriate in specific circumstances, including patients with known underlying diseases or risk factors that would affect operative management or increase risk, and specific high risk surgical procedures [42]. Specific laboratory studies commonly ordered for preoperative evaluation include a complete blood count, electrolytes, renal function, blood glucose, liver function studies, hemostasis evaluation, and urinalysis. These tests are discussed below with indications for their use in specific populations and surgeries.

Complete blood count — Anemia is present in approximately 1 percent of asymptomatic patients; surgically significant anemia has an even lower prevalence [3]. However, anemia is common following major surgery and the preoperative hemoglobin level predicts postoperative mortality. As an example, a large observational study of older veterans (n = 310,311, age ≥65 years) found an increase in 30-day postoperative mortality for patients with mildly abnormal preoperative hematocrits undergoing major noncardiac surgery, even in the absence of significant blood loss [46]. Adjusted mortality increased by 1.6 percent (95% CI 1.1 to 2.2 percent) for every one percentage point increase or decrease from a normal hematocrit, defined as 39.0 to 53.9 percent.

The data cannot distinguish whether an abnormal hematocrit serves as a marker for coexistent disease that increases mortality risk, or whether the anemia itself increases physiologic stresses and therefore complication rates.  

The observation that outcomes do not differ for patients undergoing hip surgery who were randomly assigned to either liberal or restrictive transfusion policies suggests that anemia is a marker for risk, rather than the cause of morbidity [47]. It remains unclear if the increased risk due to anemia is modifiable by interventions aimed at correcting the hematocrit.

A baseline hemoglobin measurement is suggested for all patients 65 years of age or older who are undergoing major surgery, and for younger patients undergoing major surgery that is expected to result in significant blood loss. In contrast, hemoglobin measurement is not necessary for those undergoing minor surgery unless the history suggests anemia.

The frequency of significant unsuspected white blood cell or platelet abnormalities is low [3]. Unlike the hemoglobin concentration, however, there is little rationale to support baseline testing of either. Nevertheless, obtaining a complete blood count, including white count and platelet measurement, can be recommended if the cost is not substantially greater than the cost of a hemoglobin concentration alone. There may be some costs incurred due to follow-up of false positive results; however, with respect to platelet counts, these costs do not appear to be substantial [48].

Renal function — Mild to moderate renal impairment is usually asymptomatic; the prevalence of an elevated creatinine among asymptomatic patients with no history of renal disease is only 0.2 percent [3,49]. However, the prevalence increases with age. In one study, for example, the prevalence among unselected patients aged 46 to 60 was 9.8 percent [50].

In the revised cardiac risk index, a serum creatinine >2.0 mg/dL (177 µmol/L) was one of six independent factors that predicted postoperative cardiac complications [12]. Renal insufficiency is also an independent risk factor for postoperative pulmonary complications [13] and a major predictor of postoperative mortality [51]. Renal insufficiency necessitates dosage adjustment of some medications that may be used perioperatively (eg, muscle relaxants).

For these reasons, it is appropriate to obtain a serum creatinine concentration in patients over the age of 50 undergoing intermediate or high risk surgery, although there is no clear consensus on this point.  It should also be ordered when hypotension is likely, or when nephrotoxic medications will be used.

Electrolytes — The frequency of unexpected electrolyte abnormalities is low (0.6 percent in one report) [3]. In addition, the relationship between most of these derangements and operative morbidity is not clear. Furthermore, clinicians can predict most abnormalities based on history (for example, current use of a diuretic, angiotensin converting enzyme (ACE) inhibitor, or angiotensin receptor blocker (ARB), or known chronic kidney disease).

Thus, routine electrolyte determinations are NOT recommended unless the patient has a history that increases the likelihood of an abnormality.

Blood glucose — The frequency of glucose abnormalities increases with age; almost 25 percent of patients over age 60 had an abnormal value in one report [50]. Most controlled studies have not found a relationship between operative risk and diabetes [9,50], except in patients undergoing vascular surgery or coronary artery bypass grafting [52,53]. While the revised cardiac risk index identified diabetes as a risk factor for postoperative cardiac complications, only patients with insulin-treated diabetes were at risk [12]. There is no evidence that asymptomatic hyperglycemia, in a patient not previously known to have diabetes, increases surgical risk. The rate of asymptomatic hyperglycemia in unselected surgical patients is low; in one report the incidence was only 1.2 percent [54].

Unexpected abnormal blood glucose results do not often influence perioperative management. As an example, one study evaluated the benefit of routine laboratory testing in 1010 presumably healthy patients undergoing cholecystectomy [49]. Eight patients had unexpected elevations in preoperative serum glucose; only one of these patients developed significant postoperative hyperglycemia and this was not recognized until after total parenteral nutrition was started. No patient in this study benefited from routine preoperative measurement of serum glucose.

Thus, routine measurement of blood glucose is NOT recommended for preoperative healthy patients.

Liver function tests — Unexpected liver enzyme abnormalities are uncommon, occurring in only 0.3 percent of patients in one series [4]. In a pooled data analysis, only 0.1 percent of all routine preoperative liver function tests changed preoperative management (table 3) [7]. In a study of the National Surgical Quality Improvement Program database, among 25,149 patient with no comorbidities, the relative risk for major postoperative complications among patients who received preoperative liver function tests, when compared to those with no testing, approached one (RR 0.94, 95% CI 0.42-2.08) [6].

Severe liver function test abnormalities among patients with cirrhosis or acute liver disease are associated with increased surgical morbidity and mortality, but no data suggest that mild abnormalities among patients with no known liver disease have a similar impact [55]. Clinically-significant liver disease would most likely be suspected on the basis of the history and physical examination; thus, routine liver enzyme testing is NOT recommended.

Tests of hemostasis — Unexpected significant abnormalities of the prothrombin time (PT) or partial thromboplastin time (PTT) are uncommon [3,48]. Inherited coagulation defects are quite rare. For example, the incidence of hemophilia A and B among men is 1:5000 and 1:30000 respectively [56]. Nearly all of these cases would be evident based on clinical presentation prior to the preoperative medical evaluation. In addition, the relationship between an abnormal result and the risk of perioperative hemorrhage is not well defined, but appears to be quite low, particularly in those who are thought to have a low risk of hemorrhage on the basis of history and physical examination [57,58]. Even among neurosurgical patients, for whom a small amount of unanticipated bleeding could cause substantial morbidity, the medical history is the most useful screening test for bleeding diathesis. In a study of 11,804 patients undergoing spinal or intracranial surgery, a medical history that suggested risk for bleeding complications was substantially more sensitive that PT or PTT values in predicting need for transfusion, unplanned reoperation, and mortality [59].

In a pooled data analysis, an abnormal PT had a positive likelihood ratio of 0 for predicting a postoperative complication, and a negative likelihood ratio of 1.01 (table 3); in no case did the finding of an abnormal PT change patient management or modify the likelihood of a complication [7]. Similarly, the bleeding time is not useful in assessing the risk of perioperative hemorrhage [60,61].

Thus, routine preoperative tests of hemostasis are NOT recommended. We advise testing in patients with a known personal or family history of bleeding diathesis, or an illness associated with bleeding tendency [62].

The role of preoperative hemostasis evaluation in patients undergoing intermediate- to high-risk surgical procedures is somewhat controversial. We suggest NOT performing PT and PTT in such patients. This is consistent with the position of the British Committee for Standards in Haematology [62] and the American Society of Anesthesiologists [63]. Others, including authors for UpToDate, have suggested testing all patients undergoing intermediate to high risk surgical procedures, as clinicians may forget to ask about bleeding, or patient history may be unreliable. As discussed above, there is no evidence to support this practice. (See "Preoperative assessment of hemostasis".)

Urinalysis — The theoretical reason to obtain a preoperative urinalysis is detection of unsuspected renal disease and/or urinary tract infection. Asymptomatic renal disease can be detected by measurement of serum creatinine in selected patients. (See 'Renal function' above.)

Urinary tract infections have the potential to cause bacteremia and post-surgical wound infections, particularly with prosthetic surgery [64]. Patients with positive urinalysis and urine culture are generally treated with antibiotics and proceed with surgery without delay [65]. However, it is unclear whether a positive preoperative urinalysis and culture with subsequent antibiotic treatment prevent post-surgical infection. One study found no difference in wound infection between patients with normal and abnormal urinalysis [66]. Another study found that patients with asymptomatic urinary tract infection detected by urinalysis had an increased risk of wound infection post-operatively, despite treatment [67].

A cost-effectiveness analysis estimated that 4.58 wound infections in nonprosthetic knee operations may be prevented annually by the use of routine urinalysis, at a cost of $1,500,000 per wound infection prevented [68].

Thus, routine urinalysis is NOT recommended preoperatively for most surgical procedures.

Pregnancy testing — The knowledge that a woman is pregnant substantially changes perioperative management. The patient may elect to cancel elective surgery, or may decide in collaboration with her physicians to undertake a different, lower risk surgery than originally planned. In addition, anesthetic technique differs for pregnant women, and there may be risks to the fetus if a pregnancy goes undetected before surgery and anesthesia.

The National Patient Safety Agency in the United Kingdom recommends to always check whether a woman may be pregnant before surgery, and if pregnancy is possible after history taking, to offer a pregnancy test [69]. The American Society of Anesthesiologists recommends that clinicians offer pregnancy testing for women of childbearing age if the results would alter management [44]. While these guidelines provide some discretion in deciding which women to test, it is often not possible to reliably exclude pregnancy based on medical history taking alone [70]. Many institutions require pregnancy testing for all reproductive age women before surgery. There is low risk to this approach; false positives are rare, testing is inexpensive, and the results return rapidly. Thus, we suggest pregnancy testing in all reproductive age women prior to surgery. (See "Clinical manifestations and diagnosis of early pregnancy", section on 'Detection of hCG'.)

ELECTROCARDIOGRAM — Electrocardiograms (ECGs) have a low likelihood of changing perioperative management in the absence of known cardiac disease. Nevertheless, detecting a recent myocardial infarction is important since it is associated with high surgical morbidity and mortality [9]. (See "Estimation of cardiac risk prior to noncardiac surgery".)

The prevalence of abnormal ECGs increases with age [71]. Important ECG abnormalities in patients younger than 45 years with no known cardiac disease are very infrequent.  

The electrocardiogram alone may be a poor overall predictor of postoperative cardiac complications [72]. On the other hand, a preoperative ECG can be important as a baseline to compare with postoperative ECG abnormalities.

The 2007 American College of Cardiology/American Heart Association (ACC/AHA) Guidelines on Perioperative Cardiovascular Evaluation state that ECG is not useful in asymptomatic patients undergoing low risk procedures [18]. Similarly, the European Society of Cardiology 2009 preoperative guidelines do not recommend ECG in patients without risk factors [73].

The 2007 ACC/AHA guidelines do recommend a preoperative resting 12-lead ECG for selected patients as follows (table 7):

Patients with at least one clinical risk factor scheduled to undergo vascular surgery. These clinical risk factors are ischemic heart disease, compensated or prior heart failure, cerebrovascular disease, diabetes, and renal insufficiency.
Patients scheduled to undergo intermediate-risk surgery with known cardiovascular disease, peripheral artery disease, or cerebrovascular disease.
The ACC/AHA gave a less strong recommendation to perform an ECG for patients scheduled to undergo vascular surgery with no clinical risk factors (class IIa) OR those scheduled to undergo intermediate-risk surgery with at least one clinical risk factor (class IIb).

It is uncertain whether the preoperative approach to obese patients should differ from that of the general population in regard to ECGs. The AHA 2009 scientific advisory on cardiovascular evaluation and management of severely obese patients (BMI ≥40 kg/m2) undergoing surgery states that an ECG is reasonable in all obese patients with at least one risk factor for coronary heart disease (diabetes, smoking, hypertension, or hyperlipidemia) or poor exercise tolerance [74].

CHEST RADIOGRAPH — Preoperative chest x-rays add little to the clinical evaluation in identifying patients at risk for perioperative complications [43]. Abnormal findings on chest x-ray occur frequently, and are more prevalent in older patients. Several systematic reviews and independent advisory organizations in the US and Europe recommend against routine chest radiograph in healthy patients [75-78].

There is little evidence to support the use of a preoperative chest radiograph regardless of age unless there is known or suspected cardiopulmonary disease from the history or physical examination. In a meta-analysis of 21 studies of routine chest radiography, among a total of 14,390 routine chest x-rays, there were 1444 abnormal studies [79]. Only 140 abnormal findings were unexpected, and only 14 (0.1 percent) of all routine chest x-rays influenced management.

One study screened 905 surgical admissions for the presence of clinical factors that were thought to be risk factors for an abnormal preoperative chest x-ray [80]. The risk factors included age over 60 years, or clinical findings consistent with cardiac or pulmonary disease. No risk factors were evident in 368 patients; of these, only one (0.3 percent) had an abnormal chest x-ray, which did not affect the surgery. On the other hand, 504 patients had identifiable risk factors; of these, 114 (22 percent) had significant abnormalities on preoperative chest x-ray.

While routine preoperative chest x-rays are not indicated, we agree with the American College of Physicians (ACP) recommendation for chest x-rays in patients with cardiopulmonary disease and those older than 50 years of age who are undergoing abdominal aortic aneurysm surgery or upper abdominal/thoracic surgery [13]. Posteroanterior and lateral chest x-ray is also suggested by the American Heart Association for patients with severe obesity (BMI ≥40 kg/m2) [74]. In these patients, the chest radiograph may indicate undiagnosed heart failure, cardiac chamber enlargement, or abnormal pulmonary vascularity suggestive of pulmonary hypertension, warranting further cardiovascular investigation. The relationship between findings on chest x-ray and perioperative morbidity are not well defined in these populations, however, and studies are not available that indicate that preoperative radiography changes perioperative outcomes. Thus, we do not suggest routine chest x-rays in severely obese patients.

PULMONARY FUNCTION TESTS — Routine pulmonary function tests are NOT indicated for healthy patients prior to surgery. (See "Evaluation of preoperative pulmonary risk".)

These tests generally should be reserved for patients who have dyspnea that remains unexplained after careful clinical evaluation. Clinical findings are more predictive of the risk of postoperative pulmonary complication than are spirometric results [81]. These findings include decreased breath sounds, prolonged expiratory phase, rales, rhonchi, or wheezes.

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)

Basics topic (see "Patient information: Questions to ask if you are having surgery or a procedure (The Basics)")
SUMMARY AND RECOMMENDATIONS — The overall risk of surgery is low in healthy individuals. Preoperative tests usually lead to false-positive results, unnecessary costs, and a potential delay of surgery. Preoperative tests should not be performed unless there is a clear clinical indication.

A simple screening questionnaire can be helpful in the preoperative evaluation (table 4). Important potential risk factors to discuss with the patient include age, exercise capacity, alcohol, smoking, and medication use. Obesity is not a risk factor for most major adverse postoperative outcomes in patients undergoing noncardiac surgery. Clinicians should also inquire about personal or family history of complications from anesthesia and screen for symptoms of obstructive sleep apnea. (See 'Clinical evaluation' above.)
Routine preoperative laboratory tests have not been shown to improve patient outcomes among healthy patients undergoing surgery. In addition, routine testing in healthy patients has poor predictive value, leading to false-positive test results and/or increased medicolegal risk for not following up on abnormal test results. (See 'Rationale for selective testing' above.)
We suggest baseline hemoglobin measurement for all patients 65 years of age or older who are undergoing major surgery and for younger patients undergoing surgery that is expected to result in significant blood loss (Grade 2C). For other healthy patients, we suggest NOT performing routine hemoglobin, white blood count, or platelet measurements (Grade 2B). (See 'Complete blood count' above.)
In the revised cardiac risk index, a serum creatinine >2.0 mg/dL (177 micromol/L) predicted postoperative cardiac complications. We suggest NOT obtaining a serum creatinine concentration, except in the following patients (Grade 2B) (see 'Renal function' above):
Patients over the age of 50 undergoing intermediate or high risk surgery.
Younger patients suspected of having renal disease, when hypotension is likely during surgery, or when nephrotoxic medications will be used.
We suggest NOT testing for serum electrolytes, blood glucose, liver function, hemostasis, or urinalysis in the healthy preoperative patient (Grade 2B). We suggest pregnancy testing in all reproductive age women prior to surgery, rather than use of history-taking alone to determine pregnancy (Grade 2C). (See 'Laboratory studies' above.)
We suggest NOT ordering an ECG for asymptomatic patients undergoing low risk surgical procedures (Grade 2B). In accord with the 2007 American College of Cardiology/American Heart Association (ACC/AHA) guidelines, we suggest a 12-lead ECG in patients without perioperative clinical risk factor who require vascular surgical procedures (Grade 2C). In addition, a 12-lead ECG is part of the evaluation in patients with preexisting cardiovascular disease who are undergoing intermediate-risk surgery and in severely obese patients with poor effort tolerance or at least one additional cardiovascular risk factor. This is discussed in detail elsewhere. (See "Estimation of cardiac risk prior to noncardiac surgery", section on 'Resting electrocardiogram' and 'Electrocardiogram' above.)
We suggest that clinicians NOT order routine preoperative chest x-rays or pulmonary function tests in the healthy patient (Grade 2B). We suggest obtaining a preoperative chest x-ray in patients with cardiopulmonary disease and those older than 50 years of age who are undergoing abdominal aortic aneurysm surgery or upper abdominal/thoracic surgery (Grade 2C).

Referencias: uptodate.com