Preoperative testing, as a component of the preanesthesia evaluation, may be indicated for various purposes, including but not limited to: discovery or identification of a disease or disorder that may affect the perioperative course, verification or assessment of an already known disease, disorder, medical or alternative therapy that may affect perioperative anesthetic care, and formulation of specific plans and alternatives for perioperative anesthetic care.

After obtaining the patient history, performing the physical examination and reviewing preoperative testing, the patient’s ASA status should be noted (Table 12.2). The ASA classification identifies patients according to the level of systemic illness.

A patient’s poor medical conditions and inappropriate selection for surgery when matching risk to procedure benefit, and inadequate preoperative preparation are factors associated with increased mortality in developing countries [9, 10].

In general, cardiac risk factors are determined by the patient’s condition prior to surgery, the prevalence of co-morbidities (as it relates to functional capacity), and the magnitude and duration of the planned surgical procedure. In rural environments a number of factors can contribute to an increased risk of cardiac complications during surgery. Examples include insufficient knowledge of the patient’s prior medical conditions (especially as it may relate to endemic disease), inadequate airway control, lack of appropriate monitoring equipment, undetected hypoxia, and lack of resuscitation drugs and colloids and other fluids [11–13].

A thorough assessment provides the clinician an opportunity to initiate medical therapy, coronary interventions, and specific surgical and anesthetic techniques tailored to each individual. Active or unstable cardiac conditions include unstable coronary artery disease, decompensated heart failure, significant arrhythmias, and severe valvular disease.

The Lee index is one of the most accurate indices for predicting cardiac risk in non-cardiac surgery [14]. It emphasizes the value of clinical data in perioperative risk stratification. The Lee index contains five independent clinical determinants of major perioperative cardiac events: a history of ischemic heart disease, a history of cerebrovascular disease, heart failure, insulin-dependent diabetes mellitus, and impaired renal function. High-risk type of surgery is the sixth factor. All factors are equally weighted with one point given to each.

The incidence of major cardiac complications is estimated at 0.4, 0.9, 7, and 11 % in patients with an index of 0, 1, 2, and 3 or more points, respectively (Table 12.3).

Cardiac complications after non-cardiac surgery depend not only on medical risk factors but also on the type of surgery being performed, the urgency, magnitude, type, and duration of the procedure, as well as changes in body core temperature, blood loss, and fluid shifts [15].

With regard to cardiac risk, surgical interventions can be divided into low-risk, intermediate-risk, and high-risk groups with estimated 30-day cardiac event rates (cardiac death and MI) less than 1 %, 1–5 %, and superior to 5 %, respectively (Table 12.4). Although only a rough estimation, this risk stratification provides a good indication of the need for cardiac evaluation, drug treatment, and assessment of risk for cardiac events [16]. Evaluation of functional capacity is considered to be another essential component in preoperative cardiac risk assessment [17, 18]. Functional capacity is measured in metabolic equivalents (METs). One MET equals the basal metabolic rate. Exercise testing provides an objective assessment of functional capacity. Without testing, functional capacity can be estimated by the ability to perform a number of activities of daily living (Table 12.5).

When functional capacity is high, the prognosis is excellent, even in the presence of stable ischemic heart disease or risk factors (>4 metabolic equivalents). On the other hand, when functional capacity is poor or unknown (<4 metabolic equivalents), consideration of other risk factors is required to determine the patient’s risk for perioperative morbidity.

Preoperative pulmonary care involves identifying patients at high risk for postoperative pulmonary complications and optimizing respiratory function for those with preexistent pulmonary disease [19, 20]. Postoperative pulmonary complications include atelectasis, bronchospasm, pneumonia, respiratory failure, and exacerbation of chronic lung disease.

Table 12.6 indicates conditions and risk factors that significantly increase the risk of such complications.

Smoking cessation before surgery should be initiated as soon as possible (at least 6–8 weeks prior to surgery, 4 weeks at a minimum) [21, 22].

The patient with preexisting renal disease poses a particular challenge to the safe delivery of anesthesia. Renal complications are more likely to occur in:

In non-cardiac surgery, the Kheterpal score is useful for the identification of patient at risk for postoperative renal impairment [28]. For patient without preexisting renal dysfunction seven identified preoperative predictors of acute renal failure include age, emergency surgery, liver disease, elevated body mass index, high-risk surgery, peripheral vascular occlusive disease, and chronic obstructive pulmonary disease necessitating chronic bronchodilator therapy. The score is applied as follows:

While a number of strategies have been suggested to minimize nephrotoxic insults, there is limited evidence to support the value of prophylactic and therapeutic interventions in patients at high risk for developing perioperative renal failure [29].

The Overseas Development Institute (ODI) currently puts the number of overweight and obese adults in developing countries at more than 900 million. Moreover, the number of overweight and obese adults has risen from 250 million to nearly a billion in the last 30 years [30]. The body mass index (BMI) is the most widely used classification. Patients are considered overweight with a BMI between 25 and 29.9 kg/m² and obese with a BMI between 30 and 49.9 kg/m². Patients with a BMI of 50 kg/m² or greater are considered superobese.

Obesity is accompanied by co-morbidities such as coronary artery disease, hypertension, OSAS and/or diabetes mellitus. Perioperative risk assessment should, therefore, focus on cardiac and pulmonary dysfunction as well as nutritional status [31].

Preoperative assessment of risk factors and clinical evaluation as well as ECG examination is essential in obese patients. To identify patients at risk for difficult airway, a neck circumferences of at least 43 cm as well as a high Mallampati score and male gender are predictors for difficult laryngoscopy and hence intubation [32]. Preoperative testing is indicated in obese patients in order to detect abnormal glucose/HbA1C levels and/or anemia [27].

Diabetes mellitus is a growing public health issue affecting people both in developing and developed countries [33]: approximately 150 million people have diabetes mellitus worldwide, and this number may very well double by 2025. Much of this increase will likely occur in developing countries. By 2025, while most people with diabetes in developed countries will be aged 65 years or more, in developing countries the age range is in the 45–64-year bracket during some of their most productive years.

Patients with diabetes are more likely to require surgery [34]. Elevated blood glucose in the perioperative period is a risk factor for surgical site infection [35] and diabetic patients are at greater risk for postoperative heart failure [36]. Both type I and II diabetic patients have a higher rate of difficult laryngoscopy than non-diabetic patients [37].

It is not necessary to test blood sugars routinely on all patients during the preoperative assessment. Screening for diabetes/risk of hyperglycemia can be based on history and examination or investigations of glycemic control. Risk factors include age, sex, family history of diabetes, low exercise level, and obesity [38, 27].

Anemia is an especially important public health concern in developing countries and is responsible for significant morbidity and mortality. About two billion people worldwide are estimated to suffer from anemia and it is reported to account for more than 700,000 deaths per year in Africa and Southeast Asia. The highest prevalence of anemia is in preschool-age children (47 %) although nonpregnant women constitute the largest group (468 million) [39]. Underlying causes for anemia are multi-factorial and largely preventable and include nutritional deficiencies, infections, multiple pregnancies, and hemoglobin disorders.

Low preoperative hemoglobin levels and a high level of surgical intervention can predict the need for intraoperative blood transfusion and potentially poor postoperative outcome. Low hemoglobin levels are associated with increased perioperative morbidity in surgical patients, longer recovery from procedures that involve blood loss, and a higher likelihood of postoperative infection. Depending on the hospital, and the lack of availability of routine blood tests, it may be beneficial to bring the equipment required to measure hematocrit (a small portable device), especially if procedures involving blood loss are anticipated. Given the risks and costs associated with allogeneic blood transfusion and the low availability of blood for transfusion, strategies have been developed for preoperative correction of anemia and prevention of perioperative blood transfusion needs as preoperative iron supplementation which may be considered to correct preoperative anemia [40].

In many developing countries, alcohol and cigarette use is rising rapidly and often at an earlier age. Intravenous drug use, involving heroin, amphetamine, and opiates, is on the rise [41].

Alcohol use disorders (AUDs) are associated with alcohol-related postoperative complications such as higher rates of wound infection, acute withdrawal and organ failure. For the preoperative detection of AUDs, the combined use of a standardized questionnaire (e.g., CAGE questionnaire) together with laboratory testing such as GGT (g-glutaryl transferase) and carbohydrate-deficient transferrin (CDT) is superior to either one alone [42, 43]. Alcohol abstinence for at least 1 month has been shown to reduce perioperative complications from 74 to 31 % [44].

According to the 2007 WHO/UNAIDS estimates, at the end of 2007, more than 95 % of HIV infections worldwide occur in developing countries with two-thirds occurring in sub-Saharan Africa where over 28 million people are living with HIV. Infection rates are lower in Asia and the Pacific, where over seven million are infected. However, since this syndrome is not specific, it is rarely recognized, even when clinically apparent.

Preoperative evaluation of the HIV-infected patient is similar to that of the general population; however, comorbidities, active substance use, and the presence of methicillin-resistant Staphylococcus aureus may be more prevalent in the HIV-infected population (see Table 12.7).