The patient’s complete return to full participation in life and the capacity to perform its requisite activities

 Avoidance of recurrence of the problem for which the individual’s surgery was indicated

 Reduced subsequent doctor- and hospital-based care and need for medication

 Lifelong health

Factors that place a patient at risk can contribute to perioperative cardiovascular and pulmonary dysfunction if preventive strategies fail (Box 30-2). Cardiovascular and pulmonary complications are the major cause of perioperative morbidity and mortality, particularly in patients undergoing thoracic or cardiovascular surgery.⁵ The physical therapist must establish the risk factors based on premorbid health assessment including age, smoking habits, nutrition, weight, regular physical activity and fitness, sleep, and stress, as well as cardiac dysfunction, lung dysfunction, musculoskeletal dysfunction, neuromuscular dysfunction, and endocrine dysfunction—in particular, type 2 diabetes mellitus.⁶

Physical therapy has a role in preparing patients for surgery some weeks in advance—a service that is not being fully exploited in health care. Maximizing a patient’s health will lead to fewer complications, will shorten hospital stay, and will hasten recovery and return to full participation in daily life. Interventions can include health education, including initiating or supporting smoking cessation. Smoking cessation or smoking reduction by at least 50% has been shown to improve the outcomes after hip and knee replacements.⁷ Comparable benefits could be expected for other types of surgery, particularly cardiovascular and thoracic procedures. Optimizing nutrition and prescribing an exercise program, even if modified because of the patient’s underlying condition, can augment oxygen transport. Thus, when oxygen transport is unavoidably compromised by anesthesia and surgery, the patient has greater reserve capacity.

People who are overweight and obese have direct, serious weight-related morbidity including hypertension, type 2 diabetes mellitus, lipid-related heart conditions, and sleep apnea. In addition, people who require joint replacement surgery because of arthropathy secondary to irreversible joint damage are more likely to be overweight.⁸ Thus, overweight and obesity constitute major complications during surgery and recovery. Given their prevalence, overweight and obesity warrant being addressed by physical therapists in every patient, whether surgical or medical (see Chapters 1 and 6). Furthermore, body mass index as well as weight-to-hip ratio and age have been reported to be significant predictors for type 2 diabetes mellitus and hypertension, which further complicates the clinical presentation and management of surgical patients who are overweight or obese.⁹

Early surgery for hip fracture in older adults has not been shown unequivocally to result in improved outcomes—that is, reduced complications (pneumonia and bed sores), earlier recovery, and reduced mortality.¹⁰ It is likely that clinically some patients may benefit whereas others may benefit from some delay. Irrespective, the outcomes of physical therapy will be enhanced in either situation if instituted in a timely manner. Studies are needed to establish the degree to which physical therapy including lifestyle behavior change (weight loss in particular) may avert surgery all together, or appropriately delay it. In some patients, early surgery may be preferable. In this case, some finite period of time in which a course of physical therapy could be instituted prior to surgery, could augment surgical outcomes.

Preoperative Assessment And Preparation For Surgery

To minimize risk, reduce perioperative morbidity and mortality, maximize healing, and shorten postoperative recovery, patients need to be in the best physical and medical condition before anesthesia and surgery. In the case of elective surgery, patients often can be prescribed aerobic training (prescribed to meet the individual’s needs and capacity), smoking cessation, and weight-control programs beforehand. A preparatory preoperative role for physical therapy warrants greater attention and is currently underused in terms of improving the perioperative course and achieving optimal, sustainable surgical outcomes.

Preoperative physical therapy management includes the preoperative assessment and education; the primary components are shown in Box 30-3. During this time the physical therapist has an opportunity to develop rapport with the patient. The assessment establishes the risk of complications and prolonged hospital stay and the type and extent of perioperative physical therapy required. Postoperative neurological syndromes are common. Ongoing assessment helps ensure that these are identified and addressed early.²² The assessment establishes what the postoperative priorities will be; however, these are modified based on the postoperative assessment. The surgical procedures are described and the effects of surgery and anesthesia and sedation on gas exchange are reviewed so that the patient understands the importance of being actively involved in physical therapy, both during and between treatments after surgery.

There are no strict guidelines about which patients should receive perioperative physical therapy. Rather, the need for physical therapy should be made on a case-by-case basis, with the degree of the physical therapist’s involvement determined on the basis of the patient’s need. Although nonthoracic surgeries are generally associated with few cardiovascular and pulmonary complications (e.g., surgery of the extremities or lower abdomen), patients with preexisting cardiovascular and pulmonary pathology, hematological or neuromuscular pathology, or musculoskeletal pathology of the chest wall are at greater risk even in these relatively low-risk types of surgeries. In addition, patients are at additional risk if they are older or younger, smoke, or are overweight or pregnant. Thus each surgical patient must be assessed individually to establish the degree of relative risk during surgery and the necessity of perioperative physical therapy. In this way perioperative complications can be anticipated and avoided or reduced, which is preferable to managing complications once they have developed. The cardiovascular and pulmonary assessment is particularly important in the older individual, and early mobilization is critical postoperatively.

Even though a patient may have had minimally invasive surgery and an uneventful perioperative course, the physical therapist still may have a critical role in helping to achieve long-term surgical outcomes. Recurrence is possible, particularly if surgery was related to lifestyle factors. The physical therapist can take maximal advantage of contact with the patient and be actively involved in developing a program of sustained, lifelong health.

The importance of a thorough preoperative assessment and teaching by the physical therapist cannot be overstated. The components of preoperative assessment and teaching are summarized in Box 30-3. In cases of elective surgery, preoperative teaching includes a general description of the surgery to be performed, the effect of anesthesia and surgery on cardiovascular and pulmonary function, and the systemic effects of restricted mobility and recumbency. The lines, leads, and catheters usually associated with the surgery are explained. The patient is instructed in breathing control maneuvers, supported coughing, chest wall mobility exercises, mobility exercises for the limbs (e.g., hip and knee and foot and ankle exercises), turning in bed, sitting up, transferring, chair sitting, and walking erect postoperatively. In addition, the patient is taught methods of maximizing comfort with body positioning and supporting the surgical incision. If the bed has controls the patient can manipulate, he or she is taught how to make bed adjustments as required. The postoperative course is explained in general terms so the patient can anticipate this period. If the patient is well informed preoperatively, he or she will be better oriented and capable of cooperating when he or she wakes from the anesthesia.

Preoperative teaching is a central component of physical therapy management of the surgical patient. Such teaching establishes rapport with the physical therapist, who informs the patient about what to expect before and after surgery. In addition to reviewing the surgical procedures, the physical therapist reviews, and has the patient perform, deep breathing and supported coughing maneuvers, relaxation, bed mobility, positioning, transfers, and mobilization. Preoperative teaching reduces the patient’s anxiety and encourages the patient to be as active as possible in his or her recovery. Preoperative teaching reduces postoperative complications and the length of the hospital stay. High-risk patients benefit from preoperative teaching, and their cooperation is more easily solicited after the surgery. Understanding the patient’s perception of his or her condition, the surgery, expectations, and self-efficacy are also central to postoperative recovery.

The physical therapist may be consulted by the surgeon to help make a poor-risk patient into a better-risk patient. Patients with upper–respiratory tract infections before surgery may have their surgeries postponed, depending on the type and extent of surgery to be performed, level of anesthesia indicated, and other medical conditions including cardiovascular and pulmonary disease, age, and smoking history. Patients with preoperative lower–respiratory tract infections constitute a greater operative risk; hence these patients often have their surgeries postponed until the infection has resolved. Patients with chronic cardiovascular and pulmonary diseases require a prolonged period of preoperative physical therapy in preparation for surgery. Elective surgery is not usually considered during an exacerbation of chronic lung disease. Even minor surgery may be potentially hazardous for the patient with previous lung disease. The adverse effects of total anesthesia on these patients are magnified because of their reduced pulmonary reserve capacity. Smoking should be discontinued for as long as possible before surgery. The patient is placed on an exercise conditioning program, a regimen of bronchial hygiene, oxygen if necessary, and prophylactic antibiotics. Even patients with extremely low functional work capacity can enhance the efficiency of the steps in the oxygen transport pathway (see Chapters 18 and 19) with a modified aerobic exercise conditioning program. This preoperative preparation may take one to several weeks, depending on the patient and the indications for surgery. Patients who are overweight can reduce their risk of perioperative complications by losing weight. Body mass is a major determinant of lung function, respiratory mechanics, and oxygenation during anesthesia,²³ and adverse effects on these can lead to major surgical complications and problems during recovery.

Preoperative inspiratory muscle training has gained renewed interest as a means of preserving respiratory muscle function postoperatively and reducing postoperative pulmonary complications. Although maximal inspiratory pressure can be preserved,24,25 studies are needed to show that this intervention augments outcomes over and above the benefits of an exercise program before surgery. Furthermore, a narrowly focused intervention such as inspiratory muscle training may overlook the benefits of a more holistic preoperative preparation program. Such training needs to be prescribed judiciously.

The goals of postoperative physical therapy management related to oxygen transport appear in Box 30-4. The patient is mobilized in a systematic sequence that progresses from supine to turning in bed to sitting over the bed to standing to sitting in a chair to walking (Table 30-1). Some patients progress through these steps quickly, whereas others take longer. The rate at which patients are progressed depends on their responses. Pain medications are coordinated as needed with treatments to maximize treatment effectiveness. This progressive sequence is comparable to that of phase I of cardiac rehabilitation, the inpatient phase for surgical as well as medical patients, and includes education, counseling, and treatment as indicated. These goals are addressed between as well as during treatments. The patient is instructed in mobilization and body positioning coordinated with deep breathing and supported coughing maneuvers between treatment sessions, and these interventions should be performed hourly during waking hours.^26,27 Such a regimen has been reported to result in favorable outcomes for invasive abdominal surgery.²⁸

In addition to the primary treatment goals related to oxygen transport, other postoperative goals include the following:

These goals are achieved with the prescription of mobilization and its constituent mobility exercises including hip and knee flexion and extension exercises and foot and ankle exercises. These exercises are performed hourly regardless of whether the patient is sitting in the chair or resting in bed.

Finally, there are important preventive goals (e.g., minimizing the effects of restricted mobility and recumbency on all organ systems) (see Chapters 19 and 20). Of particular concern in the surgical patient is the risk of thromboemboli and pulmonary emboli and the risk of pressure points and skin breakdown. Thus mobilization and regular activation of the muscle pumps to minimize circulatory stasis and frequent body-position changes are essential to reduce risks, which can have serious consequences for the patient’s recovery. Compression stockings are often put on the patient after surgery. These are not removed, except for cleaning and redistributing pressure, until the patient is consistently up and about. These stockings facilitate venous return and increase blood flow and velocity, thereby minimizing the risk of thrombus formation. Should thrombus formation be suspected, it may be necessary to attach an intermittent compression device to the legs to simulate muscle pump action.

With the exception of patients undergoing thoracic or cardiovascular surgery, patients are usually extubated before leaving the operating room or recovery area. Provided no complications develop, most other patients do not require an airway. Patients undergoing major thoracic surgery or cardiovascular surgery remain intubated and mechanically ventilated from several hours to 24 hours after surgery to minimize the work of breathing and hence the work of the heart required to meet the metabolic demands of respiration. These patients are informed that artificial airway and mechanical ventilation enables them to breathe more efficiently initially. A patient is also informed that he or she will not be able to speak while the airway is in place and may have a sore throat after its removal.

Patients are usually aroused and repositioned before leaving the operating room, although this is seldom remembered by patients. Not recalling the immediate postoperative course is common. Patients are likely to be receiving some form of pharmacological analgesia (e.g., morphine). If blood was required intraoperatively, whole blood, packed cells, or plasma may still be infused in the immediate postoperative period or for a longer period of time. Saline or other solutions are also infused for regulation of fluid balance until the patient is able to drink and eat normally. Once vital signs have stabilized, wounds are stable and not draining, and the patient is reasonably alert, he or she is transferred to the ward. The patient is retained in the recovery area should further monitoring be required. If complications develop and oxygen transport and gas exchange are threatened, the patient may be transferred to the intensive care unit.

The physical therapist may be consulted to assess and treat the patient as soon as he or she leaves the operating room or while in the recovery room. Most frequently the physical therapist sees the patient once he or she has been transferred to the ward and has been settled. The first 24 hours are critical.

The risk of cardiovascular and pulmonary complications is greatest during the perioperative period and diminishes as the patient becomes increasingly upright and mobile. Atelectasis and aspiration after extubation are major risks for the patient who has been intubated. The goal immediately after extubation is to promote optimal alveolar ventilation, maximize lung volumes and capacities (especially FRC), minimize closing volumes, and maximize expiratory flow rates and hence cough effectiveness. Areas most susceptible to atelectasis are those that may have been physically compressed during surgery (e.g., the left lower lobe of the cardiovascular surgical patient and areas adjacent to a lobectomy or segmentectomy area).

Surgery constitutes a major insult to the body. After the trauma of surgery, anesthesia, sedation, fluid loss, incisions, and the increased energy requirements for healing and repair, patients can be expected to be lethargic and challenging to arouse. The relaxed state induced by anesthesia, sedation, and narcotics increases the risk of aspiration. This risk is exacerbated further in some patients by nausea and vomiting associated with anesthesia and narcotics. Moving and positioning the patient upright whenever possible and interacting with the patient stimulate the reticular activating system, making the patient more responsive and aroused. The increased metabolic demands that this requires, along with increased catecholamine release, helps overcome the residual effects of anesthesia, sedation, and muscle relaxants and their threat to oxygen transport, provided the demands are not beyond the capacity of the oxygen transport system to deliver oxygen.

Alternatively, some patients are restless and agitated after the effects of anesthesia have worn off. Hypoxemia can lead to restlessness and agitation. Thus it is important that these patients not be inappropriately sedated. This compounds their need for treatment while making them less able to cooperate with treatment simultaneously.29,30

At the outset of any treatment the patient needs to be aroused as much as possible to cooperate fully and derive the maximum benefit from treatment. The physical therapist interacts continuously with the patient to arouse him or her fully, maintain arousal, stimulate normal cognitive function and orientation, and elicit feedback from the patient to assess his or her response to treatment. Narcotics depress respiratory status and arousal, and these effects are accentuated in patients whose metabolic states have been disrupted with illness and in older persons. Thus the physical therapist must be vigilant in detecting untoward residual effects of narcotics in the surgical patient. Balancing sedation and analgesia with the needs of having the patient arousable and alert warrants good communication among the team members.

The role of perioperative physical therapy has been debated. Some argue that the nursing staff can assume responsibility for the prevention of postoperative complications, particularly in patients who have undergone minimally invasive and short surgeries. The assessment and goals of the physical therapist, however, are unique and are not duplicated by the medical or nursing staff or respiratory therapist.

Physical therapists identify threats to oxygen transport as well as its limitations and prevent and remediate these by prescribing and exploiting noninvasive interventions. Furthermore, the physical therapist considers multiple factors that threaten the long-term health and function of the patient after discharge. The physical therapist has a primary commitment to returning the patient to full participation in the community and prolonged, sustained health. A decision to institute physical therapy for a given patient is not based on the type of surgery alone. Rather it is determined through a systemic assessment of age, weight, fitness, smoking status, comorbidities, anxiety and stress, and external factors related to the patient’s potential response to anesthesia and surgery.

To sustain alveolar inflation and normal FRC postoperatively, mobilization and body positioning coordinated with breathing control and supported coughing must be carried out frequently (i.e., every 1 to 2 hours) to maintain optimal alveolar volume and distribution of ventilation. Maximal inspiratory maneuvers are coordinated with mobilization and body positioning at least every hour as tolerated. Maximal inspiratory maneuvers alone, however, are unlikely to be effective because the inspiratory pressure may be insufficient to inflate atelectatic alveoli. Rather, patent alveoli will tend to be overexpanded. Mobilization and body positioning will directly alter the intrapleural pressure gradient and thereby optimize alveolar expansion. In patients who are obese and anesthetized and paralyzed, the prone position increases FRC, lung compliance, and oxygenation.23,31 Being prone may have some postoperative role in some patients who are obese, but the hazards of recumbent positions must be weighed against the benefits of being upright.

Normal passive expiratory efforts to end tidal volume are encouraged, and maximal or forced expiratory efforts are usually avoided to prevent airway closure and potential increase of atelectasis. Huffing (glottis open) rather than coughing (glottis closed) also minimizes airway closure. With huffing there is less risk of bronchospasm than with coughing, in which the glottis is closed, transpulmonary pressure is increased, and a compressive phase is involved. If indicated, coughing maneuvers are most effective in the sitting or slightly leaned-forward position, in which lung volumes and forced expiratory flow are maximized and the respiratory muscles are at a mechanical advantage with respect to the length-tension characteristics of the muscle fibers. Airway closure is position-dependent (see Chapter 20); therefore the degree of expiration encouraged by the physical therapist should be based on the patient’s body position. Airway closure is potentiated in patients who are older, smoke, or are obese and in patients who are in horizontal as opposed to upright body positions.

Mobilization and body positioning coordinated with breathing control and supported coughing maneuvers offer the greatest benefit to oxygen transport in the postoperative patient. Specific benefits are described in Chapters 18, 19 and 20. They include maximizing FRC, reducing closing volume, maximizing expiratory flow rates, promoting mucociliary transport, promoting airway clearance, optimizing lymphatic drainage, minimizing the effects of increased thoracic blood volume, maintaining fluid-volume regulating mechanisms, and minimizing the work of breathing and of the heart. Sustained maximal inspiration is one intervention that promotes alveolar expansion. Each deep breath is performed to maximal inspiration (i.e., to total lung capacity) with a 3- to 5-second breath hold. This maneuver may reduce pulmonary complications by promoting alveolar inflation and gas exchange. The patient is encouraged to repeat this maneuver several times hourly; frequently during mobilization; and before, during, and after body-position changes.

Although the benefits of incentive spirometry (Figure 30-1) postoperatively are equivocal at least after thoracic surgery,³² it may be useful in patients who are resistant or unable to cooperate fully with maximal inspiratory efforts or be adequately mobilized. Postoperative hypoxemia may be reduced with this technique, which uses the principle of sustained inspiration using a feedback device (either flow or volume feedback) to achieve maximal inflating pressure in the alveoli and maximal inhaled volume. Spirometers with a volume-controlled device, however, may improve diaphragmatic excursion more than flow-dependent devices.³³ With proper instruction, the incentive spirometer can be used independently by the patient, which can be an advantage. This technique ensures that each inspiration is physiologically optimal and is reproduced precisely from one inspiration to the next. Patients who are surgical risks may benefit from being taught how to use the incentive spirometer preoperatively by the physical therapist in order to promote better inflation of the lungs with incentive spirometry postoperatively. However, use of a spirometer does not replace being upright and moving as much as possible. The patient continues with a regimen of breathing control and coughing maneuvers in conjunction with being upright and moving until full mobility and activities of daily living are resumed.

The application of intermittent positive pressure breathing (IPPB) appears to be less effective for the postoperative patient than previously believed. The details of this modality are described in Chapter 43.

Exercise testing echocardiography performed early after coronary bypass surgery can identify individuals who are high risk and would benefit from intensive secondary prevention as a particular focus in a cardiac rehabilitation program.³⁴ Early exercise training improves autonomic nervous system function in addition to aerobic and functional capacity.³⁵

Thoracic surgery refers to surgery that necessitates opening the chest wall. By convention this term excludes specialized cardiovascular surgery (i.e., surgery of the heart and great vessels). Thoracic surgery is commonly performed for lung resections secondary to cancer (e.g., pneumonectomy, lobectomy, segmentectomy, and wedge resection). In addition, thoracic surgery is performed to remove an irreversibly damaged area of lung tissue secondary to bronchiectasis, benign tumors, fungal infections, and tuberculosis.

The most common incisions are posterolateral thoracotomy and median sternotomy. The posterolateral thoracotomy procedure requires the patient to assume the side-lying position with the involved side uppermost for the duration of the surgery. The uppermost arm is fully flexed anteriorly. The incision is made through an intercostal space, corresponding to the location of the lesion to be excised. The muscles incised include the latissimus dorsi, serratus anterior, external and internal intercostals laterally, and trapezius and rhomboid posteriorly.

At the conclusion of the surgery, chest tubes are placed to evacuate air and fluid from the pleural space by means of an underwater chest tube drainage system. The chest tube and drainage system resolve the pneumothorax created by reestablishing negative pressure in the pleural space and help to reinflate the remaining atelectatic lung tissue. After thoracic surgery, two chest tubes are usually inserted, one at the apex of the lung to evacuate air and one at the base of the lung to drain serosanguineous fluid. The therapist should become familiar with the various drainage systems, how drainage can be facilitated with mobilization and body positioning coordinated with breathing control and supported coughing maneuvers, and certain precautions that must be observed to avoid impairing drainage or disconnecting the tubing. Physical therapy for patients undergoing thoracic surgery has been reported to be cost-effective when a primary component of an interprofessional patient care management strategy⁴⁴ as well as when administered prophylactically.⁴⁵

Provided the chest tubes are not kinked, there is no contraindication to lying on the side of the chest tubes. Lying on this side, which is usually the side of the surgery and incision, is typically avoided by the patient. Consistent with the adage down with the good lung, a patient prefers to lie on the nonsurgical side. Prolonged periods in any position, however, particularly lying on the unaffected side, places these lung fields at risk. To minimize the risk of positional complications and hypoxemia, the patient is encouraged to turn to both sides. The specific positions and the duration of time spent within each, however, are based on a comprehensive assessment of the patient’s condition and the indications and contraindications for each body position.

Patients may appear to splint themselves, thereby restricting chest wall motion, to avoid pain when moving and deep breathing. They also may resist maximal inspiratory efforts when coughing. Although pain likely contributes to breathing at low lung volumes and ineffective coughing, phrenic nerve inhibition in patients with thoracic and upper abdominal surgeries is likely a more important factor restricting lung expansion. Being upright and moving is associated with increased FRC and tidal volume. Although modalities such as incentive spirometry may have a role in improving lung function in some high risk patients, generally it does not enhance recovery after thoracic surgery.³²

Postoperative complaints of pain are both musculoskeletal and pleural in origin. The large number of muscles incised, particularly in the posterolateral thoracotomy incision, combined with the operative position, contribute to the patient’s complaints of chest wall pain, shoulder soreness, and restricted movement. Deep breathing and coughing maneuvers may be associated with considerable discomfort after surgery. Pain is accentuated by apprehension and anxiety. Therefore treatments are coordinated with relaxation, noninvasive pain control modalities, and pain medication schedules to elicit the full cooperation of the patient.

Summary

Optimal surgical outcome is a team effort that extends beyond the technical success of the surgery. It is based on the return of the individual to full participation in life and long-term health, including no recurrence of the patient’s problem and reduced need for biomedical care and drugs in the short and long term; these also are primary physical therapy outcomes. This chapter reviews the principles of perioperative physical therapy management in individuals slated for surgery with a view to maximizing both short- and long-term outcomes. The physical therapy has a key role in risk factor identification and early intervention. Although risk is increased with more invasive and prolonged surgeries, this should not be assumed. Even minor surgery with an apparently uneventful immediate postoperative period can have an untoward outcome because of underlying risk factors. Indication for physical therapy is based on risk factors rather than condition or type of surgery. Given the prevalence of lifestyle-related conditions and their risk factors (e.g., ischemic heart disease, smoking-related conditions, hypertension and stroke, type 2 diabetes mellitus and obesity) that both necessitate elective surgeries and contribute to their complications and delayed recovery, physical therapists need to lead in developing preoperative preparation programs that include health education (initiating or supporting smoking cessation and optimal nutrition), weight reduction, and judiciously prescribed exercise programs.

Teamwork is the essence of successful surgical outcomes. The physical therapist is highly involved from assessment of the patient preoperatively with respect to anticipated necessity of treatment afterward based on a detailed assessment of perioperative risks, to treatment postoperatively, to, most important, postdischarge follow-up to ensure function is regained and the benefits of surgical and related management are sustained over the long term. Physical therapy intervention for the surgical patient is based on indications for that individual rather than the type of surgery.

The four categories of factors contributing to or threatening oxygen transport were described in Chapter 17 and are evaluated in the preoperative and postoperative assessments. These factors include pathology, restricted mobility and recumbency, extrinsic factors related to the patient’s care, and intrinsic factors related to the patient. This chapter examines in detail those factors related to surgery and anesthesia in particular, and the impact of underlying disease, restricted mobility, recumbency, and intrinsic factors on the effects of surgery and anesthesia. The role of the physical therapist, an integral member of the surgical team, is to ensure optimal long-term outcomes well beyond the technical success of the surgery, particularly in individuals who have undergone cardiovascular and thoracic surgery. A prime physical therapy outcome in patients who have undergone thoracic or cardiovascular surgery is prevention of both recurrence of the patient’s problem and repeated surgery.

Surgery and its physiological effects are described. Special reference is made to two specialized types of surgery that unfortunately have become all too common—namely, thoracic and cardiovascular surgery. These have the greatest impact on cardiovascular and pulmonary function.