Prehabilitation for Thoracic Surgery

Michael Charlesworth, Richard Templeton

Abstract

The presurgical period is an ideal time for targeted interventions aimed at improving postoperative outcomes for all surgical patients. The aim is to restore physical and psychologic function following surgery. It is for all patients, and is not restricted to just those who are high or low risk. It can be defined as “a process on the cancer continuum of care that occurs between the time of cancer diagnosis and the beginning of acute treatment and includes physical and psychologic assessments that establish a baseline functional level, identify impairments, and provide interventions that promote physical and psychologic health to reduce the incidence and/or severity of future impairments.” That said, it presents many challenges. Specifically, for thoracic surgical patients awaiting resection of cancer, there is limited time available between diagnosis and surgery, and other related hospital appointments or treatments might place a burden on the patient, both physically and psychologically. Prehabilitation must be multimodal. It is the sum of marginal gains from several interventions, which are themselves complementary. It requires invested resources, infrastructure, organization, and an acceptance of the longer-term benefits for surgical outcomes, value for money, and public health. Herein, we describe various components which might comprise a multimodal thoracic surgical prehabilitation program.

Keywords

thoracic surgery; prehabilitation; exercise; smoking; nutrition

Introduction

Lung cancer accounts for 30% of all cancer cases, with outcomes for patients improving at a modest pace.¹ That said, 5-year survival for patients with stage IA to IIA cancer managed with a combination of chemotherapy and surgery exceeds 50%.¹ Lung cancer screening programs are increasingly used to identify patients at a stage where lung resection is possible.² Lung resection surgery is associated with a high incidence of postoperative pulmonary complications,³ which are themselves associated with reduced survival, increased morbidity, and a prolonged intensive care and hospital length of stay.⁴^,⁵ Enhanced recovery after surgery protocols and postoperative pulmonary rehabilitation are now engrained in perioperative pathways,^6–8 but preoperative rehabilitation, or prehabilitation, is a relatively new concept. The aim of thoracic prehabilitation is to reduce perioperative risk for patients who are suitable for surgery, or in some cases, move a patient who was previously unfit for surgery into a group which is suitable for surgery. For both these cohorts, the chance of survival may be increased.⁹ In this chapter, we discuss how that goal can be achieved using risk prediction, shared decision making, and a range of multimodal preoperative interventions that can be integrated into the preoperative pathway.

Risk Prediction

Patients presenting for thoracic surgery often have respiratory and/or cardiovascular comorbidities. The most widely used method for risk stratification are preoperative tests of pulmonary function.¹⁰ Respiratory mechanics are assessed by measuring the forced expiratory volume in one second (FEV₁), which can directly reflect the incidence of postoperative pulmonary complications. The ability of the lungs to undertake gaseous exchange is measured with the diffusing capacity for the lung for carbon monoxide (DLCO), which is associated with postoperative mortality. Finally, cardiopulmonary reserve can be evaluated using functional tests, such as shuttle walking or formal cardiopulmonary exercise testing.

Preoperative tests of pulmonary function help guide the extent of operative management. In patients with a value of more than 80% for FEV₁ and DLCO, resection might be undertaken up to a pneumonectomy. If either one is below 80%, exercise testing is required to measure the peak oxygen consumption (VO₂). If the peak or predicted postoperative VO₂ is less than 35% or less than 10 mL/kg/min, a lobectomy or pneumonectomy are not recommended.¹¹ For palliative procedures, such as lung volume reduction surgery or airway stenting, the decision to proceed is based on a risk versus benefit judgment on a case by case basis, although guidance on patient selection does exist.¹² The decision to operate and the extent of the surgical resection are nevertheless decided following physiological evaluation of the patient. This is made in conjunction with risk prediction, consent, shared decision making, and prehabilitation.

There are a range of systems currently used to risk stratify patients before thoracic surgery.¹³ Such systems have well-described flaws. Instead, a more holistic approach, considering patient factors beyond traditional measures of cardiorespiratory reserve, can provide a better understanding of perioperative risk. These additional measures can help highlight the presence of “red flags” to guide our decisions as to whether patients scheduled for surgery should fall into a high-risk category. These include, but are not limited to: low (and high) body mass index (>40 kg/m², BMI)¹⁴; low degree of functional independence; heavy nicotine dependence; heavy alcohol dependence; severe limitation of ability to walk short distances (unable to complete the 6 minutes walking test) or climb stairs; severe chronic cardiac disease, respiratory comorbidity and obstructive sleep apnea; and anemia; sarcopenia; and frailty. Risk assessment is integral to all prehabilitation programs, but prehabilitation should be for all patients, regardless of risk.

Shared Decision Making Versus Consent

Shared decision making can be defined as a process through which care is tailored to the values and choices of the patient and the expertise of the clinician.¹⁵ Confusion usually arises when the concept of shared decision making is conflated with consent, risk assessment, and decision aids or protocols.¹⁶ Despite general acceptance of its positive role in the perioperative period, the main barrier to its implementation is time. If the patient meets the anesthetist for the first time on the morning of surgery, the preoperative assessment will be more focused with information retrieval and navigating the choice of the safest anesthetic, long after the patient has agreed to surgery. For this reason, perioperative pathways must be reengineered toward contact with patient-anesthetists in the preoperative clinics, long before and after surgery, as shared decision making arguably extends into the postoperative period up to the time of discharge from the hospital. It is, therefore, integral to all prehabilitation programs.

Prehabilitation

The presurgical period is an ideal time for targeted interventions aimed at improving postoperative outcomes for all surgical patients. The aim is to restore physical and psychologic function following surgery. It is for all patients scheduled for surgery, and is not restricted to just those who are at high or low risk. It can be defined as “a process on the cancer continuum of care that occurs between the time of cancer diagnosis and the beginning of acute treatment and includes physical and psychologic assessments that establish a baseline functional level, identify impairments, and provide interventions that promote physical and psychologic health to reduce the incidence and/or severity of future impairments.”¹⁷ That said, it presents many challenges. Specifically, for thoracic surgical patients awaiting resection of cancer, there is limited time available between diagnosis and surgery, and other related hospital appointments or treatments might place a burden on the patient, both physically and psychologically. Prehabilitation must be multimodal. It is the sum of marginal gains from several interventions, which are themselves complementary.¹⁸ It requires invested resources, infrastructure, organization, and an acceptance of the longer-term benefits for surgical outcomes, value for money, and public health.¹⁹ Herein, we describe various components which might comprise a multimodal thoracic surgical prehabilitation program.

Exercise

Most published evidence in relation to thoracic prehabilitation focuses on data resulting from implementation of exercise programs.⁹ Most programs include aerobic training, resistance training, and respiratory muscle training, which may or may not be supervised.⁴ Although high-level evidence from two recent systematic reviews seems to suggest preoperative exercise programs in patients with lung cancer might be beneficial,⁴^,⁵ the included evidence was low to moderate. There are also questions about whether this evidence can be applied to lower risk populations and the resources required to implement these programs by organizations. Recently, guidelines on preoperative exercise training in patients awaiting major noncardiac surgery were published by Tew et al.²⁰ This provides a useful sample program of exercise aimed at reducing the incidence of postoperative complications in thoracic surgical patients. However, the authors concluded that successful implementation of prehabilitation programs may prove challenging. A range of institutionalized cultural and attitudinal barriers exist that could affect preoperative initiatives to varying degrees. Patient‐related factors include motivation, time and financial worries, and limiting comorbidities. System‐related barriers include lack of educational opportunities highlighting the benefits of exercise, insufficient infrastructure, and concerns about the feasibility of delivery and cost effectiveness of potential programs.

Nutrition

Low BMI is a known risk factor for patients undergoing lung resection surgery.²¹ This is a modifiable risk factor, and there exists several scoring systems to detect malnutrition.²² Every patient interaction is an opportunity to reinforce the importance of optimizing the nutritional state. Regarding perioperative malnutrition, there is no accepted definition, although this must account for under- and overnourished states. Although overnourished patients are at risk of postoperative complications, undernourished patients with lung cancer may be sarcopenic and have limited reserve to cope with the insult of surgery. Avoiding malnutrition and supporting anabolism are basic perioperative goals, and they can be met with screening, referral to dietetics, and nutritional prehabilitation.²³ This can take the form of oral nutritional supplements, vitamins, immunonutrition, protein, and carbohydrate loading.

Fig. 9.1 is reported by the American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on Nutrition Screening and Therapy Within a Surgical Enhanced Recovery Pathway. After literature review, they developed and proposed the perioperative nutrition screen (PONS). The PONS is a modified version of the malnutrition universal screening tool (MUST) that has been altered for use perioperatively. The PONS determines the presence of nutrition risk based on a patient’s BMI, recent changes in weight, reported recent decrease in dietary intake, and preoperative albumin level. In addition, the PONS includes evaluation of preoperative albumin level because this is a predictor of postoperative complications, including morbidity/mortality.²⁴

• Fig. 9.1 Perioperative nutrition screen (*PONS*). The PONS determines the presence of nutrition risk based on a patient’s body mass index, recent changes in weight, reported recent decrease in dietary intake, and preoperative albumin level. In addition, the PONS includes evaluation of a preoperative albumin level, as this is a predictor of postoperative complications, including morbidity/mortality. *BMI,* Body mass index. (From Gillis C, Wischmeyer PE. Pre-operative nutrition and the elective surgical patient: why, how and what? *Anaesthesia*. 2019;74:27–35.)

Surgical nutrition guidelines, such as the European Society for Clinical Nutrition and Metabolism, American Society of Parenteral Enteral Nutrition, and the American Society for Enhanced Recovery with Perioperative Quality Initiative all provide details on selecting nutrition screening tools, malnutrition assessment tools, and treatment for malnourished and at-risk patients. A comprehensive nutrition assessment involves understanding the personal cause(s) of malnutrition and correcting barriers to adequate food intake. Patients identified as malnourished, or at risk, require individualized treatment plans that may include therapeutic diets or fortified foods.

The Duke University PeriOperative Enhancement Team (POET) program is shown in Fig. 9.2. Any patient assessed as being at malnutrition risk (PONS score ≥ 1) is referred for evaluation by a dietitian and receives nutrition care according to this pathway.