Prehabilitation for Thoracic Surgery

Introduction

Lung cancer accounts for 30% of all cancer cases, with outcomes for patients improving at a modest pace. That said, 5-year survival for patients with stage IA to IIA cancer managed with a combination of chemotherapy and surgery exceeds 50%. Lung cancer screening programs are increasingly used to identify patients at a stage where lung resection is possible. Lung resection surgery is associated with a high incidence of postoperative pulmonary complications, which are themselves associated with reduced survival, increased morbidity, and a prolonged intensive care and hospital length of stay. ^, Enhanced recovery after surgery protocols and postoperative pulmonary rehabilitation are now engrained in perioperative pathways, 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. 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. Respiratory mechanics are assessed by measuring the forced expiratory volume in one second (FEV ₁ ), 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 FEV ₁ 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 (VO ₂ ). If the peak or predicted postoperative VO ₂ is less than 35% or less than 10 mL/kg/min, a lobectomy or pneumonectomy are not recommended. 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. 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. 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/m ² , BMI) ; 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. Confusion usually arises when the concept of shared decision making is conflated with consent, risk assessment, and decision aids or protocols. 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.” 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.