Preoperative cardiopulmonary exercise testing: physiological basis and investigation

The number of cardiopulmonary exercise testing (CPET) centres has doubled in the UK since 2011. Approximately 30,000 tests are performed every year in the UK now. It is a useful tool helping preoperative risk stratification. Patients with poor exercise tolerance are more likely to suffer perioperative complications and death. Interpretation of a large amount of data generated during the test requires a good understanding of basic exercise physiology and its clinical application. Incorporation of CPET data in a global preoperative assessment provides a personalized risk estimate for a patient. This risk estimate discussed with the multidisciplinary team and the patient is an opportunity to make a decision which is in the patient’s best interest. Such decisions also help in the best use of healthcare resources. Newer studies in this field are addressing the ongoing debate about the future use of CPET-derived parameters.     

Preoperative cardiopulmonary exercise testing: physiological basis and investigation

The number of cardiopulmonary exercise testing (CPET) centres has doubled in the UK since 2011. Approximately 30,000 tests are performed every year in the UK now. It is a useful tool helping preoperative risk stratification. Patients with poor exercise tolerance are more likely to suffer perioperative complications and death. Interpretation of a large amount of data generated during the test requires a good understanding of basic exercise physiology and its clinical application. Incorporation of CPET data in a global preoperative assessment provides a personalized risk estimate for a patient. This risk estimate discussed with the multidisciplinary team and the patient is an opportunity to make a decision which is in the patient's best interest. Such decisions also help in the best use of healthcare resources. Newer studies in this field are addressing the ongoing debate about the future use of CPET-derived parameters.     

Physiological basis of preoperative cardiopulmonary exercise testing

The use of cardiopulmonary exercise testing (CPET) is gaining popularity as a preoperative functional assessment tool and a useful adjunct to risk stratification before surgery. Determination of the integrated response of multiple body systems (including the cardiorespiratory and peripheral oxygen delivery systems) to exercise stress, adds important prognostic value to pre-surgical assessment, shared-decision making and postoperative management of the surgical patient. Thorough CPET interpretation is complex but may be assisted by an understanding of basic exercise physiology and its application to the preoperative context.     

Physiological basis of preoperative cardiopulmonary exercise testing

The use of cardiopulmonary exercise testing (CPET) is gaining popularity as a preoperative functional assessment tool and is a useful adjunct to risk stratification before surgery. Determination of the integrated response of multiple body systems (including the cardiorespiratory and peripheral oxygen delivery systems) to exercise stress, adds important prognostic value to pre-surgical assessment, shared-decision making and post-operative management of the surgical patient. Thorough CPET interpretation is complex but may be assisted by an understanding of basic exercise physiology and its application to the preoperative context.     

Perioperative cardiopulmonary exercise testing in the elderly

The elderly constitute an increasingly large segment of the population and of the patients requiring medical attention. Major surgery is associated with a substantial burden of postoperative morbidity and mortality. Advancing age is a particular risk factor for these outcomes. This article reviews the current literature on the value and practical applications of cardiopulmonary exercise testing (CPET) as a tool to evaluate risk and thereby improve the management of the elderly patient undergoing major surgery. There is a consistent association between CPET-derived variables and outcome following major surgery. Furthermore, CPET-derived variables have utility in perioperative risk prediction and identification of patients at high risk of adverse outcome following major surgery. This optimal predictor appears to differ between various surgery types and the incremental benefit of combining CPET with alternative methods of perioperative risk prediction remains poorly defined.     

Perioperative cardiopulmonary exercise testing (CPET): consensus clinical guidelines on indications,organization, conduct,and physiological interpretation

The use of perioperative cardiopulmonary exercise testing (CPET) to evaluate the risk of adverse perioperative events and inform the perioperative management of patients undergoing surgery has increased over the last decade. CPET provides an objective assessment of exercise capacity preoperatively and identifies the causes of exercise limitation. This information may be used to assist clinicians and patients in decisions about the most appropriate surgical and non-surgical management during the perioperative period. Information gained from CPET can be used to estimate the likelihood of perioperative morbidity and mortality, to inform the processes of multidisciplinary collaborative decision making and consent, to triage patients for perioperative care (ward vs critical care), to direct preoperative interventions and optimization, to identify new comorbidities, to evaluate the effects of neoadjuvant cancer therapies, to guide prehabilitation and rehabilitation, and to guide intraoperative anaesthetic practice. With the rapid uptake of CPET, standardization is key to ensure valid, reproducible results that can inform clinical decision making. Recently, an international Perioperative Exercise Testing and Training Society has been established (POETTS www.poetts.co.uk) promoting the highest standards of care for patients undergoing exercise testing, training, or both in the perioperative setting. These clinical cardiopulmonary exercise testing guidelines have been developed by consensus by the Perioperative Exercise Testing and Training Society after systematic literature review. The guidelines have been endorsed by the Association of Respiratory Technology and Physiology (ARTP).     

Ammonium transport in the kidney: new physiological concepts and their clinical implications

This article is based on a Basic Science Symposium presented at the 23rd Annual Meeting of the American Society of Nephrology. New information on the segmental transport of ammonium by the proximal tubule, the thick ascending limb of Henle's loop, and the collecting duct is integrated into a thesis that NH4+ excretion is controlled by the rate of production, by diffusion of NH3 along gradients established by proton secretion, and by active transport of NH4+. These new concepts are applied to a novel explanation of the pathogenesis of distal renal tubular acidosis.     

Diagnosis of pulmonary vascular limit to exercise by cardiopulmonary exercise testing.

BACKGROUND: Given the recent development of newer and less-invasive treatments for pulmonary hypertension, and the long wait for lung transplantation, early and correct diagnosis of this condition is increasingly important. The purpose of this study was to determine and improve the accuracy of a non-invasive, cardiopulmonary exercise-testing algorithm for detecting a pulmonary vascular limit to exercise. METHODS: We performed 130 consecutive, incremental cycling-exercise tests for exertional symptoms with pulmonary and radial artery catheters in place. Pulmonary vascular limit was defined as pulmonary vascular resistance at maximum exercise >120 dynes. sec/cm(5) and a peak-exercise systemic oxygen delivery <80% predicted, without a pulmonary mechanical limit or poor effort. We applied a previously reported non-invasive exercise-test-interpretation algorithm to each patient and sequentially manipulated branch point threshold values to maximize accuracy. RESULTS: The sensitivity of the original non-invasive algorithm for pulmonary vascular limit was 79%, specificity was 75%, and accuracy was 76%. Sensitivity did not change with systematic alteration of branch-point threshold values, but specificity and accuracy improved to 88% and 85%, respectively. Accuracy improved most by modifying the threshold values for percent predicted maximum oxygen uptake and carbon dioxide output ventilatory equivalents at lactate threshold. CONCLUSION: Non-invasive cardiopulmonary exercise testing is a useful tool for detecting and excluding a pulmonary vascular limit and for determining whether abnormal pulmonary hemodynamics limit aerobic capacity.     

Preoperative cardiopulmonary exercise testing: determining the limit to exercise and predicting outcome after thoracotomy.

Over the past 15 years evaluation of the patient with exertional complaints has changed from a simple qualitative estimate of overall fitness to a detailed assessment of cardiovascular and pulmonary pathophysiology. By quantifying exercise impairment and identifying the physiological limit to exercise, CPEx can help direct and evaluate the efficacy of medical and surgical interventions. Although no clear consensus has emerged, an objective determination of the etiology of exercise intolerance may also help identify the patient at increased risk for postthoracotomy complications.     

Plyometric exercise in the rehabilitation of athletes: physiological responses and clinical application

Plyometric exercise was initially utilized to enhance sport performance and is more recently being used in the rehabilitation of injured athletes to help in the preparation for a return to sport participation. The identifying feature of plyometric exercise is a lengthening of the muscle-tendon unit followed directly by shortening (stretch-shortening cycle). Numerous plyometric exercises with varied difficulty and demand on the musculoskeletal system can be implemented in rehabilitation. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels. The progression to higher-intensity plyometric exercise is thought to resolve postinjury neuromuscular impairments and to prepare the musculoskeletal system for rapid movements and high forces that may be similar to the demands imposed during sport participation, thus assisting the athlete with a return to full function. While there is a large body of scientific literature that supports the use of plyometric exercise to enhance athletic performance, evidence is sparse regarding the effectiveness of plyometric exercise in promoting a quick and safe return to sport after injury. This review will describe the mechanisms involved in plyometric exercise, discuss the considerations for implementing plyometric exercise into rehabilitation protocols, examine the evidence supporting the use of plyometric exercises, and make recommendations for future research.