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The use of cardiopulmonary exercise testing CPET to evaluate cardiac and respiratory function was pioneered as part of preoperative assessment in the mid s. Surgical procedures have changed since then.

Michael K. Stickland, Scott J. Butcher, Darcy D.

Assessing Exercise Limitation Using Cardiopulmonary Exercise Testing

The use of cardiopulmonary exercise testing CPET to evaluate cardiac and respiratory function was pioneered as part of preoperative assessment in the mid s. Surgical procedures have changed since then. The patient population may have aged; however, the physiology has remained the same. The use of an accurate physiological evaluation remains as germane today as it was then. The author recognizes that not everyone accepts the classical theories of the anaerobic threshold AT and that there is some discussion around lactate and exercise.

The article looks at aerobic capacity as an important predictor of perioperative mortality and also looks at some aspects of CPET relative to surgical risk evaluation. This was some years before the real magic, that of Lavoisier, was initiated.

Antoine Laurent Lavoisier was beheaded in during the French Revolution but not before he had measured oxygen uptake during exercise.

This provided the fundamental foundation for modern CPET. Lavoisier showed that during respiration oxygen is consumed and carbon dioxide is given off. At the beginning of the eighteenth century, chemistry was alchemy; by the end it was a science. For more detail on Lavoisier, the reader is referred to references [ 1 , 2 ]. Far from being magic, the measurement of oxygen uptake and the traditional exposition of the anaerobic threshold AT is the result of a logical physiological progression [ 3 ].

It is the epitome of Vorsprung durch Technik. This slogan, Progress through technology , has been used by Audi AG since So many famous names have pursued the concepts that underlie this physiology: Lavoisier, Krogh, Bohr, Henderson, Dill, Wasserman, Whipp, Jones, to name a few.

This statement was in direct conflict with the position of Christian Bohr, who believed there to be an active transport mechanism for the transport of oxygen across the alveoli. For a detailed discussion on the disagreement between these two titans, see [ 6 ]. Krogh had also developed a cycle ergometer with which he was able to measure insensible and sensible fluid losses accurately during heavy exercise [ 5 ].

In , Yandell Henderson named the oxygen pulse as a most important quantitative measurement. The Harvard Fatigue Laboratory, a laboratory of human physiology, was conceived in by LJ Henderson and began operation in The staff of the Harvard Fatigue Laboratory embraced a wide range of disciplines, including physiology, biochemistry, psychology, biology, medicine, sociology and anthropology.

The research performed by the laboratory reflected this diversity of backgrounds; areas of research included the physical chemistry of blood, exercise physiology, nutritional interactions, aging, and the stresses of high altitude and climate.

Equipment utilized by the staff in conducting research included treadmills, a climatic room, an altitude chamber and an animal room. The physiologist DB Dill was the director of the laboratory from to This laboratory was responsible for innumerable publications relating to exercise physiology [ 9 ]. Comroe asked Wasserman how patients could be screened, noninvasively if possible, for early detection of heart failure and other heart diseases K Wasserman, personal communication.

In , Naimark, Wasserman and McIlroy showed that exercise tests could usefully be employed to detect degrees of dysfunction in the cardiovascular system. The onset of anaerobic metabolism, the AT, during exercise could be detected in three ways; an increase in lactate concentration in the blood, a decrease in arterial bicarbonate concentration and pH, and an increase in the respiratory exchange ratio [ 10 , 11 ]. Wasserman showed that the lactic acid must be buffered, by the volatile buffer bicarbonate, producing an equal number of CO 2 molecules to be added to the CO 2 produced by aerobic metabolism.

Since rapidly responding gas analyzers had recently become available, Wasserman further suggested that the CO 2 produced by the bicarbonate buffering of lactic acid might be measured breath-by-breath. Comroe then suggested that Wasserman should pursue these ideas K Wasserman, personal communication.

His initial studies on the physiological underpinnings of this work were with Naimark and McIlroy. They showed how the respiratory exchange ratio could be measured on a continuous basis during exercise studies.

Further, they showed that the increase in the respiratory exchange ratio was related to work intensity [ 10 ]. Their first work on the AT was published in from Stanford [ 11 ]. Brian J Whipp, then a predoctoral Fellow with Wasserman at Stanford, moved with him: together they set up the exercise physiology research laboratory and collaborated in exercise physiology research.

With the development of digital computers later in the s, WL Beaver, a physicist working at Central Research at Varian Associates in Palo Alto, joined this investigation.

This collaboration enabled the use of digital computers for breath-by-breath exercise gas exchange [ 12 — 14 ]; Vorsprung durch Technik? Wasserman, with colleagues such as Brian Whipp, James Hansen, Daryl Sue, Kathy Sietsema, Dan Cooper, Richard Casaburi and William Stringer, became the driving force behind the development of cardiopulmonary exercise testing in the clinical environment. To this day, they still publish key literature on the information gained about cardiac and respiratory function from cardiopulmonary exercise testing.

Many other names deserve mention but the space available precludes that. Is there a threshold? If in there was still controversy over the term, then that alone warrants further examination of just why. The latest book by Wasserman et al. One issue that remains is the inter-rater and intra-rater repeatability of the data measurements, in particular the AT. This is impossible to quantify as it is related directly to the experience of the physicians.

In our laboratory it is uncommon, or rare, for there to be a significant disagreement. Anaerobic metabolism is not uniquely a feature of high intensity work rates; on the contrary it is found at low intensity work rates but does not represent a major component of energy transfer under those conditions.

It is probable that there is a degree of anaerobic metabolism at all work rates [ 17 ]. Certainly at the onset of exercise there is an increase in ATP demand. This is met from oxygen independent sources, such as phosphocreatine hydrolysis and glycolysis [ 18 ]. Further lactate, the most commonly quoted suspect as the end point of anaerobic metabolism, is falsely accused.

Lactate is a product in the pathway of energy production, not its endpoint. Lactate is produced by muscle tissue at rest in the absence of any cause of hypoxia [ 19 ]. It is now recognized that lactate present at the end of exercise is predominately oxidized [ 20 ]. Put another way, it is the highest work rate at which the concentration of lactate does not show a consistent increase.

The latter is accompanied by an increase in CO 2 output, a phenomenon that was used by Beaver and colleagues to estimate the AT by the almost universally used V-slope [ 12 ].

Clinically, this point is most commonly identified via a rapid incremental work-rate protocol on a cycle ergometer but it can also be achieved on a treadmill. In , Hopker et al. These authors suggested alternative explanations for the relationship between the conventionally estimated AT and surgical outcome.

Whipp and Ward strongly repudiate much of this article, strongly supporting the conventional concepts of the AT [ 23 ]. In their original article in , Wasserman and McIlroy [ 11 ] had pointed out that the onset of anaerobic metabolism can be detected in three ways: 1 as an increase in the lactate concentration in arterial blood; 2 as a decrease in arterial blood bicarbonate concentration and pH; and 3 as an increase in the respiratory exchange ratio.

Because of the accompanying hydrogen ion increase with lactate accumulation above the AT, and the buffer for the accumulating lactic acid being bicarbonate, CO 2 output increases independently of O 2 uptake above the AT. It was argued by Beaver et al. Be this as it may, bicarbonate is the only buffer that releases carbon dioxide into the blood. The fall in arterial bicarbonate concentration that occurs pari passu with this buffering is accompanied by an increase in arterial lactate concentration that is very close to a mirror change, in fact almost a millimole to millimole change [ 21 ].

Thus, at the time the arterial bicarbonate level is falling there will be an increase in CO 2 output and a rise in arterial lactate level. If arterial blood can be sampled at very short time intervals, it will be seen that the rise in lactate level occurs a few seconds before the change in bicarbonate level, [ 16 ] reflecting a small contribution from non-CO 2 -yielding buffers [ 26 ].

Whatever other buffers are involved at this time they will not affect this outcome. This point at which the arterial lactate concentration increases indeed represents the onset of lactate-related anaerobic metabolism. The temporal differences in metabolism will mean that the AT is identified at slightly different points. Simultaneous plot of lactate, base excess and gas exchange. This was obtained from a man exercising on a cycle ergometer. Samples at one minute intervals.

Note that the base excess falls very much as the reciprocal of the lactate rise. When the intensity of exercise increases, there will be a rapid formation of lactate at some point.

The rapidity of this change will depend on many factors but it typically will produce a threshold-like increase in arterial lactate, which may take the form of a rapid to very rapid change, that is, a threshold, in the graph of lactate concentration against time.

The rapidity of the change will depend on the rate of change of the work rate. It is important to remember that lactate is itself a fuel for muscle metabolism both locally during contraction and remotely in other muscle beds as well as the heart. The liver, during exercise, is not a major site of lactate clearance.

Thus lactate is not reliant on one method of removal from the blood stream [ 19 ]. This vindicates the use of the V-slope [ 14 ] method of determining the AT, which merely identifies this threshold point. It is important that hyperventilation, producing a rise in both ventilatory equivalents and a fall in end-tidal carbon dioxide tension, is not mistaken for the AT.

What then represents a reasoned approach to risk assessment of surgical patients using CPET? The rapid incremental test evaluates cardiovascular CVS , respiratory and peripheral muscle issues. This is a means of placing 15 variables onto 9 graphs and showing all the relevant results on one piece of paper. I will use this nine-panel format throughout this paper. Traditional nine-panel plot. This format emanates from Wasserman and colleagues.

This is one of several formats currently used but is by far the most common. The 9-panel format allows 15 variables to be plotted on 9 graphs. Note in Panel 7, the lines indicating vital capacity, inspiratory capacity and maximum ventilatory volume.

This is useful in assessing respiratory function. New nine-panel plot. This new format was first announced in [ 16 ]. Why is the V-slope so important? Almost every commercial metabolic cart, as a first option, estimates AT from the relationship between CO 2 output and oxygen uptake, also termed the V-slope. It is rare for the arterial lactate or bicarbonate levels to be actually measured.

Cardiopulmonary Exercise Testing

The clinical importance of cardiopulmonary exercise testing and aerobic training in patients with heart failure. Unfortunately, these systems are all negatively impacted in patients with heart failure HF , resulting in significantly diminished aerobic capacity compared with apparently healthy individuals. The values of several key variables obtained from CPX, such as peak oxygen consumption and ventilatory efficiency, are often found to be abnormal in patients with HF. In addition to the ability of CPX variables to acutely reflect varying degrees of pathophysiology, they also possess strong prognostic significance, further bolstering their clinical value. Once thought to be contraindicated in patients with HF, participation in a chronic aerobic exercise program is now an accepted lifestyle intervention. These exercise-induced adaptations to physiological function result in a significant improvement in aerobic capacity and quality of life. This paper provides a review of the literature highlighting the clinical significance of aerobic exercise testing and training in this unique cardiac population.

Karlman Wasserman, MD Use of CPX in the clinical evaluation of chronic dyspnea. Balady G J et al. Circulation. Wear loose fitting clothes, low-heeled or athletic shoes Principles of Exercise Testing and Interpretation, 5th edition, Dr.

Assessing Exercise Limitation Using Cardiopulmonary Exercise Testing

Made with FlippingBook. Principles of exercise testing and interpretation: including pathophysiology and clinical applications. Philadelphia: Lippincott Williams andWilkins;

Nicholas M. Beltz, Ann L. Gibson, Jeffrey M. Janot, Len Kravitz, Christine M.

Download PDF. Abstract: In patients presenting cardiovascular, pulmonary, muscular and metabolic diseases, exercise testing continues to be a predictive and diagnosis source of information. Diagnosis and assessment of coronary artery disease known or suspected encompass clinical and risk factors evaluation and well-defined non-invasive and invasive tests.

Anaerobic threshold, is it a magic number to determine fitness for surgery?

The committee aims to serve as a resource for consultative cardiovascular assessment of highly active individuals as well as a home for educational tools to aid in their assessment and management. The Cardiopulmonary Exercise Test Introduction Physical activity requires the integrated performance of cardiovascular, pulmonary, metabolic, and neuromuscular systems.

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The occurrence of minute-ventilation oscillations during exercise, named periodic breathing, exhibits important prognostic information in heart failure.

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Request PDF | Principles of exercise testing and interpretation: Including For comparison we used the Hansen-Wasserman's 6, 7 and the Fitness Registry and the individual's health condition and activity habit so that the duration of CPX was cortex to physical capacity in athletes and patients with chronic heart failure.

Gary C. 16.12.2020 at 11:36

abbreviated as CPX) is the determination of a person's performance during physical Wasserman (simplified), illustrates so concisely below: Editorial speed or power of the athlete. When measuring Principles of Exercise Testing and Interpretation 3rd edition Web-based evaluation and interpretation of PDF reports.

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