'X-rays don't tell lies': the Medical Research Council and the measurement of respiratory disability, 1936-1945.

During the first half of the twentieth century, the mining industry in Britain was subject to recurrent disputes about the risk to miners' lungs from coal dust, moderated by governmental, industrial, medical and mining bodies. In this environment, precise measurements offered a way to present uncontested objective knowledge. By accessing primary source material from the National Archives, the South Wales Miners Library and the University of Bristol's Special Collections, I demonstrate the importance that the British Medical Research Council (MRC) attached to standardized instrumental measures as proof of objectivity, and explore the conflict between objective and subjective measures of health. Examination of the MRC's use of spirometry in their investigation of pneumoconiosis (miner's lung) from 1936 to 1945 will shed light on this conflict and illuminate the politics inherent in attempts to quantify disability and categorize standards of health.

Classical experiments in whole-body metabolism: open-circuit respirometry-diluted flow chamber, hood, or facemask systems.

For over two centuries, scientists have measured gas exchange in animals and humans and linked this to energy expenditure of the body. The aim of this review is to provide a comprehensive overview of open-circuit diluted flow indirect calorimetry and to help researchers to make the optimal choice for a certain system and its application. A historical perspective shows that 'open circuit diluted flow' is a technique first used in the 19th century and applicable today for room calorimeters, ventilated hood systems, and facemasks. Room calorimeters are a classic example of an open-circuit diluted flow system. The broadly applied ventilated hood calorimeters follow the same principle and can be classified as a derivative of these room calorimeters. The basic principle is that the subject breathes freely in a passing airflow that is fully captured and analyzed. Oxygen and CO2 concentrations are measured in inlet ambient air and captured outlet air. The airflow, which is adapted depending on the application (e.g., rest versus exercise), is measured. For a room indirect calorimeter, the dilution in the large room volume is also taken into account, and this is the most complex application of this type of calorimeter. Validity of the systems can be tested by alcohol burns, gas infusions and by performing repeated measurements on subjects. Using the latter, the smallest CV (%) was found for repeated VO2max tests (1.2%) with an SD of approximately 1 kJ min-1. The smallest SD was found for sleeping metabolic rate (0.11 kJ min-1) with a CV (%) of 2.4%.

Foundational insights into the estimation of whole-body metabolic rate.

Since 2013, this journal has promoted the publication of thematic reviews (Taylor in Eur J Appl Physiol 113:1634, 2013), where leading groups were invited to review the critical literature within each of several sub-topics. The current theme is historically based, and is focussed on estimating the metabolic rate in humans. This review charts the development of our understanding of those methods, from the discovery of oxygen and carbon dioxide, to the introduction of highly sophisticated modern apparatus to examine the composition of expired gas and determine respiratory minute volume. An historical timeline links the six thematic vignettes on this theme. Modern advances have greatly enhanced data collection without significant decrements in measurement accuracy. At the same time, however, conceptual errors, particularly steady-state requirements, are too often ignored. Indeed, it is recognised that we often neglect the past, leading to errors in research design, experimental observations and data interpretation, and this appears to be increasingly prevalent within the open-access literature. Accordingly, the Editorial Board, in recognition of a widening gap between our experimental foundations and contemporary research, embarked on developing a number of thematic review series, of which this series is the first. The intent of each accompanying overview is to introduce and illuminate seminal investigations that led to significant scientific or intellectual breakthroughs, and to thereby whet the appetite of readers to delve more deeply into the historical literature; for it is only when the foundations are understood that we can best understand where we are now, and in which directions we should head.

Open-circuit respirometry: a brief historical review of the use of Douglas bags and chemical analyzers.

The Douglas bag technique is reviewed as one in a series of articles looking at historical insights into measurement of whole body metabolic rate. Consideration of all articles looking at Douglas bag technique and chemical gas analysis has here focused on the growing appreciation of errors in measuring expired volumes and gas composition, and subjective reactions to airflow resistance and dead space. Multiple small sources of error have been identified and appropriate remedies proposed over a century of use of the methodology. Changes in the bag lining have limited gas diffusion, laboratories conducting gas analyses have undergone validation, and WHO guidelines on airflow resistance have minimized reactive effects. One remaining difficulty is a contamination of expirate by dead space air, minimized by keeping the dead space <70 mL. Care must also be taken to ensure a steady state, and formal validation of the Douglas bag method still needs to be carried out. We may conclude that the Douglas bag method has helped to define key concepts in exercise physiology. Although now superceded in many applications, the errors in a meticulously completed measurement are sufficiently low to warrant retention of the Douglas bag as the gold standard when evaluating newer open-circuit methodology.

Classical experiments in whole-body metabolism: closed-circuit respirometry.

As part of a series of reviews aimed at providing historical context to the study of whole-body metabolism, this article focuses on the technique of closed-circuit respirometry. Developed by nineteenth century physiologists Henri-Victor Regnault and Jules de Reiset, a constant-pressure closed-circuit calorimeter capable of measuring oxygen consumption and carbon dioxide production in small animals became the framework for future experiments on whole-body metabolism in humans. The volume-loss and volume-replenishment techniques can be used to indirectly assess energy expenditure using an oxygen reservoir; spirometers are simplistic in design but difficult to operate. Leaks, calibration errors, equilibration of gases and dead space are some of the major limitations of the methodology. Despite operational difficulties, closed-circuit respirometry is highly accurate and reproducible. Due to the bespoke nature of many closed-circuit systems, maintenance and repair is often troublesome. Compounded by technological advancement, closed-circuit techniques have become progressively outdated. Nevertheless, the classical experiments in whole-body metabolism played a pivotal role in furthering our understanding of basic human physiology and paved the way for current methodologies used in the field.

Open-circuit respirometry: a historical review of portable gas analysis systems.

Scientists such as physiologists, engineers, and nutritionists have often sought to estimate human metabolic strain during daily activities and physical pursuits. The measurement of human metabolism can involve direct calorimetry as well as indirect calorimetry using both closed-circuit respirometry and open-circuit methods that can include diluted flow chambers and laboratory-based gas analysis systems. For field studies, methods involving questionnaires, pedometry, accelerometery, heart rate telemetry, and doubly labelled water exist, yet portable metabolic gas analysis remains the gold standard for most field studies on energy expenditure. This review focuses on research-based portable systems designed to estimate metabolic rate typically under steady-state conditions by critically examining each significant historical innovation. Key developments include Zuntz's 1906 innovative system, then a significant improvement to this purely mechanical system by the widely adopted Kofranyi-Michaelis device in the 1940s. Later, a series of technical improvements: in electronics lead to Wolf's Integrating Motor Pneumotachograph in the 1950s; in polarographic O2 cells in 1970-1980's allowed on-line oxygen uptake measures; in CO2 cells in 1990s allowed on-line respiratory exchange ratio determination; and in advanced sensors/computing power at the turn of the century led to the first truly breath-by-breath portable systems. Very recent significant updates to the popular Cosmed and Cortex systems and the potential commercial release of the NASA-developed 'PUMA' system show that technological developments in this niche area are still incrementally advancing.

Race Correction and Spirometry: Why History Matters.

In recent months, medical institutions across the United States redoubled their efforts to examine the history of race and racism in medicine, in classrooms, in research, and in clinical practice. In this essay, I explore the history of racialization of the spirometer, a widely used instrument in pulmonary medicine to diagnose respiratory diseases and to assess eligibility for compensation. Beginning with Thomas Jefferson, who first noted racial difference in what he referred to as "pulmonary dysfunction," to the current moment in clinical medicine, I interrogate the history of the idea of "correcting" for race and how researchers explained difference. To explore how race correction became normative, initially just for people labeled "black," I examine visible and invisible racialized processes in scientific practice. Over more than two centuries, as ideas of innate difference hardened, few questioned the conceptual underpinnings of race correction in medicine. At a moment when "race norming" is under investigation throughout medicine, it is essential to rethink race correction of spirometric measurements, whether enacted through the use of a correction factor or through the use of population-specific standards. Historical analysis is central to these efforts.

A review of the role of FEV1 in the COPD paradigm.

Historically, spirometry has been the objective measure used to confirm a symptom-based clinical suspicion of COPD. The third National Health and Nutrition Examination Survey (NHANES III) created a strong rationale for early identification and intervention in COPD by documenting the ability of spirometry to detect mild airflow problems in many asymptomatic smokers. Predicted values for spirometry, however, must be adjusted to account for variations in age, gender, height, ethnicity and race. Many experts agree that NHANES III reference equations are much better suited to COPD practice than most other predicted value standards. However, standards other than NHANES III have been adopted in current medical guidelines; standards that may inappropriately classify younger adults as normal and older adults as abnormal, potentially leading to widespread misdiagnosis and mis-directed therapies in clinical practice. Despite the shortcomings of established diagnostic predicted values, spirometry remains the best available tool for early and accurate diagnosis of COPD in those at risk for the disease, and is also useful in conjunction with other modalities in patients with established disease to determine prognosis and assessing therapeutic benefits. In the clinical trial settings, as well as in day-to-day practice, spirometry results should be combined with other endpoints in order to better reflect overall patient status. This review highlights key medical evidence surrounding both usefulness and limitations of FEV(1) in the setting of COPD.

Portable open-circuit spirometry systems.

BACKGROUND: The purpose of this review is to describe the evolution of portable open-circuit spirometry systems, and discuss their validity, reliability, and principles of operation. METHODS: Eleven devices were selected for review: the Oxylog, Aerosport KB1-C, Cosmed K2, Cosmed K4RQ, Cosmed K4b2, MetaMax I, MetaMax II, Metamax3B/VmaxST, Medgraphics VO2000, Oxycon Mobile I and Oxycon Mobile II. The validity (compared to the Douglas bag method [DBM]) and reliability of each device for measuring VO2 was summarized. RESULTS: Mean differences in resting measurements of VO2 were within ±0.05 L/min for all devices except one (difference of 0.17 L/min). When compared to the DBM, VO2 differences for all devices ranged from 0.01 L/min to 0.29 L/min during submaximal intensity exercise and from 0.01 L/min to 0.36 L/min during vigorous/maximal intensity. During submaximal and maximal intensities, ICC ranged from 0.66-0.99 and CV ranged from 2.0-14.2%. Of these devices, four used breath-by-breath technology and six used micro-proportional sampling technology. Validity and reliability of devices did not seem to differ between methods of gas collection. CONCLUSIONS: Of the three commercially available devices in 2015, all were found to be reliable. Two of the three systems (Cosmed K4b2 and Oxycon Mobile II) provided valid estimates of VO2 (mean values within ±0.10 L/min of DBM) during rest, and submaximal and maximal intensities, while the MetaMax3B slightly overestimated VO2, particularly at maximal exercise.

Metabolism: The Physiological Power-Generating Process: A History of Methods to Test Human Beings' \"Vital Capacity\" [Retrospectroscope].

A previous "Retrospectroscope" note, published early in 2014, dealt with spirometry: it described many apparatuses used to measure the volume of inhaled and exhaled air that results from breathing [1]. Such machines, when adequately modified, are also able to measure the rate at which work is produced (specifically by an animal or a human being). Metabolism in that sense is the term used by physiologists and physicians, a word that in Greek, metabolismos, means "change" or "overthrow," in the sense of breaking down material, as in burning some stuff.

John Hutchinson's mysterious machine revisited.

John Hutchinson, a surgeon, recognized that the volume of air that can be exhaled from fully inflated lungs is a powerful indicator of longevity. He invented the spirometer to measure what he called the vital capacity, ie, the capacity to live. Much later, the concept of the timed vital capacity, which became known as the FEV(1), was added. Together, these two numbers, vital capacity and FEV(1), are useful in identifying patients at risk of many diseases, including COPD, lung cancer, heart attack, stroke, and all-cause mortality. This article cites some of the rich history of the development of spirometry, and explores some of the barriers to the widespread application of simple spirometry in the offices of primary care physicians.

Ergospirometry and its history.

Ergospirometry is a diagnostic procedure to continuously measure respiration and gas metabolism during ergometer exercise. It enables judgement of function and performance capacity of the cardiopulmonary system and metabolism. Ergospirometry is made up of the 2 components spirometry and ergometry. The first attempts to measure human gas metabolism while performing quantified physical work can be traced back to the year 1790. The development of procedures to measure gas metabolism and respiration as well as the construction of ergometers in the nineteenth and twentieth centuries are described. Ergospirometry and routinely performed clinical performance diagnosis were introduced in 1929, but it was not until the 1950s when the first ergospirometry apparatus which met all scientific requirements was developed. The parameters used and the physiological and pathophysiological findings by ergospirometry are given in an historical frame. Numerous medical fields have profited from the technique of ergospirometry, for example: cardiology, pneumology, sports medicine, exercise physiology, biochemistry, clinical pharmacology, surgery, orthopaedics, paediatrics and gerontology, besides such global disciplines as preventive medicine, exercise therapy and rehabilitative medicine.

42 years ago--development of the concepts of ventilatory and lactate threshold.

At the Third Pan-American Congress of Sport Physicians in Chicago in 1959 we reported the physiological and clinical significance of the spiroergometric determination of the aerobic-anaerobic turnover point for judging the performance of sick and healthy persons for the first time. In this context a distinction was made between a ventilatory and a lactate-related (arterial blood) method of determination. We called the former method the 'point of optimal ventilatory efficiency (PoW)', and the latter one 'endurance performance limit'. In the 1950s the clinical spiroergometric examination of patients and athletes for the determination of the aerobic performance capacity was consistently based on the measurement of the maximal oxygen uptake. As entering the individual border area of the performance capacity of a patient with, for example, cardiopulmonary disease, can provoke accidents, we started to think about a criterion in connection with submaximal work in 1954. Determination of pyruvate and lactic acid in the venous blood did not prove to be a valid parameter. If the spiroergometric values were entered into a coordinate system the most striking similarities during increasing exercise would become evident between the curve of the minute ventilation and the curve of the arterial lactate. The findings were interpreted as follows: during lower grades of performance the oxygen demand in the working muscle cells was saturated, whereas in the case of increasing exercise intensity an additional anaerobic metabolism was necessary. We termed the maximal work load which was covered nearly completely aerobically as the PoW and designated heart frequency at this point as 'pulse endurance limit'. The determination of the parameter was derived in the coordinate system with a tangent to the curve of the minute ventilation as well as to the curve of the arterial lactate. The results of patients and athletes were first published in 1959.

[Forced expiration. Various current concepts, 50 years after Robert Tiffeneau]. / Expiration forcée. Quelques concepts actuels, 50 ans après Robert Tiffeneau.

One hundred and fifty years after the original description of spirometry by Hutchinson and 50 years after the definition of his famous ratio by Tiffeneau, a certain number of physiological advances have enabled a better understanding of the determinants of the forced expired manoeuvre and to mitigate some of its inconveniences. This review focuses on three of these advances. The first is the influence of an inspiratory manoeuvre which precedes a forced expiration, on the expiratory flow. This influence is probably a consequence of viscoelastic phenomena and impose some strains on standardisation in current practice. The second is the possibility of detecting in a reproducible and simple fashion, without the need for co-operation on the part of the subject, a limitation in expiratory flow by the application of a negative expiratory pressure at the opening of the airways (NEP for negative expiratory pressure). The third is the possibility to verify in a simple fashion the quality of the expiratory performance achieved by the patient and thus to detect an insufficient effort in the force of a falling expiratory flow.

Chronic obstructive pulmonary disease and '150 years of blowing'.

Spirometry is now an established and important aspect of investigation of many lung diseases. This article considers the history of spirometry, how we come to use the current indices of dynamic lung function, and the role of spirometry in the management of patients with chronic obstructive pulmonary disease.

[The fiftieth anniversary of Miodonski's electro-rhino-spirometry]. / Piecdziesieciolecie elektrorynospirometrii Miodonskiego.

On the 50th anniversary of the introduction of the electro-rhino-spirometry by Miodonski the author recalls its theoretical foundations and diagnostic possibilities. Moreover, it has been stressed that Miodonski's method was the first one which does not disturb the nasal function, and the development of electronics supported and widened its diagnostic possibilities leaving the theoretical basis for examination unchanged.