Otto JM; Plumb JOM; Wakeham D; Clissold E; Loughney L; Schmidt W; Montgomery HE; Grocott MPW; Richards T

British Journal Of Anaesthesia [Br J Anaesth] 2017 May 01; Vol. 118 (5), pp. 747-754.

Background: Cardiopulmonary exercise testing (CPET) measures peak exertional oxygen consumption ( V˙O2peak ) and that at the anaerobic threshold ( V˙O2 at AT, i.e. the point at which anaerobic metabolism contributes substantially to overall metabolism). Lower values are associated with excess postoperative morbidity and mortality. A reduced haemoglobin concentration ([Hb]) results from a reduction in total haemoglobin mass (tHb-mass) or an increase in plasma volume. Thus, tHb-mass might be a more useful measure of oxygen-carrying capacity and might correlate better with CPET-derived fitness measures in preoperative patients than does circulating [Hb].
Methods: Before major elective surgery, CPET was performed, and both tHb-mass (optimized carbon monoxide rebreathing method) and circulating [Hb] were determined.
Results: In 42 patients (83% male), [Hb] was unrelated to V˙O2 at AT and V˙O2peak ( r =0.02, P =0.89 and r =0.04, P =0.80, respectively) and explained none of the variance in either measure. In contrast, tHb-mass was related to both ( r =0.661, P <0.0001 and r =0.483, P =0.001 for V˙O2 at AT and V˙O2peak , respectively). The tHb-mass explained 44% of variance in V˙O2 at AT ( P <0.0001) and 23% in V˙O2peak ( P =0.001). Conclusions: In contrast to [Hb], tHb-mass is an important determinant of physical fitness before major elective surgery. Further studies should determine whether low tHb-mass is predictive of poor outcome and whether targeted increases in tHb-mass might thus improve outcome.

Mezzani A; Spa SB,

Annals Of The American Thoracic Society [Ann Am Thorac Soc] 2017 May 16. Date of Electronic Publication: 2017 May 16.

Cardiopulmonary exercise testing adds measurement of ventilation and volume of oxygen uptake and exhaled carbon dioxide to routine physiological and performance parameters obtainable from conventional exercise testing, furnishing an all-round vision of the systems involved in both oxygen transport from air to mitochondria and its utilization during exercise. Peculiarities of cardiopulmonary exercise testing methodology are the use of ramp protocols and calibration procedures for flow meters and gas analyzers. Among the several parameters provided by this technique, peak oxygen uptake, first and second ventilatory thresholds, respiratory exchange ratio, oxygen pulse, slope of ventilation divided by exhaled carbon dioxide relationship, exercise oscillatory ventilation, circulatory power and partial pressure of end-tidal carbon dioxide are among the most relevant in the clinical setting. The choice of parameters to be considered will depend on the indication to cardiopulmonary exercise testing in the individual subject or patient, namely, exercise tolerance assessment, prognostic stratification, training prescription, treatment efficacy evaluation, diagnosis of causes of unexplained exercise tolerance reduction or exercise (patho)physiology evaluation for research purposes. Overall, cardiopulmonary exercise testing is a methodology now widely available and supported by a sound scientific evidence. Despite this, its potential still remains largely underused. Strong efforts and future investigations are needed to address these issues and further promote the use of cardiopulmonary exercise testing in the clinical and research setting.

Liu HJ, Guo J, Zhao QH, Wang L, Yang WL, He J, Gong SG, Liu
JM

Am J Med Sci. 2017 Mar;353(3):216-223. doi: 10.1016/j.amjms.2016.12.015. Epub
2016 Dec 21.

BACKGROUND: To study the relationship between chronotropic incompetence (CI) and
disease severity and to assess the effect of CI on exercise capacity in patients
with chronic obstructive pulmonary disease (COPD).
MATERIALS AND METHODS: Arterial blood gas analysis, pulmonary function test and
cardiopulmonary exercise testing were conducted in 60 patients with stable COPD
and 45 healthy volunteers. CI was defined using the chronotropic response index
(CRI = (peak heart rate-resting heart rate) / (220-age-resting heart rate). Based
on CRI, patients with COPD were divided into the normal chronotropic group (n =
23) and CI group (n = 37).
RESULTS: CI was present in 61.7% of the patients with COPD. Exercise capacity
(peak oxygen uptake as percentage of predicted value, peak VO2%pred), peak heart
rate and CRI were significantly lower in patients with COPD than in controls.
However, resting heart rate was significantly higher than in controls. FEV1%pred
and exercise capacity were significantly decreased in the CI group when compared
with those in the normotropic group. There was significant association between
CRI with FEV1%pred and peak VO2%pred. Multivariate regression analysis showed
that CRI and FEV1%pred were independent predictors of exercise capacity in
patients with COPD. A cutoff of 0.74 for the CRI showed a specificity of 94.1% in
predicting patients with a peak VO2%pred < 60%. CONCLUSIONS: CRI was associated with disease severity in patients with COPD. CI may be an important parameter to reflect exercise capacity in patients with COPD.

Tomlinson OW, Barker AR, Oades PJ, Williams CA.

Med Sci Sports Exerc. 2017 May 9. doi: 10.1249/MSS.0000000000001314. [Epub ahead
of print]

PURPOSE: The aim of this study was to describe the relationship between body size
and the oxygen uptake efficiency slope (OUES) in paediatric patients with cystic
fibrosis (CF) and healthy controls (CON), in order to identify appropriate
scaling procedures to adjust the influence of body size upon OUES.
METHODS: The OUES was derived using maximal and submaximal points from
cardiopulmonary exercise testing in 72 children (36 CF and 36 CON). OUES was
subsequently scaled for stature, body mass (BM) and body surface area (BSA) using
ratio-standard (Y/X) and allometric (Y/X) methods. Pearson’s correlation
coefficients were utilised to determine the relationship between body size and
the OUES.
RESULTS: When scaled using the ratio-standard method, OUES had a significant
positive relationship with stature (r = 0.54, P < 0.001) and BSA (r = 0.25, P = 0.031) and significant negative relationship with BM (r = -0.38, P = 0.016) in the CF group. Combined allometric exponents (b) for CF and CON were: stature 3.00, BM 0.86, BSA 1.40. A significant negative correlation was found between OUES and stature in the CF group when scaled allometrically (r = -0.37, P = 0.027). Non-significant (P > 0.05) correlations for the whole group were found
between OUES and allometrically scaled BM (CF: r = -0.25, CON: r = 0.15) and BSA
(CF r = -0.27, CON r = 0.13).
CONCLUSIONS: Only allometric scaling of either BM or BSA, and not ratio-standard
scaling, successfully eliminates the influence of body size upon OUES. Therefore
this enables a more direct comparison of the oxygen uptake slope between patients
with CF and healthy controls.

Vignati C, Cattadori G

Ann Am Thorac Soc. 2017 Apr 25. doi: 10.1513/AnnalsATS.201611-852FR. [Epub ahead
of print]

Cardiac output is a key parameter in the assessment of cardiac function, and its
measurement is fundamental to the diagnosis, treatment, and prognostic evaluation
of all heart diseases. Until recently, cardiac output determination during
exercise had been only possible through invasive methods, which were not
practical in the clinical setting. Since oxygen uptake (V.O2) is cardiac output
times arteriovenous content difference [C(a-v)O2)], evaluation of cardiac output
is usually included its measurement. Because of the difficulty of directly
measuring peak exercise cardiac output, indirect surrogate parameters have been
proposed, but with only modest clinical usefulness. Direct measurement of cardiac
output can now be made by several noninvasive measurements, such as rebreathing
inert gases, impedance cardiology, thoracic bioreactance, estimated continuous
cardiac output (EsCCO) technology, and transthoracic echocardiography coupled to
cardiopulmonary exercise testing allow more definitive results and better
understanding of the underlying physiopathology.

Agostoni P, Corrà U, Emdin M.

Ann Am Thorac Soc. 2017 Apr 26. doi: 10.1513/AnnalsATS.201701-003FR. [Epub ahead
of print]

Periodic breathing during incremental cardiopulmonary exercise testing is a
regularly recurring waxing and waning of tidal volume due to oscillations in
central respiratory drive. Periodic breathing is a sign of respiratory control
system instability, which may occur at rest or during exercise. The possible
mechanisms responsible of exertional periodic breathing might be related to any
instability of the ventilatory regulation caused by: 1) increased circulatory
delay (i.e., circulation time from the lung to the brain and chemoreceptors, due
to reduced cardiac index leading to delay in information transfer), 2) increase
in controller gain (i.e., increased central and peripheral chemoreceptor
sensitivity to arterial partial pressure of oxygen and of carbon dioxide), or 3)
reduction in system damping (i.e., baroreflex impairment). Periodic breathing
during exercise is observed in several cardiovascular disease populations, but it
is a particularly frequent phenomenon in heart failure due to systolic
dysfunction. The detection of exertional periodic breathing is linked to outcome
and heralds worst prognosis in heart failure, independently of the criteria
adopted for its definition. In small heart failure cohorts, exertional periodic
breathing has been abolished with more than a few dedicated interventions, but
results have not been confirmed, yet. Accordingly, further studies are needed to
define the role of visceral feed-backs in determining periodic breathing during
exercise, as well as to look for specific tools for preventing/treat its
occurrence in heart failure.

Layton AM, Armstrong HF, Kim HP, Meza KS, D’Ovidio F, Arcasoy SM.

Respir Med. 2017 May;126:59-67. doi: 10.1016/j.rmed.2017.03.022. Epub 2017 Mar
27.

BACKGROUND: The purpose of this work was to determine if parameters assessed
during Cardiopulmonary Exercise Testing (CPET) while using supplemental oxygen
can independently predict one-year transplant-free survival in patients with
Interstitial Lung Disease (ILD) referred for lung transplant evaluation.
METHODS: We performed a chart review of patients with ILD who completed CPET with
30% FiO2 and gathered spirometry, pulmonary hemodynamic, six-minute walk, and
CPET data. The primary end-point was death or lung transplantation within
one-year of CPET.
RESULTS: The final data set included 192 patients. 79 patients died/underwent
transplant, 113 survived transplant-free. Multivariable Cox regression revealed
peak workload % predicted, nadir CPET SpO2, and FVC% predicted as independent
predictors of one-year transplant-free survival. Of the independent predictors of
survival, receiver operating characteristics analysis revealed peak workload
%predicted cutoff of 35% to be highly discriminatory, more so than nadir CPET
SpO2 or FVC % predicted in identifying patients at risk for one-year mortality or
transplant (peak workload % predicted < 35% HR = 4.71, 95% CI = 2.64-8.38 and area under the curve (AUC) = 0.740, nadir CPET SpO2 < 86% HR = 2.27, 95%CI = 1.41-3.68, AUC = 0.645, FVC %predicted <45% HR = 1.82, 95% CI = 1.15-2.87, AUC = 0.624). CONCLUSION: Peak workload % predicted, nadir CPET SpO2, and FVC% predicted in ILD patients referred for lung transplant evaluation are independently predictive of one-year mortality or need for transplant.

Key A; Parry M; West MA; Asher R; Jack S; Duffy N; Torella F; Walker PP;

Liverpool and Southampton

[BMJ Open Respir Res] 2017 Apr 05; Vol. 4 (1), pp. e000164. Date of Electronic Publication: 20170405 (Print Publication: 2017)

Introduction: β Blockers are important treatment for ischaemic heart disease and heart failure; however, there has long been concern about their use in people with chronic obstructive pulmonary disease (COPD) due to fear of symptomatic worsening of breathlessness. Despite growing evidence of safety and efficacy, they remain underused. We examined the effect of β-blockade on lung function, exercise performance and dynamic hyperinflation in a group of vascular surgical patients, a high proportion of who were expected to have COPD.
Methods: People undergoing routine abdominal aortic aneurysm (AAA) surveillance were sequentially recruited from vascular surgery clinic. They completed plethysmographically measured lung function and incremental cardiopulmonary exercise testing with dynamic measurement of inspiratory capacity while taking and not taking β blocker.
Results: 48 participants completed tests while taking and not taking β blockers with 38 completing all assessments successfully. 15 participants (39%) were found to have, predominantly mild and undiagnosed, COPD. People with COPD had airflow obstruction, increased airway resistance (Raw) and specific conductance (sGaw), static hyperinflation and dynamically hyperinflated during exercise. In the whole group, β-blockade led to a small fall in FEV1 (0.1 L/2.8% predicted) but did not affect Raw, sGaw, static or dynamic hyperinflation. No difference in response to β-blockade was seen in those with and without COPD.
Conclusions: In people with AAA, β-blockade has little effect on lung function and dynamic hyperinflation in those with and without COPD. In this population, the prevalence of COPD is high and consideration should be given to case finding with spirometry.

Karenovics W; Licker M; Ellenberger C; Christodoulou M; Diaper J; Bhatia C; Robert J; Bridevaux PO; Triponez F;

University Hospitals of Geneva, Geneva, Switzerland.

[Eur J Cardiothorac Surg] 2017 Apr 17

Objectives: Poor aerobic fitness is a potential modifiable risk factor for long-term survival and quality of life in patients with lung cancer. This randomized trial evaluates the impact of adding rehabilitation (Rehab) with high-intensity interval training (HIIT) before lung cancer surgery to enhance cardiorespiratory fitness and improve long-term postoperative outcome.
Methods: Patients with operable lung cancer were randomly assigned to usual care (UC, n  = 77) or to intervention group (Rehab, n  = 74) that entailed HIIT that was implemented only preoperatively. Cardiopulmonary exercise testing (CPET) and pulmonary functional tests (PFTs) including forced vital capacity (FVC), forced expiratory volume (FEV 1 ) and carbon monoxide transfer factor (KCO) were performed before and 1 year after surgery.
Results: During the preoperative waiting time (median 25 days), Rehab patients participated to a median of 8 HIIT sessions (interquartile [IQ] 25-75%, 7-10). At 1 year follow-up, 91% UC patients and 93% Rehab patients were still alive ( P  = 0.506). Pulmonary functional changes were non-significant and comparable in both groups (FEV 1 mean -7.5%, 95% CI, -3.6 to -12.9 and in KCO mean 5.8% 95% CI 0.8-11.8) Compared with preoperative CPET results, both groups demonstrated similar reduction in peak oxygen uptake (mean -12.2% 95% CI -4.8 to -18.2) and in peak work rate (mean -11.1% 95% CI -4.2 to -17.4).
Conclusions: Short-term preoperative rehabilitation with HIIT does not improve pulmonary function and aerobic capacity measured at 1 year after lung cancer resection.

Vainshelboim B; Rao S; Chan K; Lima RM; Ashley EA; Myers J

Canadian Journal Of Anaesthesia [Can J Anaesth] 2017 Apr 05. Date of Electronic Publication: 2017 Apr 05.

Purpose: The ventilatory threshold (VT) is an objective physiological marker of the capacity of aerobic endurance that has good prognostic applications in preoperative settings. Nevertheless, determining the VT can be challenging due to physiological and methodological issues, especially in evaluating surgical risk. The purpose of the current study was to compare different methods of determining VT and to highlight the implications for assessing perioperative risk.
Methods: Our study entailed analysis of 445 treadmill cardiopulmonary exercise tests from 140 presurgical candidates with an aortic abdominal aneurysm (≥3.0 to ≤5.0 cm) and a mean (standard deviation [SD]) age of 72 (8) yr. We used three methods to determine the VT in 328 comparable tests, namely, self-detected metabolic system (MS), experts’ visual (V) readings, and software using a log-log transformation (LLT) of ventilation vs oxygen uptake. Differences and agreement between the three methods were assessed using analysis of variance (ANOVA), coefficient of variation (CV), typical error limits of agreement (LoA), and interclass correlation coefficients (ICC).
Results: Overall, ANOVA revealed significant differences between the methods [MS = 14.1 (4.3) mLO2·kg-1·min-1; V = 14.6 (4.4) mLO2·kg-1·min-1; and LLT = 12.3 (3.3) mLO2·kg-1·min-1; P < 0.001]. The assessment of agreement between methods provided the following results: ICC = 0.85; 95% confidence interval (CI), 0.82 to 0.87; P < 0.001; typical error, 2.1-2.8 mLO2·kg-1·min-1; and, 95% LoA and CV ranged from 43 to 55% and 15.9 to 19.6%, respectively. Conclusions: The results show clinically significant variations between the methods and underscore the challenges of determining VT for perioperative risk stratification. The findings highlight the importance of meticulous evaluation of VT for predicting surgical outcomes. Future studies should address the prognostic perioperative utility of computed mathematical models combined with an expert's review. This trial was registered at ClinicalTrials.gov, identifier: NCT00349947.