Category Archives: Publications

Scaling the Oxygen Uptake Efficiency Slope for Body Size in Cystic Fibrosis.

Tomlinson OW, Barker AR, Oades PJ, Williams CA

Med Sci Sports Exerc. 2017 Oct;49(10):1980-1986.

PURPOSE: The aim of this study was to describe the relationship between body size
and oxygen uptake efficiency slope (OUES) in pediatric patients with cystic
fibrosis (CF) and healthy controls (CON), 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 used to determine the relationship between body size and 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, and 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).
Nonsignificant (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 OUES between patients with CF and
healthy controls.

Cardiopulmonary exercise testing (CPET) in the United Kingdom-a national survey of the structure, conduct, interpretation and funding.

Perioper Med (Lond). 2018 Jan 26;7:2. doi: 10.1186/s13741-017-0082-3. eCollection
2018.

Reeves T, Bates S, Sharp T, Richardson K,
Bali S, Plumb J, Anderson H, Prentis J, Swart,
Levett DZH; Perioperative Exercise Testing and Training Society
(POETTS).

Background: Cardiopulmonary exercise testing (CPET) is an exercise stress test
with concomitant expired gas analysis that provides an objective, non-invasive
measure of functional capacity under stress. CPET-derived variables predict
postoperative morbidity and mortality after major abdominal and thoracic surgery.
Two previous surveys have reported increasing utilisation of CPET preoperatively
in England. We aimed to evaluate current CPET practice in the UK, to identify who
performs CPET, how it is performed, how the data generated are used and the
funding models.
Methods: All anaesthetic departments in trusts with adult elective surgery in the
UK were contacted by telephone to obtain contacts for their pre-assessment and
CPET service leads. An online survey was sent to all leads between November 2016
and March 2017.
Results: The response rate to the online survey was 73.1% (144/197) with 68.1%
(98/144) reporting an established clinical service and 3.5% (5/144) setting up a
service. Approximately 30,000 tests are performed a year with 93.0% (80/86) using
cycle ergometry. Colorectal surgical patients are the most frequently tested
(89.5%, 77/86). The majority of tests are performed and interpreted by
anaesthetists. There is variability in the methods of interpretation and
reporting of CPET and limited external validation of results.
Conclusions: This survey has identified the continued expansion of perioperative
CPET services in the UK which have doubled since 2011. The vast majority of CPET
tests are performed and reported by anaesthetists. It has highlighted variation
in practice and a lack of standardised reporting implying a need for practice
guidelines and standardised training to ensure high-quality data to inform
perioperative decision making.

Cardiopulmonary fitness is strongly associated with body cell mass and fat-free mass

Köhler A, King R, Bahls M, Groß S, Steveling A, Gärtner S, Schipf S,  Gläser S, Völzke H, Felix SB, Markus MRP, Dörr M

Scandinavian Journal Of Medicine & Science In Sports [Scand J Med Sci Sports] 2018 Jan 18. Date of Electronic Publication: 2018 Jan 18.

Background: Peak oxygen uptake (VO2peak) is commonly indexed by total body weight (TBW) to determine cardiopulmonary fitness (CPF). This approach may lead to misinterpretation, particularly in obese subjects. We investigated the normalization of VO2peak by different body composition markers.
Methods: We analyzed combined data of 3,848 subjects (1,914 women; 49.7%), aged 20-90, from two independent cohorts of the population-based Study of Health in Pomerania (SHIP-2 and SHIP-TREND). VO2peak was assessed by cardiopulmonary exercise testing. Body cell mass (BCM), fat-free mass (FFM) and fat mass (FM) were determined by bioelectrical impedance analysis. The suitability of the different markers as a normalization variable was evaluated by taking into account correlation coefficients (r) and intercept (α-coefficient) values from linear regression models. A combination of high r and low α values was considered as preferable for normalization purposes.
Results: BCM was the best normalization variable for VO2peak (r=0.72; p=<0.001; α-coefficient=63.3 ml/min; 95%confidence interval [CI]: 3.48 to 123) followed by FFM (r=0.63; p=<0.001; α-coefficient=19.6 ml/min; 95%CI: -57.9 to 97.0). On the other hand, a much weaker correlation and a markedly higher intercept were found for TBW (r=0.42; p=<0.001; α-coefficient=579 ml/min; 95%CI: 483 to 675). Likewise, FM was also identified as a poor normalization variable (r=0.10; p=<0.001; α-coefficient=2,133; 95%CI: 2,074 to 2,191). Sex-stratified analyses confirmed the above order for the different normalization variables.
Conclusions: Our results suggest that BCM, followed by FFM, might be the most appropriate marker for the normalization of VO2peak when comparing CPF between subjects with different body shape. This article is protected by copyright. All rights reserved.

Oxygen Uptake Efficiency Slope and Prediction of Post-operative Morbidity and Mortality in Patients with Lung Cancer.

Yakal S, Sofyalı S, Özkan B, Yıldız S, Toker A, Kasikcioglu E
Department of Sports Medicine, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.

Lung [Lung] 2018 Jan 18. Date of Electronic Publication: 2018 Jan 18

Objective: Peak oxygen consumption is a very valuable cardiopulmonary functional parameter in pre-operative evaluation of patients with lung cancer. However, it has several critical limitations for operability decision due to failure in achieving maximal level of exercise test for cases. The aim of this study was to reveal the importance of more accurate cardiopulmonary parameters that can be calculated from data of submaximal level test, such as oxygen uptake efficiency slope (OUES) and to determine whether it could be used in the operability decision phase for borderline cases by means of morbidity and mortality.
Materials and Methods: One hundred and twenty-five patients who were scheduled to undergo lung surgery due to lung cancer were included in the study. Peak oxygen uptake (pVO2), heart rate at the anaerobic threshold, and oxygen consumption volume at anaerobic threshold values were obtained after performing the cardiopulmonary exercise test. The OUES value was calculated from the ratio of the peak VO2 value and logarithmic equivalent of the ventilatory volume (VE). The following equation was used for determining OUES: VO2/log10 VE.
Results: The peak VO2 mean value was 21.37 ± 4.20 mL/min/kg in patients. However, OUES mean value was 12.44 ± 2.11. When the metabolic parameters of the patients were compared, a significant correlation was determined between the peak VO2 value and peak VE, OUES, and survival (p < 0.01).
Conclusion: This study demonstrated that OUES is significantly correlated with peak VO2 and it does not require the performance of maximal exercise and can be used together with peak VO2 in this patient population when there is difficulty in making decision for surgery in patients with lung cancer.

Pre-operative Functional Cardiovascular Reserve Is Associated with Acute Kidney Injury after Intervention

Saratzis A, Shakespeare J, Jones O, Bown MJ, Mahmood A, Imray
CHE
NIHR Leicester Cardiovascular Biomedical Research Unit, University of
Leicester, Leicester, UK. Electronic address: as875@le.ac.uk

Eur J Vasc Endovasc Surg. 2017 May;53(5):717-724. doi:
10.1016/j.ejvs.2017.01.014. Epub 2017 Mar 18.

BACKGROUND: Acute kidney injury (AKI) is a common complication after endovascular
intervention, associated with poor short and long-term outcomes. However, the
mechanisms underlying AKI development remain poorly understood. The impact of
pre-existing cardiovascular disease and low cardiovascular reserve (CVR) in AKI
is unclear; it remains unknown whether AKI is primarily related to pre-existing
comorbidity or to procedural parameters. The association between CVR and AKI
after EVAR was therefore assessed.
METHODS: This is a case control study. From a database of 484 patients, 292
undergoing elective endovascular aneurysm repair (EVAR) of an infrarenal
abdominal aortic aneurysm (AAA) in two tertiary centres were included. Of these,
73 patients who had developed AKI after EVAR were case matched, based on
pre-operative estimated glomerular filtration rate (eGFR; within
5 mL/min/1.73 m2) and age, with patients who had not developed AKI.
Cardiopulmonary exercise testing (CPET) was used to assess CVR using the
anaerobic threshold (AT). Development of AKI was defined using the Kidney Disease
Improving Outcomes (KDIGO) guidance. Associations between CVR (based on AT
levels) and AKI development were then analysed.
RESULTS: Pre-operative AT levels were significantly different between those who
did and did not develop AKI (12.1±2.9 SD vs. 14.8±3.0 mL/min/kg, p < .001). In
multivariate analysis, a higher level of AT (per 1 mL/min/kg) was associated with
a lower odds ratio (OR) of 0.72 (95% CI, 0.63-0.82, p < .001), relative to AKI
development. A pre-operative AT level of < 11 mL/min/kg was associated with
post-operative AKI development in adjusted analysis, with an OR of 7.8 (95% CI,
3.75-16.51, p < .001). The area under the curve (receiver operating
characteristic) for AT as a predictor of post-operative AKI was 0.81 (standard
error, 0.06, 95% CI, 0.69-0.93, p < .001).
CONCLUSIONS: Poor CVR was strongly associated with the development of AKI. This
provides pathophysiological insights into the mechanisms underlying AKI.

Application of Cardiopulmonary Exercise Testing in Enhanced Recovery after Surgery.

Zhang LY, Liu ZJ, Shen L, Huang YG
Department of Anesthesiology,PUMC Hospital,CAMS and PUMC,Beijing 100730,China

Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 2017 Dec 20;39(6):831-835

Enhanced recovery after surgery (ERAS) is a new perioperative concept that aims
to reduce perioperative stress response and accelerate rehabilitation of patients
through a variety of optimized management. With the wider application of this
concept,the effective implementation of ERAS program has become a new challenge.
Cardiopulmonary exercise testing (CPET) has shown promising value in the
preoperative assessment,perioperative optimization,and postoperative
rehabilitation of ERAS. This article reviews the application of CPET in ERAS,with
an attempt to provide evidence for more detailed and comprehensive ERAS program.

Isocapnic buffering phase: a useful indicator of exercise endurance and prognosis in patients with coronary artery disease.

Yen YS, Su DCJ, Yuan KS et al

The Physician And Sportsmedicine [Phys Sportsmed] 2018 Jan 10. Date of Electronic Publication: 2018 Jan 10.

Objectives: The significance of the isocapnic buffering (IB) phase – the period between the first ventilatory threshold (1stVT) and respiratory compensation point (RCP) – has not been adequately established in patients. This study aimed to determine the clinical significance of the IB phase in coronary artery disease (CAD) patients.
Methods: This retrospective study included data of sixty-two CAD patients after coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI) performed in a single medical center between 2010-2014. According to their physical conditions, the patients performed incremental cardiopulmonary exercise test (CPET) using a cycle ergometer by the ramp of 5-20 W/min. Correlations between the corrected IB phase duration and age, body mass index (BMI), left ventricular ejection fraction (LVEF), and CPET parameters were evaluated using Pearson correlation coefficients. Variables predicting peak oxygen consumption (VO2) were evaluated using multiple regression.
Results: Peak VO2 (p < 0.001), VO2 at RCP (p < 0.001), ∆O2/∆WR slope (p < 0.001), maximal partial pressure of end tidal CO2 (PetCO2) (p = 0.0012), VE/VCO2 slope (p = 0.010), BMI (p = 0.012), and age (p = 0.017) were significantly correlated, whereas LVEF (p = 0.246) and VO2 at 1stVT (p = 0.179) were not significantly correlated with the corrected IB phase duration. In multiple regression analysis, the corrected IB phase duration, VO2 at 1stVT, and ∆O2/∆WR slope were significantly associated with peak VO2.
Conclusion: The findings indicate that the IB phase duration is a useful indicator of peripheral cardiopulmonary function, endurance performance, and prognosis in CAD patients.

The Gas Sampling Interval Effect on V˙O2peak Is Independent of Exercise Protocol

Scheadler CM, Garver MJ, Hanson NJ.

Med Sci Sports Exerc. 2017 Sep;49(9):1911-1916

INTRODUCTION: There is a plethora of gas sampling intervals available during
cardiopulmonary exercise testing to measure peak oxygen consumption (V˙O2peak).
Different intervals can lead to altered V˙O2peak. Whether differences are
affected by the exercise protocol or subject sample is not clear. The purpose of
this investigation was to determine whether V˙O2peak differed because of the
manipulation of sampling intervals and whether differences were independent of
the protocol and subject sample.
METHODS: The first subject sample (24 ± 3 yr; V˙O2peak via 15-breath moving
averages: 56.2 ± 6.8 mL·kg·min) completed the Bruce and the self-paced V˙O2max
protocols. The second subject sample (21.9 ± 2.7 yr; V˙O2peak via 15-breath
moving averages: 54.2 ± 8.0 mL·kg·min) completed the Bruce and the modified
Astrand protocols. V˙O2peak was identified using five sampling intervals: 15-s
block averages, 30-s block averages, 15-breath block averages, 15-breath moving
averages, and 30-s block averages aligned to the end of exercise. Differences in
V˙O2peak between intervals were determined using repeated-measures ANOVAs. The
influence of subject sample on the sampling effect was determined using
independent t-tests.
RESULTS: There was a significant main effect of sampling interval on V˙O2peak
(first sample Bruce and self-paced V˙O2max P < 0.001; second sample Bruce and
modified Astrand P < 0.05). The difference in V˙O2peak between sampling intervals
followed a similar pattern for each protocol and subject sample, with 15-breath
moving average presenting the highest V˙O2peak.
CONCLUSIONS: The effect of manipulating gas sampling intervals on V˙O2peak
appears to be protocol and sample independent. These findings highlight our
recommendation that the clinical and scientific community request and report the
sampling interval whenever metabolic data are presented. The standardization of
reporting would assist in the comparison of V˙O2peak.

Comparisons of Noninvasive Methods Used to Assess Exercise Stroke Volume in Heart Failure with Preserved Ejection Fraction

VAN Iterson EH, Olson TP, Borlaug BA, Johnson BD, Snyder EM.

Med Sci Sports Exerc. 2017 Sep;49(9):1758-1768

INTRODUCTION: Cardiopulmonary exercise testing (CPET) plays an important role in
properly phenotyping signs and symptoms of heart failure with preserved ejection
fraction (HFpEF). The prognostic value of CPET is strengthened when accompanied
by cardiac hemodynamic measurements. Although recognized as the “gold” standard,
cardiac catheterization is impractical for routine CPET. Thus, advancing the
scientific/methodologic understanding of noninvasive techniques for exercise
cardiac hemodynamic assessment is clinically impactful in HFpEF. This study
tested the concurrent validity of noninvasive acetylene gas (C2H2) uptake,
echocardiography (ECHO), and oxygen pulse (O2pulse) for measuring/predicting
exercise stroke volume (SV) in HFpEF.
METHODS: Eighteen white HFpEF and 18 age-/sex-matched healthy controls
participated in upright CPET (ages, 69 ± 9 yr vs 63 ± 9 yr). At rest, 20 W, and
peak exercise, SV was measured at steady-state via C2H2 rebreathe (SVACET) and
ECHO (SVECHO), whereas O2pulse was derived (=V˙O2/HR).
RESULTS: Resting relationships between SVACET and SVECHO, SVECHO and O2pulse, or
SVACET and O2pulse were significant in HFpEF (R = 0.30, 0.36, 0.67), but not
controls (R = 0.07, 0.01, 0.09), respectively. Resting relationships persisted to
20 W in HFpEF (R = 0.70, 0.53, 0.70) and controls (R = 0.05, 0.07, 0.21),
respectively. Peak exercise relationships were significant in HFpEF (R = 0.62,
0.24, 0.64), but only for SVACET versus O2pulse in controls (R = 0.07, 0.04,
0.33), respectively. Standardized standard error of estimate between techniques
was strongest in HFpEF at 20 W: SVACET versus SVECHO = 0.57 ± 0.22; SVECHO versus
O2pulse = 0.71 ± 0.28; SVACET versus O2pulse = 0.56 ± 0.22.
CONCLUSIONS: Constituting a clinically impactful step towards construct
validation testing, these data suggest SVACET, SVECHO, and O2pulse demonstrate
moderate-to-strong concurrent validity for measuring/predicting exercise SV in
HFpEF.

Real-Time Analysis of the Heart Rate Variability During Incremental Exercise for the Detection of the Ventilatory Threshold.

Shiraishi Y; Katsumata Y; Sadahiro T; Azuma K; Akita K; Isobe S; Yashima F; Miyamoto K; Nishiyama T; Tamura Y; Kimura T; Nishiyama N; Aizawa Y; Fukuda K; Takatsuki S

Journal Of The American Heart Association [J Am Heart Assoc], ISSN: 2047-9980, 2018 Jan 07; Vol. 7

Background: It has never been possible to immediately evaluate heart rate variability (HRV) during exercise. We aimed to visualize the real-time changes in the power spectrum of HRV during exercise and to investigate its relationship to the ventilatory threshold (VT).
Methods and Results: Thirty healthy subjects (29.1±5.7 years of age) and 35 consecutive patients (59.0±13.2 years of age) with myocardial infarctions underwent cardiopulmonary exercise tests with an RAMP protocol ergometer. The HRV was continuously assessed with power spectral analyses using the maximum entropy method and projected on a screen without delay. During exercise, a significant decrease in the high frequency (HF) was followed by a drastic shift in the power spectrum of the HRV with a periodic augmentation in the low frequency/HF (L/H) and steady low HF. When the HRV threshold (HRVT) was defined as conversion from a predominant high frequency (HF) to a predominant low frequency/HF (L/H), the VO2 at the HRVT (HRVT-VO2) was substantially correlated with the VO2 at the lactate threshold and VT) in the healthy subjects (r=0.853 and 0.921, respectively). The mean difference between each threshold (0.65 mL/kg per minute for lactate threshold and HRVT, 0.53 mL/kg per minute for VT and HRVT) was nonsignificant (P>0.05). Furthermore, the HRVT-VO2 was also correlated with the VT-VO2 in these myocardial infarction patients (r=0.867), and the mean difference was -0.72 mL/kg per minute and was nonsignificant (P>0.05).
Conclusions: A HRV analysis with our method enabled real-time visualization of the changes in the power spectrum during exercise. This can provide additional information for detecting the VT.