Cardiopulmonary Exercise Testing Suite

One of the major platform technologies of our clinical research program focuses on the use of state-of-the-art cardiopulmonary exercise testing (CPET) technology, a robust and powerful technology that can accurately and reproducibly assess cardiovascular functional capacity. We are at the forefront of efforts to introduce CPET technology into the field of nephrology. The potential exists for CPET indices such as VO2Peak to be used as a new endpoint for cardiovascular trials in nephrology which can help overcome current challenges in cardio-renal trials due to the existing limitations of resting cardiac endpoints. The technology has the potential to help move the cardio-renal field forward.

Founded by Dr. Lim, our CPET laboratory is the first of its kind dedicated to the study of patients with kidney disease in the United States. Our state-of-the-art CPET machine linked to two cycle ergometers for symptom-limited exercise testing dedicated to research in patients with kidney patients. We perform breath-by-breath analysis using a state-of-the-art metabolic cart (VyntusTM CPX Metabolic Cart, Vyaire Medical). Our CPET machine is fully equipped with a non-invasive cardiac output monitor (using signal morphology impedance cardiography, Physioflow). Our cardiac output monitor is synchronized with our metabolic cart at the start of the exercise testing and this enables us to accurately track in real time cardiac changes throughout the exercise testing cycle. Further cardiac monitoring equipment includes 12-lead EKG, cardiac output monitoring, blood pressure and oxygen saturation monitoring system. As part of our CPET set-up, we have both an upright and recumbent bike (the latter which is more user friendly for older patients). 

a participant on the recumbent bike in the cept lab

Equipment

  1. Metabolic cart: computes CPET variables and analyzes obtained data

  2. Graphical display: displays all continuous parameters and gas exchange graphs over time

  3. Digital volume transducer: flow sensor measure breath-by-breath gas exchange

  4. Flexible headgear: elastic headgear fits all head sizes

  5. Pulse oximeter: ear-clip pulse oximeter measure blood oxygen saturation

  6. Blood pressure cuff: systolic and diastolic blood pressure readings are taken in variable intervals

  7. EKG leads: 12-Lead-EKG measure heart rate and rhythm changes

  8. Recumbent cycle ergometer: recumbent cycle fits all patient sizes and accommodates customizable protocols; recumbent modality preferred for CKD population and for intra-CPET assessments

  9. RPM display: patients are to maintain 55-65 rpm for the duration of the test



CPET Modalities

Recumbent Cycle

  • Safest with less weight bearing
  • Compatible with CO and lactate monitoring, NIRS, echo and EVFL

Upright Cycle

  • Best combination of safety and performance
  • Compatible with CO and lactate monitoring, NIRS, echo and EVFL

Treadmill

  • Best approximates daily activity but offers low stability
  • Elicits highest VO2Peak values
  • Generates noise for the intra-CPET tests

 

Patient Interface

Breathing Mask

  • Covers mouth and nose
  • Requires DVT or mixing chamber
  • Greater comfort for individuals

Mouthpiece

  • Requires nose clip
  • Requires DVT or mixing chamber
  • More common for athlete testing

Airflow Analyzers

Digital Volume Transducer

  • Complete breath-by-breath analysis of airflow
  • Sampling rate of 50-100 times per second
  • Airflow volumes averaged by breaths or every 10-30 seconds

Mixing Chamber

  • Expired air is mixed in baffled chamber
  • Fractional O2 and CO2 concentrations averaged every 10-30 seconds
  • Difficult to sterilize

As part of our capability expansion, our CPET laboratory is now equipped with bioimpedance spectroscopy (ImpediMed SFB7) device that enables assessment of fluid status and tissue composition that is FDA approved for clinical and research use. Additionally, in collaboration with Andy Coggan, PhD, (Department of Kinesiology), we have integrated near infrared spectrocoscopy (NIRS) that enables direct assessment of skeletal muscle O2 consumption during CPET. We are also equipped to conduct combined CPET – Transthoracic Echocardiography in collaboration with IU Cardiovascular Services, enabling comprehensive interrogation of cardiovascular functional and structural changes throughout the exercise testing cycle in patients with kidney failure.

Our CPET lab is integrated with the Indiana Center for Musculoskeletal Health Clinical Research Center's FIT core located at IU Health University Hospital. The FIT core is funded by an NIH P30 grant (PI Sharon Moe, MD, director of the Division of Nephrology and Associate Dean of Research at IU School of Medicine). This integration enables all of our research participants to undergo comprehensive basic physical function testing, DEXA and HRpQCT scanning of the limbs as well as opportunities for collaboration, capitalizing on the center’s ongoing imaging, omics technology and informatics projects. Our CPET lab and FIT core is located adjacent to our Clinical Research Center (CRC) that facilitates study flow. Additionally, we have a collaborative partnership with the IU School of Medicine Cardiovascular Institute, Division of Pulmonology, Department of Radiology and Imaging Services and other centers and services enabling us to augment our capabilities and conduct advanced cardiovascular imaging (such as cardiac MRI and CT) and other tests.

a participant in the cept lab