CORRELATION BETWEEN INITIAL CLAUDICATION TIME, ABSOLUTE CLAUDICATION TIME, AND MUSCLE OXYGEN RECOVERY TIME
Advisor Information
Dr. Sara Myers
Presentation Type
Poster
Start Date
1-3-2019 10:45 AM
End Date
1-3-2019 12:00 PM
Abstract
INTRODUCTION
Peripheral Artery Disease (PAD) is a cardiovascular disease caused by blockages of the leg arteries that reduce blood flow. Claudication, a cramping pain or tiredness in the ischemic legs, is the most prevalent symptom of PAD and impairs patient walking ability [1]. Oxygen delivery in the leg muscles is likely an important determinant of claudication and functional problems in these patients. The time of claudication pain onset and the time at which claudication pain forces the patients to stop walking are known as initial claudication time (ICT) and absolute claudication time (ACT) respectively. Previous studies have shown that health-related quality of life assessments are positively correlated with absolute claudication times [2, 3]. The purpose of this study was to identify if there is any relationship between claudication times and time to recovery of baseline muscle oxygen levels.
METHODS
Eleven male subjects with PAD (age: 68.91 ± 7.45 years, BMI: 32.59 ± 7.98 kg/m2) were recruited through the clinics at the Nebraska-Western Iowa Veterans Affairs Medical Center. All subjects possessed an ankle brachial index < 0.90 as a precondition for PAD. The PortaMon (Artinis Medical System) is a muscle oxygen monitor that uses near infrared spectroscopy to measure the muscle oxygen saturation. This monitor was attached to the gastrocnemius muscle for all subjects. The subjects began the trial with a seated rest for 3 minutes to obtain a baseline. Then subjects performed a standardized graded treadmill test; a protocol speed of 0.89 m/s (2.0 mph) that began at 0% grade and increased 2% grade every two minutes. The subjects verbally reported the onset of claudication pain during the testing and the corresponding times were recorded as ICT. The subjects continued to walk until claudication pain forced to stop, which was recorded as ACT. The subjects were then placed into seated rest to monitor their muscle oxygen recovery. The recovery time was defined as the point at which muscle oxygen saturation levels reached a plateau. A Pearson’s correlation was performed between the claudication times (ICT and ACT) and recovery time.
RESULTS AND DISCUSSION
There were no significant relationships between the claudication times and recovery time. The coefficient of determination was R2=0.1526 for ICT and recovery time, and R2=0.2371 for ACT and recovery time (Figure 1). Both sets of data provide little support that variability in recovery time is caused by variations in claudication times.
The current study includes only eleven patients and does not represent the entire PAD population. Including large number of patients will increase the statistical power of the study. Lack of correlation between claudication and recovery times indicate blood flow and oxygen delivery are not the only factors that determine how far patients with PAD can walk.
CONCLUSIONS
Our results suggest that there is no significant relationship exists between the claudication times and recovery time. Future studies should include more patients with several intervention methods to better understand their contributions in claudication distances, claudication times and recovery times in patients with PAD.
CORRELATION BETWEEN INITIAL CLAUDICATION TIME, ABSOLUTE CLAUDICATION TIME, AND MUSCLE OXYGEN RECOVERY TIME
INTRODUCTION
Peripheral Artery Disease (PAD) is a cardiovascular disease caused by blockages of the leg arteries that reduce blood flow. Claudication, a cramping pain or tiredness in the ischemic legs, is the most prevalent symptom of PAD and impairs patient walking ability [1]. Oxygen delivery in the leg muscles is likely an important determinant of claudication and functional problems in these patients. The time of claudication pain onset and the time at which claudication pain forces the patients to stop walking are known as initial claudication time (ICT) and absolute claudication time (ACT) respectively. Previous studies have shown that health-related quality of life assessments are positively correlated with absolute claudication times [2, 3]. The purpose of this study was to identify if there is any relationship between claudication times and time to recovery of baseline muscle oxygen levels.
METHODS
Eleven male subjects with PAD (age: 68.91 ± 7.45 years, BMI: 32.59 ± 7.98 kg/m2) were recruited through the clinics at the Nebraska-Western Iowa Veterans Affairs Medical Center. All subjects possessed an ankle brachial index < 0.90 as a precondition for PAD. The PortaMon (Artinis Medical System) is a muscle oxygen monitor that uses near infrared spectroscopy to measure the muscle oxygen saturation. This monitor was attached to the gastrocnemius muscle for all subjects. The subjects began the trial with a seated rest for 3 minutes to obtain a baseline. Then subjects performed a standardized graded treadmill test; a protocol speed of 0.89 m/s (2.0 mph) that began at 0% grade and increased 2% grade every two minutes. The subjects verbally reported the onset of claudication pain during the testing and the corresponding times were recorded as ICT. The subjects continued to walk until claudication pain forced to stop, which was recorded as ACT. The subjects were then placed into seated rest to monitor their muscle oxygen recovery. The recovery time was defined as the point at which muscle oxygen saturation levels reached a plateau. A Pearson’s correlation was performed between the claudication times (ICT and ACT) and recovery time.
RESULTS AND DISCUSSION
There were no significant relationships between the claudication times and recovery time. The coefficient of determination was R2=0.1526 for ICT and recovery time, and R2=0.2371 for ACT and recovery time (Figure 1). Both sets of data provide little support that variability in recovery time is caused by variations in claudication times.
The current study includes only eleven patients and does not represent the entire PAD population. Including large number of patients will increase the statistical power of the study. Lack of correlation between claudication and recovery times indicate blood flow and oxygen delivery are not the only factors that determine how far patients with PAD can walk.
CONCLUSIONS
Our results suggest that there is no significant relationship exists between the claudication times and recovery time. Future studies should include more patients with several intervention methods to better understand their contributions in claudication distances, claudication times and recovery times in patients with PAD.