CleveMed Blogs

On New Years Eve 2009, Travis Pastrana found himself sitting in a rally car, mentally preparing to jump 269 feet across a body of water to break the world record for longest rally car jump. His instructions were clear: begin on the Pine Street Pier in Long Beach, California, take off on a ramp, fly approximately 50 feet above the water, and successfully land on a floating barge about 300 feet away. In the event of failure, he had a scuba tank, as well as rescue crews on the water.

CleveMed had the opportunity to use the BioRadio and BioCapture software to collect physiological data, as well as the car’s acceleration relative to free-fall, during Pastrana’s practice runs. Electrocardiogram (ECG) electrodes and a respiratory effort belt were attached to Pastrana, and the BioRadio was set up to measure G-forces in the car and characteristics such as heart rate and breathing rate were derived. The BioRadio monitored Pastrana’s entire jump, and physiological data collected provided fascinating information about the physiological response Pastrana experienced related to performing such a dangerous and adrenaline-filled stunt.

So, here’s the physiology of Travis Pastrana’s 269-foot jump:

As Pastrana sat waiting to accelerate forward his heart rate was elevated at approximately 107 beats per minute (bpm). His breathing patterns were relatively normal at this time, but his respiratory rate was also elevated.

As Pastrana began his approach, heart rate increased to 110 bpm. Additionally, right as he began to accelerate he took a very deep breath. After this initial breath Pastrana’s breathing was very shallow and rapid.

Upon reaching the end of the ramp where the rally car began its flight, Pastrana’s heart rate was 122 bpm. In addition, at the moment the car reached the edge of the ramp, Pastrana held his breath, and continued to hold it the entire time in the air. During this mid-air flight, Pastrana’s heart rate was approximately 130 bpm.

When the rally car landed on the opposite ramp, Pastrana exhaled deeply, and was quickly followed by a deep inhale and gradually slower respiration rates. In addition, when his rally car made impact with the ramp, Pastrana’s heart rate was 138 beats per minute. Once the car began decelerating, his heart rate gradually decreased until reaching the average normal resting heart rate. This physiological data is significant because it provides insight into the body’s reaction to extreme stress.

But other explanations for Pastrana’s physiological response could be attributed to the physical forces he experienced during his rally car’s flight. It was seen that as Pastrana began accelerating, his car was under approximately 1G of force, and at take-off it was as high as 5G’s. You can read about it here, from “The Physiology of a 269-foot Jump” as seen in BioRadio Research & Education Quarterly, Summer 2010. You can also see a screen-shot of Pastrana’s physiological data collected by BioRadio here!

In conclusion, BioRadio provided a clear image of the physiological response of an extreme sportsman. Even though Pastrana has been performing dangerous stunts for over a decade, it is evident that he still experiences stress and probably excitement during his jaw dropping stunts!

Last week, I wrote about the new GSR sensor that will expand BioRadio’s applications, and now it’s time to discuss, yet another new accessory that CleveMed is offering for the BioRadio: the skin temperature sensor.

In 1833 Michael Faraday noticed the resistance of silver sulfide decreased dramatically as temperature increased. This was the first documented observation of a compound that could be used as a thermistor. However, thermistors were difficult to produce and therefore commercial production did not begin until the 1930s with the technology vastly improving since then. The second new accessory integrated into the BioRadio is a skin/surface probe that can detect temperatures in the range of 70°F through 110°F. This probe, which is a thermistor, derives measurements based on a resistor whose resistance varies with changing temperature.

Thermistors can be used in a variety of applications relating to skin temperature measurements. First, it could be used to monitor dangerous physiological reactions, such as heat stroke in applications such as athletics and emergency workers. Next, thermistors could be used in a research setting involving the skin temperature of first responders, such as firefighters. If a new or improved material is developed for safety gear, the thermistor could be used to demonstrate the gear’s efficacy at shielding firefighters from heat. Similarly, thermistors could be used in the military to examine potential safety gear for personnel who are fighting in a war. Thermistors could also be used in sports medicine measurements, such as exploring the body’s ability to thermoregulate while performing a variety of strenuous activities for an extended period of time. Additionally, similar strategic experimental sensor placements could be executed in order to determine if and how certain behaviors, experiences, and actions affect body temperature. Such findings could provide a deeper understanding of mental and physiological processes that could ultimately be used for a variety of therapeutic and pharmacological interventions.

This post is an adaptation from “New GSR & Skin Temp Sensors Expand BioRadio Applications” as seen in BioRadio Research & Education Quarterly, Summer 2010.

CleveMed will soon be offering two new accessories for the BioRadio — galvanic skin response (GSR) and skin temperature sensors. These accessories further expand the possibilities of the BioRadio for research and educational applications. Ranging from psychology-related fields, in exploring connections between behavior and emotion, to sports medicine fields, in exploring the correlations between exercise and physiological response, these new accessories can provide valuable information for a broad range of applications. (This week, I will be writing about the new GSR sensor, and we’ll discuss the skin temperature sensor next week.)

In ancient China, a suspect would hold rice in the mouth during a prosecutor’s speech. If at the end the suspect could not successfully spit out all the rice, they were considered guilty. It was believed a lack of salivation was attributed to anxiety and therefore guilt. With today’s technology, there is no need for rice! Biomedical sensors can measure skin conductivity from the fingers and/or palms to provide a modern mechanism to measure emotions. The GSR sensor is highly sensitive to emotions in some people and can be used as a polygraph, or lie detector test. GSR has also been used as an index for those who need some measurable parameter of a person’s internal “state”. Physiologically, GSR quantifies sweat gland activity and changes in the sympathetic nervous system. Measured from the palm or fingertips, there are changes in relative conductance of a small electrical current between the electrodes. The activity of sweat glands in response to sympathetic nervous stimulation (increased sympathetic activation) results in an increase in conductance. There is a relationship between sympathetic activity and emotional arousal, although one cannot identify the specific emotion being elicited. Fear, anger, startle response, orienting response and sexual feelings are all among emotions which may produce similar GSR responses. This new accessory offers research labs and schools a new interface to use to provide insightful information about emotional response in a variety of applications.

This post is an adaptation from “New GSR & Skin Temp Sensors Expand BioRadio Applications” as seen in BioRadio Research & Education Quarterly, Summer 2010.

Oil spills have a catastrophic effect on marine wildlife, and a controversial effect on human health. Recently, it has been determined that leaking oil is about 40% methane gas, compared to 5% found in typical oil deposits. Such high levels of methane can suffocate marine life and create “dead zones” where oxygen is so depleted nothing in those areas can survive. While humans do not face nearly the same exposure risk as animals, the most common oil exposure mechanism is inhalation of oil-related fumes. In addition, fumes of chemical dispersants often used to contain the spill, as well as the risk of inhaling the methane gas, may be hazardous. Exposure to high levels of methane gas depletes oxygen levels, causing difficulty breathing and leading to suffocation if left untreated. Nausea, vomiting, dizziness, headache, and heart palpitations are also symptoms of methane gas poisoning. In addition to inhalation exposure, people also face the potential of ingesting contaminated food products, as well as physical contact if walking or swimming along a contaminated beach. The effect of oil exposure in humans is not entirely known, but recently the Centers for Disease Control (CDC) have noticed some complaints of throat irritation, eye irritation, nausea, headache, and cough in Gulf area residents, all of which could be attributed to a variety of causes. So far, about 60 exposure-related complaints have been filed with the Louisiana Department of Health and Hospitals by individuals who are working to clean up the spill.

While containment and oil clean up is critical, there is also a need for health clean up, where biomedical engineering can play an important role. Bioinstrumentation can be critical in addressing health concerns for animals and humans. Since air exposure is the most common way humans may be affected, monitoring blood oxygen levels, lung capacity, and breathing patterns can determine respiratory effects. Furthermore, monitoring cardiac characteristics could demonstrate methane poisoning based on presence of a heart beating rapidly, abnormally, and any arrhythmias. Additionally, examining electrical characteristics of the heart could determine if any symptoms, such as shortness of breath, are a result of cardiac conduction problems. Bioinstrumentation allows researchers and medical personnel to collect physiological data to determine when these types of symptoms are occurring and differentiate underlying causes as well as the potential need for immediate medical treatment. The proper bioinstrumentation tools such as wireless physiological monitors are crucial in situations such as an oil spill because they can rapidly provide health information necessary for treating exposure related illnesses.

Typically, bioinstrumentation is large and bulky, often mounted on carts, and tethered to a wall power supply. These systems are extremely limited because of their inability for use in remote or rugged locations. Remote and compact bioinstrumentation can have significant benefits in situations such as the Gulf oil spill. CleveMed’s BioRadio could be used to research physiological effects on individuals who are working with oil spill clean up without hindering the effort. It could also be used to explore whether or not individuals working directly with the oil (for instance, scooping tar balls out of the water) have different physiological characteristics than those working indirectly with the oil, such as washing off animals, and provide insight as to whether or not certain cleaning locations are more dangerous than others. Such data could be used to try to develop a theoretical “map” of the breadth of spill-related fumes and their effect on a variety of populations. The BioRadio is a wireless, 12-channel, lightweight, programmable physiological monitor for viewing and recording any combination of physiological signals, such as ECG, EEG, EOG and EMG, respiration, spirometry, oximetry and more. The BioRadio has a transmission range of approximately 100 feet and battery life up to 12 hours continuous.

This post is an adaptation from “Can Biomedical Engineering Clean Gulf Oil Spill Effects?” as seen in BioRadio Research & Education Quarterly, Summer 2010.