Measurement of breath-by-breath respiration from pacemaker lead impedance data

This trial does not fit neatly into either of the observational or interventional categories. The purpose of this trial is to see whether or not Boston Scientific pacemakers with the ability to measure minute ventilation have accurate enough detection of ventilation to discern each inhalation from each exhalation. To do this, we will apply a respiratory band across each patient's chest. This will serve as the gold standard measurement of inhalation and exhalation, against which the data from the Boston Scientific pacemakers will be compared. To discern whether or not the pacemakers can accurately detect each breath cycle through a range of respiratory rates, we will ask each patient to breathe normally, hold their breath, breathe slowly and breathe rapidly. Will also ask them to swallow water and to laugh to see if these manoeuvres affect the accuracy of inhalation/exhalation detection. We will then ask each patient to walk on a treadmill for 6 minutes to see if motion affects the accuracy of the measurement. We will be observing the signals from the patients' pacemakers but will also be intervening in that we will ask them to perform the aforementioned tasks. There are no intervention/control groups. First, the normal breathing pattern of the patient will be observed for 30 seconds. We will then ask the patient to breathe in sync with the signals coming from an audiovisual metronome. First, the metronome will be set at 20 breaths per minute for 30 seconds. We will then allow the patient a period of rest to recover from the rapid breathing. After that, we will again ask them to synch their breath to the audiovisual metronome signal that is set to 8 breaths per minute for 32 seconds. After another period of recovery, we will ask the patient to hold their breath for 15 seconds. After a period of recovery, we will ask them to drink a cup of water. After that, we will ask them to simulate laughter and/or tell them a joke. Finally, we will ask them to walk at a speed of 5 km/h for 6 minutes. The minute ventilation data from the Boston Scientific pacemaker will undoubtedly include environmental noise that will be interfering with the respiration signal. We will use the pacemaker lead electrogram signal to filter out the noise caused by the pacemaker pacing signal. We will use an electrocardiogram to filter out the noise caused by the electrical activity and contraction of the heart. We will work with bioengineers from the Auckland Bioengineering Institute of Auckland University to develop mathematical methods to filter out the noise from other sources. This will hopefully leave us with filtered data that represents the patient's breathing. Patient's with Boston Scientific pacemakers who are attending pacemaker clinic at Waikato Hospital will be recruited. Measurements for the purpose of this research will be taken after the routine pacemaker check is complete and only when the pacemaker check is considered to be "normal". Experienced clinical cardiac physiology staff who run Waikato Hospital's pacemaker clinics will be present at all times during the data collection sessions to ensure patient safety and to help with the data collection. Each patient who consents will have their measurements recorded once. We estimate that the entire protocol will take 15-20 minutes to complete.