Papers by Francesco Rizzo
Ultrasound in Medicine & Biology, 2017
It is known from physiology that heartbeat and respiration influence venous return, but little is... more It is known from physiology that heartbeat and respiration influence venous return, but little is known regarding the extent to which these two factors affect flow. In this study, we estimated the prevalence of cardiacand breathing-induced venous flow modulations in the internal jugular vein (IJV) and vertebral vein (VV) and the effects of posture. In 19 healthy patients, neck vein flow was examined with pulsed wave Doppler. Electrocardiogram and respiratory signals were simultaneously acquired. In supine position, heart contraction always influenced venous flow, whereas breathing influenced 68% of IJV and 34% of VV flow. In sitting position, heart contraction influenced 74% of IJV and 42% of VV flow; breathing influenced 68% of IJV and 61% of VV measures. Thus, cardiac influence is greatly present in supine position, whereas breathing influence prevails in the VV while sitting. This setup allowed us to observe that in some patients, expiration may cause an unexpected increase in venous flow.
The Push-Pull Effect (PPE) is a physiological phenomenon defined as a reduction of +Gz tolerance ... more The Push-Pull Effect (PPE) is a physiological phenomenon defined as a reduction of +Gz tolerance induced by a previous exposure to a -Gz acceleration, that may lead to loss of consciousness. Aim of this study was to evaluate, for the first time, the cardiac rhythm changes associated with PPE during real flights. Data were collected in 3 pilots during flights on the Aermacchi MB- 339-CD aircraft. In each flight, lasting about 60 minutes, ECG, respiration and 3D accelerations were recorded by a new smart garment (the MagIC System). The flight protocol included a maneuver eliciting a reference +5Gz acceleration for 15 seconds (Ref+5G), followed, after a while, by a push-pull maneuver with a profile characterized by a 5-s acceleration at -1Gz (PP-1G) and, with a 1G/s onset, by 15 seconds at +5Gz (PP+5G), so to induce the push-pull gravitational stress. From each ECG recording, a beat-by-beat RR Interval (RRI) series was derived. RRI mean, standard deviation (SDNN) and the RRI Root Mean Square of Successive Difference (RMSSD) were estimated in each pilot during the Ref+5G and the PP+5G maneuvers. As compared with Ref+5G, all pilots displayed significant reductions in RRI mean, SDNN and RMSSD during PP+5G. These findings are compatible with a PP-induced enhancement in the sympathetic drive to the heart -as shown by the reduction in RRI mean and SDNN- and a concomitant deactivation of the parasympathetic control as shown by the reduction in RMSSD.
Seismocardiogram (SCG) is the recording of the minute body accelerations induced by the heart act... more Seismocardiogram (SCG) is the recording of the minute body accelerations induced by the heart activity, and reflects mechanical aspects of heart contraction and blood ejection. So far, most of the available systems for the SCG assessment are designed to be used in a laboratory or in controlled behavioral and environmental conditions. In this paper we propose a modified version of a textile-based wearable device for the unobtrusive recording of ECG, respiration and accelerometric data (the MagIC system), to assess the 3d sternal SCG in daily life. SCG is characterized by an extremely low magnitude of the accelerations (in the order of g × 10(-3)), and is masked by major body accelerations induced by locomotion. Thus in daily life recordings, SCG can be measured whenever the subject is still. We observed that about 30 seconds of motionless behavior are sufficient for a stable estimate of the average SCG waveform, independently from the subject's posture. Since it is likely that during spontaneous behavior the subject may stay still for at least 30 seconds several times in a day, it is expected that the SCG could be repeatedly estimated and tracked over time through a prolonged data recording. These observations represent the first testing of the system in the assessment of SCG out of a laboratory environment, and open the possibility to perform SCG studies in a wide range of everyday conditions without interfering with the subject's activity tasks.
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
Seismocardiogram, SCG, can be detected over the 24 hours in ambulant subjects by a textile-based ... more Seismocardiogram, SCG, can be detected over the 24 hours in ambulant subjects by a textile-based wearable system together with the electrocardiogram, ECG and respiration. In this pilot study we explored the possibility to derive 24 h profiles of cardiac time intervals, i.e. indexes of heart mechanical function, from the SCG recordings performed in daily life conditions by the above wearable system. Two healthy subjects were recruited for the study. They worn the system for 24 hours during a working day. From each recording, every 30 minutes the following parameters were derived from the ECG and SCG signals: RR interval, RRI, Pre-Ejection Period, PEP, Isovolumic Contraction Time, ICT, Left Ventricular Ejection Time, LVET, Isovolumic Relaxation Time, IRT. From the analysis it appears that 1) all parameters are characterized by a coefficient of variation in the same order of magnitude, and 2) 24 h LVET time profiles mirrors the long term RRI behavior. Common trends in PEP and ICT profiles were observed in one subject. This study indicates that indexes of cardiac mechanics can be derived from SCG recordings performed over the 24 hours. The obtained positive results encourage further studies to refine this methodology and confirm the present findings.
IEEE Transactions on Information Technology in Biomedicine, 2010
This paper illustrates two extensive applications of a smart garment we previously developed for ... more This paper illustrates two extensive applications of a smart garment we previously developed for the monitoring of ECG, respiration, and movement. In the first application, the device, named Maglietta Interattiva Computerizzata (MagIC), was used for the home monitoring of cardiac patients. The used platform included MagIC for signals collection, a touchscreen computer with a dedicated software for data handling, and a universal mobile telecommunications system (UMTS) dongle for data transmission, via email, to three cardiologists. Three patients daily-performed 3-min telemonitoring sessions for 30 days by using the platform. The whole system behaved correctly in 85 out of 90 sessions. In five instances, a second session was required due to UMTS traffic congestion. Only in three sessions, cardiologists asked the patient to repeat the acquisition because of poor signal quality. In the second application, MagIC was used to evaluate the effects of high-altitude hypoxia on sleep and 24 h daily life in 30 healthy subjects at 3500 and 5400 m above sea level on Mount Everest slopes. The use of MagIC garment was reported to be simple and requiring short instrumentation time even in the demanding expedition environment. The signal quality was adequate in 111 out of 115 recordings and 90% of the subjects found the vest comfortable.
Extreme environments such as high altitude represent a challenging testbed for both people and in... more Extreme environments such as high altitude represent a challenging testbed for both people and instruments. During a recent expedition to the slopes of Mt. Everest, (Highcare Expedition), we monitored ECG, respiration, oxygen saturation and posture in five climbers during sleep. Data were collected by using a recently developed textile-based wearable system (the MagIC system). The polysomnographic acquisitions were performed at sea level in indoor environment, and at 6000 and 6800 m asl in tents. The collected data allowed us to investigate performances and usability of MagIC system as a polysomnographic device at very-high altitude. In this paper we report on the results of this evaluation.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2005
The paper presents a new textile-based wearable system for the unobtrusive recording of cardiores... more The paper presents a new textile-based wearable system for the unobtrusive recording of cardiorespiratory and motion signals during spontaneous behavior along with the first results concerning the application of this device in daily life and in a clinical environment. The system, called MagIC (Maglietta Interattiva Computerizzata), is composed of a vest, including textile sensors for detecting ECG and respiratory activity, and a portable electronic board for motion detection, signal preprocessing and wireless data transmission to a remote monitoring station. The MagIC system has been tested in freely moving subjects at work, at home, while driving and cycling and in microgravity condition during a parabolic flight. Applicability of the system in cardiac in-patients is now under evaluation. Preliminary data derived from recordings performed on patients in bed and during physical exercise showed 1) good signal quality over most of the monitoring periods, 2) a correct identification of...
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Papers by Francesco Rizzo