Paolo Marchionni

An optical measurement method for the simultaneous assessment of respiration and heart rates in preterm infants

Many conventional medical monitoring devices, while not technically invasive, are nevertheless obtrusive insofar as they require contact with the patient. This obtrusiveness sometimes poses problems in daily clinical practice. The need for contact with electrodes or transducers is particularly relevant in the case of patients recovering in intensive care units where continuous monitoring is required, in turn requiring continuous direct transducer contact for prolonged periods. Among the many physiological parameters commonly acquired, the respiratory and the cardiac rates of the patients are of primary importance. Typically these two parameters are measured respectively using spirometry and electrocardiography (ECG), both involving obtrusive measurement systems requiring contact with the patient with an air conduit and electrodes. This paper presents an optical measurement method for the simultaneous assessment of respiration and heart rates based on the measurement of the chest wall movements, associated with inspiratory/expiratory activities of the lungs and by the mechanical pumping action of the heart. The measurement method has been adapted for use with preterm infants and it has been applied to 55 patients recovering in a Neonatal Intensive Care Unit. The method is based on the use of a laser Doppler vibrometer (LDVi) pointed at the left, ventral thoracic surface of the patient. LDVi-based measures of respiration and heart rate have been simultaneously acquired for each patient, in parallel with the same quantities acquired using conventional reference instrumentation (flow-meter and ECG) for comparison purposes. Results show that for respiration rate, differences with respect to the spirometer data are <3%, while for the cardiac rate they are <6% with respect to ECG data. The method proposed in this paper has the advantage of requiring no contact with the patient. Moreover, it supports, by means of a single instrument, the simultaneous measurement of respiration and heart rates, thus reducing the burden of the number of electrodes, transducers, and other instrumentation that must be applied to the patient--a consideration that is particularly important in the Neonatal Intensive Care Unit. In addition to the measurement of respiration rate, we also describe the sensitivity of the LDVi method in detecting key respiration events (irregular inspiration/expiration cycles, apneas, and hiccups) which are relevant to clinical monitoring.

Heart rate measurement in neonatal patients using a webcamera

At present there is a clear need for non-contact monitoring of the physiological signs of the patients. The system proposed in this paper aims to measure the heart rate of neonatal infants without any direct contact with the patient. The solution proposed is based on the use of standard, low-cost and commercially available digital webcamera by which it has been possible to observe defined portions of the patient face; the sequence of such images has then been used, by a specifically developed algorithm (based on Indipendent Component Analysis), to extract the heart rate of the patients. Data collected on 7 patients demonstrate the feasibility of the measurement method proposed. Data acquired on the same patients with standard electrocardiography (ECG) has been used for comparison. Bland-Altman analysis of data show close correlation of the heart rates measured with the two approaches (correlation coefficient of 0.94) with an uncertainty of 4.5 bpm (k=1). This technique has a valuable interest for the use in clinical environment as non-contact, easily deployable and economic monitoring system, but it also shows an interesting potential for remote, home health monitoring.

Non contact measurement of heart and respiration rates based on Kinect

Heart Rate (HR) and Respiration Rate (RR) are considered among the most useful biomedical signals to be observed from a subject in order to evaluate his/her health conditions. HR and RR are routinely monitored in patients recovered in hospitals and eventual variations of these quantities need to be measured and reported. Today HR and RR are measured with standard methods: electrocardiography (ECG) and spirometry (SP). Both this methods need to be in contact with the subject and require the presence of expert personnel to be correctly operated. Consequently, their use is limited to hospitals or ambulatory environments and their diffusion in domestic environments is rare. In this paper we present a novel method for the measurement of HR and RR without contact on a subject. The proposed method is realized by means of a Kinect™ Device (KD). The KD is a widely-diffused multi-sensors device based on a depth-sensor, a camera-sensor and 4 microphones. In our work it has been used in conjunction with a special processing algorithm to calculate the HR and RR values. In order to measure HP and RR 10 healthy subjects were observed with the proposed method and with reference methods (ECG and a SP). Results from tests show that the standard deviation of the residuals (difference between the ECG or SP data and the corresponding measurements obtained by KD) are 6% and 9.7% for HR and RR values respectively. Therefore the proposed measurement method, based on the use of KD, could be used for the home-monitoring of HR and RR values in healthy subject without the presence of experts or clinicians.

Optical method for measurement of respiration rate

Standard instrumentation for the assessment of the respiration rate is largely used in medicine. Spirometers, textile-based capacitive sensors or photopletismography are all contact devices used for such aim; the main drawback in their use is the necessity to have a direct contact between the instrument and the patient, which in some cases can limit the use of such devices. In this paper, we present an optical, fully no-contact measurement method for monitoring of the respiration rate, based on the assessment of chest wall movements (velocity and displacement) by a laser Doppler vibrometer (LDVi). The proposed method is operated at a distance of 1.5 m, on different point of the patient thoracic and abdominal area. The measurement procedure was already demonstrated to precisely perform for what concern the monitoring of the cardiac activity. In this paper, we have monitored 33 patients with a reference instrument (spirometer) and with the proposed non-contact method. Statistical analysis (Bland-Altman) of the respiration rate measured with both instruments is reported. We also report a study on the optimal position on the thoracic area based on quality of the signal measured on the same population of subject. Results demonstrate the possibility to continuously monitor the respiration rate with a mean difference respect to the spirometer data of 13 m ( relative error: 0.35%).

A non-contact optical procedure for precise measurement of respiration rate and flow

The use of standard instrumentation for the assessment of the respiration rate as of flow is an important goal in medicine. Spirometers, textile-based capacitive sensors or photopletismography are standard contact instrumentations used for such aim; the main drawback in the use of such instrumentations is the necessity to have a direct contact of the instrument with the patient. In this paper, we present an optical no-contact method for monitoring of both the respiration rate and flow. This method is based on the measurement of external chest wall movement by a laser Doppler vibrometer. The measurement procedure has already been demonstrated to be extremely well performing for what concern the monitoring of the cardiac activity. The proposed method can be operated at a distance of 1.5 m, on different point of the patient thoracic and abdominal area. We have monitored respiration rate and flow on 8 patients with a spirometer and simultaneously with the proposed noncontact measurement procedure. Bland-Altman analysis of the respiration rate measured with both instruments demonstrate a mean error on the determination of the respiration rate of < 1% and of the < 4% for the instantaneous flow. We also report a study on the optimal position on the thoracic area based on quality of the signal measured on the same population of subject.

Laser doppler myography (LDMi): A novel non-contact measurement method for the muscle activity

BACKGROUND AND AIMS Electromyography (EMG) is considered the gold-standard for the evaluation of muscle activity. Transversal and dimensional changes of the muscle, during muscle activity, generate vibrational phenomena which can be measured by Laser Doppler Vibrometry (LDVi). There is a relationship between muscle contraction and vibrational activity, therefore, some information on fundamental muscle parameters can be assessed without contact with LDVi. In this paper, we explore the possibility to relate the EMG signal causing the muscle contraction and the vibrational activity also measureable on the muscle. A novel non-contact measurement method - Laser Doppler myography (LDMi) - aiming to measure the vibrational behavior of muscle during contraction, is presented herein. Correlations with some parameters normally measured with EMG are reported. MATERIALS AND METHODS The proposed method has been compared with standard superficial EMG (sEMG). Signals produced with sEMG and laser Doppler myography have been simultaneously acquired and processed to test correlations on a population of 20 healthy volunteers. Tests have been carried out on the flexor carpi ulnaris and the tibialis anterior muscles (left and right). RESULTS RESULTS show that it is possible to measure: The timing of muscle activation (max differences: 440 ms), the amplitude of the signals acquired during activation respect to the signals during rest (S/N), the correlation between the S/N of the sEMG and LDMi signals at different levels of force (P> 0.89), and to assess muscle fatigue. CONCLUSIONS LDMi is a valid measurement technique for the assessment of muscle activity and fatigue. It is a non-contact method and this characteristic could suggest its use together with low level laser therapy pre-, intra- and post-LLLT sessions to evaluate the efficacy and effects of the treatments without the need for invasive electrodes.

Muscle activity characterization by laser Doppler Myography

Electromiography (EMG) is the gold-standard technique used for the evaluation of muscle activity. This technique is used in biomechanics, sport medicine, neurology and rehabilitation therapy and it provides the electrical activity produced by skeletal muscles. Among the parameters measured with EMG, two very important quantities are: signal amplitude and duration of muscle contraction, muscle fatigue and maximum muscle power. Recently, a new measurement procedure, named Laser Doppler Myography (LDMi), for the non contact assessment of muscle activity has been proposed to measure the vibro-mechanical behaviour of the muscle. The aim of this study is to present the LDMi technique and to evaluate its capacity to measure some characteristic features proper of the muscle. In this paper LDMi is compared with standard superficial EMG (sEMG) requiring the application of sensors on the skin of each patient. sEMG and LDMi signals have been simultaneously acquired and processed to test correlations. Three parameters has been analyzed to compare these techniques: Muscle activation timing, signal amplitude and muscle fatigue. LDMi appears to be a reliable and promising measurement technique allowing the measurements without contact with the patient skin.

A wearable multipoint ultrasonic travel aids for visually impaired

In 2010, the World Health Organization estimates that there were about 285 million people in the world with disabling eyesight loss (246 millions are visually impaired (VI) and 39 millions are totally blind). For such users, hits during mobility tasks are the reason of major concerns and can reduce the quality of their life. The white cane is the primary device used by the majority of blind or VI users to explore and possibly avoid obstacles; it can monitor only the ground (< 1m) and it does not provide protection for the legs, the trunk and the head. In this paper, authors propose a novel stand-alone Electronic Travel Aid (ETA) device for obstacle detection based on multi- sensing (by 4 ultrasonic transducers) and a microcontroller. Portability, simplicity, reduced dimensions and cost are among the major pros of the reported system, which can detect and localize (angular position and distance from the user) obstacles eventually present in the volume in front of him and on the ground in front of him.

Simultaneous measurement of respiration and cardiac period in preterm infants by laser Doppler vibrometry

The paper presents an optical non-contact method for simultaneous measurement of the heart beat and respiration period, based on the assessment of the chest wall movements induced by the pumping action of the heart, and by inspiration/expiration acts of the lungs. The measurement method is applied on 40 patients recovered in a Neonatal Intensive Care Unit (NICU), where the operating conditions are often critical and the contact with the patient’s skin needs to be minimized. The method proposed is based on optical recording of the movements of chest wall by means of a laser Doppler vibrometer directly pointed onto the left, frontal part of the thoracic surface. Data measured were compared with reference instrumentation; to reach this goal, the ECG and Laser Doppler Vibrometer (LDV) signals were simultaneously acquired to monitor the heart period (HP), while to measure respiration period (RP) signals from a spirometer and a LDV were collected simultaneously. After LDV signals decomposition, heart and respiration acts were detected and compared in term of beat per minute (bpm). HPs measured by the proposed method showed an uncertainty <6% (respect to ECG), while for RPs data an uncertainty of 3% (respect to spirometer data) was estimated. The proposed method has the intrinsic advantage to be totally without contact and to allow the simultaneous measurement of heart and respiration rate also in critical, clinical environments such as the NICU.The paper presents an optical non-contact method for simultaneous measurement of the heart beat and respiration period, based on the assessment of the chest wall movements induced by the pumping action of the heart, and by inspiration/expiration acts of the lungs. The measurement method is applied on 40 patients recovered in a Neonatal Intensive Care Unit (NICU), where the operating conditions are often critical and the contact with the patient’s skin needs to be minimized. The method proposed is based on optical recording of the movements of chest wall by means of a laser Doppler vibrometer directly pointed onto the left, frontal part of the thoracic surface. Data measured were compared with reference instrumentation; to reach this goal, the ECG and Laser Doppler Vibrometer (LDV) signals were simultaneously acquired to monitor the heart period (HP), while to measure respiration period (RP) signals from a spirometer and a LDV were collected simultaneously. After LDV signals decomposition, heart and respir...

A measurement procedure for the assessment of thermoregulatory activitity in premature babies

Many important vital signs need to be measured on preterm patients when they are recovered in intensive care units: cardiac rate, respiration activity, blood saturation, temperature. The later is, in particular, a key quantity to assess when the aim is to verify if the patient has fully developed the capacity to regulate his/her temperature. Presently, the procedure followed by clinicians is based on a subjective test, which sees the heating system of the curl switched off; if the central temperature of the patient will not be reduced below 35°C in the following two hours, the patient is considered able to thermoregulate himself. The aim of this paper is to propose a measurement procedure aiming to verify if the patient has the ability to autonomously thermoregulate. The procedure is based on the use of a multipoint (up to 16 sensing points), measurement system of the superficial temperature, that can assess the patient temperature (on 6 sites) and the surrounding temperature (inside and outside the crib), while the heating system is switched off. In this paper, 48 premature patients (mean gestation age 34 week and mean weight 1791 g) have been tested. Results demonstrate that from the measured data, it is possible to correctly identify patients with an adequate thermoregulation capacity (sensitivity of 0.81 and specificity of 0.89) and with a rapid procedure (<; 5 min).