Pulse oximetry of body cavities and organs

The focus of this paper will be in the development and in vivo applications of new custom made photoplethysmographic (PPG) and pulse oximetry optical and fiber optic sensors and instrumentation in an effort to investigate their suitability in the estimation of blood oxygen saturation and their contribution in the assessment of organ/tissue perfusion and viability. The paper describes the development of optical and fiber optic PPG and blood oxygen saturation (SpO2) sensors and covers examples of application areas including real-time PPG monitoring from body cavities (esophagus) and solid or hollow organs (bowel, liver, stomach, brain, etc). The clinical studies presented successfully demonstrated the feasibility in acquiring PPGs and estimating blood oxygen saturation values from a variety of organs and tissues. The technological developments and the measurements presented in this work pave the way in a new era of pulse oximetry where direct and continuous monitoring of blood oxygen saturation of internal organs and tissues could be made possible

Non-invasive optical monitoring of free and bound oxygen in humans

Background: Possibilities of detecting oxygen - both in its free form, as gas in the lungs, and in its bound form, as oxygenated hemoglobin - have been explored in this thesis. Perfusion and oxygenation of vital organs (e.g., heart, brain and kidneys) may be severely compromised in critical illness or major trauma, which is why blood is rapidly diverted to those organs to improve chances of survival. Blood vessels in less important organs (e.g., skin, skeletal muscles and intestines) are constricted, leading to reduced regional perfusion and oxygenation in these organs. Non-invasive measurements of changes in tissue perfusion and oxygenation, in e.g., the forearm, might give an early indication of clinical deterioration. Preterm infants are very vulnerable patients. Their organs, in particular the lungs, are not fully developed, and the respiratory distress syndrome (RDS) frequently occurs. The intestines may be affected by necrotizing enterocolitis (NEC). Complementary diagnostic and surveillance methods of RDS and NEC are desirable. Aims: The overall aim of this thesis, which includes Studies I-IV, was to develop and evaluate non-invasive optical techniques, based on light at different wavelengths, to complement future bedside surveillance in critically illness or severe injury, for adults as well as for infants. Methods: Changes in tissue oxygenation by near-infrared spectroscopy (I-II), blood perfusion by laser Doppler imaging (I) and blood volume by tissue viability imaging (I) in skeletal muscle and skin were studied, and continuous-wave and timeresolved near-infrared spectroscopy were compared (II) in healthy volunteers subjected to various defined regional physiological perturbations. For the first time, gas in scattering media absorption spectroscopy (GASMAS) was used to detect alveolar water vapor (III-IV) and oxygen gas (IV), as well as intestinal water vapor (III) in newborn infants. Main results: Near-infrared spectroscopy, laser Doppler imaging and tissue viability imaging provided valuable information on physiological changes in the microcirculation (I). Continuous-wave and time-resolved near-infrared spectroscopy techniques were both able to determine changes in tissue oxygenation, but the time-resolved technique provided more realistic values with smaller inter-individual differences (II). Alveolar (III-IV) and intestinal signals of water vapor (III), were readily detected, together with alveolar signals of oxygen gas (IV), non-invasively in newborn infants. Conclusions: Optical techniques, being non-invasive and providing data in real-time, are attractive as potential tools for surveillance in critical illness or severe injury, in particular concerning the oxygenation. As an overall conclusion, we believe, that fully developed time-resolved near-infrared techniques have the potential to become an additional monitoring method of choice for surveillance of critically ill or severely injured patients. Likewise, GASMAS has great potential for future monitoring of critically ill preterm or full-term infants, and might, ultimately, reduce the current use of X-ray imaging in these most vulnerable patients

Applied aspect of Ashtasthana Pariksha w.s.r. to tools used in current era

Health is a state of equilibrium of the Dosha, Dhatu and Mala along with proper functioning of Indriya, Manas and Atma. To treat the disease, it is necessary to keep balance between Doshas and to bring back them into their normal condition. Ayurveda had described various tools to diagnose various diseases and one of them is Rog and Rogi Pariksha. For Rogi Pariksha, various Parikshas have been described like Dwividha Pariksha, Trividha Pariksha, Chaturvidha Pariksha, Panchvidha Pariksha, Ashtavidha Pariksha and Dashvidha Pariksha. Yogratnakara provides a clear picture of scenery of illness and healthy condition through Ashtavidha Pariksha. In current era, various diagnostic tools like urine examination, stool examination, tongue examination, auscultation, percussion, eye examination and gait examination are also very helpful in the prognosis of many common diseases. In current paper, attempts were made to study the relation of Ashtasthana Pariksha with special emphasis on tools used in modern era

Applications of sensory and physiological measurement in oral‐facial dental pain

Dentists regularly employ a variety of self‐report and sensory techniques to aid in the diagnosis and treatment of tooth‐related disease. Many of these techniques leverage principles borrowed from psychophysics, the quantitative measurement of the relationship between stimuli and evoked sensations, which falls under the larger umbrella of quantitative sensory testing (QST). However, most clinicians fail to meet the bar for what could be considered quantitative sensory testing, and instead focus on qualitative and dichotomous “yes/no” aspects of sensory experience. With our current subjective measurements for pain assessments, diagnosis and treatment of dental pain in young children and individuals (any age) with severe cognitive impairment rely extensively on third‐party observations. Consequently, the limitation of inadequate pain diagnosis can lead to poor pain management. In this review, it discusses mechanisms that underlie acute and chronic dental pain. It details the measurement of somatosensory responses and pulpal blood flow as objective measures of tooth health and pain. It proposes that bridging these varied methodologies will significantly improve diagnosis and treatment of orofacial pain and pathology. It concludes that improving the precision of sensory measurements could yield important improvements in diagnostic challenges in pulpal pathology for noncommunicative and cognitively impaired individuals.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146659/1/scd12323.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146659/2/scd12323_am.pd

Investigating optical path and differential pathlength factor in reflectance photoplethysmography for the assessment of perfusion

Photoplethysmography (PPG) is an optical noninvasive technique with the potential for assessing tissue perfusion. The relative time-change in the concentration of oxyhemoglobin and deoxyhemoglobin in the blood can be derived from DC part of the PPG signal. However, the absolute concentration cannot be determined due to the inadequate data on PPG optical paths. The optical path and differential pathlength factor (DPF) for PPG at red (660 nm) and infrared (880 nm) wavelengths were investigated using a heterogeneous Monte Carlo model of the human forearm. Using the simulated DPFs, the absolute time-change in concentrations were determined from PPG signals recorded from the same tissue site. Results were compared with three conditions of approximated DPFs. Results showed the variation of the optical-path and DPF with different wavelengths and source-detector separations. Approximations resulted in significant errors, for example, using NIRS DPF in PPG led to "cross talk" of -0.4297 and 0.060 and an error of 15.16% to 25.18%. Results confirmed the feasibility of using the PPG (DC) for the assessment of tissue perfusion. The study also identified the inappropriateness of the assumption that DPF is independent of wavelength or source-detector separations and set the platform for further studies on investigating optical pathlengths and DPF in PPG

SYSTEM AND METHODS FOR VENTILATION THROUGH A BODY CAVITY

A system and methods for the delivery of oxygen through a body cavity of a subject using oxygen microbubbles . Through circulation of oxygen microbubbles through the body cavity , oxygen and carbon dioxide exchange may occur . Overall improvement in extending survival rate time during emergency situations caused by pulmonary or similar oxygen - intake restricting injury and / or failure may be achieved through use of the invented system and methods

Clinical evaluation of a new optical fibre method of measuring oxygen saturation using photoplethysmograph signals reflected from internal tissues

MD (Res)Traditional methods of measuring oxygen saturation, e.g. pulse oximetry, depend on an adequate peripheral circulation and have a 20–30 second lag time before readings are obtained. This was a series of evaluations of novel optical probes, designed to measure oxygen saturation using fibreoptic technology directly from internal organs including the brain, oesophagus and organs with splanchnic circulations. A series of pilot studies were proposed and research ethics approval obtained to carry out studies in humans, under general anaesthesia, using these probes. Innovative reflectance probes were designed specifically for each of the four applications, so as to obtain potentially useful signals needed for signal processing, analysis and evaluation. Signals were successfully obtained from the brain, oesophagus and splanchnic region in almost all of the patients recruited. Good quality photoplethysmograph signals were recorded and these were translated into clinically meaningful values of oxygen saturation comparable to traditional methods of pulse oximetry. Overall, the signals were prone to movement artefacts as well as occasional interference from surgical diathermy and other sources. Nonetheless, the probes could prove to be a useful alternative to conventional external transmittance pulse oximetry methods as well as providing useful information regarding regional perfusion and oxygenation. The success of these pilot studies will form the basis of more research in the area and further development of such probes on the medical engineering front

Effects on the maternofetal unit of the rabbit model after substitution of the amniotic fluid with perfluorocarbons

Objectives: Exchanging amniotic fluid (AF) with perfluorocarbon (PFC) may serve as a medium for fetoscopic surgery. This study evaluates the distribution and physiologic effects of intraamniotic PFC as a medium for fetoscopy. Methods: Fetuses of 17 pregnant rabbits underwent either exchange of the AF with PFC, electrolyte solution (ES), or control. The quality of vision during fetoscopy was assessed in AF and PFC. After 6 h, we determined the distribution of PFC in the maternofetal unit. Results: Quality of vision during fetoscopy was better in PFC than with AF. There was no difference in fetal survival between the study groups. PFC was demonstrated on X-ray in the pharynx of 4 fetuses, and the esophagus in 1. Conclusions: PFC provided an ideal medium for fetoscopy without fetal compromise. Copyright (c) 2005 S. Karger AG, Basel

Hemodynamic Monitoring in Neonates

Sick neonates are often hemodynamically unstable, hence their organs are inadequately supplied with oxygen. In order to maintain blood flow to vital organs, a number of compensatory mechanisms divert the blood flow away from the non‐vital organs. If hemodynamic changes are detected early, the cardiovascular compromise can be recognized in compensated phase and thereby the escalation to decompensated phase of low cardiac output syndrome might be prevented. In the treatment of hemodynamically unstable neonate venous filling, contractility of the heart muscle, blood pressure in the aorta, systemic blood flow, and regional distribution of blood flow should be evaluated. There are many evaluation and measurement methods based on different physical basis, each of them having their advantages and disadvantages. For most of them, it has not been demonstrated that they improve outcomes of sick neonates. Using these methods, useful hemodynamic data for the treatment of sick neonates can be obtained. Using new techniques will clarify the pathophysiology of cardiovascular failure in sick neonates, assess the effects of drugs on blood pressure and perfusion of the heart and other organs