Investigation of Photoplethysmographic Signals in Human Visceral Organs

There is a need for reliable continuous monitoring of visceral organ oxygen saturation (SpO2). Splanchnic ischaemia may ultimately lead to cellular hypoxia and necrosis and may well contribute to the development of multiple organ failures and increased mortality. A new reflectance photoplethysmographic (PPG) probe and signal processing system were developed. PPG signals from abdominal organs (bowel, liver, and kidney) and the finger were obtained from 12 anaesthetised patients. The amplitudes of the abdominal organ PPGs were, on average, approximately the same as those obtained simultaneously from the finger. These observations suggest that pulse oximetry may be a valid monitoring technique for abdominal organs such as the bowel liver and kidney

A new system for estimating human splanchnic oxygen saturation

Adequate splanchnic oxygen saturation (SpO2) is essential for maintaining organ viability during and after surgery. There is a need for reliable continuous monitoring of organ oxygen saturation. A new photoplethysmographic (PPG) probe and signal processing system were developed. PPG signals from abdominal organs (bowel, liver, kidney) and the finger were obtained from 12 anaesthetised patients. The amplitudes of the abdominal organ PPGs were, on average, approximately the same as those obtained simultaneously from the finger. Preliminary SpO2 values from abdominal organs showed good agreement with those obtained simultaneously from a commercial finger pulse oximeter

Measurement of photoplethysmographic signals in human abdominal organs

There is a need for reliable continuous monitoring of abdominal organ oxygen saturation (SpO2). Splanchnic ischaemia may ultimately lead to cellular hypoxia and necrosis and contribute to the development of multiple organ failure and increased mortality. A reflectance electro-optical photoplethysmographic (PPG) probe and signal processing system were developed. Satisfactory PPG signals from abdominal organs (bowel, liver and kidney) and the finger were obtained from 12 anaesthetised patients. There were no statistically significant differences between the average PPG amplitudes recorded from the abdominal organs and those obtained simultaneously from the finger. These observations suggest that pulse oximetry can be a valid monitoring technique for abdominal organs such as the bowel, liver and kidney

Electro-optical techniques for the investigation of photoplethysmographic signals in human abdominal organs

There is a need for reliable continuous monitoring of abdominal organ oxygen saturation (SpO2). Splanchnic ischaemia may ultimately lead to cellular hypoxia and necrosis and may well contribute to the development of multiple organ failures and increased mortality. A new reflectance electro-optical photoplethysmographic (PPG) probe and signal processing system were developed. PPG signals from abdominal organs (bowel, liver, and kidney) and the finger were obtained from 12 anaesthetised patients. The amplitudes of the abdominal organ PPGs were, on average, approximately the same as those obtained simultaneously from the finger. These observations suggest that pulse oximetry may be a valid monitoring technique for abdominal organs such as the bowel liver and kidney

Assessment of photoplethysmographic signals for the determination of splanchnic oxygen saturation in humans

The need for a clinically applicable method of detecting splanchnic hypoxia has led to experimental animal studies which indicated the usefulness of intestinal pulse oximetry. Pulse oximetry relies on detection of photoplethysmographic signals. Before developing a pulse oximeter for the measurement of organ oxygen saturation peri-operatively, we designed a system based on a reflectance photoplethysmographic probe to investigate photoplethysmographic signals from human viscera (bowel, liver, and kidney). Recordings were obtained simultaneously from the abdominal viscera and the finger using identical probes. The probe was held sequentially for up to 2 min on the surface of viscera of 12 patients during routine laparotomy. Measurable splanchnic photoplethysmographic signals were recorded for the first time in humans. There were no statistically significant differences between photoplethysmographic amplitudes from viscera and those from the finger. Our results indicate the feasibility of pulse oximetry for the measurement of visceral oxygenation in humans

A Comparison of Computerized Chemical Models for Equilibrium Calculations in Aqueous Systems

A survey of computer programs which are currently being used to calculate the distribution of species in aqueous solutions, especially natural waters, has been made in order to 1) provide an inventory of available programs with a short description of their uses, 2) compare the consistency of their output for two given test solutions and 3) identify major weaknesses or problems encountered from their use. More than a dozen active programs which can be used for distribution of species and activity calculations for homogeneos equilibria among the major anions and cations of natural waters have been inventoried. Half of these programs can also accept several trace elements including Fe, Al, Mn, Cu, Ni, Zn, Cd, Pb, Ag, Hg, As, Ba, Sr, and B. Consistency between programs was evaluated by comparing the log of the molal concentrations of free ions and complexes for two test solutions: a hypothetical seawater analysis and a hypothetical river water analysis. Comparison of the free major ion concentrations in the river water test case shows excellent agreement for the major species. In the seawater test case there is less agreement and for both test cases the minor species commonly show orders of magnitude differences in concentrations. These differences primarily reflect differences in the thermodynamic data base of each chemical model although other factors such as activity coefficient calculations, redox assumptions, temperature corrections, alkalinity corrections and the number of complexes used all have an affect on the output

Investigation of photoplethysmographic signals and blood oxygen saturation values obtained from human splanchnic organs using a fiber optic sensor

Objective A reliable, continuous method of monitoring splanchnic organ oxygen saturation could allow for the early detection of malperfusion, and may prevent the onset of multiple organ failure. Current monitoring techniques have not been widely accepted in critical care monitoring. As a preliminary to developing a continuous indwelling device, this study evaluates a new handheld fiber optic photoplethysmographic (PPG) sensor for estimating the blood oxygen saturation (SpO2) of splanchnic organs during surgery. Methods A fiber optic splanchnic PPG sensor, instrumentation system and virtual instrument were developed to facilitate PPG and SpO2 measurement from splanchnic organs. Following Local Research Ethics Committee approval, the sensor was evaluated on seventeen ASA 1 and 2 patients undergoing open laparotomy. PPG signals were obtained from the large bowel, small bowel, liver and stomach. Simultaneous PPG signals from the finger were also obtained using an identical fiber optic sensor. Results Good quality PPG signals with high signal-to-noise (SNR) ratios were obtained from all splanchnic sites under investigation. Analysis of the ac and dc amplitudes of the red and infrared PPG signals showed there to be a statistically significant difference between PPG signals obtained from splanchnic organs with those obtained from the finger (using fiber optic sensors). Estimated SpO2 values from the splanchnic organs show good agreement with those obtained from the finger using both a fiber optic sensor and a commercial device. Furthermore, the results of a Bland and Altman analysis indicate that fiber optic splanchnic pulse oximetry, particularly of the bowel, may provide a suitable method for monitoring splanchnic organ perfusion. Conclusion The evaluation of a new fiber optic sensor on anaesthetized patients undergoing laparotomy demonstrated that good quality PPG signals and SpO2 estimates can be obtained from splanchnic organs. Such a sensor may provide a useful tool for the intraoperative assessment of splanchnic perfusion

Internationally Distributed Frozen Oyster Meat Causing Multiple Outbreaks of Norovirus Infection in Australia.

Background. Between November 2003 and January 2004, outbreaks of norovirus in 3 Australian jurisdictions involving 83 cases of illness were associated with imported oyster meat. Methods. Cohort studies were conducted in 2 jurisdictions to identify relative risks of illness for the consumption of oysters. A case series was conducted in the third jurisdiction. Results. The cohort studies conducted in the first 2 jurisdictions identified relative risks of illness of 17 (95% confidence interval, 5-51) and 35 (95% confidence interval, 5-243), respectively, for the consumption of oysters. Multiple strains of norovirus were detected in fecal specimens from 8 of 14 patients and in 1 of the 3 batches of implicated oyster meat using seminested reverse-transcriptase polymerase chain reaction methods. Traceback investigations revealed that all oyster meat was harvested from the same estuary system in Japan within the same month. Conclusions. These outbreaks demonstrate the potential of foodborne disease to spread internationally and the need for national and international collaboration to investigate such outbreaks. Foodborne illness related to norovirus is underestimated because of underreporting of human cases and challenges in laboratory detection of viruses in foods, both of which can delay public health action