Investigation of signal processing algorithms for an embedded microcontroller-based wearable pulse oximeter.

Despite steady progress in the miniaturization of pulse oximeters over the years, significant challenges remain since advanced signal processing must be implemented efficiently in real-time by a relatively small size wearable device. The goal of this study was to investigate several potential digital signal processing algorithms for computing arterial oxygen saturation (SpO(2)) and heart rate (HR) in a battery-operated wearable reflectance pulse oximeter that is being developed in our laboratory for use by medics and first responders in the field. We found that a differential measurement approach, combined with a low-pass filter (LPF), yielded the most suitable signal processing technique for estimating SpO(2), while a signal derivative approach produced the most accurate HR measurements.

Extracting breathing rate information from a wearable reflectance pulse oximeter sensor.

The integration of multiple vital physiological measurements could help combat medics and field commanders to better predict a soldier's health condition and enhance their ability to perform remote triage procedures. In this paper we demonstrate the feasibility of extracting accurate breathing rate information from a photoplethysmographic signal that was recorded by a reflectance pulse oximeter sensor mounted on the forehead and subsequently processed by a simple time domain filtering and frequency domain Fourier analysis.

Correlates of suffering in amyotrophic lateral sclerosis.

OBJECTIVES: 1) To determine the prevalence of pain, suffering, poor quality of life, depression, and hopelessness in people with ALS, and the correlates of suffering and poor quality of life; 2) to analyze the relationship between pain, suffering, quality of life, and attitudes toward life-sustaining medical treatment and physician-assisted suicide; and 3) to determine concordance between patients with ALS and their caregivers in rating the patients' pain, quality of life, and suffering. METHODS: Subjects completed a single interview. We measured the subject's pain, quality of life, suffering, hopelessness, depression, social support, perception of burden to others, level of disability, desire for life-sustaining medical treatment, and interest in assisted suicide. Caregivers also rated the patient's quality of life, pain, and suffering. RESULTS: A total of 100 subjects with ALS and 91 caregivers participated. Suffering was rated as 4 or greater on a six-point scale by 20% of subjects with ALS, and 19% rated their pain as 4 or greater on a six-point scale. Eleven percent had clinical depression. Physicians frequently failed to recognize and treat pain and depression. The correlates of suffering were increasing pain, hopelessness, and level of disability. The correlates of poor quality of life were poor social support and increasing hopelessness. The correlation between subjects' and caregivers' rating of the patient's suffering was r = 0.47. There was no relationship between subjects' ratings of pain, suffering, and quality of life, and their interest in life-sustaining treatment or physician-assisted suicide. CONCLUSION: Many patients with ALS suffer, and their suffering is correlated to pain and hopelessness. Physicians caring for patients with ALS frequently fail to recognize and treat their patients' pain and depression.

Attitudes of patients with amyotrophic lateral sclerosis and their care givers toward assisted suicide.

BACKGROUND AND METHODS: Amyotrophic lateral sclerosis (ALS) is a neuromuscular disease that causes gradual paralysis, respiratory failure, and death, usually within three to five years after it has been diagnosed. Between 1995 and 1997, we surveyed patients with this disease in Oregon and Washington, as well as their family care givers, in order to determine their attitudes toward assisted suicide. Patients were considered to be willing to contemplate assisted suicide if they agreed with the statement, "Under some circumstances I would consider taking a prescription for a medicine whose sole purpose was to end my life," and disagreed with the statement, "I would never request or take a prescription for a medication whose sole purpose was to end my life." The Oregon Death with Dignity Act, which legalized physician-assisted suicide, was approved by Oregon voters in 1994 but did not go into effect until October 1997, after data collection for this study had been completed. RESULTS: Of 140 eligible persons with ALS, 100 (71 percent) agreed to participate in the study, as did 91 family care givers. The mean age of the patients with ALS was 54 years; the mean duration of illness since the diagnosis was 2.8 years. Fifty-six patients (56 percent) said they would consider assisted suicide, and 44 of the 56 agreed with the statement, "If physician-assisted suicide were legal, I would request a lethal prescription from a physician." One patient would have taken the medication immediately, and 36 would have kept it for future use. As compared with the patients who were opposed to assisted suicide, those who would consider it were more likely to be men, had a higher level of education, were less likely to be religious, had higher scores for hopelessness, and rated their quality of life as lower. In 66 of 91 instances (73 percent), care givers and patients had the same attitude toward assisted suicide. CONCLUSIONS: In Oregon and Washington, a majority of persons with ALS whom we surveyed would consider assisted suicide. Many would request a prescription for a lethal dose of medication well before they intended to use it.

A microdeletion in cytochrome c oxidase (COX) subunit III associated with COX deficiency and recurrent myoglobinuria.

We have identified a 15-bp microdeletion in a highly conserved region of the mitochondrially encoded gene for cytochrome c oxidase (COX) subunit III in a patient with severe isolated COX deficiency and recurrent myoglobinuria. The mutant mitochondrial DNA (mtDNA) comprised 92% of the mtDNA in muscle and 0.7% in leukocytes. Immunoblots and immunocytochemistry suggested a lack of assembly or instability of the complex. Microdissected muscle fibres revealed significantly higher portions of mutant mtDNA in COX-negative than in COX-positive fibres. This represents the first case of isolated COX deficiency to be defined at the molecular level.

Salmonella in sewage effluent and the relationship to animal and human disease in the north of Scotland.

During the period July 1982 to December 1984, the presence of salmonella organisms was investigated at weekly intervals in the sewage system and abattoir effluent of a town in the north of Scotland. Three hundred and fifteen isolations, representing 37 different serotypes, were made which included 20 different Salmonella typhimurium phage types and four different S enteritidis phage types. Ten of the serotypes were isolated from livestock in the district during the survey as well as in the periods immediately before and after the survey. There were seven recorded incidents of human infection, involving four salmonella serotypes, only three of which were isolated concurrently from sewage.

Palisade endings in human extraocular muscles.

The presence of nerve terminals in the tendinous insertions of human eye muscles was investigated histologically in adult human eye muscles obtained from donor eyes and in muscle pieces resected from juvenile patients undergoing surgical correction for strabismus. Lateral and medial recti, superior and inferior oblique muscles from adults, were stained "en bloc" using a silver impregnation method. Numbers of nerve terminals were isolated that resembled "palisade endings" previously described in other species. A single palisade ending usually appeared as an interwoven network of fine neural filaments that cupped the inserting tip of a single extrafusal fiber. A collection of palisade endings on several neighboring muscle fibers were supplied by a single myelinated axon that branched from a nerve bundle in the muscle mass. The presence of nerve terminals at the distal musculotendinous interface of juvenile muscle also was observed when some resected specimens of lateral and medial recti were sectioned and stained using Holmes' silver method with a picrofuschin counterstain. No conventional Golgi tendon organs were seen.

Salmonella montevideo infection in sheep and cattle in Scotland, 1970-81.

Outbreaks of abortion associated with infection by Salmonella montevideo have affected sheep in the east, especially the south-east, of Scotland each year since 1972. Disease in the north and north-east was usually less severe. Between 1 January 1970 and 31 December 1981, a total of 67 incidents affecting sheep were reported by veterinary laboratories to the Communicable Diseases (Scotland) Unit, 87% of which presented during the main lambing months of February, March and April. Twenty-one episodes of bovine infection were also recorded over the same period, 17 of which involved single animals only, usually an aborted cow or a scouring calf. Despite intensive investigations, neither the origin nor the mode of spread of S. montevideo infection among sheep and cattle in Scotland have been established with any certainty, although there has been considerable evidence indicating the role of scavenging wild birds, particularly seagulls, as vectors transmitting infection to other farms in the same district. Also largely unexplained are the differences in the epidemiology and clinical pattern of disease in the south-east compared to the north and north-east, while sheep in the west of Scotland have remained virtually unaffected throughout.

Copper poisoning in sheep from North Ronaldsay maintained on a diet of terrestrial herbage.

Copper toxicity occurred in North Ronaldsay sheep fed on a diet of terrestrial herbage relatively high in molybdenum. Five sheep were taken from the island of North Ronaldsay, Orkney to the veterinary investigation centre at Thurso and fed solely on the herbage of the laboratory paddocks, supplemented in winter by hay made from these paddocks. The level of copper, molybdenum, zinc and total sulphur in the terrestrial herbage was analysed, together with the seaweeds which form the major part of the diet on North Ronaldsay. Serum copper, vitamin B12 and serum aspartate aminotransferase levels were obtained. Four of the five sheep died on this diet of terrestrial herbage and had liver copper levels of 1379, 1723, 2279 and 2281 mg/kg. The susceptibility of the North Ronaldsay breed of Orkney sheep to copper poisoning when first introduced to a diet of purely terrestrial herbage is demonstrated by the high liver copper levels of the four dead sheep compared to the normal serum copper levels and unimpaired health of two other breeds of sheep and a north country Cheviot cross North Ronaldsay ram.

An unusual sequel to imported Salmonella zanzibar.

In August, 1980 a rare serotype S. zanzibar was isolated in the North of Scotland from a man home on leave from Malaysia, whence he returned in November having been bacteriologically negative 2 months previously. In December however, S. zanzibar was isolated from a bulk milk sample taken at a nearby dairy farm. No illness occurred among milking cows which had been brought inside from pasture in mid-October. Since 1972 a variety of different salmonella serotypes had been identified in cattle, milk and other samples at this farm, with seagulls being implicated as the vector transmitting infection from the sewage of a local town on to farmland and an adjacent loch. Although water from this source has not been used in recent years for drinking by cattle, it is utilized for washing floors within the dairy premises. Since 1979, following an outbreak affecting consumers, all milk produced at the farm has been pasteurized.

A survey of sheep losses and their causes on commercial farms in the north of Scotland.

A three year survey on sheep deaths and their causes was conducted on 10 commercial farms in the north of Scotland. Diseases and other trauma associated with the perinatal period accounted for 56.81% of all ewe deaths, while pneumonia, parasitic gastroenteritis, torsion of the bowel and haemorrhagic enteritis (redgut) accounted for a further 21.7%. No one disease condition predominated in the rams and hoggs. In lambs, most deaths occurred between birth and four days old (77.86%). Causes came in the form of starvation and exposure (34.2%), stillbirths (18.2%), lambing injuries (11.06%), infectious conditions (8.0%), dystocia (7.6%) and abortion (5.2%). The overall death rate among the lambs was 14.2%.

The association of non-clotting of cow's milk with scour in the single suckled beef calf.

An apparent correlation between the clotting ability of cows milk and the prevalence of scour in suckling calves was investigated. Fifty-eight per cent of the milk samples of mothers of scouring single suckled calves showed impaired clotting ability. While the cause of this remains unknown there appears to be a link with diet. The poor clotting ability is probably a contributory factor in the aetiology of scour in the suckler calf, as the abnormality has only been seen in the milk from mothers of scouring calves.

The possible involvement of seagulls (Larus sp) in the transmission of salmonella in dairy cattle.

A series of infections in a herd of dairy cows by different salmonella serotypes over a seven year period is described. The source of infection appeared to be the private water supply contaminated by seagulls.