Public health risks of raw milk consumption: Lessons from a case of paediatric hemolytic uremic syndrome

Pasteurization of raw milk is mandatory before sale in Canada and has been demonstrated to reduce the risk of food-borne illness associated with milk consumption. Consumption of raw milk sparks urgent concern from a public health perspective since it has been linked to numerous outbreaks by enteric organisms, particularly Escherichia coli-related illnesses and complications in pediatric populations. The sale and distribution of raw milk is illegal in Canada, based on these significant health risks, but growing popular interest and trends in consuming raw dairy products reflect changes in consumer preferences. Although the consumption of raw milk has been an ongoing issue, this new trend is alarming and action is needed to prevent serious consequences as seen in children and other populations with reduced immunity such as the elderly and pregnant people. This commentary explores key issues identified by a local public health unit during the investigation of a recent paediatric case of hemolytic uremic syndrome related to an E. coli O157:H7 infection that occurred within the context of consumption of raw milk. The main objective of this article is to highlight that the health risks and sequelae associated with consumption of raw milk far outweigh any potential benefits, with severe consequences particularly among children. Data and health impacts, distribution, regulation, pasteurization and proposed practice recommendations are also identified and discussed.

Seropositivity and risk factors for SARS-CoV-2 infection in a South Asian community in Ontario: a cross-sectional analysis of a prospective cohort study

BACKGROUND

Early in the COVID-19 pandemic, the South Asian community in the Greater Toronto Area (GTA) was identified as having risk factors for exposure and specific barriers to accessing testing and reliable health information, rendering them particularly vulnerable to SARS-CoV-2 infection. We sought to investigate the burden of SARS-CoV-2 infection among South Asian people in the GTA, and to characterize the demographic characteristics, risk perceptions and trusted sources of health information in this group.

METHODS

We conducted a cross-sectional analysis from the baseline assessment of participants in a prospective cohort study. Participants from the GTA were enrolled from Apr. 14 to July 28, 2021. Seropositivity for antispike and antinucleocapsid antibodies was determined from dried blood spots, and estimates of seropositivity were age and sex standardized to the South Asian population in Ontario. Demographic characteristics, risk perceptions and sources of COVID-19 information were collected via questionnaire and reported descriptively.

RESULTS

Among the 916 South Asian participants enrolled (mean age 41 yr), the age- and sex-standardized seropositivity was 23.6% (95% confidence interval 20.8%-26.4%). Of the 693 respondents to the questionnaire, 228 (32.9%) identified as essential workers, and 125 (19.1%) reported living in a multigenerational household. A total of 288 (49.4%) perceived that they were at high COVID-19 risk owing to their geographic location, and 149 (34.3%) owing to their type of employment. The top 3 most trusted sources of information related to COVID-19 included health care providers and public health, traditional media sources and social media.

INTERPRETATION

By the third wave of the COVID-19 pandemic, about one-quarter of a sample of South Asian individuals in Ontario had serologic evidence of prior SARS-CoV-2 infection. Insight into factors that put certain populations at risk can help future pandemic planning and disease control efforts.

Transnasal sphenopalatine ganglion block for post-dural puncture headache and associated tinnitus

Lumbar epidurals are frequently inserted for women in labour as they provide excellent analgesia. One of the more common procedural complications is post-dural puncture headache which can be associated with auditory symptoms such as hearing loss and tinnitus and can be treated with an epidural blood patch. Sphenopalatine ganglion blocks have also been used to treat post-dural puncture headache but have not been previously shown to resolve the associated tinnitus. We report a case where postural neck pain and tinnitus from an accidental dural puncture during lumbar epidural insertion for labour analgesia was treated successfully with a sphenopalatine ganglion block. Further, we explore the literature on the cause of tinnitus in post-dural puncture headache and the possible mechanism by which a sphenopalatine ganglion block relieves both post-dural puncture headache and the associated tinnitus.

Factor price distortion and ecological efficiency: the role of institutional quality

There is a lack of studies on whether market distortions inhibit the ecological efficiency. This study introduces the ecological efficiency based on the bootstrap-data envelopment analysis (DEA) method as the indicator of environmental performance in China, uses the transcendental logarithmic production function to calculate factor price distortion, and further identifies whether the factor price distortion has a negative impact on the ecological efficiency using the system generalized method of moments (GMM) method. Meanwhile, institutional quality is considered a threshold variable to examine the relationship between factor price distortion and ecological efficiency based on the threshold model. The result shows that factor price distortion significantly inhibits the improvement of ecological efficiency. Moreover, institutional quality is considered to be the threshold of factor price distortion affecting ecological efficiency. Further investigation of heterogeneity effect suggests that the inhibitory impact of factor price distortion on ecological efficiency is more significant in the central and western regions. This study provides a supplement to the study on environmental performance from the perspective of factor distortions and expands the framework of the influence mechanism of factor price distortion affecting ecological efficiency.

Effect of market fragmentation on ecological efficiency: evidence from environmental pollution in China

Local governments restrict cross-regional flows of factors and products for achieving the purpose of profit, which lead to market fragmentation. China's domestic market is fragmented, leading to the situation that market boundaries are demarcated. We use the relative price method to measure market fragmentation and find that market fragmentation is indeed a serious problem in China. This study evaluates the ecological efficiency using the bootstrap DEA method that takes air and water pollution into account and investigates the effect of market fragmentation on ecological efficiency based on the system GMM approach by employing data from a panel of 29 provinces in China during the period 2000-2015. The results indicate that there are differences in ecological efficiency among provinces. The market fragmentation has negative impact on ecological efficiency, which shows market fragmentation significantly inhibits the improvement of ecological efficiency. The similar findings are confirmed by a series of robustness tests, which include the alternative indicator and sub-sample regression. Based on the above findings, the central government should reduce market fragmentation, promote market integration, increase the efficiency of resource allocation, and improve environmental quality.

Major liver surgery in a Jehovah’s Witness patient: challenges for safe surgery

Jehovah’s Witnesses presenting for major surgery run the risk of major bleeding, which is complicated by the refusal to accept blood transfusion. We present a case of a 63-year-old woman, a Jehovah’s Witness, who was diagnosed with hepatocellular carcinoma and advised for curative laparoscopic liver segmentectomy. Due to the risk of significant intraoperative haemorrhage, her perioperative care was coordinated in a multidisciplinary manner. Informed consent requires the physician to advise on the material risks of undertaking major surgery without blood transfusion and the possible alternatives. Conflicting ethical issues of patient autonomy and beneficence related to refusal of blood products also arise. Perioperative strategies to minimise blood loss, maximise haematopoiesis and tolerance of anaemia to facilitate safe surgery in such patients are also presented. Written patient consent obtained.

Lessons learned from the development and implementation of a citywide stair prompt initiative

Stair climbing is a readily available form of vigorous-intensity physical activity. Evidence indicates that placing stair prompt signs at points-of-decision (e.g. near elevators and stairways) is an inexpensive, effective strategy for increasing physical activity through stair use. This article aims to share the experience of the New York City Department of Health and Mental Hygiene (NYC DOHMH) in the outreach and implementation of a population-scale stair prompt initiative, including lessons learned from process evaluations, with other public health authorities conducting a similar program. Between May 2008 and August 2012, NYC DOHMH implemented a stair prompt initiative as one strategy in a comprehensive program to increase physical activity and healthy eating through physical improvements to NYC's buildings, streets and neighborhoods, particularly targeting facilities in underserved and low-income neighborhoods. Program evaluation was conducted using program planning documents to examine the process, and data from NYC information line call center, outreach tracking database, and site and phone audits to examine process outcomes. The initiative successfully distributed more than 30,000 stair prompts to building owners/managers of over 1000 buildings. Keys to success included multi-sector partnerships between NYC's Health Department and non-health government agencies and organizations (such as architecture and real estate organizations), a designated outreach coordinator, and outreach strategies targeting building owners/managers owning/managing multiple buildings and buildings serving underserved and at risk populations. A NYC citywide initiative successfully distributed stair prompts to the wider community to promote population-level health impacts; lessons learned may assist other jurisdictions considering similar initiatives to increase physical activity.

Characterizing a community health partnership in Dominican Republic: Network mapping and analysis of stakeholder perceptions

BACKGROUND

Medical trainees complete learning experiences abroad to fulfil global health curricular elements, but this participation has been steadily criticized as fulfilling learner objectives at the cost of host communities. This study uses network and qualitative analyses in characterizing a community coalition in order to better understand its various dimensions and to explore the perceived benefits it provided towards optimizing community outcomes.

METHODS

Data from a semi-structured survey was used for network and qualitative analyses. Partner linkages were assessed using network analysis tool UCINET 6 (version 6.6). Thematic analysis was conducted on qualitative responses around the perceived coalition strengths and weaknesses.

RESULTS

Network analysis confirmed that local member organizations were key network influencers based on reported formal agreements, general interactions, and information shared. While sharing of resources was rare, qualitative analysis suggested that information sharing contributed to engagement, enthusiasm, and communication that allowed visiting partners to expand their understanding of community needs and shift their focus beyond learner objectives.

CONCLUSION

Global health programs for medical students should consider the use of community health coalitions to optimally align the work undertaken by learners on global health experiences abroad. Network mapping can help educators and coalition partners visualize interactions and identify value.

Perovskite BiFeO3 thin film photocathode performance with visible light activity

Perovskite materials are now an important class of materials in the application areas of photovoltaics and photocatalysis. Inorganic perovskites such as BiFeO3 (BFO) are promising photocatalyst materials with visible light activity and inherent stability. Here we report the large area sol-gel synthesis of BFO films for solar stimulated water photo oxidation. By modifying the sol-gel synthesis process we have produced a perovskite material that has p-type behaviour and a flat band potential of ∼1.15 V (versus NHE). The photocathode produces a density of -0.004 mA cm(-2) at 0 V versus NHE under AM1.5 G illumination. We further show that 0.6 μmol h(-1) of O2 was produced at an external bias of -0.5 V versus Ag/AgCl. The addition of a non-percolating conducting network of Ag increases the photocurrent to -0.07 mA cm(-2) at 0 V versus NHE (at 2% Ag loading) with an increase to 2.7 μmol h(-1) for O2 production. We attribute the enhancement in photoelectrochemical performance to increased light absorption due light scattering by the incorporated Ag particles, improved charge transfer kinetics at the Ag/BFO interface and reduced over potential losses. We support these claims by an observed shift in flat band and onset potentials after Ag modification through UV-vis spectroscopy, Mott-Schottky plots and j-v curve analysis.

Sexual health knowledge in a vulnerable population: a survey of adolescents in the bateyes of La Romana, Dominican Republic

OBJECTIVE

Undocumented Haitian migrants to the Dominican Republic often live in impoverished communities called bateyes. These contexts present challenges for adolescent sexual health education. To inform development of appropriate adolescent education programs, this study assessed their general sexual health knowledge.

METHODS

A locally developed sexual health knowledge survey was administered to 930 grade 7-12 adolescents attending six batey schools. Analysis of aggregated responses reviewed general demographics (e.g. age and sex), and identified top community sexual health concerns and most trusted information sources.

RESULTS

Top concerns included menstruation (25.5%), HIV (21.8%), and family planning (13.3%); stratification by sex identified discordance around menstruation (89.2% female, 10.8% male) and HIV (67.1% male, 32.9% female), but not family planning (47.2% male, 52.8% female). Parents were identified as the most trusted information source, irrespective of concern.

CONCLUSION

Community concerns around menstruation matches extant developing-world literature that links menarche with female stigma and school absence. Interest in HIV and family planning suggests targeted promoted efforts would be of benefit. Trust in parents is reflective of cultural traditions and suggests potential knowledge impacts arising from effective parental education.

Developing an ethical framework for short-term international dental and medical activities

The popularity of volunteering to provide charity health care in third-world countries has increased dramatically in recent years. While there are advantages to both those being helped and to volunteers, there are also ethical issues that need to be addressed. A framework for analyzing the ethical impact of such service is presented which continues 27 principles that should be addressed.

Acute fatal haemorrhage during percutaneous dilatational tracheostomy

Percutaneous dilatational tracheostomy (PDT) is associated with a number of life-threatening complications. We present a case of massive and fatal arterial haemorrhage that occurred in the intensive care unit during an elective PDT on an 86-year-old woman following earlier evacuation of a traumatic subdural haematoma. An avulsed right subclavian artery was found at post mortem. Previous thyroid surgery and aberrant arterial anatomy contributed to the fatal outcome.

Chondrocyte death precedes structural damage in blunt impact trauma

Joint impact trauma has been shown to cause fissures, fibrillation, and other structural damage of the cartilage or subchondral bone. Previous studies used impact energies sufficient to fracture the underlying bone. Under these circumstances, the initial influence of impact trauma on cellular components and cartilage structure is unknown. The goal of this study was to determine whether an impact trauma first causes cellular or structural damage to a cartilage layer. Such damage might be the starting point of degenerative changes found in osteoarthrosis. Porcine patellas (n = 12) were subjected to standardized low-impact loading of three magnitudes with a spherical impactor attached to a drop tower device (0.06, 0.1, and 0.2 J). India ink staining and scanning electron microscopic analysis were used for analysis and showed no evidence of gross structural disruption. Chondrocyte viability assessed with thiazole blue staining and propidium iodide counterstaining was reduced significantly in the tangential and middle zones with increasing impact energy. These results indicate that chondrocyte death may precede excessive structural damage reported in earlier studies and might be a crucial factor in posttraumatic osteoarthrosis.

Effect of transdermal testosterone treatment on serum lipid and apolipoprotein levels in men more than 65 years of age

PURPOSE

Because the effects of androgen replacement on lipoprotein levels are uncertain, we sought to determine the effect of transdermal testosterone treatment on serum lipid and apolipoprotein levels in elderly men.

SUBJECTS AND METHODS

One hundred and eight healthy men more than 65 years of age who had serum testosterone concentrations >1 SD below the mean for young men were randomly assigned to receive either testosterone (54 men; 6 mg/day) or placebo (54 men) transdermally in a double-blind fashion for 36 months. Serum concentrations of lipids and apolipoproteins were measured, and cardiovascular events recorded.

RESULTS

Serum total cholesterol concentrations decreased in both the testosterone-treated men and placebo-treated men, but the 3-year mean (+/- SD) decreases in the two groups (testosterone treated, -17 +/- 29 mg/dL; placebo treated, -12 +/- 38 mg/dL) were not significantly different from each other (P = 0.4). Similarly, serum low-density lipoprotein (LDL) cholesterol levels decreased in both treatment groups, but the decreases in the two groups (testosterone treated, -16 +/- 24 mg/dL; placebo treated, -16 +/- 33 mg/dL) were similar (P = 1.0). Levels of high-density lipoprotein (HDL) cholesterol, triglycerides, and apolipoproteins A-I and B did not change. Lipoprotein(a) levels increased in both groups by similar amounts (testosterone treated, 3 +/- 9 mg/dL; placebo treated, 4 +/- 6 mg/dL; P = 1.0). The number of cardiovascular events was small and did not differ significantly between the testosterone-treated men (9 events) and the placebo-treated men (5 events) during the 3-year study (relative risk = 1.8; 95% confidence interval: 0.7 to 5.0).

CONCLUSIONS

As compared with placebo, transdermal testosterone treatment of healthy elderly men for 3 years did not affect any of the lipid or apolipoprotein parameters that we measured. The effect of testosterone treatment on cardiovascular events was unclear, because the number of events was small.

Effects of testosterone replacement in hypogonadal men

Treatment of hypogonadal men with testosterone has been shown to ameliorate the effects of testosterone deficiency on bone, muscle, erythropoiesis, and the prostate. Most previous studies, however, have employed somewhat pharmacological doses of testosterone esters, which could result in exaggerated effects, and/or have been of relatively short duration or employed previously treated men, which could result in dampened effects. The goal of this study was to determine the magnitude and time course of the effects of physiological testosterone replacement for 3 yr on bone density, muscle mass and strength, erythropoiesis, prostate volume, energy, sexual function, and lipids in previously untreated hypogonadal men. We selected 18 men who were hypogonadal (mean serum testosterone +/- SD, 78 +/- 77 ng/dL; 2.7 +/- 2.7 nmol/L) due to organic disease and had never previously been treated for hypogonadism. We treated them with testosterone transdermally for 3 yr. Sixteen men completed 12 months of the protocol, and 14 men completed 36 months. The mean serum testosterone concentration reached the normal range by 3 months of treatment and remained there for the duration of treatment. Bone mineral density of the lumbar spine (L2-L4) increased by 7.7 +/- 7.6% (P < 0.001), and that of the femoral trochanter increased by 4.0 +/- 5.4% (P = 0.02); both reached maximum values by 24 months. Fat-free mass increased 3.1 kg (P = 0.004), and fat-free mass of the arms and legs individually increased, principally within the first 6 months. The decrease in fat mass was not statistically significant. Strength of knee flexion and extension did not change. Hematocrit increased dramatically, from mildly anemic (38.0 +/- 3.0%) to midnormal (43.1 +/- 4.0%; P = 0.002) within 3 months, and remained at that level for the duration of treatment. Prostate volume also increased dramatically, from subnormal (12.0 +/- 6.0 mL) before treatment to normal (22.4 +/- 8.4 mL; P = 0.004), principally during the first 6 months. Self-reported sense of energy (49 +/- 19% to 66 +/- 24%; P = 0.01) and sexual function (24 +/- 20% to 66 +/- 24%; P < 0.001) also increased, principally within the first 3 months. Lipids did not change. We conclude from this study that replacing testosterone in hypogonadal men increases bone mineral density of the spine and hip, fat-free mass, prostate volume, erythropoiesis, energy, and sexual function. The full effect of testosterone on bone mineral density took 24 months, but the full effects on the other tissues took only 3-6 months. These results provide the basis for monitoring the magnitude and the time course of the effects of testosterone replacement in hypogonadal men.

Effect of testosterone treatment on body composition and muscle strength in men over 65 years of age

As men age, serum testosterone concentrations decrease, the percentage of body mass that is fat increases, the percentage of lean body mass decreases, and muscle strength decreases. Because these changes are similar to those that occur in hypogonadal men, we hypothesized that increasing the serum testosterone concentration of men over 65 yr of age to that in young men would decrease their fat mass, increase their lean mass, and increase their muscle strength. We randomized 108 men over 65 yr of age to wear either a testosterone patch or a placebo patch in a double blind study for 36 months. We measured body composition by dual energy x-ray absorptiometry and muscle strength by dynamometer before and during treatment. Ninety-six men completed the entire 36-month protocol. Fat mass decreased (-3.0+/-0.5 kg) in the testosterone-treated men during the 36 months of treatment, which was significantly different (P = 0.001) from the decrease (-0.7+/-0.5 kg) in the placebo-treated men. Lean mass increased (1.9+/-0.3 kg) in the testosterone-treated men, which was significantly different (P < 0.001) from that (0.2+/-0.2 kg) in the placebo-treated men. The decrease in fat mass in the testosterone-treated men was principally in the arms (-0.7+/-0.1 kg; P < 0.001 compared to the placebo group) and legs (-1.1+/-0.2 kg; P < 0.001), and the increase in lean mass was principally in the trunk (1.9+/-0.3 kg; P < 0.001). The change in strength of knee extension and flexion at 60 degrees and 180 degrees angular velocity during treatment, however, was not significantly different between the two groups. We conclude that increasing the serum testosterone concentrations of normal men over 65 yr of age to the midnormal range for young men decreased fat mass, principally in the arms and legs, and increased lean mass, principally in the trunk, but did not increase the strength of knee extension and flexion, as measured by dynamometer.

Effect of testosterone treatment on bone mineral density in men over 65 years of age

As men age, their serum testosterone concentrations decrease, as do their bone densities. Because bone density is also low in hypogonadal men, we hypothesized that increasing the serum testosterone concentrations of men over 65 yr to those found in young men would increase their bone densities. We randomized 108 men over 65 yr of age to wear either a testosterone patch or a placebo patch double blindly for 36 months. We measured bone mineral density by dual energy x-ray absorptiometry before and during treatment. Ninety-six men completed the entire 36-month protocol. The mean serum testosterone concentration in the men treated with testosterone increased from 367 +/- 79 ng/dL (+/-SD; 12.7 +/- 2.7 nmol/L) before treatment to 625 +/- 249 ng/dL (21.7 +/- 8.6 nmol/L; P < 0.001) at 6 months of treatment and remained at that level for the duration of the study. The mean bone mineral density of the lumbar spine increased (P < 0.001) in both the placebo-treated (2.5 +/- 0.6%) and testosterone-treated (4.2 +/- 0.8%) groups, but the mean changes did not differ between the groups. Linear regression analysis, however, demonstrated that the lower the pretreatment serum testosterone concentration, the greater the effect of testosterone treatment on lumbar spine bone density from 0-36 months (P = 0.02). This analysis showed a minimal effect (0.9 +/- 1.0%) of testosterone treatment on bone mineral density for a pretreatment serum testosterone concentration of 400 ng/dL (13.9 nmol/L), but an increase of 5.9 +/- 2.2% for a pretreatment testosterone concentration of 200 ng/dL (6.9 nmol/L). Increasing the serum testosterone concentrations of normal men over 65 yr of age to the midnormal range for young men did not increase lumbar spine bone density overall, but did increase it in those men with low pretreatment serum testosterone concentrations.

Integrating Buddhism and HIV prevention in U.S. southeast Asian communities

Asian Pacific Islander communities in the United States have experienced an alarming increase in HIV infection over the past few years, possibly due to a lack of knowledge and the relative absence of appropriate educational interventions. The authors propose a new approach to the development of HIV prevention programs in U.S. southeast Asian communities. This article reviews the cultural and economic factors that may facilitate HIV transmission within these communities. Relying on the basic precepts of Buddhism, the dominant religion of many southeast Asian populations in the United States, the health belief model is utilized to demonstrate how recognizable, acceptable religious constructs can be integrated into the content of HIV prevention messages. This integration of religious concepts with HIV prevention messages may increase the likelihood that the message audience will accept the prevention messages as relevant. This nuanced approach to HIV prevention must be validated and refined through field research.

The Adoption of Internet-Based Stock Trading: A Conceptual Framework and Empirical Results

The adoption and diffusion of innovative technologies have remained critical concerns in information systems research. With the recent advent of electronic commerce, issues in system deployment and user acceptance have become even more crucial. An experimental system, Stocknet, which is a departure from normal practice in the local stock exchange which still uses conventional methods for share transactions, was developed and subjected to a pilot test through a stock trading competition using live stock data. A research framework was developed with the main emphasis on the adoption and deployment of a broad-based Internet stock-trading platform in Singapore. A logistic regression analysis was conducted to predict user acceptance of a new system from a measure of their perceptions, beliefs and attitudes and usage behaviour. The study reveals that users’ concerns, expectations, perceived ease of use and the real value added of a new system as well as their trading behaviour are critical determinants to the ultimate adoption of Internet stock trading. In fact, the probability of users accepting a new system is highly dependent on their perceptions of system evaluations and subsequently their usage behaviour. The primary focus of this paper is on users’ perspectives with a view towards a subsequent examination of policy as well as regulatory issues. Based on the results, some broad recommendations and implications are subsequently drawn with regard to the future adoption and deployment of real-time, Internet-based stock trading.

HIV prevention in U.S. Asian Pacific Islander communities: an innovative approach

Few HIV prevention efforts have focused on Asian Pacific Islander communities in the United States. Prevention messages developed for the general U.S. population have failed to reach many Asian Pacific Islanders. This article describes the development of an HIV prevention strategy for Asian Pacific Islanders through health care workers. This strategy was based on the ecological disease theory and action research methodology. The prevention program comprised four components: (1) a symposium for the health care workers, (2) a culturally sensitive and appropriate HIV-related video for the health care workers and their patients, (3) ongoing training of the health care providers, and (4) ongoing liaison and consultative services for the health care providers. The intervention is intended to encourage HIV risk-reduction behaviors among the patients, to encourage the HIV testing of those who may be at risk for HIV, and to facilitate access to services for those found to be infected.

Repetitive nocturnal arterial oxygen desaturation and silent myocardial ischemia in patients presenting for vascular surgery

OBJECTIVE

To determine whether nocturnal respiratory abnormality (cyclic oxygen desaturation and tachycardia) is associated with nocturnal myocardial ischemia in older individuals with ischemic heart disease.

DESIGN

Non-invasive monitoring on a single occasion.

SETTING

Tertiary care referral hospital.

PATIENTS

Thirty four consecutive older (68.5 +/- 6 yrs) patients referred for elective abdominal or carotid reconstructive vascular surgery.

RESULTS

Seven patients (21%) had moderately severe nocturnal respiratory abnormality, defined by more than 50 dips in arterial oxygen saturation and increases in heart rate during the night. Two of these seven had clinical risk factors for ischemic heart disease and had nocturnal myocardial ischemia. Ten patients (29%) developed ischemia at some time during the study, of whom seven hand known ischemic heart disease, hypertension, and/or angina. Those with increased nocturnal ischemia showed very low frequency (1-2 cycles per minute) cyclic heart rate oscillations and repetitive nocturnal episodes of arterial oxygen desaturation, similar to patients with sleep apnea.

CONCLUSION

Repetitive nocturnal cyclic arterial desaturation and cyclic increases in heart rate are associated with nocturnal myocardial ischemia in individuals with clinical risk factors for ischemic heart disease. Further investigation in a large patient sample utilizing non-invasive monitoring of saturation, heart rate, and blood pressure may provide definitive evidence regarding causation of some of the nocturnal myocardial ischemia occurring in older individuals with vascular disease.

The optimal current direction for excitation of human cervical motor roots with a double coil magnetic stimulator

Upper limb muscles can easily be excited using magnetic stimulation with a circular coil over the cervical vertebrae. Double coil magnetic stimulators generate a more focal and directed form of stimulus and may offer an advantage in the more specific stimulation of individual motor roots. The aims of this study were to determine the optimal rostro-caudal locations and orientations of a double coil magnetic stimulator for excitation of the human 5th cervical to 1st thoracic motor roots. Compound muscle action potentials (CMAPs) evoked by magnetic stimuli were recorded from deltoid, brachioradialis, extensor digitorum communis and first dorsal interosseus muscles. Optimal rostro-caudal location was determined with the coil current flowing horizontally towards the midline. Optimal orientation was determined by rotating the coil in increments of 22.5 degrees about the optimal rostro-caudal location. In all subjects with all muscles examined, the best orientation was with the coil current flowing downwards towards the midline at a mean angle between 14.9 degrees and 27.6 degrees to the horizontal. Review of the anatomy of motor roots reveals a short upwardly directed segment within the intervertebral foramen and it is postulated that excitation occurs exclusively within this segment.

Respiratory involvement in multiple sclerosis

Respiratory complications occur in advanced multiple sclerosis (MS) but may also complicate acute relapses earlier in the disease. We present 19 patients with MS who developed respiratory complications at a mean of 5.9 (range 1-12) yrs after the onset of neurological symptoms. Fourteen patients developed severe respiratory insufficiency presenting with a combination of reduced forced vital capacity (FVC), hypoxaemia or hypercapnia (12 patients) and respiratory arrest (four patients). Two patients presented with apneustic breathing, one with paroxysmal hyperventilation, one with obstructive sleep apnoea and one with bulbar weakness leading to aspiration pneumonia. Respiratory muscle weakness was a major factor in 14 patients (predominantly diaphragm involvement in six), bulbar weakness in seven patients, impaired voluntary control in three and impaired automatic control in three. Twelve patients received mechanical respiratory support of whom seven have subsequently died. The methods of support used were intermittent positive pressure ventilation (nine patients), iron lung (three), cuirass (two) and rocking bed (one). Six patients were maintained on respiratory support until they died after intervals varying from 24 h to 6 yrs (mean 17.7 mths). Five patients received temporary ventilation for between 6 d and 42 d: of these four remain alive at up to 4 yrs and one died after 16 yrs. One patient remains on domiciliary nasal intermittent positive pressure ventilation (IPPV) after 1 yr.

Late postoperative nocturnal dips in oxygen saturation in patients undergoing major abdominal vascular surgery. Predictive value of pre-operative overnight pulse oximetry

Twenty-four patients (23 male) who presented for aortic reconstructive surgery were studied with pulse oximetry on a pre-operative night and during the first five postoperative nights. Patients with five or more dips in oxygen saturation of greater than 4% (with a prompt recovery back toward baseline of 3% or more) per hour of monitoring were classified as having a significant abnormality of respiration. Pre-operatively, four of 24 patients (17%) demonstrated such an abnormality. Postoperatively, 12 patients (50%) met these criteria on at least one of the first five postoperative nights and six of these had two or more nights with severe episodic hypoxaemia. Frequent severe episodic dips in arterial oxygen saturation (to less than 85% saturation) occurred in the late postoperative period at a time when oxygen therapy would usually have been discontinued. Pre-operative overnight pulse oximetry studies fail to predict the development of abnormal respiratory patterns in the postoperative period in the majority of patients.

Postoperative hypoxaemia after major abdominal vascular surgery

We have studied the severity and duration of nocturnal hypoxaemia before operation and for the first five nights after operation after elective major abdominal vascular surgery. Oxygen supplementation was almost 100% effective in keeping oxygen saturation greater than 90% during the early postoperative period; however, 50% of patients spent prolonged periods with an SpO2 less than 85% during at least one night after operation. The risk of severe hypoxaemia persists well beyond the current prescription of supplementary oxygen in these high risk patients. A significant association exists between the mean preoperative overnight saturation value and the nocturnal saturation observed subsequently in the later postoperative period.

Postoperative myocardial ischaemia: temporal association with nocturnal hypoxaemia

Three patients presenting for elective aortic surgery were studied before operation and for up to 3 days after operation with ambulatory electrocardiographic monitoring and nocturnal pulse oximetry. Supplementary oxygen was administered for the first 2 days after operation and withdrawn on the 3rd morning after operation. Heart rate remained increased for the first 3 days after operation. Two patients developed episodes of myocardial ischaemia during the first 48 h after operation while their arterial oxygen saturation remained greater than 90%. On the third day, and during the third night after operation, both the severity and duration of myocardial ischaemia increased markedly, associated with arterial hypoxaemia. A temporal relationship between decreases in oxygen saturation and fluctuations in ST segment level were observed in the three patients.

Postoperative obstructive sleep apnoea. Haemodynamic effects of treatment with nasal CPAP

A 74-year-old man presenting for aortic reconstructive surgery showed severe, previously undiagnosed obstructive sleep apnoea during overnight oximetry monitoring before operation. Postoperatively, in the first 4 hours following extubation, he suffered 238 episodes of respiratory obstruction. These events were associated with frequent arousals, large fluctuations in systolic and diastolic blood pressure. Administration of nasal continuous positive airways pressure abolished the obstructions and allowed an uninterrupted night's sleep, with a significantly reduced blood pressure. Subsequent dips in oxygen saturation as a result of respiratory obstruction recurred on the fifth postoperative night. We conclude that pre-operative overnight oximetry may be useful in identifying those patients at risk of postoperative upper airway obstruction. Use of nasal continuous positive airway pressure may prevent the occurrence of early postoperative obstruction and the associated haemodynamic changes.

Haemodynamic effects of periodic ventilation: abolition with supplementary oxygen

A 63-yr-old man was noted to breathe with a periodic pattern of ventilation during sleep, both before and after operation for coronary artery grafting, and 6 weeks later after aortic aneurysm repair. Periodic ventilation was associated with cyclic oxygen desaturations and increases in heart rate and arterial pressure. Administration of oxygen was found to abolish consistently the periodic pattern and the associated haemodynamic changes.

Recurrent isolated alternating phrenic nerve palsies: a variant of brachial neuritis?

A 40 year old man presented with three episodes of shoulder pain. This is likely to be a variant of brachial neuritis.

Abnormal respiration and sudden death during sleep in multiple system atrophy with autonomic failure

We studied respiration during sleep in 7 patients with multiple system atrophy and autonomic failure (MSA-AF) and 7 control subjects. Although mean respiratory rate, tidal volume, and inspiratory flow rate were statistically similar in both groups, the coefficients of variability in all were significantly greater in MSA-AF patients. Four of 5 nontracheostomized had evidence of upper airway obstruction without significant oxygen desaturation. Three of these 5 patients died suddenly during sleep. MSA-AF is associated with upper airway dysfunction and disordered central respirations which can be life threatening. Evidence of even mild obstruction during sleep should warrant tracheostomy.

Night-time nasal ventilation in neuromuscular disease

14 patients, aged 2-28 years, with neuromuscular disorders and symptomatic sleep hypoventilation received night-time intermittent positive-pressure ventilation with a nasal mask. 9 were treated de novo and 5 had previously been maintained on a cuirass or iron lung. Nasal ventilation was very effective in 10 patients but was not tolerated in 4 of the 5 youngest patients. Nasal ventilation was preferable to other methods of ventilation because the system was non-invasive, quiet, portable, and easy to use and because it allowed considerable independence.

Respiratory complications and their management in motor neuron disease

Although respiratory insufficiency is common in the advanced stages of motor neuron disease, some patients may develop distressing respiratory symptoms early in the course of the disease or even present with respiratory failure or arrest. We describe 14 patients with motor neuron disease who were considered for respiratory support; 11 received such support and all derived significant symptomatic improvement without distressing prolongation of life. Of the 8 patients with typical features of amyotrophic lateral sclerosis, 7 had predominant diaphragm weakness and 1 generalized respiratory muscle weakness; 7 received negative pressure ventilation by cuirass which improved both the quality of sleep and exercise tolerance. Three patients with predominantly bulbar disease had nocturnal apnoea or hypoventilation. Two received no support. One, who also developed diaphragm weakness, was treated by a cuirass, continuous positive airway pressure (CPAP), and later nocturnal intermittent positive pressure ventilation (IPPV). Three patients with progressive muscular atrophy had predominant diaphragm weakness or nocturnal apnoea. These patients received nocturnal CPAP, cuirass or IPPV with symptomatic benefit. This series shows that some patients with motor neuron disease, mainly those with symptoms due to respiratory muscle weakness in the absence of severe bulbar impairment, derive symptomatic benefit from supported ventilation.

Nocturnal hypoventilation in children with nonprogressive neuromuscular disease

Eight patients between 4 and 24 years of age with nonprogressive neuromuscular disease sought medical attention because of severe nocturnal hypoventilation. There were two types of findings: subacute with progressive early morning headaches and daytime drowsiness and acute with ventilatory failure and cor pulmonale. Seven patients were ambulant. Seven were successfully treated with either a cuirass negative pressure ventilator or a positive pressure ventilator via a tracheostomy. The ventilatory assistance was only used at night and resulted in rapid resolution of early morning symptoms and a return to full daytime activity. One patient died as a result of an intercurrent respiratory infection before respiratory support could be given. It is important to be aware of this potentially life-threatening complication in patients with an otherwise good prognosis and of the benefit to be derived from active treatment.