Dynamics of overdose and non-overdose mortality among people living with HIV amidst the illicit drug toxicity crisis in British Columbia

We sought to characterize overdose and non-overdose mortality among PLWH amidst the illicit drug toxicity crisis in British Columbia, Canada. A population-based analysis of PLWH (age ≥19) in British Columbia accessing healthcare from April 1996 to March 2017 was conducted using data from the Seek and Treat for Optimal Prevention of HIV/AIDS (STOP HIV/AIDS) cohort linkage. Underlying causes of deaths were stratified into overdose and non-overdose causes. We compared (bivariate analysis) health-related characteristics and prescription history between PLWH died of overdose and non-overdose causes between April 2009 and March 2017. Among 9,180 PLWH, we observed 962 deaths (142 [14.7%] overdoses; 820 [85.2%] other causes). Compared to those who died from other causes, those who died of overdose were significantly younger (median age [Q, Q3]: 46 years [42, 52] vs. 54 years [48, 63]); had an indication of chronic pain (35.9% vs. 27.1%) and hepatitis C virus (64.8% vs. 50.4%), but fewer experienced hospitalization in the year before death. PLWH who died were most likely to be prescribed with opioids (>50%) and least likely with opioid agonist therapy (<10%) in a year before death. These findings highlight the syndemic of substance use, HCV, and chronic pain, and how the crisis is unqiuely impacting females and younger people.

Impacts of the 2014 severe drought on the Microcystis bloom in San Francisco Estuary

The increased frequency and intensity of drought with climate change may cause an increase in the magnitude and toxicity of freshwater cyanobacteria harmful algal blooms (CHABs), including Microcystis blooms, in San Francisco Estuary, California. As the fourth driest year on record in San Francisco Estuary, the 2014 drought provided an opportunity to directly test the impact of severe drought on cyanobacteria blooms in SFE. A field sampling program was conducted between July and December 2014 to sample a suite of physical, chemical, and biological variables at 10 stations in the freshwater and brackish reaches of the estuary. The 2014 Microcystis bloom had the highest biomass and toxin concentration, earliest initiation, and the longest duration, since the blooms began in 1999. Median chlorophyll a concentration increased by 9 and 12 times over previous dry and wet years, respectively. Total microcystin concentration also exceeded that in previous dry and wet years by a factor of 11 and 65, respectively. Cell abundance determined by quantitative PCR indicated the bloom contained multiple potentially toxic cyanobacteria species, toxic Microcystis and relatively high total cyanobacteria abundance. The bloom was associated with extreme nutrient concentrations, including a 20-year high in soluble reactive phosphorus concentration and low to below detection levels of ammonium. Stable isotope analysis suggested the bloom varied with both inorganic and organic nutrient concentration, and used ammonium as the primary nitrogen source. Water temperature was a primary controlling factor for the bloom and was positively correlated with the increase in both total and toxic Microcystis abundance. In addition, the early initiation and persistence of warm water temperature coincided with the increased intensity and duration of the Microcystis bloom from the usual 3 to 4 months to 8 months. Long residence time was also a primary factor controlling the magnitude and persistence of the bloom, and was created by a 66% to 85% reduction in both the water inflow and diversion of water for agriculture during the summer. We concluded that severe drought conditions can lead to a significant increase in the abundance of Microcystis and other cyanobacteria, as well as their associated toxins.

Using C. elegans Forward and Reverse Genetics to Identify New Compounds with Anthelmintic Activity

Background

The lack of new anthelmintic agents is of growing concern because it affects human health and our food supply, as both livestock and plants are affected. Two principal factors contribute to this problem. First, nematode resistance to anthelmintic drugs is increasing worldwide and second, many effective nematicides pose environmental hazards. In this paper we address this problem by deploying a high throughput screening platform for anthelmintic drug discovery using the nematode Caenorhabditis elegans as a surrogate for infectious nematodes. This method offers the possibility of identifying new anthelmintics in a cost-effective and timely manner.

Methods/Principal findings

Using our high throughput screening platform we have identified 14 new potential anthelmintics by screening more than 26,000 compounds from the Chembridge and Maybridge chemical libraries. Using phylogenetic profiling we identified a subset of the 14 compounds as potential anthelmintics based on the relative sensitivity of C. elegans when compared to yeast and mammalian cells in culture. We showed that a subset of these compounds might employ mechanisms distinct from currently used anthelmintics by testing diverse drug resistant strains of C. elegans. One of these newly identified compounds targets mitochondrial complex II, and we used structural analysis of the target to suggest how differential binding of this compound may account for its different effects in nematodes versus mammalian cells.

Conclusions/Significance

The challenge of anthelmintic drug discovery is exacerbated by several factors; including, 1) the biochemical similarity between host and parasite genomes, 2) the geographic location of parasitic nematodes and 3) the rapid development of resistance. Accordingly, an approach that can screen large compound collections rapidly is required. C. elegans as a surrogate parasite offers the ability to screen compounds rapidly and, equally importantly, with specificity, thus reducing the potential toxicity of these compounds to the host and the environment. We believe this approach will help to replenish the pipeline of potential nematicides.

With over two billion people infected and many billions of dollars of lost crops annually, nematode infections are a serious problem for human health and for agricultural production. While there are drugs to treat infections, many pockets of parasites have been identified worldwide that are developing immunity to the standard treatment regimen. In this study we describe a strategy using the model organism C. elegans as a surrogate parasite to identify several new chemical compounds that may offer additional treatments for infection. We demonstrate how to use our platform to identify compounds that are specific in their effect to nematodes and are not simply biocides. We also show through genetic and molecular analysis in this organism that we can quickly identify the mode of action of any new compound. Most critically, we show that a compound first identified in a free-living nematode, Caenorhabditis elegans, is also effective on a parasitic nematode, Meloidogyne hapla. With this result and considering the level of sequence conservation across much of the nematode phyla we believe our strategy can be more widely applied to find new anthelmintics.

Comparison of empirical continuous positive airway pressure (CPAP) treatment versus initial portable sleep monitoring followed by CPAP treatment for patients with suspected obstructive sleep apnoea

BACKGROUND

Polysomnography is labour-intensive for diagnosing obstructive sleep apnoea (OSA). We compared two algorithms for initiating continuous positive airway pressure (CPAP) treatment for patients with suspected OSA.

METHODS

Symptomatic OSA patients were randomised into either algorithm I or II. Algorithm I consisted of an empirical CPAP trial whereas algorithm II utilised an Apnea Risk Evaluation System, a wireless device applied on the forehead, for establishing a diagnosis before a CPAP trial for 3 weeks. Primary outcome was success of CPAP trial, defined as CPAP usage > 4 h/night and willingness to continue CPAP. Subjective usefulness of CPAP, accuracy of Apnea Risk Evaluation System versus polysomnography and CPAP adherence at 6 months were secondary end-points.

RESULTS

Altogether 138 patients in algorithm I and 110 patients in algorithm II completed the CPAP trial. There were no significant differences between these algorithms with respect to the primary end-point. The sensitivity and specificity of algorithm I versus II as a diagnostic test for OSA were 0.3, 0.8 versus 0.31, 1.00 respectively. In predicting CPAP adherence at 6 months, the likelihood ratio positive for algorithms I and II was 2.7 and 5.27 respectively. The mean (SE) time taken from the first consultation to the end of CPAP trial in algorithm I and algorithm II was 60 (2) and 98 (5) days, respectively, P < 0.01.

CONCLUSION

An ambulatory approach with portable sleep monitoring for diagnosing OSA before a CPAP trial can identify more patients who would adhere to CPAP at 6 months than empirical CPAP treatment alone.

Effects of a randomized maintenance intervention on adiposity and metabolic risk factors in overweight minority adolescents

OBJECTIVE

The objective of this study was to assess the effects of a maintenance programme (monthly newsletters vs. monthly group classes and telephone behavioural sessions) on obesity and metabolic disease risk at 1 year in overweight minority adolescents.

METHODS

After a 4-month nutrition and strength training intervention, 53 overweight Latino and African-American adolescents (15.4 ± 1.1 years) were randomized into one of two maintenance groups for 8 months: monthly newsletters (n = 23) or group classes (n = 30; monthly classes + individualized behavioural telephone sessions). The following outcomes were measured at months 4 (immediately following the intense intervention) and 12: height, weight, blood pressure, body composition via BodPod™ (Life Measurement Instruments, Concord, CA, USA), lipids and glucose/insulin indices via frequently sampled intravenous glucose tolerance test.

RESULTS

There were no significant group by time interactions for any of the health outcomes. There were significant time effects in several outcomes for both groups from months 4 to 12: bench press and leg press decreased by 5% and 14%, respectively (P = 0.004 & P = 0.01), fasting insulin and acute insulin response decreased by 26% and 16%, respectively (P < 0.001 & P = 0.046); while high-density lipoprotein cholesterol and insulin sensitivity improved by 5% and 14% (P = 0.042 & P = 0.039).

CONCLUSIONS

Newsletters as opposed to group classes may suffice as follow-up maintenance programmes to decrease type 2 diabetes and cardiovascular risk in overweight minority adolescents.

Anaesthetic considerations with the metabolic syndrome

The rising incidence of obesity has led to increased prevalence of a distinct, obesity-related metabolic syndrome. This syndrome is characterized by truncal obesity, insulin resistance, altered lipid levels, and hypertension. Definition of the metabolic syndrome rests on a set of clinical criteria instead of a single diagnostic test. It carries a different risk profile than obesity alone, and poses special challenges for the anaesthesiologist. These include preoperative risk stratification for common comorbidities, identifying reasonable thresholds for implementing preoperative risk reduction, overcoming obesity-related issues in intraoperative management, and delivering safe postoperative care. The metabolic syndrome predisposes to coronary artery disease, congestive heart failure, obstructive sleep apnoea, pulmonary dysfunction, and deep venous thrombosis. Because its different presentations can have different risk profiles, anaesthesiologists should assess the cumulative risk of each component of the metabolic syndrome separately, which significantly complicates preoperative management. Since obesity itself is difficult to treat, preoperative risk reduction can be difficult. Few data exist to inform best practice as to the anaesthetic care of patients with metabolic syndrome. This review evaluates and synthesizes current evidence regarding perioperative care for patients with the metabolic syndrome, including indications for preoperative testing; use of aspirin, β-blockers, statins, heparin, and angiotensin-converting enzyme inhibitors; anaesthetic strategies including regional anaesthesia; and postoperative management including continuous positive pressure ventilation by mask, prevention of pulmonary embolism, and indications for advanced respiratory monitoring.

Effects of sleep deprivation and recovery sleep upon cell proliferation in adult rat dentate gyrus

Numerous behavioral and environmental factors modulate the production of new cells in the adult mammalian brain. Although sleep loss has previously been shown to dramatically suppress brain cell proliferation, the effect of recovery sleep after a period of sleep deprivation is not known. Using the disk-over-water paradigm, adult male Sprague-Dawley rats were sleep deprived for 48 h. Separate groups were then allowed either an 8 h period of recovery sleep or an additional 8 h of sleep deprivation. A third group of rats served as a control, and were not sleep deprived. At 54 h, all rats received an injection of 5-bromo-2'-deoxyuridine (200 mg/kg, i.p.) and were killed 2 h later. When compared with control rats, a 36% reduction in cell proliferation was observed in the dentate gyrus of rats subjected to 56 h of sleep deprivation. A similar reduction in proliferation (39%) was observed in rats allowed an 8 h period of recovery sleep. In both deprivation groups, the magnitude of suppression of cell proliferation was approximately twice as large in the posterior hippocampus as it was in the anterior hippocampus. These data confirm previous results that an extended period of sleep deprivation exerts a strong suppressant effect on cell proliferation in the rat dentate gyrus, and demonstrate that this suppression of cell proliferation shows no evidence of recovery for at least 8 h following a 48 h period of sleep deprivation.

Perioperative concerns in sleep apnea

Sleep apnea syndrome is one of a series of sleep-related breathing disorders, and is often under-diagnosed. Recent appreciation of the prevalence of sleep apnea and its physiologic effects has raised patient and caregiver awareness of the disorder. Few definitive data exist to guide perioperative management of patients with sleep apnea. Nevertheless, advances in the study of sleep apnea have served to highlight important aspects of anesthetic care for these patients. An improved understanding of the relationships between sleep apnea and comorbid conditions has better defined the role for preoperative treatment. Recent work has also clarified the impact of interactions between postoperative pain management strategies and sleep apnea, as well as the need for advanced postoperative monitoring. Finally, progress in our understanding of the relationship between sleep deprivation and the anesthesized state may provide new insights into relationships between the anesthetic and sleep states. The present review identifies important perioperative concerns in patients with sleep apnea and suggests management strategies.

Sleep inducing effects of propofol microinjection into the medial preoptic area are blocked by flumazenil

The intravenous anesthetic, propofol, has been shown to increase sleep when microinjected into the medial preoptic area (MPA) of the rat. Similar increases in sleep have also been observed with triazolam, pentobarbital and ethanol microinjection. Together, these findings implicate the MPA as an important anatomic site mediating the effects of sedatives on naturally occurring sleep. Although the molecular mechanism by which propofol in the MPA acts to induce sleep is unclear, potentiating effects on the GABA(A) receptor complex may play a role. To assess this possibility, we microinjected propofol alone, and in combination with the benzodiazepine receptor antagonist flumazenil, into the MPA. At a dose of 0.76 microg, flumazenil had no effect on sleep when given alone, and completely blocked the increase in sleep caused by a 40-ng dose of propofol although it did not affect the increase in sleep caused by an 80-ng dose of propofol. These data suggest that the sleep inducing property of propofol is in part mediated by direct or indirect actions on the GABA(A)-benzodiazepine receptor complex.

The hypnotic effect of propofol in the medial preoptic area of the rat

Recent introduction of the intravenous anesthetic propofol as an ICU sedative has allowed a deeply sedated state to be maintained for extended periods in the ICU without delays in emergence. Although such sedation has been advocated to promote physiologic sleep, little evidence exists to support such a strategy. To explore propofol's effect on sleep regulation, we administered propofol directly into the medial preoptic area (MPA) of the rat, an anatomic site where administration of other sedatives (triazolam and phenobarbital) also induce sleep. We performed three two-hour sleep studies in the daytime with the lights on following the administration of propofol (8 ng or 40 ng) or vehicle (intralipid). The higher dose of propofol significantly reduced sleep latency and increased nonREM and total sleep times when compared to vehicle. REM sleep times, intermittent waking times and number of transitions were not altered. Mean nonREM sleep bout length was increased significantly at the higher dose. These findings suggest that propofol may enhance sleep by acting at a hypothalamic site.

Prolonged sedation with propofol in the rat does not result in sleep deprivation

The use of propofol provides sedation without prolonging emergence in patients in the Intensive Care Unit. When prolonged, however, continuous sedation may overlap with naturally occurring sleep periods and potentially increase the risk of sleep deprivation. We modified an established rat model of sleep to determine whether prolonged, continuous sedation results in sleep deprivation. Rats were continuously sedated for a 12-h period overlapping completely with their normal sleep phase. Electroencephalogram (EEG) and movement data were collected before and after the sedation period. Rats were evaluated for EEG and movement evidence of sleep deprivation after sedation. When compared with baseline, the time spent in rapid eye movement (REM) and non-REM sleep was decreased during the first 4 h after sedation. The duration of non-REM sleep bouts was not altered. Power in the delta band (0.5-4 Hz) during non-REM sleep was diminished during the first 2 h only. Movements were reduced during the first hour after emergence from sedation only. In summary, no EEG or behavioral evidence of sleep deprivation was observed on emergence from sedation. These results imply that sedation is associated with a restorative process reversing the natural accumulation of sleep need that occurs during wakefulness.

IMPLICATIONS

Prolonged sedation in the Intensive Care Unit may alter the restorative effects of naturally occurring sleep. We sedated rats during their sleep phase to determine whether sedation interferes with sleep. Upon emergence, no evidence of sleep deprivation was observed. Sedation may thus be associated with a restorative effect similar to sleep.

BIS Monitoring to Prevent Awareness during General Anesthesia

Background

Unexpected awareness is a rare but well-described complication of general anesthesia that has received increased scientific and media attention in the past few years. Transformed electroencephalogram monitors, such as the Bispectral Index monitor, have been advocated as tools to prevent unexpected recall.

Methods

The authors conducted a power analysis to estimate how many patients would be needed in an appropriately powered study to demonstrate the Bispectral Index monitor reduces awareness, as well as a cost analysis to assess the cost of using the monitor for this purpose alone.

Results

If unexpected recall is rare (1 in 20,000), it will require a large study to demonstrate that the monitor reduces awareness (200,000-800,000 patients), and the cost of using it for this purpose alone would be high ($400,000 per case prevented). If awareness is common (1 in 100), then the number of patients needed in a study to demonstrate that the monitor works becomes tractable (1,000-4,000 patients), and the cost of using the monitor for this purpose alone becomes lower ($2,000 per case prevented). Because there are reported cases of awareness despite Bispectral Index monitoring, the authors are certain that the effectiveness of the monitor is less than 100%. As the performance of the monitor decreases from 100%, the size of the study needed to demonstrate that it works increases, as does the cost of using it to prevent awareness.

Conclusion

The contention that Bispectral Index monitoring reduces the risk of awareness is unproven, and the cost of using it for this indication is currently unknown.

The relationship of sedation to deliberate self-extubation

STUDY OBJECTIVES

To evaluate the relationship between sedative therapy and self-extubation in a large medical-surgical intensive care unit (ICU).

DESIGN

Retrospective, case-controlled study.

SETTING

Large teaching hospital.

PATIENTS

All adult patients who underwent unplanned self-extubation during a 12-month period (n = 50). Each patient was matched to two control patients who did not self-extubate based on age, gender, dates in hospital and diagnosis.

INTERVENTIONS

none.

MEASUREMENTS

Data collected included time to self extubation, dosages and types of benzodiazepines, opioid analgesics, antipsychotics, and hypnotics. Data on the degree of agitation as assessed by nursing staff also were obtained.

MAIN RESULTS

When compared to controls, patients in the self-extubation group were more likely to have received benzodiazepines (59% vs. 35%; p < 0.05), but equally likely to have received opioids and/or paralytic drugs. Patients who self-extubated were twice as likely as controls to be agitated (54% vs. 22%; p < 0.05). Use of benzodiazepines was more common in agitated patients than in nonagitated patients (62% vs. 35%; p < 0.02). Among nonagitated patients who self-extubated, increased use of benzodiazepines (57% vs. 29%; p < 0.05) was noted when compared to nonagitated controls.

CONCLUSIONS

In intubated ICU patients, benzodiazepines may not consistently treat agitation effectively or prevent self-extubation. Such an effect may be due to paradoxical excitation, disorientation during long-term administration, or differences in drug administration between ICU and operating room (OR) environments.

A new biological assay for measuring cyanide in blood

Clinical diagnosis of cyanide poisoning is complicated by the lack of an easy, convenient assay for cyanide concentration in blood. Therapy may be delayed with unconfirmed diagnosis because the conventional antidote to cyanide poisoning exposes patients to substantial risks. We developed a new spectrophotometric assay to measure cyanide by extraction into a sodium hydroxide trap, followed by the addition of exogenous methemoglobin as a colormetric indicator. Samples of blood from 15 healthy subjects and 5 patients who had received prolonged nitroprusside infusions were assayed. To optimize assay characteristics, methemoglobin concentrations, pH, temperature, incubation time, and buffer strengths were varied. Duplicate samples were assayed by using the polarographic method for assay validation. Over a range from 300 ng/mL to 7 microg/mL, the correlation between methods was r = 0.983. Interassay and intraassay variability were 5% and 2%, respectively. Samples drawn from the five patients and tested by using both methods yielded a correlation of r = 0.978. This new assay for cyanide in blood may greatly facilitate the diagnosis and treatment of cyanide ingestion. The use of methemoglobin as the colorimetric indicator in the assay contributes to its low cost and ease of use.

IMPLICATIONS

Cyanide, an important factor in death from burn-related inhalation injury, is difficult and time-consuming to measure. We developed a new, rapid blood test for cyanide using methemoglobin as a colormetric indicator. A rapid, accessible test for cyanide may speed the diagnosis and treatment of cyanide poisoning.

Indications for mechanical ventilation

Indications for mechanical ventilation have evolved substantially since widespread use of ventilatory support began in the early 1960s. While the metabolic and blood-gas alterations that mandate institution of ventilatory support have remained unaltered, new noninvasive modes of ventilation have widened the therapeutic options available to patients in acute respiratory failure. An understanding of the effect of mechanical ventilation on other organ systems has clarified the role of mechanical ventilation in the treatment of conditions other than respiratory failure such as stroke or head injury. Studies in patients recovering from major surgery have better defined the benefits and risks of postoperative mechanical ventilation. Finally, a better understanding of disease processes has led to more prognostic information that can help physicians, patients, and families decide on limits to compassionate care. The proper use of mechanical ventilation in disease states that do not involve respiratory failure as their primary manifestation is also important in light of the risks of respiratory support. In patients with CNS injury, the role of hyperventilation is limited to acute control of dangerous elevations of intracranial pressure. Although hypocarbia has been proposed to improve regional cerebral blood flow, studies have not demonstrated an improvement in outcome, suggesting that the risks of intubation, tracheal stimulation, sedation, and inability to examine the mental status outweigh any benefit. Some evidence suggests a detrimental effect from prolonged hyperventilation. The use of mechanical ventilation in postoperative care is another area that requires scrutiny. Numerous studies have shown that with coordination of care between surgeons, anesthesiologists, and nurses, many patients can be extubated significantly sooner than in the past. As techniques for administering anesthesia, performing surgery, and managing pain and mild respiratory insufficiency improve, knowledge in this area will continue to develop. Finally, the relation between mechanical ventilation, quality of life, and patient autonomy has come to play a greater role as the population ages. In many situations, respiratory failure represents the end stage of an irreversible disease. Whereas respiratory failure secondary to pulmonary contusion in young patients does not indicate a poor outcome, progressive respiratory failure in cystic fibrosis or following bone marrow transplantation usually represents a preterminal event. Understanding the epidemiology of respiratory failure in different disease categories is important to physicians, patients, and families in making informed decisions about their care. Mechanical ventilation represents a vital, fundamental form of life support. As the diseases, tools, and treatments change in anesthesia and critical care, careful definition of the role of mechanical ventilation in specific diseases, the route by which it is delivered, and the ability of such a form of life support to affect outcome will continue to be necessary.

Patients requiring sedation

Recent advances in the pharmacology of sedative drugs have expanded their use in the intensive care unit. Indications and endpoints for sedation, however, often are defined poorly and are difficult to assess. Nevertheless, the complications of sedative drug administration are real. New indications for sedation have been proposed in recent years, including enforcing sleep/wake cycles, manipulating cellular metabolism, and preventing myocardial ischemia. The evidence supporting the efficacy of these new indications is not yet complete.

Acute and chronic effects of intrathecal morphine in monkeys

In a double-blind study, seven Macaca fascicularis monkeys receiving intrathecal (i.t.) morphine in saline, 0.07 mg kg-1, were compared with a control group of four monkeys receiving either lumbar puncture alone (n = 1) or i.t. saline (n = 3). Neither morphine nor saline solutions contained preservatives. Arterial blood gas tensions, respiration, arterial pressure, e.c.g., state of consciousness and motor function were recorded for 24 h. The control group was sacrificed 42 days later and the study group was sacrificed at 6 (n = 2) or 42 days (n = 5) after injection. The central nervous system, meninges, nerve roots and dorsal root ganglia were examined macroscopically and microscopically. Respiratory depression did not occur in either the control or the study groups. There were moderate but statistically significant decreases in systolic and diastolic arterial pressures following i.t. morphine. In both groups, the pathological findings were localized to the cauda equina region and characterized by mononuclear cell infiltration. In neither group was there evidence of demyelination, arachnoiditis or necrosis. Focal endoneurial fibrosis was found in only one animal in the control group following multiple lumbar punctures associated with paraesthesia. The features appeared to correlate with the physical trauma associated with lumbar puncture rather than with the injectate.

Use of air bubble illuminator as an adjunct for surgery in the sitting position

The use and construction of a simple device to illuminate air bubbles in an intravenous tubing connected to the right atrial catheter when air embolism is suspected is described. This had been effective in clearly demonstrating even small air bubbles in more than 25 cases.