Thirst-guided participant-controlled intravenous fluid rehydration: a single blind, randomised crossover study.

BACKGROUND: Dehydration is common in hospitals and is associated with increased mortality and morbidity. Clinical assessment and diagnostic measures of dehydration are unreliable. We sought to investigate the novel concept that individuals might control their own intravenous rehydration, guided by thirst. METHODS: We performed a single-blind, counterbalanced, randomised cross-over trial. Ten healthy male volunteers of mean age 26 (standard deviation [sd] 10.5) yr were dehydrated by 3-5% of their baseline body mass via exercising in the heat (35°C, 60% humidity). This was followed by a 4 h participant-controlled intravenous rehydration: individuals triggered up to six fluid boluses (4% dextrose in 0.18% sodium chloride) per hour in response to thirst. Participants undertook two blinded rehydration protocols which differed only by bolus volume: 50 ml (low volume [LV]) or 200 ml (high volume [HV]). Each hour during the rehydration phase, plasma osmolality (pOsm) was measured and thirst score recorded. Nude body mass was measured at baseline, after dehydration, and after the rehydration phase. RESULTS: In both conditions, the mean dehydration-related body mass loss was 3.9%. Thirst score was strongly associated with pOsm (within-subject r=0.74) and demand for fluid decreased as pOsm corrected. In the HV condition, participants rapidly rehydrated themselves (mean fluid delivered 3060 vs 981 ml in the LV condition) to body mass and pOsm no different to their euhydrated state. CONCLUSION: Healthy individuals appear able to rely on thirst to manage intravenous fluid intake. Future work must now focus on whether patient-controlled intravenous fluids could represent a paradigm shift in the management of hydration in the clinical setting. CLINICAL TRIAL REGISTRATION: NCT03932890.

Perioperative Quality Initiative consensus statement on preoperative blood pressure, risk and outcomes for elective surgery.

BACKGROUND: A multidisciplinary international working subgroup of the third Perioperative Quality Initiative consensus meeting appraised the evidence on the influence of preoperative arterial blood pressure and community cardiovascular medications on perioperative risk. METHODS: A modified Delphi technique was used, evaluating papers published in MEDLINE on associations between preoperative numerical arterial pressure values or cardiovascular medications and perioperative outcomes. The strength of the recommendations was graded by National Institute for Health and Care Excellence guidelines. RESULTS: Significant heterogeneity in study design, including arterial pressure measures and perioperative outcomes, hampered the comparison of studies. Nonetheless, consensus recommendations were that (i) preoperative arterial pressure measures may be used to define targets for perioperative management; (ii) elective surgery should not be cancelled based solely upon a preoperative arterial pressure value; (iii) there is insufficient evidence to support lowering arterial pressure in the immediate preoperative period to minimise perioperative risk; and (iv) there is insufficient evidence that any one measure of arterial pressure (systolic, diastolic, mean, or pulse) is better than any other for risk prediction of adverse perioperative events. CONCLUSIONS: Future research should define which preoperative arterial pressure values best correlate with adverse outcomes, and whether modifying arterial pressure in the preoperative setting will change the perioperative morbidity or mortality. Additional research should define optimum strategies for continuation or discontinuation of preoperative cardiovascular medications.

Learning to treat the climate emergency together: social tipping interventions by the health community.

Accelerating the decarbonisation of local and national economies is a profound public health imperative. As trusted voices within communities around the world, health professionals and health organisations have enormous potential to influence the social and policy landscape in support of decarbonisation. We assembled a multidisciplinary, gender-balanced group of experts from six continents to develop a framework for maximising the social and policy influence of the health community on decarbonisation at the micro levels, meso levels, and macro levels of society. We identify practical, learning-by-doing approaches and networks to implement this strategic framework. Collectively, the actions of health-care workers can shift practice, finance, and power in ways that can transform the public narrative and influence investment, activate socioeconomic tipping points, and catalyse the rapid decarbonisation needed to protect health and health systems.

Clustering of Environmental Parameters and the Risk of Acute Myocardial Infarction.

The association between days with similar environmental parameters and cardiovascular events is unknown. We investigate the association between clusters of environmental parameters and acute myocardial infarction (AMI) risk in Singapore. Using k-means clustering and conditional Poisson models, we grouped calendar days from 2010 to 2015 based on rainfall, temperature, wind speed and the Pollutant Standards Index (PSI) and compared the incidence rate ratios (IRR) of AMI across the clusters using a time-stratified case-crossover design. Three distinct clusters were formed with Cluster 1 having high wind speed, Cluster 2 high rainfall, and Cluster 3 high temperature and PSI. Compared to Cluster 1, Cluster 3 had a higher AMI incidence with IRR 1.04 (95% confidence interval 1.01-1.07), but no significant difference was found between Cluster 1 and Cluster 2. Subgroup analyses showed that increased AMI incidence was significant only among those with age ≥65, male, non-smokers, non-ST elevation AMI (NSTEMI), history of hyperlipidemia and no history of ischemic heart disease, diabetes or hypertension. In conclusion, we found that AMI incidence, especially NSTEMI, is likely to be higher on days with high temperature and PSI. These findings have public health implications for AMI prevention and emergency health services delivery during the seasonal Southeast Asian transboundary haze.

AlzEye: longitudinal record-level linkage of ophthalmic imaging and hospital admissions of 353 157 patients in London, UK.

PURPOSE: Retinal signatures of systemic disease ('oculomics') are increasingly being revealed through a combination of high-resolution ophthalmic imaging and sophisticated modelling strategies. Progress is currently limited not mainly by technical issues, but by the lack of large labelled datasets, a sine qua non for deep learning. Such data are derived from prospective epidemiological studies, in which retinal imaging is typically unimodal, cross-sectional, of modest number and relates to cohorts, which are not enriched with subpopulations of interest, such as those with systemic disease. We thus linked longitudinal multimodal retinal imaging from routinely collected National Health Service (NHS) data with systemic disease data from hospital admissions using a privacy-by-design third-party linkage approach. PARTICIPANTS: Between 1 January 2008 and 1 April 2018, 353 157 participants aged 40 years or older, who attended Moorfields Eye Hospital NHS Foundation Trust, a tertiary ophthalmic institution incorporating a principal central site, four district hubs and five satellite clinics in and around London, UK serving a catchment population of approximately six million people. FINDINGS TO DATE: Among the 353 157 individuals, 186 651 had a total of 1 337 711 Hospital Episode Statistics admitted patient care episodes. Systemic diagnoses recorded at these episodes include 12 022 patients with myocardial infarction, 11 735 with all-cause stroke and 13 363 with all-cause dementia. A total of 6 261 931 retinal images of seven different modalities and across three manufacturers were acquired from 1 54 830 patients. The majority of retinal images were retinal photographs (n=1 874 175) followed by optical coherence tomography (n=1 567 358). FUTURE PLANS: AlzEye combines the world's largest single institution retinal imaging database with nationally collected systemic data to create an exceptional large-scale, enriched cohort that reflects the diversity of the population served. First analyses will address cardiovascular diseases and dementia, with a view to identifying hidden retinal signatures that may lead to earlier detection and risk management of these life-threatening conditions.

A multidisciplinary consensus on dehydration: definitions, diagnostic methods and clinical implications.

Background: Dehydration appears prevalent, costly and associated with adverse outcomes. We sought to generate consensus on such key issues and elucidate need for further scientific enquiry. Materials and methods: A modified Delphi process combined expert opinion and evidence appraisal. Twelve relevant experts addressed dehydration's definition, objective markers and impact on physiology and outcome. Results: Fifteen consensus statements and seven research recommendations were generated. Key findings, evidenced in detail, were that there is no universally accepted definition for dehydration; hydration assessment is complex and requires combining physiological and laboratory variables; "dehydration" and "hypovolaemia" are incorrectly used interchangeably; abnormal hydration status includes relative and/or absolute abnormalities in body water and serum/plasma osmolality (pOsm); raised pOsm usually indicates dehydration; direct measurement of pOsm is the gold standard for determining dehydration; pOsm >300 and ≤280 mOsm/kg classifies a person as hyper or hypo-osmolar; outside extremes, signs of adult dehydration are subtle and unreliable; dehydration is common in hospitals and care homes and associated with poorer outcomes. Discussion: Dehydration poses risk to public health. Dehydration is under-recognized and poorly managed in hospital and community-based care. Further research is required to improve assessment and management of dehydration and the authors have made recommendations to focus academic endeavours. Key messages Dehydration assessment is a major clinical challenge due to a complex, varying pathophysiology, non-specific clinical presentations and the lack of international consensus on definition and diagnosis. Plasma osmolality represents a valuable, objective surrogate marker of hypertonic dehydration which is underutilized in clinical practice. Dehydration is prevalent within the healthcare setting and in the community, and appears associated with increased morbidity and mortality.

The sensitivity of the human thirst response to changes in plasma osmolality: a systematic review.

BACKGROUND: Dehydration is highly prevalent and is associated with adverse cardiovascular and renal events. Clinical assessment of dehydration lacks sensitivity. Perhaps a patient's thirst can provide an accurate guide to fluid therapy. This systematic review examines the sensitivity of thirst in responding to changes in plasma osmolality in participants of any age with no condition directly effecting their sense of thirst. METHODS: Medline and EMBASE were searched up to June 2017. Inclusion criteria were all studies reporting the plasma osmolality threshold for the sensation of thirst. RESULTS: A total of 12 trials were included that assessed thirst intensity on a visual analogue scale, as a function of plasma osmolality (pOsm), and employed linear regression to define the thirst threshold. This included 167 participants, both healthy controls and those with a range of pathologies, with a mean age of 41 (20-78) years.The value ±95% CI for the pOsm threshold for thirst sensation was found to be 285.23 ± 1.29 mOsm/kg. Above this threshold, thirst intensity as a function of pOsm had a mean ± SEM slope of 0.54 ± 0.07 cm/mOsm/kg. The mean ± 95% CI vasopressin release threshold was very similar to that of thirst, being 284.3 ± 0.71 mOsm/kg.Heterogeneity across studies can be accounted for by subtle variation in experimental protocol and data handling. CONCLUSION: The thresholds for thirst activation and vasopressin release lie in the middle of the normal range of plasma osmolality. Thirst increases linearly as pOsm rises. Thus, osmotically balanced fluid administered as per a patient's sensation of thirst should result in a plasma osmolality within the normal range. This work received no funding.

Objective Assessment of Patient Inhaler User Technique Using an Audio-Based Classification Approach.

Many patients make critical user technique errors when using pressurised metered dose inhalers (pMDIs) which reduce the clinical efficacy of respiratory medication. Such critical errors include poor actuation coordination (poor timing of medication release during inhalation) and inhaling too fast (peak inspiratory flow rate over 90 L/min). Here, we present a novel audio-based method that objectively assesses patient pMDI user technique. The Inhaler Compliance Assessment device was employed to record inhaler audio signals from 62 respiratory patients as they used a pMDI with an In-Check Flo-Tone device attached to the inhaler mouthpiece. Using a quadratic discriminant analysis approach, the audio-based method generated a total frame-by-frame accuracy of 88.2% in classifying sound events (actuation, inhalation and exhalation). The audio-based method estimated the peak inspiratory flow rate and volume of inhalations with an accuracy of 88.2% and 83.94% respectively. It was detected that 89% of patients made at least one critical user technique error even after tuition from an expert clinical reviewer. This method provides a more clinically accurate assessment of patient inhaler user technique than standard checklist methods.

Persistent pseudomyopia following a whiplash injury in a previously emmetropic woman.

PURPOSE: Accommodative spasm, which manifests as ciliary muscle spasm, convergent strabismus or miosis, is a recognised consequence of head trauma. In whiplash cases, cervical spine hyperextension poses a risk of contra-coup injury and brainstem trauma, and is known to affect the visual system. However, to date, no cases of accommodative spasm due to whiplash injury have been reported. OBSERVATIONS: We present the case of a 34-year-old female who developed sudden onset blurred distance vision after a rear impact car crash, having previously been emmetropic. Her unaided distance visual acuity was 20/70 in the right eye and 20/20 in the left. Best-corrected visual acuity in the right eye was 20/20 with a correction that progressed from -1.75 to -3.50 DS over the 12 months following the accident.This patient's sudden unilateral myopia, with unilaterally increased amplitude of accommodation suggests pseudomyopia due to accommodative spasm. Magnetic resonance imaging showed no evidence of injury to her brain stem, frontal lobes or oculomotor nerve. The patient is now well adjusted with a -3.50DS corrective lens for the right eye. CONCLUSIONS AND IMPORTANCE: The accommodation reflex is susceptible to injury at the occipital lobe, frontal eye fields, Edinger-Westphal nuclei and oculomotor nerves. As such it should be examined in patients who present with visual disturbances following whiplash injury.It is important that such cases are identified at presentation, as early intervention can improve outcomes in accommodative spasm and reduce the long term psychological effects often associated with whiplash injuries.