Patient and surgery factors associated with the incidence of failed and difficult intubation.

Estimates of the rate and risk-factors for difficult airway rarely include a denominator for the number of anaesthetics. Approaches such as self-reporting and crowd-sourcing of airway incidents may help identify specific lessons from clinical episodes, but the lack of denominator data, biased reporting and under-reporting does not allow a comprehensive population-based assessment. We used an established state-wide dataset to determine the incidence of failed and difficult intubations between 2015 and 2017 in the state of Victoria in Australia, along with associated patient and surgical risk-factors. A total of 861,533 general anaesthesia episodes were analysed. Of these, 4092 patients with difficult or failed intubation were identified; incidence rates of 0.52% (2015-2016) and 0.43% (2016-2017), respectively. Difficult/failed intubations were most common in patients aged 45-75 and decreased for older age groups, with risk being lower for patients aged >85 than patients aged 35-44. The risk for failed/difficult intubation increased significantly for: patients undergoing emergency surgery (OR 1.80); obese patients (OR 2.48); increased ASA physical status; and increased Charlson Comorbidity Index. Across all age groups, procedures on the nervous system (OR 1.92) and endocrine system (OR 2.03) had the highest risk of failed/difficult intubation. The relative reduced risk for failed/difficult intubations in the elderly population is a novel finding that contrasts with previous research and may suggest a 'compression of morbidity' effect as a moderator. Administrative databases have the potential to improve understanding of peri-operative risk of rare events at a population level.

Examining physiological responses across different driving maneuvers during an on-road driving task: a pilot study comparing older and younger drivers.

OBJECTIVE: This pilot study aimed to investigate physiological responses during an on-road driving task for older and younger drivers. METHODS: Five older drivers (mean age = 74.60 years [2.97]) and 5 younger drivers (mean age = 30.00 years [3.08]) completed a series of cognitive assessments (Montreal Cognitive Assessment [MoCA], Mini Mental Status Examination [MMSE]; Trail Making Test [Trails A and Trails B]) and an on-road driving task along a predetermined, standardized urban route in their own vehicle. Driving performance was observed and scored by a single trained observer using a standardized procedure, where driving behaviors (appropriate and inappropriate) were scored for intersection negotiation, lane changing, and merging. During the on-road driving task, participants' heart rate (HR) was monitored with an unobtrusive physiological monitor. RESULTS: Younger drivers performed significantly better on all cognitive assessments compared to older drivers (MoCA: t(8) = 3.882, P <.01; MMSE: t(8) = 2.954, P <.05; Trails A: t(8) = -2.499, P <.05; Trails B: t(8) = -3.262, P <.05). Analyses of participants' performance during the on-road driving task revealed a high level of appropriate overall driving behavior (M = 87%, SD = 7.62, range = 73-95%), including intersection negotiation (M = 89%, SD = 8.37%), lane changing (M = 100%), and merging (M = 53%, SD = 28.28%). The overall proportion of appropriate driving behavior did not significantly differ across age groups (younger drivers: M = 87.6%, SD = 9.04; older drivers: M = 87.0%, SD = 6.96; t(8) = 0.118, P =.91). CONCLUSIONS: Although older drivers scored lower than younger drivers on the cognitive assessments, there was no indication of cognitive overload among older drivers based on HR response to the on-road driving task. The results provide preliminary evidence that mild age-related cognitive impairment may not pose a motor vehicle crash hazard for the wider older driver population. To maintain safe mobility of the aging population, further research into the specific crash risk factors in the older driver population is warranted.

Age, occupational demands and the risk of serious work injury.

BACKGROUND: Interest in the relationship between age and serious work injury is increasing, given the ageing of the workforce in many industrialized economies. AIMS: To examine if the relationship between age and risk of serious musculoskeletal injury differs when the physical demands of work are higher from those when they are lower. METHODS: A secondary analysis of workers' compensation claims in the State of Victoria, Australia, combined with estimates of the insured labour force. We focused on musculoskeletal claims, which required 10 days of absence or health care expenditures beyond a pecuniary threshold. Regression models examined the relationship between age and claim-risk across workers with different occupational demands, as well as the relationship between occupational demands and musculoskeletal claim-risk across different age groups. RESULTS: Older age and greater physical demands at work were associated with an increased risk of musculoskeletal claims. In models stratified by occupational demands, we observed the relationship between age and claim-risk was steeper when occupational demands were higher. We also observed that the relationship between occupational demands and risk of work injury claim peaked among workers aged 25-44, attenuating among those aged 45 and older. CONCLUSIONS: This study's results suggest that although older workers and occupations with higher demands should be the targets of primary preventive efforts related to serious musculoskeletal injuries, there may also be gains in targeting middle-aged workers in the most physically demanding occupations.

Guideline adherence for empirical treatment of pneumonia and patient outcome. Treating pneumonia in the Netherlands.

INTRODUCTION: According to the Dutch guidelines, severity of community acquired pneumonia (CAP) (mild, moderate-severe, severe) should be based on either PSI, CURB65 or a 'pragmatic' classification. In the last mentioned, the type of ward of admission, as decided by the treating physician, is used as classifier: no hospital admission is mild, admission to a general ward is moderate-severe and admission to an intensive care unit (ICU) is severe CAP. Empiric antibiotic recommendations for each severity class are uniform. We investigated, in 23 hospitals, which of the three classification systems empirical treatment of CAP best adhered to, and whether a too narrow spectrum coverage (according to each of the systems) was associated with a poor patient outcome (in-hospital mortality or need for ICU admission). PATIENTS AND METHODS: Prospective observational study in 23 hospitals. RESULTS: 271 (26%) of 1047 patients with CAP confirmed by X-ray were categorised in the same severity class with all three classification methods. Proportions of patients receiving guideline-adherent antibiotics were 62.9% (95% CI 60.0-65.8%) for the pragmatic, 43.1% (95% CI 40.1-46.1%) for PSI and 30.5% (95% CI 27.8-33.3%) for CURB65 classification. 'Under-treatment' based on the pragmatic classification was associated with a trend towards poor clinical outcome, but no such trend was apparent for the other two scoring systems. CONCLUSIONS: Concordance between three CAP severity classification systems was low, implying large heterogeneity in antibiotic treatment for CAP patients. Empirical treatment appeared most adherent to the pragmatic classification. Non-adherence to treatment recommendations based on the PSI and CURB65 was not associated with a poor clinical outcome.

Fibroblast growth factor 23 in hypophosphataemic HIV-positive adults on tenofovir.

OBJECTIVES: Hypophosphataemia is common in HIV-positive patients, in particular in those using tenofovir disoproxil fumarate (TDF). Its pathogenesis is not well understood. The importance of fibroblast growth factor 23 (FGF-23), the most potent phosphaturic hormone known today, has not been studied in these patients. The aim of the study was to investigate whether FGF-23 might be involved in the aetiology of hypophosphataemia in HIV-positive patients on tenofovir. METHODS: Calcium and phosphate metabolism was studied in 36 HIV-positive patients on TDF. Hypophosphataemia was defined as a serum phosphate level<0.75 mmol/L. RESULTS: Fifteen patients (42%) had hypophosphataemia (group 1), and 21 had a normal serum phosphate level (group 2). The renal phosphate reabsorption threshold [tubular maximum phosphate reabsorption per glomerular filtration rate (TmP/gfr)] was significantly lower in group 1 than in group 2 (0.58 ± 0.04 vs. 0.91 ± 0.03 mmol/L, respectively; P<0.0001). The serum phosphate concentration was strongly correlated with TmP/gfr (R=0.71; P<0.0001). Both groups had normal serum FGF-23 levels, and serum phosphate and TmP/gfr were not related to serum parathyroid hormone (PTH) or FGF-23 levels. CONCLUSION: FGF-23 is not involved in the pathogenesis of hypophosphataemia in HIV-positive patients on TDF. The data suggest that a PTH-like factor may be involved.

Height loss in elderly women is preceded by osteoporosis and is associated with digestive problems and urinary incontinence.

SUMMARY: This study explores risk factors for height loss and consequences in terms of health and wellbeing, in older women. Osteoporosis, low body-mass index, being born in Europe and using medications for both sleep and anxiety were risk factors for height loss. Height loss was associated with digestive problems; excessive height loss was also associated with urinary stress-incontinence and a decline in self-rated health. INTRODUCTION: Height loss is associated with osteoporosis, but little is known about its consequences. We aimed to examine the risk factors for height loss and the symptoms associated with height loss. METHODS: Elderly participants of the Australian Longitudinal Study on Women's Health (aged 70-75 in 1996) who provided data on height at any two consecutive surveys (held in 1996, 1999, 2002, and 2005) were included (N = 9,852). A regression model was fitted with height loss as the outcome and sociodemographics, osteoporosis, and other risk factors as explanatory variables. Symptoms related to postural changes or raised intra-abdominal pressure were analyzed using height loss as an explanatory variable. RESULTS: Over 9 years, average height loss per year was -0.12% (95% confidence intervals [95% CI] = -0.13 to -0.12) of height at baseline. Height loss was greater among those with osteoporosis and low body mass index and those taking medications for sleep and anxiety. After adjusting for confounders, symptoms associated with height loss of > or =2% were heartburn/indigestion (odds ratio [OR] = 1.19, 95% CI = 1.01 to 1.40), constipation (OR = 1.18, 95% CI = 1.01 to 1.37), and urinary stress incontinence (OR = 1.20, 95% CI = 1.02 to 1.41). CONCLUSION: These findings highlight the importance of monitoring height among the elderly in general practice and targeting associated symptoms.

Mathematical modeling of gravitational effects on the circulation: importance of the time course of venous pooling and blood volume changes in the lungs.

A dip in blood pressure (BP) in response to head-up tilt (HUT) or active standing might be due to rapid pooling in the veins below the heart (preload) or muscle activation-induced drop in systemic vascular resistance (afterload). We hypothesized that, in the cardiovascular response to passive HUT, where, in contrast to active standing, little BP dip is observed, features affecting the preload play a key role. We developed a baroreflex model combined with a lumped-parameter model of the circulation, including viscoelastic stress-relaxation of the systemic veins. Cardiac contraction is modeled using the varying-elastance concept. Gravity affects not only the systemic, but also the pulmonary, circulation. In accordance with the experimental results, model simulations do not show a BP dip on HUT; the tilt-back response is also realistic. If it is assumed that venous capacities are steady-state values, the introduction of stress-relaxation initially reduces venous pooling. The resulting time course of venous pooling is comparable to measured impedance changes. When venous pressure-volume dynamics are neglected, rapid (completed within 30 s) venous pooling leads to a drop in BP. The direct effect of gravity on the pulmonary circulation influences the BP response in the first approximately 5 s after HUT and tilt back. In conclusion, the initial BP response to HUT is mainly determined by the response of the venous system. The time course of lower body pooling is essential in understanding the response to passive HUT.

Orthostatic blood pressure control before and after spaceflight, determined by time-domain baroreflex method.

Reduction in plasma volume is a major contributor to orthostatic tachycardia and hypotension after spaceflight. We set out to determine time- and frequency-domain baroreflex (BRS) function during preflight baseline and venous occlusion and postflight orthostatic stress, testing the hypothesis that a reduction in central blood volume could mimic the postflight orthostatic response. In five cosmonauts, we measured finger arterial pressure noninvasively in supine and upright positions. Preflight measurements were repeated using venous occlusion thigh cuffs to impede venous return and "trap" an increased blood volume in the lower extremities; postflight sessions were between 1 and 3 days after return from 10- to 11-day spaceflight. BRS was determined by spectral analysis and by PRVXBRS, a time-domain BRS computation method. Although all completed the stand tests, two of five cosmonauts had drastically reduced pulse pressures and an increase in heart rate of approximately 30 beats/min or more during standing after spaceflight. Averaged for all five subjects in standing position, high-frequency interbeat interval spectral power or transfer gain did not decrease postflight. Low-frequency gain decreased from 8.1 (SD 4.0) preflight baseline to 6.8 (SD 3.4) postflight (P = 0.033); preflight with thigh cuffs inflated, low-frequency gain was 9.4 (SD 4.3) ms/mmHg. There was a shift in time-domain-determined pulse interval-to-pressure lag, Tau, toward higher values (P < 0.001). None of the postflight results were mimicked during preflight venous occlusion. In conclusion, two of five cosmonauts showed abnormal orthostatic response 1 and 2 days after spaceflight. Overall, there were indications of increased sympathetic response to standing, even though we can expect (partial) restoration of plasma volume to have taken place. Preflight venous occlusion did not mimic the postflight orthostatic response.

Human cerebral venous outflow pathway depends on posture and central venous pressure.

Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position, but mainly through the vertebral plexus in the upright position. A Valsalva manoeuvre while standing completely re-opened the jugular veins. Results of ultrasound imaging of the right internal jugular vein cross-sectional area at the level of the laryngeal prominence in six healthy subjects, before and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R(2) = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway. The internal jugular veins are collapsed in the standing position and blood is shunted to an alternative venous pathway, but a marked increase in CVP while standing completely re-opens the jugular veins.

Dynamic cerebral autoregulation under sinusoidal gravitational loading.

Dynamic cerebral autoregulation (CA) has been studied previously using spectral analysis of oscillations in arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). The dynamics of the CA can be modeled as a high-pass filter. The purpose of this study is to compare CA of blood pressure oscillations induced by gravitational loading to CA during resting conditions. We subjected twelve healthy subjects to repeated sinusoidal head-up (0 degrees - 60 degrees) tilts at several set frequencies (0.07 to 0.25 Hz) on a computer controlled tilt table while we recorded ABP (Finapres) and CBFV (transcranial Doppler ultrasound). We fitted the data sets to a high-pass filter model and computed an average time constant (T). Our results show similar phase leads of CBFV to ABPbrain in the rest recording and in sinusoidal tilting, in the studied frequency range. The transfer function gain of the resting spectra increased with increasing frequency, the gain of the tilting spectra did not. Fitting the phase responses of both data sets to a high pass filter model yielded similar time constants.