Jazuli F, Pyke KE. The impact of baseline artery diameter on flow-mediated vasodilation: a comparison of brachial and radial artery responses to matched levels of shear stress. Am J Physiol Heart Circ Physiol 301: H1667-H1677, 2011. First published July 22, 2011; doi:10.1152/ajpheart.00487.2011.-An inverse relationship between baseline artery diameter (BAD) and flow-mediated vasodilation (FMD) has been identified using reactive hyperemia (RH) to create a shear stress (SS) stimulus in human conduit arteries. However, RH creates a SS stimulus that is inversely related to BAD. The purpose of this study was to compare FMD in response to matched levels of SS in two differently sized upper limb arteries [brachial (BA) and radial (RA) artery]. With the use of exercise, three distinct, shear rate (SR) stimuli were created (SR ϭ blood velocity/vessel diameter; estimate of SS) in the RA and BA. Artery diameter and mean blood velocity were assessed with echo and Doppler ultrasound in 15 healthy male subjects (19 -25 yr). Data are means Ϯ SE. Subjects performed 6 min of adductor pollicis and handgrip exercise to increase SR in the RA and BA, respectively. Exercise intensity was modulated to achieve uniformity in SR between arteries. The three distinct SR levels were as follows: steady-state exercise 39.8 Ϯ 0.6, 57.3 Ϯ 0.7, and 72.4 Ϯ 1.2 s Ϫ1 (P Ͻ 0.001). %FMD and AbsFMD (mm) at the end of exercise were greater in the RA vs. the BA at each shear level [at the highest level: RA ϭ 15.7 Ϯ 1.5%, BA ϭ 5.4 Ϯ 0.8% (P Ͻ 0.001)]. The mean slope of the within-subject SR-%FMD regression line was greater in the RA (RA ϭ 0.33 Ϯ 0.04, BA ϭ 0.13 Ϯ 0.02, P Ͻ 0.001), and a strong within-subjects relationship between %FMD and SR was observed in both arteries (RA: r 2 ϭ 0.92 Ϯ 0.02; BA: r 2 ϭ 0.90 Ϯ 0.03). Within the RA, there was a significant relationship between baseline diameter and %FMD; however, this relationship was not present in the BA (RA: r 2 ϭ 0.76, P Ͻ 0.001; BA: r 2 ϭ 0.03, P ϭ 0.541). These findings suggest that the response to SS is not uniform across differently sized vessels, which is in agreement with previous studies. endothelial function; doppler ultrasound; shear stress; handgrip exercise; baseline diameter THE ENDOTHELIAL CELLS THAT line the arteries are critically involved in the maintenance of vascular homeostasis. In healthy arteries, increases in blood flow-associated shear stress lead to the release of vasodilators [e.g., nitric oxide (NO), endothelial-derived hyperpolarizing factor (EDHF), and prostacyclin] by the endothelium, resulting in an endotheliumdependent vasodilation [flow-mediated vasodilation (FMD)] (1, 3, 28, 35). An inverse relationship between baseline vessel diameter and the magnitude of the conduit artery FMD response in the arm has been reported by several studies (19,42,49,52). As a result, it can be difficult to use FMD to compare endothelial function in groups with varying baseline artery sizes (for example, the young vs. the elderly and men vs. women) because it may be unclear whether a small...

Reactive hyperemia (RH) creates an uncontrolled, transient increase in brachial artery (BA) shear stress (SS) for flow-mediated dilation (FMD) assessment. In contrast, handgrip exercise (HGEX) can create similar, sustained SS increases over repeated trials. The purpose of this study was to examine the impact of repeated SS elevation via RH or HGEX and the relationship between RH and HGEX %FMD. BA diameter and blood velocity were assessed with echo and Doppler ultrasound in 20 healthy subjects. Visit A consisted of four 6-min HGEX trials (HGEX trials 1-4) at the intensity required to achieve a shear rate (SR = mean blood velocity/BA diameter; an estimate of SS) of 65 s(-1). Visit B consisted of four RH trials (RH trials 1-4). The RH SR area under the curve (AUC) was higher in trial 1 versus trial 3 and trial 4 (P = 0.019 and 0.047). The HGEX mean SR was similar across trials (mean SR = 66.1 ± 5.8 s(-1), P = 0.152). There were no differences in %FMD across trials or tests (RH trial 1: 6.9 ± 3.5%, trial 2: 6.9 ± 2.3%, trial 3: 7.1 ± 3.5%, and trial 4: 7.0 ± 2.8%; HGEX trial 1: 7.3 ± 3.6%, trial 2: 7.0 ± 3.6%, trial 3: 6.5 ± 3.5%, and trial 4: 6.8 ± 2.9%, P = 0.913). No relationship between subject's RH %FMD and HGEX %FMD was detected (r(2) = 0.12, P = 0.137). However, with response normalization, a relationship emerged (RH %FMD/SR AUC vs. HGEX %FMD/mean SR, r(2) = 0.44, P = 0.002). In conclusion, with repeat trials, there were no systematic changes in RH or HGEX %FMD. The relationship between normalized RH and HGEX %FMD suggests that endothelial responses to different SS profiles provide related information regarding endothelial function.

The coronavirus disease 2019 (COVID-19) pandemic introduced challenges to the use of simulation, including limited personal protective equipment and restricted time and personnel. Our use of video for in situ simulation aimed to circumvent these challenges and assist in the development of a protocol for protected intubation and simultaneously educate emergency department (ED) staff. We video-recorded a COVID-19 respiratory failure in situ simulation event, which was shared by a facilitator both virtually and in the ED. The facilitator led discussions and debriefs. We followed this with in situ runthroughs in which staff walked through the steps of the simulation in the ED, handling medications and equipment and becoming comfortable with use of isolation rooms. This application of in situ simulation allowed one simulation event to reach a wide audience, while allowing participants to respect social distancing, and resulted in the education of this audience and successful crowdsourcing for a protocol amidst a pandemic.

Given the high risk of healthcare worker (HCW) infection with COVID-19 during aerosol-generating medical procedures, the use of a box barrier during intubation for protection of HCWs has been examined. Previous simulation work has demonstrated its efficacy in protecting HCWs from cough-expelled droplets. Our objective was to assess its ability to protect HCWs against aerosols generated during aerosol-generating medical procedures. We used a battery-powered vapouriser to assess movement of vapour with: (1) no barrier; (2) a box barrier; and (3) a box barrier and a plastic sheet covering the box and patient’s body. We visualised the trajectory of vapour and saw that the vapour remained within the barrier space when the box barrier and plastic sheet were used. This is in contrast to the box barrier alone, where vapour diffused towards the feet of the patient and throughout the room, and to no barrier where the vapour immediately diffused to the laryngoscopist. This demonstrates that the box with the plastic sheet has the potential to limit the spread of aerosols towards the laryngoscopist, and thus may play a role in protecting HCWs during aerosol-generating medical procedures. This is of particular importance in the care of patients with suspected COVID-19.

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Purpose of Review Point-of-care dengue diagnostics are unavailable in most settings; thus, diagnosis is clinical until more definitive microbiological testing -such as serology -is resulted. Thrombocytopenia and lymphopenia are common hallmarks of dengue fever; however, neutropenia is a prominent, yet less frequently reported trend. We aimed to identify hematological patterns that can assist frontline clinicians with diagnostic certainty of dengue. Dengue patients presenting to our unit via the Emergency Department were compared to those presenting with other febrile illness (OFI) diagnoses. Patient demographics, day of illness, and neutrophil, lymphocyte, and platelet counts from days 1 to 14 of illness were collected, where available. Analyses were stratified by day of illness. Recent Findings Eighteen patients were included in the dengue group and 151 in the OFI group. The frequency of thrombocytopenia, neutropenia, and lymphopenia was each significantly greater in the dengue cohort than in the OFI group (p < 0.0001). Mean nadir platelet, neutrophil, and lymphocyte counts were significantly lower in the dengue cohort compared to those with OFI (p < 0.001), and the likelihood of a dengue patient having the constellation of thrombocytopenia, neutropenia, and lymphopenia on a single CBC during acute illness was 30-fold higher than in the OFI group (p < 0.0001). Summary As dengue-specific diagnostic testing is often limited by insensitive early serologic diagnostics with prolonged turnaround time, the constellation of thrombocytopenia, neutropenia, and lymphopenia can guide the early diagnostic and treatment approach as well as follow-up of febrile returned travelers with suspected dengue.

BackgroundFever in the returned traveller is a potential medical emergency warranting prompt attention to exclude life-threatening illnesses. However, prolonged evaluation in the emergency department (ED) may not be required for all patients. As a quality improvement initiative, we implemented an algorithm for rapid assessment of febrile travelers (RAFT) in an ambulatory setting.MethodsCriteria for RAFT referral include: presentation to the ED, reported fever and travel to the tropics or subtropics within the past year. Exclusion criteria include Plasmodium falciparum malaria, and fulfilment of admission criteria such as unstable vital signs or significant laboratory derangements. We performed a time series analysis preimplementation and postimplementation, with primary outcome of wait time to tropical medicine consultation. Secondary outcomes included number of ED visits averted for repeat malaria testing, and algorithm adherence.ResultsFrom February 2014 to December 2015, 154 patients were seen in the RAFT clinic: 68 men and 86 women. Median age was 36 years (range 16–78 years). Mean time to RAFT clinic assessment was 1.2±0.07 days (range 0–4 days) postimplementation, compared to 5.4±1.8 days (range 0–26 days) prior to implementation (p<0.0001). The RAFT clinic averted 132 repeat malaria screens in the ED over the study period (average 6 per month). Common diagnoses were: traveller's diarrhoea (n=27, 17.5%), dengue (n=12, 8%), viral upper respiratory tract infection (n=11, 7%), chikungunya (n=10, 6.5%), laboratory-confirmed influenza (n=8, 5%) and lobar pneumonia (n=8, 5%).ConclusionsIn addition to provision of more timely care to ambulatory febrile returned travellers, we reduced ED bed-usage by providing an alternate setting for follow-up malaria screening, and treatment of infectious diseases manageable in an outpatient setting, but requiring specific therapy.

PURPOSETo understand how O2del: metabolism matching is defended in the face of increased duration of contraction‐induced mechanical impedance to exercising muscle blood flow.METHODS7 healthy young males, (21.8 ±1.8 yrs) performed a handgrip ramp exercise protocol (increase contraction force 2.5 kg every 3 min) under Control (CON; 2 s isometric contraction + forearm compression cuff inflation: 4 s relaxation duty cycle) and Impedance (IMP; 2 s contraction + forearm compression + extra 2 s of forearm compression: 2 s relaxation duty cycle). Forearm blood flow ((FBF (ml/min); brachial artery Doppler and Echo ultrasound), mean arterial blood pressure (MAP (mmHg); finger photoplethysmography) were measured. Forearm vascular conductance during relaxation (FVCrelax ml/min/100 mmHg)) was calculated (FBFrelax/MAP x 100).RESULTSData are mean ± SD. Up to 7.5 kg workload, FBF (therefore O2del) was not different between conditions due to compensatory vasodilation in IMP (eg. 7.5 kg FVCrelax IMP 596 ±140 vs. CON 396 ±60, P<0.05). Above 7.5 kg workload a small pressor response in IMP was added (MAP IMP 103.5 ±7.8 vs. CON 98.8 ±8.6, P<0.05), but O2del: metabolism matching was not achieved.CONCLUSIONSCompensatory vasodilation successfully maintains O2del: metabolism matching at lower workloads. When it fails, a pressor response is evoked, but cannot maintain O2del: metabolism matching at higher workloads. NSERC.