Association Between Frailty and Head Impact Location After Ground-Level Fall in Older Adults

BACKGROUND

Mild traumatic brain injuries (TBIs) are highly prevalent in older adults, and ground-level falls are the most frequent mechanism of injury.

OBJECTIVE

This study aimed to assess whether frailty was associated with head impact location among older patients who sustained a ground-level fall-related, mild TBI. The secondary objective was to measure the association between frailty and intracranial hemorrhages.

METHODS

We conducted a planned sub-analysis of a prospective observational study in two urban university-affiliated emergency departments (EDs). Patients 65 years and older who sustained a ground-level fall-related, mild TBI were included if they consulted in the ED between January 2019 and June 2019. Frailty was assessed using the Clinical Frailty Scale (CFS). Patients were stratified into the following three groups: robust (CFS score 1-3), vulnerable-frail (CFS score 4-6), and severely frail (CFS score 7-9).

RESULTS

A total of 335 patients were included; mean ± SD age was 86.9 ± 8.1 years. In multivariable analysis, frontal impact was significantly increased in severely frail patients compared with robust patients (odds ratio [OR] 4.8 [95% CI 1.4-16.8]; p = 0.01). Intracranial hemorrhages were found in 6.2%, 7.5%, and 13.3% of robust, vulnerable-frail, and severely frail patients, respectively. The OR of intracranial hemorrhages was 1.24 (95% CI 0.44-3.45; p = 0.68) in vulnerable-frail patients and 2.34 (95% CI 0.41-13.6; p = 0.34) in those considered severely frail.

CONCLUSIONS

This study found an association between the level of frailty and the head impact location in older patients who sustained a ground-level fall. Our results suggest that head impact location after a fall can help physicians identify frail patients. Although not statistically significant, the prevalence of intracranial hemorrhage seems to increase with the level of frailty.

Lack of association between four biomarkers and persistent post-concussion symptoms after a mild traumatic brain injury

Approximately 15 % of individuals who sustained a mild Traumatic Brain Injury (TBI) develop persistent post-concussion symptoms (PPCS). We hypothesized that blood biomarkers drawn in the Emergency Department (ED) could help predict PPCS. The main objective of this project was to measure the association between four biomarkers and PPCS at 90 days post mild TBI. We conducted a prospective cohort study in seven Canadian EDs. Patients aged ≥ 14 years presenting to the ED within 24 h of a mild TBI who were discharged were eligible. Clinical data and blood samples were collected in the ED, and a standardized questionnaire was administered 90 days later to assess the presence of symptoms. The following biomarkers were analyzed: S100B protein, Neuron Specific Enolase (NSE), cleaved-Tau (c-Tau) and Glial Fibrillary Acidic Protein (GFAP). The primary outcome measure was the presence of PPCS at 90 days after trauma. Relative risks and Areas Under the Curve (AUC) were computed. A total of 595 patients were included, and 13.8 % suffered from PPCS at 90 days. The relative risk of PPCS was 0.9 (95 % CI: 0.5-1.8) for S100B ≥ 20 pg/mL, 1.0 (95 % CI: 0.6-1.5) for NSE ≥ 200 pg/mL, 3.4 (95 % CI: 0.5-23.4) for GFAP ≥ 100 pg/mL, and 1.0 (95 % CI: 0.6-1.8) for C-Tau ≥ 1500 pg/mL. AUC were 0.50, 0.50, 0.51 and 0.54, respectively. Among mild TBI patients, S100B protein, NSE, c-Tau or GFAP do not seem to predict PPCS. Future research testing of other biomarkers is needed to determine their usefulness in predicting PPCS.

Relationship between systolic blood pressure and mortality in older vs younger trauma patients - a retrospective multicentre observational study

BACKGROUND

The population of older trauma patients is increasing. Those patients have heterogeneous presentations and need senior-friendly triaging tools. Systolic blood pressure (SBP) is commonly used to assess injury severity, and some authors advocated adjusting SBP threshold for older patients. We aimed to describe and compare the relationship between mortality and SBP in older trauma patients and their younger counterparts.

METHODS

We included patients admitted to three level-I trauma centres and performed logistic regressions with age and SBP to obtain mortality curves. Multivariable Logistic regressions were performed to measure the association between age and mortality at different SBP ranges. Subgroup analyses were conducted for major trauma and severe traumatic brain injury admissions.

RESULTS

A total of 47,661 patients were included, among which 12.9% were aged 65-74 years and 27.3% were ≥ 75 years. Overall mortality rates were 3.9%, 8.1%, and 11.7% in the groups aged 16-64, 65-74, and ≥ 75 years, respectively. The relationship between prehospital SBP and mortality was nonlinear (U-shape), mortality increased with each 10 mmHg SBP decrement from 130 to 50 mmHg and each 10-mmHg increment from 150 to 220 mmHg across all age groups. Older patients were at higher odd for mortality in all ranges of SBP. The highest OR in patients aged 65-74 years was 3.67 [95% CI: 2.08-6.45] in the 90-99 mmHg SBP range and 7.92 [95% CI: 5.13-12.23] for those aged ≥ 75 years in the 100-109 mmHg SBP range.

CONCLUSION

The relationship between SBP and mortality is nonlinear, regardless of trauma severity and age. Older age was associated with a higher odd of mortality at all SBP points. Future triage tools should therefore consider SBP as a continuous rather than a dichotomized predictor.

Risk factors and mortality associated with undertriage after major trauma in a physician-led prehospital system: a retrospective multicentre cohort study

PURPOSE

To assess the incidence of undertriage in major trauma, its determinant, and association with mortality.

METHODS

A multicentre retrospective cohort study was conducted using data from a French regional trauma registry (2011-2017). All major trauma (Injury Severity Score ≥ 16) cases aged ≥ 18 years and managed by a physician-led mobile medical team were included. Those transported to a level-II/III trauma centre were considered as undertriaged. Multivariable logistic regression was used to identify factors associated with undertriage.

RESULTS

A total of 7110 trauma patients were screened; 2591 had an ISS ≥ 16 and 320 (12.4%) of these were undertriaged. Older patients had higher risk for undertriage (51-65 years: OR = 1.60, 95% CI [1.11; 2.26], p = 0.01). Conversely, injury mechanism (fall from height: 0.62 [0.45; 0.86], p = 0.01; gunshot/stab injuries: 0.45 [0.22; 0.90], p = 0.02), on-scene time (> 60 min: 0.62 [0.40; 0.95], p = 0.03), prehospital endotracheal intubation (0.53 [0.39; 0.71], p < 0.001), and prehospital focussed assessment with sonography [FAST] (0.15 [0.08; 0.29], p < 0.001) were associated with a lower risk for undertriage. After adjusting for severity, undertriage was not associated with a higher risk of mortality (1.22 [0.80; 1.89], p = 0.36).

CONCLUSIONS

In our physician-led prehospital EMS system, undertriage was higher than recommended. Advanced aged was identified as a risk factor highlighting the urgent need for tailored triage protocol in this population. Conversely, the potential benefit of prehospital FAST on triage performance should be furthered explored as it may reduce undertriage. Fall from height and penetrating trauma were associated with a lower risk for undertriage suggesting that healthcare providers should remain vigilant of the potential seriousness of trauma associated with low-energy mechanisms.

Effect of age on the association between the Glasgow Coma Scale and the anatomical brain lesion severity: a retrospective multicentre study

Background and importance Older adults are at higher risk of undertriage and mortality following a traumatic brain injury (TBI). Early identification and accurate triage of severe cases is therefore critical. However, the Glasgow Coma Scale (GCS) might lack sensitivity in older patients. Objective This study investigated the effect of age on the association between the GCS and TBI severity. Design, settings, and participants This multicentre retrospective cohort study (2003-2017) included TBI patients aged ≥16 years with an Abbreviated Injury Scale (AIS of 3, 4 or 5). Older adults were defined as aged 65 and over. Outcomes measure and analysis Median GCS score were compared between older and younger adults, within subgroups of similar AIS. Multivariable logistic regressions were computed to assess the association between age and mortality. The primary analysis comprised patients with isolated TBI, and secondary analysis included patients with multiple trauma. Main results A total of 12 562 patients were included, of which 9485 (76%) were isolated TBIs. Among those, older adults represented 52% ( n  = 4931). There were 22, 27 and 51% of older patients with an AIS-head of 3, 4 and 5 respectively compared to 32, 25 and 43% among younger adults. Within the different subgroups of patients, median GCS scores were higher in older adults: 15 (14-15) vs. 15 (13-15), 15 (14-15) vs. 14 (13-15), 15 (14-15) vs. 14 (8-15), for AIS-head 3, 4 and 5 respectively (all P  < 0.0001). Older adults had increased odds of mortality compared to their younger counterparts at all AIS-head levels: AIS-head = 3 [odds ratio (OR) = 2.9, 95% confidence interval (CI) 1.6-5.5], AIS-head = 4, (OR = 2.7, 95% CI 1.6-4.7) and AIS-head = 5 (OR = 2.6, 95% CI 1.9-3.6) TBI (all P  < 0.001). Similar results were found among patients with multiple trauma. Conclusions In this study, among TBI patients with similar AIS-head score, there was a significant higher median GCS in older patients compared to younger patients.

Epidemiology, injury pattern and outcome of older trauma patients: A 15-year study of level-I trauma centers

BACKGROUND

Older adults have become a significant portion of the trauma population. Exploring their specificities is crucial to better meet their specific needs. The primary objective was to evaluate the temporal changes in the incidence, demographic and trauma characteristics, injury pattern, in-hospital admission, complications, and outcome of older trauma patients.

METHODS

A multicenter retrospective cohort study was conducted using the Quebec Trauma Registry. Patients aged ≥16 years admitted to one of the three adult level-I trauma centers between 2003 and 2017 were included. Descriptive analyses and trend-tests were performed to describe temporal changes.

RESULTS

A total of 53,324 patients were included, and 24,822 were aged ≥65 years. The median [IQR] age increased from 57[36-77] to 67[46-82] years, and the proportion of older adults rose from 41.8% in 2003 to 54.1% in 2017. Among those, falls remain the main mechanism (84.7%-88.3%), and the proportion of severe thorax (+8.9%), head (+8.7%), and spine (+5%) injuries significantly increased over time. The proportion of severely injured older patients almost doubled (17.6%-32.3%), yet their mortality decreased (-1.0%). Their average annual bed-days consumption also increased (+15,004 and +1,437 in non-intensive care wards and ICU, respectively).

CONCLUSIONS

Since 2014, older adults have represented the majority of admissions in Level-I trauma centers in Québec. Their bed-days consumption has greatly increased, and their injury pattern and severity have deeply evolved, while we showed a decrease in mortality.

Post-Concussion Symptoms Rule: Derivation and Validation of a Clinical Decision Rule for Early Prediction of Persistent Symptoms after a Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is a common problem. Depending on diagnostic criteria, 13 to 62% of those patients develop persistent post-concussion symptoms (PPCS). The main objective of this prospective multi-center study is to derive and validate a clinical decision rule (CDR) for the early prediction of PPCS. Patients aged ≥14 years were included if they presented to one of our seven participating emergency departments (EDs) within 24 h of an mTBI. Clinical data were collected in the ED, and symptom evolution was assessed at 7, 30 and 90 days post-injury using the Rivermead Post-Concussion Questionnaire (RPQ). The primary outcome was PPCS at 90 days after mTBI. A predictive model called the Post-Concussion Symptoms Rule (PoCS Rule) was developed using the methodological standards for CDR. Of the 1083 analyzed patients (471 and 612 for the derivation and validation cohorts, respectively), 15.6% had PPCS. The final model included the following factors assessed in the ED: age, sex, history of prior TBI or mental health disorder, headache in ED, cervical sprain and hemorrhage on computed tomography. The 7-day follow-up identified additional risk factors: headaches, sleep disturbance, fatigue, sensitivity to light, and RPQ ≥21. The PoCS Rule had a sensitivity of 91.4% and 89.6%, a specificity of 53.8% and 44.7% and a negative predictive value of 97.2% and 95.8% in the derivation and validation cohorts, respectively. The PoCS Rule will help emergency physicians quickly stratify the risk of PPCS in mTBI patients and better plan post-discharge resources.

Survey on Current Practice of Canadian Physicians Regarding the Investigation in Older Patients with Delirium

Background

The current literature provides heterogeneous recommendation regarding the investigation of older delirious patients, which may lead to over-testing. Our study aims to describe Canadian physicians’ current practice for the investigation of older patients with delirium. Our secondary objective is to define specific indications for performing a CT head scan in this population.

Methods

Design: cross-sectional online survey. Participants: physicians who conduct their clinical practice in Canada and who care for older patients with delirium. Potential study participants were reached through Canadian associations: Canadian Geriatrics Society, the Canadian Association of Emergency Physicians, the Association des Médecins d’Urgence du Québec, and members of Choosing Wisely Canada.

Results

We received 296 survey responses. More than 80% of respondents always order complete blood count, urea, and creatinine and electrolytes. Extended electrolytes, TSH, chest X-ray, electrocardiogram, urinalysis and urinary culture tests tend to be ordered somewhat frequently. Physicians mostly agreed to order a head CT scan for loss of consciousness, altered mental status, fall, and anticoagulation.

Conclusions

Physicians’ investigations for older patients with delirium are highly variable, even with the lack of evidence supporting a broad workup. Also, respondents mostly align with current recommendations of indications for CT head scans.

Is in situ simulation in emergency medicine safe? A scoping review

OBJECTIVES

To provide an overview of the available evidence regarding the safety of in situ simulation (ISS) in the emergency department (ED).

DESIGN

Scoping review.

METHODS

Original articles published before March 2021 were included if they investigated the use of ISS in the field of emergency medicine.

INFORMATION SOURCES

MEDLINE, EMBASE, Cochrane and Web of Science.

RESULTS

A total of 4077 records were identified by our search strategy and 2476 abstracts were screened. One hundred and thirty full articles were reviewed and 81 full articles were included. Only 33 studies (40%) assessed safety-related issues, among which 11 chose a safety-related primary outcome. Latent safety threats (LSTs) assessment was conducted in 24 studies (30%) and the cancellation rate was described in 9 studies (11%). The possible negative impact of ISS on real ED patients was assessed in two studies (2.5%), through a questionnaire and not through patient outcomes.

CONCLUSION

Most studies use ISS for systems-based or education-based applications. Patient safety during ISS is often evaluated in the context of identifying or mitigating LSTs and rarely on the potential impact and risks to patients simultaneously receiving care in the ED. Our scoping review identified knowledge gaps related to the safe conduct of ISS in the ED, which may warrant further investigation.

Road traffic accident-related thoracic trauma: Epidemiology, injury pattern, outcome, and impact on mortality—A multicenter observational study

Background

Thoracic trauma is a major cause of death in trauma patients and road traffic accident (RTA)-related thoracic injuries have different characteristics than those with non-RTA related thoracic traumas, but this have been poorly described. The main objective was to investigate the epidemiology, injury pattern and outcome of patients suffering a significant RTA-related thoracic injury. Secondary objective was to investigate the influence of serious thoracic injuries on mortality, compared to other serious injuries.

Methods

We performed a multicenter observational study including patients of the Rhône RTA registry between 1997 and 2016 sustaining a moderate to lethal (Abbreviated Injury Scale, AIS≥2) injury in any body region. A subgroup (AISThorax≥2 group) included those with one or more AIS≥2 thoracic injury. Descriptive statistics were performed for the main outcome and a multivariate logistic regression was computed for our secondary outcome.

Results

A total of 176,346 patients were included in the registry and 6,382 (3.6%) sustained a thoracic injury. Among those, median age [IQR] was 41 [25–58] years, and 68.9% were male. The highest incidence of thoracic injuries in female patients was in the 70–79 years age group, while this was observed in the 20–29 years age group among males. Most patients were car occupants (52.3%). Chest wall injuries were the most frequent thoracic injuries (62.1%), 52.4% of which were multiple rib fractures. Trauma brain injuries (TBI) were the most frequent concomitant injuries (29.1%). The frequency of MAISThorax = 2 injuries increased with age while that of MAISThorax = 3 injuries decreased. A total of 16.2% patients died. Serious (AIS≥3) thoracic injuries (OR = 12.4, 95%CI [8.6;18.0]) were strongly associated with mortality but less than were TBI (OR = 27.9, 95%CI [21.3;36.7]).

Conclusion

Moderate to lethal RTA-related thoracic injuries were rare. Multiple ribs fractures, pulmonary contusions, and sternal fractures were the most frequent anatomical injuries. The incidence, injury pattern and mechanisms greatly vary across age groups.

Prevalence, management and outcomes of unrecognized delirium in a National Sample of 1,493 older emergency department patients: how many were sent home and what happened to them?

BACKGROUND

Retrospective studies estimate Emergency Department (ED) delirium recognition at <20%; few prospective studies have assessed delirium recognition and outcomes for patients with unrecognized delirium.

OBJECTIVES

To prospectively measure delirium recognition by ED nurses and physicians, document their confidence in diagnosis and disposition, actual dispositions, and patient outcomes.

METHODS

Prospective observational study of people ≥65 years. We assessed delirium using the Confusion Assessment Method, then asked ED staff if the patient had delirium, confidence in their assessment, if the patient could be discharged, and contacted patients 1 week postdischarge. We report proportions and 95% confidence intervals (Cls).

RESULTS

We enrolled 1,493 participants; mean age was 77.9 years; 49.2% were female, 79 (5.3%, 95% CI 4.2-6.5%) had delirium. ED nurses missed delirium in 43/78 cases (55.1%, 95% CI 43.4-66.4%). Nurses considered 12/43 (27.9%) patients with unrecognized delirium safe to discharge. Median confidence in their delirium diagnosis for patients with unrecognized delirium was 7.0/10. Physicians missed delirium in 10/20 (50.0%, 95% CI 27.2-72.8) cases and considered 2/10 (20.0%) safe to discharge. Median confidence in their delirium diagnosis for patients with unrecognized delirium was 8.0/10. Fifteen patients with unrecognized delirium were sent home: 6.7% died at 1 week follow-up vs. none in those with recognized delirium and 1.1% in the rest of the cohort.

CONCLUSION

Delirium recognition by nurses and physicians was sub-optimal at ~50% and may be associated with increased mortality. Research should explore root causes of unrecognized delirium, and novel strategies to systematically improve delirium recognition and patient outcomes.

External validation of the updated Brain Injury Guidelines for complicated mild traumatic brain injuries: a retrospective cohort study

OBJECTIVE

Approximately 10% of patients with mild traumatic brain injury (mTBI) have intracranial bleeding (complicated mTBI) and 3.5% eventually require neurosurgical intervention, which is mostly available at centers with a higher level of trauma care designation and often requires interhospital transfer. In 2018, the Brain Injury Guidelines (BIG) were updated in the United States to guide emergency department care and patient disposition for complicated mild to moderate TBI. The aim of this study was to validate the sensitivity and specificity of the updated BIG (uBIG) for predicting the need for interhospital transfer in Canadian patients with complicated mTBI.

METHODS

This study took place at three level I trauma centers. Consecutive medical records of patients with complicated mTBI (Glasgow Coma Scale score 13-15) who were aged ≥ 16 years and presented between September 2016 and December 2017 were retrospectively reviewed. Patients with a penetrating trauma and those who had a documented cerebral tumor or aneurysm were excluded. The primary outcome was a combination of neurosurgical intervention and/or mTBI-related death. Sensitivity and specificity analyses were performed.

RESULTS

A total of 477 patients were included, of whom 8.4% received neurosurgical intervention and 3% died as a result of their mTBI. Forty patients (8%) were classified as uBIG-1, 168 (35%) as uBIG-2, and 269 (56%) as uBIG-3. No patients in uBIG-1 underwent neurosurgical intervention or died as a result of their injury. This translates into a sensitivity for predicting the need for a transfer of 100% (95% CI 93.2%-100%) and a specificity of 9.4% (95% CI 6.8%-12.6%). Using the uBIG could potentially reduce the number of transfers by 6% to 25%.

CONCLUSIONS

The patients in uBIG-1 could be safely managed at their initial center without the need for transfer to a center with a higher level of neurotrauma care. Although the uBIG could decrease the number of transfers, further refinement of the criteria could improve its specificity.

Investigation and treatment of asymptomatic bacteriuria in older patients with delirium: a cross-sectional survey of Canadian physicians

OBJECTIVES

Current guidelines suggest assessing non-infectious causes and careful observation before giving antibiotics to delirious patients with asymptomatic bacteriuria. Our study aims to describe the current practice of Canadian physicians regarding the investigation and treatment of asymptomatic bacteriuria in delirious older patients (aged ≥ 65 years).

METHODS

Our team of medical experts designed and reviewed a cross-sectional online survey. Study participants were physicians who conduct their clinical practice in Canada and care for older patients with delirium in their current practice. Potential study participants were reached through Canadian associations: Canadian Geriatrics Society, the Canadian Association of Emergency Physicians, the Association des Médecins d'Urgence du Québec and members of Choosing Wisely Canada.

RESULTS

297 physicians were included. The main results show 79.4% of our participants request a urine dipstick or urinalysis in delirious patients and 52.4% immediately order a urine culture with the urinalysis. If bacteriuria is found in delirious but afebrile patients without urinary symptoms, 38% of physicians immediately treat with antibiotics, 33.8% wait for culture before initiating treatment, 14.4% treat if no other cause is found for delirium and only 13.7% would refrain from giving antibiotics. Results from respondents were similar for delirious patients with known cognitive impairment. Participants were almost unanimous (92.5%) in saying they need clear guidelines regarding the treatment of bacteriuria in older delirious patients.

CONCLUSIONS

This survey highlights the heterogeneous clinical management of asymptomatic bacteriuria in delirious patients and the need for clear guidelines for patients.

Natural spring water gargle samples as an alternative to nasopharyngeal swabs for SARS-CoV-2 detection using a laboratory-developed test

The objective of this study was to validate the use of spring water gargle (SWG) as an alternative to oral and nasopharyngeal swab (ONPS) for SARS‐CoV‐2 detection with a laboratory‐developed test. Healthcare workers and adults from the general population, presenting to one of two COVID‐19 screening clinics in Montréal and Québec City, were prospectively recruited to provide a gargle sample in addition to the standard ONPS. The paired specimens were analyzed using thermal lysis followed by a laboratory‐developed nucleic acid amplification test (LD‐NAAT) to detect SARS‐CoV‐2, and comparative performance analysis was performed. An individual was considered infected if a positive result was obtained on either sample. A total of 1297 adult participants were recruited. Invalid results (n = 18) were excluded from the analysis. SARS‐CoV‐2 was detected in 144/1279 (11.3%) participants: 126 from both samples, 15 only from ONPS, and 3 only from SWG. Overall, the sensitivity was 97.9% (95% CI: 93.7–99.3) for ONPS and 89.6% (95% CI: 83.4–93.6; p = 0.005) for SWG. The mean ONPS cycle threshold (C_t) value was significantly lower for the concordant paired samples as compared to discordant ones (22.9 vs. 32.1; p < 0.001). In conclusion, using an LD‐NAAT with thermal lysis, SWG is a less sensitive sampling method than the ONPS. However, the higher acceptability of SWG might enable a higher rate of detection from a population‐based perspective. Nonetheless, in patients with a high clinical suspicion of COVID‐19, a repeated analysis with ONPS should be considered. The sensitivity of SWG using NAAT preceded by chemical extraction should be evaluated.

Using a laboratory‐developed NAAT preceded by thermal lysis, the overall percent agreement between spring water gargle (SWG) and oral combined with nasopharyngeal swab (ONPS), sampled at the same time among 1297 participants, is excellent (98.6%).

Although the SARS‐CoV‐2 NAAT from SWG is globally less sensitive than from ONPS (89.6% vs. 97.9%), the difference is markedly less in individuals symptomatic for <3 days (2.7%; p=NS) than in those whose symptoms started ≥7 days before testing (35.7%; p= 0.005).

Predictors of neurosurgical intervention in complicated mild traumatic brain injury patients: a retrospective cohort study

OBJECTIVES

To determine the predicting demographic, clinical and radiological factors for neurosurgical intervention in complicated mild traumatic brain injury (mTBI) patients.

METHODS

Design: retrospective multicenter cohort study. Participants: patients aged ≥16 presenting to all level-I trauma centers in Quebec between 09/2016 and 12/2017 with mTBI(GCS 13-15) and complication on initial head CT (intracranial hemorrhage/skull fracture). Procedure: Consecutive medical records were reviewed and separated into two groups: no neurosurgical intervention and neurosurgical intervention (NSI). Main outcome: neurosurgical intervention. Analysis: multiple logistic regression model.

RESULTS

Four hundred and seventy-eight patients were included and 40 underwent NSI. One patient had radiological deterioration but no clinical deterioration prior to surgery. Subdural hemorrhage ≥4 mm width (OR:3.755 [95% CI:1.290-10.928]) and midline shift (OR:7.507 [95% CI: 3.317-16.989]) increased the risk of NSI. Subarachnoid hemorrhage was associated with a lower risk of NSI (OR:0.312 [95% CI: 0.136-0.713]). All other intracranial hemorrhages were not associated with NSI.

CONCLUSION

Radiological deterioration was not associated with the incidence of NSI. Subdural hemorrhage and midline shift should be predicting factors for neurosurgery. Some patients with isolated findings such as subarachnoid hemorrhage could be safely managed in their original center without being transferred to a level-I trauma center.

Influence of concomitant injuries on post-concussion symptoms after a mild traumatic brain injury - a prospective multicentre cohort study

Objectives: To compare post-concussion symptoms (PCS) and return to normal activities between mild Traumatic Brain Injury (mTBI) patients with or without concomitant injuries at 7-and 90 days post-mTBI.Methods: Design: Sub-analysis of a multicentre prospective cohort study.

PARTICIPANTS AND SETTING

patients with mTBI from 7 Canadian Emergency Departments.

PROCEDURE

Research assistants conducted telephone follow-ups using the Rivermead Postconcussion Symptoms Questionnaire (RPQ) at 7-, 30- and 90 days post-mTBI.

MAIN OUTCOME

Presence of PCS (RPQ: ≥3 symptoms) at 90 days.

SECONDARY OUTCOMES

RPQ score ≥21, prevalence of individual RPQ symptoms and patients' return to normal activities, at 7- and 90-days. Adjusted risk ratios (RR) were calculated.Results: 1725 mTBI patients were included and 1055 (61.1%) had concomitant injuries. Patients with concomitant injuries were at higher risk of having ≥3 symptoms on the RPQ (RR:1.26 [95% CI 1.01-1.58]) at 90 days. They were also at higher risk of experiencing specific symptoms (dizziness, fatigue, headaches and taking longer to think) and of non-return to their normal activities (RR:2.11 [95% CI 1.30-3.45]).Conclusion: Patients with concomitant injuries have slightly more PCS and seemed to be at higher risk of non-return to their normal activities 90 days, compared to patients without concomitant injuries.

A Delphi study to identify prehospital and emergency department trauma care modifiers for older adults

Background

Older patients (age ≥ 65 yr) with trauma have increased morbidity and mortality compared to younger patients; this is partly explained by undertriage of older patients with trauma, resulting in lack of transfer to a trauma centre or failure to activate the trauma team. The objective of this study was to identify modifiers to the prehospital and emergency department phases of major trauma care for older adults based on expert consensus.

Methods

We conducted a modified Delphi study between May and September 2019 to identify major trauma care modifiers for older adults based on national expert consensus. The panel consisted of 24 trauma care professionals from across Canada from the prehospital and emergency department phases of care. The survey consisted of 16 trauma care modifiers. Three online survey rounds were distributed. Consensus was defined a priori as a disagreement index score less than 1.

Results

There was a 100% response rate for all survey rounds. Three new trauma care modifiers were suggested by panellists. The panel achieved consensus agreement for 17 of the 19 trauma care modifiers. The prehospital modifier with the strongest agreement to transfer to a trauma centre was a respiratory rate less than 10 or greater than 20 breaths/min or need for ventilatory support. The emergency department modifier with the strongest level of agreement was obtaining 12-lead electrocardiography following the primary and secondary survey.

Conclusion

Using a modified Delphi process, an expert panel agreed on 17 trauma care modifiers for older adults in the prehospital and emergency department settings. These modifiers may improve the delivery of trauma care for older adults and should be considered when developing local and national trauma guidelines.

Evaluation of the feasibility and impacts of in situ simulation in emergency medicine-a mixed-method study protocol

INTRODUCTION

In situ simulation (ISS) consists of performing a simulation in the everyday working environment with the usual team members. The feasibility of ISS in emergency medicine is an important research question, because ISS offers the possibility for repetitive, regular simulation training consistent with specific local needs. However, ISS also raises the issue of safety, since it might negatively impact the care of other patients in the emergency department (ED). Our hypothesis is that ISS in an academic high-volume ED is feasible, safe and associated with benefits for both staff and patients.

METHODS

A mixed-method, including a qualitative method for the assessment of feasibility and acceptability and a quantitative method for the assessment of patients' safety and participants' psychosocial risks, will be used in this study.Two distinct phases are planned in the ED of the CHU de Québec-Université Laval (Hôpital de l'Enfant-Jésus) between March 2021 and October 2021. Phase 1: an ISS programme will be implemented with selected ED professionals to assess its acceptability and safety and prove the validity of our educational concept. The number of cancelled sessions and the reasons for cancellation will be collected to establish feasibility criteria. Semistructured interviews will evaluate the acceptability of the intervention. We will compare unannounced and announced ISS. Phase 2: the impact of the ISS programme will be measured with validated questionnaires for the assessment of psychosocial risks, self-confidence and perceived stress among nonselected ED professionals, with comparison between those exposed to ISS and those that were not.

ETHICS AND DISSEMINATION

The CHU de Québec-Université Laval Research ethics board has approved this protocol (#2020-5000). Results will be presented to key professionals from our institution to improve patient safety. We also aim to publish our results in peer-reviewed journals and will submit abstracts to international conferences to disseminate our findings.

Self-assessment of functional status in older emergency department patients: a cross-over randomized pilot trial

OBJECTIVE

To assess the inter-rater reliability and feasibility of the self-assessed Older Americans Resources and Services scale compared to its administration by a research assistant in older Emergency Department (ED) patients.

METHOD

This is a planned sub-analysis of a single-center randomized cross-over pilot study. A convenience sample of ED patients aged ≥ 65 was constituted at the CHU de Québec-Université Laval (Hôpital de l'Enfant-Jésus) between 2018/05 and 2018/07. Research assistants assessed participants' functional status using the Older Americans Resources and Services scale and patients self-assessed using a modified Older Americans Resources and Services scale. Test administration order was randomized. The main outcome, inter-rater reliability, was measured using intraclass correlation (ICC). Feasibility was measured using self-assessment completion rate.

RESULTS

67 patients were included and 60 completed self-assessment. Mean age was 74.4 ± 7.6 and 34 (56.7%) participants were women. Mean research assistant-assessed Older Americans Resources and Services scale score was 25.1 ± 3.3, while mean self-assessed Older Americans Resources and Services scale score was 26.4 ± 2.5 [ICC: 0.8 (95% CI: 0.7-0.9)]. Mean activities of daily living scores were 12.5 ± 1.8 for research assistant assessment and 13.5 ± 0.9 for self-assessment [ICC: 0.6 (95% CI: 0.4-0.7)]. Mean instrumental activities of daily living scores were 12.6 ± 1.8 and 12.9 ± 1.8 for research assistant assessment and self-assessment, respectively [ICC: 0.9 (95% CI: 0.8-0.9)].

CONCLUSION

Our results indicate that self-assessment of functional status by older ED patients is feasible, and good-to-moderate inter-rater reliability results were obtained. A self-assessed score may identify patients in need of further geriatric/functional assessment who may otherwise have been left unscreened.

Functional and cognitive decline in older delirious adults after an emergency department visit

BACKGROUND

the aim of this study was to evaluate the impact of emergency department (ED) stay-associated delirium on older patient's functional and cognitive status at 60 days post ED visit.

METHODS

this study was part of the multi-centre prospective cohort INDEED study. This project took place between March 2015 and July 2016 in five participating EDs across the province of Quebec. Independent non-delirious patients aged ≥65, with an ED stay ≥8 hours, were monitored for delirium until 24 hours post ward admission. A 60-day follow-up phone assessment was conducted. Participants were screened for delirium using the Confusion Assessment Method. Functional and cognitive statuses were assessed at baseline and at the 60-day follow-up using OARS and TICS-m.

RESULTS

a total of 608 patients were recruited, 393 of which completed the 60-day follow-up. The Confusion Assessment Method was positive in 69 patients (11.8%) during ED stay or within the first 24 hours following ward admission. At 60 days, delirium patients experienced an adjusted loss of -2.9/28 [95%CI: -3.9, -2.0] points on the OARS scale compared to non-delirious patients who lost -1.6 [95%CI: -1.9, -1.3] (P = 0.006). A significant adjusted difference in cognitive function was also noted at 60 days, as TICS-m scores in delirious patients decreased by -1.6 [95%CI: -3.5, 0.2] compared to non-delirious patients, who showed a minor improvement of 0.5 [95%CI: -0.1, 1.1] (P = 0.03).

CONCLUSION

seniors who developed ED stay-associated delirium have lower baseline functional and cognitive status than non-delirious patients, and they will experience a more significant decline at 60 days post ED visit.

S100B protein level for the detection of clinically significant intracranial haemorrhage in patients with mild traumatic brain injury: a subanalysis of a prospective cohort study

Background

Clinical assessment of patients with mild traumatic brain injury (mTBI) is challenging and overuse of head CT in the ED is a major problem. Several studies have attempted to reduce unnecessary head CTs following a mTBI by identifying new tools aiming to predict intracranial bleeding. Higher levels of S100B protein have been associated with intracranial haemorrhage following a mTBI in previous literature. The main objective of this study is to assess whether plasma S100B protein level is associated with clinically significant brain injury and could be used to reduce the number of head CT post-mTBI.

Methods

Study design: secondary analysis of a prospective multicentre cohort study conducted between 2013 and 2016 in five Canadian EDs. Inclusion criteria: non-hospitalised patients with mTBI with a GCS score of 13–15 in the ED and a blood sample drawn within 24 hours after the injury. Data collected: sociodemographic and clinical data were collected in the ED. S100B protein was analysed using ELISA. All CT scans were reviewed by a radiologist blinded to the biomarker results. Main outcome: the presence of clinically important brain injury.

Results

476 patients were included. Mean age was 41±18 years old and 150 (31.5%) were women. Twenty-four (5.0%) patients had a clinically significant intracranial haemorrhage. Thirteen patients (2.7%) presented a non-clinically significant brain injury. A total of 37 (7.8%) brain injured patients were included in our study. S100B median value (Q1–Q3) was: 0.043 µg/L (0.008–0.080) for patients with clinically important brain injury versus 0.039 µg/L (0.023–0.059) for patients without clinically important brain injury. Sensitivity and specificity of the S100B protein level, if used alone to detect clinically important brain injury, were 16.7% (95% CI 4.7% to 37.4%) and 88.5% (95% CI 85.2% to 91.3%), respectively.

Conclusion

Plasma S100B protein level was not associated with clinically significant intracranial lesion in patients with mTBI.

Relationship Between Pain, Opioid Treatment, and Delirium in Older Emergency Department Patients

OBJECTIVES

Emergency department (ED) stay and its associated conditions (immobility, inadequate hydration and nutrition, lack of stimulation) increase the risk of delirium in older patients. Poorly controlled pain and paradoxically opioid pain treatment have also been identified as triggers for delirium. The aim of this study was to assess the relationship between pain, opioid treatment, and delirium in older ED patients.

METHODS

A multicenter prospective cohort study was conducted in four hospitals across the province of Québec (Canada). Patients aged ≥ 65 years old, waiting for hospital admission between March and July 2015, who were nondelirious upon ED arrival, who were independent or semi-independent in their daily living activities, and who had an ED stay of at least 8 hours were included. Delirium assessments were conducted twice a day during the patient's entire ED stay and their first 24 hours on the hospital ward using the Confusion Assessment Method. Pain intensity was evaluated using a visual analog scale (VAS = 0-100) during the initial interview, and all opioid treatments were documented.

RESULTS

A total of 338 patients were included; 51% were female, and mean (±SD) age was 77 (±8) years. Forty-one patients (12%) experienced delirium during their hospital stay occurring within a mean (±SD) delay of 47 (±19) hours after ED admission. Among patients with pain intensity ≥ 65 from VAS (0-100), 26% experienced delirium compared to 11% for patients with pain < 65 (p < 0.01), and no significant association was found between opioid consumption and delirium (p = 0.31). Logistic regression controlling for confounding factors showed that patients with pain intensity ≥ 65 are 3.3 (95% confidence interval = 1.4 to 7.9) times more likely to develop delirium than patients who had pain intensity of <65.

CONCLUSIONS

Severe pain, not opioids, is associated with the development of delirium during ED stay. Adequate pain control during the hospital stay may contribute to a decrease in delirium episodes.

Post-discharge respiratory outcomes of children with acute respiratory distress syndrome

OBJECTIVES

While long-term sequelae of acute respiratory distress syndrome (ARDS) are well-documented in adults, few studies reported post-discharge respiratory complications in pediatric ARDS (PARDS) and none used the recent Pediatric Acute Lung Injury Consensus Conference (PALICC) diagnostic criteria. This study describes the respiratory symptoms, pulmonary function, and health resource use of PARDS survivors at 3 months post-discharge.

DESIGN

Retrospective study.

PATIENT SELECTION

Children less than 18 years admitted to the intensive care unit of Sainte-Justine University Health Center from 1st September 2015 to 1st July 2017, and meeting PALICC diagnostic criteria for PARDS.

METHODS

We evaluated 38 of the 44 children with PARDS in the follow-up clinic at a mean (SD) of 3.4 (2.0) months post-discharge for respiratory symptoms, age-appropriate pulmonary function tests (spirometry or oscillometry, maximal respiratory pressures), and all-cause emergency department (ED) visits or rehospitalizations since discharge.

RESULTS

Fourteen (36.8%) had abnormal respiratory symptoms (most commonly cough between respiratory infections and wheezing), 7 of whom (18.4%) presented new respiratory symptoms since PARDS diagnosis. A mild-to-moderate restrictive pattern was observed in 3 of 10 patients who performed spirometry and mildly decreased maximal inspiratory pressures were noted in 2 of 8 patients who performed these maneuvers. Nine (23.7%) patients consulted in the ED and 4 (10.5%) were rehospitalized post-discharge.

CONCLUSIONS

Despite our cohort's limited sample size, our findings suggest that a significant proportion of PARDS survivors experience abnormal respiratory symptoms, pulmonary function deficits, and recurrent problems requiring medical attention. Larger, multicenter studies are required to identify risk factors associated with poor post-discharge outcomes among PARDS survivors.

Serial Ottawa 3DY assessments to detect delirium in older emergency department community dwellers

BACKGROUND

delirium is associated with increased morbidity and mortality among older emergency department (ED) patients. When using physician gestalt, delirium is missed in the majority of patients. The Ottawa 3DY (O3DY) has been validated to detect cognitive dysfunction among older ED patients.

OBJECTIVES

to determine the sensitivity and specificity of serial O3DY assessments to detect delirium in older ED patients.

DESIGN

a prospective observational multicenter cohort study.

SETTING

four Quebec EDs.

PARTICIPANTS

independent or semi-independent older patients (age ≥ 65 years) with an ED stay of at least 8 hours that required hospitalisation.

MEASUREMENTS

eligible patients were evaluated using serial O3DY assessments at least 6 hours apart. The primary outcome was delirium after at least 8 hours in the ED. The reference standard for delirium assessment was the confusion assessment method (CAM). The sensitivity and specificity of the serial O3DY to detect delirium were calculated.

RESULTS

we enrolled 301 patients (mean age 77 years, 49.5% male, 3.0% with a history of mild dementia). Thirty patients (10.0%) were CAM positive for delirium. Patients had a median of three O3DY assessments. Serial O3DY evaluations to detect delirium among patients with at least one abnormal O3DY had a sensitivity of 86.7% (95% confidence interval-CI 69.3-96.2%) and a specificity of 44.3% (95%; CI 38.3-50.4%).

CONCLUSION

serial O3DY testing demonstrates good sensitivity as a screening tool to detect delirium among older adult patients with prolonged ED lengths of stay. Emergency physicians should consider the use of the serial O3DY over clinician gestalt to improve delirium detection.

Acceptability of older patients' self-assessment in the Emergency Department (ACCEPTED)-a randomised cross-over pilot trial

BACKGROUND

patient self-assessment using electronic tablet could improve the quality of assessment of older Emergency Department(ED) patients. However, the acceptability of this practice remains unknown.

OBJECTIVE

to compare the acceptability of self-assessment using a tablet in the ED to a standard assessment by a research assistant (RA), according to seniors and their caregivers.

DESIGN

randomised crossover pilot study.

SETTING

The Hôpital de l'Enfant-Jésus (CHU de Québec-Université Laval) (2018/05-2018/07).

SUBJECTS

(1) ED patients aged ≥65, (2) their caregiver, if present.

METHODS

participants' frailty, cognitive and functional status were assessed with the Clinical Frailty scale, Montreal Cognitive Assessment, and Older American Resources and Services scale and patients self-assessed using a tablet. Test administration order was randomised. The primary outcome, acceptability, was measured using the Treatment Acceptability and Preferences (TAP) scale. Descriptive analyses were performed for sociodemographic variables. TAP scores were adjusted using multivariate linear regression. Thematic content analysis was performed for qualitative data.

RESULTS

sixty-seven patients were included. Mean age was 75.5 ± 8.0 and 55.2% were women. Adjusted TAP scores for RA evaluation and patient self-assessment were 2.36 and 2.20, respectively (P = 0.08). Patients aged ≥85 showed a difference between the TAP scores (P < 0.05). Qualitative data indicates that this might be attributed to the use of technology. Data from nine caregivers showed a 2.42 mean TAP score for RA evaluation and 2.44 for self-assessment.

CONCLUSIONS

our results show that older patients believe self-assessment in the ED using an electronic tablet as acceptable as a standard evaluation by a research assistant. Patients aged ≥85 find this practice less acceptable.

Incidence of delirium in the Canadian emergency department and its consequences on hospital length of stay: a prospective observational multicentre cohort study

OBJECTIVE

We aim to determine the incidence of delirium and describe its impacts on hospital length of stay (LOS) among non-delirious community-dwelling older adults with an 8-hour exposure to the emergency department (ED) environment.

DESIGN

This is a prospective observational multicentre cohort study (March-July 2015). Patients were assessed two times per day during their entire ED stay and up to 24 hours on hospital ward.

SETTING

The study took place in four Canadian EDs.

PARTICIPANTS

338 included patients: (1) aged ≥65 years; (2) who had an ED stay ≥8 hours; (3) were admitted to hospital ward and (4) were independent/semi-independent.

MAIN OUTCOMES AND MEASURES

The primary outcomes of this study were incident delirium in the ED or within 24 hours of ward admission and ED and hospital LOS. Functional and cognitive status were assessed using validated Older Americans Resources and Services and the modified Telephone Interview for Cognitive Status tools. The Confusion Assessment Method was used to detect incident delirium. Univariate and multivariate analyses were conducted to evaluate outcomes.

RESULTS

Mean age was 76.8 (±8.1), 17.7% were aged >85 years old and 48.8% were men. The mean incidence of delirium was 12.1% (n=41). Median IQR ED LOS was 32.4 (24.5-47.9) hours and hospital LOS was 146.6 (75.2-267.8) hours. Adjusted mean hospital LOS was increased by 105.4 hours (4.4 days) (95% CI 25.1 to 162.0, P<0.001) for patients who developed an episode of delirium compared with non-delirious patient.

CONCLUSIONS

An incident delirium was observed in one of eight independent/semi-independent older adults after an 8-hour ED exposure. An episode of delirium increases hospital LOS by 4 days and therefore has important implications for patients and could contribute to ED overcrowding through a deleterious feedback loop.

Clinical prediction rule for delayed hemothorax after minor thoracic injury: a multicentre derivation and validation study

BACKGROUND

About 75% of patients with minor thoracic injury are discharged after an emergency department visit. However, complications such as delayed hemothorax can occur. We sought to derive and validate a clinical decision rule to predict hemothorax in patients discharged from the emergency department.

METHODS

We conducted a 6-year prospective cohort study in 4 university-affiliated emergency departments. Patients aged 16 years or older presenting with a minor thoracic injury were assessed at 5 time points (initial visit and 7, 14, 30 and 90 d after the injury). Radiologists' reports were reviewed for the presence of hemothorax. We used log-binomial regression models to identify predictors of hemothorax.

RESULTS

A total of 1382 patients were included: 830 in the derivation phase and 552 in the validation phase. Of these, 151 (10.9%) had hemothorax at the 14-day follow-up. Patients 65 years of age or older represented 25.3% (210/830) and 23.7% (131/552) of the derivation and validation cohorts, respectively. The final clinical decision rule included a combination of age (> 70 yr, 2 points; 45-70 yr, 1 point), fracture of any high to mid thorax rib (ribs 3-9, 2 points) and presence of 3 or more rib fractures (1 point). Twenty (30.8%) of the 65 high-risk patients (score ≥ 4) experienced hemothorax during the follow-up period. The clinical decision rule had a high specificity (90.7%, 95% confidence interval 87.7%-93.1%) in this high-risk group, thus guiding appropriate post-emergency care.

INTERPRETATION

One patient out of every 10 presented with delayed hemothorax after discharge from the emergency department. Implementation of this validated clinical decision rule for minor thoracic injury could guide emergency discharge plans.

Emergency Department Stay Associated Delirium in Older Patients

BACKGROUND

Caring for older patients can be challenging in the Emergency Department (ED). A > 12 hr ED stay could lead to incident episodes of delirium in those patients. The aim of this study was to assess the incidence and impacts of ED-stay associated delirium.

METHODS

A historical cohort of patients who presented to a Canadian ED in 2009 and 2011 was randomly constituted. Included patients were aged ≥ 65 years old, admitted to any hospital ward, non-delirious upon arrival and had at least a 12-hour ED stay. Delirium was detected using a modified chart-based Confusion Assessment Method (CAM) tool. Hospital length of stay (LOS) was log-transformed and linear regression assessed differences between groups. Adjustments were made for age and comorbidity profile.

RESULTS

200 records were reviewed, 55.5% were female, median age was 78.9 yrs (SD:7.3). 36(18%) patients experienced ED-stay associated delirium. Nearly 50% of episodes started in the ED and within 36 hours of arrival. Comorbidity profile was similar between the positive CAM group and the negative CAM group. Mean adjusted hospital LOS were 20.5 days and 11.9 days respectively (p<.03).

CONCLUSIONS

1 older adult out of 5 became delirious after a 12 hr ED stay. Since delirium increases hospital LOS by more than a week, better screening and implementation of preventing measures for delirium could reduce LOS and overcrowding in the ED.

Occupancy measurement in building: A litterature review, application on an energy efficiency research demonstrated building

Measuring the energy efficiency of buildings and its confrontation with the current Building Energy Simulations now faces knowledge of what is commonly called “occupancy”. This work has been made in order to implement a monitoring system on a research demonstrator building at DLRCA in Angers (France). The goals were first to know the occupancy as input data of models but also to build occupancy models. Occupancy can be defined as all the action of occupants that affect building energy efficiency. The chosen monitoring deals with its presence, lightning, windows opening and internal gains. It seems that the use of an Infra- red detector allows a accuracy of 5 min in the detection of presence. The use of dry contact sensors allows the detection of five different rates of slide windows opening that can affect temperature decrease. Light sensors seem to be efficient to detect artificial lighting states when correctly configured.

Polarization switching in a planar optical waveguide

The multiscale expansion formalism is applied to the study of nonlinear planar optical waveguides. It allows us to describe the linear and nonlinear propagation for both transverse electric and transverse magnetic modes, and the interaction between them. An accurate computation of the nonlinear self- and cross-phase modulation coefficients allows one to give account of the polarization switching which has been observed experimentally.

Effects of speaking rate on the control of vocal fold vibration: clinical implications of active and passive aspects of devoicing

Stevens (1991) has suggested that, while speakers control glottal apertures in producing consonants, the buildup of intraoral pressure during an oral closure creates decreases in transglottal flow, which can, in itself, reduce or halt vocal fold vibrations. The object of this study was to determine whether speakers can take advantage of such pressure effects in controlling the voicing attributes of intervocalic stops. Intraoral pressure, vocal fold vibration (Lx portions of electroglottograms), and electromyographic (EMG) activity of the orbicularis oris inferior were monitored for 6 subjects while they produced at "slow," "normal," and "fast" speaking rates utterances containing intervocalic stops /p/ and /b/. Product-moment correlations between the intervocalic pressure rises and the amplitude contour of Lx showed strong negative relationships at normal-to-fast rates of speech. However, this relationship was not maintained at slower rates, where decreases in the amplitude of Lx sometimes occurred before the onset of EMG activity in the labial adductor. The findings suggest that, at normal-to-fast rates of speech, speakers can use the passive effects of pressure in controlling vocal fold vibration for stop consonants.

Expression of human CD4 in transgenic mice does not confer sensitivity to human immunodeficiency virus infection

Transfection of the human CD4 molecule into mouse cells does not confer susceptibility to human immunodeficiency virus type 1 (HIV-1) infection. Expression of the human CD4 molecule in transgenic mice was seen to offer some new possibilities. However, transgenic mouse T cells expressing either the human CD4 receptor, or a hybrid human/mouse CD4 receptor alone or in conjunction with human major histocompatibility complex class I molecules, were refractory to in vitro HIV-1 infection. In addition, no infection was observed after in vivo HIV inoculation to mice of these various transgenic lines. Injection of recombinant gp160 viral protein to the transgenic mice did not alter their T and B cell populations. The existence of a dominant block in mouse cells that prevents HIV entry is discussed.