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PURPOSE: Haptic repositioning during flanged intraocular lens (IOL) fixation can be difficult, and the haptic requiring repositioning may be at increased risk of excessive bending or breakage. This study aimed to report double-needle haptic repositioning technique outcomes for the aforementioned difficulty during flanged IOL fixation. METHODS: This retrospective case series included seven eyes requiring haptic repositioning during flanged IOL fixation. The method features reinsertion of an already externalized haptic into the needle lumen followed by a needle-haptic complex internalized through the original tract into the eyeball. Thus, an adequate configuration for contralateral haptic can be achieved for insertion into the needle lumen to create a double-needle condition before both haptics are successfully externalized. RESULTS: The median follow-up duration was 24 months (range, 4-24 months). Postoperatively, the IOL was well-centered, and corrected distance visual acuity improved from 20/320 (20/4,000-20/70) to 20/50 (20/250-20/20). No intraoperative or postoperative complications were noted. CONCLUSION: The technique produced encouraging results in patients undergoing haptic repositioning during flanged IOL fixation. This technique could potentially reduce haptic overbending risk and facilitate haptic adjustment. Further studies are needed to confirm the feasibility of the technique.
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Implante de Lente Intraocular , Lentes Intraoculares , Humanos , Implante de Lente Intraocular/métodos , Estudos Retrospectivos , Tecnologia Háptica , Esclera/cirurgia , Técnicas de SuturaRESUMO
OBJECTIVES: Little is known about the recent status of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in the U.S. emergency department (ED). This study aimed to describe the disease burden (visit and hospitalization rate) of AECOPD in the ED and to investigate factors associated with the disease burden of AECOPD. METHODS: Data were obtained from the National Hospital Ambulatory Medical Care Survey (NHAMCS), 2010-2018. Adult ED visits (aged 40 years or above) with AECOPD were identified using International Classification of Diseases codes. Analysis used descriptive statistics and multivariable logistic regression accounting for NHAMCS's complex survey design. RESULTS: There were 1,366 adult AECOPD ED visits in the unweighted sample. Over the 9-year study period, there were an estimated 7,508,000 ED visits for AECOPD, and the proportion of AECOPD visits in the entire ED population remained stable at approximately 14 per 1,000 visits. The mean age of these AECOPD visits was 66 years, and 42% were men. Medicare or Medicaid insurance, presentation in non-summer seasons, the Midwest and South regions (vs. Northeast), and arrival by ambulance were independently associated with a higher visit rate of AECOPD, whereas non-Hispanic black or Hispanic race/ethnicity (vs. non-Hispanic white) was associated with a lower visit rate of AECOPD. The proportion of AECOPD visits that were hospitalized decreased from 51% to 2010 to 31% in 2018 (p = 0.002). Arrival by ambulance was independently associated with a higher hospitalization rate, whereas the South and West regions (vs. Northeast) were independently associated with a lower hospitalization rate. The use of antibiotics appeared to be stable over time, but the use of systemic corticosteroids appeared to increase with near statistical significance (p = 0.07). CONCLUSIONS: The number of ED visits for AECOPD remained high; however, hospitalizations for AECOPD appeared to decrease over time. Some patients were disproportionately affected by AECOPD, and certain patient and ED factors were associated with hospitalizations. The reasons for decreased ED admissions for AECOPD deserve further investigation.
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Medicare , Doença Pulmonar Obstrutiva Crônica , Adulto , Masculino , Humanos , Idoso , Estados Unidos/epidemiologia , Feminino , Doença Pulmonar Obstrutiva Crônica/epidemiologia , Doença Pulmonar Obstrutiva Crônica/terapia , Hospitalização , Serviço Hospitalar de Emergência , Classificação Internacional de DoençasRESUMO
STUDY OBJECTIVE: The effect of out-of-hospital intubation in patients with out-of-hospital cardiac arrest remains controversial. The Taipei City paramedics are the earliest authorized to perform out-of-hospital intubation among Asian areas. This study evaluates the association between successful intubation and out-of-hospital cardiac arrest survival in Taipei. METHODS: We analyzed 6 years of Utstein-based registry data from nontrauma adult patients with out-of-hospital cardiac arrest who underwent out-of-hospital airway management including intubation, laryngeal mask airway, or bag-valve-mask ventilation. The primary analysis was intubation success on patient outcomes. The primary outcome was survival to discharge and the secondary outcomes included sustained return of spontaneous circulation and favorable neurologic survival. Sensitivity analysis was performed with intubation attempts rather than intubation success. Subgroup analysis of advanced life support-serviced districts was also performed. RESULTS: A total of 10,853 cases from 2008 to 2013 were analyzed. Among out-of-hospital cardiac arrest patients receiving airway management, successful intubation, laryngeal mask airway, and bag-valve-mask ventilation was reported in 1,541, 3,099, and 6,213 cases, respectively. Compared with bag-valve-mask device use, successful out-of-hospital intubation was associated with improved chances of sustained return of spontaneous circulation (adjusted odds ratio [aOR] 1.91; 95% confidence interval [CI] 1.66 to 2.19), survival to discharge (aOR 1.98; 95% CI 1.57 to 2.49), and favorable neurologic outcome (aOR 1.44; 95% CI 1.03 to 2.03). The results were comparable in sensitivity and subgroup analyses. CONCLUSION: In nontrauma adult out-of-hospital cardiac arrest in Taipei, successful out-of-hospital intubation was associated with improved odds of sustained return of spontaneous circulation, survival to discharge, and favorable neurologic outcome.
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Manuseio das Vias Aéreas/métodos , Reanimação Cardiopulmonar/métodos , Serviços Médicos de Emergência/métodos , Intubação Intratraqueal/métodos , Parada Cardíaca Extra-Hospitalar/terapia , Sistema de Registros , População Urbana , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Parada Cardíaca Extra-Hospitalar/mortalidade , Estudos Retrospectivos , Taxa de Sobrevida/tendências , Taiwan/epidemiologia , Fatores de Tempo , Resultado do TratamentoRESUMO
OBJECTIVE: The prehospital termination of resuscitation (TOR) guidelines for traumatic cardiopulmonary arrest (TCPA) was proposed in 2003. Its multiple descriptors of cases where efforts can be terminated make it complex to apply in the field. Here we proposed a simplified rule and evaluated its predictive performance. METHODS: We analysed Utstein registry data for 2009-2013 from a Taipei emergency medical service to test a simplified TOR rule that comprises two criteria: blunt trauma injury and the presence of asystole. Enrolees were adults (≥18â years) with TCPA. The predicted outcome was in-hospital death. We compared the areas under the curve (AUC) of the simple rule with each of four descriptors in the guidelines and with a combination of all four to assess their discriminatory ability. Test characteristics were calculated to assess predictive performance. RESULTS: A total of 893 TCPA cases were included. Blunt trauma occurred in 459 (51.4%) cases and asystole in 384 (43.0%). In-hospital mortality was 854 (95.6%) cases. The simplified TOR rule had greater discriminatory ability (AUC 0.683, 95% CI 0.618 to 0.747) compared with any single descriptor in the 2003 guidelines (range of AUC: 0.506-0.616) although the AUC was similar when all four were combined (AUC 0.695, 95% CI 0.615 to 0.775). The specificity of the simplified rule was 100% (95% CI 88.8% to 100%) and positive predictive value 100% (95% CI 96.8% to 100%). The false positive value, false negative value and decreased rate of unnecessary transport were 0% (95% CI 0% to 3.2%), 94.8% (95% CI 92.9% to 96.2%) and 16.4% (95% CI 14.1% to 19.1%), respectively. CONCLUSIONS: The simplified TOR rule appears to accurately predict non-survivors in adults with TCPA in the prehospital setting.
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Reanimação Cardiopulmonar/normas , Serviços Médicos de Emergência/normas , Parada Cardíaca Extra-Hospitalar/terapia , Ordens quanto à Conduta (Ética Médica) , Técnicas de Apoio para a Decisão , Feminino , Mortalidade Hospitalar , Humanos , Masculino , Pessoa de Meia-Idade , Parada Cardíaca Extra-Hospitalar/mortalidade , Guias de Prática Clínica como Assunto , Prognóstico , Sistema de Registros , Sensibilidade e Especificidade , Taxa de Sobrevida , Ferimentos e Lesões/complicaçõesRESUMO
Background: Emergency department cardiac arrest (EDCA) is a global public health challenge associated with high mortality rates and poor neurological outcomes. This study aimed to describe the incidence, risk factors, and causes of EDCA during emergency department (ED) visits in the U.S. Methods: This retrospective cohort study used data from the 2019 Nationwide Emergency Department Sample (NEDS). Adult ED visits with EDCA were identified using the cardiopulmonary resuscitation code. We used descriptive statistics and multivariable logistic regression, considering NEDS's complex survey design. The primary outcome measure was EDCA incidence. Results: In 2019, there were approximately 232,000 ED visits with cardiac arrest in the U.S. The incidence rate of EDCA was approximately 0.2%. Older age, being male, black race, low median household income, weekend ED visits, having Medicare insurance, and ED visits in non-summer seasons were associated with a higher risk of EDCA. Hispanic race was associated with a lower risk of EDCA. Certain comorbidities (e.g., diabetes and cancer), trauma centers, hospitals with a metropolitan and/or teaching program, and hospitals in the South were associated with a higher risk of EDCA. Depression, dementia, and hypothyroidism were associated with a lower risk of EDCA. Septicemia, acute myocardial infarction, and respiratory failure, followed by drug overdose, were the predominant causes of EDCA. Conclusions: Some patients were disproportionately affected by EDCA. Strategies should be developed to target these modifiable risk factors, specifically factors within ED's control, to reduce the subsequent disease burden.
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Transferring patients between emergency departments (EDs) is a complex but important issue in emergency care regionalization. Social network analysis (SNA) is well-suited to characterize the ED transfer pattern. We aimed to unravel the underlying transfer network structure and to identify key network metrics for monitoring network functions. This was a retrospective cohort study using the National Electronic Referral System (NERS) database in Taiwan. All interhospital ED transfers from 2014 to 2016 were included and transfer characteristics were retrieved. Descriptive statistics and social network analysis were used to analyze the data. There were a total of 218,760 ED transfers during the 3-year study period. In the network analysis, there were a total of 199 EDs with 9516 transfer ties between EDs. The network demonstrated a multiple hub-and-spoke, regionalized pattern, with low global density (0.24), moderate centralization (0.57), and moderately high clustering of EDs (0.63). At the ED level, most transfers were one-way, with low reciprocity (0.21). Sending hospitals had a median of 5 transfer-out partners [interquartile range (IQR) 3-7), while receiving hospitals a median of 2 (IQR 1-6) transfer-in partners. A total of 16 receiving hospitals, all of which were designated base or co-base hospitals, had 15 or more transfer-in partners. Social network analysis of transfer patterns between hospitals confirmed that the network structure largely aligned with the planned regionalized transfer network in Taiwan. Understanding the network metrics helps track the structure and process aspects of regionalized care.
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Transferência de Pacientes , Análise de Rede Social , Humanos , Estudos Retrospectivos , Taiwan , Serviço Hospitalar de EmergênciaRESUMO
Background: Mass casualties caused by natural disasters and man-made events may overwhelm local emergency medical services and healthcare systems. Logistics is essential to a successful emergency medical response. Drills have been used in disaster preparedness to validate plans, policies, procedures, and agreements, and identify resource gaps. The application of the internet to facilitate the conduct of exercise was still limited. This study aimed to investigate the optimal preparation of medical supplies by medical emergency response teams (MERTs) during emergencies and disasters using an internet-based drill. Methods: An internet-based drill based on real-life mass casualty incidents (MCIs) was developed and conducted in Taiwan from June 2017 to July 2018. The drill involved an MCI with 50 events delivered under two scenarios: (1) reduced transfer capacity and well-functioning local healthcare facilities (emergency module); (2) severely reduced transfer capacity and dysfunctional local healthcare facilities (disaster module). For each event, medical supplies commonly prepared by local MERTs in Taiwan were listed in structured questionnaires and participants selected the supplies they would use. Results: Forty-three senior medical emergency responders participated in the survey (responding rate of 47.3%). Resuscitation-related supplies increased from emergency to disaster module (e.g., intubation from 9.1% to 13.9%; dopamine from 3.2% to 5.0%; all p < 0.001). In the subgroup analysis of events with life-threatening injuries, the utilization of resuscitation-related supplies (e.g., intubation from 46.6% to 65.3%; p < 0.001) remained higher in the disaster than in the emergency module. Compared to emergency medical technicians, physicians and nurses are more likely to use intravenous/intramuscular analgesics. Conclusions: The severity of scenarios and the professional background of emergency responders have a different utilization of medical supplies in the simulation drill. The internet-based drill may contribute to optimizing the preparedness of medical response to prehospital emergencies and disasters.
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Little is known about pulmonary embolism (PE) in the United States emergency department (ED). This study aimed to describe the disease burden (visit rate and hospitalization) of PE in the ED and to investigate factors associated with its burden. Data were obtained from the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2010 to 2018. Adult ED visits with PE were identified using the International Classification of Diseases codes. Analyses used descriptive statistics and multivariable logistic regression accounting for the NHAMCS's complex survey design. Over the 9-year study period, there were an estimated 1,500,000 ED visits for PE, and the proportion of PE visits in the entire ED population increased from 0.1% in 2010-2012 to 0.2% in 2017-2018 (P for trend = 0.002). The mean age was 57 years, and 40% were men. Older age, obesity, history of cancer, and history of venous thromboembolism were independently associated with a higher proportion of PE, whereas the Midwest region was associated with a lower proportion of PE. The utilization of chest computed tomography (CT) scan appeared stable, which was performed in approximately 43% of the visits. About 66% of PE visits were hospitalized, and the trend remained stable. Male sex, arrival during the morning shift, and higher triage levels were independently associated with a higher hospitalization rate, whereas the fall and winter months were independently associated with a lower hospitalization rate. Approximately 8.8% of PE patients were discharged with direct-acting oral anticoagulants. The ED visits for PE continued to increase despite the stable trend in CT use, suggesting a combination of prevalent and incident PE cases in the ED. Hospitalization for PE remains common practice. Some patients are disproportionately affected by PE, and certain patient and hospital factors are associated with hospitalization decisions.
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Serviço Hospitalar de Emergência , Embolia Pulmonar , Adulto , Humanos , Masculino , Estados Unidos/epidemiologia , Pessoa de Meia-Idade , Feminino , Embolia Pulmonar/epidemiologia , Hospitalização , Pesquisas sobre Atenção à SaúdeRESUMO
This paper presents an efficient path-planning algorithm for microrobots attempting to pass through environments with narrow passages. Because of the extremely small size of a microrobot, it is suitable for work in this kind of environment. The rapidly exploring random tree (RRT) algorithm, which uses random sampling points, can quickly explore an entire environment and generate a sub-optimal path for a robot to pass through it; however, the RRT algorithm, when used to plan a path for a microrobot passing through an environment with narrow passages, has the problem of being easily limited to local solutions when it confronts with a narrow passage and is unable to find the final path through it. In light of this, the objectives of the considered path planning problem involve detecting the narrow passages, leading the path toward an approaching narrow passage, passing through a narrow passage, and extending the path search more efficiently. A methodology was proposed based on the bidirectional RRT in which image processing is used to mark narrow passages and their entrances and exits so that the bidirectional RRT can be quickly guided to them and combined with the deterministic algorithm to find paths through them. We designed the methodology such that RRT generates the sampling points for path growth. The multiple importance sampling technique is incorporated with bidirectional RRT, named MIS-BiRRT, to make the path grow faster toward the target point and narrow passages while avoiding obstacles. The proposed algorithm also considers multiple candidate paths simultaneously to expand the search range and then retain the best one as a part of the planning path. After validation from simulation, the proposed algorithm was found to generate efficient path planning results for microrobots to pass through narrow passages.
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Objectives: Early recognition and prevention of in-hospital cardiac arrest (IHCA) play an increasingly important role in the Chain of Survival. However, clinical tools for predicting IHCA in the emergency department (ED) are scanty. We sought to evaluate the role of serum lactate in predicting ED-based IHCA. Methods: Data were retrieved from 733,398 ED visits over a 7-year period in a tertiary medical centre. We selected one ED visit per person and excluded out-of-hospital cardiac arrest, children, or those without lactate measurements. Patient demographics, computerised triage information, and serum lactate levels were extracted. The initial serum lactate levels were grouped into normal (≤2 mmol/L), moderately elevated (2 < lactate ≤ 4), and highly elevated (>4 mmol/L) categories. The primary outcome was ED-based IHCA. Results: A total of 17,392 adult patients were included. Of them, 342 (2%) developed IHCA. About 50% of the lactate levels were normal, 30% were moderately elevated, and 20% were highly elevated. In multivariable analysis, the group with highly elevated lactate had an 18-fold increased risk of IHCA (adjusted odds ratio [OR], 18.0; 95% confidence interval [CI], 11.5-28.2), compared with the normal lactate group. In subgroup analysis, the poor lactate-clearance group (<2.5%/h) was associated with a 7.5-fold higher risk of IHCA (adjusted OR, 7.5; 95%CI, 3.7-15.1) compared with the normal clearance group. Conclusions: Elevated lactate levels and poor lactate clearance were strongly associated with a higher risk of ED-based IHCA. Clinicians may consider a more liberal sampling of lactate in patients at higher risk of IHCA with follow-up of abnormal levels.
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BACKGROUND: Termination-of-resuscitation rules (TORRs) in out-of-hospital cardiac arrest (OHCA) patients have been applied in western countries; in Asia, two TORRs were developed and have not been externally validated widely. We aimed to externally validate the TORRs using the registry of Pan-Asian Resuscitation Outcomes Study (PAROS). METHODS: PAROS enrolled 66,780 OHCA patients in seven Asian countries from 1 January 2009 to 31 December 2012. The American Heart Association-Basic Life Support and AHA-ALS (AHA-BLS), AHA-Advanced Life Support (AHA-ALS), Goto, and Shibahashi TORRs were selected. The diagnostic test characteristics and area under the receiver operating characteristic curve (AUC) were calculated. We further determined the most suitable TORR in Asia and analysed the variable differences between subgroups. RESULTS: We included 55,064 patients in the final analysis. The sensitivity, specificity, negative predictive value, positive predictive value, and AUC, respectively, for AHA-BLS, AHA-ALS, Goto, Shibashi TORRs were 79.0%, 80.0%, 19.6%, 98.5%, and 0.80; 48.6%, 88.3%, 9.8%, 98.5%, and 0.60; 53.8%, 91.4%, 11.2%, 99.0%, and 0.73; and 35.0%, 94.2%, 8.4%, 99.0%, and 0.65. In countries using the Goto TORR with PPV<99%, OHCA patients were younger, had more males, a higher rate of shockable rhythm, witnessed collapse, pre-hospital defibrillation, and survival to discharge, compared with countries using the Goto TORR with PPV ≥99%. CONCLUSIONS: There was no single TORR fit for all Asian countries. The Goto TORR can be considered the most suitable; however, a high predictive performance with PPV ≥99% was not achieved in three countries using it (Korea, Malaysia, and Taiwan).
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Reanimação Cardiopulmonar , Serviços Médicos de Emergência , Parada Cardíaca Extra-Hospitalar , Ásia , Estudos Transversais , Humanos , Masculino , Parada Cardíaca Extra-Hospitalar/terapia , Sistema de RegistrosRESUMO
This study aimed to investigate whether early surgical decompression was associated with favorable neurological recovery in patients with traumatic spinal cord injury (tSCI). We searched PubMed and Embase from the database inception through December 2020 and selected studies comparing the impact of early versus late surgical decompression on neurological recovery as assessed by American Spinal Injury Association Impairment Scale (AIS) for adult patients sustaining tSCI. We pooled the effect estimates in random-effects models and quantified the heterogeneity by the I2 statistics. Subgroup analysis and meta-regression analysis was conducted to identify significant outcome moderator. We included 26 studies involving 3574 patients in the meta-analysis. The pooled results demonstrated significant association between early surgical decompression and an improvement of at least one AIS grade (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.41-2.41; I2, 48.06%). The benefits of early surgical decompression were consistently observed across different subgroups, including patients with cervical or thoracolumbar injury and patients with complete or incomplete injury. The meta-regression analysis indicated that cut-off timing defining early versus late decompression was a significant effect moderator, with early decompression performed before post-tSCI 8 or 12 h associated with greatest benefits (OR, 3.37; 95% CI, 1.74-6.50; I2, 53.52%). No obvious publication bias was detected by the funnel plot. In conclusion, early surgical decompression was associated with favorable neurological recovery for tSCI patients. However, there was a lack of high-quality evidence and the results need further examination.
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Descompressão Cirúrgica , Traumatismos da Medula Espinal/cirurgia , Tempo para o Tratamento , Humanos , Recuperação de Função Fisiológica , Resultado do TratamentoRESUMO
Data presented in this article relates to the research article entitled "US-CAB protocol for ultrasonographic evaluation during cardiopulmonary resuscitation: validation and potential impact" (Lien et al., in press). The article provides data regarding proficiency of the 10 emergency residents attending the US-CAB curriculum. Assessments included immediate evaluation at the end of training and re-evaluation 6 months later. A written test, and the ultrasound image acquisition were required in the immediate evaluation The re-evaluation included the written test and performance on the same healthy volunteer.
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BACKGROUND: We previously developed a US-CAB protocol for evaluation of circulatory-airway-breathing status during cardiopulmonary resuscitation (CPR). This study aimed at validating its application in real CPR scenarios and the potential impact on CPR outcomes. METHODS: The US-CAB protocol was implemented at the emergency department of National Taiwan University Hospital since January 2016. The US images, initiation time and operation duration of each US-CAB procedure, and relevant CPR information were recorded for analysis. RESULTS: From January 2016 to March 2017, 177 cardiac arrest patients receiving US-CAB were included. The durations of US-C-A-B procedure were 9.0⯱â¯1.4, 7.5⯱â¯1.5, and 16.0⯱â¯1.9â¯s, respectively. Cardiac activity was identified in 47 cases (26.6%), with higher rates of return of spontaneous circulation (ROSC) (95.7% vs. 21.5%, pâ¯<â¯.0001) and survival to hospital discharge (25.5% vs. 10.0%, pâ¯<â¯.01). Detection of cardiac activity after 10â¯min of CPR exhibited 100% sensitivity, specificity, positive and negative predictive value for ROSC. Cardiac tamponade was noted in eight patients. ROSC was achieved in two (25.0%) after pericardiocentesis, and aortic dissection was diagnosed in one (12.5%). Confirmation of correct intubation was significantly faster by US than by capnography (7.4⯱â¯1.4 vs. 38.3⯱â¯110.2â¯s, pâ¯<â¯.001). US detected 21 (11.9%) esophageal intubations and 3 (1.7%) one-lung intubations. All were promptly corrected. CONCLUSION: The US-CAB protocol is feasible in real CPR scenarios. It confers diagnostic value and prognostic implications which potentially impact the efficacy and outcomes of CPR. However, a future prospective multi-center study to validate its feasibility and indicate the need of structured training is mandated.
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Reanimação Cardiopulmonar/métodos , Serviços Médicos de Emergência/métodos , Parada Cardíaca Extra-Hospitalar/terapia , Idoso , Idoso de 80 Anos ou mais , Manuseio das Vias Aéreas/métodos , Circulação Sanguínea , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Parada Cardíaca Extra-Hospitalar/diagnóstico por imagem , Parada Cardíaca Extra-Hospitalar/mortalidade , Valor Preditivo dos Testes , Estudos Prospectivos , Respiração , Fatores de Tempo , UltrassonografiaRESUMO
Changes in vascular mechanics due to aging include elevated vascular impedance, diminished aorta distensibility, and an accelerated return of pulse wave reflection, which may increase the systolic workload on the heart. Classically, the accurate measurement of vascular mechanics requires the simultaneous recording of aortic pressure and flow signals. In practice, it is feasible to estimate arterial wave properties in terms of wave transit time (τw) and wave reflection index (RI) by using aortic pressure signal alone. In this study, we determined the τ w and magnitudes of the forward (â£Pf â£) and backward (â£Pb â£) pressure waves in Long-Evans male rats aged 4 (n = 14), 6 (n = 17), 12 (n = 17), and 18 (n = 24) months, based on the measured aortic pressure and an assumed triangular flow (Qtri). The pulsatile pressure wave was the only signal recorded in the ascending aorta by using a high-fidelity pressure sensor. The base of the unknown Qtri was constructed using a duration, which equals to the ejection time. The timing at the peak of the triangle was derived using the fourth-order derivative of the aortic pressure waveform. In the 18-month-old rats, the ratio of τ w to left ventricular ejection time (LVET) decreased, indicating a decline in the distensibility of the aorta. The increased â£Pb ⣠associated with unaltered â£Pf ⣠enhanced the RI in the older rats. The augmentation index (AI) also increased significantly with age. A significant negative correlation between the AI and τ w /LVET was observed: AI = -0.7424 - 0.9026 × (τ w /LVET) (r = 0.4901; P < 0.0001). By contrast, RI was positively linearly correlated with the AI as follows: AI = -0.4844 + 2.3634 × RI (r = 0.8423; P < 0.0001). Both the decreased τ w /LVET and increased RI suggested that the aging process may increase the AI, thereby increasing the systolic hydraulic load on the heart. The novelty of the study is that Qtri is constructed using the measured aortic pressure wave to approximate its corresponding flow signal, and that calibration of Qtri is not essential in the analysis.