Noninvasive assessment of asthma severity using pulse oximeter plethysmograph estimate of pulsus paradoxus physiology

<p>Abstract</p> <p>Background</p> <p>Pulsus paradoxus estimated by dynamic change in area under the oximeter plethysmograph waveform (PEP) might provide a measure of acute asthma severity. Our primary objective was to determine how well PEP correlates with forced expiratory volume in 1-second (%FEV₁) (criterion validity) and change of %FEV₁(responsiveness) during treatment in pediatric patients with acute asthma exacerbations.</p> <p>Methods</p> <p>We prospectively studied subjects 5 to 17 years of age with asthma exacerbations. PEP, %FEV₁, airway resistance and accessory muscle use were recorded at baseline and at 2 and 4 hours after initiation of corticosteroid and bronchodilator treatments. Statistical associations were tested with Pearson or Spearman rank correlations, logistic regression using generalized estimating equations, or Wilcoxon rank sum tests.</p> <p>Results</p> <p>We studied 219 subjects (median age 9 years; male 62%; African-American 56%). Correlation of PEP with %FEV₁demonstrated criterion validity (r = - 0.44, 95% confidence interval [CI], - 0.56 to - 0.30) and responsiveness at 2 hours (r = - 0.31, 95% CI, - 0.50 to - 0.09) and 4 hours (r = - 0.38, 95% CI, - 0.62 to - 0.07). PEP also correlated with airway resistance at baseline (r = 0.28 for ages 5 to 10; r = 0.45 for ages 10 to 17), but not with change over time. PEP was associated with accessory muscle use (OR 1.16, 95% CI, 1.11 to 1.21, P < 0.0001).</p> <p>Conclusions</p> <p>PEP demonstrates criterion validity and responsiveness in correlations with %FEV₁. PEP correlates with airway resistance at baseline and is associated with accessory muscle use at baseline and at 2 and 4 hours after initiation of treatment. Incorporation of this technology into contemporary pulse oximeters may provide clinicians improved parameters with which to make clinical assessments of asthma severity and response to treatment, particularly in patients who cannot perform spirometry because of young age or severity of illness. It might also allow for earlier recognition and improved management of other disorders leading to elevated pulsus paradoxus.</p

The added value of C-reactive protein to clinical signs and symptoms in patients with obstructive airway disease: results of a diagnostic study in primary care

BACKGROUND: To evaluate the diagnostic accuracy of clinical signs and symptoms, C-reactive protein (CRP) and spirometric parameters and determine their interrelation in patients suspected to have an obstructive airway disease (OAD) in primary care. METHODS: In a cross sectional diagnostic study, 60 adult patients coming to the general practitioner (GP) for the first-time with complaints suspicious for obstructive airway disease (OAD) underwent spirometry. Peak expiratory flow (PEF)-variability within two weeks was determined in patients with inconspicuous spirometry. Structured medical histories were documented and CRP was measured. The reference standard was the Tiffeneau ratio (FEV(1)/VC) in spirometry and the PEF-variability. OAD was diagnosed when FEV(1)/VC ≤ 70% or PEF-variability > 20%. RESULTS: 37 (62%) patients had OAD. The best cut-off value for CRP was found at 2 mg/l with a diagnostic odds ratio (OR) of 4.4 (95% CI 1.4–13.8). Self-reported wheezing was significantly related with OAD (OR 3.4; CI 1.1–10.3), whereas coughing was inversely related (OR 0.2; CI 0.1–0.7). The diagnostic OR of CRP increased when combined with dyspnea (OR 8.5; 95% CI 1.7–42.3) or smoking history (OR 8.4; 95% CI 1.5–48.9). CRP (p = 0.004), FEV(1 )(p = 0.001) and FIV(1 )(p = 0.023) were related with the severity of dyspnea. CRP increased with the number of cigarettes, expressed in pack years (p = 0.001). CONCLUSION: The diagnostic accuracy of clinical signs and symptoms was low. The diagnostic accuracy of CRP improved in combination with dyspnea and smoking history. Due to their coherence with the severity of dyspnea and number of cigarettes respectively, CRP and spirometry might allow risk stratification of patients with OAD in primary care. Further studies need to be done to confirm these findings

Accuracy of History, Wheezing, and Forced Expiratory Time in the Diagnosis of Chronic Obstructive Pulmonary Disease

OBJECTIVE: To determine the accuracy of the history and selected elements of the physical examination in the diagnosis of chronic obstructive pulmonary disease (COPD). DESIGN: Independent blind comparison of the standard clinical examination (evaluating the accuracy of history, wheezing, and forced expiratory time [FET]) with spirometry. The gold standard for diagnosis of COPD was a forced expiratory volume at 1 second (FEV(1)) below the fifth percentile (adjusted for patient height and age). SETTING: Seven sites in 6 countries, including investigators from primary care and secondary care settings. PARTICIPANTS: One hundred sixty-one consecutive patients with varying severity of disease (known COPD, suspected COPD, or no COPD) participated in the study. MAIN RESULTS: One hundred sixty-one patients (mean age 65 years, 39% female, 41% with known COPD, 27% with suspected COPD, and 32% normal) were recruited. Mean (±SD) FEV(1) and forced vital capacity were 1,720 (±830) mL and 2,520 (±970) mL. The likelihood ratios (LR) for the tested elements of the clinical examination (and their P values on χ2 testing) were: self-reported history of COPD, 5.6 (P < .001); FET greater than 9 seconds, 6.7 (P < 0.01); smoked longer than 40 pack years, 3.3 (P = .001); wheezing, 4.0 (P < .001); male gender, 1.6 (P < .001); and age over 65 years, 1.6 (P = .025). The accuracy of these elements was not appreciably different when reference standards other than FEV(1) below the 5th percentile were applied. Only 3 elements of the clinical examination were significantly associated with the diagnosis of COPD on multivariate analysis: self-reported history of COPD (adjusted LR 4.4), wheezing (adjusted LR 2.9), and FET greater than 9 seconds (adjusted LR 4.6). Area under the receiver operating characteristic curve for the model incorporating these 3 factors was 0.86. CONCLUSIONS: Less emphasis should be placed on the presence of isolated symptoms or signs in the diagnosis of COPD. While numerous elements of the clinical examination are associated with the diagnosis of COPD, only 3 are significant on multivariate analysis. Patients having all 3 of these findings have an LR of 33 (ruling in COPD); those with none have an LR of 0.18 (ruling out COPD)

Selective Chemical Vapor Deposition

Selective area deposition has received much attention in IC technology in the past forty years. Its advantage in IC technology is that one saves a mask and a full sequence of lithography, etching, resist removal and cleaning. In Selective Chemical Vapor Deposition (CVD) the selectivity is obtained by the different chemical behavior of reactants with different surfaces. The advantage of selective CVD is the self-alignment with respect to the previous pattern, which allows for tight design-rules in this phase of the IC production. Selective epitaxial Silicon deposition was investigated in the sixties of the last century. Later selective Tungsten, selective epitaxial SiGe, selective IH-V and II-VI compounds and recently selective deposition of Copper became intensively researched subjects. In these cases of selective deposition one etches a window in a dielectric to the substrate and then deposits the required layer. Due to nucleation matters it starts to grow immediately on the substrate material whereas the nucleation on the dielectric is retarded. However, in nature one never gets advantages for free. Selectivity loss, reaction with the substrate material, facetting, lateral overgrowth on the dielectric and pattern-density dependency are major problems

Acurácia do exame clínico no diagnóstico da DPOC Accuracy of clinical examination findings in the diagnosis of COPD

OBJETIVO: A DPOC é um problema de saúde pública, e métodos diagnósticos simples podem ser úteis para facilitar o diagnóstico desta doença. O objetivo deste estudo foi avaliar a acurácia de variáveis clínicas para o diagnóstico de DPOC. MÉTODOS: Pacientes com DPOC e controles foram prospectivamente avaliados por dois examinadores quanto a nove variáveis clínicas. A razão de verossimilhança para o diagnóstico de DPOC foi determinada utilizando-se o modelo de regressão logística. RESULTADOS: Foram incluídos 98 pacientes com DPOC (idade média, 62,3 ± 12,3 anos; VEF1 médio, 48,3 ± 21,6%) e 102 controles. A razão de verossimilhança e IC95% para o diagnóstico de DPOC foram: 4,75 (2,29-9,82; p < 0,0001) para uso da musculatura acessória; 5,05 (2,72-9,39; p < 0,0001) para respiração com os lábios semicerrados; 2,58 (1,45-4,57; p < 0,001) para tórax em barril; 3,65 (2,01-6,62; p < 0,0001) para redução da expansibilidade torácica; 7,17 (3,75-13,73; p < 0,0001) para redução do murmúrio vesicular; 2,17 (1,01-4,67; p < 0,05) para índice torácico > 0,9; 2,36 (1,22-4,58; p < 0,05) para comprimento laríngeo < 5,5 cm; 3,44 (1,92-6,16; p < 0,0001) para tempo expiratório forçado > 4 s; e 4,78 (2,13-10,70; p < 0.0001) para limite inferior do fígado > 4 cm abaixo do rebordo costal. A concordância entre observadores para as mesmas variáveis foi, respectivamente, 0,57, 0,45, 0,62, 0,32, 0,53, 0,32, 0,59, 0,52 e 0,44 (p < 0,0001 para todas). CONCLUSÕES: Vários achados do exame clínico podem ser utilizados como testes diagnósticos para DPOC.<br>OBJECTIVE: Simple diagnostic methods can facilitate the diagnosis of COPD, which is a major public health problem. The objective of this study was to investigate the accuracy of clinical variables in the diagnosis of COPD. METHODS: Patients with COPD and control subjects were prospectively evaluated by two investigators regarding nine clinical variables. The likelihood ratio for the diagnosis of COPD was determined using a logistic regression model. RESULTS: The study comprised 98 patients with COPD (mean age, 62.3± 12.3 years; mean FEV1, 48.3 ± 21.6%) and 102 controls. The likelihood ratios (95% CIs) for the diagnosis of COPD were as follows: 4.75 (2.29-9.82; p < 0.0001) for accessory muscle recruitment; 5.05 (2.72-9.39; p < 0.0001) for pursed-lip breathing; 2.58 (1.45-4.57; p < 0.001) for barrel chest; 3.65 (2.01-6.62; p < 0.0001) for decreased chest expansion; 7.17 (3.75-13.73; p < 0.0001) for reduced breath sounds; 2.17 (1.01-4.67; p < 0.05) for a thoracic index > 0.9; 2.36 (1.22-4.58; p < 0.05) for laryngeal height < 5.5 cm; 3.44 (1.92-6.16; p < 0.0001) for forced expiratory time > 4 s; and 4.78 (2.13-10.70; p < 0.0001) for lower liver edge > 4 cm from lower costal edge. Inter-rater reliability for those same variables was, respectively, 0.57, 0.45, 0.62, 0.32, 0.53, 0.32, 0.59, 0.52 and 0.44 (p < 0.0001 for all). CONCLUSIONS: Various clinical examination findings could be used as diagnostic tests for COPD