Marcos Mello Moreira

Alveolar dead space and capnographic variables before and after thrombolysis in patients with acute pulmonary embolism.

Pulmonary embolism (PE) is a common condition. The central aim of this study was to describe the use of volumetric capnography (VCap) before and after fibrinolytic treatment of major PE. Lung scintigraphy was used as a base of comparison for the results of this treatment. We describe the cases of two conscious and spontaneously breathing patients (20- and by 24-year-old women) with major PE undergoing thrombolysis. Curves of CO2 were obtained VCap and associated with arterial blood gas analysis and D-dimer. The pattern of VCap was compared with the VCap of health volunteers. Parameters also calculated were: P(a-et)CO2 gradient, alveolar dead space fraction (AVDSf ), late dead space fraction (fDlate), and slope phase III (Slp III). The VCap results before and after thrombolysis for patients 1 and 2 were, respectively, P(a-et)CO2: 12.6 to 5.8 and 7.9 to 1.6 (mmHg); AVDSf: 0.46 to 0.18 and 0.25 to 0.05; fDlate: 0.46 to 0.21 and 0.24 to 0.04; Slp III: 1.75 to 5.10 and 1.21 to 5.61 (mmHg/L). Lung scintigraphy was used to compare VCap results from the two subjects with VCap results from healthy volunteers and pigs before and after treatment associated with arterial blood gas, D-dimer, and showed satisfactory agreement.

Volumetric capnography as a tool to detect early peripheric lung obstruction in cystic fibrosis patients

OBJECTIVE To compare spirometry and volumetric capnography (VCap) to determine if the capnographic values add more information about early lung disease in cystic fibrosis (CF) patients. METHODS This was a cross-sectional study involving CF patients: Group I (42 patients, 6-12 years of age); and Group II (22 patients, 13-20 years of age). The corresponding control groups were comprised of 30 and 50 healthy subjects, respectively. Forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), and the FEV(1)/FVC ratio was determined by spirometry. Using VCap, we measured peripheral oxygen saturation (SpO(2)), respiratory rate (RR), inspiratory time (IT), expiratory time (ET), and the phase III slope normalized by expiratory volume (phase III slope/Ve). RESULTS In comparison with control groups, all CF patients presented higher phase III slope/Ve values (p < 0.001) independent of the pulmonary disease stage. The phase III slope/Ve was significantly higher in the 24 patients who presented normal spirometry results (p = 0.018). The Group II patients showed lower FVC, FEV(1), FEV(1)/FVC (p < 0.05), and also lower SpO(2) values (p < 0.001) when compared with Group I patients. In comparison with Control Group II, the Group II patients presented higher RR (p < 0.001), and lower IT and ET values (p < 0.001). CONCLUSIONS Compared to the controls, all studied CF patients showed an increase in phase III slope/Ve values. VCap identified the heterogeneity of the ventilation distribution in the peripheral airways of CF patients who presented normal spirometry.

Thrombolysis in massive pulmonary embolism based on the volumetric capnography

This is the first report of a patient submitted to chemical thrombolysis due to massive pulmonary embolism (PE) during the postoperative period of neurosurgery, in whom due to the lack of adequate clinical conditions, no imaging assessment was performed. Clinical, gasometric and capnographic data allowed the decision to perform the thrombolysis with safety. The P(a-et)CO2 gradient decreased from 46.4 mmHg to 11.8 mmHg (normal < 5 mmHg) and the end-tidal alveolar dead space fraction decreased from 0.85 to 0.37 (normal < 0.15) from the pre-thrombolysis period to the 7th day post-thrombolysis. We conclude that the volumetric capnography (VC) was useful in the patients diagnosis and clinical follow-up.This is the first report of a patient submitted to chemical thrombolysis due to massive pulmonary embolism (PE) during the postoperative period of neurosurgery, in whom due to the lack of adequate clinical conditions, no imaging assessment was performed. Clinical, gasometric and capnographic data allowed the decision to perform the thrombolysis with safety. The P(a-et)CO2 gradient decreased from 46.4 mmHg to 11.8 mmHg (normal < 5 mmHg) and the end-tidal alveolar dead space fraction decreased from 0.85 to 0.37 (normal < 0.15) from the pre-thrombolysis period to the 7th day post-thrombolysis. We conclude that the volumetric capnography (VC) was useful in the patients diagnosis and clinical follow-up.

Capnografia volumétrica como auxílio diagnóstico não-invasivo no tromboembolismo pulmonar agudo

Pulmonary thromboembolism is a common condition. Its diagnosis usually requires pulmonary scintigraphy, computed angiotomography, pulmonary arteriography and, in order to rule out other diagnoses, the measurement of D-dimer levels. Due to the fact that these diagnostic methods are not available in most Brazilian hospitals, the validation of other diagnostic techniques is of fundamental importance. We describe a case of a woman with chronic pulmonary hypertension who experienced a pulmonary thromboembolism event. Pulmonary scintigraphy, computed angiotomography and pulmonary arteriography were used in the diagnosis. The D-dimer test result was positive. Volumetric capnography was performed at admission and after treatment. The values obtained were compared with the imaging test results.

Capnografia volumétrica como meio de detectar obstrução pulmonar periférica precoce em pacientes com fibrose cística

OBJECTIVE: To compare spirometry and volumetric capnography (VCap) to determine if the capnographic values add more information about early lung disease in cystic fibrosis (CF) patients. METHODS: This was a cross-sectional study involving CF patients: Group I (42 patients, 6-12 years of age); and Group II (22 patients, 13-20 years of age). The corresponding control groups were comprised of 30 and 50 healthy subjects, respectively. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and the FEV1/FVC ratio was determined by spirometry. Using VCap, we measured peripheral oxygen saturation (SpO2), respiratory rate (RR), inspiratory time (IT), expiratory time (ET), and the phase III slope normalized by expiratory volume (phase III slope/Ve). RESULTS: In comparison with control groups, all CF patients presented higher phase III slope/Ve values (p < 0.001) independent of the pulmonary disease stage. The phase III slope/Ve was significantly higher in the 24 patients who presented normal spirometry results (p = 0.018). The Group II patients showed lower FVC, FEV1, FEV1/FVC (p < 0.05), and also lower SpO2 values (p < 0.001) when compared with Group I patients. In comparison with Control Group II, the Group II patients presented higher RR (p < 0.001), and lower IT and ET values (p < 0.001). CONCLUSIONS: Compared to the controls, all studied CF patients showed an increase in phase III slope/Ve values. VCap identified the heterogeneity of the ventilation distribution in the peripheral airways of CF patients who presented normal spirometry.

Mechanisms underlying gas exchange alterations in an experimental model of pulmonary embolism

The aim of the present study was to determine the ventilation/perfusion ratio that contributes to hypoxemia in pulmonary embolism by analyzing blood gases and volumetric capnography in a model of experimental acute pulmonary embolism. Pulmonary embolization with autologous blood clots was induced in seven pigs weighing 24.00 +/- 0.6 kg, anesthetized and mechanically ventilated. Significant changes occurred from baseline to 20 min after embolization, such as reduction in oxygen partial pressures in arterial blood (from 87.71 +/- 8.64 to 39.14 +/- 6.77 mmHg) and alveolar air (from 92.97 +/- 2.14 to 63.91 +/- 8.27 mmHg). The effective alveolar ventilation exhibited a significant reduction (from 199.62 +/- 42.01 to 84.34 +/- 44.13) consistent with the fall in alveolar gas volume that effectively participated in gas exchange. The relation between the alveolar ventilation that effectively participated in gas exchange and cardiac output (V Aeff/Q ratio) also presented a significant reduction after embolization (from 0.96 +/- 0.34 to 0.33 +/- 0.17 fraction). The carbon dioxide partial pressure increased significantly in arterial blood (from 37.51 +/- 1.71 to 60.76 +/- 6.62 mmHg), but decreased significantly in exhaled air at the end of the respiratory cycle (from 35.57 +/- 1.22 to 23.15 +/- 8.24 mmHg). Exhaled air at the end of the respiratory cycle returned to baseline values 40 min after embolism. The arterial to alveolar carbon dioxide gradient increased significantly (from 1.94 +/- 1.36 to 37.61 +/- 12.79 mmHg), as also did the calculated alveolar (from 56.38 +/- 22.47 to 178.09 +/- 37.46 mL) and physiological (from 0.37 +/- 0.05 to 0.75 +/- 0.10 fraction) dead spaces. Based on our data, we conclude that the severe arterial hypoxemia observed in this experimental model may be attributed to the reduction of the V Aeff/Q ratio. We were also able to demonstrate that V Aeff/Q progressively improves after embolization, a fact attributed to the alveolar ventilation redistribution induced by hypocapnic bronchoconstriction.

COPD phenotypes on computed tomography and its correlation with selected lung function variables in severe patients.

Background Computed tomography (CT) phenotypic characterization helps in understanding the clinical diversity of chronic obstructive pulmonary disease (COPD) patients, but its clinical relevance and its relationship with functional features are not clarified. Volumetric capnography (VC) uses the principle of gas washout and analyzes the pattern of CO2 elimination as a function of expired volume. The main variables analyzed were end-tidal concentration of carbon dioxide (ETCO2), Slope of phase 2 (Slp2), and Slope of phase 3 (Slp3) of capnogram, the curve which represents the total amount of CO2 eliminated by the lungs during each breath. Objective To investigate, in a group of patients with severe COPD, if the phenotypic analysis by CT could identify different subsets of patients, and if there was an association of CT findings and functional variables. Subjects and methods Sixty-five patients with COPD Gold III–IV were admitted for clinical evaluation, high-resolution CT, and functional evaluation (spirometry, 6-minute walk test [6MWT], and VC). The presence and profusion of tomography findings were evaluated, and later, the patients were identified as having emphysema (EMP) or airway disease (AWD) phenotype. EMP and AWD groups were compared; tomography findings scores were evaluated versus spirometric, 6MWT, and VC variables. Results Bronchiectasis was found in 33.8% and peribronchial thickening in 69.2% of the 65 patients. Structural findings of airways had no significant correlation with spirometric variables. Air trapping and EMP were strongly correlated with VC variables, but in opposite directions. There was some overlap between the EMP and AWD groups, but EMP patients had signicantly lower body mass index, worse obstruction, and shorter walked distance on 6MWT. Concerning VC, EMP patients had signicantly lower ETCO2, Slp2 and Slp3. Increases in Slp3 characterize heterogeneous involvement of the distal air spaces, as in AWD. Conclusion Visual assessment and phenotyping of CT in COPD patients is feasible and may help identify functional and clinically different subsets of patients. VC may provide useful information about the heterogeneous involvement of lung structures in COPD.

Atraumatic endotracheal tube for mechanical ventilation

BACKGROUND AND OBJECTIVES Patients who need to stay under endotracheal intubation for long periods or when undergoing general anesthesia may develop tracheal lumen injuries due to pressure from distal cuff. In some cases, these injuries may evolve to stenosis or, occasionally, necrosis. The objective of this study was to present a modified endotracheal tube (METT) in which the cuff pressure is variable according to the cycle of mechanical ventilation (MV), which was tested on a lung simulator and animal model. METHODS Two models of endotracheal tubes, a modified (METT) and a conventional (CETT), number 7.5 mm and 8.0 mm, were connected to a lung simulator in a mechanical ventilator adjusted with two tidal volumes (TV) of 10 and 15 mL.kg(-1) and a compliance of 60 mL.cmH(2)O to evaluate the ventilatory efficiency of METT. Both models were also compared in Large-White pigs under general anesthesia and MV for 48 consecutive hours. Subsequently, animals were sacrificed for histopathological analysis of their tracheas. RESULTS Both METTs (#7.5 and 8.0) presented air leaks in lung simulator. The smallest air leak (13%) was observed in METT #7.5 with TV = 15 mL.kg(-1), while the largest air leak (32%) was observed in METT #8.0 with TV = 10 mL.kg(-1). Nevertheless, both METTs showed good efficiency on the lung simulator. In animals, on histopathological analysis of their tracheas, it was found that METT caused less trauma to the epithelium when compared to CETT. CONCLUSION The use of a new model of ETT may decrease the risks of tracheal injury without hindering respiratory mechanics.

Volumetric capnography: in the diagnostic work-up of chronic thromboembolic disease.

The morbidity and mortality of pulmonary embolism (PE) have been found to be related to early diagnosis and appropriate treatment. The examinations used to diagnose PE are expensive and not always easily accessible. These options include noninvasive examinations, such as clinical pretests, ELISA D-dimer (DD) tests, and volumetric capnography (VCap). We report the case of a patient whose diagnosis of PE was made via pulmonary arteriography. The clinical pretest revealed a moderate probability of the patient having PE, and the DD result was negative; however, the VCap associated with arterial blood gases result was positive. The patient underwent all noninvasive exams following admission to hospital and again eight months after discharge. Results gained from invasive tests were similar to those produced by image exams, highlighting the importance of VCap as an important noninvasive tool.

Variáveis capnográficas pré e pós-tromboendarterectomias pulmonares

In these case report, the results of late dead space fraction (fDlate), end-tidal alveolar dead space fraction (AVDSf), arterial-alveolar gradient CO2 [P(a-et)CO2], and slope phase 3 of spirogram of two patients who underwent thromboendarterectomy for pulmonary embolism (PE) are shown. PE was diagnosed by pulmonary scintigraphy, helical tomography, and pulmonary angiography. The calculation of fDlate, AVDSf and P(a-et)CO2 was based on volumetric capnography associated with arterial blood gas analysis. The pre-operative fDlate of the first patient was 0.16 (cutoff 0.12) and AVDSf was 0.30 (cutoff 0.15). However, the fDlate of the second patient was false-negative (0.01) but, the AVDSf was positive (0.28). Postoperative fDlate of the first patient was -0.04 and AVDSf was 0.16; for the second patient, the values were 0.07 and 0.28, respectively. The association of these capnographic variables with image exams reinforces the importance of this noninvasive diagnosis method.