Haemodynamic Parameters Obtained by Transthoracic Echocardiography and Swan-Ganz Catheter: a Comparative Study in Liver Transplant Patients

Objectivo: estudo comparativo simultâneo de medições invasivas utilizando o cateterismo da artéria pulmonar e não invasivas utilizando a ecocardiografia transtorácica (ETT) de 4 parâmetros hemodinâmicos: débito cardíaco (DC), pressão de encravamento da artéria pulmonar (PCP), pressão venosa central (PVC), e pressão sistólica da artéria pulmonar (PSAP). Material e Métodos: estudo prospectivo numa Unidade de Cuidados Intensivos (UCI) médico-cirurgica. Foram estudados 41 doentes em pós-operatório de transplante hepático, nos quais o DC, a PCP, a PVC e a PSAP foram obtidos em simultâneo por 2 observadores independentes, utilizando a ETT e o cateterismo invasivo da artéria pulmonar. Para a quantificação por ETT dos parâmetros foram utilizadas fórmulas descritas na literatura. As medições invasivas e não invasivas foram comparadas através de uma análise de correlação linear e de Bland-Altman. Resultados: Verificou-se uma boa correlação nas medições invasivas e não invasivas do DC (r=0,97) e PVC (r=0,88). As correlações entre as medições invasivas e não invasivas da PCP e da PSAP foram fracas (r=0,41 e r= 0,118 respectivamente). O intervalo de confiança de 95% e bias para o DC foi negligenciável, em especial para valores de DC abaixo dos 6l/minuto. A ETT subestima em regra o DC, mas as duas técnicas mostraram uma correlação significativa entre si. Conclusões: a ETT pode estimar de forma fidedigna o DC em doentes submetidos a transplante hepático. A determinação não invasiva das restantes variáveis hemodinâmicas por ETT pode estar sujeita a uma variabilidade grande relacionada com as características dos doentes. Apesar dos dados terem sido obtidos num grupo específico de doentes, podem ajudar a definir uma aplicação futura da ecocardiografia em Cuidados Intensivos.

Optimization of fMRI Processing Parameters for Simutaneous Acquisition of EEG/fMRI in Focal Epilepsy

In the context of focal epilepsy, the simultaneous combination of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) holds a great promise as a technique by which the hemodynamic correlates of interictal spikes detected on scalp EEG can be identified. The fact that traditional EEG recordings have not been able to overcome the difficulty in correlating the ictal clinical symptoms to the onset in particular areas of the lobes, brings the need of mapping with more precision the epileptogenic cortical regions. On the other hand, fMRI suggested localizations more consistent with the ictal clinical manifestations detected. This study was developed in order to improve the knowledge about the way parameters involved in the physical and mathematical data, produced by the EEG/fMRI technique processing, would influence the final results. The evaluation of the accuracy was made by comparing the BOLD results with: the high resolution EEG maps; the malformative lesions detected in the T1 weighted MR images; and the anatomical localizations of the diagnosed symptomatology of each studied patient. The optimization of the set of parameters used, will provide an important contribution to the diagnosis of epileptogenic focuses, in patients included on an epilepsy surgery evaluation program. The results obtained allowed us to conclude that: by associating the BOLD effect with interictal spikes, the epileptogenic areas are mapped to localizations different from those obtained by the EEG maps representing the electrical potential distribution across the scalp (EEG); there is an important and solid bond between the variation of particular parameters (manipulated during the fMRI data processing) and the optimization of the final results, from which smoothing, deleted volumes, HRF (used to convolve with the activation design), and the shape of the Gamma function can be certainly emphasized.

Ocular Pulse Amplitude and Doppler Waveform Analysis in Glaucoma Patients

PURPOSE: To determine the correlation between ocular blood flow velocities and ocular pulse amplitude (OPA) in glaucoma patients using colour Doppler imaging (CDI) waveform analysis. METHOD: A prospective, observer-masked, case-control study was performed. OPA and blood flow variables from central retinal artery and vein (CRA, CRV), nasal and temporal short posterior ciliary arteries (NPCA, TPCA) and ophthalmic artery (OA) were obtained through dynamic contour tonometry and CDI, respectively. Univariate and multiple regression analyses were performed to explore the correlations between OPA and retrobulbar CDI waveform and systemic cardiovascular parameters (blood pressure, blood pressure amplitude, mean ocular perfusion pressure and peripheral pulse). RESULTS: One hundred and ninety-two patients were included [healthy controls: 55; primary open-angle glaucoma (POAG): 74; normal-tension glaucoma (NTG): 63]. OPA was statistically different between groups (Healthy: 3.17 ± 1.2 mmHg; NTG: 2.58 ± 1.2 mmHg; POAG: 2.60 ± 1.1 mmHg; p < 0.01), but not between the glaucoma groups (p = 0.60). Multiple regression models to explain OPA variance were made for each cohort (healthy: p < 0.001, r = 0.605; NTG: p = 0.003, r = 0.372; POAG: p < 0.001, r = 0.412). OPA was independently associated with retrobulbar CDI parameters in the healthy subjects and POAG patients (healthy CRV resistance index: β = 3.37, CI: 0.16-6.59; healthy NPCA mean systolic/diastolic velocity ratio: β = 1.34, CI: 0.52-2.15; POAG TPCA mean systolic velocity: β = 0.14, CI 0.05-0.23). OPA in the NTG group was associated with diastolic blood pressure and pulse rate (β = -0.04, CI: -0.06 to -0.01; β = -0.04, CI: -0.06 to -0.001, respectively). CONCLUSIONS: Vascular-related models provide a better explanation to OPA variance in healthy individuals than in glaucoma patients. The variables that influence OPA seem to be different in healthy, POAG and NTG patients.