Avaliação do diafragma por meio da ultrassonografia e sua associação com testes de função pulmonar em pacientes com anemia falciforme

Abstract

Sickle cell anemia (SCA) is an autosomal recessive hereditary haemolytic anemia, in which normal adult hemoglobin (Hb) is structurally altered, giving to the red blood cell an "sickled" shape when in hypoxic medium. It has a wide spectrum of clinical manifestations that determine great morbidity and mortality. In adults, the main concern is the chronic injuries of organs and systems, and the pulmonary and renal intercurrences are among the major causes of mortality and previous studies have observed restrictive ventilatory disorder and involvement of the respiratory muscles of these patients. The aim of the present study was to evaluate the morphological and functional aspects of the diaphragm by ultrasonography (USG) and to correlate it with the pulmonary function tests (PFT) of adult patients with SCA. This is a cross-sectional observational study with 40 adult patients with SCA, both genders, followed at the Hematology outpatient clinic of the Hospital Universitário Pedro Ernesto (HUPE), who underwent USG of the diaphragm and PFT, with a one month interval between each other. A group of 44 volunteers with normal body mass index (BMI), non-smokers and without respiratory complaint of any kind, where also recruited to perform only the USG of the diaphragm. All evaluated diaphragms had preserved echogenicity (hypoechoic) and their thickness showed no statistical difference between the groups. However, the SCA group had significantly higher right hemidiaphragm mobility at deep inspiration (p = 0.004) and sniff test (p = 0.0008), and lower left hemidiaphragm mobility during basal respiration (p = 0.009). Multiple linear regression showed that right hemidiaphragm thickness in expiratory apnea (p = 0.004; p = 0.007) and right hemidiaphragm mobility in deep breathing (p = 0.022; p = 0.032) were significant independent variables to explain both total lung volume (TLC, L / btps) and forced vital capacity (FVC, L / btps), these being the strongest correlations. There was a predominance of restrictive ventilatory disorder (65%) and overall reduction in respiratory muscle strength, and 17.5% had an isolated reduction of expiratory force. The results obtained at USG show preservation of the morphostructural aspects, as well as the absence of weakness or muscular dysfunction of the diaphragm in patients with SCA. They also suggest that US can be a possible predictor of pulmonary function and thus can be used as an auxiliary tool in the segment of patients with SCA, especially in those with difficulties in performing PFTs.