Original Research: Acute chest syndrome in sickle cell disease: Effect of genotype and asthma

Benefit of pulmonary subspecialty care for children with sickle cell disease and asthma

OBJECTIVE

Asthma is a recognized comorbidity in children with sickle cell disease (SCD). It increases the risk of acute chest syndrome (ACS), vaso-occlusive episodes, and early mortality. We aim to determine whether evaluation and management of children with SCD and asthma by a pulmonologist reduce rate of asthma exacerbation and ACS.

METHODS

The study included 192 patients with SCD (0-21 years) followed at Children's Hospital of Philadelphia Hematology between January 1, 2015, and December 31, 2018, with a diagnosis of asthma, wheeze, or cough. Patients were placed in two groups: those evaluated by a pulmonologist (SCD-A-P) and those not (SCD-A). Rates of emergency department (ED) visits and hospitalizations for asthma exacerbation and ACS were compared between groups and over time.

RESULTS

SCD-A-P patients (n = 70) were predominantly SCD type SS with lower hemoglobin and hematocrit compared to SCD-A patients (n = 122). SCD-A-P started with a higher average rate of hospital visits for asthma exacerbation and ACS per year (2.69 [1.02-4.37]) compared to SCD-A (0.43 [0.24-0.63]), (p < 0.001). For SCD-A-P patients with at least one hospital visit (n = 48), the average rate decreased from 3.93 (1.57-6.29) to 0.85 (0.48-1.23) following pulmonary consultation (p = 0.014) and was comparable to the SCD-A rate by study end.

CONCLUSION

SCD-A-P was mainly SCD type SS and had higher ED/hospitalization rates for asthma exacerbation and ACS compared to SCD-A, but the rates significantly decreased following pulmonology consultation. These findings support the pulmonologist's role in the multidisciplinary care of SCD patients and highlight the need for evidence-based asthma guidelines for children with SCD.

Asthma, allergic sensitization and lung function in sickle cell disease

BACKGROUND

Pulmonary disease is a frequent acute and chronic manifestation in sickle cell disease (SCD), presenting high morbidity and mortality.

OBJECTIVES

To identify the prevalence and association of asthma, allergic sensitization and altered pulmonary function in patients with SCD (SS and Sβ^o).

METHODS

A single-center, cross-sectional study was conducted, in which 70 patients with SCD and 44 controls, aged six to 18 years, responded to the questionnaire of the International Study of Asthma and Allergies in Childhood (ISAAC), complemented with an anamnesis regarding the associated clinical outcomes. All patients underwent immediate hypersensitivity skin tests with aeroallergens and a pulmonary function evaluation (spirometry). Regarding the statistical analysis, parametric and non-parametric methods were used, depending on the variables studied. Tests were considered significant when p<0.05.

RESULTS

There was no significant difference between the patients and controls regarding the prevalence of asthma and allergic sensitization (p>0.05). The number of occurrences of acute chest syndrome per patient per year was significantly higher for asthmatic patients than for non-asthmatic patients (p=0.04). Obstructive pulmonary function occurred in 30.9% of the patients and in 5.4% of the controls, and restrictive pulmonary function occurred in 5.5% of the patients and 5.4% of the controls. Asthma and wheezing in the last 12months had significant associations with obstructive pulmonary function (p=0.014 and p=0.027, respectively).

CONCLUSIONS

The occurrence of asthma, allergic sensitization and alteration in lung function in patients with SCD reinforces the importance of routine monitoring of these diagnoses, which allows for early treatment and prevention of the evolution of pulmonary disease in adulthood.

Clinical and imaging profiles of pulmonary embolism: a single-institution experience

BACKGROUND

Pulmonary embolism (PE) is a common life-threatening condition with non-specific clinical presentations. The diagnosis of PE depends highly on imaging studies, which may also provide prognostic information. This study aimed to describe the clinical and imaging profiles of patients with PE, emphasizing the differences between central and peripheral PE.

METHODS

After ethics review board approval, this retrospective observational study examined the non-negative results in adult patients who underwent computed tomography pulmonary angiography (CT-PA) at our hospital between May 2016 and December 2019. Demographic and clinical information and imaging findings were collected from the electronic medical records.

RESULTS

The study included 85 cases that were identified after re-interpreting the 103 non-negative CT-PA scans. Six cases were excluded for incomplete data and 12 cases were false-positive. Central PE was found in 63.5% of the cases. Obesity was the most common risk factor seen in 37.6% of the cases. Furthermore, 9.4% of the patients had sickle cell disease, which tended to be associated with peripheral PE. There was no difference between the peripheral and central PE in most clinical and imaging parameters evaluated (P > 0.05). However, patients with isolated subsegmental PE were more likely to develop hemoptysis (P = 0.04).

CONCLUSION

This study suggests that patients with obesity and sickle cell disease constitute an important proportion of all PE cases. Furthermore, the clinical and imaging profiles in patients with peripheral PE are similar to those in patients with central PE. Future research should focus on the clinical value of peripheral PE in patients with sickle cell disease.

Shear dependent red blood cell adhesion in microscale flow

Non-adherence and deformability are the key intrinsic biomechanical features of the red blood cell (RBC), which allow it to tightly squeeze and pass through even the narrowest of microcirculatory networks. Blockage of microcirculatory flow, also known as vaso-occlusion, is a consequence of abnormal cellular adhesion to the vascular endothelium. In sickle cell disease (SCD), an inherited anaemia, even though RBCs have been shown to be heterogeneous in adhesiveness and deformability, this has not been studied in the context of physiologically relevant dynamic shear gradients at the microscale. We developed a microfluidic system that simulates physiologically relevant shear gradients of microcirculatory blood flow at a constant single volumetric flow rate. Using this system, shear dependent adhesion of RBCs from 28 subjects with SCD and from 11 healthy subjects was investigated using vascular endothelial protein functionalized microchannels. We defined a new term, RBC Shear Gradient Microfluidic Adhesion (SiGMA) index to assess shear dependent RBC adhesion in a subject-specific manner. We have shown for the first time that shear dependent adhesion of RBCs is heterogeneous in a microfluidic flow model, which correlates clinically with inflammatory markers and iron overload in subjects with SCD. This study reveals the complex dynamic interactions between RBC-mediated microcirculatory occlusion and clinical outcomes in SCD. These interactions may also be relevant to other microcirculatory disorders and microvascular diseases.