Selective dysfunction of the crural diaphragm in patients with chronic restrictive and obstructive lung disease.

BACKGROUND: Gastroesophageal reflux (GER) is known to be associated with chronic lung diseases. The driving force of GER is the transdiaphragmatic pressure (Pdi) generated mainly by costal and crural diaphragm contraction. The latter also enhances the esophagogastric junction (EGJ) pressure to guard against GER. METHODS: The relationship between Pdi and EGJ pressure was determined using high resolution esophageal manometry in patients with interstitial lung disease (ILD, n = 26), obstructive lung disease (OLD, n- = 24), and healthy subjects (n = 20). KEY RESULTS: The patient groups did not differ with respect to age, gender, BMI, and pulmonary rehabilitation history. Patients with ILD had significantly higher Pdi but lower EGJ pressures as compared to controls and OLD patients (p < 0.001). In control subjects, the increase in EGJ pressure at all-time points during inspiration was greater than Pdi. In contrast, the EGJ pressure during inspiration was less than Pdi in 14 patients with ILD and 7 patients with OLD. The drop in EGJ pressure was usually seen after the peak Pdi in ILD group (p < 0.0001) and before the peak Pdi in OLD group, (p = 0.08). Nine patients in the ILD group had sliding hiatus hernia, compared to none in control subjects (p = 0.003) and two patients in the OLD, (p = 0.04). CONCLUSIONS AND INFERENCES: A higher Pdi and low EGJ pressure, and dissociation between Pdi and EGJ pressure temporal relationship suggests selective dysfunction of the crural diaphragm in patients with chronic lung diseases and may explain the higher prevalence of GERD in ILD as seen in previous studies.

Variation in Sodium Intake and Intra-individual Change in Blood Pressure in Chronic Kidney Disease.

OBJECTIVE: In the kidney disease clinic setting, higher-than-usual blood pressure is often ascribed to recent dietary sodium indiscretion. While clinical trials demonstrate a clear relationship between salt intake and blood pressure on the population level, it is uncertain whether real-world variation in sodium intake within individual chronic kidney disease (CKD) patients is associated with fluctuations in blood pressure. METHODS: We analyzed data from the Phosphorus Normalization Trial, in which participants with CKD eating their usual diets completed at least three 24-hour urine collections over 9 months, from which we measured sodium. Blood pressure was measured at the time of 24-hour urine collections. For each individual participant, we assessed the slope of the relationship between sodium intake and mean arterial blood pressure (MAP). RESULTS: Among 119 participants (mean age 67 years and mean estimated glomerular filtration rate 31 mL/minute/1.73 m2), there was substantial variation in sodium intake as measured by 24-hour urine collections (mean intake 3,903 mg/day, standard deviation 1037 mg/day). Individual participants had highly variable associations between their sodium intake and their MAP; 47% (n = 56) had inverse associations between sodium and MAP, whereas the remainder had positive (salt-sensitive) associations. CONCLUSIONS: Among CKD patients, there is substantial variation in sodium intake but no predictable relationship between dietary sodium and blood pressure in individuals. The frequent dismissal of elevated blood pressure readings as related to recent sodium intake in clinic may be a misapplication of large-scale population data to explain individual variability and may contribute to clinical inertia regarding high blood pressure treatment.

3D/2D model-to-image registration applied to TIPS surgery.

We have developed a novel model-to-image registration technique which aligns a 3-dimensional model of vasculature with two semiorthogonal fluoroscopic projections. Our vascular registration method is used to intra-operatively initialize the alignment of a catheter and a preoperative vascular model in the context of image-guided TIPS (Transjugular, Intrahepatic, Portosystemic Shunt formation) surgery. Registration optimization is driven by the intensity information from the projection pairs at sample points along the centerlines of the model. Our algorithm shows speed, accuracy and consistency given clinical data.

Comparison of simultaneous and sequential two-view registration for 3D/2D registration of vascular images.

Accurate 3D/2D vessel registration is complicated by issues of image quality, occlusion, and other problems. This study performs a quantitative comparison of 3D/2D vessel registration in which vessels segmented from preoperative CT or MR are registered with biplane x-ray angiograms by either a) simultaneous two-view registration with advance calculation of the relative pose of the two views, or b) sequential registration with each view. We conclude on the basis of phantom studies that, even in the absence of image errors, simultaneous two-view registration is more accurate than sequential registration. In more complex settings, including clinical conditions, the relative accuracy of simultaneous two-view registration is even greater.