The Role of the Transdiaphragmatic Pressure Gradient (TGP) in the Pathophysiology of Proximal Reflux

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.

CIRURGIA LAPAROSCÓPICA ANTI-REFLUXO: PERGUNTAS ANTIGAS FORAM RESPONDIDAS ? É ÚTIL NOS SINTOMAS EXTRA-ESOFÁGICOS ?

Gastroesophageal reflux disease is usually associated with esophageal or typical symptoms such as heartburn, regurgitation, and dysphagia. However, there is today mounting evidence that gastroesophageal reflux can also cause extra-esophageal or atypical problems such as cough, aspiration pneumonia, and pulmonary fibrosis. AIM: The aim of this study was to discuss the pathophysiology of extra-esophageal symptoms, the diagnostic evaluation, complications, and the outcome of video laparoscopic antireflux surgery.