Gastroesophageal reflux disease and pulmonary function: a potential role of the dead space extension

Influence of Achalasia on the Spirometry Flow-Volume Curve and Peak Expiratory Flow

BACKGROUND

Achalasia is an esophageal motor disorder characterized by aperistalsis and the failure of the relaxation of the lower esophageal sphincter. We want to find out whether external compression or recurrent micro-aspiration of undigested food has a functional effect on the airway.

METHODS

The aim of this research was to analyze the influence of achalasia on the peak expiratory flow and flow-volume curve. All of the 110 patients performed spirometry.

RESULTS

The mean diameter of the esophagus was 5.4 ± 2.1 cm, and nine of the patients had mega-esophagus. Seven patients had a plateau in the inspiratory part of the flow-volume curve, which coincides with the patients who had mega-esophagus. The rest of the patients had a plateau in the expiration part of the curve. The existence of a plateau in the diameter of the esophagus of more than 5 cm was significant (p 0.003). Statistical significance between the existence of a plateau and a lowered PEF (PEF < 80) has been proven (p 0.001). Also, a statistical significance between the subtype and diameter of more than 4 cm has been proved. There was no significant improvement in the PEF values after operation. In total, 20.9% of patients had a spirometry abnormality finding. The frequency of the improvement in the spirometry values after surgery did not differ significantly by achalasia subtype. The improvement in FEV1 was statistically significant compared to the FVC values.

CONCLUSIONS

Awareness of the influence of achalasia on the pulmonary parameters is important because low values of PEF with a plateau on the spirometry loop can lead to misdiagnosis. The recognition of various patterns of the spirometry loop may help in identifying airway obstruction caused by another non-pulmonary disease such as achalasia.

Preparation and evaluation of sustained release pirfenidone-loaded microsphere dry powder inhalation for treatment of idiopathic pulmonary fibrosis

Pirfenidone (PFND) is a recommended oral drug used to treat idiopathic pulmonary fibrosis, but have low bioavailability and high hepatotoxicity. The study, therefore, seeks to improve the therapeutic activities of the drug via increased bioavailability and reduced associated side effects by developing a novel drug delivery system. The electrostatic spray technology was used to prepare a sustained release pirfenidone-loaded microsphere dry powder inhalation with PEG-modified chitosan (PFND-mPEG-CS-MS). The entrapment efficiency, drug loading, and in vitro cumulative drug release rate (at 24 h and with a sustained release effect) of PFND-mPEG-CS-MS were 77.35±3.01%, 11.45±0.64%, and 90.4%, respectively. The Carr's index of PFND-mPEG-CS-MS powder was 17.074±2.163% with a theoretical mass median aerodynamic diameter (MMADt) of 0.99±0.07 μm, and a moisture absorption weight gain rate (Rw) of 4.61±0.72%. The emptying rate, pulmonary deposition rate (fine particle fraction) and actual mass median aerodynamic diameter (MMADa) were 90%∼95%, 48.72±7.04% and 3.10±0.16 μm, respectively. MTT bioassay showed that mPEG-CS-MS (200 μg/mL) had good biocompatibility (RGR = 90.25%) and PFND-mPEG-CS-MS (200 μg/mL) had significant inhibitory activity (RGR = 49.82%) on fibroblast growth. The pharmacokinetic data revealed that the t1/2 (5.02 h) and MRT (10.66 h) of PFND-mPEG-CS-MS were prolonged compared with the free PFND (t1/2, 1.67 h; MRT, 2.71 h). The pharmacodynamic results also showed that the formulated-drug group had slight pathological changes, lower lung hydroxyproline content, and reduced hepatotoxicity compared with the free-drug group. The PFND-mPEG-CS-MS further significantly down-regulated TGF-β cytokines, Collagen I, and α-SMA protein expression levels compared with the free drug. The findings indicated that the PFND-mPEG-CS-MS had a good sustained release effect, enhanced bioavailability, decreased toxicity, and increased anti-fibrotic activities.

Lung function parameters in patients with gastroesophageal reflux without respiratory symptoms: a case-control study

AIM

This research aimed to evaluate the effect of gastroesophageal reflux disease (GERD) on pulmonary volumes, airflows, and airway resistance in the patients without respiratory symptoms and compare them with the healthy subjects.

BACKGROUND

GERD is the return of gastric content into the esophagus and beyond. GERD may play an essential role in the extraesophageal diseases, including chest pain, asthma, laryngitis, chronic cough, and sinusitis. The relation between GERD and airway involvement in asthma and also bronchoconstrictor effects of GERD are well recognized, but its impact on lung parameters in the patients with GERD without respiratory symptoms is unclear.

METHODS

In a case-control study, 78 GERD patients without pulmonary symptoms and 93 healthy subjects as control group were enrolled. The impulse oscillometry examined airway resistance. The body plethysmograph measured the pulmonary volumes and airflows.

RESULTS

The mean age of GERD patients and the healthy subjects were 37.30±9.76 and 34.74±11.10, respectively. A total of 53.8% of patients and 67.7% of healthy subjects were male. The lung volumes measured by the body plethysmography were normal in both patients and healthy subjects. However, there was a significant difference between the groups in forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) (P=0.01) and maximal mid expiratory flow (MMEF) (P=0.008). Airway resistance at R5Hz was significantly higher in the case group than the control group (P=0.001).

CONCLUSION

The results of the current study demonstrated that GERD patients have small airway disease even in the absence of respiratory symptoms.

The prevalence of gastro-esophageal reflux disease and esophageal dysmotility in Chinese patients with idiopathic pulmonary fibrosis

Background

The cause of idiopathic pulmonary fibrosis (IPF) remains unknown, yet gastro-esophageal reflux disease (GERD) is highly prevalent in this population. GERD prevalence was studied, and esophageal function tests (EFT) were assessed in Chinese IPF patients.

Methods

We prospectively studied 69 IPF patients who undertook both stationary High Resolution esophageal Manometry/Impedance (HRiM) and 24-hour esophageal Multi-Channel Intraluminal Impedance with pH Recordings (MII/pH). Patients were divided into GERD+ and GERD- groups according to pH results. Controls were HRiM treated healthy volunteers, and patients without IPF received HRiM and MII/pH diagnosed with GERD.

Results

69 IPF patients, 62 healthy volunteers, and 88 IPF negative GERD patients were selected. GERD prevalence in IPF was 43/69 (62.3%), and 58.1% of patients presented with at least one typical symptom. Symptoms had a sensitivity of 58.1%, a specificity of 61.6%, a positive predictive value of 71.4% and a negative predictive of 47.1%. Compared with healthy volunteers, IPF patients had significantly decreased lower esophageal sphincter pressure (LESP), upper esophageal sphincter pressure (UESP) and complete bolus transit rate (CBTR). By contrast, IPF patients had increased total bolus transit time and prevalence of weak peristalsis. MII/pH showed that one third of IPF patients had abnormal distal and proximal reflux, especially non-acid reflux. Compared with GERD patients without IPF, GERD patients with IPF had significantly decreased CBTR and UESP with increased bolus exposure time.

Conclusions

GERD prevalence in IPF was high, but symptoms alone were an unreliable predictor of reflux. IPF patients had lower LESP and UESP, impaired esophageal peristalsis and bolus clearance function with more proximal reflux events.

Lung diffusion capacity in children with respiratory symptoms and untreated GERD

BACKGROUND

Gastroesophageal reflux disease (GERD) is associated with many respiratory disorders, among which, chronic cough, laryngitis, and asthma are among the most common. We investigated lung function, including gas diffusion capacity, in children with poor asthma control or chronic laryngitis with untreated GERD.

MATERIAL AND METHODS

A total of 71 children, aged 6-17 years, with chronic respiratory and other symptoms suggestive for GERD, were enrolled and divided into 2 groups: chronic laryngitis and asthma. Participants underwent 24-hour pH monitoring and lung function assessment, measurement of single-breath diffusing capacity of the lung for carbon monoxide (DLCO), and fraction of exhaled nitric oxide (FENO) measurement.

RESULTS

24-hour pH monitoring was positive for GERD in 92.1% of preselected children with asthma and 90.1% of children with chronic recurrent laryngitis. All flows (PEF, MEF75, MEF50, and MEF25) were significantly lower in the asthma group, while FENO and DLCO were significantly lower in the laryngitis group. A significant inverse relationship was found between DLCO and all reflux indexes in the laryngitis group. Each unit change of Johnson-DeMeester score and Boix-Ochoa score increased the odds for significantly lower DLCO in laryngitis patients by 3.9% and 5.5%, respectively.

CONCLUSIONS

In children with uncontrolled asthma and chronic laryngitis, the regurgitation of gastric contents due to GERD contributes to poor asthma control and aggravation of chronic laryngitis. Despite having normal lung function, the gas diffusion capacity should be controlled in patients with GERD and chronic laryngitis, and it might be the very first abnormality in distal airways.

Bronchoalveolar pH and inflammatory biomarkers in newly diagnosed IPF and GERD patients: a case-control study

Background

Several studies have suggested that idiopathic pulmonary fibrosis (IPF) may be related to repeated aspiration of gastric contents over long periods of time. We aimed to investigate differences between pH measured directly in the lung, and biomarkers of acute inflammation in patients with newly diagnosed IPF and in patients with newly diagnosed GERD.

Material/Methods

All subjects (N=61) underwent collection of medical history, physical examination, pulmonary function testing, bronchoscopy, endoscopy, arterial blood gas analyses, and biochemical testing.

Results

Previously diagnosed GERD was found in 56.7%, typical symptoms of reflux in 80%, and Helicobacter pylori in gastric biopsy specimens in 76.6% of the cases. pH in peripheral branches of bronchi in the cases was 5.32±0.44 and was 6.27±0.31 (p<0.001) in the control group. The average values of LDH, ALP, and CRP in bronchoalveolar aspirate and in serum, as well as TNF-α in bronchoalveolar aspirate, were significantly higher in IPF patients.

Conclusions

The more acidic environment in the bronchoalveolar aspirate of the IPF subjects could contribute to the development or progression of IPF, possibly via changes in local metabolism or by damaging local cells and tissue. However, further studies with larger numbers of patients are required to clarify the role of gastric fluid aspiration in IPF pathogenesis. Our preliminary work has identified inflammatory biomarkers LDH, ALP, and TNF-α as potentially important in the pathologic processes in IPF. Further research is needed to determine their importance in clinical intervention and patient care.