Role of the Diaphragm in GERD and LPR
The crural diaphragm is a critical component of the anti-reflux barrier, contributing approximately 50% of the barrier's competence alongside the lower esophageal sphincter, and diaphragmatic breathing exercises should be incorporated as adjunctive therapy for patients with GERD. 1, 2
Anatomical and Physiological Function
The crural diaphragm (CD) functions as an active, dynamic component of the gastroesophageal junction rather than a passive anatomical structure 1:
- The CD actively relaxes when the distal esophagus is distended and contracts when the stomach is distended, providing a responsive mechanical barrier against reflux 1
- Computer models integrating physiological data demonstrate that the CD and lower esophageal sphincter each contribute roughly 50% to the overall GERD barrier competence 1
- While the diaphragm plays minimal role in cardial competence at rest, diaphragmatic contraction becomes essential during conditions of increased intra-abdominal pressure such as physical activity, abdominal straining, or postprandial states 3
Evidence for Diaphragmatic Dysfunction in GERD
Multiple lines of evidence establish the CD's critical role in reflux pathophysiology 1:
- Crural myotomy in animal models directly increases esophageal acid exposure, confirming the CD's protective function 1
- Physiological studies in patients with symptomatic hiatal hernia demonstrate that CD dysfunction is directly associated with GERD development 1
- Patients with non-reducing hiatal hernia experience prolonged acid clearance times, partly attributable to compromised diaphragmatic function 3
Therapeutic Application: Diaphragmatic Breathing
The 2022 AGA guidelines recommend referral to behavioral therapists for diaphragmatic breathing exercises in patients with functional heartburn or reflux disease associated with esophageal hypervigilance or reflux hypersensitivity 4:
Mechanism of Action
- During the inspiratory portion of diaphragmatic breathing, lower esophageal sphincter pressure increases significantly (42.2 vs 23.1 mm Hg, P < 0.001) in both GERD patients and healthy controls 2
- Diaphragmatic breathing reduces postprandial reflux events by increasing the pressure gradient between the LES and gastric pressure 2
Clinical Efficacy
- Postprandial diaphragmatic breathing reduces the number of reflux events from 2.60 to 0.36 (P < 0.001) in GERD patients 2
- In a 2-hour window after standardized meals, esophageal acid exposure decreased from 11.8% ± 6.4 to 5.2% ± 5.1 (P = 0.015) with diaphragmatic breathing 2
- During 48-hour ambulatory monitoring, diaphragmatic breathing significantly reduced reflux episodes compared to observation (P = 0.049) 2
Patient Education Strategy
Educating patients about the crural diaphragm's role facilitates adherence to diaphragmatic breathing exercises 4:
- Explain that the diaphragm acts as a physical valve that can be strengthened through breathing exercises, similar to strengthening any other muscle 4
- Emphasize that understanding the intra-abdominal to intra-thoracic pressure gradient improves acceptance of weight management and modified dietary/nighttime routines 4
- Provide standardized educational material on GERD mechanisms, including the protective role of the anti-reflux barrier and crural diaphragm 4
Surgical Implications
Effective GERD management mandates repair of the crural diaphragm and reinforcement of the lower esophageal sphincter 1:
- Magnetic sphincter augmentation is often combined with crural repair in the setting of known hiatal hernia 4
- Given high rates of hiatal hernia recurrence, novel antireflux procedures should target crural integrity as an essential component 1
- Laparoscopic fundoplication procedures inherently address both the LES and crural components of the anti-reflux barrier 4
Clinical Pitfalls
Do not overlook the diaphragmatic component when evaluating treatment failure 1:
- Patients with large hiatal hernias have compromised crural function and may require surgical intervention rather than escalating medical therapy alone 4, 1
- Behavioral interventions targeting diaphragmatic breathing should be initiated early rather than reserved for refractory cases 4, 2
- Treatments administered by clinical health psychologists or mental health professionals with specialized training in chronic GI disorders achieve optimal results 4