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Postoperative Impedance Testing Unreliable in Detecting Nissen Fundoplication Failure
Brittany N. Arnold*, Trudie a. Goers, Christy M. Dunst, Lee L. Swanstrom
Minimally Invasive Surgery, The Oregon Clinic, Portland, OR
Background: Objective confirmation of successful antireflux surgery currently relies on the gold standard 24-hour pH testing. Multichannel intraluminal impedance and pH monitoring (MII-pH) can provide more information and is being increasingly used in the postoperative setting. Based on available values for impedance testing, we have observed an abnormally high number of isolated impedance events in otherwise successful Nissen fundoplications. This study investigates the clinical validity of these impedance events, possible causes, and the utility of MII-pH in the setting of normal pH following Nissen fundoplication.Methods: All patients who had normal post-Nissen 24-hour pH using MII-pH (Sierra Scientific Instruments) were retrospectively reviewed from a prospectively collected database. Patient demographics, concurrent paraesophageal hiatal hernia (PEH) repair, postoperative symptomatology, manometry and MII-pH were reviewed. Patients who had esophageal lengthening procedures or other esophagogastric surgery were excluded. Normal values: pH <4.0, DeMeester score <14.76, impedance ≤73 events. Groups were compared using an unpaired t-test in SPSS.Results:Tables 1 & 2.Conclusion: Up to 50% of patients who have successful Nissen fundoplications may display abnormal impedance. Nissen patients who also undergo PEH repair are more likely to have abnormal impedance, and lower bolus and DEC pressures, than patients who have a Nissen alone. This may be due to anatomic changes that occur during the hernia reduction and repair causing fluid trapping in the distal esophagus. Therefore, MII-pH is not a reliable measure to document Nissen failure.
Normal vs. Abnormal patients (n=68)
| Age(years) | Sex | BMI | Surgeon | Concurrent PEH repair(# of patients) | Peristalsis Complete(%) | Residual P(mmHg) | Resting P(mmHg) | Bolus P(mmHg) | DEC Amplitude(mmHg) | Acid impedance events(#) | Weak acid impedance events(#) | Non acid impedance events(#) | |
| Normaln=33 | 53.1±14.5 | M: 13 (37%)F: 26 (63%) | 28.6±5.5 | A: 16 (46%)B: 19 (54%) | 7 (21%) | 87.4±14.0 | 13.2±7.1 | 18.4±13.7 | 38.0±14.0 | 38.0±14.0 | 1.7±4.1 | 26.4±18.1 | 5.4±8.5 |
| Abnormaln=35 | 58.8±12.4 | M: 9 (27%)F: 24 (73%) | 31.0±5.1 | A: 16(48%)B: 17 (52%) | 16 (48%) | 83.8±20.9 | 13.8± 6.0 | 17.4±11.1 | 30.4±7.7 | 30.4±7.7 | 4.8±9.4 | 130.9±72.8 | 22.9±25.4 |
| P value | 0.090 | 0.392 | 0.069 | 0.822 | 0.013 | 0.435 | 0.718 | 0.734 | 0.042 | 0.004 | 0.093 | 0.000 | 0.001 |
Nissen Fundoplication with and without PEH repair (n=68)
| # of patients with abnormal post-op impedance | Bolus P(mmHg) | DEC amplitude(mmHg) | Total impedance events(#) | Acid impedance events(#) | Weak acid impedance events(#) | Non acid impedance events(#) | |
| PEH(n=22) | 15 (68%) | 28.1±9.1 | 70.7±25.8 | 112.9±71.6 | 3.0±5.6 | 90.7±71.1 | 17.4±20.1 |
| Nissen alone(n=44) | 16 (36.4%) | 36.8±12.1 | 97.6±51.8 | 81.3±83.0 | 3.4±9.8 | 68.3±74.6 | 11.6±20.4 |
| P value | 0.014 | 0.022 | 0.007 | 0.112 | 0.861 | 0.237 | 0.268 |
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