Effect of nasal continuous positive airway pressure on esophageal function.

OBJECTIVE: The purpose of this study was to conduct a prospective investigation of the mechanism(s) of nasal continuous positive airway pressure (CPAP) upon the reduction of recumbent gastroesophageal reflux. DESIGN: Prospective assessment. SETTING: Health Sciences Center and St. Boniface General Hospital, Winnipeg, Manitoba. METHODS: An esophageal motility examination was conducted on 16 patients during the application of nasal CPAP set at 0 cm, 4 cm, and 8 cm water pressure. Esophageal parameters studied were wave amplitude and velocity, midesophageal resting pressure, and upper and lower esophageal sphincter resting pressure. RESULTS: The midesophageal resting pressure increased significantly from a baseline of -3.5 +/- 1.4 mm Hg to -1.6 +/- 1.8 mm Hg at 4 cm CPAP (p < .01) and -0.9 +/- 1.2 mm Hg at 8 cm CPAP (p < .01). CONCLUSIONS: The known reduction of nocturnal reflux that occurs when patients use an application of nasal CPAP appears to be related to direct mechanical compression of the esophagus. Results of an earlier report suggesting a reflex response by the lower sphincter were not reproduced.

Impact of ingested liquids on 24-hour ambulatory pH tests.

A prospective investigation of the impact of ingested liquids on 24-hr pH test scores was conducted. Eighty-two patients contributed 142 samples. The liquids used were coffee/tea (N = 35), water (N = 32), fruit juice (N = 29), cola (N = 34), and beer (N = 12). The pH of cola, juice, and beer are approximately 3.0. The parameters studied included: total test time, total drink time, total minutes of pH < 4.0 during drink, minutes of < pH 4.0 10 min before drink, and minutes of pH < 4.0 10 min following drink. Analysis was performed using one-way ANOVA and repeated measures. Age of patients, total test time, and total time pH < 4.0 were not significantly different (P > 0.05). The total time to consume the drink was significantly greater (P < 0.05) for beer than all other liquids. The total time (7.7 +/- 6.0 min) pH < 4.0 for cola was significantly different (P < 0.023) than beer (3.3 +/- 3.7 min), tea/coffee (1.4 +/- 6.5 min), and water (1.1 +/- 2.5 min). The percentage of total time pH < 4.0 was not significantly different (P > 0.05) among any of the liquids. The percentage of time pH < 4.0 during the drink was the highest for cola (63 +/- 47%) and juice (51 +/- 57%); water, coffee/tea, and beer were not significantly different (P > 0.05). Although the impact of cola and juice were the greatest, none of these had an impact that exceeded 0.5%. The lack of impact of beer appears to be due to the increased period of time it takes to consume. We conclude that the impact of ingested fluids is minimal and can probably be disregarded in most patient groups.

A prospective assessment of gastroesophageal reflux before and after treatment of achalasia patients: pneumatic dilation versus transthoracic limited myotomy.

OBJECTIVES: We conducted this study to determine whether reflux should be a major consideration in the choice of treatment for achalasia patients. Achalasia patients undergoing either pneumatic dilation or transthoracic limited esophagomyotomy were monitored for reflux before and after treatment, for comparison. METHODS: Twenty-four hour ambulatory esophageal pH tests and esophageal manometry were performed on 32 consecutive, untreated achalasia patients. Studied (before and after treatment) were 17 patients who underwent pneumatic dilation and 15 patients who received transthoracic limited myotomy without fundoplication. All follow-up studies were completed within 12 months of treatment. RESULTS: The ages of the two groups were not significantly different (p > 0.05, 45 +/- 9 yr myotomy vs. 44 +/- 13 yr dilation). The resting lower esophageal sphincter pressure was not significantly different (p > 0.05 before treatment) between groups but was reduced significantly (p < 0.05 after treatment) in both groups (30 +/- 9 mm Hg before vs. 9 +/- 4 mm Hg after myotomy, and 27 +/- 10 mm Hg before vs. 11 +/- 4 mm Hg after pneumatic dilation. The total time the pH was < 4.0 was not significantly different, p > 0.05, in either group before treatment (myotomy, 3.7 +/- 4.4%; dilation, 2.9 +/- 4.9%) or after treatment (myotomy, 8.6 +/- 9.2%; dilation, 10.2 +/- 15.9%). Twelve of 32 patients (38%), had a percent total time < 4.0 that exceeded 6% after treatment, eight of whom were asymptomatic. CONCLUSIONS: These results indicate that the amount of reflux after treatment by both pneumatic dilation and transthoracic esophagomyotomy is similar. The absence of reflux symptoms in treated achalasia patients does not exclude the possibility of significant acid reflux.

Ambulatory esophageal pH testing. Referral patterns, indication, and treatment in a Canadian teaching hospital.

Over a 30-month period, 867 esophageal pH studies were conducted in a Canadian teaching hospital; of these, 315 tests were recorded in patients who were first-time referrals having no chest or upper gastrointestinal surgery and taking no medication that would affect the results. Patients were referred by gastroenterologists, general surgeons, ENT surgeons, thoracic surgeons, and a miscellaneous group. Patients were classified based on: pH results [abnormal = % total time pH < 4.0 (ie, > 6.0%)], manometry (abnormal = LES resting pressure < 5 mm Hg and/or abnormal peristalsis), and gender. Fifty-one percent (162/315) of the patient records demonstrated abnormal reflux. Intergroup comparisons of severity of reflux using two-way analysis of variance demonstrated no significant differences (P = 0.13). In the 162 patients who refluxed, 70% (N = 108) had normal motility studies; however, when the severity of reflux was compared, patients with abnormal motility (N = 54) demonstrated significantly more severe reflux (19.8 +/- 12.8 vs 16.2 +/- 11.3) P = 0.02. In those patients with abnormal manometry, no significant differences (P = 0.44) in the severity of reflux were found among those with abnormal peristalsis (N = 27), low resting pressure (N = 17), or a combination of aperistalsis and low LES pressure (N = 10). Symptomatic patients with reflux (N = 107) demonstrated a significantly greater percent time pH < 4.0 than those with asymptomatic reflux (N = 55); 18.1 +/- 11.5% vs 16.2 +/- 12.7%, P = 0.04. When the severity of reflux by gender was compared, no significant differences were found [18.3 +/- 11.9 (male) N = 91 vs 16.2 +/- 11.9 (female) N = 71, P = 0.11]. The results from this study show that: (1) esophageal pH testing is important in subspecialties other than gastroenterology and that the clinical yield is high in all referring groups, (2) esophageal pH testing and manometry are complimentary tests, but that reflux occurs commonly in association with normal manometry, (3) asymptomatic reflux was found in 34% of the patients with abnormal reflux scores, and (4) the severity of reflux in male and female patients is similar.

Reproducibility of ambulatory esophageal pH monitoring in the aperistaltic esophagus.

The reproducibility of ambulatory 24-h esophageal pH monitoring was evaluated in 16 consecutive patients by comparing the difference in two consecutive 24-h periods. The study group included 8 patients with scleroderma esophagus and 8 treated achalasia patients. The amount of reflux was expressed as the percentage of time the pH was < 4.0. Both groups demonstrated excellent intrapatient reproducibility overall: 96% in scleroderma patients and 95% in those patients with achalasia. The least concordance was found in the lengths of the longest reflux events-70% when supine in scleroderma patients and 59% when upright in patients with achalasia. There was no significant difference (p > 0.05) between day 1 and day 2 for either group of patients for any of the elements studied. These results indicate that intrapatient variability of gastroesophageal reflux in patients with scleroderma esophagus and treated patients with achalasia is very low and following therapeutic intervention, a high level of confidence can be placed in subsequent pH monitoring as an indicator of treatment effect.

Reflux in untreated achalasia patients.

We made a prospective assessment of acid exposure in the distal esophagus in 48 consecutive untreated patients with achalasia using 24-h ambulatory esophageal pH studies. The majority of patients (38/48) experienced reflux that was within reported values for normal controls (total time pH < 4.0, 1.8 +/- 1.9%). Approximately 20% (10/48), however, demonstrated abnormal acid exposure (total time pH < 4.0, 18.8 +/- 14.8%). The difference in reflux expressed by these two groups was not due to a significant difference in lower esophageal sphincter pressure (p > 0.05) or retained food. An in vitro model of lactobacillus fermentation supported the contention that true acid reflux accounted for changes in esophageal pH. Repeat pH studies were obtained in 23 patients following treatment: 15 underwent pneumatic dilatation and 8 underwent limited myotomy. Although no significant differences were found between pre- and posttreatment reflux, some patients undergoing either treatment were found to demonstrate increased acid exposure. In conclusion, we believe that patients with achalasia should be tested by pH study both before and after treatment. Most of the patients who demonstrated significant pretreatment reflux were asymptomatic, and both methods that were used to decrease resting sphincter pressure were shown to be able to increase distal acid exposure.

Comparison of magnetic resonance imaging and endoscopy in distinguishing the type and severity of inflammatory bowel disease.

Twenty consecutive patients with first-time presentation of suspected inflammatory bowel disease underwent both endoscopy with biopsy and magnetic resonance imaging (MRI) within a 3-day period; the relative abilities of endoscopy and MRI to distinguish ulcerative colitis (UC) from Crohn's disease (CD) and to determine the severity of the disease process were compared. In 18 of 20 patients, a diagnosis of UC or CD could be made on histological specimens. MRI correctly diagnosed 17 of these 18 patients using T1-weighted fat-suppressed spin echo and gadolinium enhancement. Endoscopy correctly diagnosed 15 patients. Overall, MRI was not significantly better (p > 0.05) than endoscopy in distinguishing UC from CD. MRI correctly graded the severity of inflammatory changes in 13 of 20 patients, and endoscopy did so in 11 of 20. MRI and endoscopy findings were within one grade of histology findings in seven patients each. No significant difference (p > 0.05) was found between MRI and endoscopy in the ability to estimate the severity of the disease (as determined from biopsies). Bowel wall thickness measured on MR images demonstrated good correlation with percentage of contrast enhancement: r = 0.61; p = 0.003. In sum, magnetic resonance imaging was shown to be comparable with endoscopy in differentiating UC from CD and in gauging the severity of disease. Transmural assessment, sagittal imaging, and the lack of invasiveness were attractive features of MRI.

Solitary hepatic metastasis: comparison of dynamic contrast-enhanced CT and MR imaging with fat-suppressed T2-weighted, breath-hold T1-weighted FLASH, and dynamic gadolinium-enhanced FLASH sequences.

Twenty consecutive cancer patients with a solitary hepatic metastasis detected with dynamic contrast-material-enhanced computed tomography (CT) who were considered for hepatic resection underwent magnetic resonance (MR) imaging within 18 days after CT. Histologic confirmation was obtained in all lesions. CT depicted 20 solitary lesions. MR imaging showed a solitary lesion in 14 patients, two lesions in three patients, and more than two lesions in three patients, for a total of 37 lesions. Twenty-three lesions less than 2 cm in diameter were missed with CT, and six lesions less than 1.3 cm in diameter were missed with MR imaging. MR imaging was superior to CT in the detection of hepatic metastases on a patient-by-patient basis (P < .01). The results suggest that MR imaging is superior to dynamic contrast-enhanced CT for the detection of hepatic metastases.

MRI in the diagnosis of Crohn's disease in two pregnant women.

Two pregnant women considered symptomatic for inflammatory bowel disease were referred for magnetic resonance imaging (MRI) for assistance in establishing a diagnosis. Breath-hold gradient echo and contrast-enhanced T1-weighted fat-suppressed spin echo sequences were used. The MR appearance of the terminal ileum was consistent with Crohn's disease in both patients. The diagnosis of Crohn's disease was subsequently confirmed histologically. MRI is a safe, noninvasive modality that may be useful in confirming a suspected diagnosis of inflammatory bowel disease, especially in patients who cannot be evaluated with standard techniques.

Magnetic resonance imaging evaluation of the local extent of colorectal mass lesions.

Magnetic resonance imaging (MRI) was conducted in 21 patients with known or suspected colorectal mass lesions. Imaging was carried out at 1.5 T using Fast Low Angle Shot (FLASH) and fat-suppressed (T1FS) gadolinium enhanced sequences. The lesions studied included adenocarcinoma (n = 16), lipoma (n = 2), villous adenoma with foci of adenocarcinoma (n = 1), malignant melanoma (n = 1), and rectal lymphoma (n = 1). Correlation was made with surgical findings in 14 patients, 10 of whom had tumors resected. Bowel wall involvement, tumor size, and extension demonstrated on MR images was correlated with histopathology findings. No significant differences were found (p > 0.05) among those parameters when compared to MR information from T1FS images. Lymph nodes were demonstrated on MR images but distinction between benign and malignant nodes could not be made.

Magnetic resonance imaging in inflammatory bowel disease.

Magnetic resonance (MR) images were acquired in 28 consecutive inflammatory bowel disease (IBD) patients undergoing medical treatment. The protocol employed included i.v. gadopentatate dimeglumine, pre- and post-contrast breath-hold Fast Low Angle Shot (FLASH), and fat-suppressed spin echo imaging. The percent contrast enhancement (% CE) of the fat-suppressed images was compared with severity of inflammation based on endoscopic and/or surgical findings. The %CE of the contrast-enhanced images was 169% +/- 63 in cases of severe inflammation (n = 16), 97% +/- 38 in moderate inflammation (n = 8), and 49% +/- 26 in mild inflammation (n = 4). Significant correlations were found between the clinicopathologic findings and (a) % CE, r = 0.74 (p = 0.0001); (b) length of affected bowel segment, r = 0.49 (p = 0.007); and (c) bowel wall thickness, r = 0.42 (p = 0.02). In a subsequent comparison, %CE was correlated with length of affected bowel and bowel wall thickness. The best correlation was bowel wall thickness, r = 0.53 (p < 0.004). Good correlation was found between MR findings and pathology/histology findings in the determination of bowel wall thickness, length of diseased bowel, and severity of inflammation in 10 patients who underwent bowel resection. The results of this study show that MR images demonstrate the extent and severity of inflammatory changes in the GI tract, which correlate with endoscopic and histological findings.

Islet cell tumors: comparison of dynamic contrast-enhanced CT and MR imaging with dynamic gadolinium enhancement and fat suppression.

Ten patients with 11 islet cell tumors underwent dynamic contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging within a 1-month period. MR imaging depicted all 11 tumors, and CT depicted seven of the 11 tumors. CT did not depict four of seven tumors that measured 2.5 cm in diameter or less. Islet cell tumors had low signal intensity on T1-weighted fat-suppressed MR images, and gastrinomas were best shown with this technique. Two of three insulinomas less than 1.5 cm in diameter were best shown on dynamic contrast-enhanced fast low-angle shot (FLASH) images as uniform areas of high signal intensity. Hepatic metastases were seen in five patients and showed peripheral ringlike enhancement best demonstrated on dynamic gadolinium-enhanced FLASH images. Hepatic lesions were most conspicuous on T2-weighted fat-suppressed spin-echo images. MR imaging with dynamic gadolinium enhancement and fat suppression is a promising tool in the investigation of islet cell tumors.

Bile duct disease: prospective comparison of ERCP, CT, and fat suppression MRI.

The authors compared computed tomography (CT) and endoscopic retrograde cholangiopancreatography (ERCP), techniques commonly used to study the biliary tree, with pre- and post-Gd-DTPA breath-hold fast low angle shot (FLASH) and fat suppressed spin-echo in 28 consecutive patients with bile duct abnormalities detected on ERCP, including 11 patients with malignant disease and 17 patients with benign disease. ERCP, CT, and magnetic resonance (MR) images were prospectively interpreted in a blinded fashion and reviewed by consensus. ERCP characterized all cases of malignant disease by the presence of a narrowed bile duct lumen with irregular margins. CT and MRI detected all cases of malignant disease and characterized nine of 11 as malignant. In seven of these cases, CT and MRI showed thickening of extrahepatic bile duct walls greater than 5 mm. MRI images showed intrahepatic-enhancing periportal tissue in four cases, which was not seen on CT images, and which was biopsy-proven tumor extension. Benign disease was characterized on ERCP images by the demonstration of smooth tapered narrowings in 16 cases, whereas on CT and MR images it was characterized by mild to moderate dilatation of the intrahepatic bile ducts and wall thickness less than 5 mm in 13 cases. Overall ERCP correctly characterized 27 cases as benign or malignant and CT and MRI both characterized 25. The results of this study show a trend that ERCP is superior to CT and MRI for characterizing bile duct disease.

Pancreatic disease: prospective comparison of CT, ERCP, and 1.5-T MR imaging with dynamic gadolinium enhancement and fat suppression.

New magnetic resonance (MR) imaging techniques possess features desirable for imaging the pancreas. Computed tomography (CT) and endoscopic retrograde cholangiopancreatography (ERCP) were prospectively compared with breath-hold fast low-angle shot (FLASH) and fat-suppressed spin-echo techniques before and after enhancement with gadopentetate dimeglumine. Thirty-five patients underwent ERCP, CT, and/or MR imaging studies within a 1-month period. Correlation with surgical findings, histologic findings, or clinical and/or imaging follow-up was obtained in all cases. Quantitative measurements of pancreas, pancreas minus pancreatic lesion, and pancreas minus fat signal-to-noise ratios (SNRs) were performed on MR images. The highest measurements of pancreas minus pancreatic tumor SNR were on gadolinium-enhanced, fat-suppressed images (8.9 +/- 3.4). The 1-second postcontrast FLASH images most reliably showed enhancement of normal pancreatic tissue. Nonenhanced FLASH images depicted peripancreatic fluid and inflammatory changes most successfully. The findings from this study suggest MR imaging is effective for imaging inflammatory and neoplastic pancreatic disease and may be superior to CT.

Bowel disease: prospective comparison of CT and 1.5-T pre- and postcontrast MR imaging with T1-weighted fat-suppressed and breath-hold FLASH sequences.

The potential of new high-field-strength magnetic resonance (MR) imaging sequences to evaluate bowel disease was investigated and compared with computed tomographic (CT) studies. Thirty-two patients were studied, 14 with known or suspected gastrointestinal tumors and 18 with known or suspected bowel inflammatory conditions. T1-weighted fat-suppressed spin-echo and breath-hold FLASH (fast low-angle shot) images were obtained before and after intravenous injection of 0.1 mmol/kg gadopentetate dimeglumine. Pathologic confirmation was obtained by biopsy (n = 18), surgical excision (n = 8), or endoscopy (n = 6). CT and MR images were analyzed separately in a prospective fashion and reviewed by consensus. Information from CT and MR images was comparable in cases of confirmed bowel neoplasia. CT scans had better spatial resolution, while fat-suppressed gadolinium-enhanced MR images had better contrast resolution. In the 18 cases of bowel inflammation, CT scans showed concentric wall thickening in 16, while MR images showed concentric wall thickening in 14 and increased contrast enhancement in 17. Contrast enhancement was better appreciated on fat-suppressed images than on FLASH images. The results suggest that MR imaging may play a role in the evaluation of bowel disease.

The effect of transcutaneous electric nerve stimulation on postoperative pain and pulmonary function.

Surgery on the upper abdomen is associated with marked postoperative pulmonary dysfunction that results largely from restriction of lung expansion secondary to incisional pain. This study, utilizing three groups of patients (a control group, a sham group, and a group receiving transcutaneous electric nerve stimulation [TENS] for pain control), was designed to determine whether this modality is effective in alleviating postoperative pain. Spirometry, arterial blood gases, clinical as well as radiologic evidence of postoperative pulmonary complications, and the frequency of analgesic requests were determined. Of the 40 patients studied, the 15 receiving TENS required only 4.7 +/- 2.5 doses of narcotic analgesics in the first 72 hours as opposed to 10.1 +/- 2.7 and 10.4 +/- 2.7 in the other two groups (P less than 0.005). There were a total of six postoperative pulmonary complications, all occurring in the groups not receiving TENS. Postoperative arterial Po2, vital capacity, and functional residual capacity were least depressed in the TENS group. The data suggest that TENS minimizes the tendency toward postoperative alteration in respiratory mechanics and decreases the incidence of pulmonary complications by alleviating incisional pain.