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.

Cerebral pressure-flow relationship during cardiopulmonary bypass in the dog at normothermia and moderate hypothermia.

We studied cerebral autoregulation by analyzing cerebral pressure-flow curves during cardiopulmonary bypass (CPB) with alpha-stat (alpha-stat) acid-base management at 28 (n = 9) and 37 degrees C (n = 9) in two groups of dogs. Cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) were determined multiple times in each animal over an extensive range of cerebral perfusion pressure (CPP). The CPP was altered by changing perfusion flow rate. The dependence of CBF on CPP during normothermic and moderate hypothermic CPB was assessed using a block design analysis of covariance with CPP as the covariate. We anticipated maximal statistical power with this analysis to define if cerebral autoregulation was intact. This method of statistical analysis was compared with the conventional interpretation by linear regression analysis. Animals were administered sodium thiopental until an isoelectric electroencephalogram was obtained to assure stable depth of anesthesia independently of temperature effects. The animals were randomly assigned to either temperature group. The CBF was determined by injection of radioactive microspheres at each of five target CPPs randomly allocated (50, 60, 70, 80, and 90 mm Hg). The brain oxygen content difference was defined as arterial minus superior sagittal sinus (SSS) oxygen content. No difference in CPP, hemoglobin, arterial carbon dioxide tension, or pH was seen between groups at any time period. In both groups, total CBF (tCBF) increased significantly with increasing CPP (p = 0.012 and 0.017 for normothermic and hypothermic CPB, respectively; CPP as covariate). The between-group difference in slopes (CPP x temperature effect) approached statistical significance (p = 0.059).(ABSTRACT TRUNCATED AT 250 WORDS)

Paraplegia following thoracic aortic cross-clamping in dogs. No difference in neurological outcome with a barbiturate versus isoflurane.

BACKGROUND AND PURPOSE: We compared the incidence and severity of paraplegia following thoracic aortic cross-clamping in dogs for two anesthetic regimens. Animals were randomly assigned to receive methohexital (group M; n = 9) or isoflurane (group I; n = 9). We expected a better neurological outcome in animals administered methohexital because of superior neuronal protection and greater spinal cord perfusion pressure (mean arterial pressure below the cross-clamp site minus mean cerebrospinal fluid pressure). METHODS: After surgical preparation and a 30-minute stabilization period, dogs in group M received 14 +/- 6 mg.kg-1 i.v. methohexital to induce an isoelectric electroencephalogram followed by a continuous infusion of methohexital at 20 mg.kg-1 x h-1. Dogs in group I received 1.4 +/- 0.2% end-tidal isoflurane (1 minimum alveolar concentration). The thoracic aorta was then occluded 2.5 cm distal to the left subclavian artery for 30 minutes and then released. Hemodynamics and cerebrospinal fluid pressure were measured at (1) baseline, (2) 2 minutes after aortic cross-clamping, (3) 20 minutes after aortic cross-clamping, (4) 5 minutes after aortic unclamping, and (5) 30 minutes after resuscitation. At 24 hours a neurological assessment was performed. After the clinical assessment the dogs were killed and the spinal cord removed immediately for histopathologic study. RESULTS: There were no differences in nasopharyngeal temperature, PaCO2, pH, or hemoglobin at any time between groups. With cross-clamping, the spinal cord perfusion pressure decreased precipitously. However, there was no difference in spinal cord perfusion pressure between groups at any time (P = .5555). The neurological outcome, assessed at 24 hours after thoracic aortic cross-clamping by a veterinarian unaware of the anesthetic protocol, was not different between groups (P > .5, two-tailed Mann-Whitney rank-sums test). When anesthetized with methohexital 5 of 9 dogs were paraplegic; with isoflurane 7 of 9 dogs were paraplegic. By Spearman's rank test, a strong inverse correlation between the Tarlov score and the ratio of dead to total lumbar anterior spinal cord neurons was seen (Spearman's correlation coefficient = -.8358; P = .0001). CONCLUSIONS: We conclude that no advantage was offered by the choice of anesthesia to neurological outcome after 30 minutes of thoracic aortic cross-clamping in this canine model.

Treatment of proximal aortic hypertension after thoracic aortic cross-clamping in dogs. Phlebotomy versus sodium nitroprusside/isoflurane.

Thoracic aortic cross-clamping causes proximal aortic hypertension. Theoretically, the method used to treat hypertension can influence spinal cord perfusion pressure and neurologic outcome. Phlebotomy was compared to sodium nitroprusside/isoflurane in terms of ability to treat increased proximal mean aortic pressure (MAPp) after thoracic aortic cross-clamping in dogs. Dogs were assigned randomly to one of three groups depending on the method used to treat hypertension after cross clamping: 1) phlebotomy (n = 10); 2) sodium nitroprusside/isoflurane (n = 11); and 3) control (no treatment) (n = 8). In each dog, anesthesia was maintained with isoflurane in oxygen, 1.4% end-tidal. The thoracic aorta was occluded 2.5 cm distal to the left subclavian artery for 50 min and then was released. Hemodynamics, cerebrospinal fluid pressure (CSFP), and regional blood flows by the radioactive microsphere technique, were measured at 1) baseline; 2) 2 min after aortic cross-clamping; 3) after treatment of proximal aortic hypertension; 4) 5 min after aortic unclamping; and 5) 30 min after resuscitation. At 24 h, a neurologic assessment was performed. Thoracic aortic cross-clamping increased MAPp, decreased distal MAP (MAPd), and reduced lumbar spinal cord perfusion pressure (SCPPl), [SCPPl = MAPd - CSFP], in all three groups. Control of increased MAPp necessitated removal of 36 +/- 9 ml/kg of blood in the phlebotomy group. In the sodium nitroprusside/isoflurane group, sodium nitroprusside (16 micrograms.kg-1.min-1) was infused and end-tidal isoflurane concentration increased to 2.5 +/- 0.7%, restoring MAPp to baseline level.(ABSTRACT TRUNCATED AT 250 WORDS)

Phlebotomy reverses the hemodynamic consequences of thoracic aortic cross-clamping: relationships between central venous pressure and cerebrospinal fluid pressure.

In dogs (n = 11) anesthetized with sodium pentobarbital (to an isoelectric EEG), the authors investigated the influence of thoracic aortic cross-clamping (AXC) on systemic hemodynamics and cerebrospinal fluid pressure (CSFP) with concurrent measurement of total brain flow (tCBF) and regional (cervical, thoracic, and lumbar) spinal cord blood flow (SCBF). The effect of phlebotomy (to control the hemodynamic consequences of AXC) on tCBF and SCBF was assessed. Radioactive microspheres were injected at four time periods in each animal: 1) at baseline; 2) with application of the AXC; 3) after phlebotomy, to reduce the proximal mean arterial pressure (MAPp) to baseline values; and 4) 2 min after removal of the AXC (mean AXC time 68 +/- 6 min). With application of the AXC, the MAPp, central venous pressure (CVP), and CSFP significantly increased (104 +/- 6 to 156 +/- 6 mmHg, 3.4 +/- 0.4 to 5.2 +/- 0.7 mmHg, and 3.3 +/- 0.7 to 5.2 +/- 0.8 mmHg, respectively), while distal mean aortic pressure (MAPd) significantly decreased (98 +/- 6 to 14 +/- 1 1 mmHg). Phlebotomy (24 +/- 3 ml.kg-1) significantly decreased MAPp (to 106 +/- 6 mmHg), CVP (to 1.6 +/- 0.6 mmHg), and CSFP (to 1.2 +/- 1.1 mmHg). The CSFP changed in parallel with the changes in CVP, a result suggesting that the alterations in CSFP depended on cardiac preload. The spinal cord perfusion pressure (SCPP; SCPP = MAPd - CSFP) was unchanged after phlebotomy, since both MAPd and CSFP decreased. The tCBF and cervical SCBF were unchanged when MAPp increased by 50% with application of the AXC; this indicated that autoregulation was intact.(ABSTRACT TRUNCATED AT 250 WORDS)

Esophageal reflux before and after isolated myotomy for achalasia.

Four patients with achalasia underwent 24-hour esophageal pH measurements as ambulatory patients before and after limited myotomy without fundoplication. Resting lower esophageal sphincter pressure was reduced from 24.3 +/- 1.3 mm Hg to 7.5 +/- 4.3 mm Hg. No significant differences (p greater than 0.05) were found before and after operation in the total 24-hour pH data distribution (pH 6.24 +/- 0.84 vs 5.75 +/- 1.03), the fraction of time below pH 4.0 (4.8% +/- 5.3% vs 8.0% +/- 6.9%), or the mean duration of reflux episodes greater than 5 minutes (22.8 +/- 18.8 minutes vs 23.0 +/- 10 minutes), all +/- SD. Effective relief of esophageal obstruction in achalasia is feasible by isolated limited myotomy without producing gastroesophageal reflux.

Reflux patterns in patients with achalasia without operation.

Five patients with achalasia who had not had an operation underwent esophageal manometry and 24-hour, ambulatory pH monitoring to determine the pattern and extent of esophageal reflux. One patient had reflux within normal limits. In 2 patients, reflux occurred 0.5% of the total time and no episodes of supine reflux were recorded. In the 2 remaining patients, reflux was measured 16.8% and 55.3% of the total time; however, in both patients, these results were influenced by lengthy bouts of supine reflux. These indices of reflux were not influenced by differences in resting lower esophageal sphincter tone, position, or length. Twenty-four-hour esophageal pH monitoring can be useful in the preoperative assessment of patients with achalasia, and the information obtained might influence the choice of operative procedure.

Reflux patterns following limited myotomy without fundoplication for achalasia.

Five patients with achalasia underwent limited myotomy without fundoplication. Surgery reduced mean lower esophageal sphincter resting pressure significantly (p less than .05) from 31 +/- 9.7 mm Hg to 16.1 +/- 8.2 mm Hg. Twenty-four-hour ambulatory esophageal pH studies demonstrated that the percentage of time the pH in the distal esophagus was below 4 was similar whether the patient was upright or supine (6.6 +/- 6.5% of total time upright vs. 9.1 +/- 12.7% of total time). Reflux events that occur in the supine position may be significant because of their prolonged duration resulting from the absence of normal secondary peristalsis in the body of the esophagus. Patients with achalasia who have undergone esophagomyotomy without fundoplication do not appear to experience more reflux than control subjects with normal esophageal function.

Surgical management of recurrent spontaneous pneumothorax during pregnancy.

We report three cases of recurrent spontaneous pneumothorax associated with pregnancy. All three cases had apical bullectomies during their pregnancies.

Risks and benefits of open-heart surgery in patients 70 years of age and older.

From January 1978 to December 1982, 165 consecutive patients aged 70 to 81 years underwent various open-heart surgical procedures at the St. Boniface General Hospital in Winnipeg. Preoperatively, most of the patients were in functional class III or IV (New York Heart Association classification). Overall operative mortality for the series was 10.9%. Isolated coronary artery bypass surgery, performed in 71 patients, had an operative mortality of 2.8%. Results were also good in isolated single and double valve replacement in 58 patients (operative mortality 8.6%); there were no deaths in a group of 27 patients who underwent isolated aortic valve replacement. Thirty-six patients with various combined, extensive procedures had the poorest result (operative mortality 30.5%). More than 90% of surviving patients were in functional class I or II postoperatively. The complication rate, although high, was acceptable. Immediate and long-term clinical improvement in the majority of patients justifies a surgical approach except in patients who require combined, extensive procedures.