Influence of body position and stool characteristics on defecation in humans.

BACKGROUND: Whether defecation is influenced by body position or stool characteristics is unclear. AIM: We investigated effects of body position, presence of stool-like sensation, and stool form on defecation patterns and manometric profiles. METHODS: Rectal and anal pressures were assessed in 25 healthy volunteers during attempted defecation either in the lying or sitting positions and with balloon-filled or empty rectum. Subjects also expelled a water-filled (50 cc) balloon or silicone-stool (FECOM) either lying or sitting and rated their stooling sensation. RESULTS: When attempting to defecate in the lying position, a dyssynergic pattern was seen in 36% of subjects with empty rectum and 24% with distended rectum. When sitting, 20% showed dyssynergia with empty rectum and 8% with distended rectum. More subjects (p < 0.05) showed dyssynergia in lying position. When lying, 60% could not expel balloon and 44% FECOM. When sitting, fewer (p < 0.05) failed to expel balloon (16%) or FECOM (4%). FECOM expulsion time was quicker (p < 0.02). Stool-like sensation was more commonly (p < 0.005) evoked by FECOM than balloon. CONCLUSIONS: In the lying position, one-third showed dyssynergia and one-half could not expel artificial stool. Whereas when sitting with distended rectum, most showed normal defecation pattern and ability to expel stool. Thus, body position, sensation of stooling and stool characteristics may each influence defecation. Defecation is best evaluated in the sitting position with artificial stool.

Ambulatory 24-hour colonic manometry in slow-transit constipation.

BACKGROUND: The colonic neuromuscular dysfunction in patients with constipation and the role of colonic manometry is incompletely understood. AIM: To study prolonged colonic motility and assess its clinical significance. METHODS: Twenty-four-hour ambulatory colonic manometry was performed in 21 patients with slow-transit constipation and 20 healthy controls by placing a 6-sensor solid-state probe up to the hepatic flexure. Quantitative and qualitative manometric analysis was performed in 8-h epochs. Patients were followed up for 1 yr. RESULTS: Constipated patients showed fewer pressure waves and lower area under the curve (p < 0.05) than controls during daytime, but not at night. Colonic motility induced by waking or meal was decreased (p < 0.05) in patients. High-amplitude propagating contractions (HAPCs) occurred in 43% of patients compared to 100% of controls and with lower incidence (1.7 vs 10.1, p < 0.001) and propagation velocity (p < 0.04). Manometric features suggestive of colonic neuropathy were seen in 10, myopathy in 5, and normal profiles in 4 patients. Seven patients with colonic neuropathy underwent colectomy with improvement. The rest were managed conservatively with 50% improvement at 1 yr. CONCLUSIONS: Patients with slow-transit constipation exhibited either normal or decreased pressure activity with manometric features suggestive of colonic neuropathy or myopathy as evidenced by absent HAPC or attenuated colonic responses to meals and waking. In refractory patients, colonic manometry may be useful in characterizing the underlying pathophysiology and in guiding therapy.

Local anesthetic resistance in a pregnant patient with lumbosacral plexopathy.

BACKGROUND: We report a case of a patient with apparent resistance to local anesthetics. While similar cases of failure of regional anesthetics are often attributed to technical failure, the overall clinical presentation and history of this patient suggests a true resistance to local anesthetics. CASE PRESENTATION: This patient presented for elective cesarean section and the decision for regional anesthesia was made. While attempting to place an epidural, the patient failed to achieve adequate skin analgesia despite multiple attempts at local infiltration. When a spinal was ultimately placed, sensory or motor blockade was not obtained despite no evidence of technical problems with technique. Further questioning revealed multiple prior episodes of local anesthetic failure in this patient. CONCLUSIONS: While the failure rate of spinal anesthesia has been shown range from 4-13% and is often attributed to technical failure, elements of this particular case suggest a true resistance to local anesthetics.