Effect of urethral stimulation on vesical contractile activity

BACKGROUND: We investigated the hypothesis that urethral stimulation effects vesical contraction. METHODS: Vesical pressure response to urethral balloon distension with normal saline in increments of 1 mL was recorded in 26 healthy volunteers (17 men, 9 women; mean age, 36.9 +/- 9.7 SD years) before and after individual anesthetization of the urinary bladder and urethra. Urethral distension was effected by a 6F balloon-ended catheter introduced per urethra. Vesical pressure was measured by means of a microtip catheter. RESULTS: Vesical pressure recorded gradual increase on increase of urethral balloon distension. Bladder response was maintained as long as urethral distension was continuous. The response showed no significant difference when we distended different parts of the male or female urethrae. Urethral distension after individual vesical and urethral anesthetization effected no change in the vesical pressure. CONCLUSIONS: Urethral distension produced a vesical pressure increase that presumably denotes vesical contraction. Vesical contraction on urethral stimulation by distension is suggested to be mediated through a "urethrovesical stimulating reflex" that seems to facilitate vesical contraction. Provided further studies to be performed in this respect, the reflex may prove to be of diagnostic significance in micturition disorders.     

Effect of rectal distension on the small intestine with evidence of a recto-enteric reflex

BACKGROUND/AIMS: To study the effect of rectal distension on jejunal and ileal motility aiming at the assessment of the possible role of rectal distension induced by constipation on the transport of the material in the gut. METHODOLOGY: The rectum of 16 healthy volunteers (mean age: 38.6 +/- 11.7 years, 10 men, and 6 women) was distended by a balloon filled with water in increments of 50 mL up to 200 mL and the response of the jejunal and ileal pressures was recorded. The test was repeated distending the anesthetized rectum 20 min and 3 hours after anesthetization. RESULTS: Rectal distension with 50 mL of water effected no jejunal or ileal pressure changes (P > 0.05). One hundred-mililitre (100-mL) rectal distension produced decrease of jejunal and ileal pressures (P < 0.05) which lasted as long as distension was maintained. Rectal distension with 150 and 200 mL caused jejunal and ileal pressure response similar to that of the 100 mL distension (P > 0.05). Distension of the anesthetized rectum effected no significant jejunal or ileal pressure changes. CONCLUSIONS: The results were reproducible in the individual subject. The decline of the intestinal pressure upon rectal distension postulates a reflex relationship between the 2 conditions. This reflex nature is evidenced by reproducibility and by its absence on distension of the anesthetized rectum. We termed this reflex relation: "recto-enteric reflex". It is suggested that under normal physiologic conditions the reflex inhibits the intestinal transit, thus giving the rectum time to evacuate itself. Continuous rectal distension, as occurs in inertia constipation, appears to effect enteric hypotonia, a hypothesis which requires further studies.     

Rectal reservoir and sensory function studied by graded isobaric distension in normal man.

The rectal expansion and concomitant sensory function on graded, isobaric, rectal distension within the interval 5-60 cm H2O was investigated in 36 healthy young volunteers. Anal pressure and electromyography (EMG) from the external anal sphincter were simultaneously recorded. Rectal distension caused an initial rapid expansion followed by transient, often repeated, reflex rectal contractions and a slow gradual increase of rectal volume. The maximal volume displaced by the first reflex rectal contraction was 18 (13) ml, which was less than 10% of the volume at 60 s. The pressure threshold for appreciation of rectal filling was 12 cm H2O (95% CL 5-15 cm H2O) and coincided with the threshold for rectoanal inhibition. Urge to defecate was experienced at 28 cm H2O (15-50 cm H2O) distension pressure, which was close to the threshold for maximal rectal contraction, also coinciding with the appearance of the external anal sphincter reflex. The interindividual variation of rectal volume on distension with defined pressures varied widely, indicating a considerable variation of rectal compliance in normal man. No correlation was found between rectal volume and sex or anthropometric variables. The relative variations in pressure thresholds for eliciting rectal sensation and rectoanal reflexes were less than the corresponding threshold volumes. It was concluded that the dynamic rectal response to distension reflects a well graded reflex adjustment ideal for a reservoir.     

Ischemia potentiates the reflex bronchodilation evoked by static muscular contraction in dogs

In eleven anesthetized dogs, we found that static contraction of hindlimb muscles that were freely perfused decreased total lung resistance by 0.7 +/- 0.1 cm H2O.L-1.sec, whereas static contraction of the same muscles rendered ischemic decreased total lung resistance by 1.5 +/- 0.4 cm H2O.L-1.sec (P less than 0.025). In ten other dogs, we found that static contraction of freely perfused hindlimb muscles decreased total lung resistance by 0.9 +/- 0.2 cm H2O.L-1.sec, whereas dynamic contraction of the same freely perfused muscles decreased total lung resistance by 1.1 +/- 0.3 cm H2O.L-1.sec. The difference in the magnitudes of the bronchodilator responses to the two modes of contraction was not significant (P greater than 0.05). We conclude that a mismatch between blood supply and demand in working skeletal muscle increases the reflex bronchodilator response to static contraction. We also conclude that dynamic contraction evokes a reflex bronchodilation equivalent to that evoked by static contraction provided that the tension produced by the two modes of contraction are equal.     

Preservation of complete anal sphincteric proprioception in restorative proctocolectomy: the inhibitory reflex and fine control of continence need not be impaired.

This study evaluates whether reflux function of the anal sphincter remains unchanged after restorative proctocolectomy, provided that the sphincter remaining is kept intact, without mucosal stripping or endo-anal anastomosis. Paired tests of anorectal function were performed before, and a median of 6 (range 2-12) months after restorative proctocolectomy with stapled, end to end pouch-anal anastomosis. Beforehand, distension of the rectum with 50 ml of air produced a median (interquartile range) increase in pressure within the rectum of 22 (15-29) cm H2O and reflex inhibition of the anal sphincter from a pressure of 76 (62-106) cm H2O to a pressure of 34 (15-52) cm H2O. After the procedure, distension of the ileal pouch with 50 ml of air produced an increase in pressure within the pouch of only 5 (4-8) cm H2O (p < 0.001 compared with beforehand) and reflex inhibition of the anal sphincter from a pressure of 62 (25-79) cm H2O to 37 (17-68) cm H2O. Maximal reflex inhibition of the upper third if the anal sphincter to a pressure of 26 (15-48) cm H2O was observed when pressure within the pouch increased by 16 (11-22) cm H2O. After restorative proctocolectomy, all patients were continent (two experienced minor nocturnal leakage of mucus) and 25 could discriminate between flatus and faeces. Thus, reflux function was preserved in response to changes in pressure, ensuring that the subtler aspects of anal continence were preserved.     

Study of the effect of jejuno-ileal distension on the motor activity of the stomach with evidence of "entero-gastric inhibitory reflex"

BACKGROUND/AIMS: In chronic constipation due to delayed colonic transit, stasis of the ileal contents with resulting ileal distension may occur. The current study investigated the effect of ileal and jejunal distension on the gastric motility, aiming at elucidating the possible existence of a relationship and its role in the flow through the gut. METHODOLOGY: The response of the gastric pressure to ileal and jejunal balloon distension in increments of 2 mL of saline was recorded in 12 mongrel dogs. The test was repeated after separate local anesthetization of the ileum, jejunum and stomach. RESULTS: 2- and 4-mL ileal balloon distension produced no significant gastric pressure response, while 6- and up to 10-mL distension effected decrease of the antral and corporeal pressures (p < 0.05, p < 0.05, respectively). Jejunal distension produced a gastric pressure decline (p < 0.05) with 4 and up to 10 mL of saline. The gastric pressure decrease did not show significant changes with the various distending volumes. It was maintained as long as ileal or jejunal distension was continued. Distension of the anesthetized ileum or jejunum caused no gastric pressure changes, nor did ileal or jejunal distension produce pressure changes in the anesthetized stomach. CONCLUSIONS: The gastric pressure decline and presumably hypotonia upon ileal or jejunal distension with big volumes postulate a reflex relationship which we call "entero-gastric inhibitory reflex". The small intestine is suggested to slow down gastric emptying through this reflex. A balance is thus created between chyme delivery from the stomach and chyme processing by the small intestine. Reflex derangement in neurogenic and myogenic diseases may result in gastrointestinal disorders, a point that needs to be investigated.     

Reduction volume dependence of immunoreactive atrial natriuretic peptide secretion in isolated perfused rabbit atria

A new technique to permit gradual changes in atrial distension has been developed in an isolated perfused rabbit atrium preparation. Graded volume reduction in the atrium was induced by changing the elevation of the outflow catheter tip. Pressure reduction from 6 cm H2O atrial distension resulted in a decrease in atrial distension volume. Atrial distension by 6 cmH2O did not change the release of immunoreactive atrial natriuretic peptide (irANP). The graded reduction in atrial distension from 0.11 +/- 0.03 (1.5 cm H2O) to 1.36 +/- 0.19 microliters/mg wet weight (6.0 cm H2O) resulted in 1.7 (6.76 +/- 2.05 versus 3.83 +/- 1.18 pg/mg per min, n = 9, P less than 0.025) to 40.1-fold (77.66 +/- 17.82 versus 3.0 +/- 1.14 pg/mg per min, n = 11, P less than 0.025) increases in irANP release. IrANP release in response to the reduction of atrial distension was volume dependent. The relation of percentage increase in irANP release with the percentage reduction of atrial distension was exponential. The data suggest that the atrial muscle shortening, but not stretch per se, may be a potent direct stimulus for the regulation of irANP secretion.     

Study of the motile activity of the colon in rectal inertia constipation

BACKGROUND: We have recently demonstrated that rectal distension effected left colonic contraction, which probably acts to feed the rectum with fecal matter each time the rectum distends and evacuates its contents. This effect was postulated to occur through the recto-colic reflex. As the colonic status in rectal inertia constipation was scarcely addressed in the literature, we investigated this point. METHODS: The response of the colonic pressure to rectal balloon distension in increments of 10 mL of water was studied in 38 patients with rectal inertia constipation (IC) (age 42.6 +/- 14.3 years, 29 women) and 12 healthy volunteers (40.9 +/- 12.2 years, nine women). The rectal and colonic pressures were measured by saline-perfused tubes connected to a pneumohydraulic infusion system. The rectum was distended by a condom applied to the end of a 10-F catheter. RESULTS: The rectal and left colonic resting pressures were significantly lower in the patients than in the controls (P < 0.5, P < 0.05, respectively). In the healthy volunteers, rectal distension up to first rectal sensation produced no significant rectal or colonic pressure changes (P > 0.05, P > 0.05). At urge, rectal and left colonic pressures increased significantly (P < 0.001, P < 0.001, respectively), but there were no changes in the right colonic pressure (P > 0.05). The colonic response lasted as long as the rectum was distended. In IC, patients did not perceive the first rectal or urge sensation up to a rectal balloon filling of 300 mL; there was no rectal or colonic pressure response (P > 0.05, P > 0.05). CONCLUSION: In normal subjects, left colonic contraction on rectal distension probably acts to feed the rectum with fecal material. In IC, the low left colonic resting pressure assumedly points to left colonic hypotonia which appears to aggravate the constipation produced by the inertic rectum. Furthermore, non-response of the left colon to rectal distension probably impedes rectal feeding with fecal matter and enhances constipation.     

Evaluation of the intrinsic innervation of the internal anal sphincter using electrical stimulation.

Stimulation of the rectal mucosa with a bipolar electrode leads to relaxation of the internal anal sphincter. Intraoperative studies in two subjects showed that transmission of the impulse was independent of extrinsic nerves and was interrupted by circular myotomy. Characteristics of the reflex were studied in 11 healthy women and 19 women with severe idiopathic constipation. One control subject and two patients did not tolerate the test. In the remainder the stimulus caused a clearly defined fall in internal sphincter pressure. The mean resting maximum anal canal pressure before stimulation was the same in both groups (90 (10) v 104 (7) cm H2O, p = 0.3, controls v patients). The threshold stimulus for relaxation (12 (2) v 14 (1) mamps, p = 0.5), the maximum percent fall in resting pressure (43 (7) v 46 (4)%, p = 0.7) and the lowest absolute resting pressure produced by stimulation (48 (13) v 49 (6) cm H2O, p = 0.9) were the same in both groups. The stimulus required to achieve maximum relaxation was significantly higher in the patient group (23 (3) v 32 (2) mamps, p = 0.012) suggesting abnormal intrinsic innervation of the sphincter in these patients. Electrical stimulation should not replace balloon distension for routine testing of the rectoanal reflex but it may be useful in quantitative studies.     

Study of the effect of ileal distension on the motor activity of the jejunum, and of jejunal distension on the motor activity of the ileum

BACKGROUND/AIMS: The effect of ileal distension on the jejunal motor activity and ofjejunal distension on the ileal motility have been poorly addressed in the literature. We investigated the hypothesis that distension of either ileum or jejunum would affect the motile activity of the other. METHODOLOGY: Response of jejunal pressure to ileal balloon distension and of ileal pressure to jejunal distension in increments of 2 mL of normal saline were recorded in 18 dogs. The test was performed after individual local anesthetization of the ileum and jejunum and was repeated using saline instead of lidocaine. RESULTS: Ileal distension with 2, 4, and 6mL of saline produced no jejunal pressure response (p >0.05), while 8- and up to 12-mL distension effected jejunal pressure decrease (p<0.05). Jejunal distension up to 6mL did not change ileal pressure (p>0.05); distension with 8, 10, and 12 mL reduced it (p<0.05). Jejunal or ileal pressure responses were maintained as long as ileal or jejunal distension was continued. Distension of the anesthetized ileum or jejunum did not produce significant pressure changes in either. CONCLUSIONS: Jejunal or ileal pressure decrease and presumably hypotonia upon large-volume ileal or jejunal, respectively, distension postulate reflex relationship which we call 'ileal-jejunal and jejuno-ileal inhibitory reflex'. These reflexes appear to regulate chyme flow in small intestine by creating a balance of chyme delivery between the jejunum and ileum. Reflex derangement in neurogenic and myogenic diseases may result in gastrointestinal disorders, a point that needs to be investigated.     

Effect of unilateral pulmonary vagotomy on respiratory control in man

We studied the breathing pattern and pulmonary function at rest, and ventilatory responses to progressive hypoxia and hypercapnia in 7 awake patients who had undergone esophageal-carcinoma resection with sectioning of the right pulmonary vagal branch by lymphadenectomy. Twelve control patients, who had received the same surgery without vagotomy, were also studied by the same protocol. Two months after the operation, both patient groups demonstrated substantial depressions in FVC and FEV1.0, and slight augmentations in breathing frequency, minute ventilation, and occlusion pressure at 0.2s (P0.2) at rest. In the vagotomized group, the occlusion pressure responses to hypercapnia (delta P0.2/delta PaCO2) and hypoxia (delta P0.2/delta SaO2) in terms of response curve slope increased from 1.3 +/- 1.2 to 1.9 +/- 1.1 cm H2O/Torr and from 0.29 +/- 0.19 to 0.88 +/- 0.53 cm H2O/% (p less than 0.05), respectively. Contrary to the vagotomized patients, the nonvagotomized control group exhibited no significant changes in ventilatory chemosensitivities. Furthermore, when comparing the control and vagotomized groups, postoperative ventilatory chemosensitivity responses in terms of both hypercapnic and hypoxic occlusion pressure responses were significantly higher in the latter. We suggest that (1) due to the development of the substantial mechanical limitation in pulmonary functions, the Hering-Breuer inflation reflex became activated after surgery, and (2) a diminished Hering-Breuer reflex effect to inhibit the respiratory centers by unilateral vagotomy may have resulted in augmented ventilatory chemosensitivities.     

Effect of positive end-expiratory pressure on respiratory compliance in children with acute respiratory failure.

We studied the effect of positive end-expiratory pressure (PEEP) on the compliance of the respiratory system (Crs) in 25 children (age, 3 weeks to 10 years) requiring mechanical ventilation. Functional residual capacity (FRC) measurements were performed at 2 cm H2O increments, from 0 to 18 cm H2O of PEEP, and the FRC values were regressed versus PEEP. Static Crs, Crs/kg, and specific compliance (Crs/FRC) were calculated for each PEEP level. When FRC normality was reached Crs/kg improved in 15/25 (60%) patients but decreased in 2/25 (8%). Overall, Crs/kg increased from a mean +/- SE of 0.94 +/- 0.09 to 1.35 +/- 0.13 mL/cm H2O/kg (P = 0.003) and Crs/FRC from a mean +/- SE of 0.067 +/- 0.006 to 0.077 +/- 0.007 mL/cm H2O/mL (P = 0.057). The maximum compliance (mean Max Crs/kg, 1.56 +/- 0.12 mL/cm H2O/kg, and mean Max Crs/FRC, 0.089 +/- 0.005 mL/cm H2O/mL) was significantly higher than the compliance at the clinically chosen PEEP level and the compliance at the PEEP that normalized FRC. Maximum compliance was achieved within 4 cm H2O of the PEEP that normalized FRC. In 14/25 (60%) of cases the PEEP at maximum compliance coincided with the PEEP that resulted in FRC normalization. We concluded that static respiratory compliance improves in most (but not all) children with acute respiratory failure when FRC is normalized. Static respiratory compliance reaches maximum levels at PEEP values that are close (but not equal) to those that result in FRC normalization. Thus, assessment of the effect of PEEP on compliance is required in individual patients.     

Non-muscular factors in upper airway patency in the rabbit

The hypothesis tested in these experiments was that factors other than contraction of upper airway muscles influence the resistance of the upper airway to collapse. The intra-luminal pressures required to close and re-open the upper airway were measured in the isolated upper airways of anesthetised rabbits. The level of activity in upper airway muscles manipulated by ventilation with 100% O2 or 7% CO2 and by muscle paralysis with gallamine. During ventilation with 100% O2 closing pressure was -10.34 +/- 0.53 cm H2O (mean +/- 95% c.i., n = 23) and re-opening pressure was -3.15 +/- 0.51 cm H2O. Ventilation with 7% CO2 changed the closing pressure to -11.63 +/- 0.67 cm H2O (P less than 0.05) and re-opening pressure to -3.81 +/- 0.67 cm H2O (NS). In 10 animals muscle paralysis with gallamine (2 mg/kg i.v.) did not significantly alter closing or re-opening pressures during ventilation with 100% O2, and did not abolish the ability of ventilation with 7% CO2 to augment collapse resistance. In 6 animals death was followed by a fall in closing and re-opening pressures to 30-60% of the values recorded in paralysed animals. We conclude that in this preparation active muscle contraction is not the main source of resistance to airway closure or of the proclivity of the closed airway to re-open.     

Duodeno-jejunal junction dyssynergia： Description of a novel syndrome

AIM： To investigate the hypothesis that duodeno-jejunal dyssynergia existed at the duodeno-jejunal junction.
METHODS： Of 112 patients who complained of epigastric distension and discomfort after meals, we encountered nine patients in whom the duodeno-jejunal junction did not open on duodenal contraction. Seven healthy volunteers were included in the study. A condom which was inserted into the ist duodenum was filled up to 10 mL with saline in increments of 2 mL and pressure response to duodenal distension was recorded from the duodenum, duodeno-jejunal junction and the jejunum.
RESULTS： In healthy volunteers, duodenal distension with 2 and 4 mL did not produce pressure changes, while 6 and up to 10 mL distension effected significant duodenal pressure increase, duodeno-jejunal junction pressure decrease but no jejunal pressure change. In patients, resting pressure and duodeno-jejunal junction and jejunal pressure response to 2 and 4 mL duodenal distension were similar to those of healthy volunteers. Six and up to 10 mL 1^st duodenal distension produced significant duodenal and duodeno-jejunal junction pressure increase and no jejunal pressure change.
CONCLUSION： Duodeno-jejunal junction failed to open on duodenal contraction, a condition we call ＇duodenojejunal junction dyssynergia syndrome＇ which probably leads to stagnation of chyme in the duodenum and explains patients＇ manifestations.     

Biomechanical wall properties of the porcine rectum: a study using impedance planimetry.

The aim was to investigate biomechanical wall properties of the porcine rectum by way of manometry and impedance planimetry. Distension of a balloon inserted into the rectum with definite pressure steps up to 80 cm H2O was done for simultaneous recording of pressure and the balloon cross-sectional area (Bcsa). Viscoelastic wall properties were derived in terms of compliance. Besides eliciting the ascending peristaltic reflex and relaxation of the internal anal sphincter, the balloon inflation elicited a phase of rapid Bcsa increase followed by an accommodation phase of slow Bcsa increase to a steady-state Bcsa, reached within 3 min. The Bcsa increased in a nonlinear way with increasing balloon pressures with only a minimal increase from 70 to 80 cm H2O. Rectal compliance decreased in a nonlinear way with increasing distension pressure.     

Chest wall mechanics during exercise in patients with severe chronic air-flow obstruction

We studied the dynamic mechanical properties of the chest wall in 7 patients with severe chronic air-flow obstruction (CAO). Measurements were made during quiet breathing at rest and during exercise on a bicycle ergometer at work rates equivalent to 50 and 100% of their maximal work rate (Wmax). The peak inspiratory pleural pressure relative to the chest wall relaxation curve (Pmus) increased from 13.5 +/- 1.5 cm H2O at rest to 22.4 +/- 1.7 cm H2O at Wmax, while the coincident transdiaphragmatic pressure increased from 9.7 +/- 2.1 cm H2O at rest to 16.5 +/- 2.3 cm H2O at Wmax. Consequently, the coincident gastric pressure relative to its value during relaxation (Pab) was negative at rest (-4.5 +/- 1.7 cm H2O) and became even more negative (-6.3 +/- 2.3 cm H2O) at Wmax. Yet the increase in ventilation with increasing exercise was associated with an increase in the passive outward displacement of the abdomen (delta Vab) relative to the total volume change (delta Vab + delta Vrc), such that the ration delta Vab/(delta Vab + delta Vrc) increased from 0.37 +/- 0.08 at rest to 0.52 +/- 0.05 at Wmax. There was no respiratory paradox. From the analysis of volume-pressure tracings of the chest wall compartments we inferred that expiratory intercostal and abdominal muscles contracted forcefully during expiration on exercise, resulting in a marked increase in pleural pressure and a change in thoraco-abdominal configuration. This represented the storage of elastic and gravitational energy, which was released during inspiration, contributing to inspiratory pleural pressures and the enhanced inspiratory flow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Propranolol blocks ventricular refractory period changes with orthostatic stress in humans

The purpose of this study was to test the hypothesis that orthostatic stress shortens the right ventricular effective refractory period by reflex activation of beta-adrenergic receptors. Twelve patients undergoing electrophysiologic testing for standard clinical indications were studied. After a full electrophysiologic study, patients underwent graded lower body negative pressure before and after administration of either propranolol (0.2 mg/kg intravenously) in Group I or atropine (0.035 mg/kg intravenously) in Group II. Before the addition of drugs, lower body negative pressure produced decreases in systolic blood pressure and significant increases in sinus rate. The effective refractory period shortened from 214 +/- 8 (mean +/- SEM) to 206 +/- 7 ms at -40 cm H2O and to 197 +/- 4 ms at -60 cm H2O lower body negative pressure. After propranolol, Group I patients had no change in right ventricular effective refractory period despite similar changes in sinus rate and systolic blood pressure. In group II patients, atropine did not alter effective refractory period responses to lower body negative pressure. Thus, reflex adjustments to orthostatic stress result in shortening of right ventricular effective refractory period mediated by way of beta-adrenergic mechanisms. These findings constitute the first evidence that sympathetic influences mobilized by the body can directly modulate ventricular electrophysiologic changes.     

持续气道正压通气对急性心源性肺水肿犬呼吸及循环功能的影响

目的研究持续气道正压(CPAP)通气对急性心源性肺水肿(ACPE)犬呼吸及循环功能的影响。方法分别监测10条犬健康状态及ACPE发生后自主呼吸、5cmH2O(1cmH2O=0.098kPa)、10cmH2O、15cmH2OCPAP时的胸腔负压(Pt)、中心静脉压(CVP)、心输出量(CO)、平均动脉压(BPm)、肺动脉楔压(PAWP)。结果与健康状态相比,ACPE犬呼吸增强、增快,Pt由-(4.90±0.09)cmH2O上升至-(10.90±0.75)cmH2O,CVP由(10.1±0.4)mmHg下降至(8.0±0.7)mmHg,CO由(1.52±0.13)L/min下降至(0.85±0.09)L/min,PAWP升高(P均<0.05)。CVP与Pt变化呈正相关(r=0.78,P<0.01)。5及10cmH2OCPAP时Pt值恢复至-(6.53±0.11)cmH2O和-(5.14±0.25)cmH2O,呼吸形式基本恢复正常,CVP升至(11.6±0.7)mmHg和(14.2±0.2)mmHg,CO增加至(1.45±0.11)L/min和(1.24±0.11)L/min,其中5cmH2OCPAP组PAWP下降(P均<0.05)。15cmH2OCPAP时,呼吸浅快,Pt为-(0.82±0.37)cmH2O,CO为(0.82±0.07)L/min,其他血流动力学指标皆恶化(P均<0.05)。结论犬ACPE发生时,呼吸运动显著增强,Pt升高,并导致CVP和CO的下降;适当CPAP通过改善呼吸功能,调节Pt改善ACPE犬的心功能。     

Functional activity of the rectum： A conduit organ or a storage organ or both？

AIM: To investigate whether the degree of rectal distension could define the rectum functions as a conduit or reservoir. METHODS: Response of the rectal and anal pressure to 2 types of rectal balloon distension, rapid voluminous and slow gradual distention, was recorded in 21 healthy volunteers (12 men, 9 women, age 41.7±10.6 years). The test was repeated with sphincteric squeeze on urgent sensation. RESULTS: Rapid voluminous rectal distension resulted in a significant rectal pressure increase (P < 0.001), an anal pressure decline (P < 0.05) and balloon expulsion. The subjects felt urgent sensation but did not feel the 1st rectal sensation. On urgent sensation, anal squeeze caused a significant rectal pressure decrease (P < 0.001) and urgency disappearance. Slow incremental rectal filling drew a rectometrogram with a "tone" limb representing a gradual rectal pressure increase during rectal filling, and an "evacuation limb" representing a sharp pressure increase during balloon expulsion. The curve recorded both the 1st rectal sensation and the urgent sensation. CONCLUSION: The rectum has apparently two functions: transportation (conduit) and storage, both depending on the degree of rectal filling. If the fecal material received by the rectum is small, it is stored in the rectum until a big volume is reached that can affect a degree of rectal distension sufficient to initiate the defecation reflex. Large volume rectal distension evokes directly the rectoanal inhibitory reflex with a resulting defecation.     

慢性阻塞性肺疾病患者机械通气时对外源性呼气末正压的生理学反应

目的研究慢性阻塞性肺疾病（COPD）患者机械通气时对外源性呼气末正压的生理学反应规律，揭示反应个体化特点。方法随机选取2005年1月至2006年6月由急诊室收入我院呼吸科重症监护室的COPD急性加重期患者15例，仰卧位经口气管插管后接Evita 4呼吸机（德国Draeger公司），采用容量控制通气对受试者序贯给予相当于内源性呼气末正压水平20％、40％、60％、80％、100％、120％的外源性呼气末正压，每次给予外源性呼气末正压后均测量气道阻力、呼吸系统顺应性、气道平台压、总呼气末正压水平。根据施加外源性呼气末正压后患者气道平台压的变化，将15例患者分为正常反应组（11例），反常反应组（4例），对两组间各参数进行比较。结果15例患者当外源性呼气末正压为80％、内源性呼气末正压为100％水平时的气道阻力分别为（18．5±2．0）cmH2O·L^-1·s^-1（1cmH2O=0．098kPa）、（18．0±2．2）cmH2O·L^-1·s^-1，与外源性呼气末正压为0时的气道阻力[（23．0±2．9）cmH2O·L^-1·s^-1]比较差异有统计学意义（t值分别为5．36、6．27，P均〈0．01）；当外源性呼气末正压为120％内源性呼气末正压水平时，气道阻力和总呼气末正压水平分别为（17．3±2．1）cmH2O·L^-1·s^-1、（12．7±2．2）cmH2O，与外源性呼气末正压为0时[（23．0±2．9）cmH2O·L^-1·s^-1、（10．0±1．1）cmH2O]比较差异有统计学意义（t值分别为6．79、-3．90，P均〈0．01）。正常反应组患者基础生理学参数（外源性呼气末正压为0时）内源性呼气末正压水平、气道阻力、呼吸系统顺应性、气道平台压分别为（10．0±1．0）cmH2O、（22．8±1．9）cmH2O·L^-1·s^-1、（39±6）ml／cmH2O、（20±4）cmH2O，与反常反应组[（10．0±1．4）cmH2O、（23．1±4．1）cmH2O·L^-1·s^-1、（42±9）ml／cmH2O、（21±3）cmH2O]比较差异无统计学意义（t值分别为0．03、0．10、0．60、0．15，P均〉0．05）；正常反应组患者在外源性呼气末正压分别为40％、80％、100％、120％内源性呼气末正压时，△Ppla140，△Pplat80，△Pplat100，△Pplat120分别为（-0．020±0．970）cmH2O、（1．6±1．0）cmH2O、（4．0±2．9）cmH2O、（6．4±3．3）cmH2O，与反常反应组[（-7．500±0．920）cmH2O、（-4．4±1．4）cmH2O、（-3．8±1．9）cmH2O、（-1．6±1．2）cmH2O]比较差异有统计学意义（t值分别为-9．64、-5．90、-3．80、-3．92，P均〈0．01）。结论提示部分无自主呼吸的被动机械通气患者应用外源性呼气末正压是有益的，可以使患者气道平台压显著下降。