Urinary Bladder Pressure Research Articles

Incidence and clinical pattern of the abdominal compartment syndrome after "damage-control" laparotomy in 311 patients with severe abdominal and/or pelvic trauma.

To investigate the incidence, main physiologic effects, and therapeutic management of the abdominal compartment syndrome (ACS) after severe abdominal and/or pelvic trauma. Retrospective analysis from January 1991 to December 1996; prospective study from January 1997 to August 1998. Level I trauma center, intensive care unit. A total of 311 patients with severe abdominal and/or pelvic trauma and "damage-control" laparotomy on day of admission. The ACS was defined as the development of significant respiratory compromise, including elevated inspiratory pressure of >35 mbar, a decreased Horowitz quotient (<150 torr [<20 kPa]), renal dysfunction (urine output, <30 mL/hr), hemodynamic instability necessitating catecholamines, and a rigid or tense abdomen. Beginning with January 1997, urinary bladder pressure as an additional variable for the diagnosis of ACS was continuously measured in patients (n = 12) at risk. Bladder pressures of >25 mm Hg indicated ACS. Seventeen patients (5.5%) developed ACS because of persistent intra-abdominal/retroperitoneal bleeding (n = 12; 70.6%) or visceral edema (n = 5; 29.4%). All patients with ACS underwent primary fascial closure. In eight of these patients (47%), abdominal and/or pelvic packing for hemostasis was performed. All patients with ACS required decompressive emergency laparotomies because of physiologic derangements. The time between primary laparotomy and decompressive laparotomy was 12.9 +/- 2.0 hrs. Emergency decompression of the abdomen resulted in a significant increase in the cardiac index (+146%), tidal volume (+133%), Horowitz quotient (+156%), and urine output (+1557%), whereas bladder pressure (-63%), heart rate (-19%), central venous pressure (-30%), pulmonary artery occlusion pressure (-43%), peak airway pressure (-31%), partial pressure arterial carbon dioxide (-30%), and lactate (-40%) markedly (p < .05) decreased. In two multiply injured patients with additional head trauma, ACS caused a critical increase of the intracranial pressure, which markedly dropped after the release of abdominal tension. Risk factors for the occurrence of ACS are severe abdominal and/or pelvic trauma, which require laparotomy and packing for the control of hemorrhage. The ACS occurs within hours and causes life-threatening physiologic derangements and a critical rise in intracranial pressure in patients with combined abdominal/pelvic and head trauma. Decompressive laparotomy immediately restores impaired organ functions. In patients at risk, the continuous measurement of urinary bladder pressure as a simple, noninvasive, and less expensive diagnostic tool for early detection of elevated intra-abdominal pressure is mandatory.

Magnetic stimulation: a novel method for inducing evacuation of the neuropathic rectum and urinary bladder in a canine model

Objectives. To study the effect of sacral magnetic stimulation (MS) on the neuropathic rectum and urinary bladder in dogs. It has been demonstrated in a canine model and in humans that sacral MS of both the empty and full rectum effected a significant increase in rectal and vesical pressures. Evacuation of the full rectum, as well as balloon expulsion, were achieved. Methods. In 15 dogs, bilateral pelvic ganglionectomy was carried out, and rectal and vesical denervation was confirmed by bethanechol and atropine testing. Sacral MS of the empty and full rectum and urinary bladder were performed by means of a magnetic stimulator and coil. The electromyographic (EMG) response of the rectus abdominus muscles to sacral MS was recorded. Results. After pelvic ganglionectomy, the rectal, vesical, anal, and urethral pressures revealed a significant decrease (all P <0.05). On sacral MS of the empty rectum and urinary bladder, rectal and vesical pressures increased (both P <0.001) and anal and urethral pressures did not change (both P >0.05). Atropine injection abolished the rectal and vesical response to sacral MS; bethanechol did not. During sacral MS, no EMG activity of the rectus abdominus muscles was recorded. Intermittent sacral MS of the full rectum and urinary bladder raised rectal and vesical pressures (both P <0.001) and effected evacuation. Conclusions. Sacral MS causes evacuation of the neuropathic rectum and urinary bladder in a canine model. The technique is simple, noninvasive, nonradiologic, and cost-effective and has no adverse effects. It is suggested that it be used for evacuation of the neuropathic rectum and urinary bladder in patients with spinal cord injury.

Multisystem organ failure secondary to increased intraabdominal pressure.

Acutely increased intraabdominal pressure can lead to multisystem organ dysfunction. Organ dysfunction consists of acute pulmonary failure secondary to compressive atelectasis and associated with high peak inspiratory pressures and impaired gas exchange, acute renal failure with marked oliguria without hypernaturia, intestinal and hepatic ischemia possibly leading to bacterial translocation or necrosis with peritonitis, increased intracranial pressures which may cause brain dysfunction or aggravate head injury edema, venous thrombosis and thromboembolism, and abdominal wall ischemia or necrosis. The diagnosis is made clinically in a patient with high peak inspiratory pressures, oliguria and an apparently tight abdomen, although urinary bladder pressure > or = 20 cm H2O pressure is suggestive. However, chronically increased intraabdominal pressure as is seen in the morbidly obese, pregnancy and cirrhosis may be misleading. As to treatment, once the diagnosis is made, the patient's abdomen should be opened and the tension relieved. The intestinal contents need to be protected and evaporative water loss minimized by either closing the skin and not the fascia or, if this is not possible, using an impermeable protective dressing. If the abdomen is difficult to close at the primary operation, it is best to prevent the development of an acute abdominal compartment syndrome by closing only the skin or leaving it open and using an impermeable dressing. In conclusion, the acute abdominal compartment syndrome has become increasingly recognized as a cause for multisystem organ failure. Recognition of the problem or prevention is mandatory for optimal patient survival.

Simultaneous arterial and urinary bladder pressure recordings in multiple system atrophy and in spinal disorders with detrusor hyperreflexia.

Simultaneous arterial and urinary bladder pressure measurements were recorded during bladder filling in 21 patients with urinary bladder symptoms; seven patients had autonomic failure due to multiple system atrophy (MSA), seven had spinal cord disease of different aetiology with detrusor hyperreflexia (DH) and seven had no neurological abnormalities. A significant increase in average systolic blood pressure (BP) was recorded on bladder filling in the neurologically intact patients (from 110 to 137 mmHg) and in the patients with spinal cord disease and DH (from 109 to 129 mmHg). In those with MSA, the BP rose in four and fell in three patients. The vesicopressor response during cold receptor-mediated DH was not significantly higher when compared with room-temperature saline and when compared with the BP response during bladder filling in the neurologically intact patients. Finally, intravesical lignocaine retained in the bladder for 15 min did not influence the BP response to cold receptor stimulation in patients with spinal cord disease and DH. These findings and their pathophysiological and clinical implications are discussed.

Increased intra-abdominal pressure and cardiac filling pressures in obesity-associated pseudotumor cerebri.

To determine whether intra-abdominal pressure (as estimated from urinary bladder pressure) is elevated in patients with central obesity (as measured by sagittal abdominal diameter) and pseudotumor cerebri and whether this increased intra-abdominal pressure is associated with increased pleural pressure and cardiac filling pressure, implying a resistance to venous return from the brain. Nonrandomized, prospective. University hospital, operating room. Intracranial pressure, urinary bladder pressure, sagittal abdominal diameter, transesophageal pleural pressure, central venous pressure, pulmonary artery pressure, and pulmonary artery occlusion pressure. Six women with pseudotumor cerebri (one with CSF leak, one with lumboperitoneal shunt). Urinary bladder pressure (22 +/- 3 cm H2O) and sagittal abdominal diameter (29 +/- 3 cm) were significantly elevated in these patients with elevated intracranial pressure (293 +/- 80 mm H2O) compared with a previously reported group of nonobese control patients. The transesophageal pleural pressure (15 +/- 10 mm Hg), central venous pressure (20 +/- 6 mm Hg), mean pulmonary artery pressure (31 +/- 6 mm Hg), and pulmonary artery occlusion pressure (21 +/- 7 mm Hg) were all markedly elevated compared with published normal values and with previous data from obese patients without pseudotumor cerebri. These data support the hypothesis that central obesity raises intra-abdominal pressure, which increases pleural pressure and cardiac filling pressure, which impede venous return from the brain, leading to increased intracranial venous pressure and increased intracranial pressure associated with pseudotumor cerebri.

Detrusor-sphincter dyssynergia induced by cold stimulation of the urinary bladder of rats.

Instillation of cold water into the urinary bladder has been used as a diagnostic test to evaluate neurogenic dysfunctions of the lower urinary tract (LUT). This study examined the effects of cold stimulation on the LUT of urethan-anesthetized rats. Urinary bladder pressure and external urethral sphincter (EUS) electromyogram (EMG) were recorded during cystometrograms in which body- or room-temperature saline was infused continuously into the bladder and voided through the urethra. Subsequent infusion of cold saline (6-8 degrees C) into the bladder increased by approximately 100% the duration and amplitude of supraspinal reflex bladder contractions, increased baseline bladder pressure, increased the pressure threshold for inducing micturition, and increased EUS EMG activity. Blocking EUS activity by transecting the pudendal nerves or by administering a neuromuscular blocking agent markedly reduced or eliminated the effect of cold stimulation. Capsaicin pretreatment suppressed the effect of cold stimulation. It is concluded that cold temperatures stimulate capsaicin-sensitive C fiber bladder afferents that reflexly activate the EUS, producing detrusor and sphincter dyssynergia and increasing urethral outlet resistance. This in turn increases the amplitude and duration of bladder contractions during voiding.

Intra-abdominal pressure, sagittal abdominal diameter and obesity comorbidity.

To determine relationship of intra-abdominal pressure to central obesity and the comorbidity of obesity. Non-randomized, prospective. University hospital, operating room. Eighty-four anaesthetized consecutive patients prior to gastric bypass for morbid obesity and five non-obese patients before colectomy for ulcerative colitis. Weight, body mass index (BMI), co-morbid history, sagittal abdominal diameter, waist:hip (W:H) ratio and urinary bladder pressure, as an estimate of intra-abdominal pressure. Urinary bladder pressure was greater in the obese than the non-obese (18 +/- 0.7 vs. 7 +/- 1.6 cm H2O, P < 0.001), correlated with sagittal abdominal diameter (r = +0.67, P < 0.001) and was greater (P < 0.05) in patients with, than those without, morbidity probably (hypoventilation, gastroesophageal reflux, venous stasis, stress incontinence, incisional hernia) or possibly (hypertension, diabetes) due to increased abdominal pressure. W:H ratio correlated with urinary bladder pressure in men (r = +0.6, P < 0.05) but not women (r = -0.3). Increased sagittal abdominal diameter was associated with increased intraabdominal pressure which contributed to obesity-related comorbidity. W:H ratio was not a reliable indicator of intra-abdominal pressure for women who often have both peripheral and central obesity. Further studies are needed to evaluate the relationship between intra-abdominal pressure and Type II diabetes and hypertension.

Expanded Followup of Intravesical Oxybutynin Chloride Use in Children with Neurogenic Bladder

We evaluated the long-term results of intravesical oxybutynin chloride use in children with neurogenic bladders who could not tolerate or whose conditions were refractory to oral therapy. We reviewed our experience with 28 children (myelomeningocele in 27 and imperforate anus in 1) who presented with urinary incontinence and/or elevated bladder pressures refractory to intermittent catheterization and oral anticholinergic medication. Intravesical oxybutynin was administered to each child by instillation of 5 mg. crushed oxybutynin chloride in 10 cc sterile saline 2 times daily during catheterization. Seven patients (25%) could not tolerate intravesical oxybutynin secondary to anticholinergic side effects. The remaining 21 children have been followed on intravesical oxybutynin for a mean of 35 months (range 3 to 67). Of these 21 children 12 (57%) became completely dry day and night, 5 (24%) achieved daytime continence between catheterizations and 4 (19%) remained clinically unchanged with 2 in diapers. On urodynamics these 21 patients had increased bladder capacity of up to 1,150% (mean 237%, p < 0.0001) and decreased mean maximum filling pressures of -31% (p = 0.002). Although a number of patients continued to have anticholinergic side effects, a majority had significant improvement in urodynamic parameters and continence. The response appears to be durable, and it spares many of these children from undergoing bladder augmentation.

Contribution of alpha- and beta- adrenoceptors and neuropeptide-Y to autonomic dysreflexia.

Modest increases in urinary bladder pressure result in acute hypertensive episodes in humans with spinal cord lesions above T5. The underlying mechanisms of this condition, referred to as autonomic dysreflexia, are not well understood. The aim of this study was to characterize the contribution of alpha- and beta-adrenoceptors as well as circulating neuropeptide-Y (NPY) to the pressor response to bladder distension in conscious cervical spinal rats. Rats were chronically instrumented with arterial and venous catheters. After 2-3 days, a complete spinal transection (C7) was performed, and the urinary bladder was catheterized: 24 h later, mean arterial pressure (MAP) responses to 5 min bladder distensions (+40) were measured under control conditions and after administration of specific autonomic antagonists. To assess the contribution of alpha and beta adrenergic mechanisms the alpha antagonist prazosin (0.45 mg/kg i.v.) and beta antagonist, propranolol (4 mg/kg i.v.), were administered individually or together. Blood samples were taken before, during and after bladder distension for determination of plasma NPY by radioimmunoassay. The pressor response to bladder distension was approximately 30 mmHg under control conditions. The response was attenuated (-38%), but not abolished, by prazosin. A similar attenuation (-41%) was observed with propranolol. There were no changes in plasma NPY in response to bladder distension. Finally, the pressor response was completely abolished by combined alpha- and beta-adrenergic blockade. These results suggest that autonomic dysreflexia is mediated exclusively by adrenergic receptors in the spinal rat. Moreover, both alpha and beta adrenergic receptors contribute to the pressor response induced by bladder distension in the conscious cervical spinal rat.

Study of the response of the urinary bladder to stimulation of the cervix uteri and clitoris — The ‘genitovesical reflex’: An experimental study

There is a debate as to whether, during the sexual act, some women eject a fluid that could be urine. As a part of investigation into this subject, the effect of stimulation of the clitoris and cervix on urinary bladder pressure and external urethral sphincter (EUS) activity was studied in 12 bitches. The clitoris and cervix were stimulated both electrically and mechanically. Upon clitoral or cervical stimulation, the vesical pressure dropped (P<0.05) and the EMG activity of EUS increased; action potentials increased and latency decreased when the stimulation frequency increased. No fluid came out of the external urethral orifice or the vagina. Stimulation of the anesthetized clitoris and cervix effected no vesical pressure or EUS response. These results were reproducible. The study has shown that on clitoral and cervical stimulation, which closely simulates the conditions during coitus, the bladder neck was firmly closed by EUS contraction, whereas the vesical detrusor was relaxed. A constant and reproducible reflex relationship existed between the clitoris, or the cervix, and the urinary bladder, which the author calls the ‘genitovesical reflex’ and which probably acts to prevent urinary leak during coitus. The genitovesical reflex may prove to be of diagnostic significance in genitourinary disorders.

Intra-abdominal pressure measurement using a modified nasogastric tube: Description and validation of a new technique

This study assessed the accuracy of an intragastric method of measuring intra-abdominal pressure (IAP). Prospective sequential study with simultaneous paired measurement of gastric and urinary bladder pressures. Operating theatre, University Teaching Hospital. 9 patients undergoing laparoscopic cholecystectomy were studied. Intraperitoneal pressures were monitored during peritoneal insufflation at laparoscopy up to a pressure of 20 mmHg. Intra-abdominal pressure measurements were recorded simultaneously using a gastric balloon and urinary catheter. Gastric pressure may be up to 4 mmHg higher or 3 mmHg lower than urinary bladder pressure. Intra-abdominal pressure can be measured easily in this new fashion, allowing a continuous pressure trend to be obtained without interfering with urinary output estimation.

Patchplasty with expanded polytetrafluoroethylene and skinplasty for the closure of large congenital abdominal wall defects

A combined technique of patchplasty with expanded polytetrafluoroethylene (PTFE) and a special skinplasty is described for congenital abdominal wall defects where the abdominal cavity needs enlargement but skin closure is primarily possible. The patchplasty consists of suturing two half-moon-shaped, expanded PTFE leaves to the sides of the muscular abdominal wall, then approximating them under observation of intra-abdominal pressure by monitoring five parameters (urinary bladder pressure, central venous pressure, transcutaneous oxygen saturation, ventilation pressure, and mean arterial pressure). The skin is incised in a horizontal manner according to the tension lines. However, after closure, regional necrosis of the skin in the mid-portion above the incision is often observed due to lack of sufficient subcutaneous tissue at this site. Therefore, a skinplasty is done as a preventive measure, resecting this potential site of necrosis. The final appearance of the skin is an inverted T-shape. The surgical and monitoring techniques are described and illustrated.

Urinary bladder dysfunction in spontaneously diabetic Chinese hamsters

Urinary bladder dysfunction was investigated in spontaneously diabetic Chinese hamsters of the Asahikawa colony (CHAD). The wet weight of the urinary bladder was significantly increased in CHAD when compared with nondiabetic controls. In response to continuous infusion of physiological saline into the bladder under anesthesia, regular micturition was observed in controls. However, the threshold volume (i.e. the minimum volume at which rhythmic contraction appeared) was significantly increased and the amplitude of bladder contractions during micturition was decreased in CHAD aged 3–5 months (duration of diabetes, 0.6–2.2 months), leading to incomplete micturition. The frequency of micturition was also increased. Overflow incontinence was observed in all CHAD aged 13–15 months (duration of diabetes, 10–14 months). Acetylcholinesterase staining and activity in the urinary bladder walls were both significantly decreased in CHAD compared with controls. The in vitro increment of urinary bladder pressure caused by stimulation with bethanechol was not different between CHAD and controls. These findings suggest that CHAD have urinary bladder dysfunction which is caused by autonomic neuropathy and not by detrusor myopathy.

Regulation of renal pelvic pressure by diuresis and micturition

The influence of the voiding cycle and diuresis on the hydrodynamic pressures of the renal pelvis in the multicalyceal kidney of miniature pigs has been examined. Identification of the pressure patterns characteristic of the renal pelvis with an undisturbed pelviureteric and ureterovesical junction was emphasized. The frequency and amplitude of contractions in the renal pelvis were measured bilaterally. The patterns of renal pelvic pressure changes were interpreted during bladder filling and emptying and diuresis to evaluate the mechanisms facilitating the pressure isolation of the upper urinary tract. These studies were undertaken in the awake pig equipped with a long-term radiotelemetry implant transmitting renal pelvic and urinary bladder pressure. The results show that renal pelvic contractions are low-pressure events having an amplitude of 10.3 +/- 4.2 cmH2O and a frequency of 6.6 +/- 0.7 contractions/min. During basal hydration, the process of renal pelvic filling and emptying is active, with rhythmic pelvic contractions. The left and right renal pelvis demonstrate approximately equal frequency, 1.04:1.00, but are not synchronous. Furosemide-stimulated diuresis produces radical changes in the renal pelvis by transforming emptying from an active to passive mode and facilitating the transmission of voiding pressures and spontaneous bladder pressures to the kidney.

Chronic cervical spinal cord injury and autonomic hyperreflexia in rats

Although it is well established that patients with cervical spinal cord injury are prone to acute, marked, hypertensive episodes, i.e., autonomic hyperreflexia, the specific mechanisms mediating this sometimes-fatal phenomenon are not completely understood. In this report, we describe the preparation and characterization of a rat model of chronic cervical spinal cord injury and autonomic hyperreflexia. Adult male Sprague-Dawley rats were chronically instrumented with arterial, venous, and gastric catheters. Beginning the first day after a complete cervical spinal transection (CST) and continuing for 1 wk, acute hypertensive responses to a modest increase of urinary bladder pressure (0-20 mmHg) were studied. Mean arterial pressure increased 25.9 +/- 4.8 mmHg during bladder distension the first day after CST. This response was not significantly different 3, 5, and 7 days after CST (overall average = 18.0 +/- 2.3 mmHg). The pressor response to bladder distension was completely abolished by intravesical lidocaine and autonomic ganglionic blockade (atropine + hexamethonium). Responses to bladder distension were not observed after the administration of chloralose anesthesia. We conclude that after cervical spinal transection the rat exhibits autonomic hyperreflexia similar to that seen in humans with spinal injury. Furthermore, autonomic hyperreflexia is completely established within 24 h after CST in the rat. Finally, some spinal autonomic reflexes are suppressed by chloralose anesthesia in the rat.

Sensory nerves and urinary bladder function: Effects of diabetes, capsaicin and acrylamide treatment

1. 1. A comparison was made of the proposed neurotoxic effects of acrylamide, capsaicin, and diabetes on rat urinary bladder pressure responses elicited by infusion of buffer into the organ (distension). 2. 2. Treatment with capsaicin or acrylamide completely abolished the bladder pressure responses. 3. 3. After 4 weeks of diuresis equivalent to that of the diabetic model, the pressure response was markedly diminished compared to control. This response was greatly increased following l-DOPA, which augments the micturition reflex. 4. 4. After 4 weeks of streptozoticin-induced diabetes, the pressure response was slightly diminished compared to control and most closely resembled the response from the diuretic group treated with l-DOPA.

Restoration of micturition using microelectric current in experimentally induced spastic urinary bladder in rabbits

The 29 rabbits used in this study were divided into three groups, A (A 1 and A 2), B, and C. In subgroup A 1, 4 animals were used in order to verify whether the contact of an electrode to the sacral nerves results in some abnormality of voiding reflex. In subgroups A 1 and A 2 (4 animals each) we further studied the micturition function using three parameters: (i) urinary bladder fluoroscopy and radiography, (ii) cystomanometry, and (iii) electromyography of the pelvic floor muscles (external sphinter). In group B (9 rabbits) spastic paraplegia and micturition disturbances resulted from spinal cord compression that was induced by inserting a balloon catheter into the T 11–T 12 intervertebral foramen. In this group the parameters studied revealed a spastic urinary bladder in all animals. Finally, the 12 animals of group C were rendered paraplegic as described in group B, and microelectrodes were placed over the sacral nerves as in subgroup A 1. By applying a specific sequence of sacral nerve stimulation we succeeded in satisfactory urinary bladder emptying as confirmed by the micturition parameters studied: The urinary bladder pressure decreased from 65 ± 3 to 28 ± 3 mm Hg. The pelvic floor muscle amplitude was lowered from 130 ± 7 to 20 ± 3 μV, and finally the radiological bladder size also decreased from 38 cm 2 before voiding to 18 ± 3 cm 2 after voiding. These results indicate that microelectric current stimulation of the sacral nerves, when applied under a specific sequence, could rather satisfactorily restore micturition disturbances, at least in this experimental animal.

Decreased smooth muscle side effects with 16, 16-dimethyl-trans-Δ 2-PGE 1 methyl ester in Japanese monkey ( [formula omitted

The smooth muscle stimulating activity of a new PGE 1 analog, 16, 16-dimethyl-trans-Δ 2-PGE 1 methyl ester (ONO-802) was evaluated by simulataneous;y recording the EMG of the uterus and intestines, along with urinary bladder pressure, and blood pressure in pregnant and non-pregnant Japanese monkeys ( Macaca fuscata fuscata ). Single intravenous injections of ONO-802 in increasing dosages (0.2–5 μg/kg) were found to be 50–100 times or more effective in inducing uterine contraction than PGF 2 α and PGE 1. A mild, transient gastrointestinal muscle stimulating activity was observed, but change in urinary bladder pressure and blood pressure was not evident. ONO-802 induced uterine contractions in the pregnant animals were 10 times greater than in the non-pregnant animals. These results suggest that ONO-802 may be a suitable clinical prostaglandin for use in therapeutic abortion.

Changes in discharge rate of epileptogenic foci during active and passive changes in urinary bladder pressure in cats

The activity of cortical epileptogenic foci induced by focal freezing and topical administration of penicillin was monitored in cats during various phases of alterations in urinary bladder pressure produced by detrusor contractions and passive distention. The control epileptiform spike discharge rate was decreased during all phases of detrusor contractions and during the filling phase of passive distension. In contrast, the spike rate was increased during all remaining phases of passive distension. It was concluded that changes in bladder pressure can modulate the activity of cortical epileptogenic foci. It is suggested that suppression of spike rate is the result of the desynchronizing effects of afferent input related to bladder pressure changes. Motor activity related to detrusor contraction may have a similar, but lesser, effect, and may also produce the precontraction suppression. Enhancement of cortical epileptiform discharge rate may be due to a synchronizing “rebound” effect produced by a sudden reduction of high suppressive levels of afferent activity to very low or zero levels.

Cardiovascular responses to bladder distension in patients with spinal transection.

Arterial blood pressure, heart rate, and cutaneous volume pulses were recorded during controlled elevation of urinary bladder pressure in a group of seven patients with spinal cord transsection above vertebral level T5 and in another group of four patients below T5. Profound elevations in systolic blood pressure and pulse pressure were induced by bladder distension when the lesion was situated above T5. Lesser elevations occurred in patients with lesions below T5. Marked vasoconstriction characterized skin areas innervated by the "isolated" spinal cord, while passive dilatation occurred in areas supplied by the proximal cord. Only three of seven patients with lesions above T5 level had decreased heart rate during marked elevations in arterial blood pressure. The marked elevations in pulse pressure in patients with lesions above T5 could not be explained solelyby increased vasoconstriction and decreased heart rate, but involves also inotropic cardiac responses. These inotropic responses are mediated by cardiac sympathetic nerves which leave the spinal cord above the T5 level.