Biomedical subjects

M A Christensen

Publications and source records attributed to M A Christensen.

At least 37 records · Page 2Linked to original sources

PubMed1995

Simultaneous dynamic proctography and peritoneography for pelvic floor disorders.

PURPOSE: We sought to evaluate a new diagnostic technique for the identification of rectal and pelvic floor pathology in patients with obstructed defecation, pelvic fullness/prolapse, and/or chronic intermittent pelvic floor pain. METHODS: Thirteen symptomatic women with either a nondiagnostic physical examination or nondiagnostic dynamic proctography (DPG) were studied. After placement of intraperitoneal and intrarectal contrast material, resting and straining pelvic x-rays were obtained in all patients, and defecation was videotaped using fluoroscopy. RESULTS: Simultaneous DPG and peritoneography identified clinically suspected and unsuspected enteroceles in 10 of the 13 patients studied. An enterocele or other pelvic floor hernia was ruled out by the technique in three of the women studied. Rectoceles and rectal prolapse that were identified during physical examination were confirmed by DPG with peritoneography. Simultaneous DPG and peritoneography also gave a qualitative assessment of the severity and clinical significance of the identified pelvic floor disorders. Results of simultaneous DPG and peritoneography affected operative treatment planning in 85 percent of patients studied. CONCLUSION: Simultaneous DPG and peritoneography identifies both rectal and pelvic floor pathology and provides a qualitative assessment of pelvic floor pathology severity, which allows for better treatment planning in selected patients with obstructed defecation and pelvic prolapse.

Adult↗

PubMed1995

Patterns of male fecal incontinence.

PURPOSE: This study sought to identify clinical and manometric characteristics of male fecal incontinence. METHOD: Clinical charts of 25 men with a chief complaint of fecal incontinence were retrospectively reviewed. Their anorectal physiology test results were compared with those from a group of 20 healthy men. RESULTS: Fourteen men (56 percent) were "leakers," who complained of loss of liquid or solid stool smears that stained their underclothes. Eleven men (44 percent) had true incontinence, with loss of control over gas, liquid, and/or solid stool. Leakers had lower anal sphincter pressures than normal men (P < 0.05) but higher pressures than incontinent men (P < 0.05). In leakers the anal sphincter length at rest was longer than in incontinent (P < 0.01) and normal men (P < 0.05). All incontinent men had decreased manometric pressures, abnormal anorectal sensation or prolonged pudendal nerve terminal motor latencies, whereas only one-half of the leakers had physiologic abnormalities. Treatment using dietary manipulation, constipating agents or cleansing enemas was successful in nearly 90 percent of incontinent men but only 55 percent of the leakers. CONCLUSIONS: Whereas true incontinence in men is caused by a short, low pressure sphincter with altered sensation or innervation, leakage is associated with a long, intermediate pressure sphincter that frequently has normal sensation and innervation. This long, intermediate pressure sphincter may predispose these men to leakage. Treatment of leakers is less successful than treatment of incontinent men. Leakers and incontinent men have unique clinical and physiologic profiles that should be identified to help guide treatment and determine prognosis.

Adult↗

PubMed1995

Preoperative chemoradiation downstages locally advanced ultrasound-staged rectal cancer.

BACKGROUND: This prospective study assessed the effect of preoperative radiation and chemotherapy on the pathologic staging of advanced rectal cancer. METHODS: Twenty patients with rectal cancer were treated with combined chemoradiation prior to operation, after pretreatment staging of all lesions with transrectal ultrasound (TRUS). Perirectal fat invasion served as minimal criteria for preoperative neoadjuvant therapy. The pretreatment stage of these rectal lesions as defined by TRUS was then compared with the pathological stage of the surgical specimen following resection. Cancers were treated with high-dose radiation (45 to 54 Gy) in 19 of 20 patients. One patient received in excess of 60 Gy because of tumor characteristics. Chemotherapy consisted of 5-fluorouracil delivered as a continuous infusion or bolus therapy. Four to 8 weeks after neoadjuvant therapy, 13 abdominal perineal resections, 5 low anterior resections, and 2 completion proctectomies were performed. RESULTS: Following resection, rectal cancer was downstaged in 14 of 20 patients. No tumor was present in the rectal wall in 8 of 20 patients. Complete pathological response was present in 7 of 20 patients. Local recurrence occurred in 2 of 20 patients. Disease-free survival in the remaining 17 of 20 patients ranges from 9 to 51 months (average 26). CONCLUSIONS: Preoperative chemoradiation in the surgical management of advanced rectal cancer results in demonstrable tumor downstaging.

Adult↗

PubMed1995

Comparing arterial and end-tidal carbon dioxide values in hyperventilated neurosurgical patients.

BACKGROUND: Hyperventilation is a frequently used method for inducing hypercarbia in neurosurgical patients. This practice requires careful carbon dioxide monitoring that might be replaced by a less expensive and less invasive alternative to arterial blood gas monitoring. OBJECTIVE: To determine the accuracy of end-tidal carbon dioxide monitoring in hyperventilated neurosurgical patients. METHODS: Nineteen adult patients requiring hyperventilation for the reduction of intracranial pressure following head injury or neurosurgery were enrolled from the surgical intensive care unit of a level I trauma center. A correlation design was used to compare arterial carbon dioxide tensions and end-tidal carbon dioxide measurements during specific periods; secondary analysis with bias and precision estimates was performed. Also, changes in arterial carbon dioxide tensions were compared with simultaneous changes in end-tidal carbon dioxide values. RESULTS: End-tidal carbon dioxide values showed a moderately acceptable correlation with arterial blood gas measurements. However, changes in end-tidal carbon dioxide values failed to correlate with simultaneous changes in arterial carbon dioxide tension measures. Bias and precision measures confirmed these findings. CONCLUSION: In this patient sample, changes in end-tidal carbon dioxide values did not accurately reflect changes in arterial carbon dioxide tension levels in the intensive care setting. Further technological advances in noninvasive carbon dioxide monitoring may lead to a significant cost savings over traditional arterial blood gas analysis.

Adult↗

PubMed1994

Colonic anastomoses: bursting strength after corticosteroid treatment.

PURPOSE: This study was designed to determine the effect of corticosteroids on healing colonic anastomoses. METHODS: Bursting pressure measurements were performed on 108 male albino rats receiving corticosteroid treatment. Twelve animals were sacrificed at time zero to determine the bursting pressure of nonoperated, nonsteroid-treated colon. The remaining 96 animals underwent division and reanastomosis of their midtransverse colon. They were then separated into four groups of 24 each. Twelve animals in each group received steroid treatment while the remaining 12 acted as controls. The groups were sacrificed at 4, 6, 8, and 20 days. The bursting pressures of the anastomoses were then noted. RESULTS: There was no significant difference in bursting strength between treated animals and controls at four days (P = 0.27). A significant difference occurred at 6, 8, and 20 days (P = 0.01, 0.003, 0.009, respectively). The colonic bursting pressure of operated controls returned to that of a normal, nonoperated colon by 20 days. CONCLUSION: This study demonstrates that steroids do have an adverse effect on colonic anastomotic healing.

Adrenal Cortex Hormones↗

PubMed1994

Positron emission tomography for preoperative staging of colorectal carcinoma.

PURPOSE: Positron emission tomography (PET) is an imaging technique based on in vivo cellular metabolism. Increased glucose metabolism in neoplastic cells is detected by using fluorine-18 deoxyglucose. In an ongoing pilot study to determine the usefulness of this technique, PET is compared with computerized tomography (CT) for the preoperative staging of colorectal carcinoma. METHODS: Sixteen patients were evaluated with both PET and CT of the abdomen and pelvis. Results were compared with operative and histopathologic findings. Fifteen malignant lesions were found in 16 patients by histology. PET had a positive predictive value of 93 percent and a negative predictive value of 50 percent. By comparison CT had a positive predictive value of 100 percent and a negative predictive value of 27 percent. CONCLUSIONS: These preliminary results indicate that PET has increased sensitivity for staging colorectal carcinoma, whereas CT has higher specificity. The predictive value of a positive PET compares favorably with CT. Furthermore, the predictive accuracy for detection of colorectal carcinoma is 83 percent for PET and 56 percent for CT.

Adult↗

PubMed1994

Transanal ultrasound and manometry in the evaluation of fecal incontinence.

PURPOSE: This preliminary study was undertaken to clarify the role of ultrasonography of anal sphincters in the colorectal laboratory. METHODS: Twenty-eight parous female patients with fecal incontinence were evaluated with transanal ultrasonography (TAUS), anal manometry, and pudendal nerve terminal motor latency (PNTML). Ultrasound images were recorded and labeled in centimeters from the anal verge. The continuity of the internal anal sphincter (IAS) was identified as either intact or disrupted. The separation of the external anal sphincter (EAS) was measured at the 1.5-cm level and below. TAUS findings were then compared with anal manometric pressures. Clinical data were obtained by patient interview and examination during TAUS. RESULTS: Evidence of IAS disruption was associated with significantly decreased mean maximum resting pressures (P = 0.023). EAS separation was inversely proportional to mean maximum squeezing pressures (r = -0.61). In the group of patients offered sphincteroplasty, the IAS was disrupted more often (P = 0.016), mean maximum resting pressures were significantly lower (P = 0.023), mean EAS separation was significantly greater (P = 0.022), and mean PNTML was significantly faster (P = 0.004). Twenty-five percent of patients with normal clinical examinations had significant muscular injury by TAUS requiring sphincteroplasty. CONCLUSIONS: Manometric findings correlate significantly with anal sphincter defects visualized by TAUS. TAUS is useful in the evaluation and management of patients with fecal incontinence.

Adult↗

PubMed1993

Regional cerebral blood flow following hypothermic circulatory arrest in newborn dogs.

A model of hypothermic circulatory arrest has been developed in newborn dogs which simulates the procedure used for the operative repair of congenital cardiac defects in human infants. Hypothermic circulatory arrest for 1.0 h causes no brain damage, whereas cardiac arrest for 1.75 h results in damage of the cerebral cortex, basal ganglia and to a lesser extent the claustrum and amygdaloid nucleus. In the present study, we determined regional cerebral blood flow (rCBF) during 24 h of recovery from hypothermic circulatory arrest. Newborn nitrous oxide anesthetized and artificially ventilated dogs were cooled to 20 degrees C and subjected to cardiac arrest by the i.v. injection of KCl for either 1.0 or 1.75 h. Thereafter, animals were resuscitated, rewarmed to 37 degrees C, and rCBF measured with [14C]iodoantipyrine at either 2 or 18 h of recovery. Control animals were rendered hypothermic to 20 degrees C without cardiac arrest for 1.0 or 1.75 h prior to rewarming. No alterations in CBF at either 2 or 18 h of recovery were present in any of 16 analyzed structures in animals previously subjected to hypothermic circulatory arrest compared to controls rendered hypothermic alone. A direct linear correlation existed between mean arterial blood pressure and blood flow within frontal, parietal and occipital cortex, occipital white matter, hypothalamus and cerebellar vermis in puppies arrested for 1.75 h and recovered for 2 h, suggesting a loss of CBF autoregulation at this interval. No such association between blood pressure and CBF was apparent at 18 h of recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Fiber pathways and positional changes in efferent perikarya of 2.5- to 7-day chick embryos as revealed with DiI and dextran amines.

The differentiation of facial motoneurons and inner ear (octaval) efferents was examined in chicken embryos by applying DiI or dextran amines to the cut VII/VIII nerve (peripheral label) or to the basal/floor plate of rhombomeres 4/5 (central label). Central labeling found axons of these efferent neurons to leave the brain as early as 2.5 days of incubation. Peripheral labeling identified cell bodies ipsilaterally in rhombomeres 4 and 5 at 2.5 days. Central labeling at 3.5 days showed these fibers to have fully segregated into separate pathways to the facial nerve and the inner ear and that the octaval efferent axons had reached the otocyst wall. By 3.5 days many peripherally labeled octaval efferent somata were found in the floor plate and by 5 days they were found bilaterally. At 6 days, selective peripheral labeling of either the VIIth or VIIIth nerve showed that the contralateral population consisted of octaval efferents and central label applied to the floor plate of rhombomeres 4/5 identified fibers that entered the octaval nerve via the facial root and entered the vestibular sensory epithelia. Together these data suggest an initial mingling of two different motoneuron populations (facial and octaval) in rhombomeres 4/5 and a subsequent segregation by differential migration. Our data also find a much earlier arrival of octaval efferent axons at the otic vesicle than previously described and suggest a contralateral migration of many octaval efferents beginning shortly after their axons reach the facial nerve root.

Animals↗

PubMed1993

Effect of prostaglandin E1 and steroid on healing colonic anastomoses.

PURPOSE: The effect of prostaglandin E1 (PGE1) and corticosteroids alone and in combination were studied in the healing rat colon to determine whether PGE1 could not only improve healing but reverse the negative effect of steroids on colonic wound healing. METHODS: Colonic anastomoses were performed in 144 male Sprague-Dawley rats divided into four groups. The control group (I) received no further treatment. The steroid group (II) received cortisone acetate (5 mg/kg/day) beginning six days preoperatively and continuing until sacrifice. The PGE1 group (III) received 2 micrograms of PGE1 intra-aortically at surgery and for three days postoperatively. The combination PGE1/steroid group (IV) received both drugs in the same doses as those in Groups II and III. Animals were sacrificed on postoperative days 6, 10, and 14. Wound healing was evaluated by hydroxyproline content, bursting pressures, and histology. RESULTS: The hydroxyproline assay at day 10 revealed that steroid-treated rats have significantly lower levels than any other group. The PGE1 group (III) had the highest level of significance in comparison to the steroid group (II) (P = 0.001). The addition of PGE1 to steroid (Group IV) appeared to abolish the negative effect of the steroid as measured by hydroxyproline content on day 10 (P = 0.038). When measuring bursting pressures, the PGE1 group (III) had significantly higher pressures than any other group at day 10. However, no amelioration of the steroid effect on bursting pressures was seen. Histologic evaluation of the anastomosis did not reveal any significant differences among the four groups. CONCLUSIONS: PGE1 reverses the negative effect of the steroid on hydroxyproline levels at day 10. Furthermore, using bursting pressure as a parameter of wound healing, administration of PGE1 results in significantly improved anastomotic healing at day 10.

Alprostadil↗

PubMed1993

Cumulative incidence of metachronous colorectal cancer.

The incidence of metachronous colorectal cancer has most often been reported as a crude rate: second cancers/index cancers. The reported incidence varies between 0.5 percent and 3.6 percent. However, these calculations do not take into account factors such as length of survival and length of follow-up. The cumulative incidence more accurately reflects the risk for developing a metachronous cancer and was determined in a retrospective analysis of 5,476 patients who were diagnosed with colon or rectal cancer between 1965 and 1985. The cumulative probability was calculated by determining the number of patients developing a metachronous colon cancer vs. the number remaining at risk at that point in time. The calculated annual incidence for metachronous tumors was 0.35 percent per year. The cumulative incidence at 18 years was 6.3 percent. Analysis also demonstrated that metachronous cancers were diagnosed at earlier stages than were index cancers (P = 0.03). Subgroup analysis was performed on patients diagnosed with metachronous cancer before and after 1980. There was a difference in the incidence of metachronous cancers between these two groups (P = 0.04).

Adult↗

PubMed1993

Transrectal ultrasound of rectal tumors.

Since preoperative staging of rectal tumors is important in planning treatment, we evaluated transrectal ultrasound (TRUS) staging of rectal neoplasms. In 35 consecutive rectal tumors, we compared TRUS staging results with final pathologic staging. TRUS predicted the degree of tumor invasion in 19 of 24 patients (79%) and the presence or absence of lymph node metastasis in 11 of 15 patients (73%). TRUS overestimated the degree of tumor invasion in four patients (17%) and underestimated invasion in one patient (4%). The depth of tumor invasion was correctly predicted in all 14 tumors located within 6 cm from the anal verge, but, beyond 6 cm, only 5 of 10 tumors (50%) were staged correctly (p = 0.005). In the group of 11 patients who underwent preoperative radiotherapy, pretreatment TRUS predicted the depth of tumor invasion in only six patients (55%) and overestimated tumor invasion in five patients (45%), suggesting that nearly half of these tumors were downstaged by radiotherapy. TRUS accurately predicts the degree of tumor invasion, especially in tumors closer to the anal verge, allowing for better treatment planning in patients with low to middle rectal neoplasms.

Adult↗

PubMed1993

Myocardial contusion: new concepts in diagnosis and management.

Myocardial contusion is diagnosed with one or a combination of four diagnostic procedures: electrocardiography, echocardiography, creatine kinase MB fractions and/or radionuclide procedures. This article presents a critical review of 18 recent studies addressing the utility, sensitivity and specificity of these tests. Careful review suggests that clinically significant myocardial contusions as a result of blunt trauma are rare and may be detected simply and inexpensively using electrocardiography and careful physical examination. Serum myocardial enzymes and radionuclide studies are nonspecific and are not predictive of cardiac complications. Echocardiography is useful in the management of myocardial decompensation but not as a primary screening tool in blunt cardiac injury. Cost comparisons, resource allocation and implications for critical care practice are discussed.

Adolescent↗

PubMed1992

Rare pelvic floor hernias. Report of a case and review of the literature.

The case of a 64-year-old female who presented with difficult evacuation of stool is reported. A posterior perineal hernia was diagnosed by dynamic proctography. The patient had an unusual herniation of the upper rectum through the perineal defect. At surgery, there was no peritoneal sac, since the herniation occurred extraperitoneally. The patient was treated with repair of the pelvic floor using Marlex mesh and rectopexy. Pelvic floor hernias are rare and often difficult to diagnose. The three types, in order of decreasing frequency, are obturator, perineal, and sciatic. The etiology, diagnosis, and treatment of each is discussed.

Buttocks↗

PubMed1992

"House" advancement pedicle flap for anal stenosis.

Long strictures of the anal canal, extending from the dentate line to the perianal skin, have challenged surgeons for many years. Numerous techniques have been devised to treat anal strictures. A technique to relieve an anal stenosis that involves the entire circumference and the length of the anal canal from the dentate line onto the perianal skin is described. It has two principal advantages: 1) it provides a broad skin flap for the entire length of the involved anal canal; and 2) it provides primary closure of the donor site. In addition, it avoids extensive mobilization of tissue, the flap maintains good blood supply with minimal tension, and there is no small tip prone to necrosis.

Anal Canal↗

PubMed1992

Normal variation in anorectal manometry.

A study was performed to define the normal range of values for anorectal manometry. Normal volunteers were divided according to gender and parity. There were 20 males, 21 nulliparous females, and 18 multiparous females among the 59 subjects. Anorectal manometry using a radial eight-port catheter was performed during resting and squeezing maneuvers of the anal sphincter. Computerized data analysis and three-dimensional imaging were used to calculate sphincter length at rest and squeeze, mean maximum resting and squeeze pressures, and vector symmetry index. The sphincter length at rest and with squeezing in males was significantly greater compared with the two female groups (P < 0.007). Mean maximum squeeze pressures were also significantly elevated in the male group compared with the female groups (P = 0). Mean maximum resting pressures were significantly higher in nulliparous women than in multiparous women (P = 0.04). However, no difference in resting pressures was found between males and nulliparous females. A comparison of the symmetry of the anal canal revealed no differences among the three groups. Ranges for normal anorectal manometry are definable. Normal ranges are distinct for subgroups of patients, particularly with regard to gender and parity. Patients must be compared with their normal subgroups to correctly identify manometric abnormalities.

Adult↗

PubMed1990

Increased expression of the retinoblastoma gene in human colorectal carcinomas relative to normal colonic mucosa.

We report the first evidence of increased levels of the retinoblastoma (Rb) message in a majority of colorectal cancers when compared with normal mucosa. Southern blot analysis showed an increase in Rb gene copy number in at least 28% of colorectal carcinomas relative to normal mucosa. These results plus previous reports of nonrandom chromosome 13 gains in approximately 50% of colorectal cancers suggest that an increase in Rb gene copy number occurs frequently in these tumors. Possible mechanisms pertaining to overexpression of the Rb gene are discussed in relation to its role as a recessive cancer gene.

Blotting, Northern↗

PubMed1990

Manometric diagnosis of anal sphincter injuries.

A manometric technique of anal pressure vectography has been developed for the detection of anal sphincter injuries. Manometric symmetry of the anal sphincter can be visualized on the pressure vectorgram and quantified as a vector symmetry index. The mean vector symmetry index in asymptomatic women was 0.76, compared with 0.33 in incontinent women with a known sphincter injury (p = 0.0001). Among women who were incontinent without having a recognized sphincter injury, nearly half of those who had a previous episiotomy had subnormal (less than 0.60) vector symmetry indices (p = 0.0003). The values were in the same range as those from known injuries, suggesting the presence of an occult sphincter injury. In contrast, normal symmetry indices were found in all those who had never had an episiotomy or who presented with outlet constipation. We conclude that the vector symmetry index can expose occult anal sphincter injuries and may have a role in the selection of patients for sphincter repair.

Adolescent↗