Trauma mannequin assessment of management skills of surgical residents after advanced trauma life support training.

BACKGROUND: We tested the effectiveness of Advanced Trauma Life Support (ATLS) training among surgical residents using a specially designed mannequin. MATERIALS AND METHODS: Thirty-two Postgraduate Year I surgical residents were randomly assigned to two groups of 16 each. By use of a trauma mannequin, the 32 residents' performances were scored using four trauma scenarios before 16 residents (ATLS group) completed a standard ATLS course. Performances were also scored after the ATLS course on another four trauma scenarios. The scores were standardized to a maximum of 20 for each scenario. Organized Approach scores with a range of 1 to 5, Priority scores ranging from 1 to 7, and global ratings of Honors, Pass, Borderline, or Fail were assigned for each clinical scenario. RESULTS: The pre-ATLS assessment scores were similar for both groups ranging between 9.4 +/- 3.5 and 11.4 +/- 2.9 for the ATLS group and between 10.2 +/- 3.8 and 11.4 +/- 3.9 for the non-ATLS group. The ATLS group scores ranged from 16.0 +/- 1.3 to 17.4 +/- 3.1 after the course and the non-ATLS group scores ranged from 11.4 +/- 4.2 to 12.9 +/- 4.0 (P < 0.05). Pre-ATLS Organized Approach scores were 2.9 +/- 1.0 and 2.7 +/- 1.1 (NS) for the ATLS and non-ATLS groups, respectively, with post-ATLS scores being significantly higher in the ATLS group (4.9 +/- 1.2 compared with 2.8 +/- 1.2 for the non-ATLS group, P < 0. 05). Initial Priority scores were also similar for both groups (3.2 +/- 1.4 for the ATLS group and 3.3 +/- 2.0 for the non-ATLS group). Post-ATLS Priority scores were significantly higher (6.4 +/- 1.4) in the ATLS group compared with 4.2 +/- 1.9 for the non-ATLS group (P < 0.05). The pre-ATLS global ratings were similar for both groups and post-ATLS there were 10 Honors ratings in the ATLS group and none for the control group. CONCLUSIONS: Using a trauma mannequin, for assessment, surgical residents completing the ATLS course demonstrated superior resuscitation skills compared with a non-ATLS group.

Impact of the prehospital trauma life support programme in Trinidad and Tobago.

The impact of the Prehospital Trauma Life Support (PHTLS) programme, introduced in Trinidad and Tobago in 1992, was assessed by questionnaires completed by 26 medical personnel (MP); 71 ambulance personnel (AP); and 50 non ambulance paramedical personnel (NAP). Of the 23 MP, 45 AP and 38 NAP who were aware of the programme, 19 (82.6%) MP, 40 (88.9%) AP and 25 (65.8%) NAP were able to differentiate personnel that had taken the PHTLS programme based on their performance. 32 (71.1%) of the AP were PHTLS trained. 24 (53.3%) and 4 (9%) of the AP identified poor equipment and poor supervision, respectively, as reasons for difficulty in applying PHTLS principles. Improvements observed among those completing the PHTLS programme were: improved resuscitation techniques by 20 (86.9%) MP, 38 (84.4%) AP and 27 (71.1%) NAP; better vital signs recording by 8 (34.8%) MP, 27 (60%) AP and 8 (21.1%) NAP; improved immobilization by 23 (100%) MP, 40 (88.9%) AP and 33 (86.8%) NAP; better haemorrhage control by 22 (95.6%) MP, 40 (88.9%) AP and 24 (63.2%) NAP; appropriate splinting of fractures by 23 (100%) MP, 40 (88.9%) AP and 32 (84.2%) NAP; and increased utilization of oxygen by 15 (65.2%) MP, 31 (68.9%) AP and 21 (55.3%) NAP. 32 (71.1%) AP with PHTLS training indicated improvement in their ability to resuscitate and transport trauma victims, with 42 (93.3%) reporting improvement in overall prehospital care. Medical, paramedical and ambulance personnel all perceive a significant positive impact of PHTLS training on prehospital trauma care. Although improvements in supervision, documentation and equipment are still required, improved trauma resuscitative techniques after PHTLS training should improve trauma patient outcome in Trinidad and Tobago.

Impact of the prehospital trauma life support programme in Trinidad and Tobago

The impact of the Prehospital Trauma Life Support (PHTLS) programme, introduced in Trinidad and Tobago in 1992, was assessed by questionnaires completed by 26 medical personnel (MP); 71 ambulance personnel (AP); and 50 non ambulance paramedical personnel (NAP). Of the 23 MP, 45 AP and 38 NAP who were aware of the programme, 19 (82.6 percent) MP, 40(88.9 percent) AP and 25 (65.8 percent) NAP were able to differentiate personnel that had taken the PHTLS programme based on their performance. 32 (71.1 percent) of the AP were PHTLS trained. 24 (53.3 percent) and 4 (9 percent) of the AP identified poor equipment and poor supervision, respectively, as reasons for difficulty in applying PHTLS principles. Improvements observed among those completing the PHTLS programme were: improved resuscitation techniques by 20 (86.9 percent) MP, 38 (84.4 percent) AP and 27 (71.1 percent) NAP; better vital signs recording by 8 (34.8 percent) MP, 27 (60 percent) AP and 8 (21.1 percent) NAP; improved immobilization by 23 (100 percent) MP, 40 (88.9 percent) AP and 33 (86.8 percent) NAP: better haemorrhage control by 22 (95.6 percent) MP, 40 (88.9 percent) AP and 24 (63.2 percent) NAP; appropriate splinting of fractures by 23 (100 percent) MP, 40 (88.9 percent) AP and 32 (84.2 percent) NAP: and increased utilization of oxygen by 15 (65.2 percent) MP, 31 (68.9 percent) AP and 21 (55.3 percent) NAP. 32 (71.1 percent) AP with PHTLS training indicated improvement in their ability to resuscitate and transport trauma victims, with 42 (93.3 percent) reporting improvement in overall prehospital care. Medical, paramedical and ambulance personnel all perceive a significant positive impact of PHTLS training on prehospital trauma care. Although improvements in supervision, documentation and equipment are still required, improved trauma resuscitative techniques after PHTLS training should improve trauma patient outcome in Trinidad and Tobago. (AU)

Impact of the prehospital trauma life support programme in Trinidad and Tobago

The impact of the Prehospital Trauma Life Support (PHTLS) programme, introduced in Trinidad and Tobago in 1992, was assessed by questionnaires completed by 26 medical personnel (MP); 71 ambulance personnel (AP); and 50 non ambulance paramedical personnel (NAP). Of the 23 MP, 45 AP and 38 NAP who were aware of the programme, 19 (82.6) MP, 40 (88.9) AP and 25 (65.8) NAP were able to differentiate personnel that had taken the PHTLS programme based on their performance. 32 (71.1) of the AP were PHTLS trained. 24 (53.3) and 4 (9) of the AP identified poor equipment and poor supervision, respectively, as reasons for difficulty in applying PHTLS principles. Improvements observed among those completing the PHTLS programme were: improved resuscitation techniques by 20 (86.9) MP, 38 (84.4) AP and 27 (71.1) NAP; better vital signs recording by 8 (34.8) MP, 27 (60) AP and 8 (21.1) NAP; improved immobilization by 23 (100) MP, 40 (88.9) AP and 33 (86.8) NAP; better haemorrhage control by 22 (95.6) MP, 40 (88.9) AP and 24 (63.2) NAP; appropriate splinting of fractures by 23 (100) MP, 40 (88.9) AP and 32 (84.2) NAP; and increased utilization of oxygen by 15 (65.2) MP, 31 (68.9) AP and 21 (55.3) NAP. 32 (71.1) AP with PHTLS training indicated improvement in their ability to resuscitate and transport trauma victims, with 42 (93.3) reporting improvement in overall prehospital care. Medical, paramedical and ambulance personnel all perceive a significant positive impact of PHTLS training on prehospital trauma care. Although improvements in supervision, documentation and equipment are still required, improved trauma resuscitative techniques after PHTLS training should improve trauma patient outcome in Trinidad and Tobago.

Lung volumes 24 h after laparoscopic cholecystectomy--justification for early discharge.

OBJECTIVE: To compare lung volumes after laparoscopic cholecystectomy (LC) and open cholecystectomy (OC). DESIGN: Prospective study with matched historical controls. SETTING: Referral teaching hospital. SUBJECTS: Twenty-six healthy female subjects (age 20 to 40 years), 13 of whom had LC. MAIN OUTCOME MEASURES: Vital capacity (VC, % predicted), functional residual capacity (FRC, % predicted) and analgesic frequency (mean +/- SD) over the first 24 h. RESULTS: Immediately after operation, FRC was similarly depressed to 80.4 +/- 1.8% in the OC group and 80.8 +/- 2.3% in the LC group. After 24 h FRC fell to 70.5 +/- 1.9% in the OC group and increased to 91.3 +/- 2.4% in the LC group. VC fell immediately postoperation to 41.4 +/- 4.8% in the OC group but to only 62.2 +/- 1.9% in the LC group. By 24 h, VC improved slightly to 52.5 +/- 2.7% in the OC group but returned to normal, 99.0 +/- 3.2%, in the LC group. Postoperative analgesic frequency over 24 h was less in the LC group, 3.3 +/- 0.8 versus 5.0 +/- 0.8. CONCLUSION: Depression in lung volume is less with LC. A VC that returned to normal and a FRC level not usually associated with pulmonary complications support the practice of discharging LC patients by 24 h postoperation.

Effect of the Advanced Trauma Life Support program on medical students' performance in simulated trauma patient management.

BACKGROUND: Part of the senior medical students' examination at the University of Toronto involves testing with simulated patient management. We compared the performance in these simulations of senior medical students who received Advanced Trauma Life Support (ATLS) training with those who did not receive ATLS training. METHODS: Thirty-two students (group I) completed a standard ATLS course, 12 students (group II) audited the ATLS course, and their performance in the trauma simulations was compared with 44 matched control students (group III) from the same class. Performance in the nontrauma patient simulation stations was also analyzed. The score on each station was standardized to a maximum of 20. The students were also graded on overall Approach (scale of 1 to 5) and pass status. RESULTS: The mean scores (+/-SD, *p < 0.05 compared with other groups) were as follows: Trauma Station, 17.5 +/- 1.02* for group I, 11.76 +/- 0.72* for group II, and 14.67 +/- 0.54* for group III; Nontrauma Station, 13.05 +/- 0.95 for group I, 12.25 +/- 0.72 for group II, and 11.88 +/- 0.80 for group III; Approach, 4.45 +/- 0.50* for group I, 2.09 +/- 0.60* for group II, 3.50 +/- 0.67* for group III. The ATLS-trained and ATLS-audit students had higher scores in the trauma stations than the control group, with the highest scores being in the ATLS-trained group. All ATLS-trained students passed with 62.5% honors and 37.5% passing grades. The ATLS-audit group had 33.3% honors and 66.6% passing grades, compared with the control group who had 84.09% pass, 9.09% borderline, and 6.82% failure in the trauma stations. CONCLUSIONS: The ATLS course, both complete and audit status, prepares students more appropriately for managing trauma patients as judged by trauma simulation scenarios. Consideration should be given for including ATLS as an integral part of the senior medical student curriculum.

Trauma patient outcome after the Prehospital Trauma Life Support program.

BACKGROUND: We have previously demonstrated a significant improvement in trauma patient outcome after the Advanced Trauma Life Support (ATLS) program in Trinidad and Tobago. In January of 1992, a Prehospital Trauma Life Support (PHTLS) program was also instituted. This study assessed trauma patient outcome after the PHTLS program. METHODS: Morbidity (length of stay and degree of disability), mortality, injury severity score, mechanism of injury, age, and sex among all adult trauma patients transported by ambulance to the major trauma hospital were assessed between July of 1990 to December of 1991 (pre-PHTLS, n = 332) and January of 1994 to June of 1995 (post-PHTLS, n = 350). RESULTS: Age, sex distribution, percentage blunt injury, and injury severity score were similar for both groups. Mortality pre-PHTLS (15.7%) was greater than post-PHTLS (10.6%). Length of stay and disability were statistically significantly decreased post-PHTLS. Age, injury severity score, and mechanism of injury were positively correlated with mortality in both periods. The previously reported post-ATLS mortality was similar to the pre-PHTLS mortality. CONCLUSIONS: Post-PHTLS mortality and morbidity were significantly decreased, suggesting a positive impact of the PHTLS program on trauma patient outcome.

Predictors of fetal mortality in pregnant trauma patients.

BACKGROUND: Fetal mortality after trauma is significant. This study was aimed at identifying factors responsible for this high fetal mortality. METHODS: All pregnant trauma patients admitted to the two major Toronto trauma institutions during the period of November of 1991 to February of 1996 with an Injury Severity Score (ISS) > or = 12 were assessed. Data on age, gestation, hypotension, ISS, hemoglobin, blood transfusion, length of stay, disseminated intravascular coagulation (DIC), and specific maternal injury were analyzed retrospectively to determine predictors of fetal mortality by comparison of patients with and without fetal survival. RESULTS: Twenty of a total of 68 pregnant trauma patients qualified for entry into the trauma registry by having an ISS > or = 12. Overall fetal mortality was 65% (13 of 20) for ISS > or = 12, and there was one maternal death (age, 29 years; ISS, 66). There were no statistically significant differences between the fetal death and fetal survival groups in age (29.2 +/- 6.2 vs. 30.4 +/- 3.9 years), gestation (25.3 +/- 10.5 vs. 24.1 +/- 9.2 weeks), lowest systolic blood pressure (98.3 +/- 33.8 vs. 112 +/- 18.0 mm Hg), head injury rate (3 of 13 vs. 1 of 7), extremity injury rate (8 of 13 vs. 2 of 7), abdominal injury rate (4 of 13 vs. 0 of 7), pelvic fracture rate (6 of 13 vs. 1 of 7), and chest injury rate (5 of 13 vs. 3 of 7). However, ISS (27.7 +/- 3.5 vs. 14.2 +/- 11.4), lowest hemoglobin level (78.8 +/- 17.0 vs. 101.9 +/- 17.1), blood transfusions (10.8 +/- 6.3 vs. 0.9 +/- 1.6 units), length of stay (20.9 +/- 16.7 vs. 8.2 +/- 4.9 days), and the incidence of DIC (8 of 13 vs. 0 of 7) were statistically significantly different between the two groups (p < 0.05). All eight patients with abruptio placentae had associated fetal mortality. CONCLUSIONS: Apart from ISS, blood loss, and abruptio placentae; the presence of DIC was the most significant predictor of fetal mortality. This finding may represent stimulation of DIC by placental products entering the maternal circulation after significant intrauterine injury.

Effect of the prehospital trauma life support program (PHTLS) on prehospital trauma care.

BACKGROUND: Improvement in trauma patient outcome has been demonstrated after the implementation of the Prehospital Trauma Life Support (PHTLS) program in Trinidad and Tobago. This study was aimed at identifying prehospital care factors that may explain this improvement. METHODS: All patients transferred by ambulance to the major trauma referral hospital had assessment of airway control, oxygen use, cervical (C)-spine control, and hemorrhage control, as well as splinting of extremities during pre-PHTLS (July of 1990 to December of 1991; n = 332) and post-PHTLS periods (January of 1994 to June of 1995; n = 350). Pre-PHTLS data were compared with post-PHTLS data by chi 2 analysis with a p value < or = 0.05 being considered statistically significant. RESULTS: The frequency (%) increased in the post-PHTLS period for airway control (10 vs. 99.7%), C-spine control (2.1 vs. 89.4%), splinting of extremities (22 vs. 60.6%), hemorrhage control (16 vs. 96.9%), and oxygen use (6.6 vs. 89.5%) when no specific problem was identified. When a specific problem was identified in these areas, the post-PHTLS percentage also increased for airway control (16.2 vs. 100%), C-spine control (25 vs. 100%), splinting of extremities (33.9 vs. 100%), hemorrhage control (18 vs. 100%), and oxygen use (43.2 vs. 98.9%). CONCLUSIONS: Prehospital trauma care has changed after the introduction of the PHTLS program as indicated by more frequent airway control, use of oxygen, control of cervical (C)-spine and hemorrhage, as well as splinting of fractures. This finding was evident not only as a routine but particularly when a specific related problem was identified. This change in prehospital care could be responsible for the improved trauma patient outcome after PHTLS.

Teaching effectiveness of the advanced trauma life support program as demonstrated by an objective structured clinical examination for practicing physicians.

Although the Advanced Trauma Life Support (ATLS) course is now taught internationally, its teaching effectiveness still requires confirmation. The Objective Structured Clinical Examination (OSCE) reliably assesses clinical performance by utilizing standardized patients. An OSCE of eight 15 minute trauma patient stations and two 40 item MCQ tests were used to test the teaching effectiveness of the ATLS program in 32 practicing physicians who applied for an ATLS program in Trinidad and Tobago. The physicians were randomly assigned to an ATLS group (n = 16) that completed the ATLS course and a non-ATLS group (n = 16). Before and after the ATLS course, all physicians completed MCQ tests and trauma OSCE. Mean (+/- SD) OSCE scores (standardized to 20) ranged from 9.8 +/- 1.7 to 10.0 +/- 1.7 and 9.5 +/- 1.8 to 10.8 +/- 1.3 in the ATLS and non-ATLS groups, respectively, prior to the ATLS course (NS). Post-ATLS OSCE scores ranged from 15.9 +/- 1.7 to 17.6 +/- 1.7 in the ATLS group (p < 0.05 compared to pre-ATLS) and 9.5 +/- 1.4 to 10.1 +/- 1.3 in the non-ATLS group, which did not improve their OSCE scores. Adherence to priorities was graded 1 to 7 with the pre-ATLS grades of 1.7 +/- 0.6 (ATLS) and 1.8 +/- 0.7 (non-ATLS) and post-ATLS grades of 6.4 +/- 1.1 (ATLS) and 2.1 +/- 0.6 (non-ATLS). Organized approach to trauma was graded 1 to 5 with pre-ATLS grades of 1.6 +/- 0.5 (ATLS) and 1.7 +/- 0.6 (non-ATLS) and post-ATLS grades of 4.5 +/- 0.6 (ATLS) and 1.9 +/- 0.6 (non-ATLS). Pre-ATLS MCQ scores (%) were similar: 53.1 +/- 8.4 (ATLS) and 57.3 +/- 5.4 (non-ATLS), but post-ATLS scores were greater in the ATLS group: 85.8 +/- 7.1 (ATLS) and 64.2 +/- 3.6 (non-ATLS). Our data support the teaching effectiveness of the ATLS program among practicing physicians as measured by improvement in OSCE scores, adherence to trauma priorities, maintenance of an organized approach to trauma care, and cognitive performance in MCQ examinations.

Trauma ultrasound workshop improves physician detection of peritoneal and pericardial fluid.

Hemoperitoneum represents a major indication for surgical intervention after trauma. To improve the ability of surgical residents and trauma physicians to detect intraperitoneal and pericardial fluid using ultrasound as a diagnostic modality, we conducted a focused trauma ultrasound workshop consisting of discussion of ultrasound physics, demonstration of instrumentation, review of pertinent literature, videotaped demonstration, and "hands-on" teaching of the skills utilizing live patient models. The ultrasound probes were placed in four standard locations--right and left upper quadrants, epigastrium, and Pouch of Douglas. Skills acquisition was tested by pre- and postworkshop performance on 12 sonograms (3 for each location, 6 were positive for fluid). Thirty physicians (21 residents and 9 staff: Group I) who attended the workshop were compared to 30 matched controls (Group II). The results (means +/- SD) were as follows (R = number right, I = number of "indeterminate," W = number of wrong responses out of 12, *P < 0.05 compared to Group II): [Table: see text] False positive (%) and false negative (%) decreased from 12.9 +/- 1.5 to 8.9 +/- 5.3 and 15.0 +/- 10.4 to 5.0 +/- 5.2, respectively, in Group I but did not change in Group II. Postworkshop ability to detect fluid was significantly (P < 0.05) improved, with no major differences between residents and staff. Our data suggest that these workshops can significantly improve the skills of nonradiologists in sonographic identification of pericardial and intraperitoneal fluid and should therefore be considered an essential component of ultrasound training for trauma physicians.

Attrition of cognitive and trauma management skills after the Advanced Trauma Life Support (ATLS) course.

OBJECTIVE: To test the attrition of cognitive and trauma management skills among practising physicians after the Advanced Trauma Life Support (ATLS) course. DESIGN, MATERIALS, AND METHODS: Sixty practising physicians who completed the ATLS course had comparative assessment of cognitive skills (with multiple choice questions, MCQ) pre-ATLS, immediately post-ATLS, at 6 months (group A), 2 years (group B), 4 years (group C), and 6 years (group D) after the course. Trauma management skills were also compared using eight Objective Structured Clinical Examination (OSCE) trauma stations completed by the four groups of physicians. MEASUREMENTS AND MAIN RESULTS: Pre-ATLS MCQ scores (54.2 +/- 4.2 to 59.8 +/- 5.3%) and immediately post-ATLS MCQ scores (85.9 +/- 5.1 to 87.7 +/- 5.3%) were similar in all four groups. Follow-up MCQ scores were 77.8 +/- 3.6% at 6 months 70.6. +/- 1.9% at 2 years, 69.4 +/- 1.7% at 4 years, and 68.9 +/- 2.0% at 6 years. OSCE scores out of a maximum of 20 were 16.8 +/- 0.3 at 6 months, 13.9 +/- 0.1 at 2 years, 12.0 +/- 0.1 at 4 years, and 11.9 +/- 0.1 at 6 years. Adherence-to-priorities scores (maximum, 7) were 6.6 +/- 0.2 at 6 months, 6.8 +/- 0.1 at 2 years, 6.6 +/- 0.1 at 4 years, and 6.6 +/- 0.1 at 6 years. Organized-approach scores (maximum, 5) were 4.8 +/- 0.1 at 6 months, 4.6 +/- 0.2 at 2 years, 4.7 +/- 0.2 at 4 years, and 4.6 +/- 0.2 at 6 years. Using the MCQ 80% pass mark criterion, at least 50% of physicians fail by 6 months and all fail this cognitive test thereafter. CONCLUSIONS: Whereas cognitive and trauma management skills decline after the ATLS, these skills are maintained at similar levels between 4 and 6 years after ATLS. A 50% failure rate occurs within 6 months and maximum attrition of cognitive skills occurs within 2 years of ATLS completion. Major principles of adherence to priorities and maintenance of an organized approach to trauma care are preserved for at least 6 years after ATLS.

Gross and histologic effects of topical misoprostol on canine gastric mucosa.

This study reports the histological effects of topical misoprostol, a synthetic PGE1 analog, administered in varying dosages on the resting canine gastric mucosa. Misoprostol did not macroscopically or microscopically damage the mucosa but its presumed permeability effects on the gastric vasculature induced marked edema of the mucosa and submucosa. Consistent features included increased thickness of both layers, dilated interglandular regions of the lamina propria, marked subepithelial edema, reduced depth and width of gastric foveolae, vasodilation of the vascular channels, reduced height of surface epithelial cells, swelling of their basolateral intercellular spaces, and increased amounts of surface adherent mucus. It is speculated that the mucosal edema, in addition to an increased mucus layer, may be important in the mechanism of gastric cytoprotection by increasing the distance of penetration or absorption for a mucosal-damaging agent, diluting its concentration, and disseminating any focal accumulations of red blood cells.

A controlled study of human resting gastric mucosal blood flow by endoscopic laser-Doppler flowmetry.

We investigated regional variation in resting focal gastric mucosal blood flow obtained by endoscopic laser-Doppler flowmetry in patients with symptoms of dyspepsia or peptic ulcer (N = 12) and asymptomatic healthy volunteers (N = 6). Mucosal blood flow was measured for 1 min at the duodenum (first part), prepylorus, antrum and body (anterior and posterior walls), angularis, mid-greater curvature, fundus, and distal esophagus. At all sites, mean +/- SE blood flow in patients was 71.88% of the corresponding value in volunteers (1.15 +/- 0.10 and 1.60 +/- 0.13 volts, p less than 0.02, t test). In both groups, blood flow was highest in the fundus, followed by the body and lowest in the antrum; the angularis had a high blood flow, second only to the fundus. There was no correlation between age and blood flow. We conclude that regional variation in resting gastric mucosal blood flow exists in health and disease.

Cobalt as a gastric juice volume marker: comparison of two methods of estimation.

We investigated the use of cobalt-EDTA, a novel, nonabsorbable liquid phase marker, in the estimation of secretory volumes during topical misoprostol (synthetic PGE, analog) administration in the canine chambered gastric segment. We compared atomic absorption spectrophotometry (AAS) and instrumental neutron activation analysis (INAA) in the estimation of [Co]. Mucosal bathing solutions containing cobalt-EDTA were instilled into and recovered from the chamber by gravity every 15-min period as follows: (i) basal--60 min; (ii) misoprostol periods--150 min (plus 0.1-, 1-, 10-, 100-, and 1000-micrograms doses of misoprostol for two periods per dose). The recovered solutions were analyzed for [Co] by AAS and INAA. Total cobalt recovery by AAS after chamber washout was 102.97 +/- 0.98%. Mean +/- SE volumes (12.14 +/- 0.33 and 13.24 +/- 0.60 ml/15 min) obtained respectively from AAS and INAA were significantly higher (P less than 0.001) than the recovered mean volumes (10.51 +/- 0.17 ml/15 min). The percentage error in volume collection increased (range: 9.3-52.7%) with the volume of secretion. Values of [Co] obtained by the two techniques were comparable and not significantly different from each other (P greater than 0.05). INAA-estimated mean +/- SE [Co] showed consistently higher coefficients of variation. Spectra obtained for all samples during INAA measurements showed significant Compton background activity from 24Na and 38Cl. Cobalt-EDTA did not grossly or histologically damage the gastric mucosa. We conclude that cobalt is not adsorbed, absorbed, or metabolized, and is a suitable and reliable volume marker in this model.(ABSTRACT TRUNCATED AT 250 WORDS)

The dose-response of canine focal gastric mucosal blood flow to misoprostol.

We studied the dose-response of focal gastric mucosal blood flow measured simultaneously by laser-Doppler flowmetry and hydrogen gas clearance in the canine chambered gastric segment to topical misoprostol (0.1, 1.0, 10, 100, and 1000 micrograms in 10 ml of 150 mM NaCl for two 15-min periods per dose). Simultaneously obtained mucosal blood flow values showed a highly significant linear correlation (r = 0.63, n = 20, p less than 0.01) in the basal but not misoprostol periods between the two techniques. Laser-Doppler flowmetry measured a dose-dependent increase in blood flow (Emax = 6.4 +/- 2.8 V at the 100-micrograms dose; equivalent to 92.8% increase above the basal mean blood flow value; ED50 = 1.0 micrograms). Peak increase in blood flow by laser-Doppler flowmetry after dosing was attained in 6.1 +/- 0.7 min and maintained for 1.9 +/- 0.3 min. In contrast, hydrogen gas clearance showed a gradual decline in blood flow after misoprostol administration throughout all experiments. The duration of each hydrogen gas clearance measurement was 13.1 +/- 0.1 min. In conclusion, misoprostol dose-dependently and transiently increases focal gastric mucosal blood flow. However, only laser-Doppler flowmetry is sensitive enough to detect it. Although it can measure steady-state blood flow, owing to the duration of one measurement, hydrogen gas clearance is incapable of detecting rapid flow changes.

Ionic fluxes induced by topical misoprostol in canine gastric mucosa.

We studied the dose response of ionic fluxes in canine chambered gastric segment mucosa to increasing doses of topical misoprostol (0.1, 1, 10, 100, and 1000 micrograms). The fluxes were also correlated with the simultaneous changes in focal gastric mucosal blood flow measured by laser-Doppler flowmetry. After misoprostol administration, there was a dose-dependent increase in focal gastric mucosal blood flow (Emax = 8.23 +/- 3.25 V at 10 micrograms; ED50 = 1.05 micrograms), pH, and the outputs of ions (Na+, K+, Cl-, and HCO3-) and fluid (Emax for pH and fluxes greater than or equal to 1000 micrograms). ED50 values for these outputs ranged from 215.40 to 340 micrograms (mean +/- SE = 279.08 +/- 24.27 micrograms). H+ output showed a dose-dependent decrease to zero at the 10-micrograms dose, the dose at and after which net HCO3- secretion became obvious. The slopes of the dose-response curves for the fluxes of fluid, Na+, K+, Cl-, and HCO3- were significantly different (p less than 0.01) from the slope of the curve for mucosal blood flow changes. There were no correlations between the changes in these fluxes and blood flow changes. Na+ and Cl- were the predominant cation (98.84%) and anion (98.19%), respectively, in the misoprostol-induced secretion. Misoprostol stimulates a composite alkaline gastric nonparietal secretion, predominantly Na+ and Cl-, but also containing K+ and HCO3-. Our results suggest different mechanisms for the effects on nonparietal secretion and focal gastric mucosal blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric mucosal blood flow in misoprostol pretreated aspirin-induced ulceration.

To determine whether topical misoprostol (a synthetic PGE analog) pretreatment will increase or prevent a decrease in gastric mucosal blood flow (GMBF) during topical aspirin administration, we studied focal GMBF simultaneously by hydrogen gas clearance in a split canine gastric chamber model with one side as control. In the test chamber, immediately after topical misoprostol, there was a transient and significant increase (18%) in GMBF (55.71 +/- 7.80 to 65.84 +/- 6.12 mL/min/100 g; p less than 0.05). After 15 minutes, GMBF returned to premisoprostol levels and then showed a graded drop throughout the aspirin and postaspirin periods. No grossly visible mucosal lesions were observed. In the control chamber, mucosal lesions were observed 45 minutes after aspirin administration accompanied by a graded drop in GMBF throughout the experiments. Misoprostol neither produced a sustained increase in GMBF nor prevented the subsequent reduction in GMBF induced by aspirin. Therefore, maintenance of GMBF may not be important in cytoprotection by misoprostol. The sustained nonparietal secretion induced by this synthetic PGE1 analog may be important in gastric cytoprotection.

Focal gastric mucosal blood flow by laser-Doppler and hydrogen gas clearance: a comparative study.

We compared focal gastric mucosal blood flow (GMBF) values simultaneously obtained by laser-Doppler flowmetry (LDF) and hydrogen gas clearance (HGC) from the same point in a chambered segment model of the gastric corpus in two sets of experiments (Experiments 1 and 2) involving nine anesthetized dogs (weighing 20-30 kg). We also investigated the feasibility of obtaining a conversion factor for LDF signal to absolute flow values. The GMBF values showed a highly significant linear correlation within individual experiments and for the combined data in experiments 1 (r = 0.7132, P less than 0.0001, n = 37) and 2 (r = 0.5660, P less than 0.0001, n = 61). The combined data did not corroborate a common regression line hypothesis in both experiments (Experiment 1: F = 6.59, P less than 0.0005; Experiment 2: F = 10.57, P less than 0.0005). There was a statistically significant difference between the slopes of the 5 and 4 linear regression lines obtained in Experiments 1 (F = 13.15, P less than 0.0005) and 2 (F = 21.14, P less than 0.0005), respectively. The LDF signal was stable and optical coupling is not a problem in this experimental model. HGC and GMBF values were reliable and highly reproducible within dog measurements. We conclude that LDF and HGC are comparable in the measurement of focal GMBF. Our data, however, did not suggest the existence of a conversion factor for LDF signal to absolute flow values from experiment to experiment. Conversion will have to be within individual experiments. Thus, LDF may only be useful in situations where qualitative changes in focal blood flow are investigated.

Focal gastric mucosal blood flow in aspirin-induced ulceration.

Focal gastric mucosal blood flow was studied during aspirin injury by hydrogen gas clearance in a chambered segment model of canine gastric corpus. Measurements were made simultaneously every 15 minutes at ulcerated and nonulcerated areas 1.5 hours before, during (20 mM of aspirin in 150 mM of HCl for 1 hour), and 2 hours after exposure of the mucosa to topical aspirin. There was a highly significant decrease (p less than 0.001) in flow at the ulcerated areas 30 minutes after exposure to aspirin, coinciding with the appearance of focal mucosal pallor followed by subsequent hemorrhagic foci and ulceration. This was not followed by recovery to basal flow values. Blood flow to the non-ulcerated areas was significantly but less severely reduced than in the ulcerated areas (p less than 0.05) 90 minutes after exposure to aspirin. This was followed by recovery to basal levels. It is proposed that aspirin induces reduction of focal mucosal blood flow of varying degrees and that mucosal areas with flow reduced to below a "critical value" develop gross damage.