1
|
Tolbert MK, Spencer A, Lynch AM, Papich MG, Lidbury JA. Capsule endoscopy detects insufficient treatment of gastric bleeding in a dog with chronic hepatitis. VETERINARY RECORD CASE REPORTS 2020. [DOI: 10.1136/vetreccr-2020-001238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
| | - Ashley Spencer
- Department of Clinical SciencesNorth Carolina State University College of Veterinary MedicineRaleighNorth CarolinaUSA
| | - Alex M Lynch
- Department of Clinical SciencesNorth Carolina State University College of Veterinary MedicineRaleighNorth CarolinaUSA
| | - Mark G Papich
- College of Veterinary MedicineNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | - Jonathan A Lidbury
- Small Animal Clinical SciencesTexas A&M UniversityCollege StationTexasUSA
| |
Collapse
|
2
|
Wong BJ, Sheriff DD. Role of splanchnic constriction in governing the hemodynamic responses to gravitational stress in conscious dogs. J Appl Physiol (1985) 2011; 111:40-7. [PMID: 21512154 DOI: 10.1152/japplphysiol.01290.2010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Octreotide is a somatostatin analog that constricts the splanchnic circulation, thereby improving orthostatic tolerance. We tested the hypotheses that octreotide improves orthostatic tolerance by 1)increasing cardiac filling (right atrial) pressure via reductions in vascular capacity; 2) by causing an upward (i.e., cranial) shift of the hydrostatic indifferent point; and 3) by increasing arterial pressure via a reduction in total vascular conductance. Studies were carried out in acepromazine-sedated, hexamethonium-treated atrioventricular-blocked conscious dogs lightly restrained in lateral recumbency. Beat-by-beat cardiac output was held constant via computer-controlled ventricular pacing at rest and during 30 s of 30° head-up tilt. Octreotide (1.5 μg/kg iv) raised right atrial pressure by 0.5 mmHg and raised mean arterial pressure by 11 mmHg by reducing total vascular conductance (all P < 0.05). Right atrial pressure fell by a similar amount in response to tilting before and after octreotide, thus there was no difference in location of the hydrostatic indifferent point. These data indicate that octreotide improves orthostatic tolerance by decreasing total vascular conductance and by increasing cardiac filling pressure via a reduction in unstressed vascular volume and not by eliciting a cranial shift of the location of the hydrostatic indifferent point.
Collapse
Affiliation(s)
- Brett J Wong
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, USA
| | | |
Collapse
|
3
|
Leung FW. Endoscopic reflectance spectrophotometry and visible light spectroscopy in clinical gastrointestinal studies. Dig Dis Sci 2008; 53:1669-77. [PMID: 17932761 DOI: 10.1007/s10620-007-0026-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Accepted: 09/11/2007] [Indexed: 12/13/2022]
Abstract
The use of reflectance spectrophotometry (RS) for mucosal hemodynamic measurement relies on the recognition of changes in indexes of mucosal hemoglobin concentration and oxygen saturation. Endoscopic application in clinical studies has confirmed important observations demonstrated in animal experiments. The vasoconstriction induced by propranolol, vasopressin, glypressin, or somatostatin in the portal hypertensive gastric mucosa and the reduction of gastroduodenal mucosal perfusion by nonsteroidal anti-inflammatory drugs (NSAIDs) or smoking, mesenteric venoconstriction associated with systemic hypoxia, and acid-induced duodenal hyperemia are important examples. Prognostic predictions include the development of stress-induced gastric ulcerations in patients with significant reductions in gastric perfusion after thermal or head injury, or the demonstration of delayed gastric or duodenal ulcer healing when the hyperemia at the ulcer margin fails to materialize. In mechanical-ventilator-dependent patients with sepsis, a significantly reduced gastric mucosal RS measurement portends a grave prognosis (mortality >80%). Recent advances in technology resulted in the construction and validation of instruments for visible light spectroscopy. Measurements focused on tissue oxygen saturation demonstrated epinephrine and vessel-ligation-induced vasoconstriction, the absence of ischemia in radiation-induced rectal telangiectasias, and gut ischemia responsive to revascularization treatment. Endoscopic RS and visible light spectroscopy are suitable for assessing the role of blood flow in conditions with a lesser degree of ischemia and for testing the hypothesis that functional dyspepsia and dysmotility syndromes may be due to gut ischemia.
Collapse
Affiliation(s)
- Felix W Leung
- Division of Gastroenterology, Research and Medical Services, Sepulveda Ambulatory Care Center, VA Greater Los Angeles Healthcare System, 16111 Plummer Street, North Hills, CA 91343, USA.
| |
Collapse
|
4
|
Mitsuoka Y, Hata J, Haruma K, Manabe N, Tanaka S, Chayama K. New method of evaluating gastric mucosal blood flow by ultrasound. Scand J Gastroenterol 2007; 42:513-8. [PMID: 17454863 DOI: 10.1080/00365520600955021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Evaluation of gastrointestinal blood flow is important. However, a non-invasive measurement method has not yet been established. The aim of this study was to compare measurement of normal gastric mucosal blood flow by advanced dynamic flow (ADF) flash echo imaging (FEI) with intravenous Levovist with measurement by laser Doppler flowmetry (LDF) to clarify the usefulness of ADF-FEI and thereby consider its feasibility as a non-invasive gastric mucosal blood flow measurement method. MATERIAL AND METHODS Measurements were obtained in 25 beagle dogs (8-month-old males, body-weight, 10.6+/-1.3 kg, mean+/-SD). After insertion of a gastrointestinal endoscope, gastric mucosal blood flow at the greater curvature of the corpus was measured by LDF, and images of gastric mucosal blood flow were obtained by ADF-FEI (frequency; 4.7 MHz) with intravenous injection of Levovist (30 mg/kg). ADF-FEI images were transferred to a personal computer. A region of interest was set on the mucosa of the greater curvature of the corpus, and a time intensity curve (TIC) was plotted from the measured echo intensities. The area under the curve (AUC) calculated from the TIC and the median flow determined by LDF were analyzed and compared. RESULTS Evaluation of normal gastric mucosal blood flow by ADF-FEI was possible in all animals. There was a strong, significant correlation between gastric mucosal blood flow measured by LDF and the AUC obtained by ADF-FEI (r=0.869, p<0.0001). CONCLUSIONS Gastric mucosal blood flow can be accurately measured by ADF-FEI with intravenous Levovist injection.
Collapse
Affiliation(s)
- Yutaka Mitsuoka
- Department of Medicine and Molecular Science, Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, Japan
| | | | | | | | | | | |
Collapse
|
5
|
Friedland S, Soetikno R, Benaron D. Reflectance spectrophotometry for the assessment of mucosal perfusion in the gastrointestinal tract. Gastrointest Endosc Clin N Am 2004; 14:539-53, ix-x. [PMID: 15261201 DOI: 10.1016/j.giec.2004.03.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Reflectance spectrophotometry (RS) is an optical technology that has been used for nearly three decades in the measurement of tissue hemoglobin oxygen saturation in the gastrointestinal tract. The technology has evolved substantially throughout this period,and commercial devices are now available for use in clinical trials. Numerous studies have used RS to investigate the importance of mucosal perfusion in disorders such as ulcer disease, portal hypertension, and septic shock. More recently, the technique has been applied to measure changes in perfusion in response to infusion of vasoactive medications and maneuvers such as cardiopulmonary bypass. The results of current trials investigating the application of RS in critical care monitoring and vascular interventions will likely determine whether the technique will evolve from predominantly a research tool to a clinically useful device.
Collapse
Affiliation(s)
- Shai Friedland
- Department of Medicine, Stanford University Medical Center, Alway Building, Room M211, 300 Pasteur Drive, MC: 5187, Stanford, CA 94305-5187, USA.
| | | | | |
Collapse
|
6
|
Tsui CP, Sung JJY, Leung FW. Role of acute elevation of portal venous pressure by exogenous glucagon on gastric mucosal injury in rats with portal hypertension. Life Sci 2003; 73:1115-29. [PMID: 12818720 DOI: 10.1016/s0024-3205(03)00413-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Time-course studies revealed the increased susceptibility of the gastric mucosa to noxious injury in portal hypertension correlates with the level of elevated portal venous pressure and hyperglucagonemia. Whether acute elevation of portal venous pressure by exogenous glucagon aggravates such injury is not known. We tested the hypothesis that glucagon in a dose sufficient to acutely elevate portal venous pressure aggravates noxious injury of the gastric mucosa in rats with portal hypertension. Infusion of a portal hypotensive dose of somatostatin should reverse these changes. In anesthetized rats with portal vein ligation, glucagon, somatostatin or the combination was administered intravenously in a randomized, coded fashion. Acidified ethanol-induced gastric mucosal injury was determined. Portal venous pressure and gastric mucosal perfusion and oxygenation (reflectance spectrophotometry) were monitored to confirm the effects of the respective intravenous treatments. Exogenous glucagon exacerbated acidified ethanol-induced gastric mucosal injury. The exacerbation was attenuated by somatostatin. These changes paralleled the portal hypertensive and hypotensive effects of glucagon and somatostatin, respectively. Our data suggest that a unique mechanism is triggered with the onset of portal hypertension. In an antagonistic manner, glucagon and somatostatin modulate this novel mechanism that controls portal venous pressure and susceptibility of the gastric mucosa to noxious injury.
Collapse
Affiliation(s)
- C P Tsui
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, China
| | | | | |
Collapse
|
7
|
Ramirez FC, Padda S, Medlin S, Tarbell H, Leung FW. Reflectance spectrophotometry in the gastrointestinal tract: limitations and new applications. Am J Gastroenterol 2002; 97:2780-4. [PMID: 12425548 DOI: 10.1111/j.1572-0241.2002.07022.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Reflectance spectrophotometry (RS) assesses blood flow changes by measuring an index of Hb concentration (IHB) and index of Hb oxygen saturation (ISO2). We tested the following hypotheses: 1) endoscopic RS measurements obtained by two observers and with the aid of fiber optic and video endoscopes are similar, and 2) the method is suitable for documenting mesenteric venoconstriction associated with systemic hypoxia and blood flow autoregulation associated with hemorrhagic hypotension. METHODS Study 1: two investigators obtained baseline gastric mucosal RS measurements in anesthetized rats (n = 3) before and after stepwise reduction of blood pressure induced by arterial hemorrhage. Study 2: subjects were examined by both fiber optic and video endoscopes. Endoscopic RS measurements were obtained at 20 cm from the anal verge. Study 3: video endoscope was used to obtain RS measurements in oxygen-dependent patients on and off oxygen treatment. Study 4: the procedures in study 1 were repeated in five additional rats by one of the investigators. RESULTS Study 1: there was good agreement between the measurements of IHB and ISO2 between the two investigators. Study 2: video endoscope-assisted measurements were consistently lower. Study 3: cessation of oxygen treatment produced a significant drop in oxygen saturation (pulse oximetry), decline in ISO2, and rise in IHB. Study 4: when blood pressure varied between 90% and 40% of baseline, gastric mucosal blood flow (IHB) was maintained at approximately 70% of baseline level. CONCLUSIONS We confirmed that reproducible measurement can be obtained by different investigators using standardized techniques. Standardization of endoscopic equipment is also necessary to overcome the significant limitation of endoscopic equipment on RS measurements. RS measurements can document mesenteric venoconstriction associated with systemic hypoxia and blood flow autoregulation associated with hemorrhagic hypotension.
Collapse
Affiliation(s)
- Francisco C Ramirez
- Research Service, Carl T. Hayden VA Medical Center, Phoenix, Arizona 85012, USA
| | | | | | | | | |
Collapse
|
8
|
Kovacs TOG, Jensen DM. Recent advances in the endoscopic diagnosis and therapy of upper gastrointestinal, small intestinal, and colonic bleeding. Med Clin North Am 2002; 86:1319-56. [PMID: 12510456 DOI: 10.1016/s0025-7125(02)00079-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Endoscopy has become the first and primary diagnostic and therapeutic modality in the management of patients with severe gastrointestinal bleeding. Panendoscopy, push enteroscopy, and colonoscopy provide the diagnostic, prognostic, and therapeutic elements to improve patient outcomes and to reduce morbidity and mortality from severe GI hemorrhage. Recent improvements in endoscopic hemostatic techniques and in imaging modalities using wireless capsule endoscopy suggest that diagnostic and therapeutic endoscopy will be even more important in determining patient outcomes in the future.
Collapse
Affiliation(s)
- Thomas O G Kovacs
- Division of Digestive Diseases, Department of Medicine, University of California at Los Angeles, School of Medicine, CURE Digestive Diseases Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA.
| | | |
Collapse
|
9
|
Kubba AK, Dallal H, Haydon GH, Hayes PC, Palmer KR. The effect of octreotide on gastroduodenal blood flow measured by laser Doppler flowmetry in rabbits and man. Am J Gastroenterol 1999; 94:1077-82. [PMID: 10201486 DOI: 10.1111/j.1572-0241.1999.929_b.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE The somatostatin analogue, octreotide is valuable in the management of variceal bleeding, and it has been suggested that it may stop peptic ulcer hemorrhage by reducing gastroduodenal blood flow or increasing intragastric pH. The aim of this study was to determine the effect of intravenous octreotide infusion on gastroduodenal mucosal blood flow and gastric pH. METHODS Seven New Zealand white rabbits and five healthy human volunteers were used. Mucosal blood flow was measured using a laser Doppler flowmeter (LDF). The Doppler probe was positioned in the upper gastrointestinal tract of the seven rabbits and five human volunteers. Blood flow was measured before and after octreotide infusion. RESULTS In the animal experiments, mucosal blood flow was decreased in a dose dependent manner in the gastric body (209.1-56.3 U) (p < 0.008), antrum (143.3-33.3 U) (p < 0.02) and duodenum (254-67.6 U) (p < 0.016) by doses of octreotide ranging from 10-50 microg/kg of body weight. In the human studies, mucosal blood flow was decreased in the gastric body (p < 0.016) and antrum (p < 0.009) after octreotide infusion (dose 1-1.5 microg/kg). Intragastric pH was significantly increased (p < 0.05). The change was not associated with systemic hemodynamic changes. CONCLUSIONS Gastroduodenal mucosal blood flow was reduced and intragastric pH increased by octreotide. This agent could be helpful in the management of gastroduodenal mucosal bleeding.
Collapse
Affiliation(s)
- A K Kubba
- Western General Hospital, and The Centre for Liver and Digestive Diseases, Royal Infirmary of Edinburgh, Scotland
| | | | | | | | | |
Collapse
|
10
|
Abstract
In the present article we describe updated information concerning the clinical feature of portal-hypertensive gastropathy (PHG), which is characterized by mucosal and submucosal vascular dilatation without inflammation. Although this lesion represents non-variceal bleeding, there is a wide variation of its prevalence. Portal pressure and some humoral factors may play important roles in its pathogenesis. Gastric acid secretory activity is reduced, whereas the gastric mucosal barrier is impaired. With regard to gastric mucosal haemodynamics, whether 'overflow' (i.e. active congestion) or 'stasis' (i.e. passive congestion) cause gastric mucosal hyperaemia is not known. A severe lesion is a potential source of bleeding, while mild lesions are of little clinical significance and endoscopic variceal obliteration aggravates PHG in some patients. In the treatment of PHG, pharmacological (e.g. propranolol), surgical (e.g. portosystemic shunt) and radiological (e.g. transjugular intrahepatic portosystemic shunt) procedures may be useful in preventing bleeding from PHG.
Collapse
Affiliation(s)
- A Toyonaga
- Department of Medicine II, Kurume University School of Medicine, Japan
| | | |
Collapse
|
11
|
Li MK, Sung JJ, Woo KS, Sanderson J, Leung NW, Yu LM, Tsui CP, Chung SC, Leung FW. Somatostatin reduces gastric mucosal blood flow in patients with portal hypertensive gastropathy: a randomized, double-blind crossover study. Dig Dis Sci 1996; 41:2440-6. [PMID: 9011455 DOI: 10.1007/bf02100140] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Agents which decrease gastric mucosal blood flow (GMBF) are postulated to have beneficial effects in arresting gastrointestinal bleeding in cirrhotic patients with portal hypertension. Our objective was to test the hypothesis that in a dose that significantly lowers wedged hepatic venous pressure (WHVP), a bolus injection of somatostatin will significantly decrease GMBF in patients with portal hypertensive gastropathy (PHG). In this placebo-controlled, double-blind, crossover study, 20 cirrhotic patients with PHG were randomly assigned to receive either somatostatin followed by placebo (Group A) or placebo followed by somatostatin (Group B). Wedged hepatic venous pressure was monitored. GMBF in the antrum and corpus was assessed by reflectance spectrophotometry. Indices of hemoglobin concentration (IHb) and indices of oxygen content (ISO2) were recorded. Nine patients were assigned to Group A, and 11 to Group B. Mild PHG was seen in 16 patients, and severe PHG in 4 patients. Baseline WHVP, IHb, and ISO2 were similar in both treatment groups. Wedged hepatic venous pressure (WHVP) was significantly lowered [median, 17.6%; interquartile range (-27.0,-12.6%); P = 0.0008] after a 250-microg bolus injection of somatostatin. This dose of somatostatin significantly reduced IHb both in the antrum [-10.2% (-23.4, 0.4%)] and in the corpus [-5.8% (-16.6, 5.6%)] compared to placebo (P = 0.02 and 0.04, respectively). Intravenous bolus injection of 250 microg somatostatin significantly reduces WHVP and GMBF in patients with PHG. Whether this ability to decrease the GMBF in PHG makes somatostatin an effective treatment in acute gastrointestinal bleeding in PHG deserves to be studied.
Collapse
Affiliation(s)
- M K Li
- Department of Medicine, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Sung JJ, Tsui CP, Li MK, Leung FW. Somatostatin attenuates the hyperdynamic circulatory state in the gastric mucosa of rats with portal hypertension. Scand J Gastroenterol 1995; 30:921-6. [PMID: 8578194 DOI: 10.3109/00365529509101602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Portal hypertensive gastropathy is characterized by a hyperdynamic circulatory state in the gastric mucosa. We assessed the effect of bolus injection of somatostatin on gastric mucosal perfusion in a rat model of portal hypertension. We tested the hypothesis that somatostatin will reduce gastric mucosal perfusion in portal hypertension. METHODS Portal hypertension was induced by two-stage portal vein ligation (PVL). Two weeks after PVL significant elevation of portal venous pressure was demonstrated. Gastric mucosal hemodynamic changes were measured by reflectance spectrophotometry, which records the indexes of mucosal hemoglobin oxygen saturation (ISO2) and mucosal hemoglobin concentration (IHB). RESULTS After an intravenous bolus of 1 microgram somatostatin significant reductions of ISO2 and IHB were demonstrated in the rats with PVL (ISO2, -34 +/- 5%; IHB, -15 +/- 2%) and the controls (ISO2, -26 +/- 4%; IHB, -15 +/- 2%). A dose-response relationship was shown by using 0.01, 0.1, and 1 microgram of somatostatin. Somatostatin did not induce other hemodynamic changes except a transient drop in systemic blood pressure of 8-10%. CONCLUSION The significant reductions of gastric mucosal ISO2 and IHB by somatostatin support the hypothesis that somatostatin is capable of attenuating the hyperdynamic circulatory state in the gastric mucosa of rats with portal hypertension and may have a beneficial effect on portal hypertensive gastropathy. This hypothesis deserves to be evaluated in clinical studies.
Collapse
Affiliation(s)
- J J Sung
- Dept. of Medicine, Prince of Wales Hospital, Chinese University of Hong Kong
| | | | | | | |
Collapse
|
13
|
Leung FW, Lo SK, Phan QQ, Leung JW, Yanni GS, Jing J. Factors influencing reflectance spectrophotometric measurements of gastrointestinal mucosal blood flow. Gastrointest Endosc 1995; 41:18-24. [PMID: 7698620 DOI: 10.1016/s0016-5107(95)70271-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although the technique of endoscopic reflectance spectrophotometry has been applied in clinical studies, factors that modify the reproducibility of measurements have not been assessed systematically. To determine the limitations of the technique, measurements were made while endoscopic light intensity, systemic oxygen saturation, and orientation of the measuring probe were varied. The effects of hemorrhagic hypotension and exposure of the mucosa to 10% dextrose were also studied. When a large number (n = 480) of measurements in the human colon were considered, endoscopic light significantly decreased the index of oxygen saturation (ISO2) and increased the index of hemoglobin concentration (IHB). The decrease in ISO2, however, was small and unlikely to be of clinical importance despite being statistically significant. In one subject with chronic lung disease and baseline hypoxemia, administration of supplemental oxygen significantly increased oxygen saturation at the finger tip as measured by an oximeter and ISO2 of the buccal mucosa as measured by reflectance spectrophotometry. Varying the angle between the measuring probe and the gastric mucosa in rats from 90 degrees to 60 degrees did not affect ISO2 or IHB measurements. At 45 degrees, however, IHB but not ISO2 was significantly increased. Ischemia subsequent to induction of hemorrhagic hypotension and hyperemia induced by administration of 10% dextrose could be demonstrated reproducibly. We conclude that by lowering the intensity of endoscopic light and providing supplemental oxygen, errors in the measurement of IHB and ISO2, respectively, can be minimized. Minor deviations from the perpendicular orientation do not significantly affect ISO2 and IHB measurements. Attention to these details enhances the accuracy of endoscopic reflectance spectrophotometric recordings of ISO2 and IHB in clinical studies.
Collapse
Affiliation(s)
- F W Leung
- Research and Medical Services, Sepulveda VAMC, California 91343, USA
| | | | | | | | | | | |
Collapse
|