Biomedical subjects

C J Hauser

Publications and source records attributed to C J Hauser.

At least 55 records · Page 3Linked to original sources

PubMed1988

Visceral surface oxygen tension in experimental colitis in the rabbit.

The impairment of bowel healing that is characteristic of inflammatory bowel disease (IBD) is poorly understood. Because bowel healing is related to the adequacy of perfusion in other circumstances, we studied bowel surface oxygen tension (PSO2), which is related to bowel perfusion, in rabbits with IBD. Both cell-mediated (n = 17) and immune complex-mediated (n = 10) colitis caused marked attenuation of colon PSO2. Control (n = 13) left colon PSO2 was 36 +/- 5 (SEM) torr. In mild colitis, left colon PSO2 fell to 11 +/- 5 torr, and in severe colitis it fell to 4 +/- 1 torr (p less than 0.01 for each compared with control). These changes occurred irrespective of the mechanism of induction of colitis. Gastric and small intestinal PSO2 were unaffected. Hepatic and renal PSO2 were decreased in severe colitis only. The presence of decreased PSO2 was a better marker for the presence of IBD than was histologic evaluation. It is suggested that attenuation of PSO2 may be a marker for the physiologic activity of IBD. If this is so, PSO2 may prove a useful adjunct in the operative management of IBD.

Animals↗

PubMed1987

Triple-contrast computed tomography in the evaluation of penetrating posterior abdominal injuries.

Routine exploration of stable patients who have penetrating injuries of the posterior abdomen results in a high rate of unnecessary operation. Prolonged observation, while safe, is expensive and potentially morbid in the event that a retroperitoneal injury has occurred and treatment is delayed. To evaluate these injuries, we have developed and employed a protocol for computed tomographic (CT) scanning of the abdomen employing oral, intravenous, and rectal administration of contrast material to visualize the retroperitoneal contents. Between Jan 1, 1985, and Dec 1, 1986, 40 patients were studied in this manner. In each case, the path of penetration could be determined exactly by tracing the course of air and hematoma through the tissues. All retroperitoneal organs could be evaluated well enough to exclude injuries requiring intervention. The majority of patients showed subcutaneous penetrations only. All six significant intra-abdominal injuries were diagnosed correctly and confirmed at laparotomy. All 34 patients deemed by CT not to have significant injury were observed for 72 hours, and all were discharged uneventfully. Triple-contrast CT appears to be of great value in the triage of penetrating posterior abdominal trauma into operative and nonoperative groups.

Abdominal Injuries↗

PubMed1987

Tissue salvage by mapping of skin surface transcutaneous oxygen tension index.

Healing of both pathologic and surgical wounds is strongly dependent on adequate skin blood flow and oxygenation. The transcutaneous oxygen tension (PtcO2) index (regional PtcO2 index = RPI = limb PtcO2/chest PtcO2) and wound healing were assessed prospectively in 159 wounds in 113 high-risk patients referred for standard noninvasive tests. Patients were managed by referring practitioners on the basis of clinical assessment and standard tests. Treatment was divided into local procedures and amputations. Of 93 local procedures, 48 healed (RPI = 0.72 +/- 0.10 [mean +/- SD]) and 45 failed (RPI = 0.25 +/- 0.12). Of 66 amputations, 45 healed (RPI = 0.64 +/- 0.09) and 21 failed (RPI = 0.28 +/- 0.11). Well-oxygenated skin healed reliably regardless of the cause of the wound. Regional skin oxygenation studies aid rapid diagnosis of ischemia and allow maximal conservation of tissue in limb salvage situations.

Aged↗

PubMed1985

Hypersensitive prostaglandin and thromboxane response to hormones in rabbit colitis.

Inflammation of the colon is associated with increased production of prostaglandins (PG) and thromboxanes (Tx), and these eicosanoids may contribute to the inflammatory, secretory, and motility dysfunctions in colitis. To evaluate the potential role of peptide hormones in the enhanced eicosanoid release, colitis was established in rabbits by a delayed-type hypersensitivity reaction to dinitrochlorobenzene and by an immune-complex-mediated reaction. PG and Tx were identified in the venous effluent of isolated perfused colons by radiochromatography after [14C]arachidonic acid prelabeling, as well as by bioassay, and then quantitated by immunoassay. The two colitis models were morphologically similar. Basal release of PGE2, PGI2, and TxA2 was two- to threefold greater from colitis tissue than from control tissue. Bradykinin (BK) and angiotensin II (ANG II) increased release of 14C-labeled eicosanoids, whereas several gastrointestinal hormones had no effect. In control colons, BK and ANG II increased PGE2 and PGI2 release (by about 2-fold) but did not alter TxA2. In contrast, BK and ANG II markedly exaggerated the release of eicosanoids in colitis. BK increased TxA2 release with 10-ng bolus injections in colitis, but there was no response with up to 10-micrograms bolus injections in control colons. The BK-induced Tx release in colitis was associated with an increase in vascular resistance (measured as perfusion pressure). Infusion of the selective Tx inhibitors dazoxiben and OKY-046 reduced TxB2 release by 96% and blunted the transient rise in perfusion pressure (from 17 +/- 5 to 5 +/- 2 mmHg). Since BK and possibly ANG II are increased at sites of inflammation, the hypersensitive eicosanoid response to these peptides may augment the eicosanoid-mediated manifestations of colitis.

Animals↗

PubMed1984

Superiority of transcutaneous oximetry in noninvasive vascular diagnosis in patients with diabetes.

Transcutaneous oxygen tension Ptco2 is directly related to skin oxygen delivery. Regional transcutaneous oximetry ( RTO ) compares peripheral and truncal (Ptco2), yielding a regional perfusion index indicative of local limb perfusion. The relative diagnostic values of RTO , Doppler ankle-brachial pressure ratio (ABR), pulse volume recording (PVR), and toe pulse reappearance time (PRT/2) were studied in 64 limbs of patients with diabetes. These limbs were clinically classifiable into claudication, rest pain, and gangrene groups. Regional transcutaneous oximetry had a higher diagnostic accuracy than ABR (X2 = 27.47, P less than .001), PVR (X2 = 7.54, P less than .01), and PRT/2 (X2 = 10.99, P less than .001). Regional transcutaneous oximetry was universally applicable and the degree of hypoxia observed correlated with clinical symptoms. Significant hypoxia predicted large-vessel angiographic lesions, many of which were reconstructible . Regional transcutaneous oximetry should be the initial noninvasive test in diabetic peripheral vascular disease.

Aged↗

PubMed1984

The use of surface oximetry to assess bowel viability.

Tissue depends on perfusion, but tissue oxygenation measurements have been impractical. To develop a method for the clinical evaluation of bowel viability, we studied PO2 on the bowel surface (PSO2). The PSO2 was assessed on the stomach and intestine of 11 dogs. Normal small-bowel PSO2 was 44 +/- 11 mm Hg (mean +/- SD). When bowel vasculature was interrupted PSO2 rapidly decreased. Reductions in PSO2 were related to the degree of ischemia produced. Anastomoses were performed on partially devascularized bowel to determine anastomotic viability at various levels of PSO2. The PSO2 measured just prior to anastomosis predicted viability of the anastomoses at 48 hours. Anastomoses below 30% of predevascularization PSO2 necrosed. Between 30% and 50%, one third of anastomoses leaked. At PSO2 values above 50% of initial normal value all anastomoses healed. Surface oximetry allows accurate intraoperative assessment of bowel perfusion.

Animals↗

PubMed1984

Assessment of perfusion in the diabetic foot by regional transcutaneous oximetry.

Regional transcutaneous oximetry is a new, noninvasive diagnostic technique for the investigation of peripheral vascular disease (PVD) that uses differences in limb and trunk transcutaneous PO2 to assess the adequacy of local perfusion. The application of such measurements would be of great importance in diabetes, in which limb ischemia is commonly difficult to assess. A group of diabetic subjects with symptomatic PVD was studied with regional oximetry, Doppler-assisted blood pressure measurements, and arteriography. Doppler studies correlated poorly to symptom grade and angiographic data, while oximetry clearly demonstrated limb hypoxia under the functional conditions appropriate to the patients' clinical symptomatology. The superiority of oximetry to Doppler studies was highly significant (X2 = 12.64, P less than 0.001). Regional transcutaneous oximetry should therefore be the noninvasive diagnostic test of choice in the initial evaluation of the diabetic limb for PVD. Because of its dependence on the adequacy of local oxygenation, transcutaneous oximetry is a powerful tool for investigation of the pathophysiology of PVD and will, in the future, have wide-ranging applications to the diagnosis and therapy of PVD.

Aged↗

PubMed1984

Pathophysiologic classification of peripheral vascular disease by positional changes in regional transcutaneous oxygen tension.

The clinical manifestations and prognosis of peripheral vascular disease (PVD) depend upon the severity of limb hypoxia. Transcutaneous oxygen tension (Ptco2) is related to tissue oxygenation, but limb Ptco2 varies with changes in systemic as well as peripheral oxygen delivery (Do2). Previously we have found that simultaneous assessment of limb and chest Ptco2 yields a ratio, or regional perfusion index (RPI), that is independent of systemic Do2 and accurately reflects the adequacy of limb perfusion. Analysis of segmental limb Ptco2, RPI, and position-induced RPI changes was performed in 24 control limbs and 14 limbs with intermittent claudication (IC), 8 limbs with rest pain (RP), and 7 limbs with gangrene (G). Control limbs had high RPI values that varied little with position. The IC group had modestly decreased RPIs in the supine position, but extremity RPIs decreased markedly during leg elevation. Patients with RP had ischemia while supine, but the RPI improved to nearly normal upon standing. Feet with G were hypoxic even in the standing position. Segmental RPI decreases correlated with the presence of significant arterial lesions. This correlation was unaffected by diabetes. Analysis of regional transcutaneous oximetry allows classification of PVD by quantitative criteria based upon the adequacy of limb perfusion under functional conditions. RPI is characteristically high in normal persons and low in persons with G. Limbs with marginally compensated perfusion may have nearly normal RPI values under some conditions, but typical ischemic changes are elicited by positional change and exercise. The ease of such provocation of RPI decreases constitutes an index of the severity of disease. Such quantitative assessments of limb hypoxia can form the basis for a physiologic approach to arterial reconstruction.

Aged↗

PubMed1983

Use of a transcutaneous PO2 regional perfusion index to quantify tissue perfusion in peripheral vascular disease.

In order to develop transcutaneous oxygen tension (PtcO2) measurements into a practical method for assessing peripheral vascular disease, the relationships between extremity and chest wall PtcO2 were examined in subjects with and without systemic atherosclerotic disease. The ratio of extremity to chest PtcO2, or transcutaneous regional perfusion index (RPI) assessed limb oxygenation more reliably than did direct PtcO2 measurement by obviating the effects of changes in systemic oxygen delivery upon local PtcO2. The authors find that transcutaneous oximetry can be used during treadmill exercise testing and that the RPI is unchanged by exercise in all normal subjects. PtcO2 and RPI were then measured during rest, position change, and exercise testing in patients with intermittent claudication. Whereas normal subjects maintain a constant thigh and calf RPI during exercise, patients with intermittent claudication consistently manifested large decreases in RPI in these areas when they were exercised until symptomatic. The authors find no overlap between the responses of normal subjects and patients with claudication; positive findings are, therefore, highly specific for exercise-induced limb ischemia. Since transcutaneous RPI exercise testing is easily performed and highly reproducible, it is well suited to clinical use in the diagnosis and documentation of intermittent claudication. Furthermore, since limb ischemia can be quantified, this method lends itself both to grading the severity of disease and to evaluating clinical progression of disease. It is suggested that such a quantitative approach to evaluation of intermittent claudication may allow refinement and extension of the indications for operative intervention in patients with intermittent claudication.

Adult↗

PubMed1983

Transcutaneous gas tension monitoring in the management of intraoperative apnea.

Periods of apnea or severe hypoventilation may occur during procedures which involve the airway or during thoracic operations. Routine vital signs and ECG monitoring of these situations are incapable of quantitating the severe tissue hypoxia and acidosis which develop under these circumstances; rather, they only reflect the morbid complications of hypoxia and acidosis (i.e., bradycardia, ectopy, and hypotension). Transcutaneous oxygen and carbon dioxide sensors directly measure tissue gas tensions with a short sensor response time. This report documents the efficacy of transcutaneous gas tension monitoring in the management of these high-risk situations.

Adult↗

PubMed1983

Calcium homeostasis in patients with acute pancreatitis.

Calcium homeostasis was studied serially in six patients admitted to the surgical intensive care unit because of acute pancreatitis. All developed ionized hypocalcemia. Serial assays of serum parathyroid hormone (PTH) revealed a prompt response to this hypocalcemia (1143 +/- 239 versus 574 +/- 24 pg/ml, P less than 0.05). Serum 1,25-dihydroxyvitamin D (1,25(OH)2D) levels rose from 26 +/- 8 to 104 +/- 17 pg/ml (P less than 0.01) in the expected time frame subsequent to the PTH peak, confirming the biologic significance of the PTH increases observed. Despite these significant elevations of PTH and 1,25(OH)2D, the expected prompt return of ionized calcium concentrations to normal levels was not seen. Also, urinary cyclic adenosine monophosphate production was not stimulated. These results suggest an acute functional resistance of bone to physiologic levels of PTH stimulation during the acute phase of pancreatitis. Fluid sequestration and hypovolemia are marked at this time. We suggest that pancreatitic hypocalcemia may occur when oligemic bone cannot respond normally to PTH and 1,25(OH)2D stimulation. As such, it may represent an end organ failure syndrome associated with shock and poor tissue perfusion.

Acute Disease↗

PubMed1982

Use of crystalline hemoglobin as replacement of RBC mass.

Replacement of a circulatory RBC mass was performed isovolemically in experimental dogs using either 7% crystalline hemoglobin solution with a low P50 (the oxygen tension necessary to produce 50% saturation of hemoglobin at pH 7.4 and 37 degrees C) or with an albumin solution. Progressive RBC depletion caused increased cardiac output in both groups. Oxygen delivery was better preserved after using the crystalline hemoglobin solution, and, under conditions of extreme anemia, oxygen transport using this solution enabled dogs to survive the otherwise lethal insult. Although administration of crystalline hemoglobin preserved oxygen transport, oxygen off-loading was at a lower tension because of the lower P50. Decreased mixed venous oxygen tension, which presumably reflects lower tissue oxygen tension, was associated with systemic vasoconstriction. The administration of oxygen-carrying solutions with low P50 values results in a relatively vasoconstricted state. This vascular response is mediated by changes in tissue oxygen tension, rather than by impaired tissue oxygen consumption.

Animals↗

PubMed1982

Hemoglobin solution in the treatment of hemorrhagic shock.

The major physiological effects of hemorrhage are hypovolemia and anemia. The administration of an oxygen-carrying plasma expander, such as crystalline hemoglobin solution (CHb), can restore both of these deficits while avoiding many of the logistical problems entailed in the use of blood. The authors have used Chb to treat severe hypovolemia and anemia in separate canine models and found it to be highly effective. CHb acts as a colloid plasma expander to resuscitate intravascular volume in hypovolemia and supplements oxygen-carrying capacity in anemia. CHb can support oxygen transport essentially in the absence of red blood cells. Hemodynamic responses to low P50 CHb, however, suggest that oxygen offloading at the tissue level is compromised by the high oxygen affinity of unmodified CHb. Whereas such oxygen offloading deficits may be compensated for in the chronic situation, they may be of crucial importance in severe trauma where oxygen transport is often limited by arterial desaturation, low cardiac output, maldistribution of perfusion and interstitial water overload. The development of a lower-affinity CHb is, therefore, of the essence.

Animals↗

PubMed1982