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Biomedical subjects

H J Proctor

Publications and source records attributed to H J Proctor.

At least 37 records · Page 2Linked to original sources
PubMed1983

Effect of hypothermia during hypoxic hypotension on cerebral metabolism.

The beneficial vs deleterious effects of hypothermia superimposed on hypoxia and hypotension have been argued and are clinically important. In this study, cerebral cytochrome a,a3 redox state and the quantity of intracerebral oxygenated hemoglobin (HbO2) were measured continuously and noninvasively in rats subjected to hemorrhagic hypotension (MAP = 30 mm Hg) and hypoxia (F1O2 = 7.5%) utilizing near infrared spectrophotometry. Prior to the experiment the rats were briefly respired on 100% oxygen to establish 100% oxidation of cytochrome a,a3 and hemoglobin, and at the conclusion of the experiment they were respired on 100% nitrogen to establish 100% reduction. Data are reported as percent oxidation within this range at baseline and after 15 and 30 min of hypoxic hypotension. Arterial blood gases were measured. Body temperature as monitored by a rectal probe was altered by placing anesthetized-paralyzed rats inside a circulating water jacket. Three groups of rats were studied: 38, 33, and 22 degrees C. Group III rats had a significantly (P less than 0.01) greater quantity of intracranial HbO2 than group I or II. Since MAP was held constant at 30 mm Hg, we assume this is largely due to the higher (P less than 0.01) arterial PO2 in group III (101.5) compared to group I and II (48.5, 51.3). Both groups II and III had a significantly (P less than 0.01) greater oxidation of cytochrome a,a3 indicating greater oxygen availability for a given metabolic rate. This was associated with improved survival inasmuch as all rats in groups II and III lived, and only one group I rat survived. It can be concluded that, as used in this study, hypothermia is beneficial and deserves further investigation.

Animals↗
PubMed1983

An evaluation of perfluorochemical resuscitation after hypoxic hypotension.

The relative performance of whole blood and saline, a balanced salt-albumin solution, and Fluosol-43 were compared in an experimental animal model of combined hypoxia and hypotension. The test fluids were evaluated in terms of their respective ability to restore mean arterial pressure and provide adequate oxygen to restore and maintain a normal brain cytochrome a,a3 redox state, restore and sustain normal cerebral cortical ATP and creatinine phosphate concentrations (CP), and return cerebral cortical lactate concentrations to normal after the hypoxic-hypotensive period. With regard to ATP, CP, lactate, and cytochrome a,a3, all three test fluids performed equally well inasmuch as there were no significant differences between groups. None of the test regimens resulted in normal ATP concentration post-hypoxic hypotension. Although CP concentrations were lower than baseline after resuscitation, the difference was not statistically significant. Fluosol-43 resuscitation resulted in a significantly higher (p less than 0.05) mean arterial pressure by 120 minutes post-resuscitation. It was concluded that Fluosol-43 is an acceptable resuscitative fluid, most beneficial at extremely low hematocrits, but that selection of Fluosol-43 over balanced salt-albumin could not be supported when post-resuscitation hematocrits were in the 20 to 25% range.

Adenosine Triphosphate↗
PubMed1983

Surgery for chronic pancreatitis: the tailored approach.

Considerable controversy exists regarding the optimal method of surgical relief of the pain of chronic pancreatitis. We previously made a retrospective study of 49 patients with chronic pancreatitis who were operated upon only for relief of pain. Those results indicated that patients who had an internal decompression had lower mortality, less morbidity, less postoperative pancreatic insufficiency, and better relief of pain (88% vs 76% improved). Since then, we have prospectively determined the operative treatment based upon the criteria outlined in that previous report. Seventeen patients had 19 operations (12 resections, seven internal drainage procedures). The patients' ages, duration of symptoms, and sex distribution are similar. Eight-five percent of patients with internal decompression had good to excellent relief of pain vs 60% of patients with resection. Pancreatic insufficiency occurred in 70% of patients who had resection and in only 14% of those who had drainage. Forty percent of patients who had resection had mild to severe postoperative morbidity vs 14% of those who had drainage. There was one postoperative death in the resection group. These preliminary results indicate that internal decompression in properly selected patients can provide superior relief of pain, with lower mortality, less morbidity, and less pancreatic insufficiency.

Adult↗
PubMed1983

ATP-MgCl2 treatment prior to hypoxic-hypotension.

We have previously implicated uncoupling of oxidative phosphorylation and the associated decreased concentrations of tissue adenosine triphosphate (ATP) in the liver and brain as major factors contributing to death after hypoxia and hypotension. To determine if intravenously administered ATP-MgCl2 complex would result in increased liver and/or brain concentration of ATP, rats were pretreated with intravenous ATP-MgCl2 prior to exposing them to hypoxic-hypotensive stress. In this preliminary work, pretreatment was selected based on the premise that such an experimental design was most apt to demonstrate an effect if such existed. Baseline cerebral cortical and liver ATP and lactate concentrations were obtained immediately after the intravenous infusion of either saline (control group) or ATP-MgCl2 (treated group). ATP and lactate concentrations were again determined after 30 min hypoxic-hypotension and 20 min after resuscitation. ATP-MgCl2 pretreatment resulted in a modest increase in hepatic ATP concentration when measured after 30 min of hypoxic-hypotension. This increase was not evident 20 min later. No increases in cerebral ATP concentrations were noted at any sample time after ATP-MgCl2 pretreatment.

Adenosine Triphosphate↗
PubMed1982

Exchange transfusion with Fluosol 43: in vivo assessment of cerebral cytochrome c oxidase redox state.

Rats were serially exchange transfused to hematocrits less than 2% (50-cc exchange) with either Krebs-Henseleit-albumin (KHA) solution or Fluosol-43 (F-43). Reflectance spectrophotometry was employed to monitor cerebral cytochrome c oxidase redox states. Determination of mean arterial pressure (MAP), arterial and venous oxygen content difference (A-VO2), and cerebral cortical ATP and lactate concentrations were also made. As hemodilution progressed, neither solution provided normal quantities of oxygen as evaluated by the cytochrome c oxidase redox state and a decrease in A-VO2 difference, although F-43 was significantly (p less than 0.01) better than KHA in terms of cytochrome c oxidase redox state as well as maintenance of MAP. There was no significant difference between the two test solutions in terms of cortical ATP and lactate.

Adenosine Triphosphate↗
PubMed1982

Effect of intravenous epinephrine on cerebral cortical blood flow, oxygen tension, and high-energy phosphate metabolism after hypoxic hypotension.

An experimental model was examined in which rats were subjected to 30 minutes of hemorrhagic hypotension and hypoxia. In addition to resuscitation by infusion of blood and saline and increasing the fraction of inspired oxygen (FIO2), the possible beneficial effects of including intravenous epinephrine as part of the resuscitative regimen were studied. Mean arterial pressure, cortical microflow, and brain tissue oxygen tension were increased after epinephrine (P less than 0.05). Cortical ATP concentration was decreased after hypoxic hypotension and failed to improve after epinephrine.

Adenosine Diphosphate↗
PubMed1981

Recanalization of a saphenous vein interposition venous graft.

A patient is reported with successful clinical recanalization of a thrombosed saphenous vein interposition graft in the superficial femoral vein after civilian injury. Primary repair of venous injuries may prevent both initial acute venous hypertension as well as the development of chronic venous insufficiency.

Adult↗
PubMed1981

Surgical treatment of pancreatic carcinoma.

We reviewed 75 patients operated on for carcinoma of the pancreas during the period 1973 to 1978. The role of surgery was examined in terms of contributing toward diagnosis, palliation, and cure. Computerized tomography, ultrasonography, upper gastrointestinal series, and arteriography were used to determine the presence or absence of a pancreatic mass. Arteriography and CT scanning were very helpful. Histologic confirmation was most often provided in conjunction with celiotomy. Endoscopy with cytology and percutaneous needle biopsy was quite specific but was rarely done. Palliative decompression of the biliary tree was done in 63% and biopsy alone in 21%, with a collective morbidity of 20% and a mortality of 3%. Potentially curative resection was done in only 8% with no immediate postoperative deaths. Although pancreaticoduodenectomy will continue to offer the only chance of cure in small numbers of patients, it is evident the present role of surgery is largely for diagnosis and palliation. In view of the mortality and morbidity of operation, increased emphasis should be placed on noninvasive diagnostic tests (CT scan, endoscopy with cytology, and direct needle biopsy). The future role of surgical reduction of the tumor mass in conjunction with adjuvant therapy is at present ill defined.

Diagnostic Errors↗
PubMed1981

Brain neurotransmitter and high-energy phosphate concentration after combined hypoxia and hypotension.

Previous work by the authors has established decreased brain ATP concentration after a combined hypoxic-hypotensive episode. This study was undertaken to determine what changes, if any, occur in brain norepinephrine (NE), dopamine (DA), and serotonin (5HT) concentration in association with hypoxia and hypotension, and to correlate any observed changes with simultaneously measured ATP concentrations. Rats were subjected to a 30-minute period of hypoxia (F102 = 0.075) and hemorrhagic hypotension (MAP = 30 mm Hg) and then resuscitated. Significant increases (P less than .05) in cortical 5HT were observed at a time when ATP concentration was significantly (P less than .005) reduced. Additional experiments were conducted on rats depleted of 5HT by prior treatment with 5,7-dihydroxytryptamine. Equal decreases in ATP concentration were measured, and the cardiovascular response to hypoxic hypotension in 5HT-depleted rats was similar to that in 5HT-intact rats. We conclude that the increased 5HT after hypoxic hypotension does not cause the decreased ATP concentration, nor does 5HT play a major role in cardiovascular homeostasis under the conditions of this experiment.

Adenosine Triphosphate↗
PubMed1980

Emergent or elective operation for symptomatic abdominal aortic aneurysm.

The patient with the symptomatic abdominal aortic aneurysm (AAA) presents a management dilemma, ie, emergent, urgent, or elective operation. The mortality for 38 patients with a ruptured AAA prior to 1972 was 61%. That year, a policy of immediate operation was instituted for patients with symptoms that might be referable to a ruptured AAA. It is concluded that an immediate operation on the patient with a symptomatic but intact AAA resulted in an excessively high mortality. Thus, the indications for an immediate operation on these patients should be based on clinical judgment; attempting to differentiate between the patient with the ruptured and the patient with the intact aneurysm. Hemodynamic data (blood pressure hematocrit reading) suggesting a decrease in blood volume dictate an immediate operation. An urgent operation on the well-prepared patient should be performed on all patients with a symptomatic aneurysm in which the clinical and hemodynamic findings do not suggest that it has ruptured.

Aged↗
PubMed1980

The effect of glucagon on hepatic cellular energetics during a low flow state.

An investigation of the effect of glucagon on liver high energy phosphate concentration during a low flow state is presented. Two groups of dogs were subjected to a 120-minute period of hemorrhagic hypotension followed by reinfusion of shed blood plus additional normal saline to restore the central venous pressure to 10 cm H2O. One group received glucagon intravenously in addition. Despite a significant increase in portal flow and oxygen delivery and a significant increase in liver glucose associated with glucagon administration, there was significant impairment in the ability of the liver to regenerate adenosine triphosphate (ATP). Evidence is presented to show the decreased ATP concentration was not related to hepatic blood flow, but was presumably due to increased catabolism.

Adenosine Triphosphate↗
PubMed1979

Extracorporeal membrane oxygenation in severe acute respiratory failure. A randomized prospective study.

Nine medical centers collaborated in a prospective randomized study to evaluate prolonged extracorporeal membrane oxygenation (ECMO) as a therapy for severe acute respiratory failure (ARF). Ninety adult patients were selected by common criteria of arterial hypoxemia and treated with either conventional mechanical ventilation (48 patients) or mechanical ventilation supplemented with partial venoarterial bypass (42 patients). Four patients in each group survived. The majority of patients suffered acute bacterial or viral pneumonia (57%). All nine patients with pulmonary embolism and six patients with posttraumatic acute respiratory failure died. The majority of patients died of progressive reduction of transpulmonary gas exchange and decreased compliance due to diffuse pulmonary inflammation, necrosis, and fibrosis. We conclude that ECMO can support respiratory gas exchange but did not increase the probability of long-term survival in patients with severe ARF.

Acute Disease↗
PubMed1979

Surgery for chronic pancreatitis. Drainage versus resection.

A retrospective study of 49 patients with chronic obstructive and chronic calcific pancreatitis is presented. All patients were operated upon and underwent either a partial pancreatectomy or internal drainage of the ductal system into a Roux-en-Y loop of jejunum. The criteria for selection of operation are discussed, and the follow-up of the two operative groups is given. In patients selected as described, internal drainage provided better relief of pain and was accomplished with a lower operative mortality and morbidity and with less postoperative pancreatic insufficiency.

Adult↗
PubMed1979

Effects of hypoxia and hypotension on oxygen delivery in the brain.

Failure of microvascular re-perfusion, no reflow, of the brain after a period of ischemia has been proposed as the etiology of the cerebral dysfunction frequently seen in patients after resuscitation from hemorrhagic shock. For this investigation rats were stressed by subjecting them to a period of combined hypoxia and hypotension followed by resuscitation. Micro-oxygen electrodes measured brain oxygen tension, thus allowing an assessment of the distribution of cerebral blood flow, during stress and after resuscitation. After resuscitation, a hyperemic response was noted, followed by gradual return of some areas of the brain to normal perfusion, while other areas remained hyperemic for at least 2 hours post-resuscitation. On the basis of these results there appears to be no support for the no-reflow hypothesis. These data imply that therapeutic modalities aimed at increasing cerebral blood flow and oxygenation in the post-resuscitation period are insufficient in themselves for improved survival of patients sustaining a hypotensive, hypoxic episode.

Animals↗
PubMed1979

Pancreatic and duodenal injuries: morbidity and mortality of surgical management.

A retrospective review of pancreatic injury is presented. Twenty-five cases in which the pancreatic injury was either the sole or major injury were selected from over 100 cases of pancreatic injury admitted during the period 1970 to 1977. Eight pancreatic injuries resulted from blunt trauma and 17 from penetrating trauma. Two methods of treatment were compared, drainage alone versus duodenal diverticularization and/or distal resection. There were no deaths. Of the 15 patients treated by drainage alone, 14 (93%) developed postoperative complications, as compared to 20% (two of ten patients) treated by diverticularization and/or distal resection.

Drainage↗