Biomedical subjects

C E Bredenberg

Publications and source records attributed to C E Bredenberg.

At least 19 recordsLinked to original sources

PubMed1995

Should percutaneous transluminal renal artery angioplasty be applied to ostial renal artery atherosclerosis?

PURPOSE: The purpose of this study was to review the results of percutaneous transluminal renal artery angioplasty (PTRA) in patients with atherosclerosis to assess safety, anatomic and functional outcome, and differences in outcome between ostial and nonostial lesions. METHODS: We used retrospective review of 52 consecutive patients who had undergone attempted PTRA for renal artery atherosclerosis during the calendar years 1987 to 1992. RESULTS: Fifty-two patients had 60 renal arteries on whom PTRA was attempted. The mean age was 68 years. Atherosclerosis was generalized in 81% of the patients. The indication for angioplasty was salvage of functioning renal parenchyma in 81% of patients. Eight patients were undergoing dialysis at the time of attempted PTRA. Five arteries (8%) could not be dilated. There were one cardiac death and two arterial complications requiring surgery within 30 days. Thirty-five percent of patients with available angiograms had an anatomic improvement above a threshold of one stenotic group (30% to 40% diameter improvement), with residual stenosis of less than 50%. Half of patients treated for hypertension had improvement in their hypertension. Overall, there was no change in creatinine levels before and after the procedure. Four of eight patients undergoing dialysis at the time of PTRA were able to discontinue dialysis during follow-up. Four patients (11%) required surgical bypass and five patients (14%) required chronic dialysis during follow-up. CONCLUSIONS: Modest success at low risk can be expected from PTRA in a group of patients with severe atherosclerosis. No significant difference in results between ostial and nonostial lesions was noted.

Adult↗

PubMed1994

Unilateral smoke inhalation increases pulmonary blood flow to the injured lung.

Smoke inhalation (SI) affects the homogeneity of lung perfusion possibly by increasing alveolar surface tension. Anesthetized dogs (n = 8) were ventilated with a tracheal divider and a dual ventilator. One lung (left or right) was exposed to 5 minutes of SI while the other remained on room air. Total pulmonary blood flow (cardiac output) was measured by thermal dilution and left lung blood flow was measured with an ultrasonic flow probe. Since SI is associated with elevation of alveolar surface tension (AST), we studied a second group of dogs (n = 6) in which AST was increased in one lung with aerosolized dioctyl sodium sulfosuccinate (OT). The OT elevates AST without otherwise damaging the lung. Unilateral SI resulted in systemic hypoxemia (Pao2 fell from 91 +/- 6 to 55 +/- 4 mm Hg) and increased venous admixture (9 +/- 2% to 29 +/- 4%) both of which remained different from baseline values (p < 0.05) for 2 hours. Blood flow to the smoke exposed lung increased gradually and became significantly larger than that to the contralateral normal lung 2 hours following inhalation (smoke lung = 64% +/- 6% and normal lung = 36% +/- 6% of total blood flow). Following smoke exposure, pulmonary vascular resistance (PVR) increased with time in the unexposed normal lung (baseline = 8.7 +/- 1.4; 2 hours post smoke = 22.6 +/- 7.9 mm Hg/L/min, p < 0.05); PVR did not change in the smoke injured lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

The neurovascular outcome of scapulothoracic dissociation.

PURPOSE: The purpose of this study was to define the role of acute revascularization in the management of scapulothoracic dissociation (SD), a rare injury of the upper extremity in which severe traction to the shoulder girdle results in combined arterial, brachial plexus, and musculoskeletal injury. METHODS: The results of a retrospective study of 11 patients with SD who were compared with 41 patients from the literature are presented. RESULTS: All 11 patients were involved in high-speed accidents. All patients had chest wall hematoma, absent radial pulse, and complete brachial plexus palsy. All patients had subclavian or axillary occlusion shown by angiography; one patient with simultaneous brachial artery injury had limb-threatening ischemia. No patient had active bleeding from the injured artery. Six limbs were revascularized, five were not. All five non-revascularized limbs remained viable. No patient had delayed hemorrhage. No patient had significant neurologic recovery; all limbs remained insensate and functionless. Two viable arms underwent late amputation because of neurologic dysfunction. CONCLUSION: The infrequent occurrence of delayed hemorrhage and limb-threatening ischemia and the dismal functional outcome of the brachial plexus injury suggest a conservative policy toward revascularization for the arterial injury in SD.

Arm↗

PubMed1992

Changing patterns in surgery for chronic renal artery occlusive diseases.

We report 66 patients undergoing 69 operations for chronic renal artery occlusive diseases operated on at two institutions between January 1985 and June 1990. Etiology was atherosclerosis in 59 patients (90%); fibromuscular disease in four (6%), and three children with nonfibromuscular disease stenosis (4%). Atherosclerosis was local in 10 and generalized in 49 (83% of all patients). Fifty operations (72%) were for salvage of renal function. Average serum creatinine was 2.3 mg/dl and was elevated in 46 patients (70%). Donor arteries for reconstruction were aorta 20 (29%), aortic graft 16 (23%), and other abdominal arteries 33 (48%). Twenty-one patients had concomitant vascular procedures including 16 aortic replacements. The two operative deaths (3%) followed aortic replacements. Three grafts (4%) occluded before discharge from the hospital. Eighty-six percent of patients undergoing renal salvage avoided long-term dialysis. In past decades fibromuscular disease and localized atherosclerosis were the most frequent renal artery occlusive diseases undergoing surgery, hypertension was the predominant indication, and the most frequent operation was aortorenal bypass. As a result of improved pharmacologic management of hypertension and the development of percutaneous transluminal dilation, most patients in this series had far advanced generalized atherosclerosis, and renal salvage was the most frequent indication for operation. As a consequence of the severity of the atherosclerosis, 48% of operations avoided the aorta, 23% replaced the aorta, and aortorenal bypass was used in only 29%.

Angioplasty, Balloon↗

PubMed1991

Blunt trauma to the carotid arteries.

Blunt carotid artery trauma is an uncommon but potentially dangerous clinical entity. We report eight patients from a 10-year interval who sustained blunt injuries to the carotid arteries. Six of eight patients suffered a hyperextension injury or had a cervical spine fracture or both. Arteriography revealed four arterial dissections and four thrombotic occlusions. Two asymptomatic common carotid artery occlusions and one dissection with transient ischemic attacks had successful arterial reconstructions. Five patients were treated nonoperatively: three internal carotid artery dissections with minor or no neurologic deficit; one asymptomatic thrombosis; and one internal carotid artery thrombosis with a major fixed neurologic deficit that did not improve. No patient died, and seven of eight made a complete neurologic recovery or remained asymptomatic. The diagnosis of blunt carotid artery injuries should be suspected in patients with neck hyperextension injuries or with cervical spine fractures as well as in patients with neurologic deficits not explained by intracranial trauma. Duplex scanning may be a useful noninvasive study. Surgery is indicated for selected patients with accessible lesions who have minor or no neurologic deficits. Asymptomatic patients with small intimal flaps or dissections may be successfully treated nonoperatively.

Adolescent↗

PubMed1990

Graft geometry and venous intimal-medial hyperplasia in arteriovenous loop grafts.

This study explores graft geometry and hemodynamics in a reproducible canine arteriovenous loop graft model of intimal-medial hyperplasia. Untapered 6 mm diameter polytetrafluoroethylene grafts (n = 10) were paired with 4 to 7 mm taper (n = 5) or 7 to 4 mm taper (n = 5) grafts for a 12-week period. Several hemodynamic variables were assessed at multiple locations, and venous intimal-medial thickness was measured at locations corresponding to the hemodynamic measurements. Color Doppler imaging demonstrated energy transfer out of the vessel in the form of perivascular tissue vibration. This was quantitated by the distance required for Doppler signal attenuation or volume of the detected vibration signal. Differences among graft types were noted for pressure, flow velocity, tissue vibration, and venous intimal-medial thickness. Hyperplasia was significantly decreased in 4 to 7 mm taper grafts. Stepwise deletion regression indicated volume of the vibration signal had a better correlation with venous intimal-medial thickness than any other variable (r 0.9, p less than 0.001). We conclude that graft geometry can have a significant impact on hemodynamic factors and venous intimal-medial hyperplasia in arteriovenous loop grafts. Flow disturbances appear to cause energy transfer through the vessel wall and into perivascular tissue. Kinetic energy transfer in the form of perivascular tissue vibration was quantitated in vivo and correlates strongly with venous intimal-medial thickness.

Animals↗

PubMed1990

Positive end-expiratory pressure accelerates lung water accumulation in high surface tension edema.

The effect of positive end expiratory pressure (PEEP) on the rate of lung water accumulation with high surface tension pulmonary edema was examined. Alveolar surface tension was elevated by inhalation of 15 mg/kg of the aerosolized detergent dioctyl sodium sulfosuccinate (OT). Hemodynamic measurements, blood gases, and colloid oncotic pressures were recorded in anesthesized dogs for 2 hours after surfactant displacement and elevation of PEEP to 10 cm H2O pressure (group II; n = 10). These data were compared with those of an identical protocol that used only 5 cm H2O PEEP (group I; n = 10). Pulmonary extravascular water volume (PEWV) was measured gravimetrically at the end of the experiment. OT inhalation resulted in an immediate fall in Pao2 and rise in venous admixture (QVa/QT), with little change in colloid oncotic pressure or left atrial pressure. In group I, Pao2 and QVa/QT did not improve significantly over 2 hours, whereas both returned to near baseline in group II. PEWV was elevated in group I compared with normal PEWV (historic controls; n = 11) (6.1 +/- 0.07 - 3.6 +/- 0.01 ml/gm dry lung; p less than 0.01); however, PEWV in group II (9.1 +/- 1.0 ml/gm dry lung; p less than 0.01) was greater than in both group I and historic controls. These data indicate that high alveolar surface tension induces pulmonary edema and PEEP accelerates this edema formation.

Animals↗

PubMed1989

Beneficial effects of banding on venous intimal-medial hyperplasia in arteriovenous loop grafts.

Local hemodynamics were modified in a canine arteriovenous loop graft model by placing a flow-limiting band on femoral polytetrafluoroethylene (PTFE) grafts. Banded and unbanded grafts were implanted in a paired fashion. Hemodynamic studies included Reynolds number and phonoangiography as measures of turbulence. Intimal-medial thickness was measured 8 weeks after implantation. Reduction of the volumetric flow rate by 50 percent resulted in significant changes in flow velocity, flow pulsatility, pressure, and turbulence at the venous anastomosis. Hyperplastic lesions developed in a reproducible manner at the venous anastomosis of the unbanded but not the banded grafts, as evidenced by combined intimal-medial thickness measurements: unbanded grafts 0.68 +/- 0.13 mm (p less than 0.01 versus control), banded grafts 0.25 +/- 0.03 mm (p greater than 0.05 versus control). Stepwise regression analysis indicated Reynolds number had the best correlation with the development of hyperplasia (r = 0.915, p less than 0.005), this being the first time this correlation has been quantitatively determined. We conclude that flow disturbance or turbulence is a major factor in the development of venous intimal-medial hyperplasia in arteriovenous loop grafts.

Animals↗

PubMed1989

Blunt injuries to the aortic arch vessels.

Thirty patients with 33 vascular injuries from blunt trauma to the brachiocephalic branches of the aortic arch are reported. To our knowledge, this is the largest series reported to date of blunt injuries to these vessels. Mechanisms of injury included deceleration, traction, and crush. Half of the injured vessels were the innominate artery, and a quarter each were the common carotid and subclavian arteries. Common associated injuries were head injuries, hemopneumothorax, lung contusion, long bone fractures, and brachioplexus injuries. Widened mediastinum and extrapleural hematoma were common radiographic findings, and aortic rupture was frequently suspected. Angiography was performed in all patients to identify precisely the nature and site of the injury. Surgical approaches varied with the anatomical site of the injury and required consideration of vascular control in chest, neck, and upper extremity. Twenty-seven patients are alive 6 months to 10 years after injury. Eighteen of 20 vascular reconstructions were patent at follow-up. No patient with brachioplexus injury had return of neurological function.

Adolescent↗

PubMed1989

Management of suspected mycotic suprarenal aortic aneurysm.

Mycotic aortic aneurysm is an uncommonly encountered entity. The diagnosis and management are challenging problems. Involvement of the visceral aorta creates additional problems in management. Experience with a patient having this diagnosis and the dilemma in treatment forms the basis of this report.

Aged↗

PubMed1989

Posterolateral exposure for renal artery reconstruction.

Anterior approaches to the renal arteries are complicated by the intervening renal veins, inferior vena cava, and abdominal viscera. We describe techniques of direct posterolateral access to both right and left renal arteries by use of an extended retroperitoneal exposure. This approach allows for grafting from the aorta or iliac artery on either side and is particularly suitable on the left side for direct retropancreatic splenorenal artery anastomosis, which is described in detail. It is also useful for distal reconstruction of branch renal arteries, renal artery embolectomy, and autotransplantation "bench surgery." We have used this approach in 28 patients with no operative deaths and two reconstructive occlusions.

Humans↗

PubMed1989

Operative angiography by intraarterial digital subtraction angiography: a new technique for quality control of carotid endarterectomy.

Fifty patients who had carotid bifurcation endarterectomy as their sole surgical procedure underwent intraoperative completion angiography by means of portable intraarterial digital subtraction angiography. All had subsequent intravenous digital subtraction angiography or duplex scanning during early follow-up. After the endarterectomy site was closed and before the wound was closed, 6 to 8 ml of contrast was injected through a 21-gauge needle while fluoroscopy was performed with a conventional C-arm. The C-arm was coupled to a Quantel IDIS Mobile Digital Subtraction Angiogram Unit (Quantel Medical Products Group, Clemmons, N.C.) for image enhancement and immediate playback. There were no postoperative deaths or neurologic complications. Abnormal radiographic results led to reopening of endarterectomy sites in eight patients, which resulted in successful correction of the defects. There was a single asymptomatic occlusion of the internal carotid artery at 3 weeks in the patient with the only false-negative result on the completion study. Intraarterial digital subtraction angiography is a safe and useful technique for intraoperative quality control of carotid endarterectomy. It provides visual images that can be easily repeated in several projections, uses small volumes of contrast, and has no timing requirements for filming and injecting.

Carotid Artery Diseases↗

PubMed1989

Wood smoke inhalation increases pulmonary microvascular permeability.

The effect of wood smoke inhalation (SI) on pulmonary vascular permeability was studied in open-chested, anesthetized dogs. Animals were divided into two groups. A prenodal lymphatic vessel was cannulated in group I (n = 7), and baseline (BL) lung lymph flow (QL) and lymph (CL) and plasma (CP) protein concentrations were measured. The animals' lungs were then ventilated with wood smoke for 5 minutes. Left atrial pressure (Pla) was increased above baseline (mean 16.7 +/- 2.2 mm Hg), and the ratio of CL to CP was used to assess endothelial permeability at high lymph flows. There was little change in either QL (BL: 27 +/- 9; SI: 27 +/- 5 microliters/min) or CL/CP (BL: 0.76 +/- 0.03; SI: 0.74 +/- 0.02) after SI at normal Pla. Elevation of Pla caused a significant increase in QL (136 +/- 15 microliters/min), but CL/CP (0.67 +/- 0.02) failed to decrease significantly at high lymph flows. In group II (n = 15) total protein concentration of airway fluid was compared with that of plasma after smoke inhalation, intravenous alloxan, and increased Pla. The ratio of protein concentration in airway fluid to plasma after SI (0.70 +/- 0.07) was greater than that obtained with increased Pla (0.64 +/- 0.07) but less than that after alloxan (0.85 +/- 0.04). These data indicate that SI in the dog results in a moderate increase in pulmonary vascular permeability that is less severe than that induced by alloxan.

Animals↗

PubMed1988

Atraumatic control in calcified arteries.

We have attempted distal saphenous vein bypasses for limb salvage in increasingly difficult situations. Severe calcification in the recipient artery makes vascular control and anastomosis troublesome. An atraumatic method of intraluminal control, which has been of aid in this situation, is described.

Anastomosis, Surgical↗

PubMed1988

Effect of increased alveolar surface tension on segmental pulmonary vascular resistance.

The site of change in pulmonary vascular resistance (PVR) after surfactant displacement with the detergent diocytl sodium sulfosuccinate (OT) was studied in the isolated canine left lower lobe preparation. Changes in PVR were assessed using the arterial and venous occlusion technique and the vascular pressure-flow relationship. Changes in alveolar surface tension were confirmed from measurements of pulmonary compliance as well as from measurements of surface tension of extracts from lung homogenates. After surfactant depletion (the perfusion rate constant) the total pressure gradient (delta PT) across the lobe increased from 13.4 +/- 1 to 17.1 +/- 0.8 mmHg. This increase in delta PT was associated with a significant increase in the arterial and venous gradients (3.7 +/- 0.3 to 4.9 +/- 0.4 and 5.7 +/- 0.5 to 9.4 +/- 0.6 mmHg, respectively) and a decrease in middle pressure gradient (4.1 +/- 0.8 to 2.9 +/- 0.6 mmHg). The vascular pressure-flow relationship supported these findings and showed that the mean slope increased by 52% (P less than 0.05), whereas the pressure intercept decreased slightly but not significantly (3.7 +/- 0.7 to 3.2 +/- 0.8 mmHg). These results suggest that the resistance of arteries and veins increases, whereas the resistance of the middle segment decreases after surfactant depletion. These effects were apparently due to surface tension that acts directly on the capillary wall. Direct visualization of subpleural capillaries supported the notion that capillaries become distended and recruited as alveolar surface tension increases. In the normal lung (perfused at constant-flow rate) changes in alveolar pressure (Palv) were transmitted fully to the capillaries as suggested by equal changes in pulmonary arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Effect of positive end-expiratory pressure on alveolar capillary perfusion.

Positive end-expiratory pressure (PEEP) increases arterial carbon dioxide tension and alveolar dead space by reducing alveolar capillary perfusion. The two likely mechanisms by which PEEP reduces alveolar capillary perfusion are reduction of cardiac output or compression of pulmonary capillaries within interalveolar septa, or both mechanisms. This study attempts to quantitate the impact of each of these mechanisms on alveolar capillary perfusion in anesthetized dogs by restoring cardiac output to baseline values with dextran 70 infusion after application of 15 cm H2O PEEP. Alveolar capillary perfusion was assessed directly through the visceral pleura by in vivo photomicroscopy. PEEP resulted in a fall in cardiac output and alveolar capillary perfusion with a concomitant rise in alveolar dead space-tidal volume ratio and arterial carbon dioxide tension. Infusion of dextran 70 returned the cardiac output to baseline levels but only slightly increased alveolar capillary perfusion. Both dead space/tidal volume ratio and arterial carbon dioxide tension remained significantly elevated with PEEP even with normal cardiac output. Microscopically, alveolar capillaries appeared compressed and flattened by PEEP, which indicated a mechanical interruption of blood flow. Extra-alveolar vessels remained perfused with PEEP. PEEP increased dead space/tidal volume ratio 36%; restoration of cardiac output reduced dead space/tidal volume ratio only 7% and did not return alveolar capillary perfusion to baseline levels. These data indicate that most of the reduced alveolar perfusion with PEEP results from direct compression of alveolar capillaries and not from reduced cardiac output.

Animals↗

PubMed1987

Palliation of inoperable esophageal carcinoma. Therapeutic endoscopy as an adjunct to combined chemotherapy and radiotherapy.

The combined regimen of irradiation and chemotherapy has been successfully used as a preoperative measure to improve the cure rate for squamous cell carcinoma of the esophagus. In the nonresectable patient, we have seen response to this regimen in the form of conversion of the neoplastic stricture into a fibrous one. Dysphagia remained unchanged due to the persistence of a stricture. In this situation, therapeutic endoscopy can be highly effective for relief of dysphagia, as illustrated by a case report, and is proposed as the palliative procedure of choice when the patient has shown response to combined chemotherapy and radiotherapy.

Carcinoma, Squamous Cell↗

PubMed1987

Surfactant displacement by meconium free fatty acids: an alternative explanation for atelectasis in meconium aspiration syndrome.

Meconium, an ether extract of meconium, and the major free fatty acids of meconium (palmitic, stearic, and oleic acids) were all found to increase the surface tension minimum of dog lung extract in a Wilhelmy balance. Each of these fractions was instilled into the lungs of dogs (15 experimental, eight saline solution controls), and cardiac output, venous and arterial blood gases, pulmonary, atrial, and systemic pressures, airway pressure, and static lung compliance were serially monitored for 2 hours. Mean airway pressure increased and static lung compliance decreased significantly in all of the experimental groups. Although arterial pH and PaCO2 and the various hemodynamic measurements did not change during the experiment, PaO2 decreased significantly and did not return to baseline in all experimental groups. Extracts from atelectatic portions of experimental dog lung had a surface tension minimum of greater than 20 dynes/cm, whereas airway foam had a surface tension minimum of less than 10 dynes/cm, suggesting that the free fatty acids of meconium are able to strip surfactant from the alveoli.

Animals↗