Biomedical subjects

C E Bredenberg

Publications and source records attributed to C E Bredenberg.

At least 37 records · Page 2Linked to original sources

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↗

PubMed1987

Spontaneous dissection of the cervical internal carotid artery: correlation of arteriography, CT, and pathology.

Spontaneous dissection of the internal carotid artery is being recognized as a more frequent cause of acute neurologic deficit, particularly in young persons. Saccular pseudoaneurysm formation may be an associated finding, especially in the presence of tortuosity (coiling) of the cervical internal carotid artery. Of eight patients with nine vessels demonstrating internal carotid artery dissection on arteriography, pseudoaneurysms were found in five arteries. Four of the five pseudoaneurysms occurred in tortuous (coiled) arterial segments. Thin-section contrast-enhanced dynamic incremental CT showed close agreement with the findings on selective arteriography and provided additional information on the presence and configuration of arterial wall thickening as well as the extent of the pseudoaneurysm. Our experience indicates that CT may play an important role in the diagnosis, management, and follow-up of this lesion.

Adult↗

PubMed1986

Multiple malignancies of the lung and head and neck. Second primary tumor or metastasis?

Independent primary cancers of the head and neck and of the lung may be confused with lung metastases from a head and neck tumor. We retrospectively reviewed the cases of 55 patients who had head and neck malignancies and pulmonary lesions. To distinguish between independent primary tumors and lung metastases we applied an algorithm using the following criteria: sequence of appearance of the lesions; tumor histology; radiologic appearance of the lesions; and presence of malignant anterior cervical adenopathy. In this group of 55 patients, 40 were categorized as having independent primary malignancies and 15 were categorized as having pulmonary metastases from the head and neck tumor. In cases in which the origin of the pulmonary lesion is unclear, the patient should be treated as though independent primary malignancies were present since this offers the best chance for cure.

Carcinoma, Squamous Cell↗

PubMed1986

Microvascular membrane permeability in high surface tension pulmonary edema.

Pulmonary edema was induced in dogs by an aerosol of detergent dioctyl sodium sulfosuccinate. The permeability of the pulmonary microvascular membrane was assessed by cannulating an afferent tracheobronchial lymphatic and comparing the lymph-to-plasma total protein concentration (CL/CP) during high lymph flows induced by increasing left atrial (LA) pressure after detergent aerosol. Base-line CL/CP of 0.69 +/- 0.02 fell to 0.55 +/- 0.03 with increased LA pressure alone. CL/CP fell to 0.47 +/- 0.02 when LA pressure was increased following detergent, 0.51 +/- 0.04 following an aerosol of the vehicle in which the detergent was dissolved, and 0.73 +/- 0.10 following intravenous alloxan. In additional animals protein concentration of the airway edema fluid was compared with that of plasma. The ration of protein concentration of airway fluid to plasma was 0.63 +/- 0.08 following detergent aerosol, 0.64 +/- 0.10 following increased LA pressure, and 0.94 +/- 0.09 following administration of alloxan. These data indicate no major increase in pulmonary microvascular permeability following detergent aerosol and support the concept that pulmonary edema is the consequence of reduced interstitial perimicrovascular hydrostatic pressure caused by increased alveolar surface tension.

Animals↗

PubMed1985

High surface tension pulmonary edema induced by detergent aerosol.

The effect of the detergent dioctyl sodium sulfosuccinate on pulmonary extravascular water volume (PEWV) was studied in adult anesthetized mongrel dogs. The detergent was dissolved as a 1% solution in a vehicle of equal volumes of 95% ethanol and normal saline and administered by ultrasonic nebulizer attached to the inspiratory tubing of a piston ventilator. Two hours following detergent aerosol PEWV measured gravimetrically was increased compared with either animals receiving no aerosol or those receiving an aerosol of vehicle alone. Loss of surfactant activity and increased alveolar surface tension were demonstrated by Wilhelmy balance studies of minced lung extracts, by a fall in static compliance, and by evidence of atelectasis and instability noted by gross observation and by in vivo microscopy. No significant changes in colloid oncotic pressure or pulmonary microvascular hydrostatic pressure were observed. These data suggest that pulmonary edema can be induced by increased alveolar surface tension and support the concept that one of the major roles of pulmonary surfactant is to prevent pulmonary edema.

Aerosols↗

PubMed1984

Dependent rubor as a predictor of limb risk in patients with claudication.

We followed up 133 patients with claudication to determine the prognostic value of dependent rubor. Life tables analysis was used, with a threatened limb as the endpoint. A threatened limb was defined as the development of ischemic rest pain, skin ulceration, or gangrene. At four years, the rubor group had a limb-threat incidence of 25%, compared with only 9% in the nonrubor group. While not indicative of imminent limb loss, the presence of dependent rubor defines patients whose limb risk is greater than in those with claudication alone.

Adult↗

PubMed1984

Injuries to arterial branches of the aortic arch.

Exposure of arch branches for repair following trauma can be difficult. Seven patients with blunt injuries and 5 with penetrating injuries underwent repair of the innominate, common carotid and subclavian arteries. Common associated injuries included head injury, hemopneumothorax, lung contusion, long bone fractures and brachial plexus injury. Widened mediastinum was seen in 5 patients. Six patients with innominate, right subclavian and right common carotid injuries were approached through sternotomy with extension into the right side of the neck. Posterolateral thoracotomy was used to reach the proximal left subclavian artery in 2. Combined supra- and infraclavicular incision were utilized for the distal subclavian artery in 4. Eleven patients are alive, one to 7 years after surgery. One died of an unrelated cause. Head injuries complicated the postoperative management in 4 of the 7 patients with blunt trauma. Two patients with brachial plexus injury continued to have neurologic deficits. All arterial repairs have remained patent and there have been no graft infections.

Adolescent↗

PubMed1983

High surface tension pulmonary edema.

Dogs were anesthetized with pentobarbital and placed on a piston ventilator with room air. Ten animals received an endobronchial lavage of normal saline (3 mg/kg). Ten other animals received an endobronchial lavage of the same volume of a nonionic detergent, Tween 20, 5% in saline. Detergent lavage was shown by Wilhelmy balance to increase surface tension of lung extracts. Saline lavage did not alter the surface tension of lung extracts. No significant differences between the groups were noted in cardiac output, left ventricular and diastolic pressure, mean pulmonary artery pressure, or colloid oncotic pressure. Static compliance and arterial PO2 were decreased following detergent lavage. Animals were sacrificed 2 hr after lavage and pulmonary extravascular water volume (PEWV) was measured gravimetrically. Saline-lavaged lungs with normal surface tension had a PEWV of 4.3 ml/g dry lung. Tween-lavaged lungs with increased surface tension had a PEWV of 5.3 ml/g dry lung (P less than 0.005). When the estimated volume of residual lavage solution remaining in the lung parenchyma was subtracted from the total wet lung wt, the corrected PEWV was 3.62 +/- 0.12 ml/g dry lung for saline-lavaged lung and 4.76 +/- 0.19 ml/g dry lung for Tween-lavaged lung. PEWV for 11 control animals ventilated 2 hr without lavage was 3.61 +/- 0.13 ml/g dry lung. It is concluded that, experimentally, high alveolar surface tension can induce pulmonary edema even when pulmonary microvascular hydrostatic and colloid oncotic pressures are normal.

Animals↗