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Biomedical subjects

W H Snyder

Publications and source records attributed to W H Snyder.

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

Mortality and renal salvage after renovascular trauma. A review of 94 patients treated in a 20 year period.

Ninety-four patients with 96 renovascular injuries underwent operations over a 20 year period. Forty-nine patients had renal artery injury, 45 had isolated venous injury, and 33 had both vessels injured. Arterial revascularization succeeded in four patients, failed in five, and the results were not documented in three. Revascularization of acute renal artery thromboses was unsuccessful. Isolated renal vein injuries were repaired in 28 patients. The mortality rate was 37 percent for renal artery injuries and 28 percent for isolated renal vein injuries, despite the frequent choice of nephrectomy instead of reconstruction in unstable patients. Renal salvage was accomplished in 10 percent of patients with renal artery injury and in 51 percent of patients with isolated renal vein injury. Renal salvage is not often feasible in patients with renal arterial injuries because of associated renal vein injuries. The success of revascularization of traumatically occluded renal arteries is low and should probably be attempted only in unusual circumstances, such as bilateral injuries. Most isolated renal vein injuries are repairable, and reconstruction should be attempted in stable patients.

Adolescent↗
PubMed1983

Arterial injuries below the knee: fifty-one patients with 82 injuries.

Clinical features of tibial and peroneal artery injuries are characterized in a review of 51 patients with 82 injured arteries. Injuries were penetrating in 34 (67%) patients and blunt in 17 (33%). Physical findings suggested arterial injuries in 42 (82%) patients, but nine had no signs of vascular trauma. Nineteen patients with no palpable distal pulses had average preoperative delays of nearly 5 hours, suggesting a lack of appreciation for the morbid potential of these injuries. Operations included ligations of single-vessel injuries and arterial reconstructions in the 21 (41%) patients with two or more injured vessels. Amputations were necessary in eight (16%) patients. Limb loss was more frequent with blunt trauma (23%), shotgun wounds (33%), initial absent pulses (32%), and three injured vessels (60%). The frequency of limb loss with these injuries emphasizes the importance of early diagnosis, expedient operation, and thorough revascularization.

Adolescent↗
PubMed1982

Diffusion in the vicinity of standard-design nuclear power plants--I. Wind-tunnel evaluation of diffusive characteristics of a simulated suburban neutral atmospheric boundary layer.

A large meteorological wind tunnel was used to simulate a suburban atmospheric boundary layer. The model-prototype scale was 1:300 and the roughness length was approximately 1.0 m full scale. The model boundary layer simulated full scale dispersion from ground-level and elevated release points over surfaces of comparable roughness length. This information should prove useful in a variety of transport and diffusion studies over short to moderate downwind distances. It will be used in Part II as the baseline data set with which to compare diffusion downwind of standard-design nuclear power plants.

Air Pollution, Radioactive↗
PubMed1982

Diffusion in the vicinity of standard-design nuclear power plants--II. Wind-tunnel evaluation of building-wake characteristics.

Laboratory experiments were conducted to simulate radiopollutant effluents released to the atmosphere from two standard-design nuclear power plants. The main objective of the study was to compare the dispersion in the wakes of the plants with that in a simulated atmospheric boundary layer. Dispersion functions are determined that describe the spread of the effluent plume in the wake of each plant. These dispersion functions are described by power laws. They are determined for three incident wind angles and the number of stacks associated with each plant. Lateral plume spread was directly related to the silhouette area of the plants. A graphical technique is presented relating the lateral dispersion to the associated silhouette area of the building or building complex.

Air Pollution, Radioactive↗
PubMed1982

Vascular injuries near the knee: an updated series and overview of the problem.

Injury of the popliteal artery results in amputation more often than any other arterial injury. Adjacent injuries, small vessel thrombosis, and muscle necrosis are the major deterrents to limb salvage. This report updates a previously published series, expanded to include 110 injuries treated during a 14-year period. Emphasis is placed on the management of adjacent injuries, errors promoting amputation, and principles of improving limb survival. The hallmark of success is the rapid and complete restoration of arterial and venous flow.

Adolescent↗
PubMed1981

Cimetidine vs antacid in prophylaxis for stress ulceration.

Seven-seven critically ill patients were prospectively randomized into four groups to compare antacids and various doses of cimetidine in the neutralization of gastric acid for preventing complications of stress ulcers. Gastric pH was monitored hourly, basing the efficacy of neutralization on preselected pH values for each study group. Cimetidine provided adequate neutralization in 14 (23%) of 61 patients. Gastric acid in all 16 patients treated with antacids was adequately neutralized. Stress bleeding occurred in three (5%) patients treated with cimetidine and in no patient treated with antacids. Reversible thrombocytopenia developed in six (26%) of 23 patients treated with 2,400 mg/day of cimetidine. Hourly monitoring of gastric pH is a mandatory component in the prevention of stress bleeding. Antacid is the preferred agent for gastric acid neutralization because it is more effective, safer, and less expensive.

Adolescent↗
PubMed1981

Early identification of patients prone to develop adult respiratory distress syndrome.

Fifty-nine intubated nonhypoxic patients with clinical criteria associated with adult respiratory distress syndrome were studied. Clinical measurement were sought to identify patients before severe hypoxemia occurred. Etiologic factors, chest roentgenography, effective static compliance, intrapulmonary shunt and arterial blood gases on 40 and 100 percent inspired oxygen were analyzed. Pulmonary failure occurred in 22 patients, while 37 had minimal pulmonary difficulties. Comparison of these two groups revealed that only sequential arterial oxygen tensions accurately predicted pulmonary deterioration. A 40 percent arterial oxygen pressure below 100 torr and a 100 percent oxygen pressure below 350 torr indicated a 95 percent probability of pulmonary deterioration. When either determination was above these levels, the probability of pulmonary deterioration was 10 percent. The use of sequential arterial blood gases allows the selection of high risk patients for adult respiratory distress syndrome. This ensures that therapy is offered at the most beneficial time.

Bacterial Infections↗
PubMed1980

The surgical management of duodenal trauma. Precepts based on a review of 247 cases.

The lethal potential of duodenal trauma relates to the severity of the defect, associated injuries, and the adequacy and expedience of treatment. We studied 247 patients whose injuries were managed at a single institution during an 18-year period. Emphasis was placed on complications directly related to the duodenal wound and the selection of operative repair. Repairs consisted of duodenorrhaphy in 190 patients (83%) and more complex procedures in 33 (13%). Death resulted from the duodenal injury in nine patients (4%) and fistula developed in 16 (7%). Factors associated with an increase in the morbid potential of the duodenal wound were (1) missile or blunt injury, or a defect larger than 75% of the circumference; (2) injury of the first or second portion; (3) an injury-operation delay of more than 24 hours; and (4) adjacent common bile duct injury. These factors require consideration in the selection of the operative repair.

Adolescent↗
PubMed1980

Complications and results of 160 Baker tube plications.

The basic indication for Baker tube plication is widespread enteric serosal injury. The prediction of subsequent small bowel obstruction remains difficult. Consequently, the benefits of Baker tube plication cannot be clearly defined. A therapeutic decision must be made by weighing the known facts. In this series of 160 Baker tube plications, the incidence of tube complications was 7 percent. Witzel tunnel construction of the jejunostomy was judged important in reducing the complications of this procedure. The incidence of recurrent obstruction was 9 percent with an average follow-up period of 3.9 years.

Adolescent↗
PubMed1980

Carotid artery injuries caused by blunt trauma.

Carotid artery injuries caused by blunt trauma often cause thrombosis and delayed neurologic deficits, and are associated with mortality rates of up to 40%. In this series of 17 patients with blunt trauma of the carotid, three had no symptoms, ten patients had limb paresis and four had severe neuroligic deficits. The wounds were identified by arteriography; repair was attempted in 15 patients, and successful in eight. All eight patients with successful repair were improved or normal after surgery, but only two out of nine patients without repair improved, and four died. The mortality rate for the series was 23%, but only 14% in the patients who had carotid surgery. This experience suggests that repair is safe and effective in patients with carotid injuries in whom prograde flow continues and only mild neurologic deficits are present. In contrast, patients with complete occlusion, severe neurologic problems, and altered consciousness are not likely to be helped by attempts at revascularization.

Adolescent↗
PubMed1979

Early positive end-expiratory pressure in the adult respiratory distress syndrome.

This prospective study was designed to determine the effect of positive end-expiratory pressure (PEEP) instituted early in the course of adult respiratory distress syndrome (ARDS). Seventy-nine (7%) of 1,200 patients admitted to the surgical intensive care unit were selected because of a high probability that ARDS would develop, and were randomized into two treatment groups. Of the 79 patients, 45 were immediately treated with 5 cm H2O of end-expiratory pressure (early PEEP group), and 34 received PEEP only when severe hypoxemia developed (late PEEP group). The incidence of ARDS was significantly lower in the early PEEP group than in the late PEEP group (20% vs 53%; P less than .002). Fewer pulmonary deaths occurred in this group (11% vs 29%; P = .02), and there was less pulmonary morbidity. This study supports the efficacy of early low-level PEEP in the treatment of patients for whom there is a high probability that ARDS will develop.

Clinical Trials as Topic↗
PubMed1979

Late false aneurysm of the carotid artery: repair with extra-intracranial arterial bypass.

A patient with a rapidly enlarging symptomatic false aneurysm of the internal carotid artery 30 years after nonoperative treatment of a penetrating neck injury is presented. Preoperative compression of the aneurysm precipitated transient cerebral ischemic attacks. Complete interruption of the right internal carotid artery inflow during aneurysmectomy was considered to be fraught with great danger. An extra-intracranial arterial bypass was therefore performed, and then aneurysmorrhaphy was easily performed and saphenous vein graft interposition accomplished. The importance of early definitive treatment of arterial injuries is emphasized. The bypass used allowed additional cerebral blood flow when complete occlusion of the carotid artery was contraindicated.

Aneurysm↗
PubMed1979

Civilian popliteal artery trauma: an eleven year experience with 83 injuries.

Limb loss is the outcome in one third of previously reported popliteal artery injuries. This report summarizes 83 injuries with an amputation rate of 9.6%. Penetrating traumas accounted for 61 (73%) injuries and blunt traumas for 22 (27%). The incidence of amputation varied with injury type from none in seven stab wounds to three of 19 (15.8%) shotgun wounds. Distal ischemia or a pulse deficit highlights the presence of arterial trauma, and the external wound defines its site in most patients. Urgent operation is indicated by these findings. Equivocal findings suggest less compromised flow, and such patients are managed best by arteriographic confirmation before operation. Early systemic anticoagulation is indicated to decrease distal small-vessel thrombosis. The successful management of these injuries requires early and complete restoration of arterial and venous flow. This is accomplished most effectively by priority definitive reconstruction. Compulsive attention to complete restoration of arterial flow during the initial procedure is mandatory. Resection or bypass of all damaged arterial wall, liberal use of autogenous vein grafts, and repair of concomitant venous injuries enhance continued arterial patency. Routine distal catheter thrombectomy and frequent intraoperative arteriography promote and confirm complete reconstruction. Early performance of four quadrant fasciotomy is indicated if compartmental hypertension is suspected. Thorough debridement of injured and questionably viable soft tissue and adequate fracture stabilization are integral parts of successful revascularization.

Adolescent↗
PubMed1978

The validity of normal arteriography in penetrating trauma.

The detection of underlying arterial injury is a major problem in the management of penetrating trauma. Arteriovenous fistula and false aneurysm are late sequelae of unrepaired injuries. The diagnostic accuracy of arteriography in clinically occult injury has not been defined. One hundred and seventy-seven patients with 183 penetrating extremity wounds underwent arteriography followed by operative vessel exploration. Arteriogram/operation correlation demonstrated 36 true-positive, 132 true-negative, 14 false-positive, and one false-negative arteriogram. Arteriography is sufficiency sensitive to exclude the presence of arterial injury in patients with equivocal clinical signs of injury. The radiographic changes are often sublte and diagnostic accuracy demands attention to the details of technique and interpretation. Unequivocal clinical signs of arterial injury and any arteriographic abnormality are indications for operative exploration.

Angiography↗
PubMed1977

Diagnosis of hyperparathyroidism.

States of hypersecretion of PTH may occur primarily, or in response to other physiologic abnormalities. Primary hyperparathyroidism must be considered in the differential diagnosis of hypercalcemia, nephrolithiasis, metabolic bone disease, and pancreatitis and peptic-ulcer disease. The clinical manifestations of this disease have become more subtle with improved detection. The serum calcium level is almost always elevated, and when it it accompanied by relatively high serum PTH levels or increased urinary cAMP excretion, the diagnosis is usually secure. Findings of hypophosphatemia, decreased renal tubular reabsorption of phosphorus, hypercalciuria, and characteristic roentgenographic changes support the diagnosis of hyperparathyroidism, but are not prerequisites for that diagnosis. Most cases will come to operation, and experienced intraoperative assessment is necessary for the correct distinction between multiglandular disease and that involving only a single gland. We expect that a clearer understanding of the histopathologic features of these diseases, and improvement in the methods for measurement of PTH will be the main areas of advancement in the diagnosis of hyperparathyroidism in the next few years.

Bone Diseases↗
PubMed1976

Metabolic effects of parathyroidectomy in asymptomatic primary hyperparathyroidism.

Effects of parathyroidectomy on parathyroid function and calcium (Ca) metabolism were carefully evaluated in 6 patients with primary hyperparathyroidism without symptoms normally attributed to the disease and in 7 with bone disease or nephrolithiasis. Before parathyroidectomy, both groups of patients demonstrated evidence of the sequelae of parathyroid hormone (PTH) excess, since they presented one or more of the following features: low bone density by 125I-photon absorption, hypercalciuria (urinary Ca greater than 200 mg/day on an intake of 400 mg/day), negative Ca balance (absorbed Ca less than urinary Ca), elevated fasting urinary Ca greater than 0.2 mg/mg creatinine for a night-time sample after a 6-hour fast), and decreased renal function (creatinine clearance of less than 65 ml/min). Following parathyroidectomy, most of these deleterious effects were reversed commensurate with the return of immunoreactive serum PTH, serum Ca, and urinary cyclic AMP toward normal. These quantitative non-invasive techniques may be useful for the initial evaluation and follow-up of patients with asymptomatic primary hyperparathyroidism.

Adult↗
PubMed1976

Venography in penetrating injuries of the extremities.

Of 30 consecutive cases of penetrating injuries to the extremities studied both by arteriography and venography, five were found to have significant venous injuries. Three of these cases are presented to show the value of venography in detecting inadequate venous collateral circulation, intraluminal thrombus, and venous obstruction. It is suggested that preoperative venography will compliment arteriography, aid in the diagnosis of venous injuries, demonstrate variable venous anatomy, and outline other venous pathology outside of the area of trauma.

Adult↗