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Biomedical subjects

P N Manson

Publications and source records attributed to P N Manson.

At least 19 recordsLinked to original sources
PubMed1992

The use of hyperbaric oxygen for preservation of free flaps.

The effects of hyperbaric oxygen (HBO) during tissue preservation on flap survival have been investigated in free flaps in rats. Groin skin flaps were harvested, stored in either room air or HBO (100% oxygen at 2.9 atm absolute) at 23 degrees C for 18 hours, and transplanted to the contralateral groin. Free flaps exhibit a high incidence of complete necrosis in the room air control. The survival of free flaps stored under HBO increased from 10% to 60% (p less than 0.05) after 18 hours of preservation. Skin flaps exhibited an increase in tissue hypoxanthine by 3.6-fold normal after 18 hours of storage in room air. HBO preservation prevented the accumulation of hypoxanthine and inhibited xanthine oxidase. Inhibition of the xanthine oxidase system may be one of the mechanisms of improved success of skin flap transplantation.

Animals↗
PubMed1992

Local muscle flap in a venous hypertensive environment.

Local rotation muscle flaps are useful for soft tissue reconstruction in open grade III fractures of the lower extremity. Gastrocnemius or soleus muscle flaps provide early bone coverage and avoid a more demanding free tissue transfer. Deep vein thrombosis is common in injured limbs and venous hypertension may result in acute muscle flap necrosis. Loss of bone coverage and an increased risk of osteomyelitis follow. We present a successful soleus rotation flap for tibial coverage in a lower extremity with a documented major venous thrombosis.

Adult↗
PubMed1992

Thyroid disorders masquerading as aging changes.

Some (2.6%) patients seeking aesthetic blepharoplasty had undiagnosed hypothyroidism contributing to periorbital aging changes; 0.3% had undiagnosed hyperthyroidism. Characteristic features suggesting the possibility of hypothyroidism were edema, "festoons," and "secondary" bags. The characteristic features of hyperthyroidism were proptosis and edema. Treatment of the underlying medical condition reversed the changes to a variable extent. Aesthetic surgery was not necessary in some patients.

Adult↗
PubMed1992

Panniculus morbidus.

Eight patients with large panniculi are described where severe problems with hygiene, immobility, and chronic infection were caused by the lymphedematous, chronically infected pannus. Protracted nonsurgical management of the infected panniculus had failed in all 8 patients. Wedge resection without fat undermining removed diseased tissue. Infection and sepsis were eliminated and ambulation was restored in all patients. Formerly immobile patients were returned to normal activity. Significant self-induced weight loss was not observed in a 2-year follow-up period; weight gain, however, was not experienced. The primary anesthetic method was thoracic epidural reducing the requirements for general endotracheal anesthesia. The chronically infected pannus is a surgical problem deserving earlier recognition and resection.

Abdomen↗
PubMed1992

The fate of plates and screws after facial fracture reconstruction.

Rigid plate and screw fixation is the mainstay of treatment for complex fractures of the facial skeleton. Complications of plate and screw fixation include prominence, infection, exposure, and migration. Five hundred and seven patients undergoing plate and screw fixation for facial fractures (1112 fractures) from 1983 to 1988 were followed for complications. Sixty-one patients (12 percent) required hardware removal. The location on the facial skeleton influenced symptoms and the rate of hardware removal. Infection and exposure may be decreased with antiseptic irrigations, avoiding mucosal damage, attention to proper mucosal closure, and correct placement of plates. Prominence may be decreased by the use of microplates in the supraorbital, frontal, and naso-orbital-ethmoid locations.

Adolescent↗
PubMed1992

Nasoethmoid orbital fractures. Current concepts and management principles.

The proper management of nasoethmoid orbital fractures relies upon early accurate diagnosis and treatment. A surgical plan must be established after careful review of the physical examination and CT scans. Identification of the extent and type of fracture pattern determines the operative approach. Extended (wide) exposure, using craniofacial techniques, facilitates precise reduction and rigid fixation of all bone fragments. Transnasal reduction of the canthus-bearing central segment (medial orbital rim) is the critical operative maneuver required to achieve normal intercanthal distance. Immediate bone grafting replaces severely comminuted or missing bone fragments. The skin overlying the nasoethmoid area is carefully redraped by gentle pressure from padded external compression bolsters. These principles form the basis for superior aesthetic and functional results.

Bone Transplantation↗
PubMed1992

Microvascular soft-tissue transplantation for reconstruction of acute open tibial fractures: timing of coverage and long-term functional results.

Seventy-two patients with Gustilo grade IIIB open tibial fractures were treated with free-tissue transfers. If successful free-tissue transfer for soft-tissue reconstruction is performed within 15 days of injury, the risk of major complications is 3.6 percent. Long-term retrospective follow-up (mean 42 months) revealed successful limb salvage in 93 percent, good aesthetic results in 80 percent, and patient satisfaction in 96 percent. However, 66 percent of patients exhibited significantly decreased range of motion of the ankle, 44 percent experienced swelling and edema requiring elastic support and activity modification, and 50 percent occasionally required an assistance device for ambulation. The long-term employment rate was 28 percent, and no patient returned to work after 2 years of unemployment. In contrast, 68 percent of amputees after lower extremity trauma over the same period returned to work within 2 years. Patients need to realize the disruptive nature of this injury on their family, job, and future.

Acute Disease↗
PubMed1991

Pathophysiology of sea nettle (Chrysaora quinquecirrha), envenomation in a rat model and the effects of hyperbaric oxygen and verapamil treatment.

The effect of lethal sea nettle envenomation on the morphology and blood flow in various rat organs was characterized and the influence of two antidotes (hyperbaric oxygen and verapamil) was compared. Either antidote slightly prolonged survival, but the protective effects were not statistically significant. The venom caused no histologic alterations in brain, heart, or lungs but induced hepatic and renal necrosis. Hepatocytes in mid-zonal regions and renal tubular epithelium were the cell types predominantly affected. Hyperbaric oxygen and verapamil did not decrease the hepatic injury. The venom did not influence central hemodynamics until preterminally and it diminished blood flow to brain, but not to liver or kidney. Hyperbaric oxygenation protected against venom-induced decreases in blood flow to the brain. These results add toxic hepatic and renal necrosis and cerebral ischemia to the pathophysiology of envenomation in this model.

Animals↗
PubMed1991

Evidence for an early free radical-mediated reperfusion injury in frostbite.

Frostbite is characterized by acute tissue injury induced by freezing and thawing. Initial complete ischemia is followed by reperfusion and later, tissue necrosis. These vascular events support the hypothesis that free radical-mediated reperfusion injury at thawing might contribute to tissue necrosis after frostbite in a manner similar to that seen after normothermic ischemia. To test this hypothesis, rabbit ears were frozen at -21 degrees C for 30, 60, 90, or 120 s and rewarmed at room temperature (22 degrees C). Rabbits were treated "blindly" with saline alone, highly purified, pharmaceutical grade superoxide dismutase (SOD), allopurinol, or deferoxamine. The area of ear necrosis was determined 3 weeks after frostbite by "blinded" morphometry. The administration of SOD at the time of thawing significantly improved viability in ears frozen for 60 and 90 s, but not in those frozen for 30 or 120 s. Deferoxamine also improved viability in ears frozen for 60 s. Allopurinol did not significantly affect ear survival. Electron micrographs showed the appearance of severe endothelial cell injury beginning during freezing and extending through early reperfusion. Later, neutrophil adhesion, erythrocyte aggregation, and microvascular stasis were seen. These findings suggest that free radical-mediated reperfusion injury has a role in frostbite, and quantitate the proportion of the injury that is due to this mechanism.

Allopurinol↗
PubMed1991

The healing of facial bone fractures by the process of secondary union.

The mechanism of healing of facial bone fractures was investigated in a rabbit model. Twelve New Zealand white rabbits underwent surgically induced fractures of the right infraorbital rim and fracture ostectomies (4 to 5 mm) of the left infraorbital rim. Animals were sacrificed 2, 4, and 8 weeks postfracture. Bone, including periosteum, obtained from each fracture or fracture osteoctomy site was divided longitudinally for hematoxylin and eosin staining, fluorescent microscopy, microangiography, and microradiography. Sequential fluorochrome labels of oxytetracycline (30 mg/kg), alizarin complexone (30 mg/kg), DCAF (20 mg/kg), and xylenol orange (90 mg/kg) were administered 24 hours preoperatively and at 1, 2, 4, and 8 weeks postfracture. All fracture and fracture ostectomy sites demonstrated vascular ingrowth, mineralization, and woven bone formation by 2 to 4 weeks postoperatively, beginning with a cartilage precursor. Subsequently, the woven bone was replaced with remodeled lamellar bone, resulting in complete bony healing by 8 weeks postoperatively. These steps were substantiated by microscopic, microradiographic, and radiologic examination of the specimens. This study demonstrates that fractures of the facial bones in a rabbit model heal by a process of new bone formation that resembles secondary union in endochondral bones.

Animals↗
PubMed1991

Management of the medial canthal tendon in nasoethmoid orbital fractures: the importance of the central fragment in classification and treatment.

The medial canthal tendon and the fragment of bone on which it inserts ("central" fragment) are the critical factors in the diagnosis and treatment of nasoethmoid orbital fractures. The status of the tendon, the tendon-bearing bone segment, and the fracture pattern define a clinically useful classification system. Three patterns of fracture are appreciated: type I--single-segment central fragment; type II--comminuted central fragment with fractures remaining external to the medial canthal tendon insertion; and type III--comminuted central fragment with fractures extending into bone bearing the canthal insertion. Injuries are further classified as unilateral and bilateral and by their extension into other anatomic areas. The fracture pattern determines exposure and fixation. Inferior approaches alone are advised for unilateral single-segment injuries that are nondisplaced superiorly. Superior and inferior approaches are required for displaced unilateral single-segment injuries, for bilateral single-segment injuries, and for all comminuted fractures. Complete interfragment wiring of all segments is stabilized by junctional rigid fixation. All comminuted fractures require transnasal wiring of the bones of the medial orbital rim (medial canthal tendon-bearing or "central" bone fragment). If the fracture does not extend through the canthal insertion, the canthus should not be detached to accomplish the reduction.

Ethmoid Bone↗
PubMed1991

The effect of rigid fixation on growth of the neurocranium.

The effects on skull growth of plating the coronal suture and frontal bone were studied in New Zealand White rabbits. Three-dimensional coordinate landmarks were digitized and analyzed to determine the differences in form between operated and unoperated animals using Euclidian distance matrix analysis. This method compares sets of interlandmark distances in three dimensions and was used to demonstrate changes induced by plating. We interpret these changes in morphology to be the result of differences in growth between the operated and unoperated groups. Periosteal elevation alone (n = 6) resulted in a minimal local growth increase. Coronal suture plating (n = 8) resulted in local growth restriction with contralateral and adjacent size increases. Frontal bone plating (n = 6) without crossing a suture line also resulted in local growth restriction and adjacent bone size increases. The timing of intervention in relation to the completion of bone growth may explain the magnitude of clinically apparent effects. Changes in bones adjacent to those directly manipulated may be an attempt to maintain a normal skull volume.

Animals↗
PubMed1991

High-energy orbital dislocations: the possibility of traumatic hypertelorbitism.

In a 4-year period from 1983 to 1987, 7160 patients with blunt injuries were admitted to the Maryland Institute of Emergency Medical Services Systems Shock Trauma Center. Facial injuries occurred in 10 percent of this population. High-energy fractures (characterized by computed tomography) were seen in approximately 10 percent of these patients. In this high-energy group, five cases of high-energy orbital dislocations, some representing examples of traumatic hypertelorbitism, were observed. They represent 1.5 percent of the 342 midface fractures observed and 4.8 percent of the naso-orbital ethmoid fractures observed (105 patients). One additional patient is described who was seen at the UCLA Medical Center for late repair of the condition. High-energy impacts of the upper midface created fractures of both orbits, zygomas, and nasoethmoidal regions permitting lateral transposition, enlargement, and divergence of the orbits. Interorbital, intercanthal, and interpupillary distances were increased, criteria that confirm the diagnosis of hypertelorbitism. Fifty percent of the patients were bilaterally blind, and one patient sustained unilateral blindness.

Adult↗
PubMed1990

The effects of hyperbaric oxygen on free flaps in rats.

The effects of hyperbaric oxygen on survival were investigated in free flaps and island flaps. Skin flaps transplanted following 18, 21, and 24 hours of preservation at 24 degrees C demonstrated survival rates of 20%, 10%, and 0%, respectively. Treatment with hyperbaric 100% oxygen improved the survival rates to 66%, 67%, and 40%. A preservation time of 21 to 24 hours at room temperature appears to be the threshold of irreversible ischemic damage. In acute island flaps, flap survival was improved significantly from 35% to 53% and 64% of the random flap area by preoperative or postoperative treatment, respectively. Prolonged preoperative and postoperative treatment improved survival to 66%.

Animals↗
PubMed1990

Techniques for improved visibility and lid protection in orbital explorations.

Visualization during exploration of the orbit is hampered by herniation of orbital fat around the malleable retractor in posterior orbital dissection. A thin stiff disc of plastic sheeting, placed between the dissected orbital soft tissue contents and the malleable retractor, reduces prolapse of fat around the edges of the orbital retractor. The technique is utilized in acute fracture treatment and in late orbital reconstruction. The malleable retractor, placed below the plastic disc, may be easily taken in and out of the orbit with reduced damage of fat and enhanced visualization. Retractor damage to fat is reduced and visualization enhanced. The plastic sheet may be inserted over an intact posterior bony "ledge" in floor fractures, allowing accurate placement of bone grafts under direct visualization. Additionally, the use of a segment of flexible rubber sheeting sewed over a subciliary incision margin reduces traction injury, drill and cautery damage to eyelid skin.

Eyelids↗
PubMed1990

Sequencing LeFort fracture treatment (Organization of treatment for a panfacial fracture).

The types of midfacial fractures and their complexity were evaluated in admissions to the Maryland Institute of Emergency Medical Service Systems (MIEMSS) during the years of 1984 to 1988. Two hundred and sixty-eight LeFort fractures were treated and followed (3.2 percent of admissions). One half (50 percent) had skull fractures and 40 patients (15 percent) had LeFort, skull and mandibular fractures. Isolated nasoethmoidal fractures were observed in 176 patients and in 107 patients (39 percent) of patients with LeFort fractures. Isolated mandibular fractures were observed in 321 patients and in 104 patients with LeFort fractures (39 percent). Eleven percent of patients had midfacial, nasoethmoidal and frontal sinus fractures. Six percent of patients had midfacial, frontal bone, frontal sinus and nasoethmoidal fractures (Cranial Base Crush Syndrome). Twenty two percent of patients had LeFort and frontal sinus fractures. Reconstruction of multiple area injuries is simplified by a highly organized treatment sequence that conceptualizes the face in two groups of two units. Each unit is divided into sections, and each section is assembled in three dimensions. Sections are integrated into units and units into a single reconstruction. Conceptually, in each unit, facial width must first be controlled by orientation from cranial base landmarks. Projection is then (and often reciprocally with width) established. Finally, facial length is set both in individual units and in the upper and lower face. Soft tissue is considered the "fourth dimension" of facial reconstruction. Bone reconstruction should be completed as early as possible to minimize soft tissue shrinkage, stiffness and scarring of soft tissues in nonantomic positions.(ABSTRACT TRUNCATED AT 250 WORDS)

Fracture Fixation↗
PubMed1990

Le Fort fractures without mobility.

The Le Fort fracture without maxillary mobility constitutes 9 percent of maxillary fractures observed over a 3-year period. A high Le Fort (level II or III) injury exists as a one- or two-piece incomplete fracture. The degree of fracture is insufficient to permit mobility of the maxillary alveolus. Frequently, an obvious unilateral zygomatic fracture is present. Physical findings consist of bilateral eyelid ecchymosis and malocclusion. The occlusal disturbance may consist of either crossbite, open bite, maxillary rotation, or lack of proper dental intercuspation. On CT scan, fractures are best demonstrated in the posterior and medial maxillary walls at the Le Fort I level; they are most obvious unilaterally with contralateral fractures that may be subtle. Bilateral maxillary sinus fluid is consistently present on CT. Treatment usually consists of observation and traction elastics but may require mobilization of the fragments followed by open reduction and rigid fixation.

Humans↗