Biomedical subjects
Publications and source records attributed to T M Davidson.
Hemoglobin enhances the virulence of E. coli in the peritoneum. This study investigates the effect of blood on the virulence of E. coli and human oral anaerobes in the mouse neck. E. coli neck infectivity is significantly enhanced by blood. Oral anaerobic infections are not affected.
There is renewed interest, particularly by head and neck surgeons in the pathophysiology of swallowing. Some of the reasons for this are an increased number of patients in the following categories who have swallowing problems: 1) patients postoperative from procedures in the head and neck, e.g., partial laryngectomy, partial or complete excisions of the tongue, pharynx, or mandible; 2) patients with peptic ulcer, hiatal hernia, esophageal diverticula, and cardiospasm; 3) patients who survive severe central nervous system problems such as stroke, brain tumors, aneurysms, or degenerative disease; and 4) patients who survive serious accidents with severe neck trauma. This paper reviews the pathophysiology of swallowing and the methods of diagnosing and treating dysphagia and its complications.
Basal-cell and squamous-cell carcinomas frequently develop on or around the oral lips. They are treatable by surgery. The principles of surgical excisions from and reconstructions of the site are outlined and illustrated for small, medium, and large lesions.
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Lateral canthopexy using permanent suspending sutures to shorten the lateral canthal tendon helps prevent scleral show, increased sloping of the upper lid, and inferomedial displacement of the lateral canthus following lower lid blepharoplasty. While these complications usually are prevented by flap suspension techniques, in which more skin is excised above and lateral to the commissure than below it, sutures running from the inferomedial part of the lateral canthal tendon to its superolateral aspect and to periosteum just inside the orbit still further reduce the tendency toward the complications mentioned. We report technical aspects and results. After several years of clinical experience, we have the impression that the technique is a useful adjunct, even though it may produce more swelling and inflammation and a longer recuperative period.
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The management of snake bites once the patient reaches the hospital should be to obtain the necessary blood parameters (type and cross-matched blood, complete blood count, platelets, PT, PTT, fibrinogen and fibrin split products, electrolytes and calcium), to evaluate the fang marks and the neurovascular status of the involved extremity and to monitor systemic signs and symptoms. These steps are extensively described in the literature, and are commonly agreed upon. We then start intravenous antivenom, after appropriate skin testing for horse serum allergy, beginning with 4--5 vials (8--10 in children) over the initial 30--60 minutes and titrating to cessation of the progression of the toxic signs. Concomitantly, we measure intracompartmental and subcutaneous tissue pressure in all clinically suspected areas. If intracompartment pressures are less than 30 mm Hg, surgical intervention is not necessary; antivenom is continued as necessary and the wick catheter measurements are repeated if indicated. If pressures are greater than 30 mm Hg,immediate surgical decompression is advisable.
Nasal profiles are altered in almost every rhinoplasty operation. Often neglected in diagnosis and surgery are alterations in profiles of the cheeks and upper lip that should be made at the same time. We show aesthetic effects produced by alterations in these structures and describe how we measure and record the adjustment. A few examples of results are presented to indicate the techniques used and the importance of including changes in profiles of the cheeks and upper lip in cosmetic rhinoplastic diagnosis and treatment.
The rhomboid and other 60 degrees transposition flaps have theoretical and practical disadvantages for many applications. A better flap for these is one having an angulation of 30 degrees at its distal end. When this 30 degrees flap is combined with the M-plasty, a versatile and cosmetically favorable repair is provided for many surface defects. In fact, over the years, it has become our most useful method of closure with flaps. Fundamentally, it allows sharing of tensions of closure better than does the rhomboid flap, produces less level disparities or protrusions than does any 60 degrees flap, and its resulting scar length is only fractionally longer than that of the rhomboid flap. Rhomboid and other 60 degrees angle flaps have been exceedingly valuable tools to many surgeons; the 30 degrees flap combined with M-plasty should be significantly more useful.
Blepharoplasty on lower lids frequently results in a downward pull on the free border of the lid and inferomedially on the lateral canthus. Extending the incision in the lower lid upward and lateral to the outer canthus allows most of the excision to occur laterally. Closure then pulls superolaterally, which tends to prevent the commonest complications of blepharoplasty on lower lids.
Lateral osteotomies performed posteriorly enough to avoid step-like prominences at the sides of the nose may allow medial displacement of bone to impinge on the airways. This obstruction near the floor of the nasal passageway is prevented by leaving a triangular piece of bone at the pyriform aperture intact just superior to the level of the inferior turbinate. A curved lateral osteotomy, as described here, cuts bone posteriorly only where aesthetic narrowing is required in rhinoplasty. Techniques providing the recommended curved or angulated lateral osteotomies with osteotomes are demonstrated in the cadaver and in patients.
Photographs, drawings, and examination at consultation have value in rhiniplastic planning. However, the surgeon is not operating on photographs, drawings, or an alert sitting or standing patient; he is operating on a nose with what was forward now facing upward. We find it most helpful to plan and mark almost the entire procedure on the external nose and surrounding structures just before the patient is put supine and sedated or anesthetized. In primary rhinoplasty, it is possible to mark essentially all skeletal anatomy within 1 mm tolerances by palpation, pushing the tip up and back, observing the changes from the outside, and looking at the inside. We believe that the anatomy and planned changes can and should be depicted by appropriate marks put on the skin. There mere act of drawing in the procedure forces us to think it through from beginning to end, a most worthwhile endeavor. Moreover, we learned very shortly after we began forcing ourselves to quantitate the anatomy and proposed changes, that we ran into fewer and fewer surprises as we worked. Photographs taken of the markings become by far the best "operative note" we can have. Comparison of these with the patient or his photographs showing the result allow us to make accurate judgments about long term effects of each surgical maneuver. Much that seemed mysterious before is found to be quite scientifically explainable. We do not propose in this short report to show how we mark every nose. Rather we shall show with drawings and a few examples how we go about marking a nose. The reader may use the suggested marking techniques or may evolve his own. The important thing is that he work out a system meaningful to him. It will be noted that we have used differing techniques for depicting similar concepts from case to case. In other words, we have not settled immutably on one system because we are still searching for the best.
The possibility of improving the cure rate of cancer of the head and neck by radical neck dissection of the clinically negative neck (elective neck dissection) continues to pose a therapeutic dilemma. This paper seeks to review the available information, analyze relevant aspects of the issue and attempt to draw conclusions which will be helpful both to physicians and their patients. The discussion is confined to squamous carcinoma of the larynx, pharynx, and oral cavity.
Cosmetic and functional restoration of the fractured mandible in the great majority of cases is the sine qua non of therapeutic success. Not only must an acceptable low complication rate be obtained, but when present, their complex nature must be understood from the onset. Successful treatment of complications is a multifaceted problem requiring planned, interdisciplinary, often times staged reconstruction. The radiologist and dental prosthodontist make valuable contributions towards the surgeon's ultimate rehabilitation of the patient. A three year experience of 111 mandibular fractures treated on the UCSD Otolaryngology Service is characterized. Sixteen complications nine of which were seen after initial treatment elsewhere provide the focus of this report. Special emphasis is given to the pre-treatment planning and surgical techniques necessary to correct malunion and nonunion. Particular advantages achieved by the use of osteogenic autogenous marrow, cellulose acetate filters and Vitallium (chrome cobalt) trays are detailed.
Because of difficulties in making accurate measurements from before and after photographs, we have devised measuring techniques not dependent upon exact reduplication of photographic circumstances before, during, and after surgery. Measuring devices contacting the head of the patient in specified ways are described. They allow simple and exact reduplication so that measurements made at different times can be compared. Lengths of nose and of columella and actual projection of brow, nasofrontal angle, rhinion, supratip region, the tip itself, and of the columella-labial junction can be measured. Tip rotation, cephalic or caudal, can be determined and quantitated. The devices and techniques for using them are described. We believe that employment of the suggested measuring techniques will allow better reporting of rhinoplastic methods and results should significantly increase our understanding of this complex surgical procedure.