Biomedical subjects
Publications and source records attributed to C G Mellow.
A radial-artery free flap was dissected from a traumatically amputated forearm. During dissection the arterial tree was found to be abnormal, with no radial artery. The arterial supply was based on co-dominant median and ulnar arteries. This description raises issues regarding anatomical vascular aberrations when planning forearm flaps.
There has been great interest stimulated by reports on factors influencing the survival of skin flaps which possess only venous inflow and outflow, i.e., venous flaps. The present study serially (Days 1, 2, and 4 postoperatively) observed several biochemical factors which might affect flap survival. ATP levels were measured to assess endogenous energy stores, malonyldialdehyde (MDA) and xanthine oxidase (XO) to estimate free radical production, superoxide dismutase (SOD) to quantify antioxidant defenses, and edema to measure inflammatory changes. Eighteen thighs on nine dogs were assigned randomly to one of three groups: full-thickness skin grafts, flaps based solely on the saphenous artery and vein (AV flaps), or flaps based solely on the saphenous vein (venous flaps). These were regarded as being mostly ischemic, totally perfused, and partially ischemic, respectively. Control skin biopsies were obtained adjacent to surgical sites. AV flaps and control skin were similar in all respects. Venous flaps compared with skin grafts were significantly less edematous (P less than 0.01) had less MDA and XO (P less than 0.05), but no significant differences in SOD and ATP levels. However venous flaps had significantly less ATP than AV flaps (P less than 0.01). Thus venous flaps survive despite depletion of ATP levels. These results suggest that decreased free radical production and lessened edema may be important factors in promoting ultimate survival of venous flaps.
In this study rat epigastric island flaps were used as a model to investigate selected tissue biochemical changes occurring during secondary ischemia. It was hypothesized that free radical damage, depletion of free radical scavengers, depletion of ATP, and increased edema might explain differences in flap survival between partial (venous obstruction) and total (arteriovenous obstruction) ischemia and decreased flap survival with increasing ischemia time. Flaps were given 2 hr or primary ischemia, 8 hr of normal perfusion, then secondary ischemia of 0, 2, 4, 8, or 12 hr with either arteriovenous obstruction or venous obstruction. Biochemical analysis of the skin was performed after 0, 24, or 96 hr reperfusion. Only minor differences were found between arteriovenous and venous ischemia for any of five biochemical parameters, despite a previous finding that venous ischemic flaps are more susceptible to necrosis. Levels of xanthine oxidase and malonyldialdehyde (both indices of free radical generation) increased with ischemia time. Levels of superoxide dismutase (a free radical scavenger) correspondingly decreased. Tissue levels of ATP decreased after ischemia and recovered to normal for shorter but not for longer ischemia times after 96 hr of reperfusion in parallel with flap survival. Edema increased immediately after the ischemic insult but decreased once the tissue became necrotic. These results imply roles for free radicals, ATP, and edema in secondary ischemia, but do not distinguish between arteriovenous and venous secondary ischemia.
Arterial spasm due to exaggerated sympathetic response is an important mechanism for Raynaud's phenomenon in scleroderma associated often with periadventitial scarring. The results of cervical sympathectomy have been unsatisfactory in the upper limb because of additional sympathetic pathways. Flatt therefore devised a distal sympathectomy by stripping the vessels of their adventitia over a short length of artery. The results of this operation were found by Wilgis in a large series to be poor in patients with scleroderma. A radical distal microarteriolysis including adventitia and surrounding scar is described and the results in 13 patients, 11 with scleroderma, are reported. Minimum follow-up is one year. All patients had relief from pain at rest and healing of painful ulceration. Mild recurrence of small ulcers was seen in only four patients.
In a previous study, timing relationships were studied for flaps subjected to secondary ischemia by total pedicle interruption. In the current paper, using a rodent epigastric flap, a similar study for flaps subjected to secondary ischemia by venous obstruction was performed. These conditions were designed to mimic a venous thrombosis following flap transfer, as would be performed clinically. In Experiment 1, the time interval between primary and secondary ischemia was varied. When the interval was 72 hr, flaps with secondary ischemia had similar survival to those with primary ischemia. However, when the time interval was 24 hr, flap survival after secondary ischemia was significantly worse than after primary ischemia (p less than 0.01). In Experiment 2, the duration of primary ischemia was varied (15 min, 30 min or 1.5 hr), prior to a fixed interval between primary and secondary ischemia and 5 hr of secondary ischemia. These conditions produced significantly more necrosis than 5 hr of primary ischemia. Thus, even short periods of primary ischemia may have detrimental effects on flap survival after a subsequent period of secondary ischemia. This may have important clinical ramifications.
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1. Biochemical mechanisms of ischaemia were investigated in rabbit skin flaps subjected to 2 h of primary ischaemia then, 24 h later, to 4 h of secondary ischaemia. During secondary ischaemia, flaps underwent either total ischaemia (arterial and venous blood supply occluded) or partial ischaemia (vein only occluded). Some of these flaps were treated at the time of reperfusion with the free-radical scavenger superoxide dismutase (EC 1.15.1.1) and/or the thromboxane synthetase inhibitor UK-38,485. 2. After 30 min of reperfusion, superoxide dismutase treatment significantly reduced blood thromboxane levels, elevated during ischaemia. Superoxide dismutase also reduced tissue levels of malonyldialdehyde and xanthine oxidase, indicators of free-radical damage, and restored the depleted tissue levels of superoxide dismutase. 3. UK-38,485 treatment failed to significantly alter any of these tissue free-radical parameters, although this agent significantly reduced blood thromboxane levels. 4. Combined superoxide dismutase plus UK-38,485 treatment was not significantly better than either treatment alone with respect to any parameter. 5. Partial ischaemia led to consistently higher levels of tissue free radicals and blood thromboxane than did total ischaemia. Thus partial ischaemia appears to result in greater free-radical damage than total ischaemia. 6. These results are consistent with the hypothesis that thromboxane acts as a mediator for free-radical damage in the ischaemic changes within the flap.
The first ischemic insult a tissue suffers is primary (1 degree) ischemia. A second ischemic episode, such as thrombosis after free tissue transfer, may be regarded as secondary (2 degrees) ischemia. Timing relationships were studied in a rodent epigastric-flap model. In a first experiment, the interval between 1 degree ischemia and 2 degrees ischemia was varied. Flaps which had 2 degrees ischemia 12 and 36 hr after the 1 degree episode, had decreased ischemic tolerance, compared with 1 degree ischemic flaps; 2 degrees ischemic flaps, after an interval of 72 hr, had an ischemic tolerance similar to 1 degree ischemic flaps. In a second experiment, the length of the 1 degree ischemia was varied. It was found that as little as 5 min of 1 degree ischemia significantly decreased the subsequent tolerance of 2 degrees ischemia. The possible clinical significance of these results is discussed.
Elevation of a vascular island flap 24 hours before an ischemic insult (prior elevation) has been shown to significantly increase flap survival, and to decrease blood thromboxane levels, compared with acutely ischemic flaps. The current study considered whether prior elevation causes other biochemical alterations that could be beneficial for flap survival. Tissue levels of adenosine triphosphate (a major tissue energy store), superoxide dismutase (a major defense against free radicals), xanthine oxidase (an enzymatic source of free radicals), and edema were measured. Rat epigastric flaps, with or without prior elevation, had 10 or 12 hours of acute ischemia. Biopsies were taken at 0, 12, or 24 hours after reperfusion. Skin from flaps with no ischemia (control flaps) or control skin was harvested at the same times. Acutely ischemic flaps had significantly lower levels of adenosine triphosphate and less edema than those in prior elevated ischemic flaps after 12 hours of ischemia (both, p less than 0.05). Superoxide dismutase and xanthine oxidase did not vary significantly. It is not clear whether the increased adenosine triphosphate level in prior elevated flaps is the cause or the result of increased tissue viability. Prior elevation did not alter free radical mechanisms. Furthermore, prior elevation was beneficial for flap survival despite increased edema.
The possible relationship between increased blood levels of thromboxane (TXA2) and tissue levels of free radicals during ischaemia was investigated. Rabbit epigastric skin flaps were subjected to 4 h of body temperature ischaemia, then infused with either the TXA2 synthetase inhibitor UK-38,485, the free radical scavenger superoxide dismutase (SOD), or both immediately prior to reperfusion. After 30 min of reperfusion, increases in the tissue levels of xanthine oxidase (XO) and malonyldialdehyde (MDA), both of which are indices of free radical generation and decreases in the tissue levels of SOD were found. SOD treatment completely restored XO, MDA and SOD levels to normal, whereas UK-38,485 only partially improved all three parameters. None of these changes was statistically significant. Effluent blood thromboxane B2 (TXB2) levels from the flap increased significantly (P less than 0.01) after ischaemia and were reduced significantly by both UK-38,485 and SOD (P less than 0.05). Combined UK-38,485 and SOD treatment was no better than treatment with either agent alone. ATP levels and oedema, which decreased and increased respectively due to ischaemia, were not significantly altered by drug infusion. These results suggest that free radical damage may be related to TXA2-generated thrombosis in ischaemia/reperfusion injury.
After enucleation, a spherical implant of some material is placed into the muscle cone to give bulk to the orbital socket area. This also allows better movement of the artificial eye prosthesis, which is placed in the socket to give the appearance of a normal eye. If there is loss of the spherical implant because of infection or extrusion for other reasons, there is a resulting enophthalmos of the prosthetic eye. Replacement of this spherical implant with another implant of alloplastic material often results in secondary extrusion. In other cases, there is downward displacement of the spherical implant with pressure against the prosthesis and lower lid. This causes undue stretching of the lower fornix and lid area with inability to hold the prosthesis in place. To correct these two problems, we have found that an autogenous cartilage graft is useful for an implant that will not extrude and that holds its position. Examples of this technique and preoperative and postoperative cases are described here. We have used this technique over the past 11 years and have achieved good success in 15 patients.
Postoperative hematoma is a complication of septal surgery that can be associated with significant morbidity and possibly even mortality in some cases. A simple suction drainage technique using a scalp vein cannula and vacuum tube can prevent a septal hematoma without the need for bulky nasal packing (with its attendant nasal obstruction and risk of bleeding on removal). The technique is also useful for postoperative drainage of an established septal hematoma or abscess secondary to trauma.
Autologous fat grafting, a technique used earlier this century, has recently been proposed for reconstruction of contour defects, especially of the face. A simple technique is described for harvesting fat, removing serum, blood, and liquid fat, and then injecting the concentrated fat into contour defects. Atraumatic harvesting and fat concentration are the keys to greater fat graft survival.
Over the last 14 years, 134 patients with obstructive lymphedema have been treated with microlymphaticovenous anastomoses. Ninety patients were available for long-term follow-up study. Of these, 52 patients were treated by microlymphatic surgery only and 38 of them also had segmental or radical reduction surgery, either at the same time or secondarily. Objective assessment was undertaken by volume and circumferential measurements. Initially, lymphangiography was used, but a study demonstrated increased edema immediately following the investigation in one-third of the patients and it was abandoned, both preoperatively and postoperatively. In the microlymphaticovenous anastomoses only group (N = 52), subjective improvement occurred in 38 patients (73 percent). Objectively, volume changes showed a significant improvement in 22 patients (42 percent), with an average reduction of 44 percent of the excess volume. In the microlymphaticovenous anastomoses and reduction surgery, usually segmental, group (N = 38), subjective improvement occurred in 30 patients (78 percent) and objective improvement occurred in 23 patients (60 percent), with an average reduction of 44 percent of the excess volume. Of those followed up, 67 patients (74 percent) have been able to discontinue the use of conservative measures, with an average follow-up of 4.0 years and average reduction in excess volume of 26 percent. There was a 58 percent reduction in the incidence of cellulitis following surgery. In those patients who were improved, drainage resulted in increased softness of the limbs. Edema of the hand diminished considerably in most patients, although this was difficult to measure. These long-term results indicate that microlymphaticovenous anastomoses have a valuable place in the treatment of obstructive lymphedema and should be the treatment of choice in these patients. Reduction surgery can be used as an adjunct in some of these patients, especially in the posteromedial aspect of the upper arm. Liposuction has been used in failed cases or in patients in whom no lymphatics could be found. Improved results can be expected with earlier operations because patients referred earlier usually have less lymphatic disruption.
The correction of vaginal agenesis requires the creation of a canal that is in the correct axis and ideally of adequate size, texture, and secretion. A simple surgical technique is described which has a good anatomic and functional result with minimal morbidity. It combines the traditional dissection of the rectovesical space described by McIndoe with a significantly modified vulvovaginoplasty based on the Williams method. The technique has been performed with good results and no complications in three patients. Closely monitored vaginal dilatation is essential in the postoperative period. At this stage, only one patient has engaged in intercourse.
Ectropion and scleral show are the most common complications following lower lid blepharoplasty. Certain conditions predispose patients to ectropion, and these should be evaluated. In some cases, the addition of a wedge tarsectomy or tarsal strip procedure to a blepharoplasty in association with careful technique and postoperative measures is important in prevention of postblepharoplasty ectropion. Postoperative ectropion should initially be treated conservatively with massage. This may be effective up to 6 months postoperatively. If conservative measures fail, the etiology of the ectropion should be addressed. Laxity of the tarsus and canthal ligaments benefit from a horizontal lid-shortening procedure. Where there is vertical shortening from excessive skin resection or scarring of the orbital septum, there should be release and grafting of the deficiency.
The harmful effects of the no-reflow phenomenon on skin flaps were modified by using the thromboxane synthetase inhibitor UK-38,485. Sprague-Dawley rats (N = 134) were subjected to either 3 or 5 hours of secondary venous occlusion occurring 24 hours after a primary ischemic episode of 1 1/2 hours. Within each time period, rats received either saline or UK-38,485 at the primary ischemic episode and/or at the secondary ischemic episode. Flaps treated with UK-38,485 in relation to the period of secondary ischemia had a higher survival rate than control ischemic flaps (p less than 0.01). Those treated only at the end of the primary ischemic episode but prior to the secondary ischemic episode had improved survival rates, but these were not statistically significant. These effects may be explained by the lower thromboxane:prostacyclin ratios at the time of revascularization. The possible interrelationship of the prostanoids with free-radical mechanisms in the no-reflow phenomenon is also discussed.
This paper reports the results of a pilot study which examined factors associated with chest infection following head and neck surgery. The overall rate of chest infection was 11%, but was 20% in those patients having a tracheotomy. No infection developed in patients with an intact airway. Other factors which emerged as possibly important were the duration of surgery and heavy regular alcohol intake. We recommend that prophylactic antibiotics be continued for at least 48 h in patients requiring a tracheotomy as part of their head and neck surgery. This is against the trend of shorter antibiotic regimens recommended for prevention of wound infections.