Biomedical subjects

P K Maitz

Publications and source records attributed to P K Maitz.

10 recordsLinked to original sources

PubMed1999

Free-flap transfer with a synthetic arterial pedicle.

In this study, a unilateral epigastric free flap was raised in 12 rabbits. After the arterial portion of the flap (the superficial femoral artery) was replaced by a 1-cm-long polytetrafluoroethylene graft with an internal diameter of 1 mm, the flap was revascularized by two conventional microvascular end-to-end anastomoses (graft to artery and vein to vein). At 3 weeks, all flaps were raised again and the patency of the polytetrafluoroethylene grafts was checked. All grafts, including the proximal and distal anastomoses, were harvested and processed for light and electron microscopy. All grafts remained patient, and all flaps survived the period of 3 weeks. At reexploration, the graft was completely covered with connective tissue. Light and scanning electron microscopy evaluation showed that the internal surface of the graft was covered by a fibrin layer, and that the ingrowth of neoendothelium had just started from both anastomotic sites. The use of small-diameter polytetrafluoroethylene grafts in a rabbit free-flap model was demonstrated to be a reliable alternative for pedicle elongation.

Animals↗

PubMed1999

Sutureless microvascular anastomoses by a biodegradable laser-activated solid protein solder.

A new sutureless technique to successfully anastomose the abdominal aorta of rats (1.3 mm in diameter) by using a fully biodegradable, laser-activated protein solder is presented. A total of 90 rats were divided into two groups randomly. In group one, the anastomoses were performed by using conventional microsuturing technique, whereas in group two, the anastomoses were performed by using a new laser welding technique. In addition, each of the two groups were divided into five subgroups and evaluated at different follow-up periods (10 minutes, 1 hour, 1 day, 1 week, and 6 weeks). At these intervals, the anastomoses were evaluated for patency and tensile strength. Three anastomoses in each subgroup were processed for light and electron microscopy. All anastomoses were found to be patent. The mean clamp time of the anastomoses performed with conventional suturing was 20.6 minutes compared with 7.2 minutes for the laser-activated welded anastomoses (p < 0.001). The strain measurements showed a stronger mechanical bond of the sutured anastomoses in the initial phase. However, at 6 weeks the tensile strength of the laser-welded anastomoses was higher compared with the conventional suture technique. Histologic evaluations revealed a near complete resorption of the solder after 6 weeks. The junction site of the vessel ends cannot be determined on the luminal side of the artery. In conclusion, a resorbable protein used as a solder, activated by a diode laser, can provide a reliable, safe, and rapid arterial anastomosis, which could be performed by any microsurgeon faster than conventional suturing after a short learning curve.

Anastomosis, Surgical↗

PubMed1998

[Analysis of hand function with the Millesi examination scale in patients with pollicisation after aplasia or hypoplasia of the thumb].

Pollicisation of a single long finger is the method of choice to treat congenital thumb aplasia or thumb hypoplasia. Using Millesi's scale for the functional analysis of the hand, we examined six patients treated in the years 1983 to 1994 in our service. Average age at the time of surgery was 2.4 years and the follow-up time was seven years on average. Of the six patients, four suffered from additional malformations of the ipsilateral arm. These anomalies required early surgical treatment and therefore delayed the pollicisation procedure. The results of the anatomical part of the examination ranged between 39 and 94% of the achievable value. The final results including sensibility, strength, and skills reached 11 to 50%. Development of skills and muscle strength in the operated hand was dependent on the follow-up time. Millesi's scale could be applied successfully in this special group of children with congenital malformation of hands.

Child↗

PubMed1996

Impact of tissue expansion on flap prefabrication: an experimental study in rabbits.

This study was designed to determine whether tissue expansion after vascular pedicle implantation would increase the survival area of prefabricated skin flaps. In 20 New Zealand white rabbits, the vascular pedicle consisting of the central artery and vein of the left ear was implanted into the neck. At the time of pedicle implantation a subcutaneous pocket was created measuring 5 x 14 cm beneath the implantation site. Tissue expanders of three different sizes and volumes were implanted in the rabbits of three treatment groups. No tissue expander was implanted in the animals of the control group. All flaps were transposed after 3 weeks to the contralateral ear, and flap survival was assessed 1 week later. The increased area of the flap survival was statistically significant in all three treatment groups compared to the nonexpanded flaps (P = 0.003, P = 0.004, P < 0.0001, respectively). In addition there was a statistically significant larger area of survival using a 100-cc expander measuring 5 x 14 cm (the same size as the elevated flap) compared to 40-cc (3 x 5 cm) or to 60-cc (4 x 8 cm) expanders (P < 0.001, P = 0.004, respectively). The one-way analysis of variance and the t-test were used to show statistical differences. We conclude that the time necessary for neovascularisation of the skin flap could be used to expand the tissue, not only increasing the amount of available tissue, but also enhancing the vascularity.

Analysis of Variance↗

PubMed1996

Maximizing flap survival in a prefabrication model using exogenous and endogenous bFGF: a new approach.

Flap prefabrication is dependent on the neovascular response that occurs between the implanted arteriovenous pedicle and the recipient tissue. Augmentation of this neovascular response with angiogenic growth factors would maximize flap survival and minimize the interval between pedicle implantation and flap rotation. Maximizing the biologic activity of endogenous growth factors would likewise positively impact upon flap survival. This study examined the role of basic fibroblast growth factor, a known potent angiogenic growth factor, on flap survival in a rabbit ear prefabrication model. Sucrose octasulfate, a substance that binds basic fibroblast growth factor, stabilizes it, and protects it from degradation, was also studied to determine its impact on flap survival. Flap survival was increased using basic fibroblast growth factor, sucrose octasulfate, and the two substances combined together. The use of substrates designed to maximize the biologic activity of endogenous growth factors, rather than relying on the artificial addition of exogenous growth factors, represents a new approach in the search for methods that will improve flap survival.

Animals↗

PubMed1996

Pharmacodynamics of mivacurium in severely burned patients.

The pharmacodynamics of mivacurium, a new short-acting non-depolarizing muscle relaxant, were studied in nine severely burned patients with concomitant inhalation injury. Complete neuromuscular blockade was achieved within 1.3 min (controls 3.0 min) following the usually recommended intubating dose (0.15 mg/kg/BW 2 x ED95) of mivacurium. The clinical duration of neuromuscular blockade and the recovery times were slightly prolonged, due to significantly reduced serum cholinesterase activity (clinical duration 24.6 min vs. 15.3 min). This pharmacodynamic profile makes mivacurium preferable for intermittent on-demand neuromuscular blockade in the severely burned patient.

Adult↗

PubMed1994

Manipulating prefabricated flaps: an experimental study examining flap viability.

As flap prefabrication becomes a more commonly used clinical tool, it is necessary to investigate the limitations of this technique. Reconstructive procedures of the face often require "custom fitted" flaps to satisfy esthetic demands. This study examines and compares the safety of manipulating thin prefabricated skin flaps versus established axial pattern skin flaps. Twenty-seven New Zealand white rabbits were used to determine if prefabricated flaps can be folded 180 degrees around the edge of the rabbits' ears. The survival of these folded prefabricated flaps was compared with the survival of axial pattern flaps sutured into an identically recipient site. In addition, flaps prefabricated in the same manner were sutured onto a straight recipient bed to evaluate the viability of the newly vascularized tissue. The folded prefabricated flaps had reduced survival (56%) compared to equivalent folded axial pattern flaps (85%), P < 0.005. The nonmanipulated prefabricated flaps and axial pattern flaps survived completely.

Animals↗

PubMed1994

Flap prefabrication using the "vascular crane" principle: an experimental study and clinical application.

Techniques for tissue transfer have continued to evolve. Free flap prefabrication represents a further progression of well known plastic surgery principles in the arena of tissue transfer. This report presents an experimental study demonstrating that the repeated use of a vascular pedicle to prefabricate flaps in the rabbit is possible. There is a decrease in flap viability with the second transfer. A clinical case using this repeated transfer or "crane" principle is also reported. We conclude that the repeated use of a vascular pedicle to prefabricate multiple flaps is a viable option in selected cases.

Adult↗

PubMed1994

The value of the delay phenomenon in flap prefabrication: an experimental study in rabbits.

Neovascularisation of thin skin flaps after arteriovenous pedicle implantation (flap prefabrication) and the impact of the delay mechanism on the viability of these flaps were investigated. Twenty-four full thickness skin flaps were raised in twelve New Zealand white rabbits. Delay incisions were made at the lateral borders of the planned flaps at the same time as pedicle implantation, 1 week before pedicle implantation, or 1 week after pedicle implantation and the flaps based on the implanted vessels raised at 2 weeks after implantation. Flap survival assessed at 1 week was found to be improved when flap delay was performed 1 week before or after pedicle implantation. Angiographic studies demonstrated an increased density and linearity of the vascular pattern in these delay group flaps. The combination of the time-tested concept of delaying a flap with the newer technique of flap prefabrication appears to improve flap viability.

Angiography↗

PubMed1993

Flap prefabrication using an exteriorised vascular pedicle in a rabbit ear model.

We have developed a new model of thin flap prefabrication in the rabbit with an exteriorised vascular pedicle in a skin tube. Study of these prefabricated flaps after transfer demonstrated that distal flap survival improved as the interval between implantation and flap transfer increased. Exteriorising the pedicle minimises both donor deformity and pedicle trauma and allows easier experimental study of the neovascularisation process in flap prefabrication.

Animals↗