Pedicled prelaminated capsular flaps for coverage of skin defect in a rat model.

SUMMARY: In reconstructive surgery defects are closed using pedicled or free flaps. By raising these flaps the reconstructive surgeon creates new defects, which in turn are closed primarily or with the use of skin grafts. Inevitably, this results in extra scars that may be visible and may also lead to diminished function. In an attempt to avoid full-thickness donor site skin defects in reconstructive surgery, the principle of prefabrication has been modified to produce capsular flaps. In a rat model, we created prefabricated and prelaminated pedicled capsular flaps to fill a full-thickness skin defect. Both femoral vascular bundles in 10 Wistar rats were sandwiched between two silicone sheets. The capsule formed between the two sheets received its main blood supply from this vascular pedicle, and was used as carrier for a skin graft. After ligation of the distal femoral vessels a pedicled prelaminated capsular flap was raised on the proximal femoral vessels. The flap was brought to the surface for closure of an experimentally created abdominal skin defect. All 20 flaps survived, and there were no surgery-related complications. Comparison with controls indicated that flap survival was attributable to the blood supply from the vascular axis. Pedicled prelaminated capsular flaps can be created reliably and reproducibly, confirming the results of earlier studies, and are of value in reconstructive surgery.

Formation of a reliable capsular flap in a rat model.

UNLABELLED: Prefabrication can be used to produce capsular flaps; other researchers have confirmed the feasibility of such flaps. Before the possibilities of capsular flaps can be explored, a reliable method to create these flaps has to be established first. METHODS: To produce capsular flaps in a rat model, the femoral vascular bundle was sandwiched between two silicone sheets. Three different methods were used and described. The capsule that formed between the two silicone sheets receives its main blood supply from that vascular pedicle. In this way pedicled capsular flaps were created. These flaps were used as a carrier for a skin graft, thus pre-laminating them, to test their ability for reconstructive surgery. The results of the three different methods of creating capsular flaps in a rat model were described and their results were evaluated. Especially the amount of capsule formation and the viability of the skin grafts was observed and compared. The feasibility of pre-laminated capsular flaps is confirmed and the most reliable method of creating them is described.

A small pit emptying machine: an appropriate solution for a Nairobi slum.

This article describes the results of the trial period of a pedestrian-controlled pit emptying machine. This 'vacutug' has been tested for UNCHS (Habitat) in a low-income settlement in Nairobi, Kenya, through a local NGO. The trial confirmed the viability of the principle of the vacutug as the machine has been in operation for two and a half years. Repairs have been made locally out of income from the service, spare parts can be obtained and demand for the service is high. Although the cost of the service has already been raised, demand has not been reduced. The technical improvements which need to be made can be incorporated in the design, and the next batch of machines is being constructed for further trials. Management of the service is critical for financial sustainability and even during the trial of the technology, the management aspects have been the most difficult of the service.

Pharmacokinetics and pharmacokinetic-dynamic relationship between rapacuronium (Org 9487) and its 3-desacetyl metabolite (Org 9488).

UNLABELLED: Rapacuronium (Org 9487) is a rapid-onset and short- to intermediate-acting muscle relaxant. Its 3-desacetyl metabolite, Org 9488, also exerts neuromuscular-blocking activity that may become apparent after prolonged maintenance of relaxation with rapacuronium. In this study, the pharmacokinetic behavior (n = 7) of this metabolite and the pharmacokinetic/pharmacodynamic (PK/PD) relationship of rapacuronium (n = 10) and Org 9488 (n = 7) were investigated in humans. Similar protocols were used for three study groups regarding the anesthetic technique, blood and urine sampling, and pharmacokinetic and PK/PD analyses. The time course of action was measured mechanomyographically using the adductor pollicis muscle. The median clearance of rapacuronium was 7.28 mL x kg(-1) x min(-1) x with an excretion fraction in the urine of 6.2%. The clearance (studied in two groups) of Org 9488 was 1.28 and 1.06 mL x kg(-1) x min(-1) with an excretion fraction in the urine of 51.9% and 53.5%, respectively. The median rate constant of transport between plasma and the biophase of rapacuronium (0.449 min(-1)) is markedly larger than that for Org 9488 (0.105 min(-1)). The modeled concentration in the biophase at 50% effect as a measure of potency is higher for rapacuronium (4.70 microg/mL) than for Org 9488 (1.83 microg/mL). The lower clearance of the metabolite will gradually prolong the time course of the neuromuscular blockade during maintenance with rapacuronium. IMPLICATIONS: We investigated the concentration-time-effect relationship of the relaxant rapacuronium and the contribution of its metabolite. Clearance, rate constant of transport between plasma and the biophase, and modeled concentration in the biophase at 50% effect of rapacuronium are consistent with its rapid onset and short to intermediate duration. The lower clearance of the metabolite will gradually prolong the time course of the neuromuscular blockade during maintenance with rapacuronium.

Cardiovascular effects of an intubating dose of rocuronium 0.6 mg kg-1 in anaesthetized patients, paralysed with vecuronium.

We have studied, in adult patients, ASA I-II, the cardiovascular effects of an intubating dose of rocuronium 0.6 mg kg-1. After induction, patients were paralysed with vecuronium and the trachea intubated. Heart rate (HR) and non-invasive mean arterial pressure (MAP) were measured every 1 min. After stabilization of HR and MAP, defined as < 3% change over three measurements, rocuronium (n = 20) or saline (n = 10) was injected at random. Mean HR increased initially from 66.6 to 72.1 beat min-1, 4 min after rocuronium, and then decreased gradually to 69.6 beat min-1, that is a net increase of 3.3 beat min-1 over 10 min (P < 0.001), whereas after saline there was a gradual decrease from 65.8 to 60.9 beat min-1 (P < 0.001) over 10 min. From the third minute, HR was significantly higher in the rocuronium group. Mean MAP decreased in both groups within 10 min to a similar extent after rocuronium and saline, that is from 74.9 to 72.1 mm Hg and from 74.7 to 72.2 mm Hg, respectively (both P < 0.001). There were no differences in MAP at any time between the rocuronium and saline groups. We conclude that an intubating dose of rocuronium, in the absence of haemodynamic effects related to paralysis itself, resulted in a limited increase in HR without change in MAP, probably because of its weak vagolytic activity.