Transdermal suctioning technique for serial sampling of interstitial fluid in newborn infants.

OVERVIEW: Use of a suction-induced epidermal mini-erosion for serial sampling of dermal interstitial fluid (IF) in 16 newborn infants with gestational age ranging from 24 to 42 weeks is reported. RESULTS: The mini-erosion formed reproducibly and electron microscopy showed that the split was located within the epidermis. IF was sampled serially by suctioning during 1-3 days without signs of stress or pain. IF sample volumes (10-50 microl) did not decrease with time. Glucose values in IF and blood were correlated (r(s) = 0.542; p = 0.000). IF glucose was lower than blood glucose on all 3 days. The epidermis regenerated within 4 +/- 0.9 days (mean, SD) after sampling was terminated. There were no complications. CONCLUSION: Serial transdermal sampling was performed without stress or pain in newborn infants. Systemic and temporal differences between glucose measured in IF and blood were observed.

Effect of transcutaneous nerve stimulation on microcirculation in intact skin and blister wounds in healthy volunteers.

Healthy non-smoking volunteers participated in two experimental studies in which the circulatory changes induced by transcutaneous nerve stimulation (TENS) were quantified by two different methods. In experimental series 1 (intact skin), nine volunteers were given TENS on the left lower leg for 60 minutes on three occasions at different frequencies each time (2 Hz, 100 Hz, and sham). Changes in blood flow were assessed by laser Doppler imaging technique every five minutes. The mean blood flow increased by 40% during low frequency TENS and by 12% during high frequency TENS. There was no change in mean blood flow during sham stimulation. In experimental series 2 (blister wound), the circulatory changes induced by TENS were studied by intravital video microscopy and computerised image analysis in standard blister wounds on the lower leg. The microcirculatory blood flow, measured as red blood cell velocity (RBC-V) in 5-14 individual capillaries in each wound, was assessed before and during 45 minutes of TENS (2 Hz and 100 Hz). Mean RBC-V increased by 23% during low frequency TENS (n = 6) and by 17% during high frequency TENS (n = 8). The results show that: laser Doppler imaging and intravital video microscopy techniques can be used to study events at the microcirculatory level; the blister wound is an interesting new standard wound for use in clinical studies; and TENS stimulates the peripheral circulation.

Skin mini-erosion sampling technique: feasibility study with regard to serial glucose measurement.

PURPOSE: To describe a dermally non-invasive serial sampling technique and to test its clinical feasibility with regard to glucose measurement. METHODS: A standardized skin mini-erosion devoid of the epidermal barrier, and covered by an artificial one, was formed by a suctioning technique. Interstitial fluid (IF) was extracted serially by brief application of negative pressure, and its glucose content compared with that in capillary or venous blood samples. RESULTS: The procedure caused no discomfort. The epidermis regenerated rapidly after experimentation. There were no complications. In non-diabetic subjects (n = 13) the mean of all IF values measured daily for 6 days was 6.2 +/- 0.1 mmol/l (+/-SE). The corresponding capillary blood glucose value was 5.6 +/- 0.1 mmol/l, and the venous glucose value was 5.4 +/- 0.1 mmol/l. The differences between IF glucose values and invasive control values remained within narrow limits throughout. The 2SD limits of agreement for the differences were 1.44 mmol/l (IF vs. capillary blood samples) and 1.76 mmol/l (IF vs venous samples) respectively. The OGTT curves suggested glucose kinetics to be similar in IF and in capillary blood. In diabetic subjects, the mean of IF values determined serially during one day was 15.3 +/- 1.0 mmol/l (range, 6.7-21.8 mmol/l), and the corresponding mean capillary value was 12.0 +/- 0.9 mmol/l (range, 3.3-17.2 mmol/l). The ICC for all paired photometric observations was 0.948. CONCLUSIONS: The results suggest the new sampling technique to be a feasible approach for clinical and experimental purposes. A functionally integrated sampling patch is entering the clinical testing stage.

Passive drug diffusion via standardized skin mini-erosion; methodological aspects and clinical findings with new device.

PURPOSE: To develop a clinical alternative to drug administration by injection or infusion. METHODS: A simple, mechanical device (Cellpatch) enables both the formation of a standardized small epidermal bleb and exposure of the circular base of the bleb to drug. The epidermis is split off by suctioning without bleeding or discomfort in a layer superficial to dermal capillaries and nociceptor nerves. Transdermal invasivity is thus avoided. Absorption of dextran test drug in aqueous solution vs molecular weight (3 kDa-70 kDa) and erosion area (3 kDa, diameter: 3-10 mm) were studied in healthy volunteers. The feasibility of using Morphine cellpatch (cell filled with 20 mg/ml morphine hydrochloride, aqueous solution, erosion diameter 6 mm) for post-operative pain relief was studied in two different patient groups; the Cellpatch was removed after 48 hours. Plasma morphine concentrations were determined at intervals. RESULTS: Dextrans of all sizes were efficiently absorbed transdermally, although absorption decreased with increasing molecular weight. The degree of absorption was directly related to the area of the mini-erosion. There were no sign of dose-dumping even with the largest erosions. The Cellpatch performed well in the demanding conditions of the postoperative unit, and was considered easy to use. Pharmacokinetically, the postoperative morphine delivery was related to that of a continuous infusion, with variability and dose in the same range as a continuous morphine infusion used clinically for providing basal pain relief. There were no bacterial growth in the morphine cells at 48 h. Reepithelialization of the erosion was rapid. CONCLUSIONS: The feasibility of administering drugs in a wide size range by passive diffusion through a standardized skin mini-erosion was demonstrated; the rate of absorption decreased with increasing molecular weight. The small area of the erosion restricts and controls the concentration driven diffusion of drug into the circulation. As a consequence of the favorable findings, three placebo-controlled clinical studies using Morphine cellpatch for postoperative pain relief are currently underway.

Absorption of an oxytocin antagonist (antocin) and a vasopressin analogue (dDAVP) through a standardized skin erosion in volunteers.

PURPOSE: Transdermal administration of the peptides [Mpa1, D-Tyr (Ethyl)2, Thr4, Orn8]-oxytocin (antocin) and [Mpa1, D-Arg8]-vasopressin (dDAVP) was studied in healthy volunteers. METHODS: A standardized skin erosion was formed preliminary by suctioning. The peptides were administered in plastic reservoirs through a 5 mm erosion and the absorption was followed for a six-day period with plasma concentration determinations on days 1, 3 and 6 with refilling the reservoirs daily with 15 microns and 10 mM solutions of dDAVP and antocin, respectively. Fourteen healthy non-smoking volunteers divided equally between the sexes, participated in the study. Plasma concentrations were measured using specific radioimmunoassays. Reservoir concentrations and metabolic stability of the peptides were determined using reverse-phase HPLC. RESULTS: Both antocin and dDAVP were absorbed across the skin erosion. The absorption pattern was biphasic with a high initial absorption during days 1 and 2 followed by a lower absorption on days 3 and 6. The absorption on day 1, which was estimated at more than 50% for both peptides during a 24 h period, corresponded to a simultaneous decrease in peptide concentration in the reservoirs. The extent of absorption for antocin on days 3 and 6 was 1/3 to 1/6, respectively, of that observed on day 1. Antocin was minimally degraded in the skin reservoir while dDAVP was intact. However, accumulation of cellular material appeared in the antocin reservoirs. The absorption of antocin was reduced by exposure to intact skin surrounding the skin erosion. No pain was experienced and no scar formation was observed. CONCLUSIONS: The observed biphasic absorption may be a consequence of the mild inflammatory response occurring subsequent to eroding the skin. The standardized skin erosion may provide a route for the short-term delivery of otherwise poorly absorbable peptide and protein drugs.

Transdermal administration of morphine to healthy subjects.

1. Twelve healthy subjects received 10 mg morphine HCl delivered transdermally from an occlusive reservoir applied to a small area of skin, painlessly de-epithelialised by vacuum suction. On a separate occasion, 10 mg morphine HCl was given as an i.v. infusion over 20 min. 2. Venous blood samples were collected serially for 72 h and assayed for morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) by h.p.l.c. Pupil size, salivation, and central nervous effects (nausea, fatigue, headache, feeling of heaviness and dysphoria/euphoria) were also measured. 3. After transdermal application morphine was absorbed by a first-order process to produce relatively constant plasma drug concentrations over 11 h. The absolute bioavailability of transdermal morphine was 75% (65-85%; 95% CI). The plasma concentrations of both M6G and M3G were lower after transdermal administration than after i.v. infusion, and a considerable delay (of up to 1 h) was observed before the metabolites were detectable. AUC ratios for M3G and M6G relative to morphine were similar after both modes of administration. 4. Non-analgesic effects were less pronounced at the lower plasma drug and metabolite concentrations observed after transdermal delivery than after the i.v. infusion of morphine. 5. Transdermal administration of morphine warrants investigation as an alternative route of morphine delivery.

Interpreting laser Doppler recordings from free flaps.

Although the transfer of free flaps is nowadays accomplished with an increasing degree of safety, thrombosis of the microvascular anastomoses is still a problem. In order to avoid delay in re-operating, various methods for objective blood flow monitoring have been tried, among them Laser Doppler Flowmetry (LDF). When one reviews the literature, it is apparent that opinions differ about whether or not LDF is a reliable technique for this purpose. To focus on the need to interpret continuous recordings, this paper reports our findings in six latissimus dorsi free flaps chosen from our series of LDF monitoring procedures. One uneventful flap, no. 1, had an immediate postoperative LDF value of 4.5 perfusion units (PU). LDF values improved during the recovery period and the graphic recording showed fluctuations due to normal physiological variations of the blood flow in the flap. Another uneventful flap, no. 4, showed the same pattern, though at an appreciably lower level, 2 PU, on average. Flap no. 2 had an acceptably high value of 3.5 PU despite suffering a venous thrombosis. However, the LDF recording showed no fluctuations and the value declined gradually. Another flap, no. 3, showed fluctuations and blood flow was normal although the value decreased to 2.5 PU. In flap no. 5, any value between 2 and 3.5 PU could be obtained merely by adjusting the position of the probe in the holder. In no. 6, the LDF value suddenly dropped, accompanied by a decrease in the total amount of backscattered light, indicating venous obstruction which was confirmed at re-operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperbaric oxygen treatment of healthy volunteers with u.v.-irradiated blister wounds.

Healthy male volunteers were wounded by skin blistering, excision of the blister roof and u.v.-irradiation of the dermal wound bed. The lesions, painlessly inflicted on one forearm, were occluded, and no systemic therapy was given (n = 7). Ten days later the procedure was repeated contralaterally, and this time hyperbaric oxygen (HBO) therapy was given (1 h at 283 kPa in a 'multi-place' chamber) beginning 1.5 h, 10.5 h and 21.5 h after injury. The maximum 'length' of the lesions - including the surrounding oedema zone - differed throughout the experiment when comparisons were made on a daily basis (P less than 0.005 on day 1). The values were lower after HBO treatment, the difference being maximal on day 1 when it was 41 per cent. The hyperaemia at the periphery of the lesions, assessed with a mechanical laser Doppler linear scanner, was less in the HBO-treated group on days 3, 4, and 5 (P less than 0.05 on day 3). Centrally within the wound the mean Doppler values were lower after HBO-treatment for the duration of the experiment, but the differences were not significant for comparisons made on a daily basis. The exudation rates decreased after HBO treatment (P less than 0.05 on days 2-6). The end-points of epithelialization (5.1 days (HBO group) vs. 5.7 days) did not differ significantly. Thus, HBO had beneficial effects on this superficial dermal lesion. Oedema and exudation decreased, as did the peripheral hyperaemia, but the rate of epithelialization was not accelerated.

Administration of antidiuretic peptide (DDAVP) by way of suction de-epithelialised skin.

Transdermal drug delivery seems a promising way of achieving complete, predictable absorption, but the epidermis is a barrier for most drugs. A new technique for transdermal drug delivery, in which a small patch of epidermis was removed, was tested in seven healthy volunteers by means of the antidiuretic peptide 1-deamino-8-D-arginine vasopressin (DDAVP). The epithelium of a small area of forearm skin (diameter 5 mm) was removed painlessly, and in a standard way, by a simple device operating at a present vacuum. DDAVP was given by way of improvised occlusive reservoirs. Plasma DDAVP concentration/time curves conformed closely with zero-order kinetics, which suggests that the bioavailability approached 100%, corresponding to that for direct intravenous infusion. Four volunteers were given DDAVP daily for 4 days by way of the de-epithelialised site; there were no signs that re-epithelialisation hindered permeation. All plasma DDAVP values substantially exceeded the lowest effective therapeutic concentration for patients with diabetes insipidus. The vacuum removal of the epithelium caused pronounced hyperaemia in the de-epithelialised dermis (assessed by laser doppler flow measurement); the hyperaemia persisted, unaffected by DDAVP, and may have contributed to the efficient permeation. The skin spot appeared normal at 6 weeks.

Skin suction blister wound exposed to u.v. irradiation: a burn wound model for use in humans.

The effects of exposing blister wounds to u.v. irradiation were assessed in 14 male volunteers, on whose forearms blister wounds (diameter 5 mm, suction set at 200 mmHg below atmospheric for 2 h 15 min, blister roof cut at base), and irradiated blister wounds (as above, in addition u.v. irradiation given selectively for 30 min from a distance of 10 cm), were produced. In non-u.v.-irradiated wounds, flow cessation, assessed by video microscopy (n = 6), was observed in a small proportion of the papillary loop vessels. The oedema adjacent to the wound was poorly developed. Laser Doppler linear scans (n = 8) demonstrated a pronounced hyperaemia in the wound bed and also in the adjacent skin, the reaction subsiding over a few days. The exudation rate, determined by weighing the hydrocolloid dressings applied to the wound, was maximal on day 1 and then rapidly decreased. Epithelialization, assessed evaporimetrically as the time taken for reinstatement of the epidermal water barrier, was complete in 5.1 days. In the u.v.-irradiated wounds the blood flow had ceased in all the papillary loop vessels by day 1, and increased oedema, exudation and hyperaemia at the wound edges were observed. Epithelialization was not significantly retarded by the irradiation injury. After 6 months, slight discolouration of the skin was occasionally observed, but no cosmetically disturbing scars. This benign and standardized wound model in humans--based on a combination of a mechanical suction injury and a superficial radiation burn--may prove to be useful, for instance when studying the effects of burns treatment.

Epithelialization and blood flow in suction blister wounds on healthy volunteers.

Epithelialization and blood flow in painlessly inflicted small suction blister wounds were studied in healthy volunteers (n = 26) using evaporimetry and laser Doppler flowmetry (LDF), respectively. As expected, the evaporation rate normalized faster in wounds covered by an occlusive film than in wounds covered with gauze. The evaporimetry technique was found to be a simple alternative to the biopsy-based methods that have previously been used in humans. Blood flow was increased after 25 min of suctioning, and the hyperemia increased further after equalization to atmospheric pressure. This wound hyperemia (day 1) was more pronounced than that observed during heating of adjacent skin, and more pronounced at a pressure of 400 mm Hg below atmospheric pressure than at 200 mm Hg below. The hyperemic response lasted for some days and was similar on arm and foot. A mechanical LDF linear scanner was used to create a flow profile across the wound into the adjacent skin. Six months after inflicting the lesions there was no visible scar. The findings suggest that this blister wound model may be useful for studying epithelialization and microcirculatory events after trauma and during early wound healing in humans.

Correction of breast ptosis utilizing a "fold over" de-epithelialized lower thoracic fasciocutaneous flap.

In the operation described, vascularized dense connective tissues, consisting of two layers of dermis or fascia, are supplied from below the inframammary fold and shaped surgically into a supportive subcutaneous "cup." The reconstruction adds to the effect of the dermal mastopexy for the treatment of breast ptosis. This fasciocutaneous type of flap also augments the breast, and a pleasing projection may be achieved without resorting to an implant. The degree of augmentation depends upon the thickness of the subcutis donor site.

Advancement flaps for alar reconstruction.

Advancement flaps were used for reconstruction of a full-thickness and a partial-thickness rectangular defect limited to a part of the nasal ala. The flap's base in the medial cheek was locked into a forward position by elimination of a Burow triangle from the nasolabial fold.

An angiographic technique for three-dimensional determination of arterial supply patterns in cadaver soft tissue.

A method for arterial tree mapping that can be used in cadaver soft tissue is presented. In situ angiograms and photographs are supplemented with profile angiograms of relatively narrow bands of tissue from the removed specimen. The described method was better suited for mapping the course and supply patterns of a soft-tissue arterial network than either in situ angiograms or dissection. While practical problems were encountered with most of the solutions used for providing radiopacity or structural support to the vessels, pure barium sulfate was found to be suitable because it filled the vascular tree to the capillary level without leakage during excision of the specimen.

Skin perfusion pressure assessed by measuring the external pressure required to stop blood cell flux.

Laser Doppler flowmetry (LDF) was used to determine the point at which blood flow cessation is achieved under circumferentially applied external counter pressure at the ankle level. In 13 individuals with a normal ankle index, the flow of cessation external pressure (FCEP) was, on average, 28 mmHg lower than the systolic ankle pressure (range: 7-62). In 19 patients with an ankle index below 1.0, FCEP correlated with the ankle pressure (rs = 0.76) and even more closely with the ankle index (rs = 0.82). In patients with a more pronounced degree of arterial occlusive disease, FCEP can be equal to or even higher than the ankle pressure. This may be due to a release of sympathetic vasoconstrictor tone and possibly to the presence of a collateral circulation supplying the skin. Individual LDF values from the skin at rest do not reflect the degree of peripheral circulatory insufficiency.

Continuous wound irrigation in the pig.

It was demonstrated in the pig that full-thickness wounds in the skin can be continuously treated by irrigation for several days. Irrigation was accomplished through a porous, occlusively applied dressing having two ports, one for supply and one for drainage. The fluid, delivered by means of an iv set, was sucked through the inert dressing, leaving it partially saturated, and with fluid spread evenly through its pores. Particulate matter was removed along narrow paths converging on the outlet, not showing any significant diversion. The apparatus for fluid supply and drainage was arranged to move with the animal, thus eliminating the risk of obstruction of the tubes as a result of twisting. The fluid was eliminated by one suction line, and the vacuum in the dressing maintained by another. This allowed the suction to be adjusted to a level near the atmospheric pressure.

Staphylococcal wound infection in the pig: Part I. Course.

Full-thickness excision wounds infected with Staphylococcus hyicus, a pig pathogen, or Staphylococcus aureus, a human pathogen, were produced in pigs. The inoculated wounds were kept occluded for 2 days and then exposed and biopsied at intervals for 9 to 12 days. The exposed lesions were edematous and exudative. The S. aureus model was experimentally advantageous because the infection remained localized to the wound without systemic infection or signs of discomfort. The S. hyicus infection caused a rash with skin blisters; thus, its use is discouraged. The concentration of S. hyicus in the wound on day 2 was log 8.6 +/- 0.4 CFU/g (mean +/- standard deviation). On day 4 the mean was log 9.2. For S. aureus the values were log 8.0 +/- 0.9 on day 2 and 6.9 on day 4 (p less than 0.05). Of the 50 individual values in the S. aureus series, 45 were above log 5. The inflammatory reaction was more pronounced after the infection with S. hyicus, whereas with S. aureus the fibroblast response came earlier and was more pronounced. The model parallels typical clinical courses of staphylococcal infection.

Staphylococcal wound infection in the pig: Part II. Inoculation, quantification of bacteria, and reproducibility.

Bacteria from full-thickness excision wounds with staphylococcal infection in the pig were cultured quantitatively. The bacterial concentration increased with the size of the inoculum, and after 2 days it had already reached a stable, maximal level of approximately log 8 CFU/g in the tissue. The correlation coefficient was 0.753 in comparing concentrations from superficial and deep biopsy halves and 0.145 from "surface wash" and superficial biopsies. The "within wound" sample distribution was logarithmic. The gain in precision when assessing the mean bacterial concentration from three instead of one biopsy was 45%. The coefficient of variation of between wound and within wound determinations was in the same range (i.e., 7.1-12.5%). Paired observations from a sample population with 7 sites (wounds) were needed to determine a 10% change in the bacterial concentration at a significance level of p less than 0.05, and a similar change could be determined from unpaired observations based on two populations with eleven sites.

A device for noninvasive assessment of perfusion pressure in the skin of healthy volunteers.

A device allowing pressure to be applied to a local skin site where the skin blood flow is followed using laser Doppler flowmetry is described. The blood flow was studied on the back of the hand in eight volunteers before and during brachial arterial occlusion and while the external pressure was increased step by step. The flowmetry value during arterial occlusion was 0.3 +/- 0.1 AU, and when the external pressure was increased to 120 mm Hg the values were similar (p = .44). The skin perfusion pressure, defined as the least external pressure needed to achieve flow cessation, was found to be 92 +/- 16 mm Hg (range 70-111 mm Hg), and the mean arterial pressure was 90 +/- 9 mm Hg (NS). The skin perfusion value is in agreement with that found by others using other techniques for measuring blood flow and a circumferent cuff for applying pressure.