The pharmacokinetics of transdermal fentanyl delivered with and without controlled heat

Preliminary reports have demonstrated that the application of local heat to the transdermal fentanyl patch significantly increased systemic delivery of fentanyl. The objective of this study was to further evaluate the pharmacokinetic effect of local heat administration on fentanyl drug delivery through the transdermal fentanyl patch delivery system in volunteers. In addition, the study was intended to document the effect of heat on steady-state transdermal fentanyl delivery. This was an open, 3-period, crossover study that evaluated the pharmacokinetics and safety of 25 microg/h transdermal fentanyl administered with and without local heat. During Sessions A and B, subjects received transdermal fentanyl for a 30-hour period. During Session A, heat was applied for 1 hour at the 24-hour time point during the 30-hour period. During Session B, heat was applied for the first 4 hours and then again for 1 hour at the 24-hour time point during the 30-hour period. The order of Sessions A and B was randomized, and a minimum of 2 weeks separated the sessions. Five of the 10 subjects returned to participate in Session C. During Session C, subjects received transdermal fentanyl 25 microg/h for 18 hours. Heat was applied during the first 4 hours of administration and then again for 15-minute periods at the 12- and 16-hour time points. Arterial blood samples for determination of serum fentanyl concentration were collected. Maximum concentration (C(max)), time to maximum concentration (t(max)), and area under the curve (AUC) were determined for each treatment period. Sedation, vital signs, oxygen saturation, and adverse events were recorded. During a period of 36 hours, there were no significant differences in C(max), AUC, or T(max) between transdermal fentanyl delivery with no heat and heat. However, significant differences were seen during the first 4 hours, with C(max) and AUC values almost 3 times higher for the heated administrations than for the administrations without heat. With heat, the mean C(max) was 0.63 ng/mL compared with a C(max) of 0.24 ng/mL without heat (P =.007). With early heat, the mean AUC was 1.22 ng/mL. h compared with 0.42 ng/mL. h without heat (P =.003). There was no statistically significant difference between the median times to achieve peak values (T(max)) during the first 4 hours. The addition of heat at 24 hours resulted in rapid increases in serum fentanyl concentrations for both groups and higher serum fentanyl concentrations for the administration that did not receive heat previously. Applying heat for 15 minutes at the 12-hour and 16-hour time points produced a rapid but short duration increase in serum fentanyl concentrations. The results suggest controlled heat might be used to significantly shorten the time needed to reach clinically important fentanyl concentrations. Controlled heat might be useful to produce rapid increases in serum concentrations for the rapid treatment of breakthrough pain.

Clinical evaluation of the Life Support for Trauma and Transport (LSTAT) platform

INTRODUCTION

The Life Support for Trauma and Transport (LSTAT trade mark ) is a self-contained, stretcher-based miniature intensive care unit designed by the United States Army to provide care for critically injured patients during transport and in remote settings where resources are limited. The LSTAT contains conventional medical equipment that has been integrated into one platform and reduced in size to fit within the dimensional envelope of a North Atlantic Treaty Organization (NATO) stretcher. This study evaluated the clinical utility of the LSTAT in simulated and real clinical environments. Our hypothesis was that the LSTAT would be equivalent to conventional equipment in detecting and treating life-threatening problems.

METHODS

Thirty-one anesthesiologists and recovery room nurses compared the LSTAT with conventional monitors while managing four simulated critical events. The time required to reach a diagnosis and treatment was recorded for each simulation. Subsequently, 10 consenting adult patients were placed on the LSTAT after surgery for postoperative care in the recovery room. Questionnaires about aspects of LSTAT functionality were completed by nine nurses who cared for the patients placed on the LSTAT.

RESULTS

In all of the simulations, there was no clinically significant difference in the time to diagnosis or treatment between the LSTAT and conventional equipment. All clinicians reported that they were able to manage the simulated patients properly with the LSTAT. Nursing staff reported that the LSTAT provided adequate equipment to care for the patients monitored during recovery from surgery and were able to detect critical changes in vital signs in a timely manner.

DISCUSSION

Preliminary evaluation of the LSTAT in simulated and postoperative environments demonstrated that the LSTAT provided appropriate equipment to detect and manage critical events in patient care. Further work in assessing LSTAT functionality in a higher-acuity environment is warranted.

Evaluation of an electronic esophageal detector device in patients with morbid obesity and pulmonary failure

OBJECTIVE

Undetected esophageal intubation can result in permanent injury or death. Clinical confirmation of tube location may be misleading. Adjunctive methods should be used to supplement clinical judgment. Unfortunately, end-tidal carbon dioxide may misidentify properly placed tracheal tubes in low perfusion situations, while esophageal detector devices (EDDs) may misidentify properly placed tracheal tubes in situations where little airway dead space exists (morbid obesity, pulmonary failure). This study evaluated a modified EDD (the electronic esophageal detector device, or EEDD) designed to eliminate the problem of misidentified tracheal intubations.

METHODS

Intubated morbidly obese or pulmonary failure patients were eligible for study entry. All endotracheal tubes (ETTs) were confirmed to be tracheal by waveform capnography and clinical judgment prior to study entry. Following consent, all patients were attached to the EEDD and a "measurement" was made to determine the "location" of their ETTs. Probability of misidentifying a tracheal intubation in these high-risk populations was calculated using a log-normal distribution method.

RESULTS

Twenty-seven morbidly obese patients and 37 pulmonary failure patients were entered. The EEDD correctly identified all tracheal intubations in these patients, giving a false-negative rate of zero. The probability of misidentifying a tracheal intubation in the combined group was 0.06%.

CONCLUSION

This study demonstrates that the EEDD reliably identifies tracheal intubations in situations where standard EDDs may fail. However, future studies must determine the reliability of this device for identification of esophageal intubations and the reliability of this device in the less controlled emergency department and prehospital settings.

The effects of interferon-alpha/beta in a model of rat heart transplantation

Interferons have multiple immunologic effects. One such effect is the activation of expression of cell surface antigens. Interferon alpha/beta enhance expression of class I but not class II histocompatibility antigens. Contradictory information has been published regarding the effect of interferon-alpha/beta administration in patients with kidney transplantation. In a model of rat heart transplantation we demonstrated that administration of interferon-alpha/beta accelerated rejection in a dose-dependent fashion in the absence of maintenance cyclosporine. Animals treated with maintenance cyclosporine had evidence of increased rejection at 20 days that was resolved completely at 45 days with cyclosporine alone.

Flow cytometric analysis of human erythrocytes: II. Possible identification of senescent RBC with fluorescently labelled wheat germ agglutinin

In the first paper of a series (Gutowski, et al., 1991) we discussed the use of flow cytometry to follow at the cellular level the aging of red blood cells (RBC) in circulation, using fluorescently labelled lectins and goat anti-human-IgG and -IgM. The Coulter Epics 541 was used for those studies. In this report we describe more extensive experiments using the Becton-Dickinson FACScan flow cytometer, and compare the results with those obtained with the Coulter Epics 541. By changing sample conditions from isotonic to hypotonic, compensation for differences of the two instruments was accomplished. We confirmed our previous observations that RBC react very strongly with fluorescein isothiocyanate labelled wheat germ agglutinin (FITC-WGA) and that there is little change in the intensity of fluorescence given by RBC of all sizes with the exception of the smallest. Reactivity with FITC-WGA is markedly decreased in the presence of competitive inhibitors of sialic acid or upon enzymatic removal of sialic acid from RBC. Removal of sialic acid is accompanied by increased reaction with peanut agglutinin (FITC-PNA). Flow cytometry was also used to monitor the enrichment of a population of smallest RBC (less than 0.05%), isolated from both counterflow centrifugation and the interface obtained from Histopaque separation. These smallest RBC showed low reactivity with FITC-WGA and higher binding of FITC-goat-anti-human-IgG, and -IgM, and therefore represent the most senescent RBC, just prior to their clearance from circulation by the reticuloendothelial system. These observations are in compliance with the hypothesis that physiological desialylation of glycophorin is responsible for clearance of senescent RBC from circulation (Aminoff, 1988).

Digital venous anatomy

The veins of the digits and their valves were studied in nine cadaveric hands by sequential angiography, microdissection, routine histology, cross-sectional microradiography, and corrosion casting. The findings revealed a pattern of dorsal venous arches situated over each digit. Connections between those arches were at the level of the metacarpal heads, the point at which most of the palmar venous blood joins the dorsal system by intercapitular veins. A system of valves, which were arranged so as to direct flow from distal to proximal, from palmar to dorsal, and from radial to ulnar in the hand, was present in all veins as far distal as the pulp.

Ectopic subgaleal meningioma and familial neurofibromatosis

A 14-year-old male adolescent presented with progressive enlargement of the forehead and a history of familial neurofibromatosis. Plain x-ray films of the skull, computed tomography scanning, and carotid angiography were performed prior to removal of the tumor. Pathologic verification of an ectopic subgaleal meningioma prompted the report of this rare tumor.

Intercostal nerve transfer in brachial plexus injuries: an experimental study

Eighteen adult mongrel dogs underwent unilateral surgical disruption of the brachial plexus. Twelve animals (Group I) had as a second-stage procedure transfer of T4 and T5 intercostal nerves and their accompanying vascular bundles to the distal musculocutaneous nerve stump. Six animals (Group II) had restoration of musculocutaneous nerve continuity with conventional interpositional sural nerve cable grafts. Group I animals demonstrated significantly better electromyographic evidence of reinnervation and, comparing appearance and weight of operated and unoperated biceps muscles at the time of animal sacrifice, maintained greater gross weight and more normal overall appearance of muscle. Histologic study of muscle tissue showed no significant difference between the two groups whereas musculocutaneous nerve histology distal to all anastomoses revealed less fibrous tissue and a greater number of healthy-appearing axons in Group I. It is concluded that vascularized intercostal nerve transfer as performed in this study has theoretical advantages over conventional nonvascularized intercostal nerve transfer but additional investigation is required to make this determination. The superiority of vascularized intercostal nerve transfers over conventional interpositional sural nerve cable grafts has been demonstrated.

Renal amyloidosis associated with systemic lupus erythematosus

A renal biopsy of a patient who had systemic lupus erythematosus and proteinuria revealed the presence of both amyloidosis and lupus glomerulonephropathy. The association between secondary amyloidosis and systemic lupus erythematosus has only been reported in four previous cases. The significance of this association is discussed.

Hemoglobin Louisville (beta-42 (CD1) phe-leu): an unstable variant causing mild hemolytic anemia

An unstable hemoglobin variant termed Hb Louisville, was found in four members of a Caucasian family, who were suffering from a mild hemolytic anemia. The variant showed a decreased stability upon warming at 65 degrees C and an increased tendency to dissociate in the presence of sulfhydryl group-blocking agents. The structural abnormality was identified as a replacement of phenylalanyl residue in position 42 (CD1) by a leucyl residue. Substitution of this phenylalanyl residue, which participates in the contact with heme, by a nonpolar leucyl residue has apparently less severe consequences than a replacement of the same residue by a polar seryl residue as in Hb Hammersmith. Oxygen equilibrium studies of total hemolysate from one Hb Louisville heterozygote indicated a decreased oxygen affinity, a marked decrease in heme-heme interaction, and a normal Bohr effect. Studies with isolated Hb Louisville were not made because it was not possible to separate the variant from normal Hb A.