Chain transplantation: initial experience of a large multicenter program.

We report the results of a large series of chain transplantations that were facilitated by a multicenter US database in which 57 centers pooled incompatible donor/recipient pairs. Chains, initiated by nondirected donors, were identified using a computer algorithm incorporating virtual cross-matches and potential to extend chains. The first 54 chains facilitated 272 kidney transplants (mean chain length = 5.0). Seven chains ended because potential donors became unavailable to donate after their recipient received a kidney; however, every recipient whose intended donor donated was transplanted. The remaining 47 chains were eventually closed by having the last donor donate to the waiting list. Of the 272 chain recipients 46% were ethnic minorities and 63% of grafts were shipped from other centers. The number of blood type O-patients receiving a transplant (n = 90) was greater than the number of blood type O-non-directed donors (n = 32) initiating chains. We have 1-year follow up on the first 100 transplants. The mean 1-year creatinine of the first 100 transplants from this series was 1.3 mg/dL. Chain transplantation enables many recipients with immunologically incompatible donors to be transplanted with high quality grafts.

Managing finances of shipping living donor kidneys for donor exchanges.

Kidney donor exchanges enable recipients with immunologically incompatible donors to receive compatible living donor grafts; however, the financial management of these exchanges, especially when an organ is shipped, is complex and thus has the potential to impede the broader implementation of donor exchange programs. Representatives from transplant centers that utilize the National Kidney Registry database to facilitate donor exchange transplants developed a financial model applicable to paired donor exchanges and donor chain transplants. The first tenet of the model is to eliminate financial liability to the donor. Thereafter, it accounts for the donor evaluation, donor nephrectomy hospital costs, donor nephrectomy physician fees, organ transport, donor complications and recipient inpatient services. Billing between hospitals is based on Medicare cost report defined costs rather than charges. We believe that this model complies with current federal regulations and effectively captures costs of the donor and recipient services. It could be considered as a financial paradigm for the United Network for Organ Sharing managed donor exchange program.

Transporting live donor kidneys for kidney paired donation: initial national results.

Optimizing the possibilities for kidney-paired donation (KPD) requires the participation of donor-recipient pairs from wide geographic regions. Initially it was envisaged that donors would travel to the recipient center; however, to minimize barriers to participation and simplify logistics, recent trends have involved transporting the kidneys rather than the donors. The goal of this study was to review outcomes of this practice. KPD programs throughout the United States were directly queried about all transplants involving live donor kidney transport. Early graft function was assessed by urine output in the first 8 h, postoperative serum creatinine trend, and incidence of delayed graft function. Between April 27, 2007 and April 29, 2010, 56 live donor kidneys were transported among 30 transplant centers. Median CIT was 7.2 h (IQR 5.5-9.7, range 2.5-14.5). Early urine output was robust (>100 cc/h) in all but four patients. Creatinine nadir was <2.0 mg/dL in all (including the four with lower urine output) but one patient, occurring at a median of 3 days (IQR 2-5, range 1-49). No patients experienced delayed graft function as defined by the need for dialysis in the first week. Current evidence suggests that live donor kidney transport is safe and feasible.

Experience with 750 consecutive laparoscopic donor nephrectomies--is it time to use a standardized classification of complications?

PURPOSE: Laparoscopic living donor nephrectomy offers patients the benefits of decreased morbidity and improved cosmesis, while maintaining equivalent graft outcomes and complication rates similar to those of open donor surgery. With expressed concern for donor safety, using a standardized complication scale would allow combining data in a donor registry so potential donors could be adequately followed and counseled. We present the largest series to our knowledge of laparoscopic living donor nephrectomy by a single surgeon. MATERIALS AND METHODS: The institution's initial 750 laparoscopic living donor nephrectomies were included in the study, and a retrospective and prospective chart and database analysis was performed. RESULTS: Mean donor age was 40.5 years and average body mass index was 25.7 kg/m(2). There were 175 patients (23%) with 2 or more renal arteries while 161 (21.5%) had early arterial bifurcations. There were 3 open conversions (0.4%) and the overall complication rate was 5.46%. Median hospital stay was 1 day and the readmission rate was 1.2%. There were 5 reoperations (0.67%), none of which was for the control of bleeding. No patients required a blood transfusion and there were no mortalities. Using a modified Clavien classification of complications for living donor nephrectomy 65.8% were grade 1, 31.7% grade 2 (12.2% grade 2a, 14.6% grade 2b, 4.9% grade 2c) and 2.4% grade 3. There were no grade 4 complications. CONCLUSIONS: With appropriate patient selection and operative experience, laparoscopic living donor nephrectomy is a safe procedure associated with low morbidity. The use of a standardized complication system specific for this procedure is encouraged and could aid in counseling potential donors in the future.

Asynchronous, out-of-sequence, transcontinental chain kidney transplantation: a novel concept.

The organ donor shortage has been the most important hindrance in getting listed patients transplanted. Living kidney donors who are incompatible with their intended recipients are an untapped resource for expanding the donor pool through participation in transplant exchanges. Chain transplantation takes this concept further, with the potential to benefit even more recipients. We describe the first asynchronous, out of sequence transplant chain that was initiated by transcontinental shipment of an altruistic donor kidney 1 week after that recipient's incompatible donor had already donated his kidney to the next recipient in the chain. The altruistic donor kidney was transported from New York to Los Angeles and functioned immediately after transplantation. Our modified-sequence asynchronous transplant chain (MATCH) enabled eight recipients, at four different institutions, to benefit from the generosity of one altruistic donor and warrants further exploration as a promising step toward addressing the organ donor shortage.

Should pediatric patients wait for HLA-DR-matched renal transplants?

Graft survival rates from deceased donors aged 35 years or less among all primary pediatric kidney transplant recipients in the United States between 1996 and 2004 were retrospectively examined to determine the effect of HLA-DR mismatches on graft survival. Zero HLA-DR-mismatched kidneys had statistically comparable 5-year graft survival (71%), to 1-DR-mismatched kidneys (69%) and 2-DR-mismatched kidneys (71%). When compared to donors less than 35 years of age, the relative rate of allograft failure was 1.32 (p = 0.0326) for donor age greater than or equal to age 35. There was no statistical increase in the odds of developing a panel-reactive antibody (PRA) greater than 30% at the time of second waitlisting, based upon the degree of HLA-A, -B or -DR mismatch of the first transplant, nor was there a 'dose effect' when more HLA antigens were mismatched between the donor and recipient. Therefore, pediatric transplant programs should utilize the recently implemented Organ Procurement and Transplantation Network's (OPTN)allocation policy, which prioritizes pediatric recipients to receive kidneys from deceased donors less than 35 years of age, and should not turn down such kidney offers to wait for a better HLA-DR-matched kidney.

Effect of motor unit firing pattern on twitches obtained by spike-triggered averaging.

The spike-triggered averaging technique (STA) was used to determine the twitch profile of single motor units in human masseter during a voluntary isometric contraction. The effect of the immediate firing pattern of the unit on the twitch was assessed with a computer program which scanned the unit discharge records and selected valid trigger spikes for the averager on the basis of the interspike intervals preceding and following the trigger spike. Successive averages from the same data using different interval parameters revealed progressively more fusion of twitches as the instantaneous firing rate increased. When the data were averaged with interval parameters similar to those used in earlier studies, some fusion of the twitch profile was also evident. It is therefore likely that the degree of fusion of human motor unit twitches obtained by STA has been underestimated in the past. It is further concluded that masseter motor units are sufficiently fast-contracting to allow a relatively unfused twitch profile to be obtained with STA, provided trigger spikes are subjected to appropriate rate control.

Contribution of single motor units to the surface electromyogram.

McComas (1977) has published a method of estimating the number of motor units in human sketal muscle, based on peripheral nerve stimulation and recording of the surface electromyogram (EMG). One assumption of the method is that individual motor units, recruited by peripheral nerve stimulation just above threshold, give discrete observable increments to the surface EMG which are typical of motor units in the muscle. We have investigated this assumption in the thenar muscle. An EMG needle was inserted into the muscle and a series of individual motor units, activated voluntarily, was isolated. The discharge of these units was then used to trigger averaging of the concurrent surface EMG. Our results suggest that motor units activated by peripheral nerve stimulation close to threshold are not representative, in amplitude or timing, in their contribution to the surface EMG, of all motor units in the muscle.

Inferior colliculus. I. Comparison of response properties of neurons in central, pericentral, and external nuclei of adult cat.

The responses of 150 units in the central (ICC), pericentral (ICP), and external nuclei (ICX) of the inferior colliculus of the anesthetized cat were studied in relation to their tuning characteristics and binaural responses to tonal stimuli. Units in ICC were characterized by sharp tuning and binaural responses, while those in ICP and ICX were frequently very broadly tuned with a poorly defined best frequency. Nonetheless, in the latter nuclei a tendency existed for tonotopic organization to occur with high frequencies located externally and low frequencies at the margins of the central nucleus. Tuning measurements were hampered by the common occurrence of habituation in the discharges of single units in ICP and, to a lesser extend, ICX. The majority of units in ICP could be differentiated from those in ICX by their monaural input. Speculations were advanced linking anatomical cell types to physiological responses in the three nuclei and into the possible functional significance of the different behavior of units to tonal stimuli.

Renshaw cell activity in man.

The H-reflex elicited in triceps surae by percutaneous stimulation of the posterior tibial nerve was conditioned by stimuli applied through the same electrode. The differential sensitivity of motor and sensory fibres to duration of the stimulus pulse made it possible to condition the H-reflex with either a motor or a sensory stimulus. With both types of conditioning, the H-reflex was inhibited at conditioning-test intervals of 2-3 msec and was then facilitated, the peak of facilitation occurring at 5-8 msec with motor conditioning and 6-10 msec with sensory conditioning. The phase of facilitation was followed by further inhibition. We have concluded (1) that the effects of motor conditioning on the H-reflex result from the discharge of Renshaw cells activated by the antidromic volley in the motor axons, and (2) that the effects of sensory conditioning (at the times used in these experiments) are largely due to the activation of Renshaw cells secondary to the discharge of alpha motoneurones by the conditioning volley.

Differential sensitivity of motor and sensory fibres in human ulnar nerve.

The human ulnar nerve has been stimulated with square-wave pulses of various fixed durations. Measurements were made of the growth of hand myograms compared with elbow neurograms and of hand myograms compared with finger neurograms, for fixed durations of pulses and increasing strength. The effect of blocking sensory action potentials with stimuli of various durations has been investigated, as well as the blocking of action potentials in motor nerve fibres by voluntary activity. It is concluded that pulses of long duration (1 msec or more) selectively stimulate sensory fibres at threshold, whereas short duration pulses (less than 200 µsec) selectively stimulate motor fibres.