Organ donation by Maastricht-III pediatric patients: Recommendations of the Groupe Francophone de Réanimation et Urgences Pédiatriques (GFRUP) and Association des Anesthésistes Réanimateurs Pédiatriques d'Expression Française (ADARPEF). Part II: Specific organizational and technical considerations.

A panel of pediatric experts met to develop recommendations on the technical requirements specific to pediatric controlled donation after planned withdrawal of life-sustaining therapies (Maastricht category III). The panel recommends following the withdrawal of life-sustaining therapies protocol usually applied in each unit, which may or may not include immediate extubation. The organ retrieval process should be halted if death does not occur within 3 h of life-support discontinuation. Circulatory arrest is defined as loss of pulsatile arterial pressure and should be followed by a 5-min no-touch observation period. Death is declared based on a list of clinical criteria assessed by two senior physicians. The no-flow time should be no longer than 30, 45, and 90 min for the liver, kidneys, and lungs, respectively. At present, the panel does not recommend pediatric heart donation after death by circulatory arrest. The mean arterial pressure cutoff that defines the start of the functional warm ischemia (FWI) phase is 45 mmHg in patients older than 5 years and/or weighing more than 20 kg. The panel recommends normothermic regional perfusion in these patients. The FWI phase should not exceed 30 and 45 min for retrieving the pancreas and liver, respectively. There is no time limit to the FWI phase for the lungs and kidneys. The panel recommends routine sharing of experience with Maastricht-III donation among all healthcare institutions involved in order to ensure optimal outcome assessment and continuous discussion on the potential difficulties, notably those related to the management of normothermic regional perfusion in small children.

Organ donation by Maastricht-III pediatric patients: Recommendations of the Groupe Francophone de Réanimation et Urgences Pédiatriques (GFRUP) and Association des Anesthésistes Réanimateurs Pédiatriques d'Expression Française (ADARPEF) Part I: Ethical considerations and family care.

The French Transplant Health Authority (Agence de la Biomédecine) has broadened its organ- and tissue-donation criteria to include pediatric patients whose death is defined by circulatory criteria and after the planned withdrawal of life-sustaining therapies (WLST) (Maastricht category III). A panel of pediatric experts convened to translate data in the international literature into recommendations for organ and tissue donation in this patient subgroup. The panel estimated that, among children aged 5 years or over with severe irreversible neurological injury (due to primary neurological injury or post-anoxic brain injury) and no progression to brain death, the number of potential donors, although small, deserves attention. The experts emphasized the importance of adhering strictly to the collegial procedure for deciding to withdraw life support. Once this decision is made, the available data should be used to evaluate whether the patient might be a potential donor, before suggesting organ donation to the parents. This suggestion should be reserved for parents who have unequivocally manifested their acceptance of WLST. The discussion with the parents should include both the pediatric intensive care unit (PICU) team under the responsibility of a senior physician and the hospital organ- and tissue-procurement team. All recommendations about family care during the end of life of a child in the PICU must be followed. The course and potential challenges of organ donation in Maastricht-III pediatric patients must be anticipated. The panel of experts recommended strict compliance with French recommendations (by the Groupe Francophone de Réanimation et Urgences Pédiatriques) about WLST and providing deep and continuous sedation until circulatory arrest. The experts identified the PICU as the best place to implement life-support discontinuation and emphasized the importance of returning the body to the PICU after organ donation. French law prohibits the transfer of these patients from one hospital to another. A description of the expert-panel recommendations regarding the organization and techniques appropriate for children who die after controlled circulatory arrest (Maastricht III) is published simultaneously in the current issue of this journal..

Long-term dysfunctions of neural stereoscopic mechanisms after unilateral extraocular muscle proprioceptive deafferentation.

1. Neural correlates of the permanent deficits in depth perception that occur when extraocular muscle proprioceptive (EMP) afferents are interrupted unilaterally in kittens were investigated by performing extracellular recordings in the primary visual cortex (area 17) in adulthood. Unilateral section of the ophthalmic branch of the trigeminal nerve (V1 nerve) were performed in 11 cats when they were between 5 and 12 weeks of age (uni-V1 group). Electrophysiological results were compared with those obtained in 17 normal adult cats (control group). 2. Binocular interactions were assessed by testing the sensitivity of cortical neurons to dichoptic presentations of moving sine-wave gratings whose interocular positional phase relationship was randomly varied. The amplitude modulation between the minimum and the maximum binocular responses defined the dynamic range. The degree of binocular suppression or facilitation was assessed by comparing these binocular response limits with the optimal monocular responses evoked through either eye at the best spatial frequency. The variability of both monocular and binocular responses was estimated by using the variation coefficient. 3. In uni-V1 cats, both the dynamic range and the degree of binocular suppression were significantly less pronounced than in controls, whereas binocular facilitation was not affected. The variability of the binocular responses was significantly increased, unlike monocular responses, whose variability was similar to control values. 4. From Fourier analysis of the poststimulus time histograms, two clear-cut categories of cells emerged that were differentially affected in the uni-V1 group. The "modulated" cells showed significantly less binocular suppression than in controls, and the "unmodulated" cells had binocular responses that were significantly more variable than in controls. Results from "simple" cells were similar to those of modulated cells, and results from "complex" cells were similar to those of unmodulated cells. However, in the unmodulated population, which was composed of both simple and complex cells, it was shown that the increase of variability was due to that of complex cells. 5. A nonparametric statistical test was applied on the interocular phase shift tuning curves to determine the minimum stimulus change necessary to elicit a significant change in the neural response. Two categories of cells were determined: the "discriminative" cells (80% in controls but 45% in uni-V1 cats) combined pronounced binocular suppression and dynamic range with relatively low variability. The reverse was true in the case of "nondiscriminative" cells (20% in controls and 55% in uni-V1 cats). 6. In uni-V1 cats, about half of the cells were monocularly activated.(ABSTRACT TRUNCATED AT 400 WORDS)

[Cortical modulations of the fine temporal structures of impulse trains in the dorsal lateral geniculate body in cats]. / Modulations corticales de la structure temporelle fine des trains d'impulsions dans le corps genouillé latéral dorsal du Chat.

In response to a visual stimulation, "replicated triplets" of impulses may appear in many spike trains recorded from the cat dorsal lateral geniculate nucleus (dLGN). The number and the temporal structure of these triplets depend upon the general organization of the geniculate impulse trains. In this study, we show that a pharmacological blockade of the corticothalamic activity, obtained through microinjection of GABA into area 17, affects the replicated triplet production and leads to an increase in the dispersal of their structure. These results suggest that the corticothalamic pathway closely influences the fine temporal organization of the geniculate messages.

Temporal limits of the susceptibility of depth perception to proprioceptive deafferentations of extraocular muscles.

In a previous study, extraocular muscle proprioception (E.O.M.P.) was shown to play an important role in the postnatal development of depth perception: following unilateral or bilateral sections of the ophthalmic branch of the trigeminal nerve (V1th nerve) performed at 6-8 weeks of age, the binocular thresholds were 2 to 3 times higher than in control animals. Since the V1-sections produced no deficits when performed in adults, the temporal limits of a period of susceptibility remained to be determined. In order to assess the lower and upper limits of the period during which these perceptual deficits could be induced, unilateral or bilateral V1-sections were performed in kittens at different ages. Depth perception thresholds were measured by using the jumping stand technique. Sections of the V1 nerve only produced significant impairments of the binocular depth thresholds when performed after 3 weeks of age. They could be observed when unilateral sections were performed at up to 13 weeks of age and with bilateral sections at up to 10 weeks of age. These functional impairments appeared to remain permanently through adult life.

Neuronal stereoscopic processing following extraocular proprioception deafferentation.

In adult cats, after section of extraocular muscle proprioceptive (EOMP) afferents during the 'critical period', most cortical area 17 cells loose their ability to discriminate changes in binocular spatial disparity. After unilateral section this loss depends on whether or not cortical cells modulate their responses to the presentation of sinusoidal gratings linearly. For 'modulated cells', this loss is due to a reduction of binocular suppression while for 'unmodulated cells', it is due to a selective increase in the variability of the binocular response. These permanent neural dysfunctions show that balance in EOMP inflow plays a crucial role in cortical processing of binocular depth discrimination.

Incidence of diverticulitis.

The hospital admission rates for symptomatic colonic diverticulitis (International Code No. 572.1) in the populations served by the main teaching hospitals in Fiji, Singapore, Nigeria and North East Scotland have been estimated. In non-Europeans the condition is very rare occurring in about only one person in a million per year. It is some forty times commoner in Europeans living in the Tropics, and about eighty times more common in Scotland. It is considered that the difference is due principally to the greater age and low-residue diet of the European populations.