Associations of Postural Activities and Knowledge for Voice with Breathing Issues and Voice-Physical-Disorders Among Lyric Singers

OBJECTIVES/HYPOTHESIS

The purpose of this research was to study the associations of postural activities and knowledge of the voice of opera singers, recognized in the literature for the specificity of their posture. Additionally, the link between vocal pathologies and body pains on one hand, and posture control on the other hand was investigated.

METHODS

A questionnaire including 90 questions was distributed to singers in France and overseas during 6 months. Ninety-eight opera singers participated in the survey. Data were analyzed using Excel and Stata software.

RESULTS

The results showed that the singers who paid more attention to posture, postural work while singing, had knowledge of anatomy and postural role in singing voice, healthy lifestyle, and good body habits, had less vocal discomfort and pathologies, a better vocal preservation, and used more costo-abdominal breathing. On the other hand, knowledge of postural role and postural work was linked with pain and vocal fatigue. Furthermore, a preventive need was revealed concerning the providing of knowledge and skills to singers, but also to singing teachers, speech therapists, and stage workers.

CONCLUSION

Our study shows that benefits were found in the voice quality of opera singers with anatomical and postural knowledge and who work on posture as part of their vocal work compared to others. Postural work and knowledge increase attention to body pain and vocal fatigue. These results can inform health care providers, opera singers, and their teachers and performers of the benefits of posture on operatic voice quality. Accordingly, this study sparks new ideas for postural work and therapy in lyric voice.

Rehabilitation of Postural Control and Gait in Children with Cerebral Palsy: the Beneficial Effects of Trunk-Focused Postural Activities

PURPOSE

In children with cerebral palsy (CP), with impaired trunk control and toe-walking, trunk-focused rehabilitation (TFR) based on postural activities was hypothesized to improve trunk postural control, early trunk deceleration, and ankle dorsiflexion braking during walking. Methods: Seventeen children with CP (5-12 years) walking autonomously were randomly assigned to TFR and then usual rehabilitation (TFR-UR) or vice versa (UR-TFR).

RESULTS

Only after TFR was significant improvements in (i) the Trunk Control Measurement Scale score, postural sway on an unstable sitting device and standing, and (ii) early sternal and sacral decelerations and coupled negative ankle power due to plantar flexors.

CONCLUSION

TFR improves trunk dynamics and consequently improves coupled toe-walking.

Understanding and Managing Trauma-Induced Vestibular Deficits

Objectives:

Traumatic brain injury occurs frequently worldwide. Half of traumatic brain injuries are related to falls or motor vehicle accidents. The term “concussion” is often used to describe a minor form of traumatic brain injury. These often involve decelerative events to the head (e.g., flexion/extension injury) and can also cause damage to the vestibular system of the inner ear.

Materials and Methods:

The European Society for Clinical Evaluation of Balance Disorders meets yearly and has proposed an investigation and analysis of the vestibular consequences of traumatic brain injury. This review paper outlines these discussions.

Results:

The Society discussed all aspects of trauma-induced vestibular disorders along with diagnosis and management. They also assessed the diagnostic tests available to investigate these disorders.

Conclusion:

Trauma-induced vestibular disorders are difficult to manage, as our level of understanding of the pathology can be poor and anatomical localization can also be difficult. Accordingly, a definitive diagnosis cannot be pinpointed in many patients, but an extensive history taking is crucial to determine the nature and extent of vestibular involvement. Trauma can not only result in microtrauma to the central nervous system but can also significantly affect peripheral vestibular structures, particularly the otolith organs. The committee hopes that better understanding of trauma to the vestibular system, along with improvements in the field of radiology and vestibular assessments, will aid in more precise techniques of pinpointing pathology in order to develop an adapted treatment plan.

Impaired postural control of axial segments in children with cerebral palsy

BACKGROUND

Sensorimotor control of axial segments, which develops during childhood and is not mature until adolescence, is essential for the development of balance control during motor activities. Children with cerebral palsy (CP) have deficits in postural control when standing or walking, including less stabilization of the head and trunk which could affect postural control.

RESEARCH QUESTION

Is dynamic stabilization of axial segments during an unstable sitting task deficient in children with CP compared to typically developing children? Is this deficit correlated with the deficit of postural control during standing?

METHOD

Seventeen children with CP (GMFCS I-II) and 17 typically-developing children from 6 to 12 years old were rated on the Trunk Control Measurement Scale (TCMS). In addition, posturography was evaluated in participants while they maintained their balance in stable sitting, unstable sitting, and quiet standing, under "eyes open" and "eyes closed" conditions. In sitting tasks, the participants had to remain stable while being prevented from using the lower and upper limbs (i.e. to ensure the involvement of axial segments alone).

RESULTS

Children with CP compared to TD children had significantly larger surface area, mean velocity and RMS values of CoP displacements measured during the unstable sitting task and the standing task, under both "eyes open" and "eyes closed" conditions. No significant group effects were observed during the stable sitting task. The TCMS total score was significantly lower, indicating trunk postural deficit, in the CP group than in the TD group and was significantly correlated with postural variables in the sitting and standing tasks.

SIGNIFICANCE

Children with CP indeed have a specific impairment in the postural control of axial segments. Since the postural control of axial segments is important for standing and walking, its impairment should be taken into account in rehabilitation programs for children with CP.

Toe walking in children with cerebral palsy: a possible functional role for the plantar flexors

Equinus and toe walking are common locomotor disorders in children with cerebral palsy (CP) walking barefoot or with normal shoes. We hypothesized that, regardless of the type of footwear, the plantar flexors do not cause early equinus upon initial foot contact but decelerate ankle dorsiflexion during weight acceptance (WA). This latter action promoted by early flat-foot contact is hypothesized to be functional. Hence, we performed an instrumented gait analysis of 12 children with CP (Gross Motor Function Classification System class: I or II; mean age: 7.2 yr) and 11 age-matched typically developing children. The participants walked either barefoot, with unmodified footwear (4° positive-heel shoes), or with 10° negative-heel shoes (NHSs). In both groups, wearing NHSs was associated with greater ankle dorsiflexion upon initial foot contact, and greater tibialis anterior activity (but no difference in soleus activity) during the swing phase. However, the footwear condition did not influence the direction and amplitude of the first ankle movement during WA and the associated peak negative ankle power. Regardless of the footwear condition, the CP group displayed 1) early flattening of the foot and ample dorsiflexion (decelerated by the plantar flexors) during WA and 2) low tibialis anterior and soleus activities during the second half of the swing phase (contributing to passive equinus upon foot strike). In children with CP, the early action of plantar flexors (which typically decelerate the forward progression of the center of mass) may be a compensatory mechanism that contributes to the WA's role in controlling balance during gait.NEW & NOTEWORTHY Adaptation to walking in negative-heel shoes was similar in typically developing children and children with cerebral palsy: it featured ankle dorsiflexion upon initial contact, even though (in the latter group) the soleus was always spastic in a clinical examination. Hence, in children with cerebral palsy, the early deceleration of ankle dorsiflexion by the plantar flexors (promoted by early flattening of the foot, and regardless of the type of footwear) may have a functional role.

How do children aged 6 to 11 stabilize themselves on an unstable sitting device? The progressive development of axial segment control

Postural control continues to develop during middle childhood as shown by the decrease in body sway in stance between the ages of 5 and 11. Although head and trunk control is crucial for balance control during both static and dynamic activities, evaluating its specific development and its contribution to overall postural control is methodologically challenging. Here, we used an unstable sitting device adapted to ensure that only the axial segments could control the balance of the device and thus the balance of the upper body. This study aimed to assess the development of the postural stabilization of axial body segments during middle childhood. Thirty-six children (in three age groups: 6-7yo, 8-9yo, and 10-11yo) and 11 adults sat on the unstable sitting device and had to stabilize their axial segments under several conditions: a moderate vs. high level of balance challenge, and eyes open vs. eyes closed. Upper-body postural sway (area, mean velocity and root mean square (RMS) of the center of pressure (CoP) displacement) decreased progressively with age (6-7yo > 8-9yo > 10-11yo > adults), and this effect was accentuated when the balance challenge was high (for CoP area) or in the "eyes closed" condition (for CoP area and RMS). The stabilization strategies were assessed by anchoring indexes computed from three-dimensional kinematics. A progressive shift was showed, from an "en bloc" pattern at 6-7 years of age toward a more articulated (i.e. adult-like) pattern at 10-11. A head-on-space stabilization strategy first emerged at the age of 8-9. Middle childhood is an important period for the development of axial segment stabilization, which continues to mature until adulthood. This development might be related to the introduction and progressive mastery of feedforward sensorimotor processes and might contribute strongly to the development of overall postural control.

Gait post-stroke: Pathophysiology and rehabilitation strategies

We reviewed neural control and biomechanical description of gait in both non-disabled and post-stroke subjects. In addition, we reviewed most of the gait rehabilitation strategies currently in use or in development and observed their principles in relation to recent pathophysiology of post-stroke gait. In both non-disabled and post-stroke subjects, motor control is organized on a task-oriented basis using a common set of a few muscle modules to simultaneously achieve body support, balance control, and forward progression during gait. Hemiparesis following stroke is due to disruption of descending neural pathways, usually with no direct lesion of the brainstem and cerebellar structures involved in motor automatic processes. Post-stroke, improvements of motor activities including standing and locomotion are variable but are typically characterized by a common postural behaviour which involves the unaffected side more for body support and balance control, likely in response to initial muscle weakness of the affected side. Various rehabilitation strategies are regularly used or in development, targeting muscle activity, postural and gait tasks, using more or less high-technology equipment. Reduced walking speed often improves with time and with various rehabilitation strategies, but asymmetric postural behaviour during standing and walking is often reinforced, maintained, or only transitorily decreased. This asymmetric compensatory postural behaviour appears to be robust, driven by support and balance tasks maintaining the predominant use of the unaffected side over the initially impaired affected side. Based on these elements, stroke rehabilitation including affected muscle strengthening and often stretching would first need to correct the postural asymmetric pattern by exploiting postural automatic processes in various particular motor tasks secondarily beneficial to gait.

Knee kinetic pattern during gait and anterior knee pain before and after rehabilitation in patients with patellofemoral pain syndrome

Patellofemoral pain is likely due to compressive force acting on the patella related in turn to knee extension moment. The latter variable was assumed to be (i) reduced during short-distance free walking in case of patellofemoral pain syndrome and (ii) increased after therapeutic pain reduction. Peak knee extension moment at beginning of stance phase was recorded by three-dimensional gait analysis in 22 controls and in 23 patients with patellofemoral pain syndrome before and after rehabilitation of knee extensors and flexors to reduce the pain. Pain would occur mainly in stressful activities such as stair negotiation or squatting and was quantified by the anterior knee pain scale. Peak knee extension moment was significantly reduced in all the patients before treatment (n=23) compared to controls, although no one had pain during free walking. In the 17 patients who experienced significant post-rehabilitation pain reduction in their stressful activities, the peak knee extension moment was significantly reduced before treatment compared to controls and significantly increased after treatment, reaching values similar to control values. The peak knee extension moment during free walking appears to be a good kinetic variable related to a compensatory mechanism limiting or avoiding anterior knee pain and may be of interest in assessing knee dynamics alteration in patients with PFPS.

Compensatory mechanism involving the knee joint of the intact limb during gait in unilateral below-knee amputees

This study evaluated the asymmetry of knee kinetics during uncomfortable gait induced by prosthesis misalignment to further demonstrate the compensatory function of the knee joint of the intact limb during gait. Three-dimensional gait analysis including knee kinematics and kinetics at the beginning of stance phase was conducted in 15 healthy subjects and 17 unilateral trans-tibial amputees (TTA) walking at self-selected speed in three conditions of prosthetic alignment: initial alignment (IA); initial alignment altered either by 6 degrees of internal rotation (IR) or by 6 degrees of external rotation (ER) applied on the pylon. Patients reported best comfort of gait in IA condition and discomfort mainly in IR condition. Maximum knee flexion and knee total work at power phases K0-K2 were significantly higher in intact limbs compared to prosthetic and control limbs. In intact limbs, these variables had significantly higher values (+10-35%, p<0.05) in IR condition than IA condition whereas these were not altered across conditions in prosthetic limbs. In trans-tibial amputees, inducing uncomfortable gait by internally rotating the prosthetic foot did not alter the knee kinetics of the prosthetic limb, which suggests a protective mechanism. Knee kinetics of the intact limb did alter, which suggests a compensatory mechanism.

Évaluation des capacités et des performances: contribution des monitorages de la locomotion en situation d'exercice et de vie réelle

OBJECTIVES

To determine the value of ambulatory monitoring in assessing human gait. To describe the sensors, the parameters and the ambulatory devices.

MATERIALS AND METHODS

Literature review and practical experience about techniques, principles, objectives and limits.

RESULTS

Accelerometry is the main technique for ambulatory monitoring because of its reliability, pertinence of signals and software developed for interpretation. Simultaneous monitoring of heart rate response is clinically relevant. Pedometers and actimeters can answer precise clinical questions about amount of walking activity.

CONCLUSION

Ambulatory monitoring during long periods (one day or more) is important, especially for rehabilitation medicine because it measures the actual patient activity performed and participation. The simultaneous monitoring of environmental conditions of activity should improve the interpretation of the data collected.

Influence of terrain on metabolic and temporal gait characteristics of unilateral transtibial amputees

The difficulties confronted by amputees during overground walking are rarely investigated. In this study, we evaluated, in real-world situations, the influence of ground surface on walking in young, active amputees by measuring temporal and spatial gait parameters (free walking speed [FWS], step length [SL], step rate), energy expenditure (EE) (e.g., oxygen uptake, oxygen cost [O(2)C]), and Rating of Perceived Exertion (RPE). Ten active transtibial amputees and ten nondisabled control subjects walked at self-selected speeds on three types of ground surface (asphalt, mown lawn, and high grass). No significant differences were observed between the two groups on asphalt and mown lawn. Differences between nondisabled subjects and amputees occurred for FWS (p = 0.03) and O(2)C (p = 0.04) on asphalt and mown lawn and for all variables in high grass. When amputees (even though very active) were exposed to a particularly difficult environment, their FWS decreased (p = 0.008) and their EE and RPE increased (p = 0.005) compared with nondisabled subjects. In high grass, both groups reduced their self-selected speeds (-15% for control subjects and -16% for amputees). Control subjects reduced their velocity by reducing both SL (-8.7%) and cadence (-7.1%), whereas amputees reduced their velocity by reducing SL (-17%) only.

Increasing shoe instep improves gait dynamics in patients with a tibiotalar arthrodesis

Degenerative osteoarthritis in subtalar and midtarsal joints occurring after tibiotalar arthrodesis may be related to biomechanical factors. For patients with tibiotalar arthrodesis walking with their everyday shoes, the ground reaction force is posterior at heel-off and the maximal foot-tibia dorsiflexion is at its upper limit. We hypothesized that increasing the instep of the shoes would improve these abnormalities. Three-dimensional gait analysis was done in nine patients with ankle arthrodesis fused in the neutral position and for 10 control subjects. Four conditions of walking were tested: barefoot, wearing everyday shoes, wearing everyday shoes with the instep increased by 1 cm, and wearing everyday shoes with the instep increased by 2 cm. In the arthrodesis group, the two modified delayed heel-off shoe conditions shifted the ground reaction force closer to the metatarsal heads at heel-off to a normal range, and reduced the maximal foot and tibia dorsiflexion angle. Based on these results, patients with a tibiotalar arthrodesis in the neutral sagittal position may be advised to choose shoes with an instep of approximately 25 mm.

The effect of tibio-talar arthrodesis on foot kinematics and ground reaction force progression during walking

Degenerative osteoarthritis in the subtalar and mid-tarsal joints occurring after tibio-talar arthrodesis is thought to be a consequence of abnormal foot dynamics. We hypothesized that the forward tilt of the tibia during stance induces early heel-off and alteration of the progression of ground reaction force (GRF) after ankle arthrodesis. Three-dimensional gait analysis was performed on nine patients who had an ankle arthrodesis fused in a neutral position and on ten control subjects. Patients walking barefoot were compared to controls. The GRF progression was shifted forward during mid-stance, heel-off occurred earlier and was associated with less anterior tilt of the tibia and a more posterior position of the GRF with reference to the metatarsal heads. The GRF progression, heel-off and tibial tilt were not significantly different between patients and controls when walking in shoes but the GRF was still more posterior at heel-off. Increasing the walking speed worsened the anomalies of foot dynamics. These alterations of foot dynamics are thought to be associated with pathogenic stresses applied to the mid-foot.

[Clinical and three-dimensional kinematic features of the upper limb after replantation of the hand]

INTRODUCTION

Functional assessments of hand replantation after traumatic amputation are considered as good although frequent deficits of long fingers mobility and hand sensitiveness occur.

AIMS

To evaluate the capability of handling and the compensatory mechanisms involved in handling.

METHODS

Prospective study in eight right-handed males who had distal amputation of the left upper limb with hand replantation for more than two years. Eight males with paired age and handedness served as control. Skin sensitiveness (thread test), mobility (TAM), functional capability (Box and Blocks test, 400 points test) and occupational outcome were assessed. Three-dimensional analysis (opto-electronic device) of the motion of the trunk and the upper limbs (arm, forearm, hand) was made during a pointing and gripping-shifting maneuver and the time of the related phases was measured (dynamometric cube device). Correlation between clinical assessments and three-dimensional analysis were tested.

RESULTS

Patients with replantation had a remarkable recovery of the absolute and relative times of the various phases of the handling maneuver. Only the gripping phase was significantly prolonged in patients, this result was correlated with the deficit in motor function and sensitiveness of the replanted hand. The visual control was higher because of the lack of superficial and deep sensitiveness. Compensatory mechanisms involved a lateral shift of the replanted limb segments, probably attributed to the lateral shift of the trunk.

CONCLUSION

Patient with a replanted hand develops a homogenesis displacement of the trunk and the pectoral girdle to compensate the shortening and the reduction in active mobility of the hand. This compensatory mechanism, observed in a small scale in healthy too, is efficient with respect to the handling phases.

The effect of inturning of the foot on knee kinematics and kinetics in children with treated idiopathic clubfoot

OBJECTIVE

To assess the effect of internal foot progression angle (inturning) on knee dynamics in children with treated clubfeet.

DESIGN

Prospective study dividing a population of clubfeet according to the factor inturning.

BACKGROUND

Excessive internal or external foot progression angle increases knee flexion by a backward shift of the ground reaction force to the knee joint in children with cerebral palsy. Similarly, inturning in clubfeet was hypothesized to shift the ground reaction force backwards with reference to the knee joint, increasing the external knee flexion moment and the maximal knee flexion at stance.

METHODS

Three-dimensional gait analysis was performed on 20 children with surgically treated clubfeet (n=28) to assess alterations of knee dynamics related to inturning (>7 degrees ) and on 13 normal children.

RESULTS

Inturning occurred in 46% of the clubfeet and was associated during stance, at maximal knee flexion, to an increase in maximal knee flexion (+7 degrees ), external knee flexion moment (+60%) and related lever arm to the knee (+100%) and at minimal knee flexion, to a reduction in external knee extension moment (-62%) and related lever arm (-58%). Inturning was associated with a more frequent prolongation of internal knee extension moment and of rectus femoris activity exceeding 50% of stance.

CONCLUSION

Inturning in clubfeet is associated with knee dynamics alteration, which might contribute to the long-term development of knee osteoarthritis.

RELEVANCE

The therapeutic correction of inturning in clubfeet would be of importance if the consecutive knee dynamics alteration is shown by further studies to contribute to long-term degenerative knee pathology.

Effect on balance and gait secondary to removal of the second toe for digital reconstruction: 5-year follow-up

Foot anatomy and lower limb function were analyzed in 11 children (aged 6.5-12.5 y) 5 years after removal of one or two second toes for digital reconstruction. In addition to physical examination and x-rays, postural balance and three-dimensional measurements of gait were analyzed. Among the 15 operated feet, five had bridle scars, three had claw deformities of the third toe, five had pain in the first intermetatarsal space, and seven had overt or early-stage hallux valgus (including five after unilateral toe removal). Hallux valgus deformation was also observed in three nonoperated feet. Maintenance of balance and rate of displacement of the center of pressure when standing on one foot with eyes closed were significantly altered for operated limbs compared with nonoperated limbs. Gait was rapid because of increased step cadence. Foot progression angle and ankle and knee joint sagittal kinematics during walking were normal. Although children appeared to not be affected in their daily life by the removal of the second toe(s), related foot anatomic and functional modifications require further follow-up.

[Georges Gilles of Tourette, pioneer of gait analysis in the nervous system diseases]

Georges Gilles de la Tourette's contribution to neurology goes beyond the description of the neurological disorder named after him. On December 28, 1885, he defended his doctoral thesis devoted to "gait in the diseases of the nervous system, studied by the method of imprints". In collaboration with Albert Londe, he worked for two years in Charcot's department on "a simple method applicable to both healthy and unhealthy patients", establishing the scientific and modern basis of functional exploration of human gait. The purpose was to "record the modifications of the gait and to fix them permanently, using suitable devises to guarantee not only rigorous comparison, but also to prevent observers, making use of the same method, from disputing or canceling the results completely independent of the experimenter himself". Georges Gilles de la Tourette defined the various characteristic parameters and provided the normal reference values in males and females, determining the physiological asymmetry of steps. He described spastic gait, shaking palsy, and locomotor ataxia. He distinguished between disorders of nervous control and related joint diseases. He also classified gait disorders occurring during hemiplegia. Modern development of kinetic, kinematic and biomechanical studies is a good illustration of the current relevancy of Gilles de la Tourette's contribution.

Respiratory oscillation mechanics in infants with bronchiolitis during mechanical ventilation

The aim of the study was to describe the pattern of respiratory oscillation mechanics and responses to positive end-expiratory pressure (PEEP) in bronchiolitis. Six infants were studied during the course of mechanical ventilation. A 20 Hz sinusoidal pressure variation was applied at the endotracheal tube where flow was measured with a pneumotachograph. Resistance and reactance obtained from the complex pressure-flow ratio were separated during inspiration (R(rs,i); X(rs,i)) and expiration (R(rs,e); X(rs,e)), and the differences between R(rs,i) and R(rs,e) (deltaR(rs)) and X(rs,i) and X(rs,e) (deltaX(rs)) were calculated. The data were corrected for the mechanical characteristics of the endotracheal tube. The measurements were repeated while PEEP was varied between 0 and 8 hPa. Two infants were found to have normal R(rs) and near-zero X(rs) and both parameters exhibited little change within the respiratory cycle or with varying PEEP. Four infants had high R(rs) at zero PEEP. In two, R(rs,i) was markedly elevated (108.5 and 85.2 hPa.s/L, respectively), and X(rs,i) was markedly negative (-25.0 and -22.5 hPa.s/L, respectively) at zero PEEP, while deltaR(rs) and deltaX(rs) were small. R(rs,i) and the absolute value of X(rs,i) decreased with increasing PEEP. This pattern of oscillation mechanics was consistent with low lung volumes and atelectasis, being reversed by increasing PEEP. In the remaining two subjects, R(rs,i) was moderately elevated (57.8 and 53.6 hPa.s/L, respectively) and X(rs,i) moderately negative (-12.5 and -7.7 hPa.s/L, respectively) at zero PEEP. DeltaR(rs) (-59.8 and -56.5 hPa.s/L, respectively) and delta(rs) (28.1 and 48.7 hPa.s/L, respectively) were large, but were dramatically reduced by increasing PEEP. These patterns were consistent with expiratory airflow limitation. Measurements of respiratory impedance are, therefore, informative in regard to the pathophysiological mechanisms occurring in bronchiolitis during mechanical ventilation, and they may be helpful in setting the level and assessing the effect of PEEP.

Laryngeal reflex apnea is blunted during and after hindlimb muscle contraction in sheep

This study was carried out on seven chloralose-anesthetized sheep and was designed to investigate the role of muscular afferent fiber stimulation on the duration of reflex apnea triggered by laryngeal stimulation (LS). In six animals, injection of distilled water onto the laryngeal mucosa provoked a 15.7 +/- 1.0 s (mean +/- SE) apnea associated with a rise in systemic blood pressure (+7 +/- 0.8 Torr). Electrically induced contractions (EIC) of the hindlimb muscles doubled the metabolic rate and ventilation and reduced the duration of the apnea produced by LS to 7.4 +/- 1.0 s (P < 0.01). Apnea duration was still reduced during the first minute after the cessation of EIC (7.2 +/- 1.1 s, P < 0.01) but returned to control after a 5-min recovery period (16.7 +/- 1.6 s). The apnea triggered by LS was also reduced during EIC when the venous return was impeded by occluding the inferior vena cava (5.2 +/- 1.1 s, P < 0.01), despite a profound hypocapnia (20.7 +/- 0.3 Torr). The duration of apnea was not significantly affected (14.2 +/- 1.4 s) by breathing a 6% CO2-14% O2 in N2 gas mixture that roughly mimicked the alveolar gas composition when the apnea turned off. These results suggest that chemical drive has a negligible role in the fast reinitiation of breathing after LS during muscular stimulation. Stimulation of muscle afferent fibers does, however, appear to be a potent source of ventilatory reflexes capable of counteracting the inhibition of breathing resulting from laryngeal stimulation. Conversely, it is postulated that any reduction in somatic afferent traffic during this type of reflex apnea, including that resulting from the LS-induced systemic vasoconstriction, may delay the termination of apnea.

Respiratory system reactance as an indicator of the intrathoracic airway response to methacholine in children

The upper airways may contribute to increases in airway resistance in response to a bronchial challenge, and thus decrease the specificity of such challenge tests to diagnose airway hyperresponsiveness when forced oscillation techniques are used to evaluate changes in respiratory system resistance (Rrs). A concomitent decrease in respiratory system reactance (Xrs) may indicate a change in the intrathoracic airways and/or lung parenchyma, provided that extrathoracic airway wall motion is prevented. To test the value of Xrs in the evaluation of bronchial hyperresponsiveness, we studied the respiratory impedance response to methacholine in 38 children with a history of asthma (aged 6-14.5 years), and compared the results to changes in the forced expiratory volume in one second (FEV1). Rrs and Xrs were measured by the forced oscillation technique with pseudorandom (11 subjects) or sinusoidal (27 subjects) pressure variations applied around the child's head to minimize upper airway wall motion. Changes in Rrs and in Xrs at 12 Hz (Rrs12, Xrs 12) correlated significantly with changes in FEV1 (P < 0.005). A decrease in FEV1 > or = 20% was observed in 23 subjects. When these 23 subjects were compared with the 15 children who did not show significant changes in FEV1, the responding group had larger mean +/- SEM changes in Rrs (116.0 +/- 13.2% vs 60.4 +/- 11.4%, P < 0.006) and in Xrs (-2.1 +/- 0.4 hPa.s/L vs -0.9 +/- 0.3 hPa.s/L, P < 0.03) than the nonresponders. The receiver operating characteristics (ROC) curve analysis was used to assess the diagnostic value, i.e., specificity and sensitivity, of different levels of change in Rrs and Xrs, with reference to FEV1. The overall incidence of false results was similar for Rrs and Xrs. The optimum diagnostic value for Rrs was a 70% increase, which corresponded to a sensitivity of 87% and a specificity of 67%. For Xrs the optimum decision level was -1 hPa.s/L, corresponding to a sensitivity of 70% and a specificity of 80%. It is concluded that Xrs may improve the specificity of the forced oscillation technique in interpreting the airway response to methacholine. This may be of particular interest in young children unable to perform forced expirations.

Improved recovery from laryngeal-stimulation-induced apnea by alpha-adrenergic blockade in adult rabbits

The apnea triggered by laryngeal stimulation (LS) is associated with a redistribution of blood flow towards the heart and the brain that depends upon peripheral vasoconstriction. The circulatory component of the response to LS has been shown to be reduced following injection of large dose of beta-adrenergic agonist that more intriguingly blunted the ventilatory response as well. To test whether the reduction of LS-induced apnea could be related to the decreased magnitude of the peripheral vasoconstruction, the effects of the alpha-adrenergic antagonist urapidil on the ventilatory and blood pressure responses to LS were studied in 6 adult rabbits. alpha-Adrenergic blockade reduced both the rise in blood pressure and the magnitude of hypopnea induced by LS. These results suggest that the circulatory component of the laryngeal chemoreflex, i.e. the peripheral vasoconstruction, contributes to the magnitude of the ventilatory depression.

[Modality and causes of 259 deaths in a pediatric intensive care unit]

BACKGROUND

There are few data available from European pediatric intensive care units (PICU) regarding the modes of death and their causes.

POPULATION AND METHODS

Two hundred and fifty nine children, not including neonates, died in the PICU over a 7-year period (1987-1993). Data were obtained from a computerized data base and the retrospective review of medical records by two intensivists. Deaths were classified into three groups according to the terminal event: brain death (BD), unsuccessful resuscitation (UR), do-not-resuscitate order and limitation and/or withdrawal of therapy (LWT).

RESULTS

BD was the most common mode of death (38%); UR accounted for 34% and LWT for 28% of deaths. There was no significant annual variation in the proportion of BD, UR and LWT. Age and sex were similar in the three groups. The predominant organ system failure involved upon admission was the central nervous system (52%) in the LWT group, and the cardiovascular system (54%) in the UR group. Severe chronic disease (37%) and immunosuppression (19%) were more prevalent in the LWT group than in the BD group. Time from admission to death was longer in the LWT group (median = 119 hours) as compared to the UR group (10 hours) and the BD group (54 hours). Ten percent of the BD patients became organ transplant donors. Sixty-seven per cent of BD patients had medical contraindication for organ donation: parents did not accept organ donation in 61% of potential cases. Thirty deaths (12%) seemed to be avoidable; dehydration from acute infectious gastroenteritis (n = 7) was the most common cause of avoidable death.

CONCLUSIONS

The modes of death in our PICU were statistically not different from those seen in two of four North-American PICUs; LWT was less prevalent than in the two other PICUs, but the patient populations were very different (presence of neonates and many cardiovascular surgery patients). Assessment of the severity of illness at admission and of functional outcome in the survivors are mandatory in future studies.

Gastroesophageal reflux and acute life-threatening episodes: role of a central respiratory depression

The aim of this study was to evaluate plasma levels of beta-endorphins in babies with gastroesophageal reflux (GOR) admitted for acute life-threatening episodes (ALTE). In case of ALTE (n = 15), beta-endorphin levels were significantly increased compared to sudden infant deaths syndrome siblings with GOR of a similar gravity evaluated for risk factors (n = 13). beta-Endorphin levels are decreased following successful treatment of GOR. Studies of ventilation suggest that changes in the central respiratory drive are associated with a reduction in plasma beta-endorphin levels.

Cytology: a simple, rapid, sensitive method in the diagnosis of Helicobacter pylori

Cytology and the rapid urease test on gastric biopsies may diagnose Helicobacter pylori (H. pylori) infection within an hour. We evaluated the sensitivity and reproducibility of touch cytology (imprints from biopsies). In 19 patients with duodenal ulcer, biopsies were obtained from the antrum, fundus, and bulb. H. pylori was diagnosed in 42 sites on smears: 28 by culture and 23 by histology. H. pylori was present in the antrum and fundus in 16 and in the bulb in 11. Assessment of paired antral biopsies in 29 additional patients with or without touch cytology (imprints) before specimens were sent for histology or culture revealed no difference for the presence of H. pylori. A second reading of the 58 smears by a second observer revealed agreement on the presence or absence of H. pylori in 53 (91%). In conclusion, touch cytology is a simple rapid, sensitive, and reproducible diagnostic method for H. pylori that does not alter the quality of biopsies for subsequent culture or histologic examination. For the first time, diagnostic methods have been compared on the same biopsies, eliminating sampling variation.

Touch cytology, a useful diagnostic method for diagnosis of upper gastrointestinal tract infections

Candida albicans, Campylobacter pylori, and Giardia lamblia are microorganisms that are frequently found in the upper gastrointestinal tract. A cytological smear of biopsies obtained at endoscopy was compared with the pathologic examination of biopsies. Candida albicans was found in 55 patients, Campylobacter pylori in 54, Giardia lamblia in 31; cytology was positive in 43, 46, and 22 cases, respectively, and biopsy in 29, 43, and 22 cases. Cytology was thus the only positive test in 26 cases with Candida albicans (47% of the 55 cases), in 11 cases of Campylobacter pylori (20%), and in nine cases of Giardia lamblia (29%). We believe that the cytological smear of biopsies (touch cytology) is a quick and sensitive method for diagnosing infections of the upper gastrointestinal tract, increasing the diagnostic yield obtained by biopsy alone.

[Evaluation of per-endoscopic cytology in the identification of Campylobacter pylori on gastric mucosa]

The presence of Campylobacter pylori on gastric mucosa was evaluated by touch cytology of gastric biopsies in a series of 100 patients. Results were compared to biopsy cultures. Of 43 culture-positive patients, cytology was positive in 37 (86 p. 100). Cytology was positive in 16 of 57 culture-negative patients, who had peptic ulcer and/or gastritis on biopsy, conditions widely associated with the presence of Campylobacter pylori. Cytologic examination, yielding quick results, is thus a sensitive diagnostic method for Campylobacter pylori. In addition, retrospective studies of previous specimens are possible: among 11 patients with a follow up of more than one year, three of the four Campylobacter pylori carriers subsequently developed an ulcer.