Predicting the recovery of ventilatory activity in central respiratory paralysis.

OBJECTIVE: To assess the value of the diaphragmatic response to transcranial magnetic stimulation (TMS) in predicting the recovery of ventilatory activity after CNS lesions responsible for central respiratory paralysis. METHODS: The authors studied 11 long-term ventilator-dependent patients with central respiratory paralysis (description group: spinal trauma 10, medullary ischemia 1) and 16 patients with central respiratory paralysis for less than 10 weeks (prognostic group, evaluated after a 1-year follow-up: spinal trauma 8, medullary ischemia 4, radiation myelitis 1, subdural hematoma 1, complication of neurosurgery 2). RESULTS: In the description group, all the patients had a bilaterally abolished diaphragm response. In the prognostic group, six patients were fully ventilator dependent because of a complete absence of ventilatory activity at follow-up time. They lacked any diaphragm response. The 10 other patients had recovered ventilatory activity and full (n = 9) or partial (n = 1) ventilatory autonomy. In nine cases, diaphragm response was present at least on one side, with a normal latency (right: 15.6 +/- 1.5 milliseconds; left: 16.2 +/- 2.2 milliseconds). The test had 100% specificity (95% CI 52 to 100) and 90% sensitivity (95% CI 54 to 99) to predict the recovery of ventilatory activity. CONCLUSION: Electrophysiologic studies of the diaphragm in response to transcranial magnetic stimulation may help predict the recovery of central respiratory paralysis within 1 year.

Evaluation of the user-friendliness of 11 home mechanical ventilators.

The home ventilator market has grown in size and complexity. The aim of this study was to determine if common home ventilators are user-friendly for trained intensive care unit (ICU) physicians. Eleven ventilator models were tested by 13 ICU physicians without practical experience in home mechanical ventilation. Six tests were defined (start-up, unlocking, mode and setting recognition, mode change, pressure setting and alarm). For each test, the physicians were timed and their performance compared with a reference time established by a technician. The physicians also had to rate their global assessment of each machine on a visual analogue scale. The start-up test was the only test for which there was no significant difference between the physicians and the technician, except for two ventilators. The physicians were slower than the technician to unlock the ventilator and change the ventilatory mode, with some complete failures during these tests and heterogeneous results between physicians and between ventilators. Mistakes occurred in close to 50% of cases during the ventilatory mode and settings recognition test. The mean time for the most rapid of the physicians for all the tests was 58+/-53 s, compared with 15+/-9 s for the technician. In conclusion, trained intensive care unit physicians perform poorly when confronted with home mechanical ventilators without specific prior training. Therefore, it is hypothesised that the user-friendliness of home ventilators for other categories of users might be questionable.

Effects of upper airway anaesthesia on respiratory-related evoked potentials in humans.

Cortical potentials evoked by mid-inspiratory occlusion arise from numerous receptors, many of which are probably within the upper airway. Their precise nature is not known. The aim of the current study was to improve knowledge of this by studying the effects of topical upper airway anaesthesia on respiratory-related evoked potentials. Respiratory-related evoked potentials were described through the averaging of electroencephalogram (EEG) epochs following mid-inspiratory occlusions (C3-CZ; C4-CZ). A total of 21 healthy volunteers (13 male, aged 22-52 yrs) were studied during mouth breathing, before and after topical upper airway anaesthesia (lidocaine). Moreover, 15 subjects were studied during nose breathing with and without anaesthesia. Six subjects were studied whilst inhaling L-menthol. Typical potentials were present in all the subjects, their components featuring normal amplitudes and latencies. The route of breathing and upper airway anaesthesia did not modify the EEG responses to inspiratory occlusions, qualitatively or quantitatively, during mouth or nose breathing. L-menthol had no effect. Upper airway receptors sensitive to topical anaesthesia are unlikely to contribute significantly to mid-inspiratory occlusion-evoked potentials. On the contrary, deeper receptors, such as joint and muscle receptors, could contribute dominantly to these potentials.

[Removal of a tracheostomy in ventilator-dependent patients with neuromuscular disease]. / Sevrage de la trachéotomie chez des patients neuromusculaires dépendants d'une ventilation mécanique.

BACKGROUND: Ventilation via a tracheostomy is effective but very restricting in patients with neuromuscular disease. Return to non-invasive ventilation (NIV) is possible but this is not common practice, partly for want of standardised procedures ensuring a safe transition. METHODS: A procedure for transfer of ventilation via a tracheostomy to a mask has been developed based on the literature and local experience (feasibility of NIV, absence of laryngo-tracheal lesions, adequate leak compensation, effective cough). It has been tested in three patients with severe but stable neuromuscular disorders (chronic polyneuropathy in two cases and progressive spinal amyotrophy on one). RESULTS: The three patients were able to be extubated and established on domiciliary ventilation in 6,7 and 10 days, at the end of which all were discharged home. After 4 months in two cases and 6 months in the other no significant complications developed, the respiratory status under NIV was comparable to that previously under tracheostomy and the patients were satisfied with the change. CONCLUSION: The proposed algorithm seems to permit a rapid and safe transition from a tracheostomy to a mask. Large scale studies are needed to verify this concept and subsequently to identify within which group a similar approach may be correctly applied.

[Tracheostomy in intensive care: impact on prognosis and the influence of underlying chronic respiratory insufficiency]. / Trachéotomie en réanimation: pronostic et rôle d'une insuffisance respiratoire chronique.

INTRODUCTION: Numerous uncertainties remain concerning the place of tracheostomy in intensive care. Reluctance to perform tracheostomy is common, particularly in the presence of pre-existing chronic respiratory insufficiency (CRI), but some data suggest there may be benefits. The objective of this study was to evaluate the influence of tracheostomy on mortality in both intensive care and hospital, and to study the role of pre-existing CRI. MATERIAL AND METHODS: In a retrospective study of the records of 2901 patients admitted over a period of 5 years 882 were identified who had been intubated and ventilated. 127 patients who had had tracheostomies (T+) were compared with 755 who had not (T-), and with a sub-group of T- patients (T-app) matched for severity on admission (SAPSII). RESULTS: ICU and hospital mortality were significantly less in the T+ than the T-patients (28 vs 52% and 42 vs 59%) and the duration of stay was longer. This was equally true when matched for severity on admission when T+ were compared with T app (28 vs 49% and 42 vs 59%). Pre-existing CRI did not influence the outcomes of the tracheostomised patients, regardless of whether the CRI was obstructive, restrictive or neuro-muscular. CONCLUSIONS: Tracheostomy can, in certain groups of artificially ventilated patients and in certain care settings, be associated with a reduction in hospital mortality.

Vivid dreams, hallucinations, psychosis and REM sleep in Guillain-Barré syndrome.

We conducted a prospective controlled study of the clinical and biological determinants of the mental status abnormalities in 139 patients with Guillain-Barré syndrome (GBS) and 55 patients without GBS placed in the intensive care unit (ICU controls). There were mental status changes in 31% of GBS patients and in 16% of controls (odds ratio = 2.3; P = 0.04). In GBS patients, they included vivid dreams (19%), illusions (30%, including an illusory body tilt), hallucinations (60%, mainly visual) and delusions (70%, mostly paranoid). They appeared a median 9 days after disease onset (range 1-40 days, during the progression or the plateau of the disease), and lasted a median 8 days. Seven (16%) patients experienced the symptoms before their admission to the ICU. Hallucinations were frequently hypnagogic, occurring as soon as the patients closed their eyes. Autonomic dysfunction, assisted ventilation and high CSF protein levels were significant risk factors for abnormal mental status in GBS patients. CSF hypocretin-1 (a hypothalamic neuropeptide deficient in narcolepsy) levels, measured in 20 patients, were lower in GBS patients with hallucinations (555 +/- 132 pg/ml) than in those without (664 +/- 71 pg/ml, P = 0.03). Since the mental status abnormalities had dream-like aspects, we examined their association with rapid eye movement sleep (REM sleep) using continuous sleep monitoring in 13 GBS patients with (n = 7) and without (n = 6) hallucinations and 6 tetraplegic ICU controls without hallucinations. Although sleep was short and fragmented in all groups, REM sleep latency was shorter in GBS patients with hallucinations (56 +/- 115 min) than in GBS patients without hallucinations (153 +/- 130 min) and in controls (207 +/- 179 min, P < 0.05). In addition, sleep structure was highly abnormal in hallucinators, with sleep onset in REM sleep periods (83%), abnormal eye movements during non-REM sleep (57%), high percentages of REM sleep without atonia (92 +/- 22%), REM sleep behaviour disorders and autonomic dysfunction (100%), reminiscent of a status dissociatus. The sleep abnormalities, that were almost absent in non-hallucinated GBS patients, were not exclusively related to ICU conditions, since they also appeared out of ICU, and were reversible, disappearing when the mental status abnormalities vanished while the patients were still in ICU. In conclusion, the mental status abnormalities experienced by GBS patients are different from the ICU delirium, are strongly associated with autonomic dysfunction, severe forms of the disease and possibly with a transitory hypocretin-1 transmission decrease. Sleep studies suggest that mental status abnormalities are wakeful dreams caused by a sleep and dream-associated disorder (status dissociatus).

[Initiation and management of home mechanical ventilation]. / Mise en place et surveillance de l'assistance ventilatoire à domicile.

INTRODUCTION: Effective initiation and optimal monitoring of treatment are essential elements for successful home mechanical ventilation (HMV). STATE OF KNOWLEDGE: Ventilation is best initiated in a hospital setting. There is an enormous range of equipment available but there is little evidence pointing to the superiority of one device over another. Many problems can arise that lead to an interruption in HMV but often these can be resolved simply as discussed in this article. PERSPECTIVES: Unfortunately a number of pitfalls in management remain, the main one being the absence of accurate data about the sleep of patients on ventilators, which hinders optimal nocturnal management. Another problem is the lack of adaptation of equipment for use by handicapped patients. Finally the transfer of responsibility and workload to home carers including family members with disengagement by the hospital can also be a major milestone. CONCLUSION: Successful initiation and supervision is the key to effective home mechanical ventilation. Treatment is often abandoned because of pitfalls, mistakes and lack of knowledge. This article proposes means to improve these two important areas.

[What perception have smokers of nicotine and tar yields of cigarettes?]. / Quelle perception ont les fumeurs des rendements standards en nicotine et goudrons des cigarettes?

INTRODUCTION: Advertising information on cigarette package participate to the reduction of health risks from smoking. Impact on smokers has been poorly studied. This study intended to determine the smoker perception of nicotine and tar yields of cigarettes. METHODS: Consulting in an outpatient smoking cessation clinic, 171 smokers answered freely and spontaneously to a questionnaire evaluating their perception of nicotine and tar yields, cigarette consumption (number and brand), nicotine dependence. Simultaneously, biological tobacco markers were measured. RESULTS: The number of cigarettes, nicotine dependence and specific tobacco markers were not significantly different according to the cigarette type: "full savour", "light" or "ultra light". Women smoked less than men and 54% preferred "light" cigarettes versus 37% of men. These smokers were entering a tobacco cessation program, it was assumed they had lead a prior reflection about their smoking habits. Only 8% of them gave the correct values of nicotine and tar yields and 14% gave approximate values. Tar levels were highly underestimated. CONCLUSIONS: This study shows that smokers have actually no interest for nicotine and tar yields. As the new decree which modifies manufacture's obligation concerning the legal mentions, is applicable in January 2004 in France; our conclusion may change in the future.

Facilitation of the diaphragm response to transcranial magnetic stimulation by increases in human respiratory drive.

The human respiratory neural drive has an automatic component (bulbospinal pathway) and a volitional component (corticospinal pathway). The aim of this study was to assess the effects of a hypercapnia-induced increase in the automatic respiratory drive on the function of the diaphragmatic corticospinal pathway as independently as possible of any other influence. Thirteen healthy volunteers breathed room air and then 5 and 7% hyperoxic CO2. Cervical (cms) and transcranial (tms) magnetic stimulations were performed during early inspiration and expiration. Transdiaphragmatic pressure (Pdi) and surface electromyogram of the diaphragm (DiEMG) and of the abductor pollicis brevis (apbEMG) were recorded in response to cms and tms. During inspiration, Pdi,cms was unaffected by CO2, but Pdi,tms increased significantly with 7% CO2. During expiration, Pdi,cms was significantly reduced by CO2, whereas Pdi,tms was preserved. DiEMG,tms latencies decreased significantly during early inspiration and expiration (air vs. 5% CO2 and air vs. 7% CO2). DiEMG,tms amplitude increased significantly in response to early expiration-tms (air vs. 5% CO2 and air vs. 7% CO2) but not in response to early inspiration-tms. DiEMG,cms latencies and amplitudes were not affected by CO2 whereas 7% CO2 significantly increased the apbEMG,cms latency. The apbEMG,tms vs. apbEMG,cms latency difference was unaffected by CO2. In conclusion, increasing the automatic drive to breathe facilitates the response of the diaphragm to tms, during both inspiration and expiration. This could allow the corticospinal drive to breathe to keep the capacity to modulate respiration in conditions under which the automatic respiratory control is stimulated.

Unaltered respiratory-related evoked potentials after acute diaphragm dysfunction in humans.

Respiratory muscles play an important role in the origin of respiratory sensations. Data dissecting the role of the diaphragm and other inspiratory muscles are scarce. This study aimed to determine the impact of diaphragm dysfunction following inspiratory resistive loading on respiratory-related evoked potentials considered as a neurophysiological substrate of certain types of respiratory sensations. Altogether, nine subjects aged 25-50 yrs (six females) participated in the study. Transdiaphragmatic pressure output of cervical magnetic stimulation (with subdivision in oesophageal and gastric component), and respiratory-related evoked potentials (C3 and C4 derivations in the international 10-20 system) following mid-inspiratory occlusions were studied before and after an inspiratory-resistive loading challenge. Predominant diaphragm dysfunction was observed in seven subjects (average 28% reduction in transdiaphragmatic pressure, from 27.25-19.91 cmH2O, with increased oesophageal-to-gastric pressure ratio). The latencies and amplitudes of all the components of the respiratory-related evoked potentials were unchanged. The study concluded that predominant diaphragm fatigue does not affect respiratory-related evoked potentials.

Acute fungal pustulosis on a bedridden patient's back.

We report a particular dermatophytosis due to Trichophyton rubrum. A 61-year-old woman presented an eruption which quickly evolved within 48 h, consisting of papular annular patches surrounded by creamy white pustules, which sometimes coalesced. The eruption was exclusively located on the back. The rest of the body and skin examination was normal, and the patient had no temperature. The mycological sample revealed mycelial filaments in the direct microscopic examination and T. rubrum in the mycological culture. Only a few cases of pustular lesions due to T. rubrum are reported in the literature. The extensive character, the site and the inflammatory aspect of the lesions were very surprising. This clinical presentation is more frequent with geophilic and zoophilic organisms than with anthropophilic dermatophytes such as T. rubrum.

Parkinson's disease and sleepiness: an integral part of PD.

OBJECTIVE: To investigate the potential causes of excessive daytime sleepiness in patients with PD-poor sleep quality, abnormal sleep-wakefulness control, and treatment with dopaminergic agents. METHODS: The authors performed night-time polysomnography and daytime multiple sleep latency tests in 54 consecutive levodopa-treated patients with PD referred for sleepiness, 27 of whom were also receiving dopaminergic agonists. RESULTS: Sleep latency was 6.3 +/- 0.6 minutes (normal >8 minutes), and the Epworth Sleepiness score was 14.3 +/- 4.1 (normal <10). A narcolepsy-like phenotype (> or = 2 sleep-onset REM periods) was found in 39% of the patients, who were sleepier (4.6 +/- 0.9 minutes) than the other 61% of patients (7.4 +/- 0.7 minutes). Periodic leg movement syndromes were rare (15%, range 16 to 43/h), but obstructive sleep apnea-hypopnea syndromes were frequent (20% of patients had an apnea-hypopnea index >15/h; range 15.1 to 50.0). Severity of sleepiness was weakly correlated with Epworth Sleepiness score (r = -0.34) and daily dose of levodopa (r = 0.30) but not with dopamine-agonist treatment, age, disease duration, parkinsonian motor disability, total sleep time, periodic leg movement, apnea-hypopnea, or arousal indices. CONCLUSIONS: In patients with PD preselected for sleepiness, severity of sleepiness was not dependent on nocturnal sleep abnormalities, motor and cognitive impairment, or antiparkinsonian treatment. The results suggest that sleepiness-sudden onset of sleep-does not result from pharmacotherapy but is related to the pathology of PD.

Effects of muscle group recruitment on sniff transdiaphragmatic pressure and its components.

Measuring maximal sniff pressures is an easy way of assessing inspiratory muscle strength. During a static manoeuvre, the pattern of inspiratory muscle recruitment during a sniff can vary from one individual to another. We therefore assessed how voluntarily changing muscle recruitment would affect sniff oesophageal, gastric and transdiaphragmatic pressures (Pes,sn, Pga,sn and Pdi,sn, respectively). Ten normal subjects (age 27-38 years) performed natural sniff manoeuvres ("nat"), and preferentially diaphragmatic ("dia") or extradiaphragmatic ("extradia") sniff manoeuvres, after having learnt to dissociate between the inspiratory muscle groups. Abdominal displacements were monitored using a belt-mounted strain gauge. Natural patterns of muscle recruitment varied among subjects. On average, Pes,sn,nat was [median (range)] 81 (21-105) cmH2O. All of the subjects were able to modify inspiratory muscle recruitment voluntarily. Pes,sn was not significantly affected by the type of manoeuvre performed, as opposed to Pdi,sn, which, as expected, increased with both the diaphragmatic and extradiaphragmatic manoeuvres [Pdi,sn,dia 132 (99-157) cmH2O, Pdi,sn,extradia 96 (50-146) cmH2O, P<0.05]. Whatever the manoeuvre, there was no correlation between Pes and Pdi, but Pga and Pdi were correlated during both the diaphragmatic (r = 0.82, P < 0.05) and the extradiaphragmatic manoeuvre (r = 0.70, P < 0.05). Pes,sn may have limitations as an index of diaphragm function, but by showing its independence from inspiratory muscle recruitment, this study contributes to its validation as a robust index of global inspiratory muscle strength that is particularly well suited for follow-up studies. This should extend to Pes,sn substitutes measured at the airway opening.

Dysfunction of phrenic pacemakers induced by metallic rescue blankets.

Phrenic pacing can restore diaphragmatic contractions in patients with central respiratory paralysis. It relies on radiofrequency transmission of energy from an external unit to implanted receivers through circular coil antennas. The case of a patient is reported in whom severe hypoventilation occurred following the use of a metallic rescue blanket. The phenomenon was confirmed in two subsequent patients and during benchmark tests. Possible mechanisms include reflection and diffusion of high frequency waves by a Faraday-like effect. Patients with implanted devices relying on telemetric control or powering, and their care givers, should be warned against the use of metallic rescue sheets.

[Respiratory disorders during sleep in degenerative diseases of the brain stem]. / Troubles respiratoires du sommeil au cours des maladies dégénératives du tronc cérébral.

Sleep-disordered breathing may be present in patients with degenerative diseases affecting the brainstem. Indeed, this last structure contains the executive system of rapid eye movement (REM) sleep (tegmentum of the pons), of respiratory drive (medulla oblongata and pons) and motor neurons of upper airways dilators (fifth, seventh, ninth, tenth and twelfth cranial roots). Patients with Parkinson's disease suffer frequently from insomnia, partly caused by nocturnal motor disability, and from REM sleep behavior disorder. In 20 percent of the patients, excessive daytime sleepiness is caused by a sleep apnea syndrome, with a partly levodopa-dependent upper airway dysfunction. In 40 percent of the patients, sleepiness mimics a secondary narcolepsy and may be associated with hypnagogic hallucinations. During supranuclear palsy, REM sleep is progressively curtailed with rare sleep-disordered breathing. Patients with multiple systemic atrophy may present a nocturnal stridor caused by laryngeal palsy and benefit from tracheotomy or continuous nasal positive airway pressure. Seldom sleep and respiratory studies in genetic ataxic diseases suggest a normal respiratory drive, occasional diaphragmatic dysfunction and night hypopneas. During amyotrophic lateral sclerosis, the progressive loss of phrenic nerve leads to a diaphragmatic dysfunction, dyspnea and a lesser survival. Adequate ventilation is jeopardized during REM sleep with a consequent loss of this state.

Alveolar lymphocytosis in patients with chronic uveitis: relationship to sarcoidosis.

Bronchoalveolar lavage (BAL) is frequently performed in patients with suspected ocular sarcoidosis. This study describes the immunogenetical, immunological, radiological, and functional features of a subclinical alveolar lymphocytosis unrelated to sarcoidosis in patients with chronic uveitis. Two hundred and ten patients with chronic uveitis of unknown origin, who underwent fiber-optic bronchoscopy with BAL as part of a prospective protocol over a three-year period, were evaluable for retrospective analysis. Sixty-five patients had alveolar lymphocytosis: Sarcoidosis was diagnosed in 13 (6%) patients, whereas alveolar lymphocytosis was considered unrelated to sarcoidosis in 52 (25%). Alveolar lymphocytosis unrelated to sarcoidosis was not associated with radiologically detectable interstitial lung disease or pulmonary function impairment. CD4/CD8 lymphocyte ratio was 3.7 +/- 3.0. Total cell count, total lymphocyte, and CD4 lymphocyte percentage were significantly lower when compared with sarcoidosis-related alveolitis (129,000 +/- 80,000 vs. 218,000 +/- 117,000, p <0.05; 33.1% +/- 13.2 vs. 39.7% +/- 13.2, p <0.05; and 54.3% +/- 18.2 vs. 65.4% +/- 10.1, p <0.05, respectively). Patients with alveolar lymphocytosis unrelated to sarcoidosis were older (47.8 +/- 17.7 years vs. 42.7 +/- 14.2 years, p <0.05) and more likely to carry the HLA-B51 allele (19.7% vs. 7.1%, p <0.01) than patients with chronic uveitis without alveolar lymphocytosis. They did not appear to be at risk of developing clinically apparent interstitial lung disease on followup. We conclude that alveolar lymphocytosis is frequently observed in patients with chronic uveitis. It is generally unrelated to sarcoidosis and may then be associated with a distinctive immunogenetic phenotype.