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.

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]

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.

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.

[What perception have smokers of nicotine and tar yields of 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.

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.

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.

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.

[Respiratory disorders during sleep in degenerative diseases of the brain stem]

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.

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.

Improvement of sleep architecture in PD with subthalamic nucleus stimulation

High-frequency stimulation of the subthalamic nucleus (STN) was used to investigate the relationship of sleep disorders with motor handicap in PD. In 10 insomniac patients with PD, stimulation reduced nighttime akinesia by 60% and completely suppressed axial and early morning dystonia, but did not alleviate periodic leg movements (n = 3) or REM sleep behavior disorders (n = 5). Total sleep time increased by 47%; wakefulness after sleep onset decreased by 51 minutes. Insomnia in patients with PD may predominantly result from nighttime motor disability.

Pulmonary blood flow distribution in stage 1 chronic obstructive pulmonary disease

We investigated the hypothesis that lung blood flow distribution is modified in stage 1 chronic obstructive pulmonary disease (COPD). We compared patients with stage 1 COPD (n = 11) with restrictive patients with comparable blood gases (n = 7), to patients with low cardiac index with normal lungs (n = 11) and to control subjects (n = 11). Distribution of transit time (DTT) was computed by deconvolution from first pass radioactivity curves (albumin (99m)Tc) reconstructed from right and left ventricular regions of interest. Distribution descriptors, mean transit time (p < 0.05), standard deviation (p < 0.001), relative dispersion (p < 0.001), and kurtosis (p < 0.001) differed between groups (ANOVA). Cardiac index was the same in COPD and low CI groups but lower compared with normal subjects (p < 0.05). After normalization for cardiac output, the DTT of patients with COPD remained different from low CI and restrictive patients (p < 0.001). Therefore changes in DTT in patients with COPD compared with patients without COPD could not be explained on the basis of difference in cardiac output. Because P(O(2)), PC(O(2)), and pH were similar in COPD and restrictive groups, difference in distribution could not be explained either on the basis of blood gas data. We conclude that changes in DTT occurs in stage 1 COPD and cannot be explained by hypoxemia, hypercapnia, or acidosis alone but must relate to other structural or regulatory responses.

Traumatic coronary-pulmonary artery fistula, 23 years after a stab wound

We describe a 50-year-old man with onset of severe hemoptysis and anemia. Twenty-three years earlier, he had undergone a surgical procedure for a left thoracic wound as a result of a knife injury. Current diagnosis of aneurysm of the left ventricle and coronary-pulmonary artery fistula was made after coronary arteriography. The patient underwent resection of the aneurysm and repair of the fistula.

Assessment of upper airway dynamics in awake patients with sleep apnea using phrenic nerve stimulation

Phrenic nerve stimulation can reproduce during wakefulness the dissociation between upper airway and inspiratory muscles that is associated with obstructive sleep-related breathing disorders. This could provide a useful management tool in the study of passive upper airway (UA) dynamics during wakefulness in patients with the obstructive sleep apnea-hypopnea syndrome (OSAHS). To assess the feasibility of the technique in this setting, we studied the dynamics of diaphragm twitch-associated inspiratory flow in eight patients with OSAHS. Cervical magnetic stimulation (CMS) and bilateral anterior magnetic phrenic stimulation (BAMPS) were applied at end-expiration during exclusive nasal breathing. Electrical phrenic nerve stimulation (ES) proved not feasible. The driving pressure and the respiratory resistance at peak twitch esophageal pressure obtained at maximal stimulation intensity were significantly higher with BAMPS than with CMS. A twitch-flow limitation pattern was observed in seven of eight subjects; VI(max) values of flow-limited twitches obtained at 100% stimulation intensity was 0.81 +/- 0.5 L/s with BAMPS and 0.87 +/- 0.5 L/s with CMS (p = 0.4). The number of flow-limited BAMPS twitches dropped from an average 77.5% to 18.4% with nasal continuous positive airway pressure (CPAP) levels corresponding to the patient's home treatment. We conclude that (1) BAMPS is potentially a useful tool to evaluate the dynamics of flow through the passive UA in awake OSAHS patients, (2) BAMPS may be superior to CMS in evaluating UA properties in OSAHS.

Hallucinations, REM sleep, and Parkinson's disease: a medical hypothesis

BACKGROUND

Patients with PD can have disabling visual hallucinations associated with dopaminergic therapy. Sleep disorders, including vivid dreams and REM sleep with motor behaviors (RBD), are frequent in these patients.

METHODS

The association of hallucinations and REM sleep both at night and during the day was examined in 10 consecutive nondemented patients with long-standing levodopa-responsive PD and hallucinations. Seven patients presented with paranoia and paranoid delusions. Overnight sleep recordings and standard multiple daytime sleep latency test were performed. The results were compared to those of 10 similar patients with PD not experiencing hallucinations.

RESULTS

RBD was detected in all 10 patients with hallucinations and in six without. Although nighttime sleep conditions were similar in both groups, hallucinators tended to be sleepier during the day. Delusions following nighttime REM period and daytime REM onsets were observed in three and eight of the hallucinators, and zero and two of the others. Daytime hallucinations, coincident with REM sleep intrusions during periods of wakefulness, were reported only by hallucinators. Postmortem examination of the brain of one patient showed numerous Lewy bodies in neurons of the subcoeruleus nucleus, a region that is involved in REM sleep control.

CONCLUSION

The visual hallucinations that coincide with daytime episodes of REM sleep in patients who also experience post-REM delusions at night may be dream imagery. Psychosis in patients with PD may therefore reflect a narcolepsy-like REM sleep disorder.

Multiple organ failure complicating probable scrub typhus

This report describes a case of life-threatening acute respiratory distress syndrome with multiple organ failure complicating probable scrub typhus. Favorable outcome was associated with fluoroquinolone therapy. Scrub typhus should be suspected in travelers returning from Southeast Asia presenting with unexplained respiratory manifestations.

Linkage of hiccup with heartbeat

We explored a possible link between the cardiac cycle and the timing of recurrent hiccups in 10 patients with chronic, intractable hiccups. Recordings made during daytime naps in a sleep laboratory included sleep state; electrocardiogram; and respiration by means of a thermistor to detect airflow, bands around the rib cage and abdomen to assess expansion, and a bipolar surface electrode electromyogram over parasternal intercostal muscles. Hiccups could be detected on the abdominal bands and the parasternal electromyogram. The time of occurrence of each hiccup and each R wave in a continuous tracing of 100 or more hiccups were recorded and analyzed together with semiquantitive estimates of the phase of hiccup respiration. Whereas the hiccup rate ranged from approximately one-third to one-eighth of heart rate and was more variable than heart rate, hiccups showed a tendency, stronger in some subjects than others, to occur in midsystole. Variation in R-wave-R-wave (R-R) interval in association with hiccups was found in five patients. In three of these patients, hiccups were synchronized with respiration so that the cyclic change in R-R interval posthiccup could be explained as sinus arrhythmia, but, in two patients, the hiccups were not synchronized with respiration, so that hiccups are most likely responsible for the variation in heart rate. Also, the variation of R-R interval with hiccups suggests that there is some phasic autonomic efferent activity associated with hiccups.

Diaphragm and chest wall: assessment of the inspiratory pump with MR imaging-preliminary observations

Magnetic resonance (MR) imaging of the thorax with three-dimensional (3D) reconstruction and functional quantification was evaluated as a tool for structure-function evaluation of chest-wall mechanics. Good agreement was found between the corresponding spirometric and MR imaging values of lung volumes. Fast MR imaging of the thorax with 3D reconstruction should improve the ability to evaluate the inspiratory pump in clinical and research investigations.

Expiratory flow limitation as a determinant of orthopnea in acute left heart failure

OBJECTIVES

To assess the contribution of expiratory flow limitation (FL) in orthopnea during acute left heart failure (LHF).

BACKGROUND

Orthopnea is typical of acute LHF, but its mechanisms are not completely understood. In other settings, such as chronic obstructive pulmonary disease, dyspnea correlates best with expiratory FL and can, therefore, be interpreted as, in part, the result of a hyperinflation-related increased load to the inspiratory muscles. As airway obstruction is common in acute LHF, postural FL could contribute to orthopnea.

METHODS

Flow limitation was assessed during quiet breathing by applying a negative pressure at the mouth throughout tidal expiration (negative expiratory pressure [NEP]). Flow limitation was assumed when expiratory flow did not increase during NEP. Twelve patients with acute LHF aged 40-98 years were studied seated and supine and compared with 10 age-matched healthy subjects.

RESULTS

Compared with controls, patients had rapid shallow breathing with slightly increased minute ventilation and mean inspiratory flow. Breathing pattern was not influenced by posture. Flow limitation was observed in four patients when seated and in nine patients when supine. In seven cases, FL was induced or aggravated by the supine position. This coincided with orthopnea in six cases. Only one out of the five patients without orthopnea had posture dependent FL. Control subjects did not exhibit FL in either position.

CONCLUSIONS

Expiratory FL appears to be common in patients with acute LHF, particularly so when orthopnea is present. Its postural aggravation could contribute to LHF-related orthopnea.

Effect of low and high frequency thalamic stimulation on sleep in patients with Parkinson's disease and essential tremor

Continuous high frequency stimulation of the ventral intermediate nucleus of the thalamus (Vim), delivered through surgically implanted quadripolar electrodes, alleviates tremor in Parkinson's disease (PD) and essential tremor (ET). The Vim is adjacent to the thalamic reticular nuclei, where sleep spindles originate according to animal models. In order to determine whether Vim stimulation affects sleep spindles, six patients (4 PD, 2 ET), aged 60-69 years, were recorded on a control night and a stimulation night (130 Hz, 2-3 V; right stimulation in five patients and bilateral stimulation in one patient). Stimulation did not modify sleep quality or architecture. Sleep spindles were present and symmetrical in five out of six patients under stimulation. However, in one patient with a sustained 'thalamotomy-like effect' that abolished tremor, spindles were asymmetrical even without stimulation. In each patient, spindle density was similar on both nights (mean+/- SEM: 2.25+/-0. 61 spindles per min of stage 2 sleep vs. 1.84+/-0.31). In an attempt to promote sleep two different patterns of stimulation were applied in the region of ventrooralis posterior and reticularis nuclei in five patients in the awake state. Continuous low frequency stimulation (5 Hz, 0.1 V), and repeated trains of 15 Hz for 1 s every 15 s mimicking the pattern of physiological spindles, each failed to induce sleep or cortical synchronization. We conclude that Vim stimulation, unlike thalamotomy, selectively reduces tremor without altering sleep or sleep spindles. Our results also suggest that low frequency stimulation applied in the region of the reticular nuclei does not induce sleep.

Sleep disorders and diaphragmatic function in patients with amyotrophic lateral sclerosis

In amyotrophic lateral sclerosis (ALS), the progressive loss of upper and lower motor neurons leads to respiratory failure, often with predominant diaphragm dysfunction, and death. Because the diaphragm is the only active inspiratory muscle during rapid eye movement (REM) sleep, there is a high theoretical risk of respiratory disorders during REM sleep in patients with ALS. To assess this hypothesis, we studied sleep characteristics (polysomnography) in 21 patients with ALS, stratified according to the presence or absence of diaphragmatic dysfunction. Diaphragmatic dysfunction was defined as an absent or delayed diaphragm response to cervical or cortical magnetic stimulation, abdominal paradox, or respiratory pulse (Group 1, 13 patients). These patients did not differ in age, clinical course, or form (bulbar or spinal) from the eight others, who did not have diaphragmatic dysfunction (Group 2). REM sleep was reduced in Group 1 (7 +/- 7% of total sleep time; mean +/- SD) and normal in Group 2 (18 +/- 6%, p = 0.004). Apneas or hypopneas were rare in both groups. In Group 1, REM sleep was absent or minimal (less than 3 min) in five patients. An unusual and remarkable preservation of phasic inspiratory sternomastoid activation during REM was associated with longer REM sleep duration in six of the other patients with diaphragmatic dysfunction. Median survival time was dramatically shorter (217 d) in Group 1 than in Group 2 (619 d, p = 0.015).

Diaphragmatic dysfunction and dyspnoea in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive disorder of unknown origin. Respiratory involvement is the principal cause of death, and dyspnoea is a major source of discomfort. In this study, diaphragm function is described and its relationship with dyspnoea examined in 48 ALS patients (32 male, age 26-80 yrs). The detailed neurological and respiratory evaluation (clinical examination, pulmonary function tests, static pressures, mouth twitch pressures (Pm,t), electromyographic responses to phrenic nerve stimulation and cortical magnetic stimulation were analysed after stratification according to dyspnoea. Dyspnoeic (group I) and nondyspnoeic (group II) patients were similar, bulbar signs being more frequent in group I. Vital capacity was lower in group I (mean+/-SD 67.9+/-22.7 versus 87.9+/-15.6% of the predicted value, p=0.0028), as were maximal static inspiratory pressure (41+/-24 versus 60+/-27% pred, p=0.0242) maximal static inspiratory pressure (18+/-11 versus 32+/-14% pred, p=0.0042), and Pm,t (3.71+/-2.5 versus 7.26+/-3.45 cmH2O, p=0.0011). Abdominal (Abd) paradox and respiratory pulse were frequent in group I (15 of 25 and 14 of 25) but absent or rare in group II (0 of 23 and four of 23) (p<0.05). The electromyographic responses to phrenic and cortical stimulation were generally abnormal in group I but subnormal in group II. Multivariate analysis selected only signs of diaphragm dysfunction (namely, Abd paradox and abnormal electromyographic responses) as significant predictors of dyspnoea. It is concluded that dyspnoea in amyotrophic lateral sclerosis patients should prompt diaphragm function tests.

Respiratory high dependency care units (RHDCU) in France

The concept of intermediary intensive care units appeared in France with the progress of respiratory intensive care in the 1970s and an increment of the percentage of patients who were surviving an acute respiratory episode. It then became necessary to provide them with an optimal transition between the medical intensive care unit (ICU) and the home, thus explaining the emerging need for units of post-intensive care. At the present time, French health regulations recognize medical and surgical ICUs with a specific budget for equipment and nurses, and the specialized ICU which exists through a means share with the medical units (pulmonology, cardiology, etc.) inside which they are located. New regulations should make official the separation between medical and surgical intensive care units, intermediate (specialized) intensive care units and wards of reinforced follow-up, in a general perspective of improvement of the health network between the patient, home, and the different sectors of hospitalization (acute/chronic, public and private).

Effect of negative expiratory pressure on respiratory system flow resistance in awake snorers and nonsnorers

In spontaneously breathing subjects, intrathoracic expiratory flow limitation can be detected by applying a negative expiratory pressure (NEP) at the mouth during tidal expiration. To assess whether NEP might increase upper airway resistance per se, the interrupter resistance of the respiratory system (Rint,rs) was computed with and without NEP by using the flow interruption technique in 12 awake healthy subjects, 6 nonsnorers (NS), and 6 nonapneic snorers (S). Expiratory flow (V) and Rint,rs were measured under control conditions with V increased voluntarily and during random application of brief (0.2-s) NEP pulses from -1 to -7 cmH(2)O, in both the seated and supine position. In NS, Rint,rs with spontaneous increase in V and with NEP was similar [3.10 +/- 0.19 and 3.30 +/- 0.18 cmH(2)O x l(-1) x s at spontaneous V of 1.0 +/- 0.01 l/s and at V of 1.1 +/- 0.07 l/s with NEP (-5 cmH(2)O), respectively]. In S, a marked increase in Rint,rs was found at all levels of NEP (P < 0.05). Rint,rs was 3.50 +/- 0.44 and 8.97 +/- 3.16 cmH(2)O x l(-1) x s at spontaneous V of 0.81 +/- 0.02 l/s and at V of 0.80 +/- 0.17 l/s with NEP (-5 cmH(2)O), respectively (P < 0.05). With NEP, Rint,rs was markedly higher in S than in NS both seated (F = 8.77; P < 0.01) and supine (F = 9.43; P < 0.01). In S, V increased much less with NEP than in NS and was sometimes lower than without NEP, especially in the supine position. This study indicates that during wakefulness nonapneic S have more collapsible upper airways than do NS, as reflected by the marked increase in Rint,rs with NEP. The latter leads occasionally to an actual decrease in V such as to invalidate the NEP method for detection of intrathoracic expiratory flow limitation.

Inspiratory flow dynamics during phrenic nerve stimulation in awake normals during nasal breathing

The loss of upper airway (UA) dilators preactivation before inspiratory muscle contraction is an important determinant of the pathophysiology of obstructive sleep apnea. We hypothetized that phrenic nerve stimulation could provide a practical way to explore the effects of the dissociation between UA dilators and inspiratory muscles, and possibly to determine UA critical closing pressure during wakefulness. The pattern of inspiratory airflow was therefore studied in normal awake subjects during diaphragm twitches induced by either electrical phrenic stimulation (ES) or cervical magnetic stimulation (CMS) (n = 9) and with and without a nasal stent during ES (n = 7). End-expiratory stimulations applied during exclusive nasal breathing induced 200 to 300 ms twitch inspiratory flow. The average maximal twitch flow of flow-limited twitches was higher during CMS than ES (1.18 +/- 0.29 L.

Dynamic hyperinflation and flow limitation during methacholine-induced bronchoconstriction in asthma

Although persistent activation of the inspiratory muscles and narrowing of the glottic aperture during expiration have been indicated as relevant mechanisms leading to dynamic hyperinflation in acute asthma, expiratory flow limitation (EFL) has recently been proposed as a possible triggering factor for increasing endexpiratory lung volume (EELV). To establish whether the attainment of maximal flow rate during tidal expiration could elicit dynamic elevation of EELV, breathing pattern, change in EELV by measuring inspiratory capacity (IC) and occurrence of EFL by the negative expiratory pressure (NEP) method were monitored in 10 stable asthmatic subjects during methacholine-induced, progressive bronchoconstriction in seated position. Change in dyspnoea was scored using the Borg scale. At maximum response forced expiratory volume in one second (FEV1) fell on average by 45+/-2% (p<0.001 versus control), while IC decreased 29+/-2%, (by 0.89+/-0.07 L, (p<0.01 versus control)). Only 2 subjects exhibited EFL at the end of methacholine challenge. In 7 subjects EELV started to increase before the occurrence of EFL. Dyspnoea, which increased from 0.2+/-0.1 to 5.5+/-1.0 (Borg scale) at maximum response (p<0.001), was significantly related to the level of bronchoconstriction as assessed by change in (delta)FEV1 (r=0.72; p<0.001) and to dynamic hyperinflation as measured by deltaIC (r=0.50; p<0.001). However, for both deltaFEV1 and deltaIC the slope of the relationship with increasing dyspnoea was highly variable among the subjects. It is concluded that in acute methacholine-induced bronchoconstriction, dynamic hyperinflation may occur in the absence of expiratory flow limitation and that expiratory flow limitation does not represent the triggering factor to generate dynamic hyperinflation. In these circumstances, dyspnoea appears to be related to the increase in end-expiratory lung volume and not to the onset of expiratory flow limitation.

Long term effects of inhaled corticosteroids in chronic obstructive pulmonary disease: a meta-analysis

BACKGROUND

The role of inhaled corticosteroids in the long term management of chronic obstructive pulmonary disease (COPD) is still unclear. A meta-analysis of the original data sets of the randomised controlled trials published thus far was therefore performed. The main question was: "Are inhaled corticosteroids able to slow down the decline in lung function (FEV1) in COPD?"

METHODS

A Medline search of papers published between 1983 and 1996 was performed and three studies were selected, two of which were published in full and one in abstract form. Patients with "asthmatic features" were excluded from the original data. Ninety five of the original 140 patients treated with inhaled corticosteroids (81 with 1500 micrograms beclomethasone daily, six with 1600 micrograms budesonide daily, and eight with 800 micrograms beclomethasone daily) and 88 patients treated with placebo (of the initial 144 patients) were included in the analysis. The effect on FEV1 was assessed by a multiple repeated measurement technique in which points of time in the study and treatment effects (inhaled corticosteroids compared with placebo) were investigated.

RESULTS

No baseline differences were observed (mean age 61 years, mean FEV1 45% predicted). The estimated two year difference in prebronchodilator FEV1 was +0.034 l/year (95% confidence interval (CI) 0.005 to 0.063) in the inhaled corticosteroid group compared with placebo. The postbronchodilator FEV1 showed a difference of +0.039 l/year (95% CI -0.006 to 0.084). No beneficial effect was observed on the exacerbation rate. Worsening of the disease was the reason for drop out in four patients in the treatment group compared with nine in the placebo group. In the treatment group six of the 95 subjects dropped out because of an adverse effect which may have been related to the treatment compared with two of the 88 patients in the placebo group.

CONCLUSIONS

This meta-analysis in patients with clearly defined moderately severe COPD showed a beneficial course of FEV1 during two years of treatment with relatively high daily dosages of inhaled corticosteroids.

Effect of salbutamol on dynamic hyperinflation in chronic obstructive pulmonary disease patients

Expiratory flow limitation (EFL), which promotes dynamic hyperinflation and increased work of breathing, often occurs in chronic obstructive pulmonary disease (COPD). The purpose of this study was to assess the effect of bronchodilators on EFL and end-expiratory lung volume in patients with moderate-to-severe COPD. EFL was assessed by applying negative expiratory pressure (NEP) at the mouth during tidal expiration. EFL was present when expiratory flow did not increase or increased only in the early phase of expiration with NEP. In 18 patients (age 65+/-2 yrs; forced expiratory volume in one second (FEV1)=45+/-4% predicted) pulmonary function tests and a series of NEP (-3.5 cmH2O) test breaths were performed at rest in a sitting position before and 20 min after inhalation of 400 microg of salbutamol. EFL was detected in 11 patients and persisted after salbutamol in all of these flow-limited (FL) patients. After bronchodilator administration FL patients exhibited a significant decrease in functional residual capacity (FRC) associated with an increase in inspiratory capacity (IC). In contrast, no changes in FRC and IC were observed in the seven non flow-limited (NFL) patients after administration of salbutamol. Except for one NFL patient, the other 17 patients (six NFL and 11 FL) had no reversibility of their bronchial obstruction (delta FEV1 <10% pred). In conclusion, patients with chronic obstructive pulmonary disease and expiratory flow limitation, even if nonresponders in terms of forced expiratory volume in one second, may benefit from bronchodilators because they can breathe, still in a flow-limited manner, at a lower lung volume.

Clinical utility of an amplification test based on ligase chain reaction in pulmonary tuberculosis

We evaluated the sensitivity and specificity of a new semiautomated direct amplification test (DAT), the LCx-MTB, for the diagnosis of pulmonary tuberculosis (TB) and assessed its positive predictive value by focusing on patients with high clinical and radiologic suspicion of pulmonary TB. Respiratory tract specimens from 32 consecutive patients with high suspicion of active pulmonary TB (case patients) and from 204 control patients were cultured for Mycobacterium tuberculosis and tested by LCx-MTB. Sensitivity and specificity of LCx-MTB when compared with culture was, respectively, 80 and 98%. Pulmonary TB was confirmed in the 32 case patients without knowledge of the LCx results: 18 patients were smear- and culture-positive for M. tuberculosis, and all gave at least one specimen that was LCx-positive. Eight patients were smear-negative culture-positive, and seven gave at least one LCx-positive specimen. LCx-MTB was negative in all the specimens obtained from six patients with smear- and culture-negative TB. A positive LCx-MTB result in a smear negative specimen was 100% predictive that at least one of the case patients' specimens would yield M. tuberculosis. As a consequence, knowledge of the LCx-MTB results at the time of specimen collection could have hastened the start of the antituberculosis therapy in three (21%) smear-negative case patients and could have avoided unnecessary invasive diagnostic procedures in four (29%). We conclude that the sensitivity of LCx-MTB in detecting M. tuberculosis DNA in respiratory tract specimens is similar to other DATs, that LCx-MTB is a reliable test for confirmation of TB in smear-positive patients and that LCx-MTB could be beneficial as a diagnostic step in smear-negative patients with a high suspicion of pulmonary TB.

Preliminary results of collapse therapy with plombage for pulmonary disease caused by multidrug-resistant mycobacteria

Seven patients underwent collapse therapy with polystyrene sphere plombage for pulmonary disease caused by multidrug-resistant mycobacteria. Four patients were infected with multidrug-resistant strains of Mycobacterium tuberculosis, two with Mycobacterium xenopi, one with Mycobacterium avium. All patients were heavily pretreated before surgery, had extensive, bilateral cavitary disease and were considered unsuitable for resection because of extensive disease or functional respiratory impairment. Six patients had active disease at time of surgery. Collapse therapy with insertion of six to 18 spheres resulted in long-standing bacteriological conversion in six patients. Collapse therapy was unilateral in six and bilateral in one. No immediate postoperative complication or death was observed. Hospital stay was short (mean 12 d). Collapse therapy is a conservative alternative therapy in patients with pulmonary disease caused by multidrug-resistant mycobacteria at high risk of treatment failure considered unsuitable for pulmonary resection.

Cervical magnetic stimulation as a method to discriminate between diaphragm and rib cage muscle fatigue

Inspiratory muscle fatigue can probably determine hypercapnic respiratory failure. Diaphragm fatigue is detected by electrical phrenic stimulation (ELS), but there is no simple tool to assess rib cage muscle (RCM) fatigue. Cervical magnetic stimulation (CMS) costimulates the phrenic nerves and RCM. We reasoned that changes in transdiaphragmatic pressure twitch (Pdi,tw) with CMS and ELS should be different after selective diaphragm vs. RCM fatigue. Five volunteers performed inspiratory resistive tasks while voluntarily uncoupling diaphragm and RCM. Baseline Pdi,twELS and Pdi,twCMS were 28.57 +/- 1.68 and 32.83 +/- 2.92 cmH2O. After selective diaphragm loading, Pdi,twELS and Pdi,twCMS were reduced by 39 and 26%, with comparable decreases in gastric pressure twitch (Pga,tw). Esophageal pressure twitch (Pes,tw) was better preserved with CMS. Therefore Pes,tw/Pga,tw was lower with ELS than CMS (-1.24 +/- 0.16 vs. -1.73 +/- 0.11, P = 0.05). After selective RCM loading, there was no diaphragm fatigue, but Pes,twCMS was significantly reduced (-30%). These findings support the role of rib cage stiffening by CMS-related RCM contraction in the ELS-CMS differences and suggest that CMS can be used to assess RCM fatigue.

Use of DNA fingerprinting for primary surveillance of nosocomial tuberculosis in a large urban hospital: detection of outbreaks in homeless people and migrant workers

SETTING

A large urban teaching hospital in the southeast of Paris.

OBJECTIVE

Primary surveillance of nosocomial transmission of tuberculosis (TB) by systematic restriction fragment length polymorphism analysis (RFLP) of isolates (n = 161) recovered from smear-positive pulmonary TB patients identified from 1 March 1993 to 28 February 1994, and from all TB patients (with any form of tuberculous infection) identified from 1 March 1994 to 30 April 1995.

RESULTS

Systematic RFLP analysis revealed 12 clusters of patients (n = 40) infected by strains of Mycobacterium tuberculosis showing matching RFLP patterns. None of the isolates were multidrug-resistant. Compared with non-clustered patients, clustered patients were more likely to be homeless (55% vs 19%, P < or = 0.001), or Africans living in hostels for migrant workers (20% vs 6%, P = 0.01), and had fewer previous admissions to hospital (12% vs 28%, P = 0.05). Further epidemiological investigations showed that the clustered TB cases actually resulted not from nosocomial transmission, but from transmission in the community, very likely in homeless shelters and hostels for migrant workers.

CONCLUSION

No nosocomial transmission of TB was identified among the patients included during the study period. Systematic RFLP analysis using hospital-based sampling can detect the spread of TB in specific environments in the community where transmission is occurring.

Application of negative expiratory pressure during expiration and activity of genioglossus in humans

The application of negative expiratory pressure (NEP) at end expiration has been shown to cause reflex-mediated activation of the genioglossus muscle in awake humans. To test whether a reflex contraction of pharyngeal dilator muscles also occurs in response to NEP applied in early expiration, the effect on genioglossus muscle reflex activity of NEP pulses of 500 ms, given 0.2 s after the onset of expiration and during the end-expiratory pause, was assessed in 10 normal awake subjects at rest. The raw and integrated surface electromyogram of the genioglossus (EMGgg) was recorded with airflow and mouth pressure under control conditions and with NEP ranging from -3 to -10 cmH2O. Intraoral EMGgg was also recorded under the same experimental conditions in two subjects. The application of NEP at the end-expiratory pause elicited a consistent reflex response of EMGgg in seven subjects with a mean latency of 68 +/- 5 ms. In contrast, when NEP was applied at the onset of expiration, EMGgg reflex activity was invariably observed in only one subject. No relationship was found between steady increase or abrupt fall in expiratory flow and the presence or the absence of a reflex activity of genioglossus during sudden application of NEP at the beginning of expiration. Our results show that a reflex activity of genioglossus is elicited much more commonly during application of NEP at the end rather than at the onset of expiration. These findings also suggest that when NEP is applied in early expiration to detect intrathoracic flow limitation the absence of upper airways narrowing does not imply the occurrence of a reflex-mediated activation of genioglossus and vice versa.

[Forced expiration. Various current concepts, 50 years after Robert Tiffeneau]

One hundred and fifty years after the original description of spirometry by Hutchinson and 50 years after the definition of his famous ratio by Tiffeneau, a certain number of physiological advances have enabled a better understanding of the determinants of the forced expired manoeuvre and to mitigate some of its inconveniences. This review focuses on three of these advances. The first is the influence of an inspiratory manoeuvre which precedes a forced expiration, on the expiratory flow. This influence is probably a consequence of viscoelastic phenomena and impose some strains on standardisation in current practice. The second is the possibility of detecting in a reproducible and simple fashion, without the need for co-operation on the part of the subject, a limitation in expiratory flow by the application of a negative expiratory pressure at the opening of the airways (NEP for negative expiratory pressure). The third is the possibility to verify in a simple fashion the quality of the expiratory performance achieved by the patient and thus to detect an insufficient effort in the force of a falling expiratory flow.

CD8+ lymphocytic pneumonitis in a patient receiving cyproterone acetate

A large number of drugs can induce pulmonary disease. We report the case of a female patient who was receiving cyproterone acetate for severe hirsutism. After 4 months of cyproterone therapy, she had dyspnea, pulmonary infiltrates, and a restrictive ventilatory defect. Bronchoalveolar lavage showed CD8+ lymphocytosis as well as increased neutrophils and eosinophils, a profile highly suggestive of an iatrogenic process. The patient showed no other significant clinical or biologic abnormality. Symptoms and functional abnormalities disappeared after withdrawal of cyproterone and reappeared after its reintroduction. This suggests that cyproterone acetate, a substance used to treat hirsutism and prostate cancer and in the composition of certain oral contraceptives, can be added to the list of drugs that may cause lymphocytic pneumonitis.

Influence of neck muscles on mouth pressure response to cervical magnetic stimulation

Measurement of mouth pressure (Pm) in response to electrical phrenic nerve stimulation (Es) provides a simple noninvasive means to assess diaphragm function. An even simpler measure would be to use the Pm twitch response (Pm,t) to cervical magnetic stimulation (CMS) rather than to Es. Because CMS coactivates the diaphragm and inspiratory neck muscles (INM), CMS-Pm,t accurately reflects diaphragm function only if the corresponding INM contraction does not produce inspiratory pressures by itself. In patients with recent-onset bilateral diaphragm paralysis, it has been demonstrated that CMS-Pm,t was indeed zero; however, INM hypertrophy could change this situation and lead CMS-Pm,t to overestimate the performance of the diaphragm. To address this issue, we studied nine patients with amyotrophic lateral sclerosis (ALS) who had evidence of diaphragmatic paralysis and compensatory hypertrophy and hyperactivity of inspiratory neck muscles. The response to CMS was described in terms of diaphragm electromyogram (EMG), Pm, and abdominal (AB) and rib cage (RC) motion. No EMG response to CMS could be observed in most cases, and CMS was always associated with AB paradox. Nevertheless, a negative Pm,t swing was recorded with an amplitude of -2.6 +/- 1.0 cm H2O (mean +/- SD). We conclude that inspiratory neck muscle hypertrophy can significantly influence the Pm response to CMS. This should be taken into account when using the CMS-Pm combination in patients with possible chronic diaphragm dysfunction.

Neuromuscular blockade with acute respiratory failure in a patient receiving cibenzoline

Cibenzoline is a class Ic antiarrhythmic agent that can be used to treat supraventricular arrhythmias. A case is reported of cibenzoline overdose in a patient with impaired renal function, leading not only to the usual cardiac and metabolic symptoms (bradycardia and hypoglycaemia), but also to a myastheniform syndrome with acute respiratory failure. Neuromuscular blockade was demonstrated by repetitive supramaximal stimulation of the median nerve, and diaphragmatic involvement was evidenced by applying the same protocol to the phrenic nerve. Muscle strength recovered as serum cibenzoline levels decreased, allowing the patient to be weaned from the ventilator. This observation suggests that cibenzoline, like other antiarrhythmic agents, can be responsible for neuromuscular blockade, and should therefore be used with caution in patients with neuromuscular and respiratory diseases or with impaired renal function.

A phase II study of cisplatin, 5-fluorouracil, leucovorin, and etoposide in advanced non-small-cell lung cancer

The aim of this study was to define the efficacy of a combination of cisplatin, 5-fluorouracil (5-FU), leucovorin, and etoposide (VP-16) in locally advanced or metastatic non-small-cell lung cancer (NSCLC). From September 1991 to November 1994, 28 patients were treated with cisplatin, 100 mg/m2 i.v. on day 1; 5-FU and leucovorin, 500 mg/m2 on days 1, 2, 3, and 4 by i.v. continuous infusion; and VP-16, 70 mg/m2 i.v. on days 1, 2, 3, and 4 (combination, PFL-VP-16). Cycles were repeated every 3 weeks. There were 22 men and six women. The median age was 58 (range, 41-76). All had measurable diseases (one was stage IIIA, six were IIIB, and 21 were IV). None had previously received chemotherapy for metastatic disease. There was one complete response and six partial responses, for an overall response rate of 25% (95% confidence interval 9-41%). The median response duration and the overall survival were 8 and 9 months, respectively. Limiting toxicity was myelosuppression and oral mucositis. Grade 3 or 4 leucopenia was observed in 20% of all of the 95 cycles administered, and oral mucositis in 13%. No grade 3 or 4 renal toxicity occurred, and neurologic toxicities were limited (3% of the 28 patients experienced grade 3). PFL-VP-16 is active and can easily be administered to patients with advanced NSCLC. However, according to the results obtained with this schedule, VP-16 does not increase either response rate or survival compared with the regimen previously described by Vokes et al. (PFL).

Comparison of magnetic and electrical phrenic nerve stimulation in assessment of phrenic nerve conduction time

Cervical magnetic stimulation (CMS), a nonvolitional test of diaphragm function, is an easy means for measuring the latency of the diaphragm motor response to phrenic nerve stimulation, namely, phrenic nerve conduction time (PNCT). In this application, CMS has some practical advantages over electrical stimulation of the phrenic nerve in the neck (ES). Although normal ES-PNCTs have been consistently reported between 7 and 8 ms, data are less homogeneous for CMS-PNCTs, with some reports suggesting lower values. This study systematically compares ES- and CMS-PNCTs for the same subjects. Surface recordings of diaphragmatic electromyographic activity were obtained for seven healthy volunteers during ES and CMS of varying intensities. On average, ES-PNCTs amounted to 6.41 +/- 0.84 ms and were little influenced by stimulation intensity. With CMS, PNCTs were significantly lower (average difference 1.05 ms), showing a marked increase as CMS intensity lessened. ES and CMS values became comparable for a CMS intensity 65% of the maximal possible intensity of 2.5 Tesla. These findings may be the result of phrenic nerve depolarization occurring more distally than expected with CMS, which may have clinical implications regarding the diagnosis and follow-up of phrenic nerve lesions.

Putative projection of phrenic afferents to the limbic cortex in humans studied with cerebral-evoked potentials

Respiratory sensations may rely in part on cortical integration of respiratory afferent information. In an attempt to study such projections, we recorded evoked potentials at scalp and cervical sites in 10 normal volunteers undergoing transcutaneous phrenic stimulation (0.1-ms square pulses, intensity liminal for diaphragmatic activation, series of 600 shocks at 2 Hz). A negative cerebral component of peak latency (12.79 +/- 0.54 ms; N13) was constant, and a negative spinal component (7.09 +/- 1.04 ms; N7) could also be recorded, all results being reproducible over time. Monitoring of cardiac frequency, skin anesthesia, and stimulation adjacent to the phrenic nerve made the phrenic origin of N7 and N13 the foremost hypothesis. Increasing stimulation frequency and comparison with median nerve stimulation provided arguments for the neural nature of the signals and their cerebral origin. Recordings from intracerebral electrodes in a patient showed a polarity reversal of the evoked potentials at the level of the cingulate gyrus. In conclusion, phrenic stimulation could allow one to study projections of phrenic afferents to the central nervous system in humans. Their exact site and physiological meaning remain to be clarified.

Modafinil in obstructive sleep apnea-hypopnea syndrome: a pilot study in 6 patients

We studied the effects of modafinil, a vigilance-enhancing drug, on excessive daytime sleepiness, memory, night sleep and respiration in 6 patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) using a double-blind random cross-over design with 24-hour polysomnography, verbal memory test and a 5-week sleep-wake diary kept by the patients. There were two 2-week treatment periods in which either modafinil or placebo was used; they were separated by a 1-week wash-out period. Our results show that modafinil reduces daytime sleep duration, lengthens the duration of subjective daytime vigilance and improves long-term memory in patients with OSAHS without modifying night sleep and respiration events.