Automatic air-leak compensation in neuromuscular patients: a feasibility study.

Air leaks often result in alveolar hypoventilation in mechanically ventilated patients with neuromuscular disease. The primary objective of this study was to assess the feasibility, efficacy and tolerance of a ventilator equipped with an automated air-leak compensation system in a clinical situation. Fourteen neuromuscular patients with nocturnal air leaks during home ventilation were included in a prospective randomised crossover study. A modified VS Ultra ventilator was studied during two consecutive nights and patients were randomly ventilated with and without a leak-compensation system, respectively. Tolerance, minute ventilation, blood gas values, sleep parameters, and nocturnal oxygen saturation were assessed. Leak compensation significantly increased the mean inspiratory and expiratory tidal volumes (731+/-312 vs. 1094+/-432 ml [p=0.002] and 329+/-130 vs. 496+/-388 ml [p=0.006], respectively) and inspiratory and expiratory flows (51.7+/-8.2 vs. 61.8+/-12.4 l/min [p=0.016] and 63.3+/-26.2 vs. 83.3+/-37.8 l/min [p=0.013], respectively). The system acted by increasing both inspiratory time (from 1355+/-230 to 1527+/-159 ms, p=0.038) and inspiratory pressure (from 14.0+/-2.8 to 18.3+/-3.4 cm H(2)O, p=0.002). Leak compensation improved arterial PCO(2) (6.18+/-0.9 vs. 5.21+/-1.0 kPa, p=0.004), slow-wave-sleep latency (119+/-69 vs. 87+/-35 min, p=0.04), and tolerance. Air-leak compensation is feasible and may produce beneficial effects in neuromuscular patients. The automatic air-leak compensation system tested here should be evaluated in long-term efficacy and tolerance studies and compared to other ventilation modes capable of compensating for leaks, such as pressure support.

Evaluation of a stair-climbing power wheelchair in 25 people with tetraplegia.

OBJECTIVE: To compare the performance of a power wheelchair with stair-climbing capability (TopChair) and a conventional power wheelchair (Storm3). DESIGN: A single-center, open-label study. SETTING: A physical medicine and rehabilitation hospital. PARTICIPANTS: Patients (N=25) who required power wheelchairs because of severe impairments affecting the upper and lower limbs. INTERVENTIONS: Indoor and outdoor driving trials with both devices. Curb-clearing and stair-climbing with TopChair. MAIN OUTCOME MEASURES: Trial duration and Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) tool; number of failures during driving trials and ability to climb curbs and stairs. RESULTS: All 25 participants successfully completed the outdoor and indoor trials with both wheelchairs. Although differences in times to trial completion were statistically significant, they were less than 10%. QUEST scores were significantly better with the Storm3 than the TopChair for weight (P=.001), dimension (P=.006), and effectiveness (P=.04). Of the 25 participants, 23 cleared a 20-cm curb without help, and 20 climbed up and down 6 steps. Most participants felt these specific capabilities of the TopChair--for example, curb clearing and stair climbing-were easy to use (22/25 for curb, 21/25 for stairs) and helpful (24/25 and 23/25). A few participants felt insecure (4/25 and 6/25, respectively). CONCLUSIONS: The TopChair is a promising mobility device that enables stair and curb climbing and warrants further study.

Intermittent positive-pressure breathing effects in patients with high spinal cord injury.

OBJECTIVE: To determine whether intermittent positive-pressure breathing (IPPB) improved lung compliance, work of breathing, and respiratory function in patients with recent high spinal cord injury (SCI). DESIGN: An unblinded randomized crossover trial. SETTING: Rehabilitation hospital. PARTICIPANTS: Patients (N=14) with SCI caused by trauma within the last 6 months and located between C5 and T6. INTERVENTION: Two months of IPPB and 2 months of conventional treatment were evaluated prospectively in random order in patients with SCI. MAIN OUTCOME MEASURES: Noninvasive lung function tests and arterial blood gas measurements were obtained repeatedly in all patients. Repeated measurements of dynamic lung compliance and work of breathing as measured by computing the area enclosed between the inspiratory esophageal pressure-tidal volume curve, and the theoretical chest wall static pressure-volume curve were performed in 7 patients. RESULTS: IPPB had no long-term effects on vital capacity (52.1%+/-11.3% vs 54.5%+/-12.5%, after conventional treatment and IPPB, respectively; P=.27), lung compliance (66.4+/-48.9 mL/cmH(2)O vs 70.3+/-38.4 mL/cmH(2)O; P=.56), or other lung function tests. IPPB did not exert short-term effects on lung compliance or work of breathing. CONCLUSIONS: IPPB produced no immediate or long-term improvements in lung function or ventilatory mechanics in patients with recent SCI. (ClinicalTrials.gov identifier: NCT00476866.).

Home trials of a speech synthesizer in severe dysarthria: patterns of use, satisfaction and utility of word prediction.

OBJECTIVE: The aim of this study was to evaluate a speech synthesizer with respect to patterns of use and satisfaction, during a 2-month trial at home, and the usefulness of the word prediction function. DESIGN: Prospective study. PARTICIPANTS: Of the 24 patients with severe dysarthria recruited, 10 completed the study. Five patients had cerebral palsy, 3 amyotrophic lateral sclerosis, one locked-in syndrome, and one anoxic brain damage. Mean age was 32 (standard deviation 21) years (range 9-66 years). METHODS: Each participant received 10 hours of training with the device (Dialo) and then used it at home for 2 months. The main outcome measures were: level of use recorded by the device, Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) satisfaction score (maximum = 5), and time needed to take dictations of standard-dictionary and personal-dictionary words with and without word prediction. RESULTS: Level of use varied widely across participants. Overall satisfaction at the end of the home trial was high, with a mean QUEST score of 3.4 (SD 1) and was related to the level of use of the device. Level of satisfaction at the end of the training session could not predict the level of use at home. No significant differences were found in dictation-taking times with and without word prediction. However, 6 of the 10 patients took dictation faster with than without word prediction. CONCLUSION: This study provides the first evidence supporting the benefits of a speech synthesizer used at home for several weeks. Word prediction is useful for some patients even if increase in dictation speed did not reach significance.

Hand versus mouth for call-bell activation by DMD and Becker patients.

Severe hand dysfunction is common in patients with Duchenne muscular dystrophy (DMD) and may preclude the use of conventional call-bells. We prospectively evaluated a call-bell with two hand-controlled interfaces (push-button and key-pinch) and two mouth-controlled interfaces (sip-or-puff) in 32 consecutive DMD and Becker patients. Patients called intentionally 348 times, using the sip-or-puff device 237 times and the hand-controlled interfaces 147 times. Use of the hand-controlled interfaces correlated with key-pinch strength (R=0.366; P=0.04). Six patients reported being unable to call with the hand interfaces and five patients reported temporary call failure due to inaccessibility of the sip-or-puff interface. Ease-of-use scores on a visual analogue scale were best for puff, followed by sip then key-pinch interrupter and push-button (8.7+/-2.1, 7.5+/-2.7, 6.2+/-3.9, and 0.5+/-2.0 respectively; ANOVA: P<0.00001). In conclusion sip-or-puff devices should be considered more often to provide neuromuscular patients with greater independence.

Breathing-swallowing interaction in neuromuscular patients: a physiological evaluation.

RATIONALE: Malnutrition and aspiration are major problems in patients with neuromuscular disease. Because impaired swallowing contributes to malnutrition, means of improving swallowing are needed. OBJECTIVES: To investigate interactions between breathing and swallowing in neuromuscular disorders and to evaluate the impact of mechanical ventilation (MV) on swallowing in tracheostomized patients. METHODS: We studied 10 healthy individuals and 29 patients with neuromuscular disease and chronic respiratory failure (including 19 with tracheostomy). The tracheostomized patients who could breathe spontaneously were recorded during spontaneous breathing (SB) and with MV, in random order. MEASUREMENTS AND MAIN RESULTS: Breathing-swallowing interactions were investigated by chin electromyography and inductive respiratory plethysmography, using three water-bolus sizes (5, 10, and 15 ml) in random order. In contrast to healthy individuals, neuromuscular patients showed piecemeal deglutition with several swallows over several breathing cycles for each bolus. The percentage of swallows followed by expiration was about 50% in the patients compared with nearly 100% in the control subjects. The number of swallows and total swallowing time per bolus correlated significantly to maximal inspiratory pressure. In the 10 tracheostomized patients who were recorded both in SB and MV, the number of swallows and total swallowing time per bolus were significantly reduced during MV compared with SB. CONCLUSION: Neuromuscular patients showed abnormal breathing-swallowing interactions, which correlated to maximal inspiratory pressure. Moreover, MV improved the swallowing parameters in tracheostomized patients who were able to breathe spontaneously.

Assessing inspiratory muscle strength by sniff nasal inspiratory pressure.

The sniff nasal inspiratory pressure (SNIP) consists in the measurement of pressure through an occluded nostril during sniffs performed through the controlateral nostril. It is an accurate and noninvasive approximation of esophageal pressure swing during sniff maneuvers. However SNIP can underestimate esophageal pressure swing in subjects with nasal obstruction, patients with chronic obstructive pulmonary disease and severe neuromuscular patients. Nevertheless, since SNIP maneuver has predicted normal values, is noninvasive and is easier to perform than maximal inspiratory pressure (MIP) maneuver, it could be considered as the first simple test to use in order to assess inspiratory muscle weakness. In addition, because it is as reproducible as MIP, it can be suitable to follow inspiratory muscle function in chronic neuromuscular patients. Because, of the important limit of agreement between SNIP and MIP, these two methods are not interchangeable but complementary.