Involuntary glottal closure during inspiration in muscle tension dysphonia

Objective/Hypothesis: The purpose of this study was to examine respiratory function in a group of patients with muscle tension dysphonia (MTD) Design: Cross-sectional analytical study. Methods: Participants included 15 people with a diagnosis of MTD referred to speech pathology for management of their voice disorder, fiberoptic evidence of glottal or supraglottic constriction during phonation with or without posterior chink, or bowing combined and deviation in perceptual voice quality. A second group of 15 participants with no history of voice disorder served as healthy controls,. Baseline pulmonary function test measures included forced expiratory volume in the first second (FEV1), FVC, FEF25 to 75, FIF50, FEV1/FVC, ratio and FEF50/FIF50 ratio. Hypertonic saline challenge test measures included FEV1 and FIF50 after provocation, close response slope, and provocation dose. Results: Compared with healthy controls, participants with MTD demonstrated a higher prevalence of glottal constriction during inspiration after provocation with nebulized hypertonic saline as demonstrated by a reduction in FIF50 after the hypertonic saline challenge. There was no significant difference between the MTD and healthy control groups in baseline pulmonary function testing. Participants with MTD demonstrated a higher prevalence than healthy controls of abnormal glottic closure during inspiration similar to paradoxical vocal fold movement (PVFM). This suggests that they either had previously undiagnosed coexisting PVFM or that the condition of MTD could be expanded to include descriptions of aberrant glottic function during respiration. This study enhances the understanding of PVFM and MTD by combining research advances made in the fields of otolaryngology and respiratory medicine.

Design for Inspiration: Children, personal connections and educational technology

The project is working towards building an understanding of the personal interests and experiences of children with the aim of designing appropriate, usable and, most importantly, inspirational educational technology. kidprobe, an adaptation of the technology probe concept, has been used as a lightweight method of gaining contextual information about children's interactions with 'fun' technology. kidprobe has produced design inspiration which focuses primarily on the social and emotional connections children made. The use of kidprobe has generated some important ideas for improving the use of probes with children. It is an important first step in understanding how to effectively adapt probing techniques to inspire the design of technology for children.

The Anglo Cluster: Legacy of the British Empire

The Anglo cluster comprises Australia, Canada, England, Ireland, New Zealand, South Africa (White sample), and the United States of America. These countries are all developed nations, predominantly English speaking, and were all once British colonies. Today, they are amongst the wealthiest countries in the world. The GLOBE results show that the Anglo cluster is characterized by an individualistic performance orientation. Further, although they value gender equality, the Anglo cluster countries tend to be male-dominated in practice. Effective leadership in the Anglo cultures is affected by a combination of charismatic inspiration and a articipative style.

Changes in intra-abdominal pressure during postural and respiratory activation of the human diaphragm

In humans, when the stability of the trunk is challenged in a controlled manner by repetitive movement of a limb, activity of the diaphragm becomes tonic but is also modulated at the frequency of limb movement. In addition, the tonic activity is modulated by respiration. This study investigated the mechanical output of these components of diaphragm activity. Recordings were made of costal diaphragm, abdominal, and erector spinae muscle electromyographic activity; intra-abdominal, intrathoracic, and transdiaphragmatic pressures; and motion of the rib cage, abdomen, and arm. During limb movement the diaphragm and transversus abdominis were tonically active with added phasic modulation at the frequencies of both respiration and limb movement. Activity of the other trunk muscles was not modulated by respiration. Intra-abdominal pressure was increased during the period of limb movement in proportion to the reactive forces from the movement. These results show that coactivation of the diaphragm and abdominal muscles causes a sustained increase in intra-abdominal pressure, whereas inspiration and expiration are controlled by opposing activity of the diaphragm and abdominal muscles to vary the shape of the pressurized abdominal cavity.

Contractions of specific abdominal muscles in postural tasks are affected by respiratory maneuvers

The influence of respiratory activity of the abdominal muscles on their reaction time in a postural task was evaluated. The electromyographic (EMG) onsets of the abdominal muscles and deltoid were evaluated in response to shoulder flexion initiated by a visual stimulus occurring at random throughout the respiratory cycle. Increased activity of the abdominal muscles was produced by inspiratory loading, forced expiration below functional residual capacity, and a static glottis-closed expulsive maneuver. During quiet breathing, the latency between activation of the abdominal muscles and deltoid was not influenced by the respiratory cycle. When respiratory activity of the abdominal muscles increased, the EMG onset of transversus abdominis and internal oblique, relative to deltoid, was significantly earlier for movements beginning in expiration, compared with inspiration [by 97-107 ms (P < 0.01) and 64-90 ms (P < 0.01), respectively]. However, the onset of transversus abdominis EMG was delayed by 31-54 ms (P < 0.01) when movement was performed during a static expulsive effort, compared with quiet respiration. Thus changes occur in early anticipatory contraction of transversus abdominis during respiratory tasks but they cannot be explained simply by existing activation of the motoneuron pool.

Pressure support ventilation with the ProSeal (R) laryngeal mask airway. A comparison of sevoflurane, isoflurane and propofol

Background and objective: There are no data about the influence of anaesthetics on cardiovascular variables during pressure support ventilation of the lungs through the laryngeal mask airway. We compared propofol, sevoflurane and isoflurane for maintenance of anaesthesia with the ProSeal (R) laryngeal mask airway during pressure support ventilation. Methods: Sixty healthy adults undergoing peripheral musculo-skeletal surgery were randomized for maintenance with sevoflurane end-tidal 29%, isoflurane end-tidal 1.1% or propofol 6 mg kg(-1) h(-1) in oxygen 33% and air. Pressure support ventilation comprised positive end-expiratory pressure set at 5 cmH(2)O, and pressure support set 5 cmH(2)O above positive end-expiratory pressure. Pressure support was initiated when inspiration produced a 2 cmH(2)O reduction in airway pressure. A blinded observer recorded cardiorespiratory variables (heart rate, mean blood pressure, oxygen saturation, air-way occlusion pressure, respiratory rate, expired tidal volume, expired minute volume and end-tidal CO2), adverse events and emergence times. Results: Respiratory rate and minute volume were 10-21% lower, and end-tidal CO2 6-11% higher with the propofol group compared with the sevoflurane or isoflurane groups, but otherwise cardiorespiratory variables were similar among groups. No adverse events occurred in any group. Emergence times were longer with the propofol group compared with the sevoflurane or isoflurane groups (10 vs. 7 vs. 7 min). Conclusion: Lung ventilation is less effective and emergence times are longer with propofol than sevoflurane or isoflurane for maintenance of anaesthesia during pressure support ventilation with the ProSeal (R) laryngeal mask airway. However, these differences are small and of doubtful clinical importance.

Reduced inspiratory muscle endurance following successful weaning from prolonged mechanical ventilation

Study objectives: Respiratory muscle weakness and decreased endurance have been demonstrated following mechanical ventilation. However, its relationship to the duration of mechanical ventilation is not known. The aim of this study was to assess respiratory muscle endurance and its relationship to the duration of mechanical ventilation. Design: Prospective study. Setting: Tertiary teaching hospital ICU. Patients: Twenty subjects were recruited for the study who had received mechanical ventilation for a 48 h and had been discharged from the ICU. Measurements: FEV1 FVC, and maximal inspiratory pressure (Pimax) at functional residual capacity were recorded. The Pimax attained following resisted inspiration at 30% of the initial Pimax for 2 min was recorded, and the fatigue resistance index (FRI) [Pimax final/Pimax initial] was calculated. The duration of ICU length of stay (ICULOS), duration of mechanical ventilation (MVD), duration of weaning (WD), and Charlson comorbidities score (CCS) were also recorded. Relationships between fatigue and other parameters were analyzed using the Spearman correlations (p). Results: Subjects were admitted to the ICU for a mean duration of 7.7 days (SD, 3.7 days) and required mechanical ventilation for a mean duration of 4.6 days (SD, 2.5 days). The mean FRI was 0.88 (SD, 0.13), indicating a 12% fall in Pimax, and was negatively correlated with MVD (r = -0.65; p = 0.007). No correlations were found between the FRI and FEV1, FVC, ICULOS, WD, or CCS. Conclusions: Patients who had received mechanical ventilation for > 48 h have reduced inspiratory muscle endurance that worsens with the duration of mechanical ventilation and is present following successful weaning. These data suggest that patients needing prolonged mechanical ventilation are at risk of respiratory muscle fatigue and may benefit from respiratory muscle training.