The risk of hospitalization and near-fatal and fatal asthma in relation to the perception of dyspnea.

BACKGROUND: A life-threatening asthma attack is still of major concern. One of the main goals in treating patients with asthma is identification of the patients at risk of having these attacks. It has been shown that patients who have a near-fatal asthma attack have a blunted perception of dyspnea (POD). The purpose of this study is to measure the POD in patients with asthma, and to relate POD to life-threatening attacks within a 24-month follow-up period. METHODS: The POD was scored using the Borg scale during breathing against a progressive load at 1-min intervals, in order to achieve mouth pressure up to 30 cm H(2)O, in 113 consecutive asthmatic patients with stable asthma attending an outpatient clinic. All patients were invited to regular follow-up every 3 months for up to 24 months, and all hospitalizations and near-fatal and fatal asthma attacks were recorded. The prebronchodilator morning peak expiratory flow rate (PEFR), daily regular treatment, and beta(2)-agonist consumption were recorded in a diary card for the first 4 weeks. RESULTS: Seventeen patients (15%) had high POD compared to the normal subjects, 67 patients (59%) had POD within the normal range, and 29 patients (26%) had lower-than-normal POD. In the patients with low POD, there was a tendency for higher age, higher female/male ratio, and a longer duration of disease. The rate of severe asthma was higher in the low-POD group than in the normal-POD group, but did not differ from the rate in the high-POD group. The mean daily beta(2)-agonist consumption in the patients with low POD was significantly lower (p < 0.01) than in the patients with high POD, although the mean PEFR was lower in the low-POD group. During the 2 years of follow-up, the patients in the low-POD group had statistically significantly more emergency department (ED) visits, hospitalizations, near-fatal asthma attacks, and deaths compared to the normal-POD and high-POD groups. CONCLUSIONS: Approximately 26% of the referral subjects with asthma had low POD when compared to healthy matched subjects. Patients with low POD had statistically significantly more ED visits, hospitalizations, near-fatal asthma attacks, and deaths during the follow-up period. Reduced POD may predispose patients to a life-threatening attack.

Influence of gender and inspiratory muscle training on the perception of dyspnea in patients with asthma.

BACKGROUND: Men and women respond differently to asthma. PATIENTS AND METHODS: Maximal inspiratory mouth pressure (P(Imax)), beta(2)-agonist consumption, and perception of dyspnea (POD) were measured in 22 women and 22 men with mild persistent-to-moderate asthma. Next, the women were randomized into two groups: those who received inspiratory muscle training and those who received sham training. The training ended when the P(Imax) of the training group was equal to that of the male subjects. POD was then measured once again. RESULTS: Baseline P(Imax) was significantly lower (p < 0.01) while POD and mean daily beta(2)-agonist consumption were significantly higher in the female subjects. P(Imax) reached the level of the male subjects at the end of the 20th week of training. The increase in the P(Imax) was associated with a statistically significant decrease in mean daily beta(2)-agonist use and in POD to a similar level as in male subjects. CONCLUSIONS: POD and mean daily beta(2)-agonist consumption in asthmatic women are significantly higher, and the P(Imax) significantly lower, than that of their male counterparts. When the P(Imax) of female subjects following training is equal to that in male subjects, the differences in POD and mean daily beta(2)-agonist consumption disappear.

Respiratory muscle performance and the Perception of dyspnea in Parkinson's disease.

BACKGROUND: Pulmonary and respiratory muscle function impairment are common in patients with Parkinson's disease (PD). However, dyspnea is not a frequent complaint among these patients, although it is well documented that the intensity of dyspnea is related to the activity and the strength of the respiratory muscles. PATIENTS AND METHODS: We studied pulmonary function, respiratory muscle strength and endurance and the perception of dyspnea (POD) in 20 patients with PD (stage II and III Hoehn and Yahr scale) before and after their first daily L-dopa dose. Respiratory muscle strength was assessed by measuring the maximal inspiratory and expiratory mouth pressures (PImax and PEmax), at residual volume (RV) and total lung capacity (TLC) respectively. The POD was measured while the subject breathed against progressive load and dyspnea was rated using a visual analog scale. RESULTS: Respiratory muscle strength and endurance were decreased and the POD was increased during the off medication period compared to normal subjects. There was a nonsignificant trend to an increase in Plmax, PEmax and endurance after L-dopa intake. The POD of PD patients decreased (p<0.05) following medication, although, it remained increased (p<0.01) as compared to the normal subjects. Even if patients had spirometry data showing a mild restrictive pattern, before medication, both forced vital capacity (FVC) and forced expiratory volume (FEV)1 remained almost identical after L-dopa intake. CONCLUSIONS: Patients with PD have higher POD, compared to normal subjects and this increased perception is attenuated when the patients are on dopaminergic medication. The change in the POD is not related to changes in respiratory muscle performance or pulmonary functions. A central effect or a correction of uncoordinated respiratory movements by L-dopa may contribute to the decrease in POD following L-dopa treatment.