Continuous Nebulization of Albuterol (Salbutamol) in Acute Asthma: RESULTS

Albuterol

Forty-two patients equally divided between the two groups completed the study. Two other patients ini­tially randomized to CN were immediately withdrawn because of technical difficulties resulting in inadequate volume delivered by the nebulizer delivery system. One patient initially in the BN group was withdrawn after a vasovagal episode, considered unlikely to be related to albuterol, while another in the same group refused further therapy and discharged himself from the emergency department.

The demographic characteristics of patients studied are seen in Table 1. Most had been taking inhaled (3- agonists, theophylline, or both.

The baseline FEV1 in the group receiving CN was lower than that in the BN group (1.13 ±0.51 L vs 1.48 ±0.64 L), (p = 0.06).

Table 1 Patient Characteristics

Continuous Nebulization

Bolus Nebulization

No.

21

21

Sex (F/M)

11/10

9/12

Duration of asthma, yr

16

12

(range)

(1.5-35)

(0.2-30)

Previous medication

p-agonist (inhaled)

16

14

(3-agonist (oral)

2

1

Anticholinergic

3

2

Theophylline

17

12

Steroids (inhaled)

3

7

Steroids (oral)

2

3

Initial FEV, (L)

1.13±0.51

1.48 ±0.64f

% predicted*

36± 14

44 ± 13t

Initial FVC (L)

2.16 ±0.72

2.32 ±0.82

% predicted*

53± 14

54± 17

Two subjects in each group were treated concur­rently with intravenous aminophylline and two in each group were given parenteral corticosteroids. At the end of the 2-hour treatment period the CN group had received 10.07 ±0.52 mg of albuterol compared with 10 mg for those assigned to BN.

Figure 1 . FEV1 response

FIGURE 1. FEV, response to inhaled albuterol (salbutamol) admin-istered by bolus nebulization or continuous nebulization. Values in both groups were significantly better than baseline at 90 and 120 minutes (p<0.05). FEV, at 120 minutes was virtually identical in the two groups.

Following treatment with inhaled albuterol the FEV! increased at 30 minutes in the BN group and thereafter improved only minimally (Fig 1). The improvement in the CN group was first seen at 30 minutes and continued to improve progressively throughout the 2-hour study period. At 2 hours the FEV1 was virtually identical in the two groups. Values in both groups were significantly better than baseline at 90 and 120 minutes (p<0.05). The ANOVA with FEV1 as the response variable indicated that the main effect (modes of therapy) was not statistically different (p = 0.398). There was a significant time effect (p<0.001) that confirmed that the increases in FEV, over time were not constant. There was a significant mode of therapy by time interaction (p = 0.024) indi­cating the time course of the effects for BN and CN were not parallel. This interaction is apparent in Figure 1 where the CN response is gradually increas­ing while the BN response seems to have reached its plateau.
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Table 2—Vital Signs During Therapy (Mean±SD)

Technique

Baseline

30 min

60 min

90 min

120 min

Systolic

BN

130 ±20

128 ±15

125 ±14

126 ±16

123 ± 15

pressure,

mm Hg

CN

131 ±14

132 ±12

131 ± 17

127 ±13

131 ±14

Diastolic

BN

83 ±10

81 ± 11

79 ±13

77 ±14

79 ±14

pressure,

mm Hg

CN

84 ± 9

84 ± 10

84 ±8

82 ± 7

82 ±9

Pulse,

BN

90 ±12

96 ± 19t

95 ±21

101± 20+t

96 ± 14

beats/min

CN

93 ±19

88± 14

93 ±14

95 ±16

95 ±14

Respirator)’

BN

24 ±5

23 ±4

22 ± 4

22±4

21 ±5

rate

CN

23 ±7

22 ±6

22 ±7

22 ±5

22 ±5

When FEV, was analyzed as percent predicted essentially the same results were obtained. The initial and final values were 44 ±13 percent and 65 ±20 percent for patients receiving BN, and 36 ± 14 percent and 68 ± 19 percent for those in the CN group (Fig 2).

Figure 2 . FEV1 response

Figure 2. FEV, response expressed as a percent of the predicted value.

There was a slight but statistically significant in­crease in pulse in the BN group at 30 and 90 minutes when compared with CN (Table 2). Furthermore, the  BN group showed a significant increase in pulse at 90 minutes when compared with baseline (Table 2). Otherwise, there were no significant differences in blood pressure or respiratory rate between or within the two groups. Tremor was judged as absent in most individuals and was not different between groups (Table 3). There were no adverse reactions noted and no patient had to be withdrawn from therapy because of a deterioration in respiratory status.

Table 3—Tremor During Therapy

Baseline

30 min

60

min

90 min

120 min

BN

CN

BN

CN

BN

CN

BN

CN

BN CN

Absent

18

20

16

16

15

14

15

12

15 12

Mild

3

1

2

4

5

5

4

4

5 3

Moderate

3

1

1

2

2

4

1 5

Severe

1

– 1

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