Supplementary table 1: Trial medications received
Nebulised magnesium sulphate / IV magnesium sulphate / Placebo / Total(N=332) / (N=394) / (N=358) / (N=1084)
Total volume of IV infusion (ml)
Mean (s.d.) / 97.2 (14.8) / 96.5 (16.1) / 97.9 (12.7) / 97.1 (14.6)
100 ml / 299 (90%) / 349 (89%) / 320 (89%) / 968 (89%)
90-99.9 ml / 11 (3%) / 18 (5%) / 16 (4%) / 45 (4%)
70-89.9 ml / 8 (2%) / 8 (2%) / 4 (1%) / 20 (2%)
50-69.9 ml / 0 / 2 (1%) / 1 (<1%) / 3 (<1%)
0-49.9 ml / 7 (2%) / 11 (3%) / 6 (2%) / 24 (2%)
Missing / 7 (2%) / 6 (2%) / 11 (3%) / 24 (2%)
Number of nebulisers given
0 / 0 / 0 / 0 / 0
1 / 2 (1%) / 4 (1%) / 0 / 6 (1%)
2 / 5 (2%) / 1 (<1%) / 2 (1%) / 8 (1%)
3 / 323 (98%) / 387 (99%) / 355 (99%) / 1065 (99%)
Missing / 2 / 2 / 1 / 5
Total volume of nebuliser excluding salbutamol (ml)
Mean (s.d.) / 21.0 (4.1) / 21.5 (3.9) / 21.5 (3.6) / 21.3 (3.9)
22.5 / 261 (79%) / 349 (89%) / 307 (86%) / 917 (85%)
20-22.4 / 11 (3%) / 7 (2%) / 8 (2%) / 26 (2%)
15-19.9 / 21 (6%) / 12 (3%) / 18 (5%) / 51 (5%)
7.5-14.9 / 18 (5%) / 9 (2%) / 9 (3%) / 36 (3%)
0-7.4 / 5 (2%) / 9 (2%) / 6 (2%) / 20 (2%)
Missing / 16 (5%) / 8 (2%) / 10 (3%) / 34 (3%)
Supplementary table 2: Concurrent treatments (specifically salbutamol, ipratropium, prednisolone, hydrocortisone and magnesium sulphate)
Nebulised magnesium sulphate / IV magnesium sulphate / Placebo / Total(N=332) / (N=394) / (N=358) / (N=1084)
Used medication 24 hours prior to attendance / 304 (92%) / 370 (94%) / 320 (89%) / 994 (92%)
Salbutamol / 293 (88%) / 350 (89%) / 309 (86%) / 952 (88%)
Prednisolone / 115 (35%) / 140 (36%) / 106 (30%) / 361 (33%)
Ipratropium / 42 (13%) / 58 (15%) / 47 (13%) / 147 (14%)
Given medication in ambulance or emergency department pre-randomisation / 325 (98%) / 375 (95%) / 344 (96%) / 1044 (96%)
Salbutamol / 320 (96%) / 367 (93%) / 338 (94%) / 1025 (95%)
Ipratropium / 241 (73%) / 279 (71%) / 259 (72%) / 779 (72%)
Prednisolone / 126 (38%) / 154 (39%) / 168 (47%) / 448 (41%)
Hydrocortisone / 71 (21%) / 86 (22%) / 69 (19%) / 226 (21%)
Magnesium sulphate (IV) / 0 / 0 / 3 (1%) / 3 (<1%)
Given medication 0-4h post-randomisation / 180 (54%) / 195 (49%) / 182 (51%) / 557 (51%)
Salbutamol / 107 (32%) / 101 (26%) / 93 (26%) / 301 (28%)
Prednisolone / 64 (19%) / 62 (16%) / 54 (15%) / 180 (17%)
Ipratropium / 59 (18%) / 50 (13%) / 53 (15%) / 162 (15%)
Hydrocortisone / 16 (5%) / 25 (6%) / 19 (5%) / 60 (6%)
Magnesium sulphate (IV) / 21 (6%) / 16 (4%) / 21 (6%) / 58 (5%)
Supplementary table 3: Change in heart rate (beats/min) from baseline to two hours
Nebulised magnesium sulphate / IV magnesium sulphate / Placebo / Overall(N=332) / (N=394) / (N=358) / (N=1084)
Pulse at baseline
No. of obs. / 331 / 394 / 356 / 1081
Mean (s.d.) / 111.1 (19.8) / 112.0 (19.1) / 110.4 (18.9) / 111.2 (19.2)
Change in pulse at 1 hour
No. of obs. / 326 / 387 / 353 / 1066
Mean (s.d.) / -4.4 (13.0) / -5.7 (12.7) / -3.9 (12.3) / -4.7 (12.7)
Change in pulse at 2 hours
No. of obs. / 311 / 379 / 340 / 1030
Mean (s.d.) / -6.3 (15.1) / -6.3 (14.7) / -4.5 (14.4) / -5.7 (14.7)
Comparisons / Mean difference (95% confidence interval) / p-value
Active v placebo / -1.8 (-3.7,0.1) / 0.067
IV v nebuliser / -0.1 (-2.3,2.1) / 0.940
IV v placebo / -1.8 (-4.0,0.3) / 0.096
Nebuliser v placebo / -1.8 (-4.0,0.5) / 0.130
Supplementary table 4: Change in respiratory rate (breaths/min) from baseline to two hours
Nebulised magnesium sulphate / IV magnesium sulphate / Placebo / Overall(N=332) / (N=394) / (N=358) / (N=1084)
Respiratory rate at baseline
No. of obs. / 330 / 392 / 356 / 1078
Mean (s.d.) / 25.7 (7.2) / 25.4 (6.4) / 25.2 (6.3) / 25.4 (6.6)
Change in respiratory rate at 1 hour
No. of obs. / 323 / 381 / 350 / 1054
Mean (s.d.) / -3.1 (5.9) / -3.4 (5.6) / -3.3 (5.4) / -3.3 (5.6)
Change in respiratory rate at 2 hours
No. of obs. / 307 / 374 / 336 / 1017
Mean (s.d.) / -4.3 (7.0) / -4.8 (5.9) / -4.2 (6.3) / -4.5 (6.4)
Comparisons / Mean difference (95% confidence interval) / p-value
Active v placebo / -0.5 (-1.3,0.4) / 0.264
IV v nebuliser / -0.4 (-1.4,0.5) / 0.396
IV v placebo / -0.7 (-1.6,0.3) / 0.154
Nebuliser v placebo / -0.3 (-1.3,0.7) / 0.594
Supplementary table 5: Change in systolic blood pressure (mmHg) from baseline to two hours
Nebulised magnesium sulphate / IV magnesium sulphate / Placebo / Overall(N=332) / (N=394) / (N=358) / (N=1084)
Systolic BP at baseline
No. of obs. / 330 / 392 / 356 / 1078
Mean (s.d.) / 132.5 (20.4) / 133.1 (20.6) / 130.6 (19.7) / 132.1 (20.2)
Change in systolic BP at 1 hour
No. of obs. / 322 / 381 / 351 / 1054
Mean (s.d.) / -4.5 (17.8) / -7.8 (19.4) / -4.2 (18.1) / -5.6 (18.6)
Change in systolic BP at 2 hours
No. of obs. / 309 / 371 / 338 / 1018
Mean (s.d.) / -5.6 (19.9) / -7.7 (18.2) / -6.1 (19.5) / -6.5 (19.2)
Comparisons / Mean difference (95% confidence interval) / p-value
Active v placebo / -0.6 (-3.1,2.0) / 0.664
IV v nebuliser / -1.8 (-4.7,1.1) / 0.214
IV v placebo / -1.5 (-4.3,1.4) / 0.308
Nebuliser v placebo / 0.4 (-2.6,3.3) / 0.810
Supplementary table 6: Change in diastolic blood pressure (mmHg) from baseline to two hours
Nebulised magnesium sulphate / IV magnesium sulphate / Placebo / Overall(N=332) / (N=394) / (N=358) / (N=1084)
Diastolic BP at baseline
No. of obs. / 330 / 391 / 356 / 1077
Mean (s.d.) / 76.3 (15.5) / 75.7 (14.8) / 75.0 (15.1) / 75.6 (15.1)
Change in diastolic BP at 1 hour
No. of obs. / 322 / 380 / 351 / 1053
Mean (s.d.) / -3.4 (14.1) / -6.3 (13.8) / -4.2 (13.6) / -4.7 (13.9)
Change in diastolic BP at 2 hours
No. of obs. / 309 / 369 / 337 / 1015
Mean (s.d.) / -5.8 (14.4) / -7.5 (14.9) / -5.4 (14.6) / -6.3 (14.7)
Comparisons / Mean difference (95% confidence interval) / p-value
Active v placebo / -1.1 (-3.0,0.8) / 0.248
IV v nebuliser / -1.6 (-3.8,0.6) / 0.151
IV v placebo / -1.9 (-4.1,0.2) / 0.080
Nebuliser v placebo / -0.3 (-2.6,1.9) / 0.782
Supplementary table 7: Analysis of peripheral oxygen saturation
(N=332) / (N=394) / (N=358) / (N=1084)
Mode of delivery at baseline
On oxygen / 256 (77%) / 294 (75%) / 259 (72%) / 809 (75%)
On air / 75 (23%) / 99 (25%) / 95 (27%) / 269 (25%)
Not recorded / 1 (<1%) / 1 (<1%) / 4 (1%) / 6 (1%)
Mode of delivery at 1 hour
On oxygen / 285 (86%) / 338 (86%) / 299 (84%) / 922 (85%)
On air / 39 (12%) / 45 (11%) / 51 (14%) / 135 (12%)
Not recorded / 8 (2%) / 11 (3%) / 8 (2%) / 27 (2%)
Mode of delivery at 2 hours
On oxygen / 213 (64%) / 224 (57%) / 199 (56%) / 636 (59%)
On air / 99 (30%) / 154 (39%) / 138 (39%) / 391 (36%)
Not recorded / 20 (6%) / 16 (4%) / 21 (6%) / 57 (5%)
Patients on oxygen
Oxygen saturation at baseline
No. of obs. / 256 / 294 / 259 / 809
Mean (s.d.) / 97.8 (2.1) / 97.9 (2.3) / 98.0 (2.2) / 97.9 (2.2)
Change in oxygen saturation at 1 hour
No. of obs. / 235 / 266 / 234 / 735
Mean (s.d.) / 0.3 (2.0) / 0.3 (2.0) / 0.3 (1.9) / 0.3 (2.0)
Change in oxygen saturation at 2 hours
No. of obs. / 176 / 181 / 164 / 521
Mean (s.d.) / -0.0 (2.3) / -0.1 (2.3) / -0.2 (2.1) / -0.1 (2.2)
Patients on air
Oxygen saturation at baseline
No. of obs. / 75 / 99 / 95 / 269
Mean (s.d.) / 96.3 (2.6) / 95.9 (2.5) / 95.9 (2.6) / 96.0 (2.6)
Change in oxygen saturation at 1 hour
No. of obs. / 24 / 25 / 30 / 79
Mean (s.d.) / 0.0 (2.0) / 1.0 (2.1) / 1.5 (2.6) / 0.9 (2.3)
Change in oxygen saturation at 2 hours
No. of obs. / 34 / 52 / 56 / 142
Mean (s.d.) / -0.0 (2.6) / -0.1 (2.4) / 0.5 (2.6) / 0.2 (2.5)
Supplementary table 8: Change in inspired oxygen flow rate (L/min) from baseline to two hours
Nebulised magnesium sulphate / IV magnesium sulphate / Placebo / Overall(N=332) / (N=394) / (N=358) / (N=1084)
O2 flow at baseline
No. of obs. / 324 / 387 / 344 / 1055
Mean (s.d.) / 5.1 (3.5) / 5.3 (4.0) / 4.8 (3.6) / 5.1 (3.7)
Change in O2 flow at 1 hour
No. of obs. / 312 / 372 / 331 / 1015
Mean (s.d.) / 0.5 (3.4) / 0.4 (3.9) / 0.5 (3.7) / 0.5 (3.7)
Change in O2 flow at 2 hours
No. of obs. / 299 / 361 / 320 / 980
Mean (s.d.) / -0.7 (4.3) / -1.6 (4.8) / -1.3 (4.2) / -1.2 (4.5)
Comparisons / Mean difference (95% confidence interval) / p-value
Active v placebo / 0.0 (-0.6,0.6) / 0.942
IV v nebuliser / -0.9 (-1.6,-0.2) / 0.008
IV v placebo / -0.4 (-1.1,0.2) / 0.196
Nebuliser v placebo / 0.5 (-0.2,1.2) / 0.173
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