Pulse methylprednisolone infusion was found to be relatively safe when given over 1 hour or extended up to 6 hours. Our data showed that there is no significant difference in vital signs readings before and after infusion between different infusion rates, while there was a change in blood pressure and heart rate readings before and after the administration of IVMP however, this variation remains within normal range and does not move far from the baseline. Additionally, this variation has not been affected by the infusion rate. The variation in heart rate might be related to individual factors such as stress, the timing of vital sign measuring, and patient activity during the hospital stay. Out of 74 patients, 8 patients developed bradycardia( as defined by heart rate less than 60 beats per minutes9), 2 of them were baseline HR < 60 BPM which increased after IVMP, while the remaining 6 patients developed Bradycardia after receiving IVMP, 5 patients (8%) were in the conventional group and 1 patient (8.3%) was on the extended group, although no significant difference in the incidents of bradycardia between different infusion rate of IVMP.
On the other hand, tachycardia (as defined by a heart rate of more than 100 BPM (8)), was documented in 8 patients (7 patients in conventional group and 1 patient in extended group) out of 74 patients. Seven out of those 8 patients had developed tachycardia at baseline before IVMP was administered on days 1 and 2, while only 1 patient who was in the conventional group developed mild tachycardia after being given IVMP. We believe the tachycardia happened due to individual factors as patients were initially and persistently tachycardiac even before IVMP was given.
As this is a retrospective study, only a limited number of patients completed all vital signs readings during the whole 5 days, in addition, the majority of patients have received only 3 doses of IVMP in hospital and completed the steroid course in outpatient settings, therefore, we performed sub-analysis comparing the mean of heart rate in 2-time points( at baseline and immediately after IVMP) from day1 to day 3, the results illustrated in table A, B.
This sub-analysis interestingly showed a statistically significant increase in the heart rate means in the conventional group immediately after 1st and 2nd doses despite being still in the normal range. This increase in heart rate does not reflect any clinical symptoms, while in the extended infusion group there was a non-statistically significant increase in heart rate before and after IVMP possibly due to the long duration of infusion.
Yong, Kai-Ling et al. (4) found that IVMP led to a significant percentage drop in HR at 60 minutes which is contradictory to our sub-analysis results, this might be explained by the effect of comorbidities and medications of the included subjects, which were excluded in our study as we included only healthy subjects without comorbidities.
Generally, we found there is a mild increase in the mean BP after receiving IVMP but without inducing hypertension, the possible mechanisms are sodium retention, volume expansion (5), and interrupting nitric oxide system. Steroids may also mediate vascular vasoconstrictor sensitivity to catecholamines and other vasoconstrictor hormones systems [4].
Hypokalemia is one of the possible side effects of IVMP which is defined as a serum potassium level less than 3.5 mEq/l. The normal range of serum potassium is 3.5 to 5 mEq/l, out of 46 patients who were potassium level checked before and 24-72 following IVMP administration, only one patient developed mild hypokalemia (3.4 mEq/l). Interestingly, in comparison with baseline, 23 patients (50%) their potassium level had increased within normal range after receiving IVMP, however, it was not statistically significant (P = 0.17, 0.72) in the conventional group and extended group respectively (Table 8).
Table 8. potassium level before and after steroid pulse infusion.
Infusion group
|
Initial potassium level
|
Post infusion potassium level
|
P-value
|
Conventional group N=39
|
4.03+/- 0.26
|
4.1+/-0.3
|
0.17
|
Extended group N=7
|
4.16+/- 0.35
|
4.07+/-0.3
|
0.72
|
Table A. heart rate changing in the conventional group from day 1-3
Days
|
Baseline heart rate
|
Post infusion heart rate
|
P-value
|
Day 1 n=60
|
75.62 ± 10.1
|
79.1±10
|
0.003
|
Day 2 n=54
|
75±10.3
|
79.9±10.3
|
0.013
|
Day 3 n=47
|
75.3±10.4
|
77.2±9.3
|
0.294
|
Table B. heart rate changing in the extended group from day 1-3
Days
|
Baseline heart rate
|
Post infusion heart rate
|
P-value
|
Day 1 n=12
|
81.83± 15.314
|
82.42± 14.016
|
0.808
|
Day 2 n=11
|
81.82± 16.061
|
84.00± 12.058
|
0.563
|
Day 3 n= 9
|
81.33± 17.664
|
77.89± 11.230
|
0.322
|
Our study findings support the suggestion of Kai-Ling Yong El who discouraged regular potassium checking after IVMP administration in relatively well patients with normal potassium at baseline, while restricting its measurement for those patients with other risk factors., such as renal failure or use of medications such as diuretics (4,10).
Strength and limitations
Our study included 688 vital signs (BP, HR) measurements related to 277 infusions administered. The main limitation of our study was the small number of study subjects in the extended group, in addition, there was variability in the length of stay and the frequency of monitoring.