Objectives and hypotheses
Are the objectives of the study clearly stated?
Yes. To compare the efficacy of the valsalva manoeuvre with that of Carotid Sinus massage in terminating paroxysmal supraventricular tachycardias in the emergency department.
Is the study design suitable for the objectives
Yes. This was a prospective randomized unblinded clinical trial. Researchers were not blinded to outcomes and patients - possiblity for bias.
Who / what was studied?
126 patients of at least 10 years of age who presented to the emergency department with regular narrow complex tachycardia. A total of 148 instances of SVT were studied. Patients whose ECG revealed obvious atrial flutter, atrial fibrillation or sinus tachycardia were excluded from the study. Those who were in haemodynamically unstable condition were excluded from this study. Patients with contraindications to carotid sinus massage were also excluded.
Was this the right sample to answer the objectives?
Is the study large enough to achieve its objectives? Have sample size estimates been performed?
148 patients were studied. No sample size estimates were given.
Were all subjects accounted for?
Were all appropriate outcomes considered?
Yes. Conversion to sinus rhythm, adverse effects, post-conversion arrhythmias.
Has ethical approval been obtained if appropriate?
the study was approved by the hospital Ethical Committee.
Were the patients randomised between treatments?
Yes. In a prospective randomized unblinded clinical trial.
How was randomisation carried out?
Yes. Patients were randomly assigned to undergo either the valsalva manoeuvre or CSM. Those who had CSM were further randomised to have either right or left CSM. If the tachycardia was not terminated by the first method of vagal manoeuvre, the patient would undergo the alternate method of vagal manoeuvre. This allowed four choices of order of tests:
1. Valsalva M. - Right CSM - Left CSM
2. Valsalva M. - Left CSM - Right CSM
3. Right CSM - Left CSM - Valsalva M.
4. Left CSM - Right CSM - Valsalva M.
Are the outcomes clinically relevant?
Yes. The outcomes show that physical manoeuvres for the termination of narrow complex tachycardias were effective in a total of 41 instances. The difference between them was not statistically significant. However, both remain as first line mannagement of PSVT.
Measurement and observation
Is it clear what was measured, how it was measured and what the outcomes were?
the efficacy in restoring sinus rhythm by CSM and Valsalva Manoeuvre. Valsalva efficacy was measured by blowing into a mouthpiece connected to a 6-inch tube to a sphygomanometer. The patients were required to reach an airway pressure of 40 mmHg and sustain for 30 seconds or more while supervised by one of the attending clinicians. Carotid sinus massage was performed by the attending emergency physician or resident under supervision of the emergency physician. The outcomes were termination of tachycardia, relapse into tachycardia post conversion and side-effects.
Are the measurements valid?
yes. Patients in whom rhythm conversion was achieved by a vagal manoeuvre were observed in the emergency department with ECG monitoring for two hours. If there was no recurrence, patient was discharged and reviewd in a week.
Are the measurements reliable?
Yes. Measurements were done throughout a two hour period.
Are the measurements reproducible?
Yes. Common ECG
Were the patients and the investigators blinded?
Patients and investigators were not blinded.
Presentation of results
Are the basic data adequately described?
Yes. The study reported the number of subjects which were investigated and how they were obtained. The basic characteristics of the subjects were described. Mean and Median for the measurements were given.
Were groups comparable at baseline?
No indication is given about previous therapy with anti-arrhythmics like amiodarone being interrupted before-hand. Apart from this exclusion criteria removed 14 patients from the study for having an arrhythmia other than SVT.
Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
Yes. Results are presented according to the different randomizations performed, in percentages in associated with confidence intervals and statistical significance.
Are the results internally consistent, i.e. do the numbers add up properly?
Were side effects reported?
No side-effects were reported.
Are the data suitable for analysis?
Are the methods appropriate to the data?
Yes. The X2 test was used to compare the sucess rate of Valsalva manoeuvre and CSM at each level of randomization. The x2 test was also used to compare the sex ratio of patients with success achieved with each vagal technique. A p=0.05 was chosen for accepting statistical significance.
Are any statistics correctly performed and interpreted?
Are the results discussed in relation to existing knowledge on the subject and study objectives?
Yes. Discussion section contains comparisons of the results in this study with other studies performed in the past in the same field.
Is the discussion biased?
The authors are enthusiastic in bringing up reasons for the success of the Valsalva manoeuvre and less enthusiastic in explaining the reasons for failure of the carotid sinus massage.
Are the authors' conclusions justified by the data?
What level of evidence has this paper presented? (using CEBM levels)
This was a randomised unblinded clinical trial - CEBM Level 1
Does this paper help me answer my problem?
It confirms both manoeuvre as being efficient in terminating tachycardias in a quarter of the instances studied. It does not differentiate the efficacy of either manoeuvre when compared to each other.
Can any necessary change be implemented in practice?
No. Valsalva manoeuvre is already the preferred manoeuvre due to its simplicity to use and lack of contra-indications.
What aids to implementation exist?
What barriers to implementation exist?