Modified Valsalva Maneuver: A Realist Evaluation

Plain-language summary

Cardiac arrhythmia, specifically paroxysmal supraventricular tachycardia (SVT), accounts for a substantial proportion of emergency medical services resources utilization. Restoring a normal sinus rhythm (reconversion) should be done quickly and effectively. Reconversion requires increasing the atrioventricular node's refractoriness, which can be achieved by vagal maneuvers, pharmacological agents, or electrical cardioversion. The Valsalva Maneuver (VM) is a commonly used non-invasive reconversion method. It increases myocardial refractoriness by increasing intrathoracic pressure for a brief period, thus stimulating baroreceptor activity in the aortic arch and carotid bodies, resulting in increased parasympathetic (vagus nerve) tone. The effectiveness of conventional vagal maneuvers in terminating SVT, when correctly performed, shows a considerable variation ranging from 19.4% to 54.3%. To improve the effectiveness of the Valsalva Maneuver, the Modified Valsalva Maneuver (MVM) was introduced. While the standard VM is performed when the patient is in a sitting position (45°-90°), the modified VM involves having the patient sit up straight and perform a forced expiration for about 15 seconds, after which the patient is brought into a supine position with the legs raised (45°) for another 15 seconds. This modification should increase relaxation, phase venous return, and vagal stimulation. A recent meta-analysis demonstrated a significantly higher success rate for reconversion to sinus rhythm when using the MVM compared to the standard VM in patients with an SVT (Odds Ratio = 4.36; 95 percent c.i. 3.30 to 5.76; P \< .001). More adverse events were reported in the MVM group, although this difference is not significant (Risk Ratio = 1.48; 95 percent c.i. 0.91 to 2.42; P = .11). The available evidence suggests that medication use was lower in the MVM group than in the standard VM group. However, medication use could not be generalized across the different studies. None of the included studies in this review showed a significant difference in length of stay in the emergency department (ED). Hence, the gain of implementing MVM is a higher rate of success with non-invasive reconversion methods. While the available evidence is highly suggestive of supporting the use of the MVM compared to the standard VM in the treatment of adult patients with SVT, implementation seems difficult. Current evaluations, such as the 'gold-standard' randomised controlled trial (RCT) design, rarely adequately or even explicitly address the context-specific drivers behind implementation outcomes and their relationship to the underlying programme theory, making it difficult to interpret their findings in light of other programmes in different settings. As a result, few evaluation strategies are widely accepted as appropriate. The net benefit of interventions and understanding how variable outcomes are achieved remains empirically uncertain. Therefore, it is essential to develop comprehensive, rigorous, and practical methods to evaluate people-centred quality improvement programmes, inform the selection of effective and efficient interventions, and facilitate improvement and scaling-up. In evaluating such complex interventions, the Medical Research Council (MRC) argues for the importance of process evaluation in conjunction with outcome evaluation to account for variability in implementation. The MRC's process evaluation framework guides evaluators to understand the implementation processes (what is implemented and how), mechanisms of intervention (how the delivery of the intervention produces change) and contextual factors that affect implementation and outcomes. Research question This study aimed to evaluate a quality improvement program to improve the non-invasive care for patients with paroxysmal supraventricular tachycardia in the emergency department.

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