IJCS | Volume 32, Nº5, September/October 2019

485 Cerqueira et al. NMES after cardiac surgery Int J Cardiovasc Sci. 2019;32(5):483-489 Original Article expiration) for 1 min. SpO 2 was measured with a pulse oximeter placed on the patient’s finger, connected to the multiparametric monitor. Statistical analysis Data are shown as mean and standard deviation and the categorical variables are shown as absolute numbers and percentages. The statistical analyses were performed with the software SPSS version 15.0 (IBMCorp., Armonk, NY, EUA). Data distribution was evaluated by the Shapiro–Wilk test. The analysis of variance for repeated measurements (ANOVA) was used to compare changes in means over the six timepoints (rest, 15, 30, 45, 60 min and 15 min after of the recovery period), corresponding to the intragroup analysis. Two-way repeated measures ANOVA was used to compare means between two groups over the six timepoints, corresponding to the intergroup analysis. The Chi-Square test was used for categorical variables and the t-test for independent samples was used to compare the numerical variables regarding patients’ characteristics between the groups. Values of p < 0.05 indicated statistical significance. Results The study included 30 patients submitted to cardiac surgery, with 15 patients in the experimental group and 15 in the control group, respectively (Figure 1). In the experimental group, the use of NMES occurred in the first 23.13 ± 5.24 h and ,in the control group, 22.20 ± 5.46 h after cardiac surgery. No complications were observed during our protocol, and none of the patients were excluded. The sample characteristics are shown in Table 1. No change was found in the hemodynamic and respiratory variables in the patients submitted to neuromuscular electrostimulation, as well as in the control group patients. In addition, all hemodynamic and respiratory parameters remained within normal limits (Table 2). Discussion The main finding of this study was that an NMES session did not result in any changes in HR, SBP, DBP, MBP, RR, and SpO 2 in patients in the immediate postoperative period of cardiac surgery. In the past, many professionals working with cardiovascular rehabilitation hesitated to prescribe NMES to patients with heart disease, contraindicating electrotherapy due to the risk of cardiac arrhythmia. 3 Additional concerns that could contribute to the non- indication of NMES would be the concern that repeated sustained muscle contractions would elevate total peripheral resistance, resulting in acute elevations in blood pressure and hemodynamic overload, increasing the risk of cardiovascular complications in critically-ill patients. 12 Despite these facts, NMES has been proposed as a promising adjuvant therapy to increase the physical capacity of patients involved in cardiovascular rehabilitation programs, such as patients hospitalized for heart failure, 13 and in patients in the postoperative period of cardiac surgery. 14 Some authors have already investigated hemodynamic responses to the use of NMES in healthy subjects, 15 exercise plus NMES in patients with heart failure, 10 and in patients under critical care. 11 However, only one study investigated the safety of NMES immediately after cardiac surgery. 3 In this study, no patient showed changes in blood pressure and HR that exceeded the safety criteria defined by the study. The mean variation was a maximum of 2.1 mmHg for SBP and 1.7 bpm for HR. 3 In the present study, the majority of the patients used inotropic agents, such as dopamine, dobutamine, noradrenaline, and/or needed vasopressor support to maintain their hemodynamic stability, whichwould lead to extra concerns regarding the cardiovascular system during NMES application. However, no statistical or clinical changes were observed (4.53 bpm for HR; 2.93 mmHg for SBP, 3.27 mmHg for DBP and 1.73 mmHg for MBP). No cardiac arrhythmia was reported either. A previous study found that a session of NMES in critically-ill patients caused an increase in SBP and HR of 6 mmHg and 5 bpm, respectively, although the authors stated that this result was not clinically significant. 16 Another author also found small changes in HR, of approximately 1 bpm, and in SBP and DBP, of approximately 1 mmHg, with no statistical significance when NMES was applied on the femoral quadriceps of critically-ill patients. 17 These borderline increases in BP and HR after the use of NMES in critically-ill subjects are in agreement with the results presented by this study, wherein one can observe similar variations of these variables, including in the control group, with no statistical and clinical difference between the groups.