IJCS | Volume 32, Nº5, September/October 2019

484 Cerqueira et al. NMES after cardiac surgery Int J Cardiovasc Sci. 2019;32(5):483-489 Original Article known as being prognostic in patients submitted to cardiac surgery at hospital discharge. 6 In this context, neuromuscular electrical stimulation (NMES) seems to be a promising option to intensify the rehabilitation of patients in the immediate postoperative period of cardiac surgery. 7 Previous studies have already shown the positive effects of NMES on the exercise capacity of patients with cardiovascular disorders, 8,9 as well as its safety regarding the hemodynamic and respiratory responses to its use. 10,11 However, studies evaluating the use of NMES immediately after cardiac surgery are lacking, wherein patients are more restricted to the bed and often require vasoactive drugs. The aimof this studywas to evaluate the hemodynamic and respiratory responses of patients to NMES session performed in the immediate postoperative period of cardiac surgery. Material and Methods Study design and population This is a pilot, randomized, parallel, two-arm, controlled trial performed at the cardiac ICU from October 2013 to March 2014. This study was carried out in accordance with the Declaration of Helsinki of 1975 (revised in 1983), was approved by the Research Ethics Committee under number 429.256 and all the patients provided their written consent. This studywas submitted to the Brazilian Registry of Clinical Trials ( Registro Brasileiro de Ensaios Clínicos-REBeC ) under number RBR-8vkw87. This studywas initially performed to verify safety and, subsequently, continued research with the creation of a protocol to be used in this population to verify the benefits of NMES. Patients admitted to the ICU within the first 48 h after coronary artery bypass grafting and/or valve replacement were eligible for the study. Those excluded were patients under mechanical ventilation, age younger than 18 years old, body mass index > 40 kg/m 2 , previous neuromuscular diseases, dementia or cognitive disorder, patients with intra-aortic balloon and internal pacemaker, hemodynamic instability, mean arterial pressure < 50 mmHg or > 120 mmHg, dyspnea with oxygen saturation by pulse oximetry (SpO 2 ) < 90%, patients with metallic implants, dermatitis, damaged skin in the area to be stimulated, and sensitivity changes. Randomization Once the patients met the inclusion criteria, they were randomly assigned by an independent participant using the electronic randomization system: http://random.org , in a simple and confidential manner, to the experimental group, who underwent NMES, or the control group, who used sham NMES. Blinding The blinding of the investigators who carried out the study was not performed. However, the patients were blinded to the NMES/sham NMES use. Intervention In the intervention group, the use of NMES occurred in only one instance, during the first 48 h of ICU stay. The surface electrodes were attached to the quadriceps and gastrocnemius muscles bilaterally through the FES current, for 60 min, with a 50-Hz frequency, 200-ms pulse duration, time on of 3 s, and time off of 9 s (NEUROMED 4080 CARCI Brazil). The NMES intensity was adjusted to obtain a visible muscular contraction and, in case of doubt, the contraction was confirmed by palpation of the involved muscles. The patients did not voluntarily perform muscle contraction. Similar to the experimental group, patients in the control group had surface electrodes attached to the same muscle groups for 60 min with the NMES device switched off (sham NMES). Outcome measures The hemodynamic variables (heart rate, HR; systolic blood pressure, SBP; diastolic blood pressure, DBP; and mean blood pressure, MBP) and respiratory variables (respiratory rate, RR and SpO 2 ) were collected before the intervention (baseline), every 15min duringNMES (15, 30, 45, and 60 min) and after 15 min of the recovery period. Regarding the study hemodynamic variables, the HR was verified by a multiparametric monitor (OMNL, OMNIMED, Belo Horizonte, Brazil) connected to the patient through disposable electrodes on the thorax. MBP, DBP and SBP were measured by invasive invasive direct method through radial artery puncture. Regarding the respiratory variables, RR was measured by counting the breaths (inspiration and