Neuromuscular Electrical Stimulation(NMES) group received consecutive daily sessions of electrical stimulation at specific points starting on the first day of randomization.The subjects also receive conventional physical therapy, which included gross motor therapy and respiratory therapy twice a day every day during their stay in the ICU.

The subjects only receive conventional physical therapy, which included gross motor therapy and respiratory therapy twice a day every day during their stay in the ICU.

NMES was performed using a portable machine.The negative electrodes were placed in the motor points of the following muscles: chest muscles (pectoralis major muscle fibres) and rectus abdominis muscles bilaterally. A second (positive) electrode was positioned distally to the first, at a site close to the muscle that was being electrically stimulated, totalling 1 channel with 2 electrodes for each muscle . Each NMES session lasted 30 min. The following parameters were used: 50 Hz frequency, pulse duration 300 ms, rise time 1 s, stimulus time (ON) 3 s, decay time 1 s, and relaxation time (OFF) 10 s. Intensity was increased until muscle contraction was visible or could be identified through palpation. In conscious patients, intensity was adjusted according to their tolerance.

DTF shows varied thickness of the diaphragm at end-expiration and end-inspiration. Te maximum and minimum values of each breathing cycle were taken as the end-inspiratory diaphragm thickness (DTei) and the end-expiratory diaphragm thickness (DTee), respectively. DTF was calculated by DTF=(DTei DTee)/DTee 100%. Te values for 3 consecutive respiratory cycles were recorded and the average value was taken as the fnal value

A 10- to 15-MHz linear array transducer was positioned perpendicular to the anterior thorax surface in the longitudinal scan, at the level of the second right intercostal space, approximately 6 to 8 cm lateral to the sternal edge with a window visualizing the second and third ribs. . Using M-mode, the ultrasound beam was perpendicularly directed at the midsection of the muscle, where it is the thinnest at end-expiration. The thickness of the parasternal intercostal muscle was measured on frozen images at end expiration and at peak inspiration.