Does Transcutaneous Phrenic Nerve Stimulation Prevent Diaphragm Atrophy?

In our study, investigator will investigate the effects of early and late trancutaneous phrenic nerve cytimulation on the prevention of diaphragm atrophy in invasive mechanical ventilation patients (>72 hours MV requirement).

Material and Methods of the Study Our study was planned as prospective, single-center, observational. As a result of the power analysis investigator performed for our study, the minimum sample size was calculated as 40 people for each group and 80 people in total with a 90% confidence interval.

Our study will be conducted as specified in the 1995 Declaration of Helsinki

The patients admitted to the Intensive Care Unit of the Anesthesia and Reanimation Clinic of the University of Health Sciences Bakırköy Dr. Sadi Konuk Training and Research Hospital Anesthesia and Reanimation Clinic Intensive Care Unit between February 1, 2024 and February 1, 2025, the effects of early and late transcutaneous phrenic nerve cytimulation on the diaphragm, diaphragmatic ultrasound and the patient's data registered in the Metavision /QlinICU Clinical Decision Support Software System will be obtained by Structured Query Language (SQL) queries. Vital parameters, hemodynamic, ventilator parameters, laboratory and demographic data will be extracted from the data pool.

Demographic data, biochemical parameters, comorbidities, indications for intubation, duration of invasive mechanical ventilation, respiratory rate, saturation, tidal volume, compliance, FiO2, Peep, above Peep, weaning criteria, peak heart rate, systolic \& diastolic blood pressure, Mean arterial pressure, nutritional assessment, balance status, sedation status, length of ICU and hospital stay, and SOFA, APACHI II, Charlson comorbidity Index (CCI) and Ramsey sedation scores will be extracted from the electronic data system to homogenize the groups.

Patients will be divided into two groups according to early and late transcutaneous electrical diaphragmatic stimulation (TEDS). Group 1 patients with early TEDS will start TEDS at T1 and continue for 5 days. Group 2 patients receiving late TEDS will start TEDS at T2 and continue for 5 days.

Patients receiving invasive mechanical ventilation will receive transcutaneous electrical diaphragmatic stimulation (TEDS) for 30 minutes at 8-hour intervals for 5 days, starting immediately after intubation (0.hour) and 48 hours later. During each session, round electrodes will be placed in the parasternal region, near the xiphoid process, and in the sixth and seventh intercostal spaces in line with the mid-axillary line. TEDS will be performed using a commercial stimulator (Longest MStim Reha LGT_231 portable Electro-Stimulation Therapy Device/China) that applies electrical waves with a frequency of 60Hz, a pulse width of 300 μs and a strength of 30 milliamps. Each stimulation will be applied for 30 seconds: 5 seconds rise time, 5 seconds stimulation time, 5 seconds descent time, 15 seconds listening time. Each session will last 30 minutes and will be performed three times a day. 60 stimulations per session and 180 stimulations per day will be applied to the patient. Stimulation will not be applied when patients are under curare, in pron position, hemodynamically unstable despite catecholamines and agitated (Ramsay sedation score 1/6). The cycles would not be fully synchronized with inspiration as the patients would be ventilated in controlled and pressure support modes.

Patients will undergo diaphragm evaluation with ultrasonography at certain time intervals.

T1: intubation +4h T2: 48.hour+ 4h T3: day 5+4h US-guided diaphragm measurements will be performed in the semi-recumbent position. For evaluation of diaphragm thickness parameters, the diaphragm will be visualized by placing the 7 MHz transducer in the apposition zone perpendicular to the chest wall, in the eighth or ninth intercostal space, between the anterior axillary and midaxillary lines. The diaphragm will be visualized as a structure consisting of two echoic lines (diaphragmatic pleura and peritoneal membrane) and a hypoechoic structure between them (the muscle itself). During quiet tidal breathing, several images of the diaphragm will be taken, at least three at the point of inspiration and at least three at the end of expiration. In each B-mode image, the diaphragm thickness (Tdi) will be measured from the center of the pleural line to the center of the peritoneal line. These three measurements will be averaged and then the diaphragm thickness fraction (DTF) will be calculated as a percentage using the following formula: (End-inspiratory thickness - End-expiratory thickness)/ End-expiratory thickness. To assess the movement of the diaphragm, the 3.5 MHz probe will be placed in the mid-clavicular line below the right subcostal border and moved until the posterior third of the right diaphragm is better visualized. During tidal breathing, M-mode will be used to visualize diaphragm movement along a selected line perpendicular to the diaphragm.

Transcutaneous electrical diaphragm stimulation for both groups will be used in our daily practice.

Patients will be scheduled at the frequency and in the way of application that investigators routinely apply and the routine will not be deviated from.

Statistical Method

GraphPad Prism (v 5.01) program will be used for statistical analysis of the findings obtained in the study. Homogeneity of the variables will be determined by Shapiro-Wilk normality test. Pairwise comparisons of the groups' parameters and demographic data will be compared by Mann Whitney U test, and median and interquartile range (IQR) values will be used in statistical representation. Frequency distribution and percentage values of categorical variables such as gender and intensive care mortality will be compared with the Chi-square test. Within-group repeated measures will be compared by Wilcoxon test for pairwise comparisons and repeated MANOVA for multiple comparisons of more than two parameters. Benforini tests will be used to determine whether there is a statistical difference between the variances. For the statistical representation of the Repeated MANOVA method results, the difference between means and the standard deviation values of the differences will be used. Among the statistical values, p < 0.05 will be considered significant. In the power analysis performed to determine the sample size, the number of patients required to be in each group for the power of the study to be above 80% was calculated as 40. Thus, the number of patients to be included in the study for both groups was calculated as 80.