Airway Pressure and Respiratory Mechanics Variability with Different Body Positions in Mechanically Ventilated Critical Care Patients: A Prospective Comparative Clinical Study
Authors: Elzohry Alaa Ali M. 
Published: May 2021

Aim: This prospective comparative study aimed to investigate the effect of various body positions on changes of respiratory parameters mostly; the TV, oxygen saturation, airway pressure, and endotracheal tube cuff pressure in mechanically ventilated critical care patients. Background: Many patients who are admitted to the critical care unit require intubation and invasive mechanical ventilation for many reasons such as major trauma, medical causes, or post-operative major surgeries. Changing a patient’s position in the critical care unit is very important for the following benefits; to break through the routine monotonic delivery of mechanical ventilation, to favor the clearance of respiratory secretions, the prevention of pressure sores and ventilator acquired pneumonia, and finally the improvement in lung volume and oxygenation. Methods: A prospective, comparative study was carried out on 210 patients of both gender, aged between 21-70 years old admitted to ICU due to many reasons. After stabilization of patient condition and connection of monitors’ cables, supine position or semi setting position was chosen and this was documented in the patient’s chart. All patients were sedated to prevent them from breathing against the machine which causes the ETT cuff pressure and mean airway pressure to rise. Fentanyl sedation drug (Loading dose: 1–2 mic/kg/hour infused gradually. Maintenance dose: 1-4 mic/kg/hour) using continuous intravenous infusion typically in combination with Midazolam sedation (0.05-0.2 mg/kg/hour). The following parameters were recorded; tidal volume, mean airway pressure, PO2 /FIO2 , and ETT cuff pressure. Results: Our results show that about (58.1%) were male and (41.9%) were female. Concerning age, their mean was between (40.6 ± 8.9) years. Regarding diagnosis (50.5%) of patients were admitted with major trauma, (31.9%) due to medical causes, and (17.6%) admitted due to major chest and abdominal surgeries. The patient’s mean heart rate was (93.6 ± 7.5) b/m and the Mean Arterial Pressure was (67.7 ± 0.6)°C. Tables the Description, SOP2, Mean airway, and ETT cuff pressure of each body position in the study with the highest SPO2 98% and cuff pressure 19.2+41 in the prone position. The position checklist is illustrated in Table and Figure. The highest TV (520 ml) and PO2 /FIO2 ratio (410) were in prone poison and the lowest was in Lower Fowler position (460 ml and 320) respectively. Regarding outcome and ICU stay which were the best in both semi setting and prone position. Conclusion: Supine position (lying flat) or lateral position do not seem beneficial for critically ill patients in terms of respiratory mechanics. The semi-sitting position (with thorax angulation=30° from the horizontal plane) is associated with improvement of PO2/FIO2 , oxygenation, and tidal volume, and the effects of prone position on respiratory mechanics are very beneficial and this reflected on patient outcome and short ICU length of stay.