Introduction: Central vein catheterization is a common procedure performed on critically ill patients to monitor cardiac filling pressures and to administer medications and parenteral nutrition. In the operative setting, the internal jugular vein is the vessel most often used to place a central venous line because of easy access and because, in the majority of cases, it is excluded from the surgical field. Increasing the cross‑sectional area (CSA) of the internal jugular vein (IJV) improves the success rate of cannulation and decreases complications.

Objectives: To find out the effects of positive end-expiratory pressure on internal jugular vein cross-sectional area in anesthetized Indian adults.

Methods: This is a prospective observational study comprising of 48 patients satisfying the inclusion criteria and undergoing elective surgery under general anesthesia using an endotracheal tube. The following variables like age, sex, ethnic group, weight, associated diseases and its status, were recorded in all patients before induction. Minimum mandatory monitors attached vitals like HR, BP, SpO2, EtCO2, peak pressure and plateau pressure before and after the application of PEEP (PEEP 8). The operating table was placed in a level position in the transverse and longitudinal planes and the patient was positioned with head in neutral position. Five minutes after initiation of mechanical ventilation, USG assessment of the RIJV CSA at the level of the cricoid cartilage using B-mode duplex sonography with a 8- to the 18-MHz linear transducer (VENUE 40 US Wide-band high frequency linear array.) using a standardized technique applying minimal probe pressure to obtain an adequate sonographic image.

 Measurements of transverse and anteroposterior (AP) diameters of the right IJV were obtained at PEEP= 0 (cm H_2O).Then PEEP in increased to  8 cm H2O. After waiting for 2 minutes, the same investigator obtained a second sonographic image of the RIJV at the same location on the neck. And measurements of transverse and anteroposterior (AP) diameters of the right IJV were again obtained.  Depending on the ventilation, the right IJV CSA varies in size; the image is frozen, stored and measured (with the internal calipers in USG) when the largest area is obtained.

Results: There was significant increase in AP diameter, CSA and TD with the application of PEEP 8 cmH2O. The TD increases to a 23.58% and APD increases to 17.44% on application of PEEP. TD increases more with application of PEEP than APD. Thus, the CSA of IJV is increased in patients on application of PEEP 8 cm H2O - (P value 0.0001).

Conclusion: The application of PEEP effectively increases the CSA of the IJV