Evaluation of changes in Mallampati grading in patients undergoing elective urological procedures in prone and lithotomy positions- A prospective observational study

Intubation often results in airway edema, which can lead to reintubation following planned extubation in the post-anesthesia care unit. In urological procedures like percutaneous nephrolithotomy (PCNL) and ureteroscopic lithotripsy (URSL), the use of irrigation fluids may exacerbate these airway changes. This study aims to assess alterations in Mallampati grading in patients undergoing elective urological procedures, particularly in prone and lithotomy positions.

This prospective observational study was conducted at a tertiary care hospital from May 2021 to September 2021. Sixty patients with ASA I and II classifications scheduled for elective PCNL in the prone position and URSL in the lithotomy position, with 30 patients in each group, were enrolled. We assessed the Modified Mallampati Grading (MPG) before the procedure and at postoperative intervals of 4 h, 8 h, 12 h, 24 h, and 48 h, noting any changes and the time required to return to the baseline. We also recorded the number of irrigation fluids used, intravenous (IV) fluids administered, surgery duration, and estimated blood loss to explore potential associations.

MPG changed by at least one class in 36.6 % of patients in the prone position and 20 % of patients in the lithotomy position. Furthermore, MPG changed by two classes in 20 % of patients in the prone position and 3.3 % of patients in the lithotomy position. The absorption of irrigation fluids was identified as a potential cause of airway edema, with a significant p-value of 0.0001, leading to worsening of the MPG. Fortunately, in most patients, the changes in MPG returned to baseline values within 24 h.

In conclusion, our study confirms that Mallampati grading may experience at least a one-class increase in both prone and lithotomy positions in most patients, and it typically reverts to baseline in about 24 h for most patients. These airway changes should be considered when re-intubating patients in the postoperative period.