**Abstract**

Pregnant women undergo non-obstetric surgeries as well as cesarean operations. Airway management can be complicated due to physiological changes which occur in the respiratory system of labors. The most common causes of pregnancy-specific hypoxic respiratory failure are eclampsia, preeclampsia, and pulmonary edema that develops secondary to tocolytics. Approximately 10–15% of pregnant women undergo emergency cesarean section. Regional anesthesia is a preferred technique worldwide most commonly, and general anesthesia is applied with rapid sequence induction for the rest of the patients. Difficult Airway Society Master Algorithm for Obstetric Patients is a useful method to manage the airway in labors.

**Keywords:** airway management, respiratory failure, tracheal intubation, pregnancy, labor

## **1. Introduction**

#### **1.1 Pregnancy and physiological changes in the airway**

Several physiological changes develop in the systems during pregnancy. Airway management can be complicated due to these changes that occur in the respiratory system (**Table 1**). Capillary dilatation that occurs during pregnancy due to the gestational hormones including progesterone and estrogen. This causes congestion in the nasopharynx, larynx, trachea, and bronchi. On the other hand, as the uterus expands, the diaphragm elevates approximately 4 centimeters. The decrease in the abdominal muscles' tonus and activity allows the diaphragm to take on more respiratory function. The rise of the diaphragm decreases total lung capacity and functional residual capacity. Relaxation in the airway muscles increases the deadspace capacity. Expiratory reserve and residual volume are reduced. Increased alveolar ventilation and decreased functional residual capacity (FRC) increase the maternal uptake and elimination of inhalation anesthetics. However, decreased FRC and increased metabolic rate predispose to apnea or hypoxemia during hypoventilation periods which can precipitated by airway obstruction and prolonged tracheal intubation attempts.

The changing position of the stomach during pregnancy shifts the intraabdominal segment of the esophagus towards the thorax in many pregnant women. This leads to a decrease in the tone of the lower esophageal high pressure area, which normally prevents reflux of stomach contents. Hence, pulmonary aspiration risk occurs. The risk is higher during anesthesia induction and tracheal intubation. Therefore, rapid sequence induction is recommended.


**Table 1.**

*Changes in lung volume and capacity during pregnancy.*
