**4. Pregnancy and respiratory failure**

The most common causes of pregnancy-specific hypoxic respiratory failure are eclampsia, preeclampsia, and pulmonary edema that develops secondary to

**183**

**Table 2.**

Stiffness

Restricted mouth opening Obstruction or obesity Distorted anatomy

*Difficult laryngeal mask ventilation markers: RODS.*

m2

*Airway Management during Pregnancy and Labor DOI: http://dx.doi.org/10.5772/intechopen.96476*

tocolytics. Cardiogenic pulmonary edema due to peripartum cardiomyopathy is another cause. Also, placental abruption, chorioamnionitis, obstetric hemorrhage, or endometritis are among emergencies that cause Adult Respiratory Distress Syndrome (ARDS) [1]. On the other hand, non-pregnancy specific causes include aspiration pneumonia, pulmonary embolism, venous air embolism, pneumothorax,

In pregnancy the chest wall compliance is reduced. The functional residual capacity decreases. This lead to rapid oxygen desaturation during airway management. Upper airway edema becomes another problem. Besides, pulmonary aspiration, viral pneumonitis or thromboembolism risk increases in pregnant patients. Pregnancy carries a risk of increased susceptibility of some pulmonary. Pneumonia

Approximately 10–15% of pregnant women undergo emergency cesarean section [2]. Regional anesthesia is preferred worldwide most commonly, and general anesthesia is applied with rapid sequence induction (RSI) for the rest of the patients. Some tests and examinations are required to evaluate the airway before anesthesia applications. The ideal test should be simple, fast, and cost-effective in the preoperative evaluation. Most bedside testa are affected with anatomical and physiological changes of pregnancy [3]. It should also have high sensitivity, high specificity, and positive predictive value. According to the American Society of Anesthesiologists (ASA) difficult intubation guidelines, the difficult airway definition can be described as an experienced anesthesiologist experiencing difficulties in ventilation, tracheal intubation, or both [4]. Difficult laryngoscopy is defined as an experienced anesthesiologist's inability to perform intubation in more than three attempts with a conventional laryngoscope. Difficult mask ventilation is defined as the anesthesiologist's inability to maintain oxygenation without assistance, the inability to increase the peripheral oxygen saturation above 90% despite using 100% oxygen, or the inability to correct improper ventilation findings. Gas leakage from the face mask, decreased chest movements and auscultation findings, dilatation of the stomach with air, hypoxemia, cyanosis, or hypercarbia indicate improper ventilation. One of the most commonly used preoperative evaluation tests is the Modified Mallampati score. Mallampati score of 3 and 4, BMI of >26 kg.

, mandibular protrusion defect, snoring history, abnormal facial anatomy, and high thyromental distance are among the markers of difficult mask ventilation in pregnant women. Obstructive sleep apnea is another marker of difficult mask ventilation. In the preoperative period, difficult laryngeal mask placement can also

Protruding maxillary incisors, receding mandible, short interincisor distance, and increased neck circumference are among other difficult airway markers in pregnant women. Other potential risk factors include obesity, short neck, receding

be evaluated. Components of the shortening of RODS are listed in **Table 2**.

atelectasis, pulmonary contusion, trauma, burns, and sepsis.

is a significant risk factor for maternal morbidity.

**5. Preoperative preparation**

*Airway Management during Pregnancy and Labor DOI: http://dx.doi.org/10.5772/intechopen.96476*

*Special Considerations in Human Airway Management*

**Tidal Volume Increases by 45%** Inspiratory Reserve Volume Increases by 5% Expiratory Reserve Volume Decreases by 25% Residual Volume Decreases by 15%

Total Lung Capacity Decreases by 5% Vital Capacity Does not change Inspiratory Capacity Increases by 15% Functional Capacity Decreases by 20%

**Volume**

**Capacity**

**Table 1.**

**2. Anatomic changes in pregnant women**

*Changes in lung volume and capacity during pregnancy.*

The main changes occur by the consequences of growing uterus. The diaphragm

is placed upwards. Hence, a shortening of the ribcage and an increase in the anteroposterior and right–left planes take place. Expansion from the ligamentous attachment areas of the ribs facilitates adaptation to these anatomical changes. With the effect of the increasing weight in the pregnant, the obscurity of the anatomical signs on the face and the enlargement of the breasts are among the reasons that cause the difficulty of tracheal intubation. As the uterus continues growing during pregnancy, the intraabdominal part of the stomach and esophagus are displaced to the left of the diaphragm. With this physiological change, progesterone and estro-

gen cause a decrease in esophageal lower sphincter pressure.

Four main drugs are used for aspiration prophylaxis:

enzyme system in the parietal cells of stomach.

induction. The fasting period for solids is six to eight hours.

esophageal sphincter tone rises.

**4. Pregnancy and respiratory failure**

**3. Aspiration prophylaxis and fasting in obstetric patients**

1.Sodium citrate: is a non-particulate antacid and increases gastric pH

3.Proton pump inhibitors: Pantoprazole, omeprazole. They block H+

2.H2-antagonists: Famotidine, cimetidine. They block histamine on the gastric

4.Metoclopramide: stimulates upper gastrointestinal motility, and the lower

Clear liquids are recommended up to two hours before general anesthesia

The most common causes of pregnancy-specific hypoxic respiratory failure are eclampsia, preeclampsia, and pulmonary edema that develops secondary to

K+

ATPase

**182**

parietal cells.

tocolytics. Cardiogenic pulmonary edema due to peripartum cardiomyopathy is another cause. Also, placental abruption, chorioamnionitis, obstetric hemorrhage, or endometritis are among emergencies that cause Adult Respiratory Distress Syndrome (ARDS) [1]. On the other hand, non-pregnancy specific causes include aspiration pneumonia, pulmonary embolism, venous air embolism, pneumothorax, atelectasis, pulmonary contusion, trauma, burns, and sepsis.

In pregnancy the chest wall compliance is reduced. The functional residual capacity decreases. This lead to rapid oxygen desaturation during airway management. Upper airway edema becomes another problem. Besides, pulmonary aspiration, viral pneumonitis or thromboembolism risk increases in pregnant patients. Pregnancy carries a risk of increased susceptibility of some pulmonary. Pneumonia is a significant risk factor for maternal morbidity.
