**5.1 Fasting recommendations**

Guidelines for preoperative fasting are formulated in order to reduce the risk of aspiration under general anesthesia or procedural sedation. They apply to all patients undergoing elective surgeries or procedures under general anesthesia, regional anesthesia, procedural sedation and monitored anesthesia care (MAC). Aspiration can happen during all the above-mentioned types of anesthesia as the anesthetic and sedative drugs can obtund the protective airway reflexes which can in turn result in aspiration of gastric contents. It is not applicable to patients undergoing minor surgeries or procedures solely under local anesthesia.

2017 American Society of Anesthesiology (ASA) task force fasting recommendations are summarized in the **Table 3**. For certain procedures like intragastric balloon removal or repositioning, fasting time up to 12 h is recommended. (Please refer to other chapter for more details). Other circumstances and comorbidities as listed in 4.1 might necessitate certain modifications in the fasting guidelines.



**Table 3.**

*2017 ASA fasting guidelines recommendations.*

#### **5.2 Pharmacologic therapies**

To increase gastric pH, **Histamine antagonist (H2)** and **proton pump inhibitors (PPIs)** are commonly used. H2 antagonists as Ranitidine, Famotidine, and Cimetidine, act by blocking the H2 receptors of gastric parietal cells inhibiting the stimulatory effect of histamine on gastric acid secretion. **Proton Pump Inhibitors (PPIs)** as Omeprazole, Lansoprazole and Pantoprazole, irreversibly blocking the Hydrogen/Potassium ATPase of parietal cells and prevent the release of hydrochloric acid [22].

The goal for enhanced gastric emptying is achieved by **prokinetics** such as Metoclopramide [23]. It stimulates the motility of upper GI and is used in risk patient to reduce gastric volume such as Gastroesophageal reflux disease (GERD), Diabetic and pregnant patients and in emergency patients who had no time to be NPO. It also has a peripheral and central Dopamine receptor antagonist activity and might reduce the risk of postoperative nausea and vomiting. Oral antacid can be used in patients with risk of regurgitation and aspiration. Antacids work by neutralization of gastric acid content, single dose 15–30 min before surgery will increase PH above 2.5. Sodium Citrate 0.3 M is non-particulate antacid that itself will not cause pulmonary damage if aspirated with the gastric fluid. Antacids increase gastric volume especially in repeated doses, but this side effect is less important than its action on increasing gastric pH. Decrease gastric volume can be achieved by 6 h fasting before surgery, naso-gastric (NG) tube used to aspirate the gastric content before anesthesia or the use of PPI like Omeprazole to inhibit gastric acid secretion.

#### **5.3 Role of preoperative point of care ultrasound**

Ultrasonography has been recommended as a reliable, noninvasive, bedside tool to determine gastric volume and content in the perioperative period based on many studies [24, 25]. A cutoff of antral cross-sectional area of 340 mm<sup>2</sup> correlates with fluid volume gastric contents greater than 0.8 ml/kg, a high risk of aspiration [19]. However, most studies to date deal with validity considerations and propose that bedside ultrasound accurately determines gastric volume rather than contents [26]. Thus, the use point-of-care ultrasonography in the preoperative period as a screening tool has been recently advocated especially in vulnerable population.

#### **5.4 Anesthesia technique for full stomach**

Anesthesia management of patient with full stomach commences from preoperative period through intraoperative and concludes postoperatively.

**113**

*Airway Management in Full Stomach Conditions DOI: http://dx.doi.org/10.5772/intechopen.93591*

A full preoperative history is a critical step for risk assessment. Predisposing factors as Gastroesophageal reflux disease (GERD), esophageal dysmotility, diabetes, bloating and any condition that delay gastric emptying, history of bariatric surgery or any pathological conditions in upper GI could increase risk of volume

Generally, it is recommended to take clear fluid for up to 2 h preoperatively and stop solid food for 6 h before the surgery as per ASA recommendations described in

The meticulous and skillful airway management is the main goals in preventing gastric aspiration into the lungs during general anesthesia. Airway management

Preoxygenation is administered by face mask for 3 minutes of normal tidal volume breathing that will increase oxygen reserve in the functional reserve capacity (FRC) and provide additional safe apnea time. Passive oxygen insufflation by a nasal canula with 10 l/min during laryngoscopy can prolong the apnea time until desaturation in high risk patient of difficult intubation

High frequency nasal canula (HFNC) or trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) with up to 60 l/min oxygen can be used in critically ill patient that have shorter safe apneic time [30]. It was found that THRIVE will not cause gastric distension or increase the risk of regurgitation. Oxygen flow of 70 l/min will generate a nasopharyngeal pressure of 7 cm H2O, with this pressure it is unlikely to cause gastric distension. In a study 80 patient underwent RSI with the use THRIVE for preoxygenation, no patient shows any

3.Use of rapid sequence induction during tracheal intubation (RSII) with effec-

All equipment should be ready for intubation as variable size facemask, different types of laryngoscopes, different sizes of endotracheal tubes, oral and nasal airways, video laryngoscope, supraglottic airway of different sizes, and

No evidence to support routine preoperative gastric emptying to reduce aspiration risk even in emergency cases except patients suspected ileus or

*5.4.1 Preoperative*

regurgitation.

*5.4.1.1 Pre-anesthesia history*

*5.4.1.2 Preoperative fasting*

detail in (**Table 2**) [21].

obstruction [27].

*5.4.2 Intraoperative*

*5.4.1.3 Preemptive nasogastric tube placement*

techniques intraoperatively involve the following:

during airway management [28, 29].

2.Definitive airway device by a cuffed endotracheal tube

sign of regurgitation [31].

tive cricoid pressure application

1.Adequate preoxygenation with 100% oxygen
