*4.1.8 Type of anesthesia*

Mainly the aspiration is during general anesthesia; however, 7% of aspiration in ASA closed claims have occurred during regional anesthesia or monitored anesthesia care. 18% of the aspiration that occurred during maintenance of anesthesia was either by facemask, laryngeal mask [12].

#### *4.1.9 Gastric volume*

It was found that when gastric volume (GV) was less than 0.4 ml/kg, the incidence of vomiting was only 6.7%. Once the volume exceeded 0.8 ml/kg, the incidence of vomiting was as high as 44.1%. In supine position, patients with crosssection area (CSA) less than 340 mm2 was considered as fasting. On the contrary, CSA was greater than 340 mm2 indicates GV of greater than 0.8 ml/kg [19].

#### *4.1.10 Determination of critical volume of gastric contents*

A critical volume of gastric contents required to produce severe aspiration pneumonitis has been even more debatable than determining critical PH. In one study, pulmonary injury became independent of pH as the volume of aspirate was increased from 0.5 to 4.0 ml/kg in dogs. Nevertheless, it was generally accepted that the volume of gastric fluid of 0.4 ml/kg places a subject at risk for developing aspiration pneumonitis based on experimental instillation of gastric fluid into the right main stem bronchus of a single Rhesus monkey [20].

However, The ASA Task Force on Preoperative Fasting, despite extensive screening of the current data, has been unable to establish a link between residual gastric volume and pulmonary aspiration [21].

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**Table 2.**

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

**period** are summarized in **Table 2**.

**5.1 Fasting recommendations**

under local anesthesia.

fasting guidelines.

**Fasting time**

**Pharmacologic therapies** • Decrease gastric acidity

**Anesthesia techniques**

Gastrointestinal factors • Enhancing gastric emptying • Decreasing gastric volume

• Minimize the volume of gastric contents • Increasing pH of gastric contents • Reduce gastroesophageal reflex

• Facilitating gastric emptying/drainage

• Maintenance of competent lower esophageal sphincter tone

• Preoperative (History – Optimization of risk factors) • Intraoperative (Preoxygenation + RSI + Cricoid maneuver) • Postoperative and recovery (awake during extubation)

*Summary of aspiration prophylaxis goals in preoperative period.*

**5. Perioperative anesthesia management in full-stomach patients**

Identification of patients who are at risk for pulmonary aspiration is the first step toward minimizing the incidence of perioperative pulmonary aspiration. Two patient risk categories exist: those with a full stomach (i.e., history of ingestion of a meal with less than 6 h fasting time) and those designated as having a full stomach despite a prolonged preoperative fast. **Aspiration prophylaxis goals in preoperative** 

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

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

• Adequate preoperative fasting based on age and food type specific recommendation

*Special Considerations in Human Airway Management*

significantly [16].

*4.1.7.2 Advanced age*

peristalsis [17].

*4.1.7.3 Gastrointestinal disorder*

*4.1.7.4 Specific anesthesia time*

*4.1.8 Type of anesthesia*

*4.1.9 Gastric volume*

either by facemask, laryngeal mask [12].

section area (CSA) less than 340 mm2

volume and pulmonary aspiration [21].

*4.1.10 Determination of critical volume of gastric contents*

CSA was greater than 340 mm2

A1c value of more than 7%, could lead to delayed gastric emptying, by decreasing the frequency of gastric contraction, while the risk score of aspiration increase

Old age is an independent risk factor for delayed gastric emptying, as it is common in elderly patient to have anorexia, dyspepsia and impaired gastric

complications following abdominal surgeries especially bowel resection, colon and rectal surgery, all lead to impaired contractility, motility and gastric emptying [18].

ASA closed claims have identified that aspiration cases were associated with anesthesia induction in 60%, maintenance in 18% and during emergence in 11% and in PACU in 5% anesthesia related claims, indicating that aspiration commonly

Mainly the aspiration is during general anesthesia; however, 7% of aspiration in ASA closed claims have occurred during regional anesthesia or monitored anesthesia care. 18% of the aspiration that occurred during maintenance of anesthesia was

It was found that when gastric volume (GV) was less than 0.4 ml/kg, the incidence of vomiting was only 6.7%. Once the volume exceeded 0.8 ml/kg, the incidence of vomiting was as high as 44.1%. In supine position, patients with cross-

A critical volume of gastric contents required to produce severe aspiration pneumonitis has been even more debatable than determining critical PH. In one study, pulmonary injury became independent of pH as the volume of aspirate was increased from 0.5 to 4.0 ml/kg in dogs. Nevertheless, it was generally accepted that the volume of gastric fluid of 0.4 ml/kg places a subject at risk for developing aspiration pneumonitis based on experimental instillation of gastric

However, The ASA Task Force on Preoperative Fasting, despite extensive screening of the current data, has been unable to establish a link between residual gastric

fluid into the right main stem bronchus of a single Rhesus monkey [20].

was considered as fasting. On the contrary,

indicates GV of greater than 0.8 ml/kg [19].

Functional delayed gastric emptying (FDGE) and Ileus are common

occurs during induction, but the risk is still high even till PACU [12].

**110**
