Causes and mechanism of development
Mendelson's syndrome occurs as a complication during anesthesia delivery (especially during deep mask anesthesia or after the administration of muscle relaxants prior to intubation). The syndrome is based on aspiration — the entry of gastric contents into the trachea and bronchi.
The reflux of gastric contents can occur in two ways:
- Vomiting — an active reflex act.
- Regurgitation — passive outflow of contents due to relaxation of muscular sphincters and gastric distension.
The pathogenesis of the syndrome is directly related to the aggressive acidic environment of gastric juice. Upon reaching the vocal cords and tracheal mucosa, the acid triggers an immediate protective reflex — laryngospasm or bronchospasm. As a result, airway patency is sharply impaired, hypoxia rapidly increases, and severe aspiration pneumonia develops.
Clinical presentation
The clinical manifestation of the syndrome is characterized by an acute onset directly at the moment of intubation, induction of anesthesia, or awakening.
Main symptoms:
- Bronchospasm (diffuse breathing difficulties, wheezing).
- Cyanosis (bluish discoloration of the skin due to oxygen deficiency).
- Tachycardia (rapid heart rate as a compensatory response to hypoxia).
Prevention
Prevention of Mendelson's syndrome is a mandatory stage of preparation for any surgery (for example, in cesarean section, where regional spinal or epidural anesthesia is more often chosen rather than general anesthesia to reduce risks).
Preoperative and intraoperative measures:
- Before anesthesia, gastric emptying using a tube is mandatory.
- In patients with peritonitis or intestinal obstruction, the tube is left in place throughout the entire surgery, and the patient is placed in a moderate Trendelenburg position.
- Sellick's maneuver is a key maneuver during induction of anesthesia and intubation. The physician applies backward pressure to the cricoid cartilage, thereby compressing the esophagus and physically blocking the pathway for regurgitation.
- Upon awakening, the patient is positioned horizontally (or in the Trendelenburg position) with the head turned to the side to prevent aspiration in the event of a gag reflex.
Emergency Medicine
If the reflux of gastric contents has nevertheless occurred, every second counts. The tactics depend on the mechanism of entry of the masses into the respiratory tract:
- In case of vomiting: immediate mechanical removal of contents from the oral cavity using a swab or medical suction.
- In case of regurgitation: emergency extraction of acidic contents directly from the trachea and bronchi using a catheter and vacuum suction.
Sellick's maneuver is easy to remember by its initials: Sellick — Squeezing the esophagus (pressure on the cricoid cartilage).
Class and exam questions
How does regurgitation differ from vomiting?
Vomiting is an active expulsion of contents, whereas regurgitation is passive flowing into the respiratory tract due to relaxation of sphincters (e.g., under the action of muscle relaxants) and gastric distension.
Why is gastric juice aspiration so dangerous?
Gastric juice has a strongly acidic reaction. Entering the bronchi, it causes a severe chemical burn, instantaneous bronchospasm, and, as a consequence, severe hypoxia and aspiration pneumonia.
What does Sellick's maneuver entail?
This is backward pressure applied to the cricoid cartilage prior to anesthesia induction or intubation. The cartilage compresses the esophagus, preventing passive reflux of gastric contents.
What else to study on this topic
- Types of anesthesia in obstetrics: spinal, epidural, and endotracheal anesthesia
- Surgical accesses in laparotomy (Pfannenstiel, Joel-Cohen, Misgav Ladach)
- Variants of hysterotomy: lower segment transverse incision and classical (corporal) incision
- Prevention of venous thromboembolism (VTE) intraoperatively
- Antibiotic prophylaxis of infectious complications in surgical interventions
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