Respiratory and gastrointestinal complications
Respiratory disorders are frequently associated with the aspiration of gastric contents into the respiratory tract. This occurs either as vomiting (due to the effect of anesthetic drugs on the vomiting center or the underlying disease) or regurgitation — passive backflow resulting from sphincter relaxation and gastric distension during deep mask anesthesia or the administration of muscle relaxants.
The entry of acidic contents onto the vocal cords causes laryngospasm or bronchospasm, leading to impaired respiration and hypoxia. Clinically, this manifests as cyanosis, tachycardia, and bronchospasm, resulting in Mendelson's syndrome, which is fraught with severe aspiration pneumonia and high mortality.
For prevention, the stomach is preliminarily emptied using a gastric tube. In patients with peritonitis or intestinal obstruction, the tube is left in place until the end of surgery, and the patient is placed in a moderate Trendelenburg position. Immediately before intubation, Sellick's maneuver is performed — pressure is applied to the cricoid cartilage to compress the esophagus.
In addition to aspiration, purely mechanical breathing problems may occur:
- Airway obstruction: tongue fall-back (typical for the surgical stage of anesthesia III$_3$, corrected by advancing the mandible) or foreign bodies (removable dentures).
- Intubation complications: dental trauma caused by the laryngoscope blade, vocal cord damage, accidental intubation of the esophagus or the right bronchus, as well as kinking and accidental dislodgement (extubation) of the tube.
- Technical malfunctions: loss of circuit integrity or ventilator failure.
Circulatory complications
The cardiovascular system suffers due to the direct action of anesthetics or inadequate ventilation.
1. Arterial hypotension. It occurs during the induction of anesthesia due to the depressant effect of drugs on the heart and vasomotor center (especially common when using halothane). If the patient has a pre-existing decrease in circulating blood volume (CBV), blood pressure drops even with the correct dosage. Prevention consists of restoring CBV prior to surgery and timely transfusion of blood substitutes in case of blood loss.
2. Cardiac arrhythmias. Extrasystole, ventricular tachycardia, or ventricular fibrillation may develop. Main causes: hypoxia and hypercapnia (e.g., during prolonged intubation), overdose of halothane or barbiturates, as well as the administration of epinephrine against the background of halothane anesthesia. Treatment boils down to eliminating hypoxia, reducing the anesthetic dose, and administering antiarrhythmics (quinine-group drugs).
3. Cardiac arrest (syncope). It develops due to misjudgment of the patient's condition, errors in conducting anesthesia, deep hypoxia, and hypercapnia. It requires immediate cardiopulmonary resuscitation.
Neurological complications and thermoregulation disorders
Interference with CNS function and prolonged immobilization of the patient on the operating table can lead to specific complications.
Hypothermia and postanesthetic shivering In the operating room, the patient loses heat, and anesthetic drugs suppress the central mechanisms of thermoregulation. As a result, body temperature drops moderately. After waking up (especially after halothane), the body tries to warm up by accelerating metabolism, which manifests as severe shivering. Prevention: maintaining the operating room temperature at 21–22 °C, covering the patient, using warmed infusion solutions and humidified warm breathing mixtures.
Cerebral edema A severe condition caused by prolonged and deep cerebral hypoxia. Treatment is initiated immediately: hyperventilation, dehydration therapy, and local head cooling (craniocerebral hypothermia) are performed.
Peripheral nerve injuries A characteristic feature of this complication is its delayed onset (24 hours or more after surgery). The nerves of the extremities and the brachial plexus are usually affected. The main cause lies in improper patient positioning, which causes severe stretching of the nerve trunks. Risk factors: arm abduction greater than 90°, placing the arm behind the head, rigid fixation to the table frame, or placing the legs on supports without soft padding. Such pareses are treated by a neurologist and a physiotherapist.
Briefly: answers to topical questions
What specific drugs are used to manage intraoperative arrhythmias?
Sources indicate that antiarrhythmic agents, in particular quinine-group drugs, are used for rhythm disorders. Lidocaine is used when defibrillation is ineffective or arrhythmia continuously recurs, to treat ventricular fibrillation and prevent recurrences of ventricular tachycardia/ventricular fibrillation; it is recommended if amiodarone is unavailable. In the acute period of myocardial infarction, lidocaine is used to treat ventricular arrhythmias.
What drugs are used for dehydration therapy in postoperative cerebral edema?
Diuretics and glucocorticosteroids are used for dehydration therapy to treat cerebral edema.
The following drugs are used in clinical practice:
- Furosemide — a loop diuretic used for additional reduction of intracranial pressure.
- Mannitol — an osmotic diuretic that promotes the removal of excess fluid from tissues.
- Urea — used as part of complex dehydration therapy.
- Dexamethasone or prednisolone — glucocorticosteroids prescribed for the management and prevention of brain edema.
What stages and levels of anesthesia are distinguished according to Guedel's classification?
According to Guedel's classification, four successive stages of ether anesthesia are distinguished, reflecting changes in consciousness, respiration, and circulation.
- Stage I — Analgesia.
- Stage II — Excitement.
- Stage III — Surgical (tolerant) stage. It is further subdivided into four depth levels: III-1, III-2, III-3, and III-4.
- Stage IV — Awakening.
If the anesthetic dosage is exceeded, an overdose may occur, characterized by a pale-cyanotic skin color and widely open eyelids.
Class and exam questions
How does regurgitation differ from vomiting during anesthesia?
Vomiting is an active reflex process caused by stimulation of the vomiting center or disease. Regurgitation is the passive backflow of gastric contents into the respiratory tract due to sphincter relaxation and gastric distension (often against the background of muscle relaxants).
Why does a patient experience shivering during or after anesthesia?
During anesthesia, body temperature drops moderately due to the cool operating room environment and the suppression of thermoregulation by drugs (most commonly halothane). Upon awakening, the body compensates for heat loss by increasing metabolism and causing shivering.
When do symptoms of peripheral nerve injury appear after surgery?
They are not noticeable immediately and manifest with a delay — usually 24 hours or more after surgery. The main mechanism of their development is nerve stretching due to improper positioning on the table.
What else to study on this topic
- Technique and anatomical landmarks for performing Sellick's maneuver
- Errors in direct laryngoscopy and criteria for the correct position of the endotracheal tube
- Mechanisms of hypoxia and hypercapnia development during mechanical ventilation disorders
- Emergency care algorithm for Mendelson's syndrome
- Principles of craniocerebral hypothermia in cerebral edema
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