Comparison of Conventional and Manometry Measurement Methods in the Evaluation of Perioperative Laryngeal Edema by USG in Patients Undergoing Lumbar Stabilization Surgery

Prone position is the position in which the patient is laid on his/her abdomen, arms are turned to the sides and the head is turned to one side. Prone position is one of the most commonly used positions in different surgical procedures. Lumbar spinal surgeries (lumbar stabilization, lumbar disc herniation, etc.) are some of the types of surgical operations performed in the pron position. While giving pron position, the table and necessary materials are prepared. A thin pillow is placed under the head and the head is turned to one side. The arms are extended to the side or placed under the head. The abdomen is freed by placing a small support at the hip and shoulder level. Make sure that the eyes are closed to avoid eye pressure. In patients with large breasts and abdomen, a thin pillow is placed under the chest. The feet are supported with a pillow under the ankles. With this position under anesthesia, diaphragmatic movements are restricted as the body weight is placed on the abdominal wall, and the increase in intra-abdominal pressure makes venous return difficult. The breasts in women and genital organs in men may remain under pressure. Weight on bony structures and fingers may cause pressure trauma. These effects can be eliminated with a pillow placed at the shoulder and pelvis level and free movement of the abdomen is provided.

Hemodynamic and position-related complications can often be observed in patients operated in the pron position.

Complications related to the position itself include loss of vision, conjunctival redness ischemic orbital compartment syndrome, nerve damage, abdominal compartment syndrome, acute glaucoma, diplopia, pneumocephalus, shoulder dislocation, endotracheal tube obstruction, facial edema, enteral nutrition intolerance, accidental extubation and small bowel obstruction may be observed. Hemodynamic complications include decreased venous return due to increased intra-abdominal pressure and consequently decreased stroke volume, increased sympathetic response, increased heart rate, increased systemic and pulmonary vascular resistance and decreased left ventricular compliance due to increased intrathoracic pressure. Laryngeal edema may be observed due to compression on the face, jaw and neck and also due to compression of the intubation tube cuff on the tracheal wall and may constitute a risk factor for the development of postextubation stridor after extubation. Laryngeal edema may cause sore throat, cough, dysphonia, dysphagia and even reintubation due to narrowed airway in the patient after extubation, which is seen in the definition of postextubation stridor.

One of the drawbacks of this position in patients to be given general anesthesia is the decrease in airway safety. There is a possibility of tube dislodgement, displacement and kinking during and after the patients are turned to pron position. Therefore, patients should be intubated with a spiral tube, the tube location should be verified and fixed, and the tube location should be verified again after turning to the pron position.

The ideal pressure of the cuff of the intubation tube is 25-30 cmH2O when measured with a cuff manometer. The conventional method, which has been the practice for years, i.e. inflating the intubation cuff with a syringe according to the clinician's own practice, may cause edema in the tracheal wall and larynx and even tracheal necrosis after a while if the cuff is inflated too much. It has been demonstrated that if the pressure of the intubation tube cuff exceeds 30 cm H2O, the blood flow in the tracheal mucosa starts to decrease and if it exceeds 50 cm H2O, ischemic damage develops.