Chapter 35

A 50-year-old obese man (120 kg, 173 cm, BMI 40 kg·m−2) was scheduled for lumbar spine instrumentation. Preoperative airway examination revealed no obvious indicators of difficult laryngoscopic intubation apart from the fact that he had a beard. Following induction of anesthesia with fentanyl, propofol, and rocuronium, a Cormack/Lehane Grade 2 laryngoscopic view was obtained with a #3 Macintosh blade. Laryngoscopic intubation was achieved easily while using backward, upward, and rightward pressure (BURP) externally on the larynx. After securing the endotracheal tube (ETT), the patient was then turned into the prone position for the surgical procedure. Two hours after the start of surgery, and after 1500 mL of blood loss and the administration of 4000 mL of crystalloid, a leak in the ventilation system was identified.

### 35.2.1 What Are Your Concerns When a Patient Is Placed in the Prone Position for a Surgical Procedure?

Proper patient positioning for any medical procedure is an important consideration for a safe and successful outcome. The proper position provides for appropriate surgical access and guards against injury due to pressure points and strain on neurological and musculoskeletal structures. The prone position is most commonly required for surgical procedures on the spine, and for select procedures in neurosurgery, urology, and general surgery. This position is complicated by an increased risk of stretch and pressure injury of nerves, cardiovascular instability, difficulty with ventilation, and problems with providing cardiopulmonary resuscitation as compared with a supine surgical position. Airway considerations for patients placed in the prone position may include difficult access to the airway, migration of the ETT (tip of the ETT moving cephalad or caudad with head extension and flexion, respectively), limited ability to reposition the head and neck for bag-mask-ventilation (BMV), and the potential development of airway edema.

This case represents one of the most challenging situations for airway practitioners: regaining control of the airway promptly with the patient in the prone position. Limited information is currently available in the literature to assist the airway practitioner with critical decision making should they encounter this situation.

### 35.3.1 What Is the Differential Diagnosis of the Ventilation System Leak?

A ventilation system leak is a fairly common occurrence during surgery and is usually easy to manage. However, it is more complex when it occurs in the prone patient due to the unique challenges it presents the airway practitioner and the dangerous or life-threatening situation that may develop for the patient.

In diagnosing and managing this situation, the source of the leak must be promptly determined. This is usually accomplished by inspecting all portions of the anesthesia circuit in an organized and sequential manner. With the prone patient, it is usually easier to start at the anesthesia machine and work your way to the patient. This would include checking flow rates, ventilator/bag volumes, valves, circuit tubing, and connections.

Leaks within the anesthesia machine ...

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