Answer:

Elevation of PIPs is one of the signs of intraoperative bronchospasm. One of the most common causes of bronchospasm during surgery is inadequate depth of anesthesia. The patient with asthma has an extremely sensitive tracheobronchial tree. When the level of anesthesia is too light, the patient may develop straining or coughing as a result of the foreign body (endotracheal tube) in the trachea and then bronchospasm. Therefore, during surgery, the initial treatment of bronchospasm is to increase FIO₂ and deepen anesthesia while investigating other potential causes of bronchospasm (see section C.12).

First, increase the FIO₂ and bag ventilate in order to manually assess pulmonary compliance. Check the anesthesia circuit and the endotracheal tube for kinking and any other visible obstruction. Auscultate the lungs to assess for wheezing. Bilaterally diminished or absent breath sounds can be an ominous sign suggesting critically low airflow, which can occur during severe bronchospasm or a mechanical obstruction of the tube. Unilaterally decreased breath sounds may indicate a main-stemmed endotracheal tube or, rarely, a pneumothorax. Once bronchospasm is confirmed, prior to deepening anesthesia, take a blood pressure. If normal or high, deepen anesthesia by increasing the concentration of inhalation agents, such as sevoflurane or isoflurane, which are direct bronchodilators, or administer an incremental dose of propofol. This has the advantage of deepening anesthesia without relying on alveolar ventilation (which is decreased during bronchospasm) for administration. Likewise, in a patient with a low to normal blood pressure, an incremental dose of ketamine both deepens anesthesia and bronchodilates.

Second, relieve mechanical stimulation. Pass a catheter through the endotracheal tube to suction secretions and determine whether there is an obstruction or kinking of the tube. Occasionally, the endotracheal tube slips down and stimulates the carina of the trachea, causing severe bronchospasm during light anesthesia. The cuff of the endotracheal tube can be deflated, the tube moved back 1 to 2 cm, and the cuff reinflated. Surgical stimulation, such as traction on the mesentery, intestine, or stomach, should be stopped temporarily because it stimulates a vagal reflex and can cause bronchospasm.

Third, start medical intervention if the previously mentioned treatment does not break the bronchospasm or anesthesia cannot be deepened secondary to hypotension. The cornerstone of the treatment of intraoperative bronchospasm is inhalation of ₂-agonists such as albuterol, which induce further bronchodilation even in the presence of adequate inhalational anesthesia. Because of rain-out in the endotracheal tube, a large dose (8 to 10 puffs) should be given to achieve adequate therapeutic levels. If bronchospasm continues despite optimal bronchodilation therapy, high-dose intravenous corticosteroids are indicated (see sections B.16) and B.17). Epinephrine 5 to 10 µg can be given intravenously, but caution should be taken as it can exacerbate tachycardia and tachyarrhythmias. Alternatively, a continuous infusion of epinephrine 0.5 to 2 µg per minute in adults can provide maintenance bronchodilation with fewer adverse effects.