Post-Operative Anesthetic Complications

Synopsis

After successful surgery, the patient enters one of the most potentially hazardous phases of the procedure, namely emergence from anesthesia and the immediate post-operative period. The care team is busy with many tasks at this point, but the main attention should always be on the awakening patient and his or her needs. This chapter will focus on complications that may arise at that time, together with their prevention and management.

Introduction

A complication may be defined as an unanticipated problem that arises after, and is a result of, a procedure, treatment, or illness. In many cases, post-operative complications occurring in the post-anesthesia care unit (PACU) are not caused entirely by anesthesia. Often there are multiple factors that lead to the complication. These may be related to the patient, the surgery, and the anesthesia. As an example, laryngospasm after cleft palate repair may occur in the PACU, just as it can in the operating room (OR). This may involve patient factors, such as upper respiratory infection (URI); surgical factors, such as inadequate hemostasis; and anesthesia factors, such as extubation at an inappropriate depth of anesthesia. For complications to be prevented or treated, it is important to consider all such factors. For the purposes of this chapter, the focus will be on complications that are related primarily to anesthesia or that are influenced by anesthetic technique.

The transition from the OR to the PACU can be a particularly hazardous time. This is, in effect, the time the anesthesiologist is “landing the plane,” to use an aviation analogy. All too frequently, care providers are occupied with numerous tasks that must be carried out, and noise can be very distracting for the anesthesiologist and others caring for the patient. Extubation may have just been performed, anesthetic drugs are still having an effect, and the transport process to the PACU may be less than ideal. In some facilities, there may be a lack of suitable transport stretchers (gurneys), and it may not be easy to administer oxygen or to monitor oxygen saturation (Sp o ₂ ) during the transfer. Some PACUs may be located at a considerable distance from the OR. There will be a transfer of care to another health care provider, usually a PACU nurse, and as with any transfer, this may be a concern if the handover is rushed and important information is missed. In some facilities, the equipment available in the PACU may not be as sophisticated as in the OR. This is especially true in resource-limited settings in many areas of the developing world. Given the importance of this part of the recovery process, it is crucial that the PACU staff have immediate support from other health care providers on the team. A team orientation session reviewing the approach to various complications, before commencing a surgical program, is a very valuable exercise.

Why are post-operative anesthetic complications important? Clearly, any complication after surgery is to be avoided. Morbidity may be apparently minor, such as nausea, but may still be distressing to the patient and family. Events such as emergence delirium (ED) or vomiting may lead to surgical complications, such as bleeding or disruption of skin grafts. Major complications may have very serious consequences. These can include adverse effects on the likely success of surgery, implications for cost of the procedure, negative effects on the caseload that can be undertaken, and harmful consequences for the reputation of visiting or local surgical teams. In the very worst circumstances, long-term disability or even death may occur. This is a devastating result for the patient, family, and community and may put future surgical programs at risk.

This chapter will provide an outline of important post-operative anesthetic complications, describing their causes, prevention, and treatment.

Respiratory Complications

The most common early post-operative complications are respiratory in nature. In children, the most common predisposing condition is URI. Children may have numerous viral URIs every year, and the effects of these may last for weeks. It is sometimes difficult to find a time when a child does not have a URI or is recovering from one. Complications of URIs encountered in the PACU may include laryngospasm, bronchospasm, coughing, breath holding, and hypoxemia. Prevention may require postponement of the case, but of course this may be very disappointing for the family if surgical resources and opportunities for surgery are limited. Inhaled bronchodilators (e.g., salbutamol) have been evaluated as a prophylactic measure in patients with a URI, with some good results. Other factors that may predispose the child to respiratory complications include exposure to cigarette smoke and other air pollutants, as well as any comorbidity such as asthma or former prematurity. Additionally, anesthesia conducted at high altitude results in lower respiratory reserve due to the lower baseline Sp o ₂ .

Treatment of laryngospasm is along the same lines as that described for anesthesia emergencies ( Chapter 1.6 ). In the PACU setting, it is important that the essential equipment and drugs to treat laryngospasm are immediately available, for example, monitoring equipment including pulse oximetry; a breathing circuit capable of positive pressure ventilation with 100% oxygen, even in the absence of electric power supply; and appropriate face masks and oropharyngeal airways, suction, atropine, and succinylcholine. Propofol, if available, is a very useful agent for terminating milder cases of laryngospasm.

Bronchospasm in the PACU is less commonly seen and generally is related to preexisting reactive airway disease, smoking or other air pollutants, recent airway manipulation, URI, blood or secretions in the upper airway, or some combination of these factors. Most cases can be managed by a bronchodilator (e.g., nebulized salbutamol solution [2.5 mg <20 kg; 5 mg >20 kg]), and it is important that the PACU is equipped with appropriate delivery systems. Salbutamol (alternative names: albuterol, Ventolin) may also be given by a dry inhaler.

Children seem particularly prone to breath holding as they emerge from anesthesia. This is often preceded by a cough or coughing spell. A saying in pediatric anesthesia circles is to “beware the child who coughs.” This may progress to the point where the child tenses the chest wall muscles, closes the glottis, and ceases to make effective respirations. The child is often not fully awake at this point. Even if the glottis is still partially open, it may be very difficult to ventilate the child due to the chest wall rigidity. This is a variation of laryngospasm. Unless managed promptly, severe oxygen desaturation may result. Treatment is similar to that for laryngospasm, and frequently a small dose of propofol (1–2 mg/kg) will terminate the event.

Adults who smoke are also prone to coughing spells in the post-operative period. This may be no bad thing, because they will clear tracheobronchial secretions and expand atelectatic areas in the process. Such adults often are best managed in the sitting position. Severe, distressing coughing may be reduced by a small dose of an opioid.

One complication that is rarely seen today is post-operative stridor due to subglottic edema in children. This was more commonly seen when the use of thick-walled red rubber endotracheal tubes was routine. In some centers, red rubber tubes or other tubes of poor design may still be in use, so this complication may be encountered. The evidence suggests that cuffed or uncuffed endotracheal tubes of modern design and appropriate size are unlikely to produce subglottic edema. When it does occur, treatment is with oxygen, IV dexamethasone (0.2–0.6 mg/kg) and, in severe cases, inhalation of 2.5 to 5 mL of nebulized 1 : 1000 L-epinephrine.

Persistent oxygen desaturation may occur in any post-operative patient. Often the cause is multifactorial. Predisposing factors may include any lung pathology, obesity, obstructive sleep apnea syndrome, high altitude, and sedative effects from anesthesia and analgesia. All forms of general anesthesia may produce a fall in lung volumes (e.g., functional residual capacity), which eventually may lead to atelectasis at a micro or macro level. This is not always easy to prevent. Sophisticated ventilators during surgery are not always available in many locations, and even if they are, the benefits of newer modes of intraoperative ventilation are not clear. One of the simplest measures to reduce atelectasis before extubation is to employ some alveolar recruiting maneuvers manually with positive pressure ventilation.

Another important cause of persistent oxygen desaturation is post-obstructive pulmonary edema. Any episode of upper airway obstruction, where there are forceful efforts to breathe against the obstruction, may lead to post-obstructive pulmonary edema. The classic cause for this is laryngospasm. In severe cases, diffuse crackles may be heard in both lung fields, pink frothy fluid may be seen in the airway, and signs of pulmonary edema may be seen if a chest radiograph is available. Typically, the condition responds well to oxygen, diuretics, and time.

Whatever the cause of persistent post-operative desaturation, it must be managed thoughtfully and not only by the use of oxygen. The patient must be examined and a chest radiograph obtained if indicated and available. Any treatable cause for oxygen desaturation (e.g., bronchospasm) should be managed appropriately.