2.1 AIRWAY OBSTRUCTION

The most common serious respiratory complications after UPPP are airway obstruction and oxygen desaturation. Complete and untreated airway obstruction may lead to respiratory arrest, and reintubation or emergency tracheo-tomy could become necessary and lifesaving.

Although airway obstruction may be considered a common postoperative complication after UPPP, the actual incidence of such an event is quite low. Additionally, there has been a change in the number of serious respiratory complications reported over time, with more recent studies reporting lower rates. For example, in 1989 Esclamado et al.¹⁰conducted a retrospective chart review of 135 patients surgically treated for OSA and found the incidence of respiratory complications to be 10.3%. Half of these complications were airway obstructions that occurred at extubation, and half were due to failed intubation. It is important in a discussion of postoperative management to note that the onset of all respiratory events occurred in the early phase. That is, all respiratory complications occurred during or immediately after intubation. A review in 1994 by Haavisto and Suonpaa¹¹ of 101 patients undergoing UPPP for OSA showed an incidence of airway complications of 11%. Again all cases occurred in the early phase.

In a 1998 review of 109 patients undergoing UPPP for OSA, Terris et al. reported a 5.5% incidence or early respiratory complications.⁶ This rate included one case of airway compromise, and the patient required naloxone, oxygen and suctioning of his airway. This single episode of airway obstruction occurred only 15 minutes after the patient was transferred out of the operating room.

An additional 1998 study by Mickelson and Hakim of 347 patients undergoing UPPP for OSA reported only five patients who had experienced airway-related complications, or 1.4% of all patients.⁵ Three of the five suffered shortness of breath either at extubation or immediately after in the recovery room. Two of the five patients experienced complications in the surgical ward. These included one case of pulmonary edema and one case of shortness of breath of unclear origin. No actual cases of airway obstructions were reported.

Spiegel and Raval reviewed 117 patients in 2005 for complications associated with UPPP.⁸ Ten patients were discharged the same day as the surgery. The remainder of the patients experienced a 4.3% incidence rate of respiratory complications. While most cases were due to oxygen desaturation, two patients developed airway obstruction from presumed laryngospasm at the time of extubation. Both of these patients developed postobstructive pulmonary edema within minutes of the obstruction.

Overall, the rate of airway obstruction appears to be in the range of 1.4–11%. Most importantly, obstruction events appear to occur immediately after surgery in the early phase of recovery, so it is not likely that an extended period of observation would be a useful way to prevent this type of complication.

2.2 OXYGEN DESATURATION

Oxygen desaturation is also often cited as a common complication in OSA patients undergoing UPPP. A value of less than 85–93% is typically considered significant desaturation. In the past, some surgeons have advocated postoperative ICU monitoring for fear of serious desaturation events. However, such monitoring may not be reasonable since most desaturations occur in the early phase of recovery. Additionally, more mild nocturnal desaturations may continue for weeks, since UPPP does not correct OSA immediately.¹²

The fact that most occurrences of desaturations happen relatively early in the recovery process further supports same-day patient discharge for the majority of patients. For example, in a 2006 study by Hathaway and Johnson of 110 patients undergoing UPPP, desaturations in three patients all occurred in the recovery room.⁷ In the review by Spiegel and Raval, three desaturations below 90% were reported.⁸ The first desaturation occurred in the recovery room, the second on the first postoperative night and the third on the first postoperative day. The third patient likely desaturated on the first postoperative day because he was given narcotic patient-controlled analgesia (morphine) for pain, and narcotic analgesia tends to impede respiratory function.

Advocates of extended postoperative stays after UPPP also claim the need for post-surgical oxygen supplementation on the floor as an important argument for hospitalization. However, there is some evidence that there may not be a direct relationship between oxygen supplementation and lower desaturation rates. For example, Riley et al.¹³ found no significant difference in the postoperative low oxyhemoglobin saturation (LSAT) between patients receiving continuous positive airway pressure (CPAP) and the non-CPAP group.

A patient’s preoperative Respiratory Distress Index (RDI) may also be a poor predictor of whether or not they may desaturate, as was the case in the review by Hathaway and Johnson.⁷ While two of the admitted patients had RDIs over 50 (indicating severe OSA) one patient had an RDI of 22 and still desaturated. Desaturations occurred in the recovery room, and all patients were admitted into the hospital, but none required the ICU. The authors concluded that preoperative polysomnography data such as the RDI may not predict which patients will experience desaturation in the early postoperative period.

Overall, research shows that desaturation, particularly nocturnal desaturation, is a very common complication of UPPP surgery for OSA. In fact, it should be considered more of an expectation than a complication. Giving oxygen postoperatively may or may not make a difference, so admitting all UPPP patients in order to give them oxygen would not be reasonable. Also, preoperative sleep indices may not be an accurate indicator for identifying patients who may desaturate, so it would not be practical to hospitalize all patients due to fear of this complication. The most likely scenario is that if a serious desaturation occurs, it would be in the early phase of recovery, at which point the patient should be admitted to the hospital. Otherwise, minor nocturnal desaturations are to be expected since it may take a few weeks to note improvement in a patient’s OSA.