Hypoxemic Episodes of Patients in a Postanesthesia Care Unit: Comparison of Present Results to Bast Studies

Hypoxemic Episodes of Patients in a Postanesthesia Care Unit: Comparison of Present Results to Bast StudiesMany of the factors correlating with hypoxemic episodes in this study’s patient population agree with past findings. This is particularly apparent for patient weight, age, ASA class, duration of the surgical procedures and anesthesia, general rather than regional anesthesia, and volume of intravenous fluids received intraoperatively. However, higher narcotic doses did not result in more frequent or longer desaturations. Smoking history was also not associated with hypoxemia. The positive association between desaturations and peripheral rather than abdominal surgery was surprising. Most of the peripheral procedures were orthopedic, often performed on healthy young patients in ASA class 1. However, many of these procedures were longer in duration than the abdominal surgeries, which included both upper and lower abdominal surgery. Missing from the abdominal surgery group were patients admitted into the intensive care unit from the operating room, such as those having abdominal aortic aneurysm resections. The longer duration of desaturations in female patients may be related to their tendency, although no significant difference was seen, to weigh more. A larger study population may clarify this. There was no trend toward a difference in age.
The 15 percent incidence of desaturations below 92 percent on PAR admission is in keeping with the range previously reported for postoperative transport to PAR. The 25 percent incidence of arterial oxygen desaturations during PAR stay with oxygen administration exceeds the 6 percent documented by Smith et al and the less than 1 percent reported by Hudes et al. There are differences between these studies that help explain this. Smith et al began Sa02 monitoring only 15 to 30 min after RR admission, not immediately. Hudes et al, however, recorded Sa02 immediately on admission, and then again 15 min later. The Sa02 monitoring in those patient groups was intermittent. Bronchoscopy
There are many similarities as well as distinctive differences from the results found in this study and those of Daley et al. Although they recorded data continuously, data collection began 5 min after admission and may have missed initial low saturations, while recording was begun on PAR admission before oxygen supplementation was begun in this study. At least one hypoxemic episode (defined as SaOs ^90 percent for ^30 s) occurred in 41 percent of their patients. However, there were no hypoxemic episodes during oxygen supplementation; all desaturations occurred after oxygen discontinuation. Desaturations in this study were found during oxygen supplementation. Excluding hypoxemia on admission, desaturations occurred relatively late, or 32 ±54 min after admission in the present study, as compared with Daley et al, finding desaturations occurring 82 ± 32 min after admission and 26 ± 18 min after oxygen discontinuation. The duration of desaturations was similar: 5.2 ±2.6 min in this study as compared with 5±5 min. The ASA status and surgical duration were risk factors for postoperative hypoxemic episodes in both populations studied.
Specific patients were excluded from these other studies. For example, Hudes et al excluded patients with a preoperative Pa02 less than 60 mm Hg, previous central nervous system or musculoskeletal disease affecting respirations, and those who demonstrated airway obstruction, coughing, or cardiovascular instability on transport to the RR; Smith et al also required hemodynamic stability and normothermia as well as the attending nurses being satisfied with the condition of the patient. Daley et al excluded several patient groups, including the morbidly obese and those with the sleep apnea syndrome. Many patients at risk for desaturation may have been excluded from both studies. Exclusion of patients from the study group could contribute to the low reported incidences of desaturations.

This entry was posted in Hypoxemic Episodes and tagged abdominal surgery, anesthesia, hypoxemia, oxygen saturation, postoperative hypoxemia.