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Introduction: Hypoxemia is one of the most frequently observed complications after anesthesia. Therefore it is important to detect hypoxemia reliably to prevent serious damage to the patients’ health. Pulse oximetry provides an established method for detecting hypoxemia with a high sensitivity. Recently, fast-track anesthesia has become more and more popular in anesthesia. Fast-track means that the patients are transported directly from the operating room to the ward, without any monitoring. In view of the fact that hypoxemia after anesthesia is common, it is important to examine how reliable the clinical detection of hypoxemia is and if the professional experience of the medical staff affects the quality of the detection.
Material and methods: In our study we examined 1145 patients who underwent an operation at the university hospital of Marburg between May 2009 and January 2010. Inclusion criteria were general anesthesia with intubation tube or laryngeal mask airway and the postoperative stay in the PACU (post-anesthesia care unit). Patients who were given oxygen during transport from the operating room to the PACU, patients who were transferred directly to the intensive care unit and those who were just given a regional anesthesia were excluded from the study. The patients’ oxygen saturation was judged at the entrance to the PACU by the attending anesthetist, one person of the nursing staff and one of the doctoral students based on the clinical signs cyanosis and tachypnoea. Simultaneously, the oxygen saturation was measured by pulse oximeter. The measured data of the pulse oximetry and the staffs’ estimated data based solely on clinical signs were compared in Bland-Altman-Plots. The anesthetists were classified into three groups (resident, fellow, attending) for comparing the quality of their estimated data with their professional experience.
Furthermore, we analysed the quality of the doctoral students’ estimated data during the period of the study. We defined hypoxemia as follows: <90% mild hypoxemia, <85% severe hypoxemia.
Results: The incidence of hypoxemia in our study was 13,8%. The anesthetists detected hypoxemia based on clinical signs with a sensitivity of 8,1%, the nursing staff and the doctoral students with a sensitivity of 2,7%. Our study shows that there is no correlation between the quality of data and the professional experience of the anesthetists (p=0,9892). Additionally, there is no statistically relevant learning curve for the performance of the doctoral students during the period of investigation.
Discussion: Cyanosis and tachypnoea are unreliable clinical signs for detecting hypoxemia. The sensitivity of this method for detecting hypoxemia is very low, even if the staff is experienced (8,1% and 2,7% respectively). For that reason, patients should be monitored by pulse oximetry, if fast-track anesthesia is applied.