The incidence of postoperative hypoxaemia during transportation to the recovery area
*Anna Dylczyk-Sommer, Wioletta Sawicka, Maria Wujtewicz
Department of Anaesthesiology and Intensive Therapy, Medical University of Gdańsk
Background. Transportation to the recovery room after surgery can be associated with significant hypoxaemia, if a portable oxygen source and a pulse oximeter are not used. We analysed the condition of patients on admission to recovery after being transported from the operating room without additional oxygen and monitoring.
Methods. One hundred and thirty-one ASA II and III patients, aged 58.2±15.96 years, were enrolled to the study. SaO2 readings immediately before transportation, and on arrival in recovery, were compared. Additionally, blood-gas analysis was performed 10 min after admission to the recovery room. The duration times of transport (T1), lack of monitoring (T2) and breathing with room air (T3) were measured.
Results. The mean SaO2 before transportation was 96.9±10.55%, and on arrival in the recovery room was 93.0%±6.35. The mean T values were: T1 – 90.0±94.2 s, T2 – 152.6±86.6 s, and T3 – 122.9±86.8 s. Although the length of transport time was relatively short, mild hypoxaemia was observed in all patients, with the SaO2 returning to normal after 10 min on 40% oxygen. Blood gas analysis revealed mild respiratory acidosis in 73% of cases.
Conclusion. Additional oxygen via face mask and appropriate monitoring should be provided to all patients during transportation from the operating room to the recovery area.
With the advances in surgery and anaesthesiology, the number of surgical procedures, which often require additional preoperative care of patients, is becoming increasingly high. The profile of patients undergoing surgery has been changing, more older patients and those with co-existing diseases are qualified. Therefore, in many surgical specialities, the outcome of treatment depends more often on the preoperative preparation of patients and suitable postoperative care than the procedure itself [1, 2]. Numerous studies were devoted to appropriate preoperative preparation of patients for anaesthesia and surgery, yet only a few to suitable postoperative care .
Recently, the safety of surgical procedures, thus the safety of patients undergoing these procedures has become essential, which is reflected in the Declaration of Helsinki accepted during the Congress of the European Society of Anaesthesiology of 2010 [3, 4, 5].
After surgery, the majority of patients are sent to recovery units or rooms where their basic vital functions are monitored, which markedly increases their safety and comfort of work of anaesthesiologists. However, the period of transportation from the operating to the recovery room remains an extremely dangerous and often underestimated. In many cases, patients are transported without any monitoring or oxygen therapy [6, 7, 8, 9]. The risk of apnoea and other ventilation disorders amongst patients transported to operating rooms after premedication has been emphasized for years; yet only a few studies focused on the safety of patients immediately after recovery from anaesthesia and during transport to the sending wards or recovery rooms  and this period may lead to unanticipated adverse effects, particularly of the respiratory and cardiovascular system [7, 8, 10, 11].
The objective of the study was to evaluate the gas exchange disturbances in the lungs occurring during transport of a patient from the operating room to the recovery area and to optimize the management strategies in this period.
The prospective study was carried out with the approval of the Bioethics Committee attached to the Medical University of Gdańsk. The study included ASA II and III patients of both genders operated on under general anaesthesia who recovered from anaesthesia in the operating room. The anaesthetic procedures were performed within the operating suite with the recovery room included. Patients were transported to this room after surgery without oxygen therapy and monitoring of vital functions. The timing of leaving the operating room was decided by the attending anaesthesiologist.
We compared blood haemoglobin saturation measured percutaneously on leaving the operating room and admission to the recovery room. In the recovery room passive oxygen therapy was routinely used; to evaluate the gas exchange objectively, the parameters of acid-base balance of arterial blood were assessed after 10 min of oxygen therapy applied.
Moreover, the duration time of transport– T1, lack of monitoring – T2 and lack of oxygen therapy – T3 were assessed.
The study encompassed 131 patients aged 58.2±16 years. The mean value of saturation on leaving the operating rooms was 96.9±10.5% whereas on admission to the recovery room 93±6.35%. Decreased SpO2 was observed in all patients.
After 10 min of oxygen therapy, the values of acid-base balance parameters were: pH 7.31±0.05, PaCO2 48±6.4 mm Hg, (6.4±0.8 kPa) PaO2 126±86.8 mm Hg (16.8±11.6 kPa). In total, hypercapnia was observed in 73% of patients. Although the mean PaO2 measured after 10 min of oxygen therapy was normal, hypoxaemia was still found in some patients (range PaO2 55-258 mm Hg/7.3-34.4 kPa).
The mean time of transport from the operating to the recovery room (T1) was 90±10.55 s, the mean time lacking monitoring (T2) – 152.63±86.63 s whereas that without oxygen therapy (T3) – 122.9±86.8 s.
Although the mean time of transport from the operating room to the recovery unit was relatively short, i.e. 1.5 min, the time without monitoring of basic vital functions was longer – 2.5 min, on average. It is noteworthy that the time without monitoring markedly varied (from 6 s to 10 min ) and mainly resulted from organization-related and communication problems between the operating room and recovery unit staff. Moreover, the time without oxygen therapy was slightly longer than the transport time – over 2 min. During this period, decreased SpO2 was observed in all patients compared to its value on leaving the operating room.
During the study period, favourable changes in the work-related patterns of the recovery unit personnel were observed. The time of transport was becoming increasingly short, which resulted from the preparation of the recovery unit team for admission of patients from the operating room. Furthermore, the management strategy in the unit changed: first, the facial mask was placed and oxygen therapy initiated, then the pulse oximeter sensor was connected, which contributed to shortening of T2 and T3 compared to initial values [12, 13, 14, 15]. Thus, the study exerted significant educational effects, making the staff realize that even slight organization-related changes may contribute to marked improvement of patients’ safety.
The study was conducted within the operating suite in which the distance between individual operating rooms and the recovery unit was only 20-50 m. In many hospitals, however, some surgical patients are not transported to the recovery unit but to sending wards. If passive oxygen therapy is not provided and vital functions are not monitored during transport, the risk of complications is likely to be higher [3, 7, 10, 12, 14]. Moreover, it was demonstrated that the number of interventions during the postoperative period among ASA I patients hospitalized in the recovery unit was quite high and concerned 40% of all patients undergoing minor surgical procedures. This indicates that young patients without concomitant diseases should be postoperatively monitored, irrespective of the procedure type [4, 12, 13].
According to the Declaration of Helsinki, each year about 230 million patients worldwide undergo anaesthesia for major surgery. Severe surgery-related complications develop in 7 million of them, with one million resultant deaths. Therefore, everybody should strive for reduction of this index  .
One of the relevant elements affecting the safety of patients is a „human factor” and educational activities. The changes in work-related patterns of the recovery unit personnel resulting from such activities are considered by us the greatest benefit of the present study.
1. To provide the patients undergoing surgery under general anaesthesia with safety, they should be transported immediately after surgery with oxygen therapy administered due to the risk of hypoxia.
2. Patients after general anaesthesia should be observed in the recovery room due to the risk of hypoventilation.
3. In each patient transported from the operating room, basic vital functions should be monitored.
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Klinika Anestezjologii i Intensywnej Terapii
Gdański Uniwersytet Medyczny
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