Oxyhaemoglobin saturation following elective abdominal surgery in patients receiving continuous intravenous infusion or intramuscular morphine analgesia

Abstract

SummaryOxygen saturation was continuously measured using computerised pulse oximetry for 8 h overnight pre-operatively and for the ,first 24 h postoperatively in 40 patients receiving intermittent intramuscular morphine or continuous infusion of morphine following elective upper abdominal surgery. The proportion of time with an oxygen saturation less than 94% was used as an index of desaturation. Patients receiving continuous infusion analgesia received a larger morphine dose and achieved better analgesia than the intramuscular group. Postoperatively, the duration of desaturation increased I0,fold over pre-operative values, 'intramuscular' patients spending 39.0% ( S D , 37.0%) and 'continuous infusion' patients 40.0% (SO, 37.5%) of the time below 94% saturation. Although newer therapies (e.g. epidural analgesia and patient-controlled analgesia) are currently receiving greater attention. the seyuelae of these more traditional analgesic techniques warrant further study. Key wordsMonitoring; oximetry. Complications; hypoxia. Analgesics; morphine. Pain; postoperative.During the past 30 years the occurrence of intermittent and sustained postoperative hypoxia has been reported [ 1-31. The introduction of newer methods of opioid delivery e.g. patient-controlled analgesia (PCA) [4] and spinal opioids [5] has promoted considerable research into adverse effects of these techniques, particularly respiratory depression. In contrast, there has been little work looking at what actually happens following traditional methods of opioid delivery such as intramuscular injection (IM) and continuous intravenous infusion (CI). Catling et al., using the indices of respiratory rate, tidal volume, number of apnoeic episodes and partial pressure of carbon dioxide showed there were differences between IM and CI analgesia following cholecystectomy [2]. However, these measurements were intermittent, and pulse oximetry was not used. Continuous pulse oximetry, which has allowed accurate monitoring of pre-operative hypoxaemia, combined with computerised data collection, has enabled comprehensive analysis of patients' peri-operative oxygen saturation (Spo,). Brose et al. [6] comparing IM pethidine, PCA pethidine and extradural morphine for post-Caesarean section analgesia, reported that patients receiving PCA had long periods of mild desaturation (90-95%); in contrast, more severe desaturation (mean values 83%) occurred for shorter periods of time with extradural morphine and intramuscular pethidine. Continuous pulse oximetry was used by Wheatley et al. who studied patients undergoing lower abdominal procedures in order to assess the respiratory effects of extradural, PCA and IM analgesia [7]. These workers defined the pattern of Spo, readings as stable or unstable depending on the hourly variability of oxyhaemoglobin saturations, and hypoxaemia as a n Spo, < 94% for more than 10% of the time. Patients receiving IM and PCA had unstable patterns of Spo, values with no hypoxaemia, while 50% of patients receiving extradural morphine had unstab...

Development of a monitoring protocol for safe use of opioids in children

“…Disturbance of sleep patterns, especially early postoperative elimination of rapid eye movement (REM) sleep and subsequent increase in REM sleep significantly affect Spoz values (Knil€ et al 1990). Kluger et al (1992) summarized their saturation data using a graph of the cumulative percentage of time spent at different saturation values and we have found this most useful in confirming the pattern of hourly Spop recordings made by the ward nurse ( Figure 2). It was noteworthy that the vast majority of hourly Sp02 recordings were in the range of 95-loo%, while the rest were nearly all in the range 90-94%.…”

“…In particular, assessment of respiratory depression using respiratory rate was recommended by these authors. This has been convincingly shown to be of little value (Kory 1957;Catley et al 1985;Wheatley et al 1990;Kluger et al 1992). Respiratory rate does not correlate with oxyhaemoglobin desaturation.…”

“…values may be seen (Catley et al 1985;Wheatley et al 1990Wheatley et al , 1992Kluger et al 1992;Jones, Rae & Sapsford 1992). Disturbance of sleep patterns, especially early postoperative elimination of rapid eye movement (REM) sleep and subsequent increase in REM sleep significantly affect Spoz values (Knil€ et al 1990).…”

Epidural and subarachnoid blockade in children

“…This problem is best detected using continuous pulse oximetry while the patient is breathing air. The intermittent recording of respiratory rate has been shown to be a late and insensitive monitor of hypoventilation [131][132][133] and this cannot be relied upon to give an early warning of this problem. The use of pulse oximetry while breathing air is a more sensitive monitor of hypoventilation [134] and in the absence of other causes of hypoxia such as impaired gas exchange, mild hypoxia (arterial oxygen saturatioǹ 94%) indicates mild hypoventilation.…”

Postoperative pain control in children.

“…For example, it is our experience that the small non-muscle splitting approach used for nephrectomy in infants is considerably less painful than the incision in adults. A fifth of infant nephrectomies managed by the acute pain service in this hospital require no analgesia other than intraoperative narcotic and infiltration of the wound with local anaesthetic, and the others are well managed by intravenous morphine infusions (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) [Lg/kg/h) for the first 24 hours after operation.…”