M. Harmer

The effect of education, assessment and a standardised prescription on postoperative pain management: The value of clinical audit in the establishment of acute pain services

A study involving 2738 patients in 15 hospitals in the United Kingdom was undertaken to evaluate the effect of simple methods of pain assessment and management on postoperative pain. The study consisted of four parts: a survey of current practice in each hospital; a programme of education for staff and patients regarding pain and its management; the introduction of formal assessment and recording of pain and the use of a simple algorithm to allow more flexible, yet safe, provision of intermittent intramuscular opioid analgesia; and a repeat survey of practice. One hospital from each of the former health regions of England and Wales was selected for inclusion in the project. Hospitals included representatives of different size units (university, large and small district general hospitals). As a result of the study, there was an overall reduction in the percentage of patients who experienced moderate to severe pain at rest from 32% to 12%. The incidence of severe pain on movement decreased from 37% to 13% and moderate to severe pain on deep inspiration from 41% to 22%. Similar decreases were seen in the incidence of nausea and vomiting. There was also a slight reduction in the incidence of postoperative complications. This study shows that simple techniques for the management of postoperative pain are effective in reducing the incidence of pain both at rest and during movement and should form part of any acute pain management strategy.

Single-breath inhalation induction of sevoflurane anaesthesia with and without nitrous oxide: a feasibility study in adults and comparison with an intravenous bolus of propofol.

The induction characteristics of sevoflurane in nitrous oxide and oxygen were compared with sevoflurane in oxygen alone and a propofol infusion. A vital capacity technique was used for the gaseous induction groups using a Mapleson A system and a 4‐litre reservoir bag. Four end‐points of anaesthesia were recorded: time to cessation of finger tapping, time to loss of eyelash reflex, time to jaw relaxation and time to regular settled breathing after laryngeal mask airway insertion. We also recorded sequential blood pressure and pulse rate, the incidence of adverse airway events and the acceptability of the induction technique. Propofol had a faster time to cessation of finger tapping (p <0.05) and jaw relaxation (p <0.01). These differences disappeared with the final induction stage and sevoflurane in nitrous oxide and oxygen had the faster time to regular settled breathing, though this did not reach statistical significance. Cardiovascular stability was good and comparable in all groups. There were few adverse airway events in any group and none caused oxygen saturation to fall below 96%. There was more excitation in the gaseous induction groups, though this did not interfere with induction. Patient satisfaction with induction was high.

Spatially resolved spectroscopy (NIRO-300) does not agree with jugular bulb oxygen saturation in patients undergoing warm bypass surgery

PurposeNear infrared spectroscopy (NIRS) is a promising noninvasive method for continuous monitoring of cerebral oxygenation during cardiac surgery with cardiopulmonary bypass (CPB). This study was designed to study the agreement between tissue oxygen index (TOI) measured by spatially resolved spectroscopy (NIRO- 300) and jugular bulb oxygen saturation (SjO2) in patients undergoing warm coronary bypass surgery.MethodsSeventeen patients undergoing warm coronary artery bypass surgery were studied. NIRS was continuously monitored and was averaged before CPB, five, 20, 40, 60 min on CPB, five minutes before end of CPB and ten minutes after CPB to coincide with SjO2 measurements. Bypass temperature was maintained at 34–37°C.ResultsBland and Altman analysis showed a bias (TOI-SjO2) of- 6.7%, and wide limits of agreement (from 16% to –28%) between the two methods. In addition, mean TOI was lower than mean SjO2 during and after CPB. We observed a statistically significant correlation between arterial carbon dioxide and SjO2 measurements (r2=0.33;P=0.0003), but the former did not correlate with TOI values (r2=0.001;P=0.7).ConclusionOur results demonstrate a lack of agreement between SjO2 and TOI for monitoring cerebral oxygenation during cardiac surgery. We conclude that the two methods are not interchangeable.RésuméObjectifLa spectroscope proche infrarouge (SPIR) est une méthode non effractive et prometteuse de monitorage continu de l’oxygénation cérébraie utilisée en chirurgie cardiaque sous circulation extracorporelle (CEC). L’étude actuelle voulait tester la concordance entre l’index d’oxygène tissuiaire (I0T) mesuré par spectroscope à résoiution spatiaie (NIRO- 300) et la saturation en oxygène du golfe de la jugulaire (SjO2) pendant une cardioplégie chaude.MéthodeDix sept patients subissant un pontage coronarien sous cardiopiégie chaude ont été étudiés. La SPIR a été surveillée continûment et ajustée avant la CEC, à cinq, 20, 40, 60 min pendant la CEC, cinq minutes avant la fin de la CEC et dix minutes après pour coïncider avec les mesures moyennes de SjO2. La température a été maintenue à 34– 37°C pendant la CEC.RésultatsL’analyse de Bland et Altman a montré un biais (IOT- SjO2) de − 6,7 % et de larges limites de concordance (de 16% à − 28 %) entre les deux méthodes. De plus, l’IOT moyen était plus bas que la SjO2 moyenne pendant et après la CEC. Il existait une corrélation statistiquement significative entre le gaz carbonique artériel et les mesures de SjO2(r2 = 0,33; P = 0,0003), mais non entre le CO2 et les valeurs de l’IOT (r2 = 0,001; P = 0,7).ConclusionNos résultats démontrent un manque de concordance entre la SjO2 et l’IOT lors du monitorage de l’oxygénation cérébrale pendant une intervention cardiaque. Les deux méthodes ne sont donc pas interchangeables.

Evaluation of personal, environmental and biological exposure of paediatric anaesthetists to nitrous oxide and sevoflurane

Summary Paediatric anaesthetists are at higher risk of exposure to waste anaesthetic gases, which often exceed set safety limits. Recommended personal diffusive sampling techniques for monitoring exposure to waste anaesthetic gases may not give a true profile of exposure and hence biological sampling may also be necessary. We evaluated the exposure of paediatric anaesthetists to nitrous oxide and sevoflurane as assessed by personal environmental and biological samples. The influence of venue and technique, and the strength of the relationship among the various sampling techniques were analysed. The study found that exposure to nitrous oxide during paediatric anaesthetic inductions is still a major problem, although exposure to sevoflurane was usually within the accepted limits. The type of breathing system used and the presence of scavenging seem to influence this exposure, though surprisingly, the induction technique or the methods of airway control do not. No significant relationship was found between the various biological indicators measured.

Jugular bulb oximetry during cardiac surgery

Imbalance between cerebral oxygen supply and demand is thought to play an important role in the development of cerebral injury during cardiac surgery. This article presents an overview of cerebral oxygenation monitored by jugular bulb oximetry during cardiac surgery with cardiopulmonary bypass. The general principles of jugular bulb oximetry including physiology, intermittent and continuous monitoring, technical considerations, limitations and potential complications are discussed. Different applications of jugular bulb oximetry during bypass surgery and the possible therapeutic approaches to impaired cerebral oxygenation are described.

A change in resistance? A survey of epidural practice amongst obstetric anaesthetists

Five hundred members of the Obstetric Anaesthetists Association were surveyed regarding their technique for identification of the epidural space. Eighty‐one per cent of the questionnaires were returned completed. Fifty‐nine per cent of respondents first learned a loss of resistance to air technique, 33.4% to saline and 7.4% another technique. Presently, 37.1% and 52.7% use only a loss of resistance to air or saline, respectively. Six per cent use both techniques and 3.2% use other techniques. Twenty‐eight per cent taught a loss of resistance to air, 57.2% taught a loss of resistance to saline and 12.9% taught both techniques. Twenty‐three per cent changed from a loss of resistance to air, to a saline technique, and 4.2% vice versa. Forty‐seven per cent of those using air felt that loss of resistance to air was not associated with a clinically significant difference in the incidence of accidental dural puncture compared with saline.

The bacterial and viral filtration performance of breathing system filters.

The bacterial and viral filtration performance of 12 breathing system filters was determined using test methods specified in the draft European standard for breathing system filters, BS EN 13328‐1. All the filters were of two types, either pleated hydrophobic or electrostatic, and these two types differed in their filtration performance. The filtration performance is expressed in terms of the microbial penetration value, defined as the number of microbes passing through the filter per 10 million microbes in the challenge. The geometric mean (95% confidence limits) microbial penetration value was 1.0 (0.5, 3.5) and 2390 (617, 10 000) for the pleated hydrophobic and electrostatic filters, respectively, for the bacterial challenge, and 87 (48, 212) and 32 600 (10 900, 84 900), respectively, for the viral challenge. In general, there was little change in the microbial penetration values following 24 h simulated use. It is concluded that results from the tests specified in the draft standard will allow comparisons to be made between different manufacturers’ products enabling an informed choice to be made.

Cardiopulmonary bypass temperature and brain function

A debate has emerged in recently published studies about the optimum cardiopulmonary bypass temperature for good neurological outcome – warm vs. cold, i.e. normothermic vs. hypothermic. Although many comparative studies have been performed, the results of these studies are inconclusive and are difficult to interpret. Brain function has been studied in terms of neurological and neuropsychological outcome, protein S100β levels as a marker of brain damage, and cerebral oxygenation using jugular bulb oximetry and near‐infrared spectroscopy. The studies produce no conclusive proof of the superiority of warm or cold cardiopulmonary bypass. However, it appears that any degree of bypass hypothermia (< 35 °C) may protect the brain. On the other hand, even a slight increase in bypass temperature to > 37 °C may cause marked brain injury.

Induction characteristics with 3% and 8% sevoflurane in adults: an evaluation of the second stage of anaesthesia and its haemodynamic consequences

The second stage of anaesthesia was examined during 3 and 8% sevoflurane induction to see if any shortening of its duration was at the expense of cardiovascular stability. Fourteen volunteers underwent consecutive, randomly ordered inductions. Pupil size, skin sympathetic activity, plasma catecholamines, blood pressure and heart rate were measured. Eight per cent sevoflurane produced significantly shorter times to loss of consciousness (mean 68 s (SD 18) vs. mean 150 s (SD38)) and durations of second stage (mean 58 s (SD 38) vs. mean 91 s (SD 46)). Blood pressure, heart rate and sympathetic nerve responses were the same in both groups. Compared with baseline, skin sympathetic activity was greatest during pre‐oxygenation (not significant) and unaltered during second stage. Both groups showed significantly increased plasma norepinephrine and heart rate and decreased blood pressure from baseline. Eight per cent sevoflurane induction produced a shorter second stage than 3% with equal cardiovascular stability and the same sympathetic response.

Editorial Maternal mortality — is it still relevant?

Since the introduction of the Confidential Enquiries into Maternal Deaths (CEMD) in 1952 there has been a steady decrease in the overall incidence of maternal deaths. More particularly, with successive reports, there has been a regular reduction in the number of deaths due to anaesthesia. It might therefore cause some concern to find that the latest CEMD shows an increase in the number of deaths attributed to anaesthesia [1]. However, before accepting this de facto, it might be prudent to question the reason for this increase? Has there really been an increase (and hence an implied deterioration in standard of practice) or is this the result of a change in emphasis by those assessing the deaths. Might it also just reflect the ever increasing expectations of both patient and clinician and thus changes in what is considered acceptable practice. A maternal death in the postoperative period, which in the past might have been considered as multifactorial in causation and possibly unavoidable, may today be considered distinctly avoidable with proper intensive therapy. But this must then beg the question as to whose responsibility is it to ensure such therapy is provided. The latest CEMD includes a number of deaths directly attributed to anaesthesia that occurred as a consequence of the anaesthetist, amongst others, failing to appreciate the need for urgent ITU admission. Of course, such admission is no guarantee that death would not still have occurred, but would be considered as acceptable practice. Thus, one important feature of this latest report is that the responsibility for ensuring adequate care in such cases seems to have been placed directly at the door of the anaesthetist. A postoperative death which in the previous reports might have been considered as indirectly associated with anaesthesia has in this report appeared as a direct anaesthetic death. Is this seeming shift of responsibility unreasonable or have our skills and available facilities become such that we should accept that the expected standard of care should also have changed? If the deaths detailed in this latest report are compared with those in the previous report [2], there is actually very little difference in the overall number associated either directly or indirectly with anaesthesia, the increase in direct deaths being largely attributable to the change in emphasis (or expectation) within this report, a fact reinforced by the appearance for the first time of a chapter on intensive therapy. This slight change in emphasis is likely to occur with each successive report with the ‘goalposts’ being shifted to reflect the current expectations. But even the expectations implicit in a report may not reflect current practice as each report appears some 3 or more years after the period of data collection and some 6 years after some deaths. In a world of rapidly changing expectations, there is always the danger of judging actions by today’s standards rather than those contemporary to the events surrounding the reported death. It could be argued that for a death occurring in 1991 and detailed in the latest report, the recommendations in practice at the time were those contained in the 1985–87 report [3]. Clearly, obstetric anaesthetic practice has changed dramatically in the last decade. If we can account for the apparent increase in the number of deaths attributed to anaesthesia, should we now look seriously at the size of the problem. The actual numbers involved are very small (representing a risk of 3.5 deaths per million pregnancies), such that we may have reached the limit of using studies of mortality to improve practice. Of equal concern with such small numbers is the risk of misinterpretation. For example, if in a report there is one death associated with epidural analgesia and in the next report there are two such deaths, although anyone with any scientific background will appreciate that this does not represent a real change, the media are likely to report: ‘100% increase in deaths due to epidurals’. The impact on the public would be entirely predictable. It would be very tempting to suggest with such a small number of deaths that we should no longer concern ourselves with them and just accept that we have arrived at a level consistent with unavoidable human error (or bad luck!). However, we should be careful before we abandon the CEMD as it still remains the envy of many other countries who have no such system available. If maternal deaths are, thankfully, too infrequent to be a reliable assessment of clinical standards, what can be done to get a better picture of current practice. It has always been accepted that death represents the tip of a morbidity iceberg, the size of which is unknown. As the captain of the Titanic might attest, it can be dangerous to extrapolate the visible information into possible underlying problems. One way in which we might obtain a more accurate assessment of obstetric anaesthetic practice would be to measure morbidity. But that raises the question of how can it be done? Death is a clear end point that is universally understood and is generally well reported because it is a legal requirement. Morbidity, on the other hand, is extremely difficult both to qualify and to quantify. If morbidity was considered as anything other than a perfect result, we would have to include such complaints as sore throat, backache and short-term neurological deficits in a study of morbidity. Whilst one should not belittle such complications, what we are really concerned about is the more severe morbidity that might leave the patient with permanent damage. It is likely that the majority of such patients would have, at some stage, spent time on an intensive care unit. Therefore, one Anaesthesia, 1997, 52, pages 99–100 ................................................................................................................................................................................................................................................