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Original Article

Acid aspiration prophylaxis in obstetrics in France: a comparative survey of 1998 vs. 1988 French practice

Tourtier, J.-P.; Compain, M.; Petitjeans, F.; Villevieille, T.; Chevalier, J.-F.; Mercier, F. J.; Benhamou, D.

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European Journal of Anaesthesiology: February 2004 - Volume 21 - Issue 2 - p 89-94

Abstract

Acid aspiration is a major complication of anaesthesia and pregnant women are frequently regarded as being particularly vulnerable. Prevention is thus essential in obstetrics and relies on the combination of several techniques: fasting, pharmacological prophylaxis, preferential use of regional anaesthesia and rapid sequence induction if general anaesthesia is chosen [1]. However, daily practice may differ from recommendations. Thus, in a study conducted in 1988, it was shown that if French anaesthetists were aware of the risk of aspiration in pregnant women and had largely introduced regional anaesthesia in their daily practice, they used cricoid pressure and succinylcholine to an insufficient extent [2]. Anaesthetic practices have since changed and a French national investigation in 1996 showed a continuous increase in the use of regional anaesthesia in obstetrics [3]. However, practices regarding other components of the regimen for preventing the acid aspiration syndrome were not recorded. The aim of this study was to assess the practice of French anaesthetists with regard to the prevention of aspiration in 1998 and to compare it with that described in 1988.

Methods

In August 1998, a questionnaire (see Appendix) was mailed to all maternity hospitals in France (n = 800) using the mailing list of the French Club of Obstetric Anaesthetists (Club des Anesthésistes-Réanimateurs en Obstétrique (CARO)). An accompanying letter explaining the aim of this investigation specified that the questionnaire was confidential and that answers were expected to reflect the general practice of the anaesthetic team and not that of an individual. After 4 months, a reminder letter and a second copy of the questionnaire were sent to those units that had not responded. The type of hospital (university teaching hospital, community hospital, private structure or other) and the number of childbirths per year were recorded. The questionnaire, with a structure slightly modified from the one used in 1988 [2], dealt with six topics:

• general questions regarding the risk of aspiration in obstetrics;

• fasting during labour;

• use of pharmacological prophylaxis and drug(s) used;

• method(s) of analgesia during labour;

• techniques used for routine general anaesthesia (including use of tracheal intubation, nasogastric tube, cricoid pressure and succinylcholine);

• management of difficult intubation.

Results are presented in percentages and compared with those obtained in 1988 by χ2-analysis.

Results

Two-hundred-and-two of the 800 questionnaires that had been sent (corresponding to the number of French maternity hospitals registered in 1998) were returned. Two of these had to be excluded, as they were incomplete. In 1988, 297 units had responded, of which nine had had to be rejected [2]. Thirteen percent of the responding units were part of a university teaching hospital, 59% were in a community hospital and in a private structure in 37%. In 23% of the maternity units that responded, the number of annual childbirths was less than 500, whereas in 36% it was between 500 and 1000, in 25% between 1000 and 2000, in 13% between 2000 and 3000, and in 3% it was more than 3000. No significant differences in practice were found when comparing maternity departments according to the number of annual deliveries. However, university teaching hospitals had a significantly better implementation of aspiration prophylaxis techniques than community hospitals or private structures.

In 1998, 87% of the responding anaesthetists thought that obstetrics had a particularly high risk of aspiration (91% in 1988, not significant), and 97% believed that preventive measures were useful (80% in 1988, P < 0.05). Epidural administration of sufentanil or fentanyl with the local anaesthetic during labour was thought to have no effect on gastric emptying by 29% of responding units, 20% thought that it slowed it down and 51% did not know. During labour, strict 'nil by mouth' guidelines were observed in 80% of the responding maternity hospitals; fluids only were allowed by 19%, whereas a light meal was allowed by 1% of them. Pharmacological prophylaxis was administered to every woman in labour in 78% of the maternity hospitals (vs. 62% in 1988, P < 0.05) and before Caesarean section by 97% of responders (vs. 75% in 1988, P < 0.05). Effervescent cimetidine (cimetidine 200 mg combined with a dose of citrate equivalent to 30 mL of 0.3 M solution) was the most widely used preparation (62%) whereas effervescent ranitidine and intravenous (i.v.) cimetidine were used in 19% and 4%, respectively. In the 1998 survey, epidural and/or spinal anaesthesia was the technique of choice for analgesia during labour in 93% of the responding units. Anaesthetic techniques used for scheduled Caesarean section and the use of endotracheal intubation in typical obstetric situations are presented in Figure 1. Epidural anaesthesia was described as the technique of choice by 99% of the responders for emergency Caesarean delivery if an epidural catheter had been previously inserted. In the absence of a functioning epidural catheter, spinal anaesthesia was preferred by 86% of the responding units. Cricoid pressure was used in 88% of the units (vs. 50% in 1988, P < 0.05). Eighty percent of the responding teams stated that they initiated it during induction; the pressure was released after cuff inflation by 90%. Correct and complete description was obtained in 80% of the answers (vs. 52% in 1988, P < 0.05). A nasogastric tube was always inserted by 5% of the responders, sometimes by 26%, and never by 69%. Succinylcholine was administered regularly by 47% of the responders, sometimes by 33%, and 20% never used it, whereas in 1988, 25% of the specialists routinely used succinylcholine. The use of a priming dose of a non-depolarizing neuromuscular blocking agent was not reported by any team in 1998 (vs. 14% in 1988).

Figure 1
Figure 1:
Anaesthetic techniques used in obstetrics in the 1988 and 1998 surveys. GA: general anaesthesia. □: 1988; ▪: 1998.

A protocol describing the strategy for difficult intubation was available in the obstetric suite in 40% of maternity hospitals and special equipment was provided in 90% of them.

Discussion

The main results of this study are that the practices used to prevent aspiration of gastric contents in obstetrics in France improved between 1988 and 1998. The use of regional anaesthesia has continued to increase, pharmacological prophylaxis is prescribed more often, and succinylcholine and cricoid pressure are more widely used. However, the practice of a significant proportion of anaesthetists still differs from accepted guidelines [1].

There are several potential limitations to the interpretation of our results. The response rate was only 25%, which may seem low when compared with other studies [4,5]. There are, however, indirect arguments that support the validity of our results. First of all, the distribution according to type of practice (academic vs. non-academic vs. private centres) and to number of annual deliveries is in agreement with other data from France [6]. Second, the distribution of anaesthetic techniques used for Caesarean section is in close agreement with that found by Clergue and colleagues in a national survey performed in 1996 [3]. Moreover, it represents the opinion of 200 anaesthetists involved in obstetrics, and this is of value in itself. Finally, responders from CARO probably represent a self-selected group of anaesthetists who are particularly interested in obstetrics and whose practices may be different from (and presumably better than) those of anaesthetists not specialized in obstetric anaesthesia.

Anaesthetists were aware that obstetrics carries an increased risk of aspiration. But although the benefit of preventive measures was accepted unanimously when discussed in principle, the practical application varied widely suggesting that the level of risk in the real world is perceived to be much lower. Largescale studies have indeed highlighted the fact that aspiration occurs much more often in emergency abdominal surgery [7]. A recent series in which general anaesthesia was carried out in 1870 peripartum patients (1836 after delivery) without endotracheal intubation, revealed only one case of aspiration [8].

The respondents were often unaware of the effects of epidurally administered opioid analgesics on gastric emptying. We believe this to be of paramount importance as most units now use a local anaesthetic combined with a lipophilic opioid. The opioid dose also seems to play a role. Studies have shown that epidural fentanyl 100 μg [9] - but not 50 μg [10] - impairs gastric emptying and this should be taken into account when general anaesthesia has to be induced in a parturient who has been receiving epidural analgesia for several hours.

Strict fasting was still the rule in 1998 in France as it was in 1988. By contrast, Michael and colleagues reported that in England fasting for solids was usually enforced, but that a strict 'nil by mouth' policy was rarely employed [11]. This policy is found also in Canada [12], in Norway [4] and in the US [13]. Since these studies suggest that this regimen does not increase risk, increased patient comfort and prevention of ketosis would be additional advantages [14]. The 'controlled' liberalization of fasting practices during labour and use of high-calorie-low-fat intake [15] is therefore worth discussing by professionals in France.

In 1998, one French team out of five never prescribed pharmacological prophylaxis for women in labour. Between 1988 and 1998, the use of oral prophylaxis for Caesarean patients increased in France and became similar to the rate found in Germany [5,16], New Zealand [17] and Great Britain [18]. Effervescent cimetidine - a combination of cimetidine and sodium citrate - prevailed, followed by effervescent ranitidine. The latter has a longer duration of action (≥8 h) but its citrate content is too low. An i.v. administration has become rare (as it does not shorten onset of action), suggesting that medical education has been effective [1].

Epidural analgesia was widely used during labour in 1988, but its use has increased further. Our data are in agreement with other surveys. A national survey performed in 1991 described a 33% rate of epidural analgesia during labour [19] that increased to 58% in 1996 [3]. In Caesarean section patients, general anaesthesia was used by 21% of anaesthetists in our 1988 survey. In 1998, general anaesthesia became very rare for a scheduled Caesarean section, again in close agreement with national surveys [3]. The almost universal use of the existing epidural catheter to convert from labour analgesia to Caesarean section anaesthesia is supported by recent studies showing that the rate of failure of extension is very low [20] and probably also explains why the use of epidural analgesia has increased so much.

In the present survey, as in 1988, endotracheal intubation was used in every patient for Caesarean section performed under general anaesthesia. Very different results are found for instrumental delivery and uterine revision under general anaesthesia for which only half of the teams used tracheal intubation. This controversial practice is also found in Canada [12] but as mentioned earlier, a recent study involving a large number of parturients has found this attitude to be acceptable [8].

A nasogastric tube is seldom used during general anaesthesia for Caesarean section in France, Germany [5] and New Zealand [17]. In Norway, on the contrary, a nasogastric tube is inserted in 50% of patients in emergency situations [4]. Insertion of a nasogastric tube before the end of the operation has long been recommended in the UK [21].

The use of cricoid pressure has increased in France since 1988. Obstetric anaesthesia is most often performed with the help of a competent aide and this might encourage its implementation. Moreover, many presentations at meetings have emphasized that the use of cricoid pressure is a standard guideline and that this technique is widely used in teaching institutions. Surprisingly, though, its use was and still is much lower than in the UK [22] or New Zealand [17]. The various objections regarding the use of this technique have been summarized by Benhamou [23] and Brimacombe and Alison [24]. Conversely, many arguments remain in favour of the use of the Sellick's manoeuvre [25]. Studies are thus necessary to support its continuing use [25].

The use of succinylcholine doubled between 1988 and 1998 and is now used by one French team out of two for induction of Caesarean section. This is still a very low rate, although recent studies in the UK have shown that 66% of physicians use only succinylcholine in their practice and that trainees are more likely to use rocuronium than consultants [25]. This low rate of use in France can probably be accounted for by the increased risk of anaphylaxis with succinylcholine that has been very widely advertised by French investigators and is thus feared by many physicians [26]. Although special equipment for difficult intubation is available in almost all obstetric units, a written protocol is available in the operating theatre in only less than half of them. In Norway, a written protocol exists for only one team out of three as well [4].

Techniques for preventing aspiration in obstetrics were better implemented in academic units than in other hospitals; practice in university hospitals perhaps follows theoretical recommendations more closely. However, such significant differences of practices are seen neither in Norway nor in Canada [4,12].

In conclusion, this investigation reveals that a significant improvement in the French practice for preventing the aspiration syndrome occurred between 1988 and 1998. Regional anaesthesia and pharmacological prophylaxis are now widely used in Caesarean section patients. However, various elements can still be improved. The technique of rapid sequence induction is not always correctly employed in obstetrics since neither succinylcholine nor cricoid pressure is universally used. These data suggest that medical education should be continued and that surveys should be repeated at regular intervals.

References

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2. Benhamou D. French obstetric anaesthetists and acid aspiration prophylaxis. Eur J Anaesthesiol 1993; 10: 27-32.
3. Clergue F, Auroy Y, Pequignot F, Jougla E, Lienhart A, Laxenaire M. French survey of anesthesia in 1996. Anesthesiology 1999; 91: 1509-1520.
4. Soreide E, Holst-Larsen H, Steen PA. Acid aspiration syndrome prophylaxis in gynaecological and obstetric patients: a Norwegian survey. Acta Anaesthesiol Scand 1994; 38: 863-868.
5. Schneck H, Scheller M, Wagner R, von Hundelshausen B, Kochs E. Anaesthesia for cesarean section and acid aspiration prophylaxis: a German survey. Anesth Analg 1999; 88: 63-66.
6. Papiernik E, Zeitlin J, Milligan DWA, et al. Variations in the organization of obstetric and neonatal intensive care in Europe. Prenat Neonat Med 1999; 4 (Suppl 1): 73-87.
7. Warner MA, Warner ME, Weber JG. Clinical significance of pulmonary aspiration during the perioperative period. Anesthesiology 1993; 78: 56-62.
8. Ezri T, Szmuk P, Stein A, Konichezky S, Hagai T, Geva D. Peripartum general anaesthesia without tracheal intubation: incidence of aspiration pneumonia. Anaesthesia 2000; 55: 421-426.
9. Wright PM, Allen RW, Moore J, Donnelly JP. Gastric emptying during lumbar extradural analgesia in labour: effect of fentanyl supplementation. Br J Anaesth 1992; 68: 248-251.
10. Kelly MC, Carabine UA, Hill DA, Mirakhur RK. A comparison of the effect of intrathecal and extradural fentanyl on gastric emptying in laboring women. Anesth Analg 1997; 85: 834-838.
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17. Kluger MT, Willemsen G. Anti-aspiration prophylaxis in New Zealand: a national survey. Anaesth Intensive Care 1998; 26: 70-77.
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Appendix

Questionnaire on prophylaxis of aspiration of gastric contents in obstetric anaesthesia (please tick the appropriate box)

1. Where do you work?

(a) University teaching hospital □

(b) Community hospital □

(c) Private practice □

(d) Other □

2. Number of childbirths per year in your maternity department

(a) Less than 500 □

(b) Between 500 and 1000 □

(c) Between 1000 and 2000 □

(d) Between 2000 and 3000 □

(e) More than 3000 □

3. Do you believe that obstetric anaesthesia carries a particular risk of aspiration of gastric contents?

(a) Yes □

(b) No □

During labour

4. Do you believe that epidural administration of sufentanil or fentanyl slows gastric emptying?

(a) Yes □

(b) No □

(c) Don't know □

5. What is your feeding policy?

(a) Light meal □

(b) Fluids only □

(c) Nil by mouth □

6. Do you use regularly pharmacological prophylaxis to prevent acid aspiration syndrome?

(a) Yes □

(b) No □

7. If yes, which agent do you use?

(a) Effervescent cimetidine □

(b) Cimetidine p.o. □

(c) Cimetidine i.v. □

(d) Effervescent ranitidine □

(e) Ranitidine p.o. □

(f) Ranitidine i.v. □

(g) Sodium citrate only □

(h) Other (please specify ...) □

8. What is the technique of choice for analgesia?

(a) Epidural □

(b) Spinal □

(c) N2O □

(d) Other (please specify ...) □

In case of Caesarean section

9. Do you use regularly pharmacological prophylaxis to prevent acid aspiration syndrome?

(a) Yes □

(b) No □

10. If yes, which agent do you use?

(a) Effervescent cimetidine □

(b) Cimetidine p.o. □

(c) Cimetidine i.v. □

(d) Effervescent ranitidine □

(e) Ranitidine p.o. □

(f) Ranitidine i.v. □

(g) Sodium citrate only □

(h) Other (please specify ...........) □

In case of scheduled Caesarean section

11. What is the technique of choice for anaesthesia?

(a) Epidural □

(b) Spinal □

(c) Combined spinal-epidural □

(d) General anaesthesia □

In case of emergency Caesarean section

12. What is the technique of choice for anaesthesia if a functioning epidural catheter has been previously inserted?

(a) Epidural □

(b) Spinal □

(c) Combined spinal-epidural □

(d) General anaesthesia □

13. What is the technique of choice for anaesthesia if an epidural catheter is not inserted?

(a) Epidural □

(b) Spinal □

(c) Combined spinal-epidural □

(d) General anaesthesia □

General anaesthesia

14. Do you regularly use tracheal intubation if general anaesthesia is indicated for:

(a) Caesarean section

Yes □

No □

(b) Instrumental delivery

Yes □

No □

(c) Removal of retained placenta

Yes □

No □

In case of general anaesthesia for Caesarean section

15. Do you perform cricoid pressure?

(a) Yes □

(b) No □

16. If yes,

(a) When should cricoid pressure be started?

During induction □

After neuromuscular blocking agent has been injected □

During intubation □

(b) When should cricoid pressure be released?

After induction □

During intubation □

After tracheal cuff has been inflated □

17. Do you regularly insert a nasogastric tube?

(a) Yes □

(b) No □

(c) Sometimes □

18. Do you use the 'priming dose' technique?

(a) Yes □

(b) No □

(c) Sometimes □

19. Do you regularly use succinylcholine?

(a) Yes □

(b) No □

(c) Sometimes □

In case of difficult intubation

20. Do you have special equipment available in the obstetric suite?

(a) Yes □

(b) No □

21. Is there a written protocol describing the strategy in the obstetric suite?

(a) Yes □

(b) No □

Keywords:

ANAESTHESIA CONDUCTION, spinal, epidural; ANTI-ULCER AGENTS, antacids; NEUROMUSCULAR DEPOLARIZING AGENTS, succinylcholine; OBSTETRIC SURGICAL PROCEDURES, delivery, obstetric, Caesarean section; RESPIRATION, respiratory mechanics, aspiration, gastrointestinal agents

© 2004 European Academy of Anaesthesiology