Is low-dose propofol sedation safe in unfasted patients?

In recent years there has been renewed focus on improving the patient experience by avoiding or minimising preoperative fasting time.1Fawcett W.J. Thomas M. Pre-operative fasting in adults and children: clinical practice and guidelines.Anaesthesia. 2019; 74: 83-88Crossref PubMed Scopus (51) Google Scholar There is also anxiety that such changes may expose patients to an increased risk of aspiration. In a recent report in the British Journal of Anaesthesia, Guerrier and colleagues2Guerrier G. Rothschild P.-R. Bonnet C. et al.Safety of low-does propofol in non-faster patients undergoing cataract surgery: a prospective cohort study.Br J Anaesth. 2019; 123: e526-e528Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar describe a prospective cohort study in which 11 218 non-fasted adults underwent cataract surgery, with a subset of 2445 requiring procedural sedation by nurse-administered propofol under the direction of the surgeon. Of all patients included, 23% were ASA physical status 3 or 4. The authors report that there were no serious anaesthesia-related adverse events (namely gastric aspirations or desaturations below 92%), and that the incidence of posterior capsular disruption was similar (at 2%) in both the sedated and unsedated groups. The authors conclude that fasting guidelines for cataract surgery under conscious sedation might be revised. Nurse-administered propofol sedation and anaesthesia is a common practice globally, although there is still wide international variation in its acceptance.3Bosslet G.T. Devito M.L. Lahm T. Sheski F.D. Mathur P.N. Nurse-administered propofol sedation: feasibility and safety in bronchoscopy.Respiration. 2010; 79: 315-321Crossref PubMed Scopus (43) Google Scholar,4Pelosi P. Retraction of endorsement: European Society of Gastrointestinal Endoscopy, European Society of Gastroenterology and Endoscopy Nurses and Associates, and the European Society of Anaesthesiology guideline: non-anaesthesiologist administration of propofol for GI endoscopy.Endoscopy. 2012; 44: 302PubMed Google Scholar Unregulated administration by poorly trained staff still has the potential for significant harm.5Diaz J.H. Kaye A.D. Death by propofol.J La State Med Soc. 2017; 169: 28-32PubMed Google Scholar Current UK guidance is that propofol should be administered by anaesthetists for complex procedural sedation.6The Academy of Medical Royal Colleges Safe sedation practice for healthcare procedures: standards and guidance.2013https://www.aomrc.org.uk/reports-guidance/safe-sedation-practice-1213Date accessed: November 1, 2019Google Scholar The authors state that clear standard operating protocols were followed in all patients requiring administration of a small dose of oral midazolam before surgery. In addition, all patients had i.v. access established and were fully monitored. A nurse was instructed to administer a small dose of propofol (0.25 mg kg−1) after a request from the surgeon. Total (mean) propofol doses used were less than 30 (standard deviation [sd] 8) mg (not given in mg kg−1). Given that the recommended dose7British National Formulary. Propofol. BNF Propofol. Available from https://bnf.nice.org.uk/drug/propofol.html [Accessed 1 November 2019].Google Scholar for inducing procedural sedation is 0.5–1 mg kg−1, the doses used were unlikely to lead to loss of consciousness or loss of verbal contact consistent with general anaesthesia or deep sedation that might result in a loss of airway reflexes. Effect-site targeted propofol concentration by anaesthetist-controlled administration in the context of adult colonoscopies requires a mean (sd) propofol doses of 64 (32) mg initially, with a total dose of 288 (213) mg. With these doses it is possible to achieve observer assessment of alertness and sedation median (inter-quartile range) scores of 3 (1–5).8Stonell C.A. Leslie K. Absalom A.R. Effect-site targeted patient-controlled sedation with propofol: comparison with anaesthetist administration for colonoscopy.Anaesthesia. 2006; 61: 240-247Crossref PubMed Scopus (50) Google Scholar These are much larger doses than those used in this study, and although sedation scores are not provided, they are likely to be lower given the small mean dose of propofol used. Indeed, in the absence of validated sedation scores the reader is left to speculate as to the depth of sedation achieved. Given the minimal doses used, patients might have been hardly sedated at all. Nurse-administered sedation using a standard procedure has several attractions, however, it still requires highly trained staff adept in assessing consciousness levels with appropriate monitoring and effective prompt rescue pathways should complications arise.9Apfelbaum J.L. Gross J.B. Connis R.T. et al.Practice guidelines for moderate procedural sedation and analgesia 2018.Anesthesiology. 2018; 128: 437-479Crossref PubMed Scopus (209) Google Scholar Yet there is a large international variation in practice in the adoption of non-medically trained and non-anaesthesia trained staff. Whilst there are clear theoretical definitions that help describe the differences between sedation and anaesthesia, it can be much harder, in practice, to prevent straying from sedation into an anaesthetic state,10Hinkelbein J. Lamperti M. Akeson J. et al.European Society of Anaesthesiology and European Board of Anaesthesiology guidelines for procedural sedation and analgesia in adults.Eur J Anaesthesiol. 2018; 35: 6-24Crossref PubMed Scopus (115) Google Scholar although given the doses used, none of the patients in this study are likely to have been anaesthetised. Regardless of who is delivering the sedation, practitioners clearly need to be devoted to that task alone and be constantly vigilant to alterations in patient status. If done well, it can be a safe and effective practice,11Jensen J.T. Møller A. Hornslet P. Konge L. Vilmann P. Moderate and deep nurse-administered propofol sedation is safe.Dan Med J. 2015; 62: A5049PubMed Google Scholar but requires quality training and the ability to promptly recognise complications and escalate care. This is particularly the case when procedural sedation is the aim. Even when excellent regional or topical analgesia is provided, variations in surgical stimulus, large inter-individual variation in propofol requirements, and inter-individual variation in the physiological response to propofol mean that the artificial boundary between sedation and general anaesthesia becomes blurred. The reported crude anaesthetic outcome measures of aspiration and desaturation are thankfully rare events. Whilst almost 16 000 cases were included, only 2445 patients received propofol. With an incidence of aspiration of gastric contents of 1:900–100012Robinson M. Davidson A. Aspiration under anaesthesia: risk assessment and decision-making.Contin Educ Anaesth Crit Care Pain. 2014; 14: 171-175Abstract Full Text Full Text PDF Scopus (61) Google Scholar in adults, the claims of safety are premature. The median fasting for clear fluid of 81 min in the sedation group is consistent with newer fasting regimes being adopted for general anaesthesia in children,13Linscott D. SPANZA endorses 1-hour clear fluid fasting consensus statement.Paediatr Anaesth. 2019; 29: 292Crossref PubMed Scopus (12) Google Scholar,14Thomas M. Morrison C. Newton R. Schindler E. Consensus statement on clear fluids fasting for elective pediatric general anesthesia.Paediatr Anaesth. 2018; 28: 411-414Crossref PubMed Scopus (103) Google Scholar and also finding their way into adult practice.15McCracken G.C. Montgomery J. Postoperative nausea and vomiting after unrestricted clear fluids before day surgery: a retrospective analysis.Eur J Anaesthesiol. 2018; 35: 337-342Crossref PubMed Scopus (25) Google Scholar Much more concerning, however, is the breaching of currently accepted fasting recommendations for solids1Fawcett W.J. Thomas M. Pre-operative fasting in adults and children: clinical practice and guidelines.Anaesthesia. 2019; 74: 83-88Crossref PubMed Scopus (51) Google Scholar which have much greater potential for adverse aspiration outcomes in ASA physical status 3 and 4 patients and patients at high risk of delayed gastric emptying.16Mendelson C.L. The aspiration of stomach contents into the lungs during obstetric anesthesia.Am J Obs Gynecol. 1946; 52: 191-205Abstract Full Text PDF PubMed Scopus (939) Google Scholar,17Cook T. Woodall N. Frerk C. NAP4: executive summary.Difficult Airw Soc. 2011; 1–10 (Major complications of airway management in the United Kingdom. Report and findings March 2011)https://www.rcoa.ac.uk/sites/default/files/documents/2019-09/NAP4%20Full%20Report.pdfDate accessed: November 1, 2019Google Scholar It is potentially misleading to claim safety even for minimal sedation without sufficiently large numbers to assess other rare, but major anaesthetic adverse events. Surrogate markers of safety, such as no peripheral oxygen desaturations below 92%, cannot be used to substantiate the safety argument, but should merely serve as part of an indicator of observed minimum monitoring standards. Cardiac arrhythmias, hypertension, hypotension, the need for airway support, agitation, and loss of response to verbal command, for example, could all be reasonably added as triggers for escalation of care, measures of safe effective practice, or both. Many of these details are not provided in this study. It is perhaps not surprising that there were no reported cases of aspiration here. We know from recent work that fasting times do not seem to be a predictor for aspiration risk in a large cohort (almost 140 000) of children receiving a variety of anaesthetic and sedation techniques.18Beach M.L. Cohen D.M. Gallagher S.M. Cravero J.P. Major adverse events and relationship to nil per os status in pediatric sedation/anesthesia outside the operating room: a report of the Pediatric Sedation Research Consortium.Anesthesiol J Am Soc Anesthesiol. 2016; 124: 80-88Crossref PubMed Scopus (89) Google Scholar The overall rate of aspiration was low at less than one per 10 000 cases irrespective of whether they breached fasting guidelines or not, and this low rate seems to be similar in adult practice, even for emergency cases.19Thorpe R. Benger J. Pre-procedural fasting in emergency sedation.Emerg Med J. 2010; 27: 254-261Crossref PubMed Scopus (38) Google Scholar Reassuringly large denominators of this magnitude are needed to ensure adequate capture of rare events. It must also be recognised that the accepted definition of aspiration (inhalation of oropharyngeal or gastric contents into the larynx and respiratory tract) can be difficult to establish beyond doubt in the clinical setting. Coughing, desaturation, and laryngospasm are all surrogate signs for this complication. Anaesthetists are best placed to lead the education and training in safe sedation by non-anaesthetic practitioners. Failure to do so may lead to repeated large audits by surgical, medical, or allied health professionals with variable quality practices, inconsistent outcome measures, and a variety of claims of safety. The recent report by Guerrier and colleagues2Guerrier G. Rothschild P.-R. Bonnet C. et al.Safety of low-does propofol in non-faster patients undergoing cataract surgery: a prospective cohort study.Br J Anaesth. 2019; 123: e526-e528Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar suggests that minimal sedation does not result in increased aspiration risk in this patient cohort but, as the authors themselves conclude, is too small to be definitive. By clearly defining the adverse outcomes of interest, looking for them in large enough cohorts, and having rapid escalation protocols, we can evaluate the true risks and benefits to patients that low-dose propofol might have, and thus help us determine whether or not it is safe. Combining large databases of electronic patient records both within and between hospitals may be the future direction of such safety work if sufficiently large denominators are to be achieved. MT and TE are both section editors of Paediatric Anaesthesia. TE is associate editor of the British Journal of Anaesthesia and editor of Acta Anaesthesiologica Scandinavica. Safety of low-dose propofol in non-fasted patients undergoing cataract surgery: a prospective cohort studyBritish Journal of AnaesthesiaVol. 123Issue 6PreviewEditor—Cataract surgery is the most frequently performed surgery in the developed world, with low morbidity and mortality.1 Minimally invasive phacoemulsification is usually performed under topical anaesthesia in conscious patients. Inadvertent patient movement induced by pain or anxiety can negatively affect surgical outcomes. Topical anaesthesia without sedation may not be adequate for anxiety control in highly stressed patients during cataract surgery; adequate sedation might play an important role in the operative experience for both patients and surgeons. Full-Text PDF Open Archive