East Anglian Endoscopy Database Study PaperDocument Transcript
1Sedation for Gastrointestinal Endoscopic Procedures in the Elderly:Getting Safer but Still Not Nearly Safe EnoughLord DA1, Bell GD1, Gray A2, Quine A3, Bowles J4, Improvements have occurred in the use of pulseRomaya C5, de la Iglesia B1, Reynolds A1, Rayward- oximetry, supplemental oxygen and continuousSmith VJ1 intravenous access. Mean doses of benzodiazepines and opiates given for GISummary endoscopy sedation in the elderly still exceed published guidelines, although doses have fallenBackground significantly since the 1990’s. The use ofPreviously published UK reports showed that flumazenil, a specific benzodiazepine antagonist,excessively large doses of benzodiazepines and appears to be a good marker of over-sedation andopiates were being commonly used to sedate cardiopulmonary complications were moreelderly patients for gastrointestinal (GI) common in patients who were given the drug. Inendoscopy. This unsafe practice has lead to the NCEPOD study of patients who died withinavoidable morbidity and mortality. We have 30 days after therapeutic endoscopy, the timetaken the opportunity provided by recent reports between endoscopy and death was significantlyto examine whether GI endoscopy sedation shorter in those who received flumazenil. In thepractice in the elderly has improved in the light East Anglian study, there was a two-fold differenceof this evidence and the publication of guidelines in the average doses of both midazolam andin which specific recommendations on sedation pethidine used by individual endoscopists in elderlydosage are given. patients. Despite the well-known synergism between opioids and benzodiazepines, worryingly,Methods those endoscopists who used the highest averageUsing data mining techniques, we have extracted doses of midazolam in elderly patients also tendeddata on the use of benzodiazepines and opiates to be those who administered the largest amountsfrom a recent NCEPOD report on deaths of pethidine.following GI therapeutic endoscopy and fromunpublished data from six East Anglian hospital InterpretationGI endoscopy databases. We have compared Patient safety would be significantly improved ifand contrasted these data with re-analysed data those GI endoscopists who regularly givefrom two previously published large audits of unnecessarily high doses of sedative and analgesicupper and lower GI endoscopy carried out in drugs to elderly patients changed their sedation1991 and 1998 respectively. practice to conform to published guidelines. Regular audit of sedation dosages and reporting ofFindings ‘near misses’ (including flumazenil usage), isMidazolam has largely replaced diazepam as the recommended.benzodiazepine of first choice and many moreprocedures are now carried out without sedation. Introduction It was well established over 25 years ago that elderly patients are particularly sensitive to the1 School of Computing Sciences, UEA, Norwich CNS depressant effects of oral benzodiazepines2 NCEPOD such as diazepam, chlordiazepoxide,3 Queen Alexandra Hospital, Portsmouth flurazepam  and nitrazepam. Although4 Royal Free Hospital, London pharmacokinetic differences are undoubtedly5 British Society of Gastroenterology
2contributory, the evidence suggests that et al. Despite this, and a small reduction in thepharmacodynamic factors are much more mean doses of sedative and analgesic drugs beingimportant when explaining the marked employed in the more recent audits[20, 21], there havedifferences in benzodiazepine CNS sensitivity been, once again, a number of reported sedation-between the young and old. Based on these and related cardiopulmonary deaths in elderly patients.other studies[1-5], it has been standard clinical A 2004 report by the National Confidentialpractice in the elderly to prescribe half (or less) of Enquiry into Patient Outcome and Deaththe dose of hypnotics such as nitrazepam and (NCEPOD), “Scoping our Practice”, found thatflurazepam that would normally be prescribed to there had been 1,818 deaths after therapeutic GIyounger patients. endoscopic procedures. NCEPOD advisors judged that the sedation given was inappropriate inMidazolam has gradually replaced diazepam as 14% of cases, usually because an overdose ofthe IV sedative of choice for most benzodiazepine had been administered.gastrointestinal (GI) endoscopic procedures[6, 7].As with orally administered benzodiazepines[1-3, 5], We decided to re-analyse the NCEPODintravenous (IV) midazolam dosage needs to be therapeutic endoscopy data in terms of sedationreduced dramatically in the elderly, especially if practice and to compare and contrast the resultsa bolus technique is employed. IV midazolam withand diazepam can both depress respiration andcause marked hypoxia[10, 11]: hence the need for a) the 1991 Upper GI Auditpulse oximetry, supplemental oxygen[12, 13] and the b) the 1998 Colonoscopy Auditready availability of the benzodiazepine c) a current six hospital East Anglian Study.antagonist, flumazenil[13, 14]. Our results show that many endoscopists areMonitoring and safety guidelines for sedating persisting in using unnecessarily large doses of IVpatients have been issued in the past[13, 15, 16]; sedative and analgesic drugs in elderly patients withparticularly in light of a 1991 UK audit of over potentially fatal consequences. We make14,000 patients undergoing an upper GI recommendations regarding drug dosage andendoscopy. The 1991 audit, published in 1995, clinical practice based on these findings.found that over 100 patients died within 30 daysof the procedure. Several of these patients died Patients, Materials and Methodsas a result of being given too large a dose ofeither IV midazolam or diazepam. Similar NCEPOD Therapeutic Endoscopy Reportcases of sedation-related deaths have been This report studied 1,818 patients who died inreported elsewhere[18, 19]. hospital within 30 days of having undergone a therapeutic endoscopic procedure in England,Previous guidelines[13, 15, 16] have all stressed the Wales, Northern Ireland, Guernsey, the Isle ofimportance of not exceeding the dose of IV Man, the Defence Secondary Care Agency andbenzodiazepine recommended by the hospitals within the independent sector. Data wasmanufacturer and of reducing the dose requested for the period of one year from 1st Aprilsufficiently in elderly, frail or at-risk patients. 2002 to 31st March 2003. These procedures included oesophageal dilatation, oesophageal stentMore recent audits of endoscopic procedures insertion, injection of oesophageal varices,such as colonoscopy and Endoscopic Percutaneous Endoscopic Gastrostomy (PEG),Retrograde Cholangiopancreatography (ERCP) ERCP and a number of lower GI therapies such ashave shown improved use of pulse oximeters, polypectomy and colonic stenting. As described insupplemental oxygen and indwelling IV cannulae detail in the report, the 1,818 patients who diedwhen compared with the earlier report of Quine
3probably represents about 3 % of the total and database. With the permission of their IT,number of patients undergoing a therapeutic medical and nursing staff, a member of the medicalendoscopic procedure during the time of data-mining group visited the hospital and took aobservation. The anonymised database of the copy of the Endoscribe/HCNscribe database.original report from NCEPOD was re-analysedby the medical data-mining group from the The databases from each of the hospitals were pre-School of Computing Sciences at the University processed (correcting data errors, removingof East Anglia (UEA). incomplete records and validating field entries). The hospitals and individual endoscopists wereUpper GI Endoscopy Audit each given a code and the data was anonymised.In the four-month period from February to June The databases were transformed into a new data1991 3,956 upper GI endoscopies were structure more suited to statistical analysis and dataperformed in the UK by the East Anglian Health mining[24-26] and then combined into one database.Region, (an estimated 5.76 Data from the Upper GI audit, the Colonoscopygastroscopies/1000/year) and in the four-month audit and the NCEPOD audit were each processedperiod from April to August 1991, there were in the same way to allow a truer comparison10,193 examinations carried out by the North between the four studies.West Health Region, (8.8/1000/year). The totalnumber of procedures performed was 14,149 of Statistical Analysiswhich 13,036 (92%), were diagnostic and the For each of the four above databases, we looked atremaining 8% were therapeutic. The audit the mean, median and 95% confidence limitsincluded a 30-day post endoscopy period to study around the doses of the different IV sedative andboth morbidity and mortality. The anonymised analgesic drugs used in the different patient agedatabase used for the original report was groups. We also looked at the pattern of use of theprovided for our use by the British Society of benzodiazepine antagonist, flumazenil as aGastroenterology (BSG). surrogate marker of a patient having inadvertently been given an excessive dose of either midazolamColonoscopy Audit or diazepam. Analysis was carried out usingOver a four-month period in 1998, there were algorithms in SQL and PL-SQL, Oracle Data9,223 colonoscopies carried out in three Regions Miner and with the Arcus QuickStat statistical(North East Thames, East Anglia and West software.Midlands). As in the upper GI audit, there was a30-day post colonoscopy period to study both Resultsmorbidity and mortality. The anonymiseddatabase used for the original report was again NCEPOD Therapeutic Endoscopy Reportprovided for our use by the BSG. This report studied 1,818 patients who died in hospital within 30 days of having undergone aEast Anglian Endoscopy Database Study therapeutic endoscopic procedure. In 1,326/1,818,The Endoscopy Units of the following hospitals or 72.9% of cases, midazolam was used. Inin East Anglia were included in the study: 1,294/1,326 or 97.6%, the actual dose ofNorfolk and Norwich University Hospital, midazolam was recorded. Flumazenil wasCromer Hospital, Queen Elizabeth Hospital at prescribed in 160/1294 or 12.4% of patients givenKing’s Lynn, North Cambridgeshire Hospital at midazolam where the dosage was known and inWisbech, the James Paget Hospital at Great 5/32 or 15.6% of cases where the dose ofYarmouth and the Ipswich Hospital. All these midazolam was not recorded. Diazepam was usedunits used either Endoscribe or HCNscribe in only 69/1,818 or 3.8% of cases. Flumazenil wassoftware as their Endoscopy reporting system prescribed in 8/69 or 11.6% of patients given
4diazepam. In all but two of the cases having Lowereither midazolam or diazepam, the use of ERCP PEG Upper GI GIflumazenil was unplanned and the indication Mean (SD) 5.1 (2.9) 3.3 (1.5) 3.9 (2.3) 3.2 (1.5)stated to be to reverse excessive sedation e.g. Midazolam doserespiratory depression or loss of verbal contact. Significance vs. p<0.0001 p<0.0001 p<0.0001 ERCP (Midazolam)NCEPOD - Dose of Midazolam and Number (%) given 35/177 64/566 62/521 1/30Pethidine Used – with and without Flumazenil (19.8) (11.3) (11.9) (3.3)Flumazenil being required Significance vs. p=0.0052 p=0.0117 p=0.0034 ERCP (Flumazenil)The mean age of the 160 patients givenflumazenil (where the dose of midazolam was Table 2. Use of flumazenil in the NCEPOD study. Flumazenil wasrecorded) and the 1,134 who did not receive used significantly more frequently during or after an ERCP than anyflumazenil was in both cases 78.4 years of age. other procedure.As shown in Table 1, the mean dose ofmidazolam was significantly higher in the patients NCEPOD – Critical Incidents during thewho received flumazenil (p=0.0034). Endoscopic ProcedureSignificantly more midazolam patients who In all 93% (1,688/1,818) responded to the questionrequired flumazenil also had the opioid pethidine relating to critical events. Cardiorespiratory critical(p<0.05) administered in a dose that was incidents during therapeutic endoscopy weresignificantly higher (p=0.0074) than when relatively frequent. In total, from 73 patients therereversal was not required. were nine cardiac arrests, 7 respiratory arrests and 62 reported incidents of clinically significant Flumazenil Flumazenil hypoxia. If a cardiac arrest, respiratory arrest or Drug (mg) Used Not Used Significance hypoxic incident was reported then flumazenil wasMidazolam 4.3 (2.7) 3.7 (2.1) p=0.0034 given in significantly more cases than when no such critical episode was reported: 27/73 or 37.0%Pethidine 46.0 (14.6) 38.0 (13.9) p=0.0073 vs. 125/1,615 or 7.7% (p<0.0001).Table 1. Mean (SD) dose of midazolam and pethidine used in theNCEPOD study – with and without flumazenil being required. NCEPOD – Time to Death after the Endoscopic Procedure and the Effect ofThe mean dose of midazolam varied with the Having Required Sedation Reversal withtherapeutic GI procedure performed. The mean Flumazenildose of midazolam used for ERCP patients was, In the NCEPOD database, it was possible toin all age groups, significantly greater (p<0.001) calculate the time in days from the endoscopicthan either the therapeutic Upper or PEG group procedure to death for 1,789 patients. In this(see table 2). Predictably therefore, flumazenil group, there were 173 patients who receivedwas required significantly more frequently to flumazenil and 1,616 patients who did not. Thosereverse the adverse effects of midazolam sedation given flumazenil died on average two days earlierduring or following an ERCP than PEG insertion than those not given the reversal agent (p<0.05).(p=0.0052) or either a GI therapeutic upper(p=0.0117) or lower (p=0.0034) endoscopic As shown above, the ERCP group received theprocedure (table 2). largest doses of midazolam and had the highest percentage flumazenil usage. When the ERCP group was considered separately, (see figure 1) the median time to death was on average four days earlier when flumazenil had been used than when it was not required (p=0.0108).
5 Figure 2. Each data point represents a single dose of midazolamFigure 1. A ‘box and whisker’ plot shows that patients undergoing administered by an individual endoscopist to a patient over the age of 90an ERCP examination on average died 4 days earlier when years. It can be seen that those claiming to have had previous training influmazenil was required to reverse their midazolam sedation when sedation techniques (red symbols) used no less sedation than those whocompared with those whose sedation did not require reversal. had not been specifically trained (blue symbols).NCEPOD – Effect of Endoscopist’s Previous Upper GI Endoscopy AuditSedation Training on the Sedation Dose and In East Anglia and the North West, 86% (3,405)use of Flumazenil and 84% (8,593) of upper GI endoscopies wereIn all, for 634 of the patients involved in the performed with some form of intravenous sedationNCEPOD study, the endoscopist stated that they plus or minus local anaesthetic. In all, midazolamhad had previous training in sedation techniques. was used in 52.5% of cases and diazepam (mainlyWhile in 1,171 of the patients, the endoscopists in the form of Diazemuls) was given to 47.5% ofconducting the examination indicated they had patients. At the time of this audit, diazepam wasnot received specific training in sedation. There the preferred intravenous sedative in East Angliawas no difference in either the dose of (used in 59 % of all patients sedated) whereas inmidazolam (means both 3.8 mg) or pethidine the North West Region more endoscopists(mean dose of 36.2 mg and 39.2 mg respectively) favoured midazolam (57% of all patients sedated).in the sedation ‘trained’ and ‘untrained’ groups.Similarly, flumazenil requirements to reverse The mean dose of diazepam used for sedation inexcessive sedation were very similar at 67/644 or the two regions was 13.5 mg, (East Anglia) and10.4% and 109/1172 or 9.3% respectively in the 14.0 mg, (North West) and for midazolam, the2 groups. Just how high the doses of midazolam mean dose was 5.7 mg in both regions. Theadministered were on occasion is illustrated in distribution of dosages used in both regions wasfigure 2. It can be seen that sedation training equally wide; maximum doses of diazepam andmade no difference to the dose of drug midazolam used were 50 mg and 30 mgadministered to patients over the age of 90. respectively. The mean dose of both midazolam and diazepam given decreased with advancing age (see table 3), but for each age group the dose given to individual patients varied enormously.
6Age Upper GI Colon East mentioned above) who subsequently were givenGroup Audit Audit NCEPOD Anglian flumazenil (see figure 3). It can be seen thatUnder 20 6.7 (3.1) 8.0 (4.0) 4.9 (1.7) flumazenil use was both dose and age-related and20-29 7.1 (3.1) 6.5 (3.7) 4.7 (1.5) increased dramatically after 70 years of age.30-39 6.7 (2.8) 6.3 (4.1) 4.7 (1.4) Reported Use of Flumazenil at OGD - Effect of Age40-49 6.7 (2.7) 6.0 (3.2) 4.5 (1.4) 35.050-59 6.0 (2.5) 5.8 (3.2) 4.0 (n=4) 4.4 (1.4) 30.060-69 5.4 (2.1) 5.4 (3.0) 2.0 (n=2) 4.0 (1.3) % Given Flum azenil 25.070-79 4.6 (2.0) 4.9 (2.1) 4.8 (1.9) 3.5 (1.3) 20.080-89 4.0 (1.9) 4.2 (1.9) 2.7 (0.9) 3.1 (1.2) 15.090 plus 4.3 (2.4) 3.4 (1.4) 2.7 (0.6) 2.6 (1.0) 10.0 5.0Table 3. Mean (SD) dose of midazolam used in patients of different 0.0age groups in the four different audits discussed in the present paper. Under 20 20 to 29 30 to 39 40 to 49 50 to 59 60 to 69 70 to 79 80 Plus AgeUpper GI Endoscopy Audit - relationship 10 mg Diazemuls 20 mg Diazemuls 5mg Midazolambetween the dose of diazepam or Midazolamadministered and the use of Flumazenil Figure 3. Relationship between the age of patient and reported use of flumazenil when a 10 mg or 20 mg dose of diazemuls or a 5 mg dose ofFlumazenil was used in 382/11,896 or 3.2% of all midazolam was given.cases sedated with either midazolam or diazepam.Patients in the NW Region received flumazenil in 1998 Colonoscopy Audit4% of cases compared with 2% in East Anglia. In this study in three Health Regions carried outThis difference was almost entirely due to the over a four-month period in 1998, 73 Endoscopyfact that two centres in the NW (who contributed units prospectively audited their colonoscopic189 and 92 patients respectively) were at that practice plus 30-day morbidity and mortalitytime using flumazenil routinely in all patients figures. In all 9,223 colonoscopies werebeing sedated with midazolam. If these two performed. In 94.6%, some form of sedation wascentres are excluded, then 290/11,513 or 2.5% of used. When sedation was used, midazolam wassedated patients had flumazenil reversal. given in 88.6% of cases and diazepam (as Diazemuls) in 11.4%. The most common was aThe mean dose of Diazemuls was 18.9 mg when combination of pethidine and midazolam (57.8%flumazenil was also given compared 13.1 mg of colonoscopies). The mode dose of midazolamwhen it was not (p<0.0001). Excluding the two was 5.0 mg (range 0.5 - 20 mg) while that ofunits where Flumazenil was given routinely to all Diazemuls was 10 mg (range 1.0 - 30 mg). Thepatients, the mean dose of Midazolam when mode dose of pethidine was 50 mg (range 10 - 100Flumazenil was also given was 5.8 mg compared mg). The mean dose of midazolam was 5.8 mgto 5.7 mg without (p=0.172) while that of Diazemuls was 13.2 mg. The mean dose of pethidine was 48.3 mg.In 1991, many endoscopists in both Regionstended to use the same dose of diazepam or Colonoscopy Audit - Relationship between themidazolam irrespective of patient age or ASA Dose of Midazolam given and Flumazenil usestatus. We were thus able to look at the Flumazenil was used in 3.4% of patients. In thepercentage of patients in different age groups vast majority of these cases, this was to reversereceiving a) 10 mg of diazepam b) 20 mg of excessive benzodiazepine sedation. Althoughdiazepam or c) 5 mg of midazolam (again there was a small reduction in the maximumexcluding the two groups from the NW sedation dosages used when compared with the
7Quine audit, mean dosages for midazolam Number ofwere very similar. There were still many Hospital Procedures Period Coveredendoscopists using the same dose of midazolam A 28 184 Feb 2002 – Sep 2004(most often 5 mg) in all age groups. We were B 15 957 Mar 2001 – Jun 2004thus able to look at the percentage of patients in C 19 913 Jan 2000 – Feb 2005different age groups receiving 5 mg of midazolamwho subsequently required reversal with D 12 855 Jan 2000 – Aug 2005flumazenil (see figure 4). It can be seen that, as E 9 908 Jan 2000 – Aug 2005in the Quine study (see figure 3), flumazenil Total 86 817usage increased markedly after the age of 70 yearsof age. Table 4. East Anglian study, Number of procedures and the period covered, by hospital. Midazolam 5 mg - Colonoscopy Fewer endoscopists were still using diazepam (mainly in the form of Diazemuls). Only 8.9% of 9 8 Percentage Given Flumazenil 7 all sedated endoscopic procedures were carried out 6 5 using diazepam. These were mainly performed by 4 just two endoscopists (who contributed 3,354 and 3 2 982 cases respectively). The mean (SD) dose of 1 diazepam used in all patients was 9.3 (2.1) mg, 0 Under 20 20 to 29 30 to 39 40 to 49 50 to 59 60 to 69 70 to 79 80 Plus while in the case of OGD and colonoscopy it was Age 9.2 (2.4) mg and 9.4 (1.8) mg respectively. These East Anglian Study Colonoscopy Audit diazepam doses were significantly less than in the 1991 upper GI and 1998 colonoscopy audits whenFigure 4. Relationship between the age of patient and reported use of the figures were 14.0 (11.0) mg and 13.2 (6.8) mgflumazenil when a 5mg dose of midazolam was administered. The (p<0.0001 and p<0.0001 respectively). In the casegraph also shows comparable data from the East Anglian Study. of the 91.1% of sedated patients who were sedatedEast Anglian Endoscopy Database Study with midazolam, the mean (SD) dose of midazolam used in all patients was 3.9 (1.4) mg,The number of Endoscopy reports collected while in the case of OGD and colonoscopy it wasfrom each hospital and the time-period over 3.8 (1.4) mg and 3.9 (1.3) mg respectively. Thesewhich the data was collected is given in table 4. doses were significantly less than in the 1991 upperIn total, the combined database included 51,609 GI and 1998 colonoscopy audits, where theupper GI endoscopies (of which 4,161 where comparative figures were 5.6 (2.6) mg and 5.8 (3.1)therapeutic), 2,406 ERCPs, 1,061 PEGs and mg (p<0.0001 and p< 0.0001 respectively).19,050 colonoscopies. For upper GI endoscopy,the percentage of patients who had their The mean doses of midazolam and pethidine usedprocedure performed without any IV sedation in the different age groups of patients in Eastwas 20,138/ 51,609 or 39 %. This figure is Anglia for procedures such as PEG tubesignificantly greater (p<0.0001) than the figure of placement, ERCP, colonoscopy and therapeutic1,841/13,737 or 13.4% reported in the 1991 upper GI Endoscopy are shown in tables 5 to 9.OGD audit of Quine et al. For purposes of comparison, the same tables contain the data calculated from a) the Quine audit of OGD b) the Bowles colonoscopy audit and c) NCEPOD report.
8 Age Group NCEPOD - PEG East Anglian - PEGAge Upper GI Colon East NCEPODGroup Audit Audit Anglian Under 20 4.4 (3.0)< 20 50.0 (n=4) 52.4 (18.7) 45.5 (11.8) 20-29 3.5 (0.5) 3.9 (1.1)20-29 50.0 (13.8) 51.1 (12.6) 48.6 (10.2) 30-39 3.9 (0.9) 4.3 (1.3)30-39 60.6 (24.0) 50.2 (12.1) 48.4 (10.5) 40-49 4.3 (3.2) 5.0 (2.0)40-49 54.1 (24.6) 49.4 (12.1) 48.1 (10.8) 50-59 5.2 (1.8) 4.1 (1.6)50-59 47.5 (12.5) 48.9 (10.1) 50.0 (n=1) 46.6 (10.9) 60-69 3.5 (1.2) 3.8 (1.4)60-69 47.9 (13.1) 47.8 (9.8) 40.0 (n=1) 44.2 (11.6) 70-79 3.3 (1.4) 3.4 (1.3)70-79 46.2 (12.6) 46.1 (10.6) 41.7 (11.8) 40.9 (12.5) 80-89 3.0 (1.3) 2.9 (0.9)80-89 37.8 (14.9) 40.7 (12.5) 35.7 (12.4) 38.7 (12.6) 90 plus 2.9 (1.0) 2.4 (0.9)90 plus 41.3 (13.4) 43.8 (10.8) 20.9 (5.9) 35.1 (12.3) Table 7. Mean (SD) dose of midazolam used in PEG patients of different age groups in both the East Anglian audit and the Table 5. Mean (SD) dose of pethidine used in patients of different NCEPOD report.age groups in the four different audits discussed in the present paper. Age group NCEPOD East Anglian Colon Audit Mean (SD) Midazolam Mean (SD) PethidineAge Under 20 5.0 (1.6) 8.0 (4.0)Group East East NCEPOD NCEPOD 20-29 4.6 (1.5) 6.5 (3.7) Anglian AnglianUnder 20 8.5 (2.2) 55.6 (15.7) 30-39 4.5 (1.3) 6.3 (4.1)20-29 7.2 (2.6) 54.3 (12.7) 40-49 4.4 (1.3) 6.0 (3.2)30-39 12.5 (2.5) 7.2 (2.3) 50.0 (n=2) 56.5 (18.9) 50-59 4.0 (n=4) 4.2 (1.2) 5.8 (3.2)40-49 6.2 (2.1) 52.7 (12.9) 60-69 2.0 (n=2) 3.9 (1.2) 5.4 (3.0)50-5 7.4 (3.3) 5.9 (2.2) 41.7 (11.8) 52.6 (13.3) 70-79 4.8 (1.9) 3.5 (1.2) 4.9 (2.1)60-69 6.4 (4.0) 5.4 (1.8) 45.6 (9.6) 50.2 (10.9) 80-89 2.7 (0.9) 3.1 (1.2) 4.2 (1.9)70-79 5.3 (2.5) 4.8 (1.9) 41.9 (11.9) 47.9 (10.9) 90 plus 2.7 (0.6) 2.6 (0.8) 3.4 (1.4)80-89 4.4 (2.0) 4.1 (1.4) 33.1 (16.2) 43.9 (11.1) Table 8. Mean (SD) dose of midazolam used in colonoscopy in patients90 plus 3.7 (1.8) 3.6 (1.2) 33.8 (13.8) 39.0 (12.5) of different age groups in the East Anglian study, colonoscopy audits and the NCEPOD report.Table 6. Mean (SD) dose of midazolam and pethidine used inERCP patients of different age groups in both the East Anglian Age group NCEPOD East Anglian Colon Auditstudy and the NCEPOD report. Under 20 46.3 (10.8) 52.4 (18.7) 20-29 48.7 (9.7) 51.1 (12.6) 30-39 48.1 (9.9) 50.2 (12.1) 40-49 47.9 (10.5) 49.4 (12.1) 50-59 50.0 (n=1) 46.3 (10.8) 48.9 (10.1) 60-69 40.0 (n=1) 43.8 (11.4) 47.8 (9.8) 70-79 41.7 (11.8) 40.5 (12.3) 46.1 (10.6) 80-89 35.7 (12.4) 37.3 (12.6) 40.7 (12.5) 90 plus 20.9 (5.9) 32.3 (11.2) 43.8 (10.8) Table 9. Mean (SD) dose of pethidine used in colonoscopy in patients of different age groups in the East Anglian study, colonoscopy audits and the NCEPOD report.
9East Anglian Study - relationship betweenthe dose of midazolam administered and theuse of flumazenilIn the 49,681/86,817 patients, who were sedatedwith midazolam for any procedure, the overallpercentage recorded as subsequently being givenflumazenil was 0.8%. The figures for upper GIendoscopy, PEG insertion, ERCP andcolonoscopy were 0.9%, 3.2%, 1.8% and 0.6%respectively. In all patients given exactly 5mg ofmidazolam, the relationship between age andpercentage recorded as having been given Figure 6. Shows a 2.5 fold variation in the dosage of midazolam that aflumazenil is shown in figure 5. patient over the age of 70 can expect to receive depending on which endoscopist administers the sedation. Each data point represents the Midazolam 5 mg - All Procedures average dose of midazolam in mg given to patients over the age of 70 years by different individual endoscopists in either hospital A (red 2.5 symbols) or hospital B (blue symbols). Percentage Given Flumazenil 2 1.5 1 0.5 0 Under 20 20 to 29 30 to 39 40 to 49 50 to 59 60 to 69 70 to 79 80 Plus AgeFigure 5. Relationship between the age of patient and reported use offlumazenil when a 5mg dose of midazolam was administered for anyprocedure.East Anglian Study – Individualendoscopist’s variation in average dose ofmidazolam and pethidine prescribed in Figure 7. Shows a two-fold variation in the dosage of pethidine that apatients over the age of 70 years patient over the age of 70 can expect to receive depending on which endoscopist administers the sedation. Each data point represents theWe noted a 2.0 - 2.5 fold variation in the mean average dose of pethidine in mg given to patients over the age of 70 yearsdose of both midazolam and pethidine being by different individual endoscopists in either hospital A (red symbols) orused by different individual endoscopists to hospital B (blue symbols).sedate their elderly patients. These differenceswere particularly marked in the case of patients In order to see if those colonoscopists who wereundergoing colonoscopy. Typical results from using a relatively large average dose of midazolamhospital A and B are shown in figures 6 and 7. were compensating by using a smaller dose of pethidine (or vice versa), we correlated each colonoscopists mean dose of midazolam with their mean dose of pethidine in the over 70 year old group. As can be seen from the example data from one large hospital shown in figure 8, the
10results showed just the opposite. Those situation. In those patients who were given an IVendoscopists using larger mean dosages of dose of a benzodiazepine, midazolam was used inmidazolam were also frequently the same 95% of cases while diazepam was employed in justendoscopists who administered relatively high 5% of patients. Detailed analysis therefore wasdoses of pethidine (p=0.0135). concentrated on midazolam usage. The mean dose of midazolam given when flumazenil was required was significantly higher than that when reversal Hospital A - Over 70 Year Olds was not needed. Predictably, bearing in mind the well-known synergism between benzodiazepines 5.0 and opioids, flumazenil was also required significantly more frequently when midazolam was Mean Midazolam Dose (mg) 4.0 combined with pethidine. 3.0 Patients who needed to have their midazolam 2.0 reversed were more likely to a) have a critical event 1.0 such as significant hypoxia leading in certain cases to cardiopulmonary arrest during their endoscopy 0.0 and b) die on average two days earlier than 0.0 10.0 20.0 30.0 40.0 50.0 Mean Pethidine Dose (mg) comparable patients not requiring flumazenil. It was of interest that the patients undergoing an ERCP examination:Figure 8. Hospital A - Shows the relationship between the meanmidazolam dose and the mean pethidine dose given by individualendoscopists (who performed at least ten procedures) to patients over i) had the largest doses of sedationthe age of 70 years of age. ii) required flumazenil significantly more frequently that other groupsDiscussion iii) died, on average, four days earlier whenAs the NPSA (National Patient Safety reversal was requiredAssociation) points out, the medical profession isnotoriously slow to learn from its mistakes and It has previously been shown that, as for oral‘near misses’. A new report from the National benzodiazepines[1-5], elderly patients require only aAudit Office(NAO) entitled ‘A safer place for fraction of the dose of midazolam needed by fitpatients: learning to improve patient safety’ young adults. Most endoscopists in the UKaccepts that there is significant under-reporting administering IV sedative plus or minus anof deaths and serious incidents within the NHS. analgesic drug use a bolus injection over a fewThe NAO estimates that 22% of incidents, many seconds rather than the more correct slow titrationof which are medication errors, still go method. In this situation, even more dramaticunreported and agrees with the NPSA that ‘near reductions in dosage are required[9, 30].misses’ are rarely acted upon. The BSG, in its most recent guidelines on sedationNCEPOD Study and safety published in Sept 2003, madeOur results taken from the NCEPOD report recommendations regarding dosage of midazolamclearly show that, if elderly patients are given an and pethidine. In the case of patients over theIV benzodiazepine in the sort of doses that are age of 70 years, the BSG suggests an average dosemore appropriate for fit young adults, then their of no more than 2 mg of midazolam while in a fitsafety is endangered. In the NCEPOD study, the young adult a dose of 5 mg might be morebenzodiazepine antagonist flumazenil was almost appropriate. Should an opioid such as pethidine beentirely given to attempt to reverse an overdose required, as it frequently is for procedures such as ERCP or colonoscopy, then the BSG recommends
11that the opioid be given first and then the administration as a surrogate marker of increasingbenzodiazepine given slowly and cautiously. In sensitivity to the drugs in the elderly. The shape ofthe case of pethidine, the BSG has suggested an the curves shown in figure 3 with a rapid rise in theaverage dose of no more than 25 mg in a patient incidence of side effects in the over 70 year old ageover the age of 70 years of age and no more than group are remarkably similar to those reported by50 mg for a fit young adult. Greenblatt et al back in 1977. As in that earlierBearing in mind the fact that the mean age of study, we have shown that there are clear dose andpatients in the NCEPOD Therapeutic age related effects associated with givingEndoscopy study was 78.4 years and that some unnecessarily large doses of IV benzodiazepines to80% were classed as being ASA grade 3, the elderly patients.doses of midazolam and pethidine given to manypatients (table 1 and figure 2) were clearly East Anglian Studyexcessive. Diazepam, in the form of diazemuls, is now only rarely employed by endoscopists in East AngliaUpper GI Endoscopy and Colonoscopy with only 3.5% of endoscopists still regularly usingAudits it. Unlike the situation in 1991, midazolam is nowComparing the two audits shows a significant the preferred benzodiazepine by the overwhelmingimprovement over time in terms of reduction in majority of endoscopists. Many more patients aremean diazepam but not midazolam drug dosage. now asking to have their upper GI endoscopiesThere was also a marked increase in the use of performed without using any IV sedation than wassuch measures as pulse oximeters, supplemental the case 15 years ago. Furthermore, as shown inoxygen and indwelling IV cannulae. The fact that tables 5 to 9, the doses of midazolam andthe procedure related mortality, 1:2,000 for upper pethidine currently in use are certainly significantlyGI endoscopy and 1:1,500 for colonoscopy, was less than those used in 1991 or even 1998. Manynot improved was disappointing. elderly patients having both diagnostic as well as therapeutic procedures, however, are still beingOver 100 of the 14,000 patients in the upper GI given doses of sedative and analgesic drugs that areaudit died within 30 days of the procedure. well in excess of BSG guidelines. Since theseWhile only seven cases were considered definitely doses are of similar size to those used in theprocedure-related, it may be that many of the NCEPOD study of 2002-03, the implication has topost procedure myocardial infarctions, cerebro- be that sedation-related cardiopulmonaryvascular accidents and aspiration pneumonia complications remain more common than iscases were also causally related. Of the 11 generally recognised.pneumonias, 6 cerebro-vascular accidents and 19myocardial infarctions, 24/36, some two-thirds, The East Anglian study showed that the dose ofof these complications occurred within seven either midazolam or pethidine that an individualdays of the procedure. Similarly, in the case of patient is given still appears, in many cases, tothe colonoscopy audit, of the 10 deaths occurring depend as much on the endoscopist performingwithin 30 days of the procedure, some six elderly the procedure as either the age or ASA status ofpatients died from cardio-pulmonary the patient. As illustrated in figures 6 and 7,complications. In several of these, excessive patients over the age of 70 are still regularly beingdoses of sedation may again have had a part to given twice or more of the BSG recommendedplay in the patient’s final demise. dosage of midazolam and pethidine. Furthermore many endoscopists are either unaware of, orRevisiting the two databases has allowed us to choose to ignore, the known synergism betweenexamine the relationship between benzodiazepine benzodiazepines and opioids and use excessivedosage and CNS depression using flumazenil doses of both agents (see figure 8).
12 unnecessarily, by the common practice of notFlumazenil was used in 3.4% of patients in the reducing sedation/analgesia dosage sufficiently toupper GI audit, 3.5% of patients in the allow for their advanced age and co-morbidity. Wecolonoscopy audit and 7% of patients in the strongly recommend that endoscopists adhere tomost recent (and yet largely unpublished) ERCP the BSG 2003 guidelines on sedation dosage andaudit. All these percentages are considerably welcome the NPSA’s recent suggested changes tolower than the reported use of flumazenil in the NHS sedation practice which are, in part, aNCEPOD study where the overall figure of 12% response to the finding of the present study.rose to almost 20% in the case of the ERCPgroup (table 2). These differences might relate, Referencesin part, to the fact that so many of the patients in 1 Report from the Boston Collaborative Drugthe NCEPOD study were on average more frail Surveillance Program, Boston University Medicaland elderly than those in the other audits. Centre. Clinical depression of the central nervous system due to diazepam and chlordiazepoxide inIn the East Anglian study, the overall figure for relation to cigarette smoking and age. N Eng Jflumazenil use was 0.8% of those sedated with Med, 1973. 288: p. 277-280.midazolam. This is almost certainly a grossunderestimate of the true current use of 2 Greenblatt, D.J., Allen, M.D., and Shader, R.I.,flumazenil in UK endoscopy units, since any Toxicity of high-dose flurazepam in the elderly.reversal that is carried out after the patient leaves Clinical Pharmacology and Therapeutics, 1977. 21:the endoscopy unit (or is returned to the ward) p. 355-361.would not normally be recorded on theendoscopy database. The shape of the curve 3 Greenblatt, D.J. and Allen, M.D., Toxicity ofrelating a 5 mg dose of midazolam to age and nitrazepam in the elderly: a report from the Bostonflumazenil use, however, is very similar, if much Collaborative Drug Surveillance Program. Br Jlower, than that generated from properly Clin Pharmac, 1978. 5: p. 407-413.conducted prospective audits with 30-daymorbidity and mortality data (see figures 4 and 5). 4 Harper, K.W., Collier, P.S., et al., Age andMonitoring the use of flumazenil might be one nature of the operation influence theway of prospectively looking at a hospital’s pharmacokinetics of Midazolam. Br J Anaesth,sedation practice, but in the case of an endoscopy 1985. 57: p. 866-871.unit, this would need to include collectinginformation on any doses given after leaving the 5 Castleden, C.M., George, C.F., et al., Increasedunit as well as those given during or immediately sensitivity to nitrazepam in old age. BMJ, 1977. 1:after the procedure. p. 10-12.Conclusions 6 Bell, G., State of the Art Review. Preparation,In patients as ill, frail and complicated as those in Premedication and Surveillance. Endoscopy, 2004.the NCEPOD therapeutic endoscopy study, it is 36: p. 23-31.always very difficult to decide how large a partthe sedation-related cardio-pulmonary 7 Lazzaroni, M. and Biancho Porro, G., State ofcomplications played in any individual patient’s the Art Review. Preparation, Premedication andfinal demise. Based on our detailed study of both Surveillance. Endoscopy, 2005. 37: p. 101-109.the NCEPOD report as well as other relevantdatabases discussed in the present paper, we can 8 Bell, G., Spickett, G.P., et al., Intravenouscertainly conclude that elderly and/or frail Midazolam for upper gastrointestinal endoscopy: apatients’ lives and safety are still being put at risk study of 800 consecutive cases relating dose to age
13and sex of patient. British Journal Clin Pharmac,1987. 23: p. 241-243. 17 Quine, A., Bell, G.D., et al., Prospective audit of upper gastrointestinal endoscopy in two regions9 Smith, M., Bell, G., et al., Small bolus of England: safety, staffing and sedation methods.injections of intravenous Midazolam for upper 1995. 36: p. 462-467.gastrointestinal endoscopy: a study of 788consecutive cases. Br J Clin Pharmac, 1993. 36: 18 Arrowsmith, J., Gerstman, B., et al., Resultsp. 573-578. from the American Society for Gastrointestinal Endoscopy/US Food and Drug Administration10 Bell, G.D., Morden, A., et al., A comparison collaborative study on complication rates and drugof diazepam and Midazolam as endoscopy pre- use during gastrointestinal endoscopy.medication assessing changes in ventilation and Gastrointestinal Endoscopy, 1991. 37: p. 421-7.oxygen desaturation. British Journal ClinPharmac, 1988. 26: p. 595-600. 19 Daneshmend, T.K., Bell, G.D., and Logan, R.F.A., Sedation for upper gastrointestinal11 Bell, G.D., Reeve, P., et al., Intravenous endoscopy: results of a nationwide survey. Gut,Midazolam: a study of the degree of oxygen 1991. 32: p. 12-15.desaturation occurring during uppergastrointestinal endoscopy. British Journal Clin 20 Bowles, C.J.A., Leicester, R., et al., APharmac, 1987. 23: p. 703-708. prospective study of colonoscopy practice in the UK today: are we adequately prepared for national12 Bell, G.D., Bown, N.S., et al., Prevention of colorectal cancer screening tomorrow? Gut, 2004.hypoxaemia during upper gastrointestinal 53(2): p. 277-83.endoscopy using supplemental oxygen via nasalcannulae. Lancet, 1987: p. 1022-1023. 21 Williams, E.J., BSG audit of ERCP. ﾓScoping our Practiceﾔ: the gap between current practice13 Bell, G.D., McCloy, R.F., et al., and recommendations from the NationalRecommendations for Standards of sedation and Confidential Enquiry into Patient Outcome andpatient monitoring during gastrointestinal Death. Gut, 2005. 54 (A11): p. abstract.endoscopy. Gut, 1991. 32: p. 823-827. 22 Scoping our Practice, available at14 Carter, A., Bell, G.D., et al., Speed of reversal www.ncepod.org.uk or as a CD from NCEPOD,of Midazolam -induced respiratory depression by Epworth House, 25 City Road, London EC1YFlumazenil following gastroscopy. Acta 1AA.Anaesthesiol Scand, 1990. 34(Suppl 92): p. 59-64. 23 de la Iglesia, B., Hsu, C., et al., Data mining15 Academy of Medical Royal Colleges Report techniques applied to an Endoscopy data base:of an Intercollegiate Working Party chaired by what additional information might it generate?Royal College of Anaesthetists:- Implementing Gut, 2004 Suppl III. 53 (A51): p. abstract.and ensuring Safe Sedation Practices forhealthcare procedures in adults. November 2001. 24 Debuse, J.C.W., de la Iglesia, B., et al., Buildingwww.aomrc.org.uk the KDD Roadmap: A Methodology for Knowledge Discovery., in Industrial Knowledge16 The British Society of Gastroenterology Management, R. Roy, Editor. 2001, Springer-(BSG) guidelines on sedation, safety and Verlag. p. 179-196.monitoring. November 2003.www.bsg.org.uk/clinical_prac/guidelines/sedation.htm
1425 Lord, D.A., Data Preparation, Coalescing andKnowledge Discovery in Endoscopy Datasets.MSc dissertation School of Computing Sciences,University of East Anglia, 2005.26 Richards, G., Rayward-Smith, V.J., et al., Datamining for Indicators of Early mortality in aDatabase of Clinical Records. Journal ofArtificial Intelligence in Medicine, 2001. 22(3): p.215-231.27 An organisation with a memory. Report of anexpert group on learning from adverse events inthe NHS chaired by the Chief Medical Officer.2000, London: Department of Health.28 National Audit Office report: A safer placefor patients: learning to improve patient safety.www.nao.org.uk29 Ben Shlomo, I., Adb-el-Khalim, H., et al.,Midazolam acts synergistically with Fentanyl forinduction of anaesthesia. British Journal ofAnaesthesia, 1990. 64: p. 45-7.30 Bell, G.D., Antrobus, J.H.L., et al., Bolus orslow titrated injection of Midazolam prior toOGD? Relative effect on oxygen saturation andprophylactic value of supplemental oxygen.Aliment Pharmac Therap, 1990. 4: p. 393-401.31 NPSA Patient Safety Bulletin (to bepublished). firstname.lastname@example.org