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Bridging the analgesic gap
Original Article
Bridging the analgesic gap Alexander Ng, DA(UK), FRCA (1) (2) Fran Hall, RGN, MSc (1) Andrew Atkinson, RGN (1) Kin Leong Kong, MD, FRCA (1) (3) Amanda Hahn, FRCA (1)
Summary In this paper, the concept of the analgesic gap in the postoperative period is defined. An audit was performed to examine the current situation of the adequacy of analgesia following the discontinuation of epidural infusions or intravenous morphine. Out of 89 patients assessed, it was found that 14 (16%), 18 (20%) and eight (9%) patients demonstrated an analgesic gap on Day 0, Day 1 and Day 2 respectively. Of these patients, 9 (64%), 12 (67%) and five (63%) on the respective days had at least one group of analgesics prescribed regularly. Most of these patients prescribed regular analgesia had non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol and moderate analgesics. Oral opioids were not used. It was shown that of the 22 patients with high pain scores on the day of discontinuation of the analgesic pumps, 17 (77'Yo) had their pump withdrawn too early (within 48 hours). In view of our findings, recommendations have been made to improve the provision of postoperative analgesia during this transitional period. Acute Pain 2000; 3 (4): 172-180.
Keywords: analgesic gap; analgesic support; postoperative pain
Introduction In 1991, the Royal College of Surgeons and College of Anaesthetists published a Working Party Report concerning the deficiencies of postoperative pain management.'. In the years following this publication, there have been major improvements in acute pain managernent--' with a significant increase in the number of hospitals with an acute pain service (APS)5. However, the Audit Commission of the United Kingdom has reiterated the current problems with room for further improvernents-. An important issue for which there is little formal data concerns the period of increased pain from the time when full analgesic support, such as an
(1) Dept 4 Anaesthesia, City Hospital NHS Tmst, Dudley Road, Birmin,Rham, UK. (2) Present address: University Dept (ifAnaesthesia and Pain Management, University Hospitals C!f Leicester NHS Trust, Leicester Royal Ir!/irmary, Leicester, UK (3) Address for correspondence: Dr KL Kon.l?, Dept if Anaesthesia, City Hospital, Dudley Road, Birmingham B18 7QH. Tel +44 (0) 121 5543801 ext 4343, Fax +44 (0) 121 507 4349
194
analgesic infusion or a patient controlled analgesic (PCA) device, is withdrawn to the time when analgesia is administered on a less formal basis. This period of increased pain has been called the 'analgesic gap". At City Hospital, an APS has been provided since 1991. Although pain intensity visual analogue scores (VAS) are regularly collected when patients are receiving an analgesic infusion or a PCA, data collection stops when these methods of analgesia are discontinued. Concern was expressed about the possibility of a period of increased pain following the discontinuation of these formal methods of analgesia. Consequently, it was felt necessary to perform an audit. The aims of the audit were to: • Assess the incidence of the patients who experienced a period of increased pain during this transitional period. • Assess the reasons for an analgesic gap such as variations in prescribing practices with regard to simple and moderate analgesics. • Make recommendations on how this analgesic gap could be bridged.
Volume 3 (4) December 2000
Acute Pain
Bridging the analgesic gap Ng et al
Methods
Assessment of analgesic support
Over a four week period, all consecutive patients who were prescribed either an epidural infusion or intravenous opioids (patient controlled opioid analgesia, continuous intravenous opioid infusion) for postoperative pain relief were studied. To facilitate the assessments, the following terms were
The duration of intravenous opioids or epidural infusions was measured. On Days 0, 1 and 2 of the study, we recorded the prescribing habits of the basic analgesic support into three categories: as required (prn), regular, and not prescribed. The drugs used were grouped into a modified World Health Organisation classification: NSAIDs, paracetamol, moderate analgesics and strong analgesics. For further analysis, these patients were subdivided at two levels: one with at least one group of analgesic drugs prescribed regularly, and the other with a combination of as required prescribing and no prescription of analgesics.
defined: • Advanced analgesic support would be the provision of acute pain relief involving epidural analgesia or intravenous opioid analgesics. Patients receiving this support would be the responsibility of the APS. • Basic analgesic support would be the provision of acute pain relief when patients are discontinued from advanced analgesic support. These patients would he supervised by ward doctors. • The analgesic gap would be the interval of increased pain when advanced analgesic support is discontinued and basic analgesic support is commenced. In this study it was decided that the analgesic gap occurred when the pain intensity visual analogue scores increased by 50% or more following the discontinuation of advanced analgesic support.
Data processing and statistical analysis The data were tabulated in Microsoft Access '95. Analysis was performed using Excel '97 and SPSS 7.52. The Wilcoxon test was used for nonparametric paired data to compare pain intensity visual analogue scores on the last day of the advanced analgesic support to the corresponding scores on Day 0, 1 and 2 respectively.
Results Assessment times All patients were assessed on four separate occasions: • Last day of advanced analgesic support. • Day 0: four to eight hours after discontinuation of intravenous opioid or epidural infusion. • Day 1: first day after discontinuation of advanced analgesic support. • Day 2: second day after discontinuation of advanced analgesic support. Assessment of pain intensity and the analgesic gap Assessments were made at the bedside by members of the APS. Pain intensity was assessed on movement in bed or on coughing by the use of a visual analogue device on the four assessment times given above. For the purposes of this study, patients who had pain intensity visual analogue score of less than five on the last day of their advanced analgesic support were deemed to have adequate analgesic control. The analgesic gap was considered to be present if o res increased by 50% or more during the t h ese sc period of basic analgesic support.
Acute Pain
We studied a total of 89 postoperative patients receiving intravenous opioids or epidural infusions. There were 25 males with a median age of 54 (min-max: 1(}-79) and 64 females with a median age of 50 (min-max: 22-94). The number of patients in each surgical speciality has been summarised in Table 1. Advanced analgesic support Most of the 89 patients were given intravenous morphine via a PCA device, as shown in Table 2. There were 22 (25%) patients who had high pain intensity scores (VAS ~5) at the time of Surgical speciality
Number of patients
Gynaecology General abdominal Orthopaedics General non-abdominal Vascular Urology Maxillofacial
2H 26 17 9 4 3 2
Table 1: Number (!(p
Volume 3 (4) December 2000
(0
surgica!
195
Bridging the analgesic gap Ng et al
Type PCA morphine with droperidol PCA morphine without droperidol
Morphine infusion Epidural with an opioid Epidural without an opioid
Number of patients 61 20 2 4 2
Percentage of patients,
69 22 2 4
2
Table 2: Advanced analoesic support provided Number of patients
Duration of advanced analgesic support
Number of patients
<5
67
:5:48 >48
40 27
~5
22
~48
17 5
Pain score on last day of advanced analgesic support (VAS)
>48
Table J:Nwnbcr of patients with h(~h and lowpain scores on discontinuation of advanced analyesic support Day
Lastday of advanced analgesic support 1 2 3
Median pain VAS (Interquartile range)
p
3.3 (2.2-4.8) 3.1 (2.0-5.0) 2.8 (1.5-5.0) 2.0 (0.9-3.3)
0.03 0.06 <0.01
Table 4: Visual tII/(/J(~~lIe pain intensity scores at thejour timeperiods. Comparisons cf Day 0, Day 1 ami Day 2 with the last day (![ advanced analyesic support were made, and S(I!II!{rcat/(e is.I!il'ol [,y I'
discontinuation of advanced analgesic support (Table
1). Of these 22 patients, 17 (7TYo) were taken off their intravenous opioids or epidural infusions after hours.
~4H
Basic analgesic support The prescribing frequency of NSAI])s, paracetamol, moderate analgesics and strong analgesics is summarised in Figures 1, 2, 1 and 4 respectively. Very few patients were prescribed strong opioid analgesics as part of their basic analgesic support. A third of patients were prescribed NSAIl)s and half our patients were prescribed moderate analgesics on an as required basis. NSAI])s and moderate analgesics were prescribed regularly in a quarter of all patients.
196
Pain intensity and the analgesic gap On the last day of the intravenous opioid or epidural infusion, the median visual analogue pain intensity scores of the patients was 3.3. These scores were lower on subsequent assessments, decreasing significantly (p< 0.0(1) by Day 2 (Table 4).
Discussion The existence of the analgesic gap The definition of what constitutes a significant increase in pain in the transitional period following the discontinuation of advanced analgesic support is open to debate. There are two important considerations. First, in order to assess if patients experienced an increase in pain in the transitional period. the
Volume 3 (4) December 2000
Acute Pain
Brid ging the anal gesic ga p
80
80
70
70
1Il
cOO
1Il
. Oay O II Oay 1 o Oay 2
.s
~50
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60
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~ 30
.0
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20 10
10
0
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reg
missing
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F(C Jlrt' 1: Prescription C!f non-steroidal al/t;;,if/allllllatory dmgs
reg
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F(I!. /Irc 2: Prescription <1 pnracctamo]
90
80 70
80
60
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1Il
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0 40
iii 30
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20
20
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Fi.CJlrr 3 : Prescription C!f moderate analocsics (prcdllll/;/Ia/ltly r(ldydral//lll)
patients had to haw sufficient analgesia at the end of the ir adva nced an alges ic su p po r t. A pain visua l . naloguc sco re of less th an five was co nside red to be the cut- o ff point. above w hic h th e probl em was not related t o th e ana lges ic ga p. bu t to t he p o or provi sio n of th e adva nce d analgesic su ppo rt. T he o ther issue co nce rned how mu ch sho uld the pain sco re increase in th e transitio nal peri od before it was co nside red to be an im po rtant change. In th is aud it. a 50'% increase in pain visual analogue sco re . 'Irbitn. rily co nsidered to be a significant increase. \vas. This figu re was em ployed on the rationa le that the efficac y of analgesic drugs has been ba:ed o n a SO'y., redu ct io n in pain". O ther meth o ds to add ress th is change in pain co uld have used a catego rical scale of no change. a little worse. a lot worse. a little be tter and a lot better". Th e simila rity of both meth od s is tha t t hey ta ke in to ac co u n t pat ie n ts' base li ne ' o n of th eir pain .Th e p robl em w it h the pe rce p tl . ' . . me thod using the 50% mcrcase 111 pall1 IS that at low
A c ute P ain
. Oay O Oay1 o Day2
50
ilE 40
:i.
.0 :J
o
prn
Fi.I!. /Irr 4: Prescription
reg
missing
<1 stnlll.l! Ill/a{l!es;cs
baselin e pain scores . a 50% increase in pain may not be perceived as a probl em by patients. and at high er baseline pain sco res. a 50% increase in pain may mi ss problem s perceived by patients. I n the former case. th er efore. th ere wi ll be an ove r- diagnosis of th e analgesic gap and in th e latte r case th ere wi ll be an under det ecti on . T he use of 50% was o ne m eth od to id enti fy the prop orti on o f pati ents wi th th e ana lgesic gap, From th e acute pain wa rd rounds. it was clear th at som e of the pati ents in th e audit were troubled by increased pain during the transiti on al period and th e magni tude o f 50% was o ne numeri cal m eth od to q ua ntify thi s change . T he im po rta nce of thi s aud it lies n ot so mu ch in try ing to d e fin e th e p recise in ciden ce o f th e ana lgesic gap. but to iden tify its existe nce and to evalua te how the analgesic gap can be br idge d. Prescr ibing pr actice of basic ana lgesic su p port O ur of the patients w ho dcm on srratcd an ana lgesic
Vo lu me 3 (4) Dece mbe r 2000
197
Bridging the analgesic gap Ng et al
Day number
Pain score on last day of advanced analgesic support (VAS)
Number of patients
Number Increase in pain score on day of basic of patients analgesic support compared with pain on last day of advanced analgesic support
()
<5
67
<50%
47
~50%
14
Unavailable
6
<50%
21
~50%
0
~5
22
Unavailable
<5
~5
67
22
<50%
49
~50%
18
<50%
21
~50%
2
<5
~5
67
22
<50%
20
~50%
8
Unavailable
6
<50%
20
~50'X,
1
Unavailable
Number Frequency of basic analgesic of patients support in ~1 group of drugs
Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular
26 21 5 9 5 1 12 9 0 0 0 1
Not regular Regular Not regular Regular Not regular Regular Not regular Regular
23 26 6 12 10 11 0 1
Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular
24 29 3 5 6 0 11 9 0 1 1 0
Table 5: Tahlc relatill,I( the patients with analgesic gap to thefreqHftlcy
gap, it was found that nine (64'YcI), 12 (67%) and 5 (63%) patients on Day 0, Day 1 and Day 2 respectively, had at least one group of analgesics prescribed regularly (Table 5). These analgesics consisted of NSAIDs, paracetamol and moderate analgesics. Only three of these patients had two groups of simple and moderate analgesics prescribed regularly. Three groups of analgesics and strong opioids were not prescribed regularly. The implications here are that regular prescribing of more
198
than one group of analgesics would have been desirable. For the patients whose pain is not adequately managed on regular simple and moderate analgesics, it would be necessary to introduce an additional method. Strong oral opioids have been suggested. However, for this group of drugs to be considered, the issues of the return of gastric motility and nausea would need to be addressed. Oxycodone has been put forward 7 as a possible method to bridge the analgesic gap. There is evidence that this drug is
Volume 3 (4) December 2000
Acute Pain
Bridging the analgesic gap Ng et al
effective for the management of postoperative pain following knee surgery!", other orthopaedic procedures, abdominal and thoracic surgery". Advanced analgesic support It was of concern that out of the 57 patients who had their advanced analgesic support discontinued within 48 hours postoperatively, 17 patients (30010) had high 0/AS ~5) pain scores (Table 3). In comparison, out of the remaining 32 patients who had their advanced analgesic support for more than 48 hours,S (16%) patients had high (VAS ~5) pain scores. In this group of five patients, no patient had their advanced analgesic support for more than 72 hours. Clearly, these patients would have benefited from further assessment and consideration of an extension of the duration of advanced analgesic support. Recommendations The key stakeholders in the management of the analgesic gap are the patient, the APS, the surgeons, the patient's employers, the researcher and ultimately the health service. The aims of all concerned are to ensure that the patient receives sufficient pain relief. Good analgesia during this transitional period may facilitate recovery, hospital discharge and return to work. The evidence in this area of acute pain management is sparse and the researcher needs to provide the clinicians with more evidence and further methods of analgesia. This audit has identified the analgesic gap in the provision of postoperative analgesia and the factors that contribute to this problem have been highlighted. From the evidence presented, it is possible to make the following recommendations: • Advanced analgesic support should not be discontinued when pain intensity scores remain high and when basic analgesic support will be insufficient to keep postoperative pain to a minimum. • Basic analgesic support should be prescribed regularly. This practice would ensure that, on each drug round, the requirement of analgesia is informally assessed. Patients can refuse the
Acute Pain
analgesia if they are not in pain. As required prescriptions lead to inconsistent pain relief. In addition, a combination of drugs may be required such as paracetamol and a NSAID. • The use of oral opioids 24 hours after the return of gastric motility may be required to bridge the analgesic gap. In providing this intermediate form of support, which is currently unfamiliar to the clinicians in the hospital, it would be advisable to monitor its safety and efficacy. References 1. Royal College of Surgeons of England and College of Anaesthetists. Report of the Working Party on Pain after Surgery. London: Royal College of Surgeons, 1990. 2. Cartwright PD, Helfinger RG, Howell]], Siepmann KK. Introducing an acute pain service. Anaesthesia 1991; 46: 188-191. 3. Gould TH, Crosby DL, Hanner M, Lloyd SM, et al. Policy for controlling pain after surgery: effect of sequential changes in management. BM] 1992; 305: 1187-1193. 4. Mcquay H], Moore A, ]ustins D. Treating acute pain in hospital. BM] 1997; 314: 1531-1535. 5. Windsor AM, Glynn C], Mason DG. National provision of acute pain services. Anaesthesia 1996; 51: 228-231. 6. Audit Commission. Anaesthesia Under Examination. London: Belmont Press, 1997. 7. Smith G, Power I. Audit and bridging the analgesic gap. Anaesthesia 1998; 53:521-522. 8. Mcquay H], Moore A. An Evidence Based Resource for Pain Reliif Oxford: Oxford University Press, 1998. 9. Kelly AM. Does the clinically significant difference in visual analogue pain scores vary with gender, age or cause of pain? Acad Emerg Med 1998; 5(11):10861090. 10. Reuben SS, Connelly NR, Maciolek H. Postoperative analgesia with controlled-release oxycodone for outpatient anterior cruciate ligament surgery. Anesth Analg 1999; 88(6): 1286-1291. 11. Ginsberg B, Sinatra R, Crews], Hord A, Adler L, Lockhart E. Conversion from iv PCA morphine to oral controlled release oxycodone for postoperative pain management. Anesth Ana{~ 1998; 86 (2S): 271S.
Volume 3 (4) December 2000
199
Bridging the analgesic gap Alexander Ng, DA(UK), FRCA (1) (2) Fran Hall, RGN, MSc (1) Andrew Atkinson, RGN (1) Kin Leong Kong, MD, FRCA (1) (3) Amanda Hahn, FRCA (1)
Summary In this paper, the concept of the analgesic gap in the postoperative period is defined. An audit was performed to examine the current situation of the adequacy of analgesia following the discontinuation of epidural infusions or intravenous morphine. Out of 89 patients assessed, it was found that 14 (16%), 18 (20%) and eight (9%) patients demonstrated an analgesic gap on Day 0, Day 1 and Day 2 respectively. Of these patients, 9 (64%), 12 (67%) and five (63%) on the respective days had at least one group of analgesics prescribed regularly. Most of these patients prescribed regular analgesia had non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol and moderate analgesics. Oral opioids were not used. It was shown that of the 22 patients with high pain scores on the day of discontinuation of the analgesic pumps, 17 (77'Yo) had their pump withdrawn too early (within 48 hours). In view of our findings, recommendations have been made to improve the provision of postoperative analgesia during this transitional period. Acute Pain 2000; 3 (4): 172-180.
Keywords: analgesic gap; analgesic support; postoperative pain
Introduction In 1991, the Royal College of Surgeons and College of Anaesthetists published a Working Party Report concerning the deficiencies of postoperative pain management.'. In the years following this publication, there have been major improvements in acute pain managernent--' with a significant increase in the number of hospitals with an acute pain service (APS)5. However, the Audit Commission of the United Kingdom has reiterated the current problems with room for further improvernents-. An important issue for which there is little formal data concerns the period of increased pain from the time when full analgesic support, such as an
(1) Dept 4 Anaesthesia, City Hospital NHS Tmst, Dudley Road, Birmin,Rham, UK. (2) Present address: University Dept (ifAnaesthesia and Pain Management, University Hospitals C!f Leicester NHS Trust, Leicester Royal Ir!/irmary, Leicester, UK (3) Address for correspondence: Dr KL Kon.l?, Dept if Anaesthesia, City Hospital, Dudley Road, Birmingham B18 7QH. Tel +44 (0) 121 5543801 ext 4343, Fax +44 (0) 121 507 4349
194
analgesic infusion or a patient controlled analgesic (PCA) device, is withdrawn to the time when analgesia is administered on a less formal basis. This period of increased pain has been called the 'analgesic gap". At City Hospital, an APS has been provided since 1991. Although pain intensity visual analogue scores (VAS) are regularly collected when patients are receiving an analgesic infusion or a PCA, data collection stops when these methods of analgesia are discontinued. Concern was expressed about the possibility of a period of increased pain following the discontinuation of these formal methods of analgesia. Consequently, it was felt necessary to perform an audit. The aims of the audit were to: • Assess the incidence of the patients who experienced a period of increased pain during this transitional period. • Assess the reasons for an analgesic gap such as variations in prescribing practices with regard to simple and moderate analgesics. • Make recommendations on how this analgesic gap could be bridged.
Volume 3 (4) December 2000
Acute Pain
Bridging the analgesic gap Ng et al
Methods
Assessment of analgesic support
Over a four week period, all consecutive patients who were prescribed either an epidural infusion or intravenous opioids (patient controlled opioid analgesia, continuous intravenous opioid infusion) for postoperative pain relief were studied. To facilitate the assessments, the following terms were
The duration of intravenous opioids or epidural infusions was measured. On Days 0, 1 and 2 of the study, we recorded the prescribing habits of the basic analgesic support into three categories: as required (prn), regular, and not prescribed. The drugs used were grouped into a modified World Health Organisation classification: NSAIDs, paracetamol, moderate analgesics and strong analgesics. For further analysis, these patients were subdivided at two levels: one with at least one group of analgesic drugs prescribed regularly, and the other with a combination of as required prescribing and no prescription of analgesics.
defined: • Advanced analgesic support would be the provision of acute pain relief involving epidural analgesia or intravenous opioid analgesics. Patients receiving this support would be the responsibility of the APS. • Basic analgesic support would be the provision of acute pain relief when patients are discontinued from advanced analgesic support. These patients would he supervised by ward doctors. • The analgesic gap would be the interval of increased pain when advanced analgesic support is discontinued and basic analgesic support is commenced. In this study it was decided that the analgesic gap occurred when the pain intensity visual analogue scores increased by 50% or more following the discontinuation of advanced analgesic support.
Data processing and statistical analysis The data were tabulated in Microsoft Access '95. Analysis was performed using Excel '97 and SPSS 7.52. The Wilcoxon test was used for nonparametric paired data to compare pain intensity visual analogue scores on the last day of the advanced analgesic support to the corresponding scores on Day 0, 1 and 2 respectively.
Results Assessment times All patients were assessed on four separate occasions: • Last day of advanced analgesic support. • Day 0: four to eight hours after discontinuation of intravenous opioid or epidural infusion. • Day 1: first day after discontinuation of advanced analgesic support. • Day 2: second day after discontinuation of advanced analgesic support. Assessment of pain intensity and the analgesic gap Assessments were made at the bedside by members of the APS. Pain intensity was assessed on movement in bed or on coughing by the use of a visual analogue device on the four assessment times given above. For the purposes of this study, patients who had pain intensity visual analogue score of less than five on the last day of their advanced analgesic support were deemed to have adequate analgesic control. The analgesic gap was considered to be present if o res increased by 50% or more during the t h ese sc period of basic analgesic support.
Acute Pain
We studied a total of 89 postoperative patients receiving intravenous opioids or epidural infusions. There were 25 males with a median age of 54 (min-max: 1(}-79) and 64 females with a median age of 50 (min-max: 22-94). The number of patients in each surgical speciality has been summarised in Table 1. Advanced analgesic support Most of the 89 patients were given intravenous morphine via a PCA device, as shown in Table 2. There were 22 (25%) patients who had high pain intensity scores (VAS ~5) at the time of Surgical speciality
Number of patients
Gynaecology General abdominal Orthopaedics General non-abdominal Vascular Urology Maxillofacial
2H 26 17 9 4 3 2
Table 1: Number (!(p
Volume 3 (4) December 2000
(0
surgica!
195
Bridging the analgesic gap Ng et al
Type PCA morphine with droperidol PCA morphine without droperidol
Morphine infusion Epidural with an opioid Epidural without an opioid
Number of patients 61 20 2 4 2
Percentage of patients,
69 22 2 4
2
Table 2: Advanced analoesic support provided Number of patients
Duration of advanced analgesic support
Number of patients
<5
67
:5:48 >48
40 27
~5
22
~48
17 5
Pain score on last day of advanced analgesic support (VAS)
>48
Table J:Nwnbcr of patients with h(~h and lowpain scores on discontinuation of advanced analyesic support Day
Lastday of advanced analgesic support 1 2 3
Median pain VAS (Interquartile range)
p
3.3 (2.2-4.8) 3.1 (2.0-5.0) 2.8 (1.5-5.0) 2.0 (0.9-3.3)
0.03 0.06 <0.01
Table 4: Visual tII/(/J(~~lIe pain intensity scores at thejour timeperiods. Comparisons cf Day 0, Day 1 ami Day 2 with the last day (![ advanced analyesic support were made, and S(I!II!{rcat/(e is.I!il'ol [,y I'
discontinuation of advanced analgesic support (Table
1). Of these 22 patients, 17 (7TYo) were taken off their intravenous opioids or epidural infusions after hours.
~4H
Basic analgesic support The prescribing frequency of NSAI])s, paracetamol, moderate analgesics and strong analgesics is summarised in Figures 1, 2, 1 and 4 respectively. Very few patients were prescribed strong opioid analgesics as part of their basic analgesic support. A third of patients were prescribed NSAIl)s and half our patients were prescribed moderate analgesics on an as required basis. NSAI])s and moderate analgesics were prescribed regularly in a quarter of all patients.
196
Pain intensity and the analgesic gap On the last day of the intravenous opioid or epidural infusion, the median visual analogue pain intensity scores of the patients was 3.3. These scores were lower on subsequent assessments, decreasing significantly (p< 0.0(1) by Day 2 (Table 4).
Discussion The existence of the analgesic gap The definition of what constitutes a significant increase in pain in the transitional period following the discontinuation of advanced analgesic support is open to debate. There are two important considerations. First, in order to assess if patients experienced an increase in pain in the transitional period. the
Volume 3 (4) December 2000
Acute Pain
Brid ging the anal gesic ga p
80
80
70
70
1Il
cOO
1Il
. Oay O II Oay 1 o Oay 2
.s
~50
~(J) 40
c .!!!
60
Cii 50 Co 0 40
. Oay O . Oay 1 o Oay 2
Qj E 30
~ 30
.0
z20
z
:J
N.l! et al
:J
20 10
10
0
0 pm
reg
missing
prn
F(C Jlrt' 1: Prescription C!f non-steroidal al/t;;,if/allllllatory dmgs
reg
missing
F(I!. /Irc 2: Prescription <1 pnracctamo]
90
80 70
80
60
c 70 .!!!
1Il
1Il
C Q) .~
Cii 60 Co
50
. Oay O . Oay 1 o Oay 2
Co
0 40
iii 30
E
z
30
20
20
10
10 0
0 prn
reg
missing
Fi.CJlrr 3 : Prescription C!f moderate analocsics (prcdllll/;/Ia/ltly r(ldydral//lll)
patients had to haw sufficient analgesia at the end of the ir adva nced an alges ic su p po r t. A pain visua l . naloguc sco re of less th an five was co nside red to be the cut- o ff point. above w hic h th e probl em was not related t o th e ana lges ic ga p. bu t to t he p o or provi sio n of th e adva nce d analgesic su ppo rt. T he o ther issue co nce rned how mu ch sho uld the pain sco re increase in th e transitio nal peri od before it was co nside red to be an im po rtant change. In th is aud it. a 50'% increase in pain visual analogue sco re . 'Irbitn. rily co nsidered to be a significant increase. \vas. This figu re was em ployed on the rationa le that the efficac y of analgesic drugs has been ba:ed o n a SO'y., redu ct io n in pain". O ther meth o ds to add ress th is change in pain co uld have used a catego rical scale of no change. a little worse. a lot worse. a little be tter and a lot better". Th e simila rity of both meth od s is tha t t hey ta ke in to ac co u n t pat ie n ts' base li ne ' o n of th eir pain .Th e p robl em w it h the pe rce p tl . ' . . me thod using the 50% mcrcase 111 pall1 IS that at low
A c ute P ain
. Oay O Oay1 o Day2
50
ilE 40
:i.
.0 :J
o
prn
Fi.I!. /Irr 4: Prescription
reg
missing
<1 stnlll.l! Ill/a{l!es;cs
baselin e pain scores . a 50% increase in pain may not be perceived as a probl em by patients. and at high er baseline pain sco res. a 50% increase in pain may mi ss problem s perceived by patients. I n the former case. th er efore. th ere wi ll be an ove r- diagnosis of th e analgesic gap and in th e latte r case th ere wi ll be an under det ecti on . T he use of 50% was o ne m eth od to id enti fy the prop orti on o f pati ents wi th th e ana lgesic gap, From th e acute pain wa rd rounds. it was clear th at som e of the pati ents in th e audit were troubled by increased pain during the transiti on al period and th e magni tude o f 50% was o ne numeri cal m eth od to q ua ntify thi s change . T he im po rta nce of thi s aud it lies n ot so mu ch in try ing to d e fin e th e p recise in ciden ce o f th e ana lgesic gap. but to iden tify its existe nce and to evalua te how the analgesic gap can be br idge d. Prescr ibing pr actice of basic ana lgesic su p port O ur of the patients w ho dcm on srratcd an ana lgesic
Vo lu me 3 (4) Dece mbe r 2000
197
Bridging the analgesic gap Ng et al
Day number
Pain score on last day of advanced analgesic support (VAS)
Number of patients
Number Increase in pain score on day of basic of patients analgesic support compared with pain on last day of advanced analgesic support
()
<5
67
<50%
47
~50%
14
Unavailable
6
<50%
21
~50%
0
~5
22
Unavailable
<5
~5
67
22
<50%
49
~50%
18
<50%
21
~50%
2
<5
~5
67
22
<50%
20
~50%
8
Unavailable
6
<50%
20
~50'X,
1
Unavailable
Number Frequency of basic analgesic of patients support in ~1 group of drugs
Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular
26 21 5 9 5 1 12 9 0 0 0 1
Not regular Regular Not regular Regular Not regular Regular Not regular Regular
23 26 6 12 10 11 0 1
Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular Not regular Regular
24 29 3 5 6 0 11 9 0 1 1 0
Table 5: Tahlc relatill,I( the patients with analgesic gap to thefreqHftlcy
gap, it was found that nine (64'YcI), 12 (67%) and 5 (63%) patients on Day 0, Day 1 and Day 2 respectively, had at least one group of analgesics prescribed regularly (Table 5). These analgesics consisted of NSAIDs, paracetamol and moderate analgesics. Only three of these patients had two groups of simple and moderate analgesics prescribed regularly. Three groups of analgesics and strong opioids were not prescribed regularly. The implications here are that regular prescribing of more
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than one group of analgesics would have been desirable. For the patients whose pain is not adequately managed on regular simple and moderate analgesics, it would be necessary to introduce an additional method. Strong oral opioids have been suggested. However, for this group of drugs to be considered, the issues of the return of gastric motility and nausea would need to be addressed. Oxycodone has been put forward 7 as a possible method to bridge the analgesic gap. There is evidence that this drug is
Volume 3 (4) December 2000
Acute Pain
Bridging the analgesic gap Ng et al
effective for the management of postoperative pain following knee surgery!", other orthopaedic procedures, abdominal and thoracic surgery". Advanced analgesic support It was of concern that out of the 57 patients who had their advanced analgesic support discontinued within 48 hours postoperatively, 17 patients (30010) had high 0/AS ~5) pain scores (Table 3). In comparison, out of the remaining 32 patients who had their advanced analgesic support for more than 48 hours,S (16%) patients had high (VAS ~5) pain scores. In this group of five patients, no patient had their advanced analgesic support for more than 72 hours. Clearly, these patients would have benefited from further assessment and consideration of an extension of the duration of advanced analgesic support. Recommendations The key stakeholders in the management of the analgesic gap are the patient, the APS, the surgeons, the patient's employers, the researcher and ultimately the health service. The aims of all concerned are to ensure that the patient receives sufficient pain relief. Good analgesia during this transitional period may facilitate recovery, hospital discharge and return to work. The evidence in this area of acute pain management is sparse and the researcher needs to provide the clinicians with more evidence and further methods of analgesia. This audit has identified the analgesic gap in the provision of postoperative analgesia and the factors that contribute to this problem have been highlighted. From the evidence presented, it is possible to make the following recommendations: • Advanced analgesic support should not be discontinued when pain intensity scores remain high and when basic analgesic support will be insufficient to keep postoperative pain to a minimum. • Basic analgesic support should be prescribed regularly. This practice would ensure that, on each drug round, the requirement of analgesia is informally assessed. Patients can refuse the
Acute Pain
analgesia if they are not in pain. As required prescriptions lead to inconsistent pain relief. In addition, a combination of drugs may be required such as paracetamol and a NSAID. • The use of oral opioids 24 hours after the return of gastric motility may be required to bridge the analgesic gap. In providing this intermediate form of support, which is currently unfamiliar to the clinicians in the hospital, it would be advisable to monitor its safety and efficacy. References 1. Royal College of Surgeons of England and College of Anaesthetists. Report of the Working Party on Pain after Surgery. London: Royal College of Surgeons, 1990. 2. Cartwright PD, Helfinger RG, Howell]], Siepmann KK. Introducing an acute pain service. Anaesthesia 1991; 46: 188-191. 3. Gould TH, Crosby DL, Hanner M, Lloyd SM, et al. Policy for controlling pain after surgery: effect of sequential changes in management. BM] 1992; 305: 1187-1193. 4. Mcquay H], Moore A, ]ustins D. Treating acute pain in hospital. BM] 1997; 314: 1531-1535. 5. Windsor AM, Glynn C], Mason DG. National provision of acute pain services. Anaesthesia 1996; 51: 228-231. 6. Audit Commission. Anaesthesia Under Examination. London: Belmont Press, 1997. 7. Smith G, Power I. Audit and bridging the analgesic gap. Anaesthesia 1998; 53:521-522. 8. Mcquay H], Moore A. An Evidence Based Resource for Pain Reliif Oxford: Oxford University Press, 1998. 9. Kelly AM. Does the clinically significant difference in visual analogue pain scores vary with gender, age or cause of pain? Acad Emerg Med 1998; 5(11):10861090. 10. Reuben SS, Connelly NR, Maciolek H. Postoperative analgesia with controlled-release oxycodone for outpatient anterior cruciate ligament surgery. Anesth Analg 1999; 88(6): 1286-1291. 11. Ginsberg B, Sinatra R, Crews], Hord A, Adler L, Lockhart E. Conversion from iv PCA morphine to oral controlled release oxycodone for postoperative pain management. Anesth Ana{~ 1998; 86 (2S): 271S.
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