105
The Effect, on Injection Pain, of Adding Lignocaine to Propofol G. N. NEWCOMBE* Lyell McEwin Health Service, Elizabeth Vale, South Australia Key Words: ANAESTHESIA, ANESTHESIA, INTRAVENOUS: outpatient, propofol, lignocaine
Propofol has proven to be a useful anaesthetic induction agent, especially for day case surgery. I It often, however, causes pain on injection. Various strategies have been tried to minimise or prevent this pain. 2 The most successful of these appear to be injection in the antecubital fossa 2 and the addition of lignocaine. 2•3 The latter study,3 however, has been criticised for its use of variable premedication, variable preinduction opioid and lack of controls. 2 This study was designed as a double blind controlled trial to assess the effect of the ad~iition oflignocaine to propofol on injection pam. MATERIALS AND METHODS The study was approved by the hospital ethics committee, and informed consent was obtained from all subjects. The subjects were 100 ASA 1 patients presenting for day case surgery. Those who required premedication were to be excluded. Using a table of random numbers and numbered envelopes, patients were assigned to receive either propofol and 1.0 ml of normal saline or propofol and 1.0 ml of 1% lignocaine plain. The solution was made up by an anaesthetist or registered nurse who was not involved with the case and had to be used within ten minutes of addition. The nature of the additive to the propofol was thus unknown to both patient and anaesthetist. *F.F.A.R.A.C.S .• Staff Specialist. Address for Reprints: Dr. G. N. Newcombe. cl· LyeU McEwin Health Service. Haydown Road. Elizabeth Vale. South Australia 5112. Accepted for publication September 18. 1989
Anaesthesia and intensive Care. Vol. 18. No. I. February'. 1990
No attempt to actively mix the liquids was made. The syringe was not shaken or inverted, but rather allowed to just sit on the anaesthetic workbench. A 23-gauge butterfly needle was inserted into a vein on the dorsum of the hand. Propofol was the first drug given, and speed of injection was standardised, the first 10 ml being given over 20-30 seconds. If the patients had not complained of pain after the initial ten millilitres, they were asked 'Is that painful?' Pain on injection was thus rated as: no pain; pain on questioning after 10 ml; or spontaneous complaint of pain. Postoperatively the subjects were visited by a third anaesthetist and asked to score the injection pain on a 10 cm visual analogue scale. They were also asked if they would be prepared to have the same induction drug agam. RESULTS Seven patients were excluded. The reasons are given in Table 1. Forty-seven patients received lignocaine and forty-six received saline. There were forty-one females in both groups. This preponderence of females is a reflection of the large amount of gynaecological day case surgery done at this hospital. The average age of patients in the TABLE
1
Reasons for patient exclusion Refusal to participate Language difficulties No venous access Mixture left too long Incomplete documentation
2 1
2 1 1
G. N. NEWCOMBE
106 TABLE 2 Response to propojo/ injection
no pain lignocaine 24 saline 6 X2 = 17.10 P=0.00019
pain on questioning 15
spontaneous complaint of pain 8
19
21
saline group was 29 years (range 17-57) and the lignocaine group 28 (range 16-56). The incidence of pain on injection is shown in Table 2. The addition of lignocaine greatly reduced patient discomfort. This was highly significant (Chi 2 = 17.1, 2DF, P=0.00019). Eleven patients (23%) in the lignocaine group had scores of 0, compared with three (65%) in the saline group; The median score for lignocaine was 0.9 and for saline 4.25. The results are presented in Figure 1.
30
~
•
Lignocaine
~
Saline
20
cQ)
~
-... Q.
o
Q)
.c
E
::J
Z
10
o
o to 2
4.1 to 6 Gr. than 6 2.1 to 4 I.-Visual analogue pain scores plotted against number of patients receiving propofol with lignocaine or with saline. FIGURE
Statistical testing of ranking of pain scores also showed a highly significant difference between the two groups (Mann Whitney test statistics 510.5, two-tailed normal, P< 0.00001). When questioned postoperatively two patients in the lignocaine group (4.3%) and thirteen patients in the saline group (29%) wished not to have the same again (Chi 2 = 9.6, 1DF, P < 0.002). DISCUSSION
Propofol is one of the preferred induction agents for day case surgery. Injection pain is a problem, and has been the subject of several reports. Lignocaine pretreatment has not been effective in these studies, which include the Australian multicentre evaluation of propofol. 2-5 One of these studies did report a drop in incidence of pain from 37.5% to 17.5% but this was not statistically significant. 5 The addition of lignocaine to propofol has previously been demonstrated to be effective in reducing the incidence of discomfort. 2.3 The first of these studies 2 makes no mention of blinding the observer. The second 3 was a pilot study and has correctly been criticised 2 for non-randomisation, variable premedication and variable pre-administration opioid. There is no discussion in other reports of how the lignocaine was 'mixed' or 'added'. In this study no active effort was made to mix the additives with the propofol, i.e. the syringe was not shaken, stirred or inverted. This was done to confirm the clinical impression of one of the members of the department that this was an effective method . Our study confirms, in a blinded, randomised and controlled fashion, that the addition of lignocaine to propofol significantly reduces the incidence and severity of pain on injection when propofol is given through a butterfly needle in the dorsum of the hand. No attempt has been made to elucidate the reason(s} for this. A simplistic explanation is that lignocaine anaesthetises the vein wall. Another is that it stabilises the kinin cascade. 2 Even with lignocaine some patients will experience discomfort, one patient in the lignocaine group scoring 10, 'the worst pain you can imagine'. Injection into an anteAnaesthesia and In/ensi.-e Care. Vol. 18. No. I. Februar),. 1990
LIGNOCAINE AND PROPOFOL cubital fossa vein is likely to further reduce the incidence of discomfort. 2,5 SUMMARY This double-blind controlled trial has shown that the addition of lignocaine to propofol modifies the pain on injection of propofol given through a butterfly needle in a vein on the dorsum of the hand. The addition of lignocaine resulted in fewer spontaneous complaints of pain, more patients with no pain, lower pain scores and greater patient acceptance. ACKNOWLEDGEMENTS I would like to thank Richard McDonoughGlenn, the Lyell McEwin Health Service Librarian, and Ms. Coral Arnold for their help with the preparation of this project.
I.
107
REFERENCES Heath PJ, Kennedy DJ, Ogg TW, Dunling C, Gilks WR. Which intravenous induction agent for day surgery? A comparison of propofol, thiopentone, methohexitone and etomidate, Anaesthesia 1988; 43:365-368,
2, Scott RPF, Saunders DA, Norman J, Propofol: Clinical strategies for preventing the pain of injection, Anaesthesia 1988; 43:492-494, 3, Brooker J, Hull CJ, Strattford M, Effect on lignocaine on pain caused by propofol injection: letter Anaesthesia 1985; 40:91-92, 4, Russell WJ, A multicentre evaluation ofpropofol in Australia. Abstracts Australian Society of Anaesthetists AGM 1988. Anaesth Intens Care 1989; 17:97- 106.
5, McCulloch MJ, Lees NW, Assessment and modification of pain on induction with propofol (diprivan), Anaesthesia 1985; 40: 1117-1120.
Does the Radial Arterial Line Degrade the Performance of a Pulse Oximeter? R. W. MORRIS,* M. NAIRNt M. BEAUDOINt
Department of Anaesthesia and Intensive Care, The Prince Henry and Prince of Wales Hospitals, Sydney, Australia SUMMARY
The presence of radial arterial lines may diminish distal digital perfusian, Using a pair of pulse oximeters on the index fingers of cannulated and noncannulated arms the saturation and oximeter pulse strength were assessed. Three hundred paired measurements in fifty consecutive Intensive Care patients were undertaken more than two 'hours after cannula insertion. The pulse strength was 19,7 (SD 6,1) and 19.7 (SD 5.7) on the cannulated and noncannulated sides while the saturation was 97.3 (SD 2.3) and 97.1 (SD 2.4) respectively. These differences are not clinically important and the study demonstrates that reliable pulse oximetry measurements may be made distal ta a radial artery cannula, It is recommended that in each individual the placement of the sensor be such as to ensure the best signal and the most stable saturation readings. Key Words: EQUIPMENT: pulse oximetry, limitations, arterial cannulae, complications; MONITORING: oximetry, arterial blood pressure, measurement
*F.F.A.R.A.C.S., Staff Specialist. tAnaesthetic Technician. tF.F.A.R.A.C.S., Staff Specialist. Address for Reprints: Or. R. W. Morris, Department of Anaesthesia, St. George Hospital, Belgrave Street, Kogarah N.S. W., Australia Accepted for publication August 30, 1989 Anaesthesia and Intensive Care. Vol. 18, No. 1. February, 1990
The pulse oximeter is rapidly becoming accepted as a mandatory monitor during anaesthesia. Various authors have demonstrated that oximetry reveals operative hypoxaemial,2 and that pulse oximetry
The Effect, on Injection Pain, of Adding Lignocaine to Propofol G. N. NEWCOMBE* Lyell McEwin Health Service, Elizabeth Vale, South Australia Key Words: ANAESTHESIA, ANESTHESIA, INTRAVENOUS: outpatient, propofol, lignocaine
Propofol has proven to be a useful anaesthetic induction agent, especially for day case surgery. I It often, however, causes pain on injection. Various strategies have been tried to minimise or prevent this pain. 2 The most successful of these appear to be injection in the antecubital fossa 2 and the addition of lignocaine. 2•3 The latter study,3 however, has been criticised for its use of variable premedication, variable preinduction opioid and lack of controls. 2 This study was designed as a double blind controlled trial to assess the effect of the ad~iition oflignocaine to propofol on injection pam. MATERIALS AND METHODS The study was approved by the hospital ethics committee, and informed consent was obtained from all subjects. The subjects were 100 ASA 1 patients presenting for day case surgery. Those who required premedication were to be excluded. Using a table of random numbers and numbered envelopes, patients were assigned to receive either propofol and 1.0 ml of normal saline or propofol and 1.0 ml of 1% lignocaine plain. The solution was made up by an anaesthetist or registered nurse who was not involved with the case and had to be used within ten minutes of addition. The nature of the additive to the propofol was thus unknown to both patient and anaesthetist. *F.F.A.R.A.C.S .• Staff Specialist. Address for Reprints: Dr. G. N. Newcombe. cl· LyeU McEwin Health Service. Haydown Road. Elizabeth Vale. South Australia 5112. Accepted for publication September 18. 1989
Anaesthesia and intensive Care. Vol. 18. No. I. February'. 1990
No attempt to actively mix the liquids was made. The syringe was not shaken or inverted, but rather allowed to just sit on the anaesthetic workbench. A 23-gauge butterfly needle was inserted into a vein on the dorsum of the hand. Propofol was the first drug given, and speed of injection was standardised, the first 10 ml being given over 20-30 seconds. If the patients had not complained of pain after the initial ten millilitres, they were asked 'Is that painful?' Pain on injection was thus rated as: no pain; pain on questioning after 10 ml; or spontaneous complaint of pain. Postoperatively the subjects were visited by a third anaesthetist and asked to score the injection pain on a 10 cm visual analogue scale. They were also asked if they would be prepared to have the same induction drug agam. RESULTS Seven patients were excluded. The reasons are given in Table 1. Forty-seven patients received lignocaine and forty-six received saline. There were forty-one females in both groups. This preponderence of females is a reflection of the large amount of gynaecological day case surgery done at this hospital. The average age of patients in the TABLE
1
Reasons for patient exclusion Refusal to participate Language difficulties No venous access Mixture left too long Incomplete documentation
2 1
2 1 1
G. N. NEWCOMBE
106 TABLE 2 Response to propojo/ injection
no pain lignocaine 24 saline 6 X2 = 17.10 P=0.00019
pain on questioning 15
spontaneous complaint of pain 8
19
21
saline group was 29 years (range 17-57) and the lignocaine group 28 (range 16-56). The incidence of pain on injection is shown in Table 2. The addition of lignocaine greatly reduced patient discomfort. This was highly significant (Chi 2 = 17.1, 2DF, P=0.00019). Eleven patients (23%) in the lignocaine group had scores of 0, compared with three (65%) in the saline group; The median score for lignocaine was 0.9 and for saline 4.25. The results are presented in Figure 1.
30
~
•
Lignocaine
~
Saline
20
cQ)
~
-... Q.
o
Q)
.c
E
::J
Z
10
o
o to 2
4.1 to 6 Gr. than 6 2.1 to 4 I.-Visual analogue pain scores plotted against number of patients receiving propofol with lignocaine or with saline. FIGURE
Statistical testing of ranking of pain scores also showed a highly significant difference between the two groups (Mann Whitney test statistics 510.5, two-tailed normal, P< 0.00001). When questioned postoperatively two patients in the lignocaine group (4.3%) and thirteen patients in the saline group (29%) wished not to have the same again (Chi 2 = 9.6, 1DF, P < 0.002). DISCUSSION
Propofol is one of the preferred induction agents for day case surgery. Injection pain is a problem, and has been the subject of several reports. Lignocaine pretreatment has not been effective in these studies, which include the Australian multicentre evaluation of propofol. 2-5 One of these studies did report a drop in incidence of pain from 37.5% to 17.5% but this was not statistically significant. 5 The addition of lignocaine to propofol has previously been demonstrated to be effective in reducing the incidence of discomfort. 2.3 The first of these studies 2 makes no mention of blinding the observer. The second 3 was a pilot study and has correctly been criticised 2 for non-randomisation, variable premedication and variable pre-administration opioid. There is no discussion in other reports of how the lignocaine was 'mixed' or 'added'. In this study no active effort was made to mix the additives with the propofol, i.e. the syringe was not shaken, stirred or inverted. This was done to confirm the clinical impression of one of the members of the department that this was an effective method . Our study confirms, in a blinded, randomised and controlled fashion, that the addition of lignocaine to propofol significantly reduces the incidence and severity of pain on injection when propofol is given through a butterfly needle in the dorsum of the hand. No attempt has been made to elucidate the reason(s} for this. A simplistic explanation is that lignocaine anaesthetises the vein wall. Another is that it stabilises the kinin cascade. 2 Even with lignocaine some patients will experience discomfort, one patient in the lignocaine group scoring 10, 'the worst pain you can imagine'. Injection into an anteAnaesthesia and In/ensi.-e Care. Vol. 18. No. I. Februar),. 1990
LIGNOCAINE AND PROPOFOL cubital fossa vein is likely to further reduce the incidence of discomfort. 2,5 SUMMARY This double-blind controlled trial has shown that the addition of lignocaine to propofol modifies the pain on injection of propofol given through a butterfly needle in a vein on the dorsum of the hand. The addition of lignocaine resulted in fewer spontaneous complaints of pain, more patients with no pain, lower pain scores and greater patient acceptance. ACKNOWLEDGEMENTS I would like to thank Richard McDonoughGlenn, the Lyell McEwin Health Service Librarian, and Ms. Coral Arnold for their help with the preparation of this project.
I.
107
REFERENCES Heath PJ, Kennedy DJ, Ogg TW, Dunling C, Gilks WR. Which intravenous induction agent for day surgery? A comparison of propofol, thiopentone, methohexitone and etomidate, Anaesthesia 1988; 43:365-368,
2, Scott RPF, Saunders DA, Norman J, Propofol: Clinical strategies for preventing the pain of injection, Anaesthesia 1988; 43:492-494, 3, Brooker J, Hull CJ, Strattford M, Effect on lignocaine on pain caused by propofol injection: letter Anaesthesia 1985; 40:91-92, 4, Russell WJ, A multicentre evaluation ofpropofol in Australia. Abstracts Australian Society of Anaesthetists AGM 1988. Anaesth Intens Care 1989; 17:97- 106.
5, McCulloch MJ, Lees NW, Assessment and modification of pain on induction with propofol (diprivan), Anaesthesia 1985; 40: 1117-1120.
Does the Radial Arterial Line Degrade the Performance of a Pulse Oximeter? R. W. MORRIS,* M. NAIRNt M. BEAUDOINt
Department of Anaesthesia and Intensive Care, The Prince Henry and Prince of Wales Hospitals, Sydney, Australia SUMMARY
The presence of radial arterial lines may diminish distal digital perfusian, Using a pair of pulse oximeters on the index fingers of cannulated and noncannulated arms the saturation and oximeter pulse strength were assessed. Three hundred paired measurements in fifty consecutive Intensive Care patients were undertaken more than two 'hours after cannula insertion. The pulse strength was 19,7 (SD 6,1) and 19.7 (SD 5.7) on the cannulated and noncannulated sides while the saturation was 97.3 (SD 2.3) and 97.1 (SD 2.4) respectively. These differences are not clinically important and the study demonstrates that reliable pulse oximetry measurements may be made distal ta a radial artery cannula, It is recommended that in each individual the placement of the sensor be such as to ensure the best signal and the most stable saturation readings. Key Words: EQUIPMENT: pulse oximetry, limitations, arterial cannulae, complications; MONITORING: oximetry, arterial blood pressure, measurement
*F.F.A.R.A.C.S., Staff Specialist. tAnaesthetic Technician. tF.F.A.R.A.C.S., Staff Specialist. Address for Reprints: Or. R. W. Morris, Department of Anaesthesia, St. George Hospital, Belgrave Street, Kogarah N.S. W., Australia Accepted for publication August 30, 1989 Anaesthesia and Intensive Care. Vol. 18, No. 1. February, 1990
The pulse oximeter is rapidly becoming accepted as a mandatory monitor during anaesthesia. Various authors have demonstrated that oximetry reveals operative hypoxaemial,2 and that pulse oximetry
