OBJECTIVE: To assess the safety and efficacy of a new patient-maintained propofol system for conscious sedation in dentistry. DESIGN: Prospective clinical trial SETTING: Department of Sedation, Glasgow Dental Hospital and School, 2001 SUBJECTS AND METHODS: Patients scheduled for oral surgery with conscious sedation. Exclusions included ASA IV -V, inability to use the handset, opioid use and severe respiratory disease. INTERVENTIONS: Patients were given intravenous propofol to a level of 1.0 microg/ml (reducing from 1.5 microg/ml) using a target controlled infusion system, they then controlled their sedation level by double-clicking a handset which on each activation increased the propofol concentration by 0.2 microg/ml. MAIN OUTCOME MEASURES: Oxygen saturation, patient satisfaction, and surgeon satisfaction. RESULTS: Twenty patients were recruited, 16 female and four male. Nineteen patients completed sedation and treatment successfully. Mean lowest oxygen saturation was 94%. No patients were over-sedated. All patients successfully used the system to maintain a level of sedation adequate for their comfort. Patient and surgeon satisfaction were consistently high. CONCLUSIONS: Initial experience with this novel system has confirmed safety, patient satisfaction and surgeon satisfaction

AW Murray

C Roseveare

EB Keefe

G N C Kenny

GD Bell

I Smith

J A Leitch

JA Church

JAC Murdoch

JE Charlton

JR Sneyd

M White

MA Quine

MG Irwin

MJ Gillham

N Sutcliffe

English

Leitch, J.A.

Sutcliffe, N.

Kenny, G.N.

Enlighten: Publications

BRITISH DENTAL JOURNAL  VOLUME 194 NO. 1 JANUARY 11 2003 43
Patient-maintained sedation for oral surgery
using a target-controlled infusion of propofol —
a pilot study
J. A. Leitch,1 N. Sutcliffe2 and G. N. C. Kenny 3
Objective To assess the safety and efficacy of a new patient-maintained
propofol system for conscious sedation in dentistry.
Design Prospective clinical trial.
Setting Department of Sedation, Glasgow Dental Hospital and School,
2001.
Subjects and methods Patients scheduled for oral surgery with
conscious sedation. Exclusions included ASA IV -V, inability to use the
handset, opioid use and severe respiratory disease.
Interventions Patients were given intravenous propofol to a level of
1.0 µg/ml (reducing from 1.5 µg/ml) using a target controlled infusion
system, they then controlled their sedation level by double-clicking a
handset which on each activation increased the propofol
concentration by 0.2  µg/ml.
Main outcome measures Oxygen saturation, patient satisfaction, and
surgeon satisfaction.
Results Twenty patients were recruited, 16 female and four male.
Nineteen patients completed sedation and treatment successfully. Mean
lowest oxygen saturation was 94%. No patients were over-sedated. All
patients successfully used the system to maintain a level of sedation
adequate for their comfort. Patient and surgeon satisfaction were
consistently high.
Conclusions Initial experience with this novel system has confirmed
safety, patient satisfaction and surgeon satisfaction.
Patients receiving intravenous conscious sedation for dentistry
within the UK in general practice, community practice and the
hospital service tend to receive incremental doses of intravenous
midazolam administered by an operator-sedationist. Although
there have been no major adverse events in dentistry  the safety of
such a regime has been questioned in other specialities with
reports of up to 13% of patients desaturating to below 80% in the
recovery area following sedation for endoscopy.1 Mortality has
been reported in 0.05% of patients with approximately 60% of this
1Clinical Lecturer, Glasgow Dental Hospital and School, 2Consultant Anaesthetist, HCI
Hospital 3Professor of Anaesthesia, University Department of Anaesthesia, Royal Infirmary,
Glasgow 
*Correspondence to: Mr Jason Leitch, Clinical Lecturer, Glasgow Dental Hospital and
School, 378 Sauchiehall Street, Glasgow G2 3JZ.
E-mail: leitch@bigfoot.com
Refereed paper
Received 08.03.02; Accepted 23.09.02
© British Dental Journal 2003; 194: 43–35
being due to hypoxaemia.1-4 No such serious outcomes have been
reported in dentistry.
In anaesthesia, target-controlled infusion (TCI) of propofol is
gaining wide popularity. The system uses a pharmacokinetic
model to achieve and maintain a selected target blood propofol
concentration. The system has been further developed to incorpo-
rate a handset so that patients can titrate their own blood propofol
concentrations to a sedation level appropriate to themselves. This
combines the benefits of TCI with the well-established safety of a
patient-controlled feedback loop and has been termed patient-
maintained sedation (PMS). 
Low dose propofol has been shown to have satisfactory anxi-
olytic properties when used as a sedative.5 It has been evaluated in
a variety of intermittent bolus and infusion regimes.6-8
Patient-controlled sedation with propofol TCI has been shown
to be safe and effective in reducing pre-operative anxiety levels
when used to provide intra-operative sedation for patients under-
going surgery, with no patients becoming oversedated, premedica-
tion for day case patients and most recently in patients undergoing
endoscopic examination.9-11
Propofol has several pharmacokinetic parameters that poten-
tially make it a superior sedative agent to midazolam; more rapid
onset and offset being two. However its routine use has been
restricted to anaesthetists, as in high doses, general anaesthesia is
produced with possible loss of the patient's patent airway. 
Conscious sedation for minor oral surgery procedures is becom-
ing increasingly popular as general anaesthesia becomes less so. In
combination with local anaesthesia it potentially forms a pain-free
and anxiety-free technique for both the patient and the surgical
team. Any new drug delivery system must be carefully assessed for
safety and efficacy in this specific environment.
This study assesses the first use of this patient-maintained seda-
tion system using TCI propofol for oral surgery in 20 patients as a
sedative technique for these procedures.
MATERIALS AND METHODS
The project was approved by the Hospital Ethics Committee. Twen-
ty patients who were referred for oral surgery with conscious seda-
tion were asked to participate in a study using patient-maintained
propofol as the sedative technique. Recruitment was not selective
and therefore included a range of anxiety levels from those phobic
of dentistry to those anxious about surgical procedures. Written
● Intravenous sedation with Midazolam is well established but is not suitable for all clinical
situations.
● Patient-maintained sedation with propofol may offer an alternative to midazolam.
● The system is safe and reproducible.
● Patient and surgeon satisfaction are high.
● Recovery is fast and uneventful.
I N  B R I E F
RESEARCH
RESEARCH
44 BRITISH DENTAL JOURNAL  VOLUME 194 NO. 1 JANUARY 11 2003
consent was obtained after a full explanation of the sedative tech-
nique and the surgery involved. Any patient considered fit for
sedation was recruited. All patients were required to bring an
escort and standard post-operative sedation instructions were
given. These included no driving for twelve hours and resting at
home for the rest of the day. Patients were not starved prior to
treatment but were advised to have a light meal two hours before
their appointment. Exclusion criteria included inability to use the
handset, opioid use and severe respiratory disease. 
Venous access was obtained and baseline observations were
obtained of blood pressure, oxygen saturation and heart rate.
Propofol TCI was delivered via a Graseby 3400 infusion pump con-
trolled by a microprocessor system programmed with the pharma-
cokinetic data describing the distribution and elimination of
propofol.10,12 The system displays the calculated effect-site, or the
theoretical brain concentration, in addition to the target blood
concentration of propofol, based on the patient's age and weight
which are entered into the microprocessor. Connection of a hand-
set to the microprocessor allows the patient to increase their target
blood concentration of propofol (Figure 1).
Propofol (1% with lidocaine 20 mg per 50 ml to decrease pain
on injection) was started at an initial target blood concentration of
1.5 µg/ml. When the microprocessor estimated the effect-site con-
centration to be 1.0 µg the target was reduced to 1.0 µg and the
patient was instructed to ‘double-press' the button as often as nec-
essary. They were advised to sedate themselves to an appropriate
level at which they would allow local anaesthesia to be adminis-
tered.
Successful activation of the handset by double pressing the but-
ton within one second would increase the target blood concentra-
tion of propofol by 0.2 µg/ml. There was a lock-out period of two
minutes during which no further target increases were possible.
The maximum permissible target blood concentration of propofol
was 3.0 µg/ml. If no successful demands were detected in six min-
utes the microprocessor would automatically reduce the target
blood concentration by 0.2 µg/ml.
Once the patient considered themselves ready, they received a
standard dental local anaesthetic (2% lidocaine with 1:80,000
adrenaline) and the surgery was carried out. They were advised to
press the button at any stage if they wanted to be more sedated.
The patients were monitored throughout with pulse oximetry
and measurements of heart rate and arterial oxygen saturation
were recorded every five minutes. Blood pressure readings were
recorded pre-operatively and prior to discharge. Any emergency
interventions were noted. Patients were taken to a dedicated recov-
ery area after their surgery was complete where they were moni-
tored throughout with pulse oximetry by a trained dental nurse.
Once the patient was judged fit for discharge using a modified
Romberg's test and by demonstrating a steady, unaided walk
across the recovery room they completed a questionnaire designed
to assess patient recall and satisfaction with the technique. The
surgeon also completed a questionnaire regarding ease of under-
taking the procedure and patient cooperation.
A note was made of start time, the time the patient-controlled
button was enabled, surgery start time, surgery finish time and dis-
charge time. The lowest recorded arterial oxygen saturation was
also noted.
RESULTS
Of the 20 patients, 19 completed their treatment satisfactorily and
maintained a level of sedation which was both adequate for their
anxiety control and for completion of the procedure. There were
16 female and four male patients. The mean age was 31 years with
a range from 12 to 58. Fourteen patients were ASA I, five were
ASA II and one was ASA III. 
One of the twenty patients was a known epileptic and on com-
pletion of the surgery suffered three progressively shorter grand
mal seizures with increasing time between each. She recovered
spontaneously on each occasion and no measures other than mon-
itoring and reassurance were required. She was transferred by
ambulance to the local accident and emergency department where
she was supervised for two hours. She suffered no further seizures
and was discharged home without further problems. She could not
be considered to have completed the study since it was impossible
to complete the post-operative questionnaire.
All surgical procedures were carried out by the same surgeon
and a variety of surgical procedures were performed (Table 1).
The mean procedure time was 15.4 minutes (4–30 mins). The
mean time to local anaesthetic was 8.3 minutes (5–16 mins), to dis-
charge was 47.4 mins (35–80 mins) and from end of procedure to
discharge was 22.2 minutes (10–45 mins).
There were no cases of haemodynamic instability and the mean
lowest oxygen saturation was 94%. One patient had a transient
saturation of 87% which was corrected easily with supplemental
oxygen at 2 l/min via nasal cannulae. This patient was the only
ASA III patient in the study. The lowest arterial oxygen saturation
for each patient is shown in Figure 2. There were no significant
changes in heart rate or blood pressure. 
All twenty patients used the system satisfactorily to maintain a
level of sedation which was adequate for their comfort and the
completion of the surgical procedure. The recorded effect-site con-
centrations of propofol did not vary much immediately before the
injection of local anaesthetic but showed a three-fold variation by
the end of the surgical procedure. (Table 2).
Of the nineteen patients who completed a post-operative ques-
tionnaire all were happy with the sedation they received and
would have the same system again. No patients reported nausea at
any stage. Four experienced pain on injection of the propofol and
six reported some pain during the procedure. Using a four point
Figure 1 Patient maintained
sedation equipment including
handset.
Table 1 Surgical procedures performed
Surgical Procedure Number
Third molar extraction 12
Multiple extractions 4
Impacted canine removal 2
Apicectomy 1
Table 2 Effect-site concentration of propofol (mcg/ml) at principal stages of
procedure
Time Median Range
Immediately before LA 1.1 1-1.5
At end of surgical procedure 2 0.9-2.8
RESEARCH
BRITISH DENTAL JOURNAL  VOLUME 194 NO. 1 JANUARY 11 2003 45
suggested that this is dose related. Willingness of all patients in the
present study to have a repeat procedure with the PMS technique
would suggest that the recall of the patients in this study is a posi-
tive outcome. Although oral surgery tends to be a one-off proce-
dure more general dentistry can often require repeat visits. The
willingness to repeat the experience is a distinct advantage. 
The system was found to be safe in that no patient suffered seri-
ous desaturation. The only patient with a saturation below 90%
was promptly and easily treated with supplemental oxygen. In pre-
vious studies all patients have received supplemental oxygen,9-11
but our data would suggest this is unnecessary in our group of
patients. No patients were oversedated and all maintained verbal
contact throughout the procedure. 
The one patient who did not complete the study did however
complete her surgery and sedation. All the difficulties were post-
operatively. Caution with propofol in epilepsy is well document-
ed13 and our findings would suggest this system needs significant
care in epileptic patients. 
The surgeon rated cooperation as ‘very good' in 84% of cases
which is very encouraging. The only case in which cooperation
was a problem was the only patient under 16 years old in the pres-
ent study. This would fit with reports and should lead to caution in
using the system in those under 16.
It is too early to recommend this system for wide use but initial
experience has confirmed both surgeon and patient satisfaction
were high. These results are encouraging and in combination with
the increasing literature on the subject, the next stage is a prospec-
tive, randomised controlled trial of this new system against the
more established technique of administering incremental doses of
midazolam. The end-point is a safe and effective operator-seda-
tionist system.
1. Quine M A, Bell G D, McCloy R F, Charlton J E, Devlin H B, Hopkins A. Prospective audit
of upper gastrointestinal endoscopy in two regions of England: safety, staffing and
sedation methods. Gut 1995; 95: 462-467.
2. Bell G D. Review article: premedication and intravenous sedation for upper
gastrointestinal endoscopy. Ailment Pharmacol Ther 1990; 4: 103-122.
3. Murray A W, Morran C G, Kenny G N, Macfarlane P, Anderson J R. Examination of
cardiorespiratory changes during upper gastrointestinal endoscopy. Comparison of
monitoring of arterial oxygen saturation, arterial pressure and the electrocardiogram.
Anaesthesia 1991; 46: 181-184.
4. Charlton J E. Monitoring and supplemental oxygen during endoscopy. Br Med J 1995;
310: 886-887.
5. Smith I, Monk T G, White P F, Ding Y. Propofol infusion during regional anaesthesia:
sedative, amnestic and anxiolytic properties. Anesth Analg 1994; 79: 313-319.
6. Keefe E B. Sedation and Analgesia for Endoscopy. Gastroenterology 1995; 108: 932-
934.
7. Church J A, Stanton P D, Kenny G N C, Anderson J R. Propofol for sedation during
endoscopy: assessment of a computer-controlled infusion system. Gastrointest
Endosc 1991; 37: 175-179.
8. Roseveare C, Seavell C, Patel P, Criswell J, Shepherd H. Patient-controlled sedation
with propofol and alfentanil during colonoscopy: a pilot study. Endosc 1998; 30:
482-483.
9. Irwin M G, Thompson N, Kenny G N C. Patient-maintained propofol sedation.
Anaesthesia 1997; 52: 525-530.
10. Murdoch J A C, Kenny G N C. Patient-maintained propofol sedation as premedication
in day-case surgery: assessment of a target-controlled system. Br J Anaesth 1999; 82:
429-431.
11. Gillham M J, Hutchinson R C, Cater R, Kenny, G N. Patient-controlled sedation for
ERCP using a target-controlled infusion of propofol: a pilot study. Gastrointestinal
Endosc 2001; 54: 14-17.
12. White M, Kenny G N C. Intravenous propofol anaesthesia using a computerised
infusion system. Anaesthesia 1990; 45: 204-209.
13. Sneyd J R. Propofol and epilepsy. Br J Anaesth 1999; 82: 168-169.
scale (no recall, not unpleasant, unpleasant, horrible) 18 patients
found the whole procedure ‘not unpleasant' and only one patient
described it as ‘unpleasant'. All patients recalled arriving in the
dental surgery and the intravenous cannulation, 18 recalled injec-
tion of the local anaesthesia and seventeen reported remembering
aspects of the surgical procedure. The patient who could not recall
the local anaesthetic could recall the surgery.
Using a four point scale (easy, mild difficulty, difficult, very dif-
ficult) the surgeon rated three (16%) as ‘easy', ten (53%) as ‘mild
difficulty' and six (32%) as ‘difficult'. Using another four point
scale (very good, good, average, minimal) the surgeon rated
patient co-operation as ‘very good' in sixteen cases (84%), ‘good'
in two cases (10%) and ‘minimal' in one case (5%). The case rated
as ‘minimal' was a twelve-year-old for removal of four first
molars.
A number of patients spontaneously volunteered when asked if
they had any further comments that they liked the control they
had over their sedation.
DISCUSSION
Initial evaluation of this patient-maintained sedation system for
oral surgery procedures has provided useful practical data. The
system was used successfully and treatment was completed in all
20 patients. The median effect-site blood concentration required
for adequate sedation was lower than in previous studies.9-11 No
patient reached the maximum level of 3.0 µg/ml. Previous studies
using endoscopy patients have reported levels of up to 4.5 µg/ml.9
This observation is almost certainly due to the good local anaes-
thetic blocks achievable for oral surgery procedures. 
Sedation in dentistry tends to be provided with incremental
doses of benzodiazepines. This technique is associated with a high
degree of amnesia. The results from the present study suggest that
a high proportion of patients treated with patient-maintained
propofol sedation at these levels recall aspects of their procedure
and more importantly they report it as not unpleasant. This may be
a distinct advantage in trying to educate patients about the pain-
less nature of modern dentistry. Previous reports, principally of
endoscopy, have shown higher levels of amnesia and it has been
0
1
2
3
4
5
6
No.
87 92 93 94 95 96 97
Arterial oxygen saturation (%) 
Figure 2  Lowest arterial oxygen saturation


Patient-maintained sedation for oral surgery using a target-controlled infusion of propofol - a pilot study

Crossref

Patient-maintained sedation for oral surgery using a target-controlled infusion of propofol – a pilot study

Enlighten

BRITISH DENTAL JOURNAL  VOLUME 194 NO. 1 JANUARY 11 2003 43Patient-maintained sedation for oral surgeryusing a target-controlled infusion of propofol —a pilot studyJ. A. Leitch,1 N. Sutcliffe2 and G. N. C. Kenny 3Objective To assess the safety and efficacy of a new patient-maintainedpropofol system for conscious sedation in dentistry.Design Prospective clinical trial.Setting Department of Sedation, Glasgow Dental Hospital and School,2001.Subjects and methods Patients scheduled for oral surgery withconscious sedation. Exclusions included ASA IV -V, inability to use thehandset, opioid use and severe respiratory disease.Interventions Patients were given intravenous propofol to a level of1.0 µg/ml (reducing from 1.5 µg/ml) using a target controlled infusionsystem, they then controlled their sedation level by double-clicking ahandset which on each activation increased the propofolconcentration by 0.2  µg/ml.Main outcome measures Oxygen saturation, patient satisfaction, andsurgeon satisfaction.Results Twenty patients were recruited, 16 female and four male.Nineteen patients completed sedation and treatment successfully. Meanlowest oxygen saturation was 94%. No patients were over-sedated. Allpatients successfully used the system to maintain a level of sedationadequate for their comfort. Patient and surgeon satisfaction wereconsistently high.Conclusions Initial experience with this novel system has confirmedsafety, patient satisfaction and surgeon satisfaction.Patients receiving intravenous conscious sedation for dentistrywithin the UK in general practice, community practice and thehospital service tend to receive incremental doses of intravenousmidazolam administered by an operator-sedationist. Althoughthere have been no major adverse events in dentistry  the safety ofsuch a regime has been questioned in other specialities withreports of up to 13% of patients desaturating to below 80% in therecovery area following sedation for endoscopy.1 Mortality hasbeen reported in 0.05% of patients with approximately 60% of this1Clinical Lecturer, Glasgow Dental Hospital and School, 2Consultant Anaesthetist, HCIHospital 3Professor of Anaesthesia, University Department of Anaesthesia, Royal Infirmary,Glasgow *Correspondence to: Mr Jason Leitch, Clinical Lecturer, Glasgow Dental Hospital andSchool, 378 Sauchiehall Street, Glasgow G2 3JZ.E-mail: leitch@bigfoot.comRefereed paperReceived 08.03.02; Accepted 23.09.02© British Dental Journal 2003; 194: 43–35being due to hypoxaemia.1-4 No such serious outcomes have beenreported in dentistry.In anaesthesia, target-controlled infusion (TCI) of propofol isgaining wide popularity. The system uses a pharmacokineticmodel to achieve and maintain a selected target blood propofolconcentration. The system has been further developed to incorpo-rate a handset so that patients can titrate their own blood propofolconcentrations to a sedation level appropriate to themselves. Thiscombines the benefits of TCI with the well-established safety of apatient-controlled feedback loop and has been termed patient-maintained sedation (PMS). Low dose propofol has been shown to have satisfactory anxi-olytic properties when used as a sedative.5 It has been evaluated ina variety of intermittent bolus and infusion regimes.6-8Patient-controlled sedation with propofol TCI has been shownto be safe and effective in reducing pre-operative anxiety levelswhen used to provide intra-operative sedation for patients under-going surgery, with no patients becoming oversedated, premedica-tion for day case patients and most recently in patients undergoingendoscopic examination.9-11Propofol has several pharmacokinetic parameters that poten-tially make it a superior sedative agent to midazolam; more rapidonset and offset being two. However its routine use has beenrestricted to anaesthetists, as in high doses, general anaesthesia isproduced with possible loss of the patient's patent airway. Conscious sedation for minor oral surgery procedures is becom-ing increasingly popular as general anaesthesia becomes less so. Incombination with local anaesthesia it potentially forms a pain-freeand anxiety-free technique for both the patient and the surgicalteam. Any new drug delivery system must be carefully assessed forsafety and efficacy in this specific environment.This study assesses the first use of this patient-maintained seda-tion system using TCI propofol for oral surgery in 20 patients as asedative technique for these procedures.MATERIALS AND METHODSThe project was approved by the Hospital Ethics Committee. Twen-ty patients who were referred for oral surgery with conscious seda-tion were asked to participate in a study using patient-maintainedpropofol as the sedative technique. Recruitment was not selectiveand therefore included a range of anxiety levels from those phobicof dentistry to those anxious about surgical procedures. Written● Intravenous sedation with Midazolam is well established but is not suitable for all clinicalsituations.● Patient-maintained sedation with propofol may offer an alternative to midazolam.● The system is safe and reproducible.● Patient and surgeon satisfaction are high.● Recovery is fast and uneventful.I N  B R I E FRESEARCHRESEARCH44 BRITISH DENTAL JOURNAL  VOLUME 194 NO. 1 JANUARY 11 2003consent was obtained after a full explanation of the sedative tech-nique and the surgery involved. Any patient considered fit forsedation was recruited. All patients were required to bring anescort and standard post-operative sedation instructions weregiven. These included no driving for twelve hours and resting athome for the rest of the day. Patients were not starved prior totreatment but were advised to have a light meal two hours beforetheir appointment. Exclusion criteria included inability to use thehandset, opioid use and severe respiratory disease. Venous access was obtained and baseline observations wereobtained of blood pressure, oxygen saturation and heart rate.Propofol TCI was delivered via a Graseby 3400 infusion pump con-trolled by a microprocessor system programmed with the pharma-cokinetic data describing the distribution and elimination ofpropofol.10,12 The system displays the calculated effect-site, or thetheoretical brain concentration, in addition to the target bloodconcentration of propofol, based on the patient's age and weightwhich are entered into the microprocessor. Connection of a hand-set to the microprocessor allows the patient to increase their targetblood concentration of propofol (Figure 1).Propofol (1% with lidocaine 20 mg per 50 ml to decrease painon injection) was started at an initial target blood concentration of1.5 µg/ml. When the microprocessor estimated the effect-site con-centration to be 1.0 µg the target was reduced to 1.0 µg and thepatient was instructed to ‘double-press' the button as often as nec-essary. They were advised to sedate themselves to an appropriatelevel at which they would allow local anaesthesia to be adminis-tered.Successful activation of the handset by double pressing the but-ton within one second would increase the target blood concentra-tion of propofol by 0.2 µg/ml. There was a lock-out period of twominutes during which no further target increases were possible.The maximum permissible target blood concentration of propofolwas 3.0 µg/ml. If no successful demands were detected in six min-utes the microprocessor would automatically reduce the targetblood concentration by 0.2 µg/ml.Once the patient considered themselves ready, they received astandard dental local anaesthetic (2% lidocaine with 1:80,000adrenaline) and the surgery was carried out. They were advised topress the button at any stage if they wanted to be more sedated.The patients were monitored throughout with pulse oximetryand measurements of heart rate and arterial oxygen saturationwere recorded every five minutes. Blood pressure readings wererecorded pre-operatively and prior to discharge. Any emergencyinterventions were noted. Patients were taken to a dedicated recov-ery area after their surgery was complete where they were moni-tored throughout with pulse oximetry by a trained dental nurse.Once the patient was judged fit for discharge using a modifiedRomberg's test and by demonstrating a steady, unaided walkacross the recovery room they completed a questionnaire designedto assess patient recall and satisfaction with the technique. Thesurgeon also completed a questionnaire regarding ease of under-taking the procedure and patient cooperation.A note was made of start time, the time the patient-controlledbutton was enabled, surgery start time, surgery finish time and dis-charge time. The lowest recorded arterial oxygen saturation wasalso noted.RESULTSOf the 20 patients, 19 completed their treatment satisfactorily andmaintained a level of sedation which was both adequate for theiranxiety control and for completion of the procedure. There were16 female and four male patients. The mean age was 31 years witha range from 12 to 58. Fourteen patients were ASA I, five wereASA II and one was ASA III. One of the twenty patients was a known epileptic and on com-pletion of the surgery suffered three progressively shorter grandmal seizures with increasing time between each. She recoveredspontaneously on each occasion and no measures other than mon-itoring and reassurance were required. She was transferred byambulance to the local accident and emergency department whereshe was supervised for two hours. She suffered no further seizuresand was discharged home without further problems. She could notbe considered to have completed the study since it was impossibleto complete the post-operative questionnaire.All surgical procedures were carried out by the same surgeonand a variety of surgical procedures were performed (Table 1).The mean procedure time was 15.4 minutes (4–30 mins). Themean time to local anaesthetic was 8.3 minutes (5–16 mins), to dis-charge was 47.4 mins (35–80 mins) and from end of procedure todischarge was 22.2 minutes (10–45 mins).There were no cases of haemodynamic instability and the meanlowest oxygen saturation was 94%. One patient had a transientsaturation of 87% which was corrected easily with supplementaloxygen at 2 l/min via nasal cannulae. This patient was the onlyASA III patient in the study. The lowest arterial oxygen saturationfor each patient is shown in Figure 2. There were no significantchanges in heart rate or blood pressure. All twenty patients used the system satisfactorily to maintain alevel of sedation which was adequate for their comfort and thecompletion of the surgical procedure. The recorded effect-site con-centrations of propofol did not vary much immediately before theinjection of local anaesthetic but showed a three-fold variation bythe end of the surgical procedure. (Table 2).Of the nineteen patients who completed a post-operative ques-tionnaire all were happy with the sedation they received andwould have the same system again. No patients reported nausea atany stage. Four experienced pain on injection of the propofol andsix reported some pain during the procedure. Using a four pointFigure 1 Patient maintainedsedation equipment includinghandset.Table 1 Surgical procedures performedSurgical Procedure NumberThird molar extraction 12Multiple extractions 4Impacted canine removal 2Apicectomy 1Table 2 Effect-site concentration of propofol (mcg/ml) at principal stages ofprocedureTime Median RangeImmediately before LA 1.1 1-1.5At end of surgical procedure 2 0.9-2.8RESEARCHBRITISH DENTAL JOURNAL  VOLUME 194 NO. 1 JANUARY 11 2003 45suggested that this is dose related. Willingness of all patients in thepresent study to have a repeat procedure with the PMS techniquewould suggest that the recall of the patients in this study is a posi-tive outcome. Although oral surgery tends to be a one-off proce-dure more general dentistry can often require repeat visits. Thewillingness to repeat the experience is a distinct advantage. The system was found to be safe in that no patient suffered seri-ous desaturation. The only patient with a saturation below 90%was promptly and easily treated with supplemental oxygen. In pre-vious studies all patients have received supplemental oxygen,9-11but our data would suggest this is unnecessary in our group ofpatients. No patients were oversedated and all maintained verbalcontact throughout the procedure. The one patient who did not complete the study did howevercomplete her surgery and sedation. All the difficulties were post-operatively. Caution with propofol in epilepsy is well document-ed13 and our findings would suggest this system needs significantcare in epileptic patients. The surgeon rated cooperation as ‘very good' in 84% of caseswhich is very encouraging. The only case in which cooperationwas a problem was the only patient under 16 years old in the pres-ent study. This would fit with reports and should lead to caution inusing the system in those under 16.It is too early to recommend this system for wide use but initialexperience has confirmed both surgeon and patient satisfactionwere high. These results are encouraging and in combination withthe increasing literature on the subject, the next stage is a prospec-tive, randomised controlled trial of this new system against themore established technique of administering incremental doses ofmidazolam. The end-point is a safe and effective operator-seda-tionist system.1. Quine M A, Bell G D, McCloy R F, Charlton J E, Devlin H B, Hopkins A. Prospective auditof upper gastrointestinal endoscopy in two regions of England: safety, staffing andsedation methods. Gut 1995; 95: 462-467.2. Bell G D. Review article: premedication and intravenous sedation for uppergastrointestinal endoscopy. Ailment Pharmacol Ther 1990; 4: 103-122.3. Murray A W, Morran C G, Kenny G N, Macfarlane P, Anderson J R. Examination ofcardiorespiratory changes during upper gastrointestinal endoscopy. Comparison ofmonitoring of arterial oxygen saturation, arterial pressure and the electrocardiogram.Anaesthesia 1991; 46: 181-184.4. Charlton J E. Monitoring and supplemental oxygen during endoscopy. Br Med J 1995;310: 886-887.5. Smith I, Monk T G, White P F, Ding Y. Propofol infusion during regional anaesthesia:sedative, amnestic and anxiolytic properties. Anesth Analg 1994; 79: 313-319.6. Keefe E B. Sedation and Analgesia for Endoscopy. Gastroenterology 1995; 108: 932-934.7. Church J A, Stanton P D, Kenny G N C, Anderson J R. Propofol for sedation duringendoscopy: assessment of a computer-controlled infusion system. GastrointestEndosc 1991; 37: 175-179.8. Roseveare C, Seavell C, Patel P, Criswell J, Shepherd H. Patient-controlled sedationwith propofol and alfentanil during colonoscopy: a pilot study. Endosc 1998; 30:482-483.9. Irwin M G, Thompson N, Kenny G N C. Patient-maintained propofol sedation.Anaesthesia 1997; 52: 525-530.10. Murdoch J A C, Kenny G N C. Patient-maintained propofol sedation as premedicationin day-case surgery: assessment of a target-controlled system. Br J Anaesth 1999; 82:429-431.11. Gillham M J, Hutchinson R C, Cater R, Kenny, G N. Patient-controlled sedation forERCP using a target-controlled infusion of propofol: a pilot study. GastrointestinalEndosc 2001; 54: 14-17.12. White M, Kenny G N C. Intravenous propofol anaesthesia using a computerisedinfusion system. Anaesthesia 1990; 45: 204-209.13. Sneyd J R. Propofol and epilepsy. Br J Anaesth 1999; 82: 168-169.scale (no recall, not unpleasant, unpleasant, horrible) 18 patientsfound the whole procedure ‘not unpleasant' and only one patientdescribed it as ‘unpleasant'. All patients recalled arriving in thedental surgery and the intravenous cannulation, 18 recalled injec-tion of the local anaesthesia and seventeen reported rememberingaspects of the surgical procedure. The patient who could not recallthe local anaesthetic could recall the surgery.Using a four point scale (easy, mild difficulty, difficult, very dif-ficult) the surgeon rated three (16%) as ‘easy', ten (53%) as ‘milddifficulty' and six (32%) as ‘difficult'. Using another four pointscale (very good, good, average, minimal) the surgeon ratedpatient co-operation as ‘very good' in sixteen cases (84%), ‘good'in two cases (10%) and ‘minimal' in one case (5%). The case ratedas ‘minimal' was a twelve-year-old for removal of four firstmolars.A number of patients spontaneously volunteered when asked ifthey had any further comments that they liked the control theyhad over their sedation.DISCUSSIONInitial evaluation of this patient-maintained sedation system fororal surgery procedures has provided useful practical data. Thesystem was used successfully and treatment was completed in all20 patients. The median effect-site blood concentration requiredfor adequate sedation was lower than in previous studies.9-11 Nopatient reached the maximum level of 3.0 µg/ml. Previous studiesusing endoscopy patients have reported levels of up to 4.5 µg/ml.9This observation is almost certainly due to the good local anaes-thetic blocks achievable for oral surgery procedures. Sedation in dentistry tends to be provided with incrementaldoses of benzodiazepines. This technique is associated with a highdegree of amnesia. The results from the present study suggest thata high proportion of patients treated with patient-maintainedpropofol sedation at these levels recall aspects of their procedureand more importantly they report it as not unpleasant. This may bea distinct advantage in trying to educate patients about the pain-less nature of modern dentistry. Previous reports, principally ofendoscopy, have shown higher levels of amnesia and it has been0123456No.87 92 93 94 95 96 97Arterial oxygen saturation (%) Figure 2  Lowest arterial oxygen saturation

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Patient-maintained sedation for oral surgery using a target-controlled infusion of propofol - a pilot study

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