ARTICLE
Auteur(s) : C
Motamed, G Salazar, J-L Bourgain
Institute Gustave-Roussy, Department of anesthesia, 39, rue
Camille-Desmoulins, 94805 Villejuif Cedex, France
Article reçu le 22 Octobre 2009, accepté le 10 Avril 2010
Introduction
In recent years, high importance is given to the prevention of
postoperative pain including anticipated intra-operative pain
management but also minimally invasive surgery (laparoscopy) [1-3].
There is still a percentage of patients (up to 80%) who still
suffer from mild to severe postoperative pain especially upon
arrival in the Postanesthetic Care Unit (PACU) which need immediate
intervention [4] while progress should also to be made on education
of healthcare categories [5, 6]. Adverse effects of postoperative
pain are well known: significant initial distress, negative effect
on immune function, wound healing and perhaps even chronic post
surgical pain syndrome in case of very high postoperative pain
scores [7, 8].
Anticipated postoperative pain management protocol is our
current clinical practice since several years. Inaddition, our
department saves all anesthesia and PACU events into an important
database (DEIO) including more than 57,000 cases since 2001.
Therefore, as part of quality-assurance program, this study was
designed to assess the incidence of patients having very high
postoperative pain scores, in the PACU and to identify independent
factors of severe postoperative pain by comparing these patients to
another group of patients having a similar type of surgery in an
adjacent period.
Methods
After anesthesia and PACU stay, all the information concerning
events and monitoring trend curves are saved into a powerful data
base fuelled with a computerized anesthesia record system (ARK
DEIO-GE ™). Our primary objective was to evaluate the incidence of
patients having severe postoperative pain in PACU despite
anticipation and to assess their demographic characteristics. Our
secondary objective was to detect significant factor contributing
to these high postoperative pain scores by comparison to a similar
population not having severe pain. Our local ethical board
committee approved the use of our database to perform this
retrospective case-controlled analysis. Patients approved these
types of study by signing their acceptation to participate during
one of the first consultations in our hospital.
About 6,000 patients transit in our PACU per year. As a routine
care, all patients undergoing surgical or interventional radiology
procedures under general or regional anesthesia transit via the
PACU, in addition to these cases some patients having local
anesthesia only might transit the PACU for surveillance in a case
by case basis depending on the type of the procedure. All patients
had a standardised evaluation: temperature, pain score in a
5 grades numerical scale at rest (0 no pain, 1 mild pain,
2 moderate pain, 3 severe pain, 4 very severe pain)
and a 4 grades sedation scale (0 alert, 1 sometimes
drowsy easily aroused, 2 often drowsy easily aroused,
3 often drowsy difficult to arouse). Nurses enter these data
manually in our computerised record via predefined lists. Other
criteria such as blood pressure, pulse oximetry, pulse rate are
automatically stored.
Postoperative pain was anticipated by preoperative analgesic
administration using standardised multimodal protocol as follows:
systematic use of moderate pain killer such as paracetamol,
tramadol, nefopam, and IV morphine in case of the use of
remifentanil in surgery known to yield severe pain, but also the
intraoperative injection of local anesthetics through epidural or
perineural injection [9]. The dose of intraoperative morphine in
our setting depends on the type of anticipated postoperative pain
(none, moderate or severe) and varies from 0.05 to 0.2mg/kg,
according to type surgery and preoperative opiate treatment [10],
local anaesthetics through epidural and peripheral catheters for
all patients was injected thirty minutes before the end of surgery.
Other drugs such as ketamine or non steroidal anti inflammatory
drugs were also used at the discretion of the anesthetistt in
charge in the PACU in rescue situations. More than 99% of the
patients are extubated in the operating room after control
neuromuscular blockade (NMT Datex GE™) in addition to other
criteria including temperature. For PACU discharge, the following
parameters are systematically checked and recorded: pain score,
sedation score, temperature and vital signs such as blood pressure,
oxygen saturation, pulsation, respiratory rate and postoperative
nausea and vomiting status. Preoperative events, including
preoperative anesthetic evaluation and patient's history are not
linked to the data base. Morphine titration in PACU is started when
patients has a pain score of 3 or 4. Titration starts
with boluses of 2 or 3 mg (depending on age) and are
renewed every 7min, it is stopped when pain scores decrease to
2 there is no limit of IV morphine titration.
During the period 2006-2007, patients were selected from the
data base for having a numeric pain score-of 4. The control group
was selected using similar age, type of surgery in an adjacent time
period (before or after one week maximum).
Emergency surgical patients were not considered because most of
them were directly managed in the intensive care unit upon
completion of surgery.
Several parameters were compared between the two groups: pain
scores at the arrival and before leaving PACU,
- – Morphine consumption defined as the total amount of
morphine injected during anesthesia and recovery period.
- – Preoperative treatment classified into groups:
cardiovascular, psychoactive, analgesic (opiates and non-opiates),
anti-inflammatory.
Epidural failure was considered when additional IV morphine
injection was necessary to decrease postoperative pain related to
surgery as was peripheral nerve block failure. Student t test, Mann
Whitney rank sum test, Χ2 test or Fischer exact test
were used to compare data with Sigmastat statistical software for
Windows V3 (USA).
Results
Data were obtained from a total of 12,510 patients, 6,495 in 2006
and 6,015 in 2007. Exhaustivity (number of patients with at least a
record of one pain score divided by the number of procedures) was
91% in 2006 and 94% in 2007.
Demographic characteristics are represented in Table 1; no significant difference was
detected between groups. Duration of surgery was not significantly
different between groups (table 1).
A total of 78 patients (0.6%) had pain score of 4 upon
arrival in the PACU, (33 in 2006 and 45 in 2007). All type of
procedures performed in our institution were involved:
oto-rhinolaryngology (21%), interventional radiology (15%),
gynaecological (8%), abdominal (23%), breast surgery (17%) and
other peripheral surgery (16%). The controlled group had an initial
pain score of 1.6±1.1, (p<0.05). In PACU, morphine consumption
13.6±6mg was significantly higher in the cases study group
compared to the controlled group 6.9±7mg (p<0.05) (table 2). Among preoperative treatment,
consumption of psychoactive medication: (benzodiazepine and/or
antidepressant) was the only risk factor of severe postoperative
pain.
Intra operative parameters were comparable between the two
groups: number of patients receiving remifentanil or sufentanil and
the respective dosage. Anticipated analgesic treatment was not
significantly different between the two groups, including at least
two means of anticipated postoperative pain (paracetamol, tramadol
or nefopam). Those having epidural or perineural analgesia had an
injection at skin closure. No statistically significant difference
was noticed comparing sedation and pain score when leaving the
PACU, (table 3).
Table 1 Demographic characteristics.
|
Cases (n = 78)
|
Controlled (n = 78)
|
|
Age (yr)
|
50±13
|
50±11
|
|
Weight (kg)
|
65±12
|
65±16
|
|
Height (cm)
|
166±9
|
165±9
|
|
Sex (M/F)
|
38/40
|
40/38
|
|
Duration of surgery (min)
|
165±145
|
178±139
|
|
Type of surgery
|
2006
|
2007
|
2006
|
2007
|
|
Head and Neck surgery
|
9
|
7
|
9
|
7
|
|
Interventional radiology
|
5
|
7
|
5
|
7
|
|
Gynecology laparoscopy included (LI)
|
1
|
5
|
3
|
3
|
|
Hepato gastroenteral surgery LI
|
8
|
9
|
7
|
10
|
|
Breast surgery
|
6
|
8
|
6
|
8
|
|
Others (peripheral sarcoma and dermatology)
|
4
|
9
|
3
|
10
|
|
Sum
|
33
|
45
|
33
|
45
|
Table 2 Pre operative pain medication and
intraoperative opioid requirements, and postoperative pain
anticipation.
|
Cases (n=78)
|
Controlled (n=78)
|
|
Preoperative opiate treatment (n° patients)
|
3/78
|
4/78
|
|
Preoperative non opiate pain medication (n° patients)
|
5/78
|
4/78
|
|
Preoperative use of psychoactive medications:
benzodiazepine, antidepressant (n° patients)
|
13
|
2*
|
|
Intraoperative sufentanil (n° patients)
|
16/78
|
16/78
|
|
Mean sufentanil consumption μg
|
19±7
|
15±4
|
|
Intraoperative remifentanil (n° patients)
|
62/78
|
62/78
|
|
Mean remifentanil consumption (μg)
|
2092 +/-1560
|
1829+/-1549
|
|
Intraoperative morphine (n° patients))
|
39/56
|
36/55
|
|
Mean intraoperative morphine (mg)
|
6±5
|
5.5±4.5
|
|
Epidural analgesia (n° patients) (started at skin closure)
|
6/78
|
7/78
|
|
Epidural analgesia failure (n° patients)
|
1/6
|
2/7
|
|
Intraoperative paracetamol (n° patients)
|
68/78
|
63/78
|
|
Intraoperative tramadol (n° patients)
|
69/78
|
62/78
|
|
Intraoperative nefopam (n° patients)
|
18/78
|
19/78
|
Table 3 PACU pain and sedation scores and analgesics
requirements.
|
Cases
|
Control
|
|
Pain scores median/(min-max)
|
|
|
|
Upon assessment
|
4
|
1.6 (1-2)
|
|
When leaving PACU
|
1.7 (1-2)
|
1.1 (1-2)
|
|
Sedation score median (min-max)
|
|
|
|
Upon arrival
|
1.1 (1-4)
|
1.2 (1-4)
|
|
When leaving PACU
|
1.2 (1-3)
|
1.2 (1-3)
|
|
Morphine requirements in PACU (mg)
|
13.2±6*
|
6.9±7
|
Discussion
This study shows that severe postoperative pain in the PACU has a
very low incidence (0.6%) in our institution thanks to systematic
anticipation. In addition, this retrospective case-controlled study
suggested that a significant independent factor to experience
severe postoperative pain despite routine anticipation was the use
of psychoactive medications in a chronic mode before surgery.
Several other factors are reported to be a significant predictor
of severe postoperative pain including chronic pain medication
[11], but also, gender, ASA status, alcohol dependence, type of
intraoperative opioid [12]. Psychoactive chronic treatment was
never reported to be a significant predictive factor of acute
postoperative pain in the PACU however reports exists suggesting
relation between anxiety and pain on postoperative day 2 [13] and
also further up to three months [14].
A recent systematic review suggest that main predictors of
postoperative pain are pre-existing pain followed by anxiety
while postoperative analgesic consumption depends mainly on the
type of surgery, age and psychological distress [8]. In another
study preoperative midazolam decreased postoperative anxiety and
opioid consumption in the first 24 hours [15] while another
investigation found a decrease in anxiety and postoperative nausea
and vomiting using mirtazapine [16].
Another recent retrospective study focused on a large cohort of
patients having different types of surgery in which uni and
multivariate analysis revealed multiple factors [4] in relation
with postoperative pain scores needing immediate intervention
(mainly above 4 in an 11 scale), these factors were
respectively younger age, female gender, obesity, use of nitrous
oxide, longer duration of surgery, location of surgery
(musculo-skeletal and intra-abdominal) and ASA status I-II.
Nevertheless our study concerned only cancer patients and was a
case controlled study concerning patients having very high scores
of postoperative pain.
In the present study sedation scores on arrival to PACU or upon
exit from the ICU were not different between the two groups however
our primary objective was to detect only the incidence of patients
with high pain scores, in addition contradictions exist between
sedation score and adequate analgesia [17, 18].
Aubrun et al. previously assessed the risk factor
predicting postoperative pain and found that preoperative
analgesics, general anesthesia procedures, and the amount of
intraoperative analgesics being a risk factor of high postoperative
pain scores [12], our study found different results probably
because of different population which was cancer surgery but also
the use of remifentanil in our institution which was not reported
in other studies. Psychological distress has also been reported to
be predictor of severe postoperative pain [8], we could not verify
this hypothesis but indirect putative assumption for patients
taking benzodiazepins and other psychotropes which were
significantly more important in the cases study group in comparison
to the controlled group could be in accordance with this study.
Although VAS remains the gold standard for the follow up of
postoperative pain, we used the numerical score since it was found
to be more preferred by nurses [19] in daily practice and to be
more reliable in the immediate period following anesthesia where
patient frequently presents accommodation difficulties.
A major shortcoming of this study is the retrospective nature of
it; however the large amount and almost exhaustive nature of the
patients in the database decrease selective recruitment bias.
Despite being an important predictor of postoperative pain [11]
preoperative pain scores were not assessed because of the design of
the study. The level of preoperative anxiety was not assessed
because of the same methological flaw but we believe the level of
anxiety is generally high in cancer patients [20].
In addition, our study confirms that high postoperative pain
scores were not encountered only in complex and long surgery, but
they were present in short and peripheral surgery [7] and in
laparoscopic surgery as previously reported [21] but also in breast
surgery which is known to yield moderate postoperative pain [22].
The proportion of patients with severe pain were probably lower
than other reported series mostly because of our systematic
anticipation of postoperative pain in a multimodal principle but
also the fact that some surgeries known to be painful as
orthopaedics are not performed in our institution. This study
suggest that the incidence of patients having very severe
postoperative pain in the PACU was very low (0.6%) albeit
anticipating treatment while cancer patients having anxiolytic
psychotropic treatment might be at more specific risk for severe
postoperative pain scores, therefore effort should be made for
prospective studies in the preoperative anaesthetic consultation to
identify such patients and try to develop an adequate strategy to
decrease severe postoperative pain [9].
Conflict of interest
none.
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