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Introduction:
Coronary heart disease is a life threatening condition for
human population. During surgical intervention like
Coronary Artery Bypass Graft (CABG), median sternotomy
is the best approach for a clear visualization of heart &
associated viscera. Median sternotomy is a type of surgical
procedure in which a midline vertical incision is made along
the sternum after which the sternum itself is divided or
cracked.1 Cardiac procedure requiring median sternotomy
includes coronary artery bypass grafting, valve
replacement, repair of a variety of congenital cardiac
diseases. Post-sternotomy pain is mostly musculoskeletal
& myofascial. These painful conditions are jointly called
post sternotomy pain syndrome2. Per-operatively it is
controlled by large bolus intravenous infusion of opioid
viz morphine or fentanyl. Thoracotomy, sternotomy and
the placement of pleural chest tubes results in considerable
pain in the post operative period in patients undergoing
CABG 3. Traditionally opioids and NSAID are used for
post operative pain management after sternotomy.

Postoperative Pain Management After Sternotomy In Off-Pump Coronary
Artery Bypass Graft (CABG) Surgery – A Comparative Study Between
NSAID (Diclofenac Sodium) and Opioid (Pethidine)
Kamrul Hasan1, Zerzina Rahman2, Ayesha Sultana1, Najib Ahsan3
1Consultant 2Associate Professor, 3Medical Officer, Dept. of Anesthesia, Analgesia & Intensive Care Medicine (Cardiac Anesthesia Wing),
BSMMU, Dhaka.

Abstract:
Background: Traditionally, postoperative pain has been managed either reactively with drugs given as needed or
proactively with continuous infusion of analgesics. Objectives:The present prospective comparative study was carried
out to find difference in efficacy between opioid and NSAID (Non-stroid anti-inflammatory drugs) in the post-sternotomy
pain management following off pump coronary bypass graft surgery. Methods: A total of 30 patients were randomly
divided into two groups. – 15 patients were treated with NSAID (Diclofenac sodium) and 15 patients with opioid
(pethidine) which are not commonly used in cardiac surgery. Patients ranging from 40 – 60 years with ASA Grade I & II
who underwent off-pump CABG with median sternotomy were included in the study.  Statistics: The test statistics used
to analyze the data were Chi-square Test and repeated measure ANOVA.  Result & conclusion: The study concluded
that the intensity of post-sternotomy pain was inappreciably higher in the NSAID group than that in the opioid group
throughout the whole period of observation suggesting that opioid (pethidine) would be a promising analgesic in the
post-sternotomy pain management than NSAID (diclofenac sodium) (p = 0.045).

Key words: Post-sternotomy pain: OPCAB: choice of analgesic.

[BSMMU J 2010; 3(2): 91-96]

Address for Correspondence: Dr. Zerzina Rahman, Associate
Professor; Department of Anesthesia, Analgesia & Intensive Care
Medicine (Cardiac Anesthesia wing); Bangabandhu Sheikh Mujib
Medical University, Dhaka, Bangladesh. E-mail:
bannya84@gmail.com

Inadequate analgesia causes respiratory, haemodynamic,
endocrine and metabolic complications. The preferred
drugs for postoperative pain management are opioids.
Pethidine is not a common opioid chosen for pain
management after cardiac surgery though it is used as a
common post-operative analgesic after general surgery.
Usually morphine is used for haemodynamic stability after
open heart surgery but it has a series of side-effects like
nausea, vomiting, constipation, respiratory depression.
NSAIDs are also used for analgesia. It also has some-side
effects such as gastro-intestinal disturbance, renal
impairment, decreased platelet function, impaired
coagulation etc4. In this study we assessed and compared
the efficacy of two different analgesics to relieve post
sternotomy pain with an assumption that opioid (Pethidine)
may have better effects than NSAID (Diclofenac Sodium)
in controlling the post-operative pain following sternotomy
for OPCAB (Off Pump Coronary artery bypass) surgery

Pain is more than just a physical process; it is a complex,
subjective phenomenon5. Pain can impair the haematologic,
immune, hormonal, cardiac, and respiratory systems.6 Pain
also can limit mobility7, interfere with sleep and rest, and
contribute to agitation, Psychosis, aggressive behavior,
and delirium8.



Surgical centers need to pay attention to pain management,
because there appears to be a direct relationship between
unrelieved pain and cost of medical care, time spent in an
intensive care unit, and length of hospital stay8.

Traditionally, postoperative pain has been managed either
reactively with drugs given as needed or proactively with
continuous infusion of analgesics 9. Evidence suggests
that reactive pain management is ineffective. With a
reactive approach, analgesics are administered at the
discretion of nurses and only on an as-needed basis.
Consequently, treatment takes place after pain occurs 10,
causing some patients to experience severe pain11. In
contrast, proactive pain management improves
effectiveness, because treatment is given before pain
occurs10. With a proactive approach, analgesics are often
administered via a continuous peripheral or epidural
infusion. However, because this approach may entail added
risk5, is short-term, high-tech, equipment dependent, and
often self-administered, it is neither available nor
appropriate for all surgical patients12.

Methods:
The present study was contemplated to compare the
efficacy between opioid and NSAID in the post-
sternotomy pain management following off-pump coronary
bypass graft surgery, to see the influence of analgesics
on haemodynamic state of the patients following off-pump
coronary artery bypass graft surgery, to find out
modulation of both early and delayed sequel of pain and
to observe the restoration of respiratory function.

The present study was a prospective study which was
carried out at Anesthesiology Department (cardiac
anesthesia wing) of Bangabandhu Sheikh Mujib Medical
University, Dhaka, over a period of 6 months from January
2009 to June 2009.

The study population was the patients scheduled for
elective cardiac surgery and underwent off pump CABG
with median sternotomy. Patients of ASA Grade I & II
between 40 – 60 years were included in the study. Patients,
who were not willing to participate in the study; had known
contraindication to opioid or NSAID, impaired kidney &
liver function and previous operation with median
sternotomy were excluded from the study. The
demographic variables studied were age, sex and BMI.
The safety variables were pulse rate, intra-arterial blood
pressure (systolic and diastolic), respiratory rate, SPO2
and the outcome variable was intensity of post-sternotomy
pain on visual analogue scale (VAS).

After selecting the patients based on selection criteria,
they were divided into two study groups using random
allocation procedure in Card lottery method. 30 patients
were divided into diclofenac (Gr. A) and opioid (Gr. B)group
– each containing 15 patients.

The patients of Group-A received diclofenac sodium 1 – 2
mg/kg body weight 12 hourly in intramuscular route up to
48 hours, while the patients of Group-B received pethidine
1.5 mg/kg body weight 6 hourly in the same route as
diclofenac sodium up to the same period. Observations
were made at 6 hourly intervals up to 48 hours and the
findings were compared between the groups to come to a
decision which group was better in terms of outcome
variable, postoperative intensity of pain.

Assessment of pain:

The uni-dimensional pain scales that can measure pain
intensity and are self reported by patients are numerical
rating scale, Verbal Rating Scale (VRS) and Visual Analogue
Scale (VAS). Visual Analogue Scale (VAS) involves asking
the patients to rate their pain from 0 – 10 (11 points) with
the understanding that 0 represents one end of pain
intensity continuum (no pain) and 10 represents the other
extreme of pain intensity (Unbearable pain). The strength
of VAS is its simplicity and therefore can be used with a
great variety of patients. Data were collected using a
structured questionnaire (research instrument) addressing
all the variables of interest.

Statistical analysis:

The test statistics used to analyze the data were descriptive
statistics, Chi-square (χ2) probability Test and repeated
measure ANOVA. The level of significance was set at 0.05
and p < 0.05 was considered significant.

Results:
A total of 30 patients scheduled for elective cardiac surgery
by off pump CABG with median sternotomy were planned
to be treated by NSAID (Group-A) and opioid (Group-B)
for postoperative pain management. Changes in pulse,
systolic and diastolic blood pressures, respiratory rate,
SPO2 and pain measured on VAS scale of the two groups
were compared at 6 hourly intervals after extubation.

Data analysis demonstrated that no significant difference
was found between groups with respect to Age and sex
distribution (p = 0.241).

The mean pulse rates of Group-A and Group-B were 108/
minute and 107/minute respectively at 6 hours of extubation
which decreased to 96/minute and 103/minute respectively
at 12 hours interval. Then both groups experienced a sharp

Postoperative Pain Management After Sternotomy In Off-Pump Coronary Artery Bypass Graft Kamrul Hasan et al

92



rise and sharp fall with decrease of pulse rates to 94 and
99/minute at 24 hours interval. Thereafter the variable
began to decrease insidiously and stabilized to 85 and 86/
minute in Group-A and Group-B respectively at the end of
48 hours. The changes in pulse rates were similar in both
groups  that means there is no significant difference (p =
0.836).

Fig..-1   depicts the changes in systolic blood pressure
(SBP) at different time interval. At 6 hours of extubation,
the mean SBPs of Group-A and Group-B were 149 and 132
mmHg respectively and continued decreasing up to 24
hours in Group-A and up to 30 hours in Group-B. Finally
the blood pressures stabilized to 115 and 113 mmHg in
Group-A and in Group-B respectively with no significant
difference between the groups (p = 0.171).

Visual Analog Scale (VAS):
The intensity of pain measured by visual analog scale
(VAS) shows that the mean pain score of Group-A and
Group-B were 6.9 and 6.8 respectively at 6 hours of
extubation which decreased insidiously to 4.1 and 3.3 at
48 hours. The intensity of pain was significantly higher in
the former group than that in the latter group throughout
the whole period of observation (p = 0.045) (Table VIII &
Fig. 7).

Table -I
Pain score in VAS scale at different time interval

Pain on VAS Group A Group B P-

(0-10 cm) at   n =15 n = 15 value

6 hours 6.9 ± 0.4 6.8±0.4 0.63 NS
12 hours 6.3 ±  0.4 6.1± 0.5 0.31 NS
18 hours 5.7± 0.5 5.9± 0.5 0.134 NS
24 hours 5.5± 0.6 5.3± 0.6 0.045 NS
30 hours 5.3± 0.9 4.7± 0.6 0.080 Ns
36 hours 4.9±0.7 4.5± 0.7 0.088 NS
42 hours 4.3 ± 0.8 3.5± 0.5 0.004 S
48 hours 4.1± 0.8 3.3 ± 0.4 0.004  S

# Repeated measure ANOVA statistics was employed to
analyze the data and ‘p’ refers to overall differences between
groups; S = Significant; NS = Not significant.

Fig.-1: Monitoring of SBP at different time interval

The mean diastolic blood pressure from 6 to 48 hours of
observation were significantly

higher in Group-A than those in Group-B (p = 0.021).
 (Fig.-2).

Fig.-2: Monitoring of Diastolic BP at different time
interval

Fig.-3 explains the changes of respiratory rate at different
time intervals. The rate was 19/minute in Group-A and 20/
minute in Group-B at 6 hours of extubation. Both groups
had some ups and downs and finally stabilized to 17/
minute in either group (p = 0.911).

Fig.-3. Monitoring of respiratory rate at different time
interval

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Discussion:
Adequacy of postoperative pain control is one of the most
important factors in determining when a patient can be
safely discharged from a surgical facility and has a major
influence on the patient’s ability to continue their normal
activities of daily living.15  Perioperative analgesia has
traditionally been provided by opioid analgesics viz
morphine, fentanyl etc. However, extensive use of opioids
is associated with a variety of perioperative side effects,
such as ventilatory depression, drowsiness and sedation,
postoperative nausea and vomiting (PONV), pruritus,
urinary retention, ileus, and constipation that can delay
hospital discharge14,17. Although these side-effects are
not encountered by the opioid group of patients in the
present study as the selection of postoperative opioid is
different here (pethidine) , we must keep in mind the
dangerous side effects of these drugs when planning for
postoperative analgesia in individual patients with opioid
group of drugs. Universally, the goal of peri-operative
pain management is to provide a good outcome of surgery.
The World Health Organization (WHO) has addressed
this goal by developing a framework for managing pain.
Accreditation standards have evolved and now include
specific expectations about the management of pain13.

Intra-operative use of large bolus doses or continuous
infusions of potent opioid analgesics may actually increase
postoperative pain as a result of their rapid elimination
and/or the development of acute tolerance16. In addition;
it has been suggested by the Joint Commission on
Accreditation of Healthcare Organizations that excessive
use of postoperative opioid analgesics leads to decreased
patient satisfaction. Partial opioid agonists (e.g., tramadol)
are also associated with increased side effects (e.g., nausea,
vomiting, ileus) and patient dissatisfaction compared with
both opioid 17 and non-opioid18 analgesics.

Some study reports earlier suggested that parenteral
NSAID possessed analgesic properties comparable to the
traditional opioid analgesics19 without producing any
opioid-related side effects20. Compared with the partial
opioid agonist tramadol, diclofenac produced better
postoperative pain relief with fewer side effects after
cardiac surgery21. When administered as an adjuvant
during outpatient anesthesia, diclofenac sodium was
associated with improved postoperative analgesia and
patient comfort compared with fentanyl and the partial
opioid agonist, dezocine22. Other investigators reported
that diclofenac sodium provided postoperative pain relief
similar to that of fentanyl but was associated with less
nausea and somnolence, as well as an earlier return of
bowel function23. In most studies, use of diclofenac

sodium has been associated with a less frequent incidence
of PONV than the opioid analgesics. As a result, patients
tolerate oral fluids and are fit for discharge earlier than
those receiving only opioid analgesics during the
perioperative period. Of interest, diclofenac sodium was
superior to a dilute local anesthetic infusion (bupivacaine
0.125%) in supplementing epidural PCA hydromorphone
in patients undergoing thoracotomy procedures24.
Furthermore, it has been found that the diclofenac sodium
at the incision site in combination with local anesthesia
resulted in significantly less postoperative pain, a better
quality of recovery, and earlier discharge compared with
local anesthesia alone24. In fact, there is evidence for both
a peripheral and central analgesic action of NSAID.25
However, when diclofenac sodium was substituted for or
combined with fentanyl during minor gynecologic and
laparoscopic procedures; the beneficial effects of the
NSAID were reduced26.

Despite the obvious benefits of using NSAIDs in the
perioperative period, controversy still exists regarding their
use because of the potential for gastrointestinal mucosal
damage and renal tubular and platelet dysfunction27.
Although some studies have found increased blood loss
and risk of reoperation when diclofenac sodium was
administered to children undergoing tonsillectomy
procedures28.

Opioid analgesics are a broad group of compounds that
includes naturally occurring extracts of opium, synthetic
surrogates, and endogenous peptides. Opioid receptors
are widely distributed, and close voltage-dependent
calcium channels, and opens calcium-dependent inwardly
rectifying potassium channels, resulting in inhibitory
effects characterized by neuronal hyperpolarization and
decreased excitability 29. Opioids are commonly
administered throughout the perioperative period for
cardiothoracic procedures. Intra-operatively, they are given
intravenously as either the primary anesthetic agent or,
more commonly, as an adjunct to a mixed anesthetic
technique that includes potent inhaled anesthetics,
benzodiazepines, and other agents. A primary benefit of
effective pain control is patient satisfaction. Outcome
benefits that involve peri-operative complications appear
to be highly related to the analgesia technique used,
particularly in relation to the effectiveness in blocking the
surgical stress response and nociceptive spinal reflexes.
Pavlin et al. confirmed that moderate-to-severe pain
prolonged recovery room stay by 40–80 min30. Use of
local anesthetics and NSAIDs decreased pain scores and
facilitated an earlier discharge home. Additional outcome

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94



studies are needed to validate the beneficial effect of these
non-opioid therapeutic approaches with respect to
important recovery variables (e.g., resumption of normal
activities, dietary intake, bowel function, return to work).
Although many factors other than pain must be controlled
to minimize postoperative morbidity and facilitate the
recovery process8. Pain remains a major concern of all
patients undergoing elective surgical procedures.

Opioid analgesics continue to play an important role in
the management of moderate-to-severe pain after surgical
procedures. However, adjunctive use of non-opioid
analgesics will likely assume a greater role as minimally
invasive (“key hole”) surgery continues to expand31. In
introducing new therapeutic  modalities for pain
management, it is important to carefully consider the risk:
benefit ratio32.  Use of local anesthetics and NSAIDs
decreased pain scores and facilitated an earlier discharge
home. In the present study, Diclofenac sodium and
Pethidine are compared to find a better option, because
pethidine is not a common choice for post-operative
analgesia in cardiac surgery. But the visual analogue scale
found the significance of difference in pain quality between
them.

The optimal non-opioid analgesic technique for
postoperative pain management would not only reduce
pain scores and enhance patient satisfaction but also
facilitate earlier mobilization and rehabilitation by reducing
pain-related complications after surgery. The visual analog
scale (VAS) has been used to assess the efficacy of pain
management regimens in patients with acute postoperative
pain. In this study, the intensity of pain measured on visual
analog scale (VAS 0 – 10 cm) demonstrated that the mean
pain intensity of Group-A and Group-B were 6.9 and 6.8
respectively at 6 hours of extubation which decreased
gradually to 4.1 and 3.3 at 48 hours. The intensity of pain
was significantly higher in the NSAID group than that in
the opioid (pethidine) group throughout the whole period
of observation (p = 0.045) indicating that use of Pethidine
in the post-sternotomy pain management is better and
faster than that of NSAID (diclofenac).previous pain
experience, anxiety, or anticipated pain with consistency
in VAS scores.

Conclusion:
From the findings of the study and discussion thereof it
could be concluded that the intensity of post-sternotomy
pain was significantly higher in the NSAID group than
that in the opioid group throughout the whole period of
observation suggesting that opioid (pethidine) though
uncommon in cardiac surgery, would be a promising

analgesic in the post-sternotomy pain management than
that of NSAID (diclofenac sodium).It again proves the
superiority of opioids as post-operative analgesics over
NSAIDs, though many studies elaborated in discussion
proved the efficiency and preference for it.

 However, our study findings are based on small sample
size which lacks generalization. Further study with large
sample is, therefore, needed to arrive at a definitive
conclusion. Moreover, the study did not consider the side-
effects encountered by the patients of two study groups.
Risk benefit ratio of the two study drugs must be weighed
before making a general recommendation as to which of
the two drugs should be used in the management of post-
sternotomy pain following off-pump CABG.

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