ABASTRACT
Objective: The aim of this
study is to explore the effect of supplemental pre-operative fluids on the
incidence of nausea and vomiting that occur post-operatively.
Methods: We studied sixty
patients, ASA I-II, undergoing laparoscopic cholecystectomy. Patients were randomly divided into groups A
and B; group A (n=30 patients) received no intravenous fluids pre-operatively,
whereas group B (n=30 patients) received supplemental fluids (10ml/kg of lactated Ringer's solution) one hour before induction of
anaesthesia.
Results: During the first
twenty four hours post-operatively, nausea and vomiting occurred in 21 patients
(70%) ofrom group A and only in 8 patients (27%) from group B (supplemental
fluid group).
Conclusion: Post-operative nausea and vomiting
can be reduced by the use of pre-operative supplemental lactated Ringer’s
solution, which is a cheap and safe therapy.
Key words: Fluid therapy, Hypovolemia,
Post-operative nausea, Vomiting
JRMS
December 2009; 16(3): 31-35
Introduction
Today, the incidence of
postoperative nausea and vomiting (PONV) still appears to be about 38%,(1,2)
before the 1960s, when older inhalational anaesthetic agents were widely used,
the incidence of PONV was as high as 60%.(3) Despite better anaesthetic
techniques along with new generation of anti-emetics and shorter acting
anaesthetic drugs the rate was only reduced to 30%,(3) and
still it reaches up to 79% in high risk patients.(1,2) The
benefit of routine prophylactic anti-emetic treatment has been questioned
because anti-emetics may have side effects.(1) Even mild PONV can delay hospital
discharge (in fact it is the leading cause of unexpected admission following
planned day case surgery),(4) decrease patients’ satisfaction
and increase use of resources.(5) Avoiding
PONV is important to patients, more so than avoiding postoperative pain.(6)
It has been suggested that good oxygenation
of patients postoperatively reduces the incidence of nausea and vomiting
preventing the subtle intestinal ischemia caused by surgery or anaesthesia.(4,7-10) However, if the
patient is in low perfusion state, oxygen alone may not be beneficial.(9)
Fasting for long periods and bowel preparations without adequate preoperative
fluid replacement for surgical patients make them hypovolemic and more prone to
postoperative nausea and vomiting.(9)
We performed a prospective, randomized, double blinded study to test
the hypothesis of supplemental administration of fluid (lactated Ringer's
solution) preoperatively will decrease the incidence of post-operative nausea
and vomiting in patients who undergo laparoscopic cholecystectomy.
Lactated Ringer's solution (Hartmann’s) is an isotonic intravenous
solution, Oone liter of Llactated Ringer's solution contains:
·
130mEq
of sodium ion.
·
109mEq
of chloride ion.
·
28mEq
of lactate.
·
4mEq
of potassium ion.
·
3mEq
of calcium ion.
Methods
We studied 60 patients who underwent laparoscopic cholecystectomy at Princess Haya Al-Hussein
Hospital inAqaba between
August 2003 and May 2004. All patients were ASA I-II, were aged 20-81 years and
had no previous cardiovascular, hepatic, renal, gastrointestinal or
neurological disorders. Patients were asked to fast for 6-8 hours and were
operated upon first on the list. Patients
who experienced nausea or vomiting on the morning of operation were excluded as
well as patients who were delayed till the afternoon for any reason; also
patients who already were on anti-emetic drugs were excluded.
Patients were prospectively and randomly divided into two groups: group
A patients received no preoperative intravenous fluid supplement, and group B
patients were given preoperative intravenous supplemental fluid therapy of lactated Ringer's solution 10ml/kg of body weight. Randomization was performed by the nurse in
the pre-operative holding area who picked one of a prearranged and sealed sixty
similar envelopes, thirty of which contained the word ‘conservative’ and the rest contained
the sentence ‘IV lactated Ringer's solution’.
The fluid was administered in the pre-operative holding area before
induction of anesthesia.
The patient, the anesthesia provider, the post-operative study
investigator and the nurses in recovery area and on the wards were unaware of
the patient’s group.
A standard anesthetic technique was followed for all patients who
included the administration of Midazolam 2mg intravenously followed by Propofol
3mg/kg, fentanyl 1-3mcg/kg, and atracurium 0.5mg/kg. An endotracheal tube was placed and
anaesthesia was maintained with sevoflurane 1-2% in 70% nitrous oxide and
oxygen. End tidal CO2 was
maintained around 35-40 and SpO2 above 95%. Nasogastric tube was also inserted for all
patients and maintained on low suction throughout the procedure, and removed
just before the end of anesthesia. Intraoperative
fluid requirements were standardized for all patients (5ml/kg/hour of lactated
Ringer's solution).
Monitoring of all patients was also standardized and included ECG, SpO2,
heart rate, blood pressure, capnography, tidal and minute volumes, and end-expiratory
concentration of inhaled anaesthetic.
Incremental doses of analgesics, fentanyl 50-100mcg, or morphine 1-2mg
were given according to clinical signs. Reversal
of neuromuscular blockade was achieved at the end of operation using
neostigmine 2.5mg and atropine 1mg.
All patients received 100% oxygen during recovery time, and were given
post-operative analgesics as needed during their stay in the recovery room
which was around one hour. They were then sent to the ward. No patient was
discharged home the same day.
Patients were asked to rate their nausea on a 100mm visual analogue
scale (VAS) at 15 minute intervals
throughout recovery where 0 equalled no nausea and 100 was the worst imaginable
nausea. A score of 50mm or above was
considered significant.
Patients were followed up by the investigator to record severity of
nausea and occurrence of vomiting after leaving the recovery room till the end
of the first 24 hours post-operatively.
Chi-square test was used to examine for the
presence of significant differences between the two groups in regard to the
rate of nausea and vomiting they experienced protoperatively. Chi-square test was
also used to test the difference in the rate of PONV history and smoking
between the two groups. The t-test was used to investigate the difference between the two
groups for age and weight factors. A
probability value of <0.05 was considered statistically significant. Statistical analysis was carried out on SPSS software version 11.
Table I. characteristic
of patients in groups A and B
|
|
Group A
n=30
|
Group B
n=30
|
P Value
|
|
Age range
(mean)
|
22-79(48)
|
20-81(46)
|
0.36
|
|
Weight
range kg (mean)
|
50-85(70)
|
49-88(73)
|
0.09
|
|
Female:
Male ratio
|
22:8
|
24:6
|
|
|
History
of PONV (%)
|
7(23%)
|
6(20%)
|
0.754
|
|
Smoking
(%)
|
6(20%)
|
8(26%)
|
0.542
|
Table II. Duration of anaesthesia and intravenous fluids
and drugs given to patients randomly assigned to groups A and B.
|
|
Group A
|
Group B
|
|
Duration of anaesthesia; minutes range(mean)
|
60-150(102)
|
45-140(90)
|
|
Intravenous fluids:
Preoperative; ml range(mean)
Intraoperative; ml range(mean)
|
|
|
|
0
|
490-880(738)
|
|
325-1025(590)
|
260-885(551)
|
|
Propofol; mg range(mean)
|
150-255(210)
|
147-264(221)
|
|
Intraoperative analgesics:
Fentanyl; mcg range(mean)
Morphine; mcg range(mean)
|
|
|
|
150-270(212)
|
150-260(217)
|
|
0-12(7.5)
|
0-10(6.75)
|
|
Postoperative analgesic (0-1 hour):
Fentanyl; mcg range(mean)
Morphine; mg range(mean)
|
|
|
|
0-100(54)
|
0-100(45)
|
|
0-10(5.25)
|
0-10(5.0)
|
|
Postoperative analgesic (1-24 hour)
Morphine; mg range(mean)
|
|
|
|
0-15(9.5)
|
5-20(12.75)
|
Table III. Incidence of post-operative
nausea and vomiting in groups A and B (A: no fluid supplement pre-operatively,
B: supplemental fluid pre-operatively).
|
|
Group A
n=30
|
Group B
n=30
|
p-value
|
|
0-1 hour post-operatively:
Nausea n (%)
Vomiting n (%)
|
12(40)
4 (13)
|
4 (13)
2(7)
|
0.02
0.09
|
|
1-24 h post-operatively:
Nausea n (%)
Vomiting n (%)
|
17(57)
5 (17)
|
6(20)
2 (7)
|
0.004
0.212
|
|
0-24 h postoperatively:
Nausea n (%)
Vomiting n (%)
|
21(70)
9 (30)
|
8(27)
3 (10)
|
0.000
0.052
|
Results
Patients' characteristics are shown in Table
I. Duration of anesthesia and use of
intra-operative intravenous fluids and drugs were almost similar in the two
groups (Table II). The incidence of
nausea and vomiting is shown in Table III.
The incidence of nausea was higher in group A (conservative) in both
categories the 0-1 and 1-24 hours compared to group B (12 vs. 4 P=0.02
and 17 vs. 6 P=0.004 respectively), and was more significant over the
whole 24 hours (21 vs. 8 P=0.000).
Though the frequency of vomiting was higher in the conservative group
(A) 0-1 hr, 1-24 hrs and 0-24 hrs (4 vs. 2 P=0.09, 5 vs. 2 P=0.212
and 9 vs. 3 P=0.052 respectively) but the difference was not significant
in any category.
Discussion
Many controversial articles
have been published over the influence of perioperative fluids on PONV, where
some papers supported their effect with significant decrease in PONV.(11-14)
Other studies were unable to show a significant difference in the early
post-operative period, though some have showed a significant difference only
three days postoperatively.(15-18) Apart from very few
studies,(14,17) in all the other performed studies,
supplemental fluid was administered intra-operatively.
Yogendran et al.,
who administered fluids before induction of anaesthesia, was unable to show a
significant difference in the early post-operative period but also reported a
decreased incidence of late post-operative nausea. (18) As in previous studies,(14)
we saw a significant reduction in the incidence of post-operative nausea and
vomiting as well as in the VAS
scores during the 24 hours following anaesthesia.
In our study, although we used
only 10ml/kg of preoperative fluid supplement and still we were able to
identify a significant decrease in the rate of nausea within the first 24 hours
from 57% to 20% (1-24hr, P=0.004) and from 70% to 27% (0-24hrs, P=0.000). There was also a significant difference in
the incidence of nausea up to one hour from 40% to 13% (P=0.02), but this
observation was not significant in the previous studies. As for vomiting,
though there was a drop in the rate of vomiting in all categories (0-1 hour 13%
to 7% P=0.09, 1-24 hours 17% to 7% P=0.212, and in 0-24 hours 30%
to 10% P=0.052), the drop was not significant.
Another noticeable observation
in our study was that while the other studies were mainly of minor outpatient
procedures, our study was on patients undergoing laparoscopic cholecystectomy,
and were at higher risk of postoperative nausea and vomiting because they all
underwent the procedure under general anesthesia, were mainly females,
non-smokers and received postoperative opioids. These four factors themselves
have been confirmed by Apfel and Stadler to be significant risk factors for
postoperative nausea and vomiting.(2,19)
Many theories have been
proposed to explain how fluid therapy reduces nausea, one theory suggested that
perioperative hypo-perfusion of the gut mucosa and consequent ischemia might be
one of the causes of post-operative nausea and vomiting.(18) Gut ischemia is common during
anaesthesia and surgery, and results in release of serotonin, which is one of
the most potent triggers of nausea and vomiting.(18)
Mythen and Webb showed that
perioperative plasma volume expansion reduced the incidence of abnormal
intramucosal pH in patients having elective cardiac surgery, and was associated
with improved outcome.(10) It was also found that administration of
additional oxygen decreases the incidence of post-operative nausea and vomiting.(7,8)
However, even supplemental oxygen
fails to increase tissue oxygenation during hypovolaemia.(7,8)
Most of our patients become
hypovolaemic before induction of anaesthesia due to overnight fasting,
especially in those with bowel preparation. Euvolaemia is often not
re-established until the post-operative period. Supplemental fluid load before
start of anaesthesia most likely decreases the volume deficit, thereby
promoting euvolaemia. A positive effect on splanchnic perfusion might
inhibit the impending intestinal ischemia.(20)
In conclusion, post-operative
nausea and vomiting can be reduced by the use of pre-operative supplemental lactated
Ringer’s solution, which is a cheap and safe therapy.
References
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TJ. Postoperative nausea and voimiting- Can it be eliminated? . JAMA 2002;
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