All data generated was checked and analysed using the Statistical Package for the
Social Sciences software (SPSS) version 21 for windows (IBM Corp, Armonk, NY, USA).The independent t- test was used to compare mean of continuous outcome variables like age, and pain scores between the treatment arms, while proportions of categorical variables between the groups were compared using the chi-square test. A p-value of <0.05 was considered significant in all the analysis. Information obtained from the study and findings from the data analysis was presented in
tabular forms.
CHAPTER FIVE RESULTS AND TABLES
TABLE 1: SOCIODEMOGRAPHIC FEATURES FOR PARTICIPANTS
Parameters Overall 1% Lidocaine Pentazocine
1. Age
Mean age 30.48 30.44 30.52
Standard Deviation 6.23 6.43 6.09
t-0.064, p=0.949
df-98,
2. Parity f (%) f (%) f (%)
0-2 36 (36) 20 (40) 16 (32)
3-5 46 (46) 21 (42) 25 (50)
6-8 16(16) 7 (14) 9 (18)
9-11 2 (2) 2 (4) 0 (0)
Total 100 (100) 50 (100) 50 (100) X2-6.373,
p=0.783
df-10,
3. Level of Educ ation
Primary 28 (28) 12 (24) 16 (32)
Secondary 56 (56) 30 (60) 26 (52)
Tertiary 16 (16) 8 (16) 8 (16)
Total 100 (100)
X2-0.2093, p=0.6473 50 (100) 50 (100)
EGA: The least gestational age was 10 weeks (4.4%), while the highest was 12 weeks (10%).
There was no statistically significant difference in the sociodermographic features among the participants in the two treatment groups.
ASSESSMENT OF PAIN SCORES BETWEEN STUDY TREATMENT GROUPS Results from the study revealed that majority (72%) of the participants managed with 1% Lidocaine for pain relief had pain scores within the range of 0 – <3, while majority (56%) of participants managed with intravenous pentazocine had pain score within the range of >3 – <6. There was a significant difference in the proportion of pain score range between the study treatment groups (χ2 = 12.005, p = 0.002). The mean pain score for participants managed with intravenous pentazocine was 4.44±1.82 and 1% Lidocaine was 2.91 (SD+1.84). Table 2 shows
the details of this finding.
Table 2: Comparison of Proportion of Pain Score Range between the Treatment Groups
Analgesics Range of Pain Scores
0 - ≤3 >3 - ≤6 >6 -10 (Mild) (Moderate) (Severe)
Overall Total
(f)
Chisquare (χ2)
p-value
1%
Lignocaine
36
13 1
50
Pentazocine 19 28 3 50 12.005 0.002
Total 55 41 4 100
COMPARISON OF SIDE EFFECT PROFILE FOR PENTAZOCINE AND 1%
LIDOCAINE WHEN THEY WERE USED FOR PAIN RELIEF DURING MANUAL VACUUM ASPIRATION
Table 3 shows the side effect profile for Pentazocine and 1% Lidocaine when used for pain relief during manual vacuum aspiration for all the participants in the treatment groups (N = 100). Overall, the table revealed that those in the pentazocine group had more side effects compared to those who had 1% Lidocaine and this was statistically
significant for headache (χ2 = 13.255, p = 0.0005), dizziness (χ2 = 33.653, p = 0.0005), Nausea (χ2 = 9.013, p = 0.003), vomiting (χ2 = 11.960, p = 0.001), weakness (χ2 = 50.174, p = 0.0005), blurred vision (χ2 = 6.658, p = 0.010), and double vision (χ2 = 4.252, p = 0.039). There was however no significant difference for confusion (χ2 = 2.819, p = 0.093), and tremor (χ2 = 1.396, p = 0.237). The details of these findings are shown in table 3.
Table 3a: Comparison of Side Effect Profile for Pentazocine and 1%
Lidocaine When Used For Pain Relief During Manual Vacuum Aspiration
Analgesics Side effects Chi-square
(χ2) p-value
Headache
No Yes
1% Lignocaine 49 1
Pentazocine 36 14 13.255 0.0005
Total 85 15
Dizziness
No Yes
1% Lignocaine 40 10
Pentazocine 11 39 33.653 0.0005
Total 51 49
Confusion
No Yes
1% Lignocaine 50 0
Pentazocine 48 2 2.813 .093
Total 98 2
Nausea
No Yes
1% Lignocaine 44 6
Pentazocine 31 19 9.013 0.003
Total 75 25
Vomiting
No Yes
1% Lignocaine 49 1
Pentazocine 37 13 11.960 0.001
Total 86 14
Seizure
No Yes
1% Lignocaine 50 0
Pentazocine 50 0
Total 100 0
Weakness
No Yes
1% Lignocaine 49 1
Pentazocine 15 35 50.174 0.0005
Total 64 36
Facial oede ma
No Yes
1% Lignocaine 50 0
Pentazocine 50 0
Total 100 0
Table 3b: Comparison of Side Effect Profile for Pentazocine and 1%
Lidocaine When Used For Pain Relief During Manual Vacuum Aspiration
Analgesics Side effects Chi-square (χ2)
p-value
Tremor
No Yes
1% Lignocaine 49 1
Pentazocine 50 0 1.396 0.237
Total 99 1
Blurred vision
No Yes
1% Lignocaine 50 0
Pentazocine 42 8 6.658 0.010
Total 92 8
Fever
No Yes
1% Lignocaine 50 0
Pentazocine 50 0
Total 100 0
Double vision
No Yes
1% Lignocaine 50 0
Pentazocine 47 3 4.252 0.039
Total 97 3
COMPARING EFFECTIVENESS OF BOTH AGENTS FOR PAIN RELIEF THROUGH ANALYSIS OF MEAN PAIN SCORES (Testing the hypothesis)
The hypothesis was tested with the independent t-test and results revealed that overall, mean pain score for the study participants (N 100) was 3.68 with a standard deviation of 1.98. There was a statistically significant difference in mean pain score between the treatment groups with participants that were administered 1% Lidocaine experiencing less pain than those administered pentazocine (t = 4.166, df = 98, p = 0.0005). Table 4 shows the details of the result.
Table 4: Independent t-test for Pain Scores across the Treatment Groups
Study group Mean Pain Standard t df p-value score deviation
1% Lidocaine 2.91 1.85
4.166 98 0.0005
Pentazocine 4.44 1.82 CHAPTER SIX DISCUSSION
Pain management remains a major aspect of care given to patients who undergo manual vacuum aspiration for incomplete abortion and therefore analysis to asses an effective method of this care is essential in ensuring a good outcome after the procedure.
This study was a randomized controlled trial that set out to compare the effectiveness of pain management between pentazocine and paracervical block during manual vacuum aspiration using a visual analogue scale and also to compare the side effect
profile between these two agents. This is to determine which of them will be more effective with fewer side effects.
From the outcome of the study, when pentazocine was used as the form of analgesia, majority of the participants (56%) had a pain score within the range of >3 to <6 (moderate pain) and a mean pain score of 4.4 (SD+1.82). This outcome probably could have been as a result of the systemic administration and a larger volume of distribution resulting in a reduced bioavailability at the site of the procedure where the action of pentazocine is needed. This value is less than the mean pain score of 5.68 (SD+2.58) as obtained in a study done in Kano when single agent pentazocine was compared with a combination of Pentazocine and diclofenac2 which may have been as a result of sociodermographic and geographical variation.It was concluded from that study that use of pentazocine is effective in pain management especially when used in conjunction with other forms of analgesia such as diclofenac2. The use of pentazocine is a predominant form of analgesia because of its satisfactory pain management as shown in studies done in places like Maiduguri 5, Nguru68 and Jos6, Nigeria; even though pain assessment was not done objectively using a scoring system in these studies. The pain score obtained in this study is therefore comparable to the outcome in these areas as pentazocine was equally reported effective. A randomized controlled trial comparing different methods of analgesia used in abortion during manual vacuum aspiration showed a mean pain score of 5.7 when opiate analgesia was used34. This is significantly more than the mean pain score for pentazocine (4.4) obtained in this study even though they are both within the range for moderate pain following assessment. It could probably be that even though they both belong to the
same class of drug (opiate analgesic), meperidine which was the actual opiate used in that study has a low bioavailabity of 50-60%10, 43for action at the site of the procedure compared to that of pentazocine (60-70%) 39which is a result of the difference in the protein bound proportion of these drug in the blood stream. It is no wonder the mean pain score of pentazocine is lower as obtained in this study.
Among the participants in the Paracervical block arm, majority (72%) of them had a pain score in the range for mild pain (0-< 3)with an overall mean pain score of 2.91 (SD+1.85).This also places the mean pain score for this group within the range for mild pain sensation (<3). This could be explained by the local administration of 1%
lidocaine at the site of the procedure making the bioavailability higher. The adrenaline in this preparation which causes vasoconstriction further prevents the drug from significant systemic absorption which in essence maintains the drug at the site of the procedure. This value is comparable with the mean pain score of 2.78 in a study done in Hong Kong to assess the effectiveness of paracervical block for pain management during manual vacuum aspiration 69.It has also been shown in a Cochrane review that evidence supporting a significant reduction in pain sensation during cervical dilatation and uterine evacuation does exist and this further buttresses the finding obtained from this study14. Another Cochrane review of anesthesia for evacuation of incomplete abortion have also shown that women under paracervical block with lidocaine present less commonly with moderate or severe pain13 which further buttress the findings from this study (a range of 0-<3 and mean pain score of 2.91 being in the mild range).A Placebo-controlled clinical trial done in Turkey, showed that PCB with Lidocaine gave a mean pain score of 6.56 + 1.4370. This difference compared to that obtained in this
study may have been as a result of the variation in the sociodermographic factors such as cultural beliefs that may influence pain perception among women in Nigeria compared to those inTurkey. Another study done in Nairobi, Kenya compared 1%
lidocaine with placebo and pain was assessed using McGills and facial expression16. Those who had lidocaine had significantly less pain than those in the placebo group as those in the latter group complained of lower abdominal pain and backache more than the former group. These pains were significantly more during the procedure than 30minutes after16. It was recommended at the end of the study that all patients having manual vacuum aspiration should have paracervical block with lidocaine as it was found to be effective for pain management16. This finding further supports the low mean pain score of 2.91 using paracervical block obtained in this study.
In comparing the range of pain scores for the two methods of pain relief during manual vacuum aspiration in this study, majority (72%) of the participants in the paracervical block group were in the mild pain range (0- <3) while majority (56%) of those in the pentazocine arm were in the moderate pain range (>3 - <6). As the pain score range increased from mild to severe, fewer participants experienced more pain in the paracervical block group while this was not the case in the pentazocine arm. There was a statistically significant difference (p value=0.002) between the two groups with those in the paracervical block group experiencing less pain compared to participants in the pentazocine group. When paracervical block is properly administered, it gives an excellent anesthesia without somatic or motor block 13, 15, 16. This difference may have been because paracervical block with lidocaine is thought to block pain
conduction via Frankenhauser’s plexus, which causes an infiltrative effect that prevents generation/conduction of nerve impulses by reducing sodium permeability and increasing action potential threshold. This in turn inhibits depolarization, which results in blockade of conduction causing loss of pain sensation around the area supplied by the nerve thereby decreasing pain associated with
dilatation10, 14, 15, 43. This is a local action that takes place at the site of the procedure as opposed to administration of intravenous pentazocine which acts centrally on the kepper and miu receptors to abolish pain39. Again, the volume of distribution for intravenous pentazocine is larger as it is given directly into the blood stream15. This may suggestless concentration of this drug at the site of the procedure ultimately reducing the bioavailability. The adrenaline in the 1% Lidocaine used for paracervical block further enhances the local action by aiding vasoconstriction keeping this drug at the site of the procedure which may further potentiate the analgesic effect14, 15. A comparative study done for pregnancy termination compared pain relief between paracervical block and pentazocine and it showed that during evacuation, using either manual vacuum aspiration or electric vacuum, intra and post-operative pain was significantly less when paracervical block was used making it a more effective method for pain relief71. This finding is in keeping with the outcome obtained in this study.
The recommendation by the World Health Organization and the Royal College of Obstetrician and Gynaecologist is that local anaesthesia and intravenous analgesia have been shown to decreased procedural pain, while being safe and satisfactory to patients during uterine evacuation 2, 12. However,from the findings in this study, it is
obvious that paracervical block with 1% lidocaine is a more effective analgesic for pain relief during manual vacuum aspiration when compared to intravenous
pentazocine with a statistically significant difference in the range of pain scores.
Majority of the participants in the pentazocine group had side effects to the drug with 78% and 70% experiencing dizziness and weakness respectively. Nausea was a side effect in 38% of the participants in this group while Headache and vomiting had similar proportions (28% and 26%). Blurred vision (16%), double vision (6%) and confusion (4%) were present in a few of the participants.This may have been due to systemic distribution of the drug with a central nervous system action resulting in a multisystem involvement in the mechanism of action. None of the participants in this arm had fever, tremor, facial oedema or seizure. In the study done in Kano, the side effects of pentazocine that were commonly reported were nausea, vomiting and dizziness which is a similar finding obtained in this study 2. However, when pentazocine is used in combination with diclofenac, the side effect was less in that study 2. Therefore pentazocine should not be used alone as a sole form of analgesic for pain relief during manual vacuum aspiration.
From the study, less than half of the participants in the paracervical block arm had side effect. Dizziness was found in 20% of the participants and 12% had nausea.
While headache, vomiting and tremor each all occurred in 2% of the participants, none of the participants in this group had double vision, fever, blurred vision, facial
oedema, seizure or confusion. This may have been as a result of the locally administered 1%lidocaine for paracervical block which acted more at the site of the
surgery.The fewer side effect found in this study is in keeping with the finding by the WHO and RCOG which resulted in the recommendation for its use for pain relief during manual vacuum aspiration 12. When properly administered, paracervical block has been shown to avoid systemic side effect that other intravenous or intramuscular anaesthesia may cause 13, 15, 16and thismay explain the fewer side effect obtained in this study.
There was a statistically significant difference when headache (p=0.005), dizziness (p=0.005), nausea (p=0.03), vomiting (p=0.001), weakness (p=0.005), blurred vision (p=0.01) and double vision (p=0.039) were compared between the two groups with those in the pentazocine arm experiencing more of these side effects than the participants in the paracervical block group. This again may be explained by the parenteral administration of pentazocine which may ultimately give more systemic side effect than locally administered paracervical block which has more action at the site where it was given.
There was no statistically significant difference in confusion and tremor between the two groups and neither of the groups had seizure, facial oedema or fever.
Testing the hypothesis
When the hypothesis was tested using the independent t-test, there was a
statistically significant difference (p=0.0005) in the mean pain score. This means that participants who were administered 1% lidocaine experienced less pain compared to those in the pentazocine. The findings from this study is in keeping with studies by Egziabher et al and Calcavhe et al which also found a lower mean pain score when
lidocaine was used for paracervical block 13, 16. From the foregoing, the null hypothesis therefore is rejected.