4. Discussion
Procedural pain occurs when the integrity of the skin or tissue is damaged by diagnostic or therapeutic manipulations [
3]. Most common in the neonatal period are venipuncture, muscle injections, endotracheal intubation, eye examination, lumbar puncture, blood collection from the heel and others. Prevention and treatment of pain in neonates is important because exposure to repeated painful stimuli early in life has immediate short-term and long-term adverse effects, including irritability, disturbed sleep-wake state, ventilation-perfusion mismatch, increased oxygen consumption and impaired nutritional intake [
4,
5].
Numerous studies have documented neonatal responses to pain, which include autonomic (eg, increases in heart rate, blood pressure), hormonal (eg, cortisol and catecholamine responses), and behavioral changes (eg, facial grimace). These responses form the basis of the many pain assessment tools used to evaluate acute pain in the neonate. Physiologic parameters include changes in heart rate, respiratory rate, blood pressure, vagal tone, heart rate variability, breathing pattern, oxygen saturation, intracranial pressure, palmar sweating, skin color, or pupillary size. Behavioral responses include crying patterns, acoustic features of infant crying, facial expressions, hand and body movements, muscle tone, sleep patterns, behavioral state changes, and consolability [
6].
According to the international consensus for the assessment of neonatal pain, two of the most frequently applied scales in term and preterm newborns are: Neonatal Infant Pain Scale (NIPS) and Neonatal Facial Coding System (NFCS). The multimodal NIPS is used to assess pain in preterm and term neonates [
7]. It includes one physiological /breathing patterns / and five behavioural reactions: facial expression; cry; arms; legs; and state of arousal [
7,
8]. Items are rated 0 or 1. Only the crying factor is rated 0,1 or 2. The sum of the items is referred to as an evaluation score and gives a quantitative assessment of the presence and severity of pain. The inventors of the scale and other authors accept the presence of pain at a score ≥ 4 [
9,
10]. Independently, the minimum score is 0 points, and the maximum is 7 points.
The unimodal NFCS was created in 1987 by Grunau et al. and has later undergone various modifications [
11]. Mimic changes for pain assessment in full-term and premature newborns in the original scale are as follows: 1. Brow bulge; 2. Eyes squeeze; 3. Nasolabial furrow; 4. Open lips; 5.Taut tongue; 6.Tongue sticking out; 7.Chin quiver; 8. Stretched mouth: 8.1 Horizontal mouth, 8.2 Vertical mouth, 8.3 Oo-shaped mouth.
11 The evaluation is rated 0 or 1 according to the presence or absence of the corresponding indicator. When using the NFCS an optimal score of 8 is accepted, and pain is reported at ≥ 3 [
12,
13].
Based on literature data, we accepted the following: absent pain when score is less than 4 ac-cording to NIPS or less than 3 according to NFCS; pain when NIPS score was ≥ 4; NFCS score was ≥3, and very severe pain - when score is above 6 in NIPS and above 7 in NFCS , with a maximum score 7 in the NIPS, and 8 in the NFCS [
8,
13,
14,
15].
Over the past two decades, analgesia with sweet solution has been extensively studied in neonates undergoing painful procedures. Sweet taste is thought to trigger the release of endogenous opioids. The analgesic effectiveness of the solution may depend on its degree of sweetness, arranged in the following order according to the degree of manifestation: sucrose, fructose, glucose and lactose [
16]. Many studies have shown that oral sucrose is safe and effective in reducing nociception in single and short-term procedures, and as a result it has been proposed as the standard of treatment on procedural pain [
17]. Analgesic effect of sweet solution is controversial when applied to several consecutive painful procedures [
18]. It has been suggested that the greatest analgesic effect is achieved when the sweet solution is given approximately two minutes before the start of the painful procedure. According to one hypothesis, this interval coincides with the endogenous release of opioids, but the mechanism of its analgesic action is still incompletely understood and partly controversial [
19].
Recent systematic reviews have shown that sweet taste is effective in reducing behavioral indicators of pain in infants up to 1 year of age during common minor procedures such as venipuncture, bladder catheterization, circumcision, subcutaneous, intramuscular injections, ophthalmoscopy, placement of nasogastric tube, and heel prick tests [
20,
21]. As the most common painful procedure, heel prick tests were investigated in 38 studies [
21]. In some of them, with glucose intake, different scales were used to evaluate the behavioral markers-NIPS [
22,
23], PIPP[
23,
24], DAN[
25], NFCS [
26,
27] and was also reported the dynamics on the physiological indicators of pain [
27,
28,
29]. Most of the studies prove the analgesic effect of sweet solutions, but some of them do not register it for procedural pain [
21,
23,
30]. Akcam M.[
31] reported no difference in control of procedural pain between glucose and fructose, and data comparing the analgesic effects of sucrose and glucose were variable [
21]. Guala A et al.[
29] and Isik U et al. [
32] found during heel prick tests no significant difference between the two carbohydrates in changes to heart rate, but the second cohort recorded a shorter crying time with sucrose compared to glucose. Suhrabi et al. [
33] register no difference in NIPS score at 1
st and 2
nd min after immunization, which was also confirmed by Kumari S.[
34] in a double-blind randomized controlled trial, where 25% glucose and 24% sucrose were comparable as analgesia for pain relief during heel prick. Therefore 25% glucose solution can be used as an alternative to sucrose to reduce procedural pain in healthy term and preterm neonates. There is evidence that sucrose and glucose (20% to 50%) significantly reduce NIPS values in the heel prick [
21,
22,
34,
35].
Comparing the glucose group with the NIPS control group in the present study found that the anesthetised patients had a significantly lower score compared to the 5
th min control group (p=0.000). That is a reduction in pain intensity and duration after administration of 25% glucose solution, which confirms the analgesic effect of glucose in procedural pain caused by a heel prick test. A lower NIPS score was recorded with the administration of 25% glucose solution, both after venipuncture [
36] and with intramuscular injections [
33].
According to the literature data, facial manifestations of procedural pain were detected in 99% of newborns within 6 seconds after a heel prick test, and are thought to be very sensitive indicators of infant pain [
37]. Using the NFCS pain rating scale, Ogawa et al. [
26] and Okan F et al.[
27] found a significantly lower pain severity when applying sweet solutions after procedural pain, such as a heel prick test. Gaspardo et al. [
38] assessed newborns' facial activity by NFCS, using the behavioral marker of cry, and the physiological marker of heart rate, after administration of sweet solutions in venipuncture, and also proved their analgesic effect. According to our results, the overall NFCS score there are a tendency towards a lower score at the 5
th minute, below 3 (2.95), which is minimal for pain (p=0,006).
In their study, Asmerom et al. [
39] reported that a single dose of sucrose reduced behavioral indicators of pain by heel prick tests in preterm infants, but increased the physiological markers of oxidative stress and heart rate. These results coincide with ours: the application of Sol. Glucose 25% recorded the highest values of heart rate at the 30
th second, as well as lower oxygen saturation and slower breathing even before the procedural pain. These statistically significant pre-screening differences in respiratory rate, oxygen saturation, and systolic and diastolic blood pressure, are assumed to be the result of the action of the applied oral intake of Sol.Glucose 25% associated with intracellular oxidative stress as well as sympathetic activation [
16]. Published studies also found increases in heart rate, decreases in oxygen saturation, and lower respiratory rates, but without statistically significant results [
40,
41].
In the present study, at the 30
th second the higher heart rate in the anesthetised newborns is striking (p=0.012), which is probably related to the described supposed influence of the sweet solution [
21]. At the 5
th minute after the procedure, we report significant differences in the values of the indicators: respiratory rate lower (p=0.007) and systolic pressure higher (p=0.000), which we associate with the continued effect of the glucose solution. Our results match with those of Liaw JJ et al. [
42], where after application of Hbvax under anesthesia with glucose solution were reported a higher value of heart rate and a decrease in respiratory rate, as well as their significant stabilization. Jatana SK et al. [
28] also reported a significant increase in heart rate, and a decrease in crying time and oxygen saturation under glucose analgesia following blood collection from the heel.
In the interval 12-24 hours we found no deviations from the norm for the age of the monitored physiological indicators - heart rate, respiratory rate, transcutaneous saturation and arterial pressure after analgesia with Sol.Glucosae 25% .
Homeopathic agents can be used for certain conditions in the neonatologist's clinical practice [
43,
44,
45]. The use of homeopathic agents with Arnica in newborns after traumatic births or other injuries (venipuncture) is appropriate because it improves the physical and mental recovery of the body. In connection with these effects, the intake of Arnica as well as Staphysagria and Calendula is recommended to boys post circumcision [
46].The use of Arnica before and after surgery to reduce hematoma, swelling, tenderness, and pain has been documented. The effect is associated with variations in efficacy (potency) and frequency of dosing. A potency of 30C is recommended [
44]. The use of Arnica Montana as a homeopathic product is based on its composition and effects - content of lactones (analgesic, anti-inflammatory, antiecchymotic effect), phenols (antibacterial action), flavanoids (venous tropism). The anti-inflammatory, anti-microbial, antioxidant, and immunomodulatory activities of the chemical compounds in Arnica have been investigated in different models [
47]. It is preferred as a non-pharmacological alternative, due to the proven effect in clinical neonatological and pediatric practice in the treatment of trauma with hematomas, fractures, cephalhematomas and other conditions accompanied by varying degrees of pain [
44,
45]. It is especially preferred in the healing of wounds of different origins [
46]. Additionally, Arnica administered orally in homeopathic dilutions has shown positive clinical effects in reducing postoperative pain, edema, and ecchymosis. Topical application of Arnica combined with oral homeopathic dilutions has been found to have a synergistic effect in reducing postoperative pain[ 48]. In vitro studies show that the most active components of Arnica, as well as other preparations from the Asteraceae family, are helenalin and the secuterpene lactones - 11a,13-dihydrohelenalin and hamisonolide [
48]. First Lyss et al. found that helenalin inhibits the transcription nuclear factor,factor kappa B (NF-kB) by altering and stabilizing the NF-kB/inhibitor of kappa B (I kappa B) complex in T cells, B cells and epithelial cells and abolishes kappa gene expression. This is one of the earliest pieces of evidence of Arnica's anti-inflammatory properties. A later study showed that helenalin could inhibit human neutrophil migration, chemotaxis, 5-lipoxygenase activity, and leukotriene C4 synthetase. It leads to reduced expression of the cell surface receptors CD25, CD28, CD27 and CD120b, which play a key role in the activation of NF-kB in T cells. This supports the mechanism proposed by Lyss in 1997[48-49]. NF-kB activation is associated with the induction of pain and inflammation, characterized by the release of proinflammatory cytokines (tumor necrosis factor-alpha [TNF-a] and interleukin-1beta [IL-1b] and local leukocyte recruitment [
50].
Comparing the non-anesthetised newborns with those who received Arnica D30 showed a lower rating on both pain scales for the anesthetised before and at 5 minutes after the procedure. The effect was most pronounced in those who received Arnica at the 5th minute - a score was achieved showing the absence of pain in this group, which means that the pain sensation is the shortest. When monitoring changes in heart rate during the observed intervals, no significant difference was found. The present study found that transcutaneous oxygen saturation after administration of Arnica D30 was higher and systolic pressure was lower at the 5th minute compared to non-anesthetised and those, who received Sol.Glucosae 25% . It is noteworthy that when taking Arnica D30, the smallest dynamics are recorded in the respiratory and heart rate values before and at the 5th minute after the heel prick. This once again confirms the anesthetic effect (reducing the duration and severity of pain) of the preparation Arnica D30.
In the interval 12-24h. we did not find deviations from the norm for the age of the monitored physiological indicators - heart rate, respiratory rate, oxygen saturation and arterial pressure after anesthesia with Arnica D30.
In our available literature, no data were found on the use of Arnica D30 in the neonatal period and childhood for the treatment of procedural pain, which did not allow us to compare our results with similar studies. To confirm the effect of Arnica Montana, future studies are needed in three areas: inflammatory processes, pain management, and postoperative conditions, necessitating new meta-analyses in a large number of patients [
48]. This will help to validate complementary medicine as part of the therapeutic approach in a wide range of areas.