Comparative Effect of the Smells of Amniotic Fluid,Breast Milk,and Lavender on Newborns’ Pain During Heel Lance

Abstract

Introduction:

The aim of this randomized controlled experimental study was to evaluate the effect of the smells of amniotic fluid, breast milk, and lavender on the pain of newborns during heel lance.

Methods:

The sample of the study consisted of 102 newborn infants who complied with the sampling criteria between August and November, 2011. The newborns smelled the samples (lavender, breast milk, amniotic fluid, and distilled water) for 5 minutes before the heel lance until 5 minutes afterward. The Neonatal Infant Pain Scale (NIPS), heart rate, and oxygen saturation were evaluated 1 minute before, during, and 1 minute after the heel lance. Data were evaluated by descriptive statistics, chi-square, intraclass correlation analysis, Spearman's rho correlation, Bonferroni's advanced analysis, Shapiro–Wilk, Kruskal–Wallis, Mann–Whitney U, Friedman, and Dunnett's tests.

Results:

The newborns in the control group had severe pain and the newborns in the breast milk, amniotic fluid, and lavender groups had moderate pain during the heel lance (p < 0.05). While the NIPS score of the newborns in the lavender group was lower than the breast milk and amniotic fluid groups during the heel lance, it was lower in the breast milk and amniotic fluid groups than the lavender group afterward. The lowest falls in oxygen saturation and increased in heart rate were in the breast milk and lavender groups during heel the lance.

Conclusion:

The smells of lavender and breast milk prevent the increased heart rates, NIPS, falling oxygen saturation, and reduced pain during the invasive procedures in newborns more than amniotic fluid or control group.

Introduction

Pain is a complex and multidimensional fact that affects the psychosocial and mental health of individuals.^1,2 Acute pain due to medical procedures causes behavioral stress, physiological imbalances, and a reduced pain threshold.^3–6 To avoid these negative outcomes, the pain of newborns should be evaluated completely and accurately, and the negative effects of pain should be minimized with effective pain-relieving methods.^2,4,7–10 Pharmacological and nonpharmacological methods are used for effective pain treatment. However, the pharmacological procedures’ side effects have increased interest in alternative and complementary methods.^1,11,12 A variety of practices such as positioning, swaddling, shaking, holding on the lap, kangaroo care, massage, acupuncture, acupressure, Reiki, pacifiers, sweet solutions (sucrose, glucose), breastfeeding, maternal voice and smell, breast milk, singing a lullaby, aromatherapy and having infants smell familiar smells are among the complementary and alternative methods for reducing the pain and stress of newborns in the literature.^{1,2,10,13–19} Pain management is more effective when these practices are combined.⁴ Various studies have shown that infants can perceive smells at birth, and that the smells of infants’ mothers are effective in pain management.^4,16,20–24 The aim of this randomized controlled experimental study was to evaluate the effect of the smells of amniotic fluid, breast milk, and lavender on reducing newborns’ acute pain due to a heel lance.

Materials and Methods

This comparative, single-blinded, randomized controlled study involved 135 newborns who received treatment and care in Finike State Hospital Obstetric and Pediatric Department between August and November 2011, who complied with the sampling criteria and whose blood was drawn for routine metabolic screening. Of them, 33 were excluded from the study because 10 parents did not agree to participate. Heel lance was done to both heels of 15 newborns, and the amniotic fluid of 8 mothers was mixed with blood. Consequently, the study was completed with 102 newborns: 27 in the lavender group, 24 in the breast milk group, 26 in the amniotic fluid group, and 25 in the control group. Newborns were selected for the groups randomly from an opaque envelope. Power analysis at the end of the study found its power to be 0.87.

Sampling Criteria for Newborns: The study included newborns whose gestational ages were between 38 and 42 weeks and whose birth weights were 2,500 g or more, who were delivered by cesarean section, and who had not received any pharmacological or nonpharmacological treatments. The newborns’ pain severity was evaluated using the NIPS developed by Lawrence.²⁵ Oxygen saturation and heart rate by Jerry II El type pulse oximeter. The NIPS measures six behavioral responses: facial expression, crying, manner of respiration, arms, legs, and wakefulness to evaluate the pain of newborns. While crying is scored with three points (0-1-2), other behaviors are scored with only two points (0–1). The highest and lowest possible scores on the NIPS are 7 and 0, respectively. Scores between 0 and 2 are considered to be pain free. Scores of 3 and 4 indicate moderate pain, and scores over 4, severe pain. The general pain status was evaluated before the heel lance using this scale, and changes during and after the procedure were observed.^25,26

Written consent was obtained from the Ethics Committee of the Erciyes University Medical Faculty, from the hospital where the study was conducted, and from the parents.

Data Collection: A training program on pain in newborns, pain evaluation, and nursing management for pain was planned to help the nurses to do accurate and reliable pain evaluation. The training was held three times at 2-week intervals before conducting the study. Each training session was approximately 30 minutes. The first two sessions were a slideshow on a laptop and an oral presentation using questions and answers and demonstrations. The third training was actual practice with patients. A pilot test was carried out with 20 newborns, 5 newborns from each group, to assess the appropriateness and usefulness of the data collection tools, and to improve the nurses’ pain evaluation skill. The newborns involved in the pilot test were excluded from the study.

Routine nursing care was given to the families and newborns in all groups on the first day after birth. On the second day, infants were breastfed half an hour before the invasive procedure. The newborns smelled different odors only before, during, and after the heel lance. All samples were put in 5-mL liquid-tight glass bottles, heated by double boiling, and kept at 36–37°C, but the attending nurses were not informed which odor sample they would be administering to the infants. Before having the infants smell the odor samples, the experimenter prepared 5 mL of each odor sample into a 20-mL sample tube. The sample tube with odor samples was held at a 10-cm distance from the infant's nose from 5 minutes before the invasive procedure until 5 minutes afterward. The blood test for metabolic screening was administered by heel-lance between 10:00 and 12:00 a.m. by the attending nurse. The infants’ heels were rubbed and their skins were cleaned with alcohol before the heel lance. For the heel lance, each newborn was taken to a quiet room at 23–26°C away from the other infants’ crying voices. Blood lancet 22 G was used for the heel lance while the newborns were quiet and awake. The heel lances of the newborns in the lavender, breast milk, amniotic fluid, and control groups took 1.1 ± 0.32 minutes on average. The time of heel lance did not differ by group (p = 0.187, F: 1.632). The heel lance was carried out only once for each newborn. Infants with repetitive interventions were excluded from the study.

Preparation of the Smell Samples: A 5 mL amniotic fluid sample was taken by the physician during cesarean delivery and kept in a refrigerator at 2–8°C. A 5 mL breast milk sample was taken from the mother of each newborn by milking their breasts 2 hours after breakfast on the second day after birth. The lavender sample was prepared by dripping a drop of lavender oil into 20 mL distilled water in a separate 20-mL sample tube for each newborn.²⁷ For the control group, 5 mL distilled water was put into 20-mL sample tube. The NIPS, heart rate, and oxygen saturation were measured in this study to evaluate physiological response to pain. Two trained neonatology nurses blinded as to the content of vials evaluated the NIPS of the newborns in all groups from 1 minute before the invasive procedure to 1 minute afterward. Physiological variables, such as heart rate and oxygen saturation, were recorded using the Jerry II El type pulse oximeter for 1 minute before the invasive procedure, 1 minute during the procedure, and 1 minute after the procedure. The oxygen saturation levels and heart rates of the infants in four groups were recorded as the highest measurement in each of the 3 minutes. The relationships between the NIPS scores obtained by two observers independently under the same conditions before and after the heel lance were identified using intraclass correlation coefficient (ICC) to determine the reliability of the NIPS used in the study. The ICC values before and after the heel lance were 0.98 and 0.94, respectively. The data were evaluated on a computer using the appropriate descriptive statistics, chi-square, intraclass correlation analysis, Spearman's rho correlation, Bonferroni's advanced analysis, Shapiro–Wilk, Kruskal–Wallis, Mann–Whitney U, Friedman, and Dunnett's tests. Statistical significance was defined at a level of p < 0.05.

Results

The newborns in the lavender, breast milk, amniotic fluid, and control groups were similar in terms of gender, birth weight, and 5-minute Apgar score (Table 1). The NIPS evaluation of the pain of the newborns during the heel lance procedure found that the newborns in all groups had no pain before heel lance. The newborns in the control group had severe pain (scores of 4 or more) and the newborns in the breast milk, amniotic fluid, and lavender groups had moderate pain (scores of 3 and 4) during the heel lance. A statistically significant difference was found between the control group and all the study groups (p < 0.05). The NIPS score of the newborns in the lavender group was lower than the breast milk and amniotic fluid groups during the heel lance, it was lower in the breast milk and amniotic fluid groups than the lavender group after heel lance (Table 2).

Table 1.

Similarity Criteria of the Newborns

	Lavender group (n = 27)		Breast milk group (n = 24)		Amniotic fluid group (n = 26)		Control group (n = 25)
Similarity criteria	n	%	n	%	n	%	n	%	Test	p
Gender
Female	13	48.1	12	50	14	53.8	15	60	0.83^a	0.84
Male	14	51.9	12	50	12	46.2	10	40
	\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $\bar {x}$ \end{document} ± SD	Med (Min–Max)	\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $\bar {x}$ \end{document} ± SD	Med (Min–Max)	\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $\bar {x}$ \end{document} ± SD	Med (Min–Max)	\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $\bar {x}$ \end{document} ± SD	Med (Min–Max)	F^b	p
Birth weight (gr)	3,402.2 ± 384.1	3,350 (2,730–4,200)	3,336.2 ± 351.5	3,290 (2,640–4,070)	3,401.0 ± 223.7	3,360 (3,000–3,850)	3,401.6 ± 309.8	3,450 (2,800–4,000)	0.25	0.86
Apgar score (at 5 minutes)	9.96 ± 0.19	10.00 (9–10)	10.00 ± 0.00	10.00 (10–10)	10.00 ± 0.00	10.00 (10–10)	10.00 ± 0.00	10.00 (10–10)	0.92	0.43

Kruskal–Wallis.

ANOVA.

SD, standard deviation.

Table 2.

Neonatal Infant Pain Scale Score Averages of the Newborns in the Lavender, Breast Milk, Amniotic Fluid, and Control Groups Before, During, and After the Heel Lance

		NIPS assessment
Group	Measurements	\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $\bar {x}$ \end{document} ± SD	Med (Min–Max)
Lavender group (n = 27)	Before heel lance	0.04 ± 0.13	0.0 (0.0–0.5)
	During heel lance	2.91 ± 2.47	2.0 (0.0–7.0)
	After heel lance	0.87 ± 1.16	0.0 (0.0–4.0)
Breastfed group (n = 24)	Before heel lance	0.0 ± 0.0	0.0 (0.0–0.0)
	During heel lance	3.31 ± 2.39	3.0 (0.0–7.0)
	After heel lance	0.67 ± 0.90	0.0 (0.0–3.0)
Amniotic fluid group (n = 26)	Before heel lance	0.0 ± 0.0	0.0 (0.0–0.0)
	During heel lance	3.90 ± 2.47	3.2(0.0–7.0)
	After heel lance	0.71 ± 1.02	0.0 (0.0–3.0)
Control group (n = 25)	Before heel lance	0.0 ± 0.0	0.0 (0.0–0.0)
	During heel lance	5.20 ± 2.10	6.5 (1.5–7.0)
	After heel lance	1.02 ± 1.12	1.0 (0.0–5.0)

		F	p
Test	Time	0.00	0.997
	Group	3.51	0.015
	Time × Group	2.27	0.036

NIPS, neonatal infant pain scale.

Before the heel lance procedure, heart rate averages of newborns was 136/min, 128/min, 118/min, and 119/min in the breast milk, lavender, amniotic fluid, and control groups, respectively. Increasing levels in heart rate during procedure were noted in the breast milk group (13 beats), lavender group (16 beats), control group (20 beats), and amniotic group (22 beats), respectively. The increase in levels of heart rate was minimal in the breast milk group (5 beats) and amniotic fluid group (10 beats) after heel lance as compared with the rate before heel lance. A statistically significant difference was found between the newborn groups in terms of heart rates (f = 16.63, p < 0.001) (Table 4). As our expectation, it was found that the breast milk group was at an advantage according to other groups after and before heel lance.

The oxygen saturation level of newborn was between 97–99% for all groups before the heel lance procedure. The decrease in oxygen saturation during the heel lance procedure was 1% in the breast milk and the lavender groups and 2–3% in the amniotic and control groups. The lowest falls in oxygen saturation were in the breast milk and lavender groups. The differences between the control and the lavender and breast milk groups were found to be statistically significant (p < 0.05), whereas the difference between the control and the amniotic fluid group was not (Table 3).

Table 3.

Oxygen Saturation Averages of the Newborns in the Lavender, Breast Milk, Amniotic Fluid, and Control Groups Before, During, and After the Heel Lance

		Oxygen saturation average
Group	Measurements	\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $\bar {x}$ \end{document} ± SD	Med (Min–Max)
Lavender group (n = 27)	Before heel lance	98.77 ± 1.05	99.00 (96–100)
	During heel lance	97.37 ± 1.80	97.00 (93–100)
	After heel lance	97.81 ± 1.84	98.00 (92–100)
Breastfed group (n = 24)	Before heel lance	97.66 ± 1.46	98.00 (95–100)
	During heel lance	96.40 ± 1.66	97.00 (92–99)
	After heel lance	96.70 ± 1.33	96.50 (94–99)
Amniotic fluid group (n = 26)	Before heel lance	98.70 ± 0.81	99.00 (97–100)
	During heel lance	96.19 ± 1.38	96.00 (94–99)
	After heel lance	97.00 ± 0.97	97.00 (95–99)
Control group (n = 25)	Before heel lance	98.80 ± 1.29	99.00 (95–100)
	During heel lance	96.44 ± 1.98	96.00 (90–99)
	After heel lance	97.12 ± 1.66	97.00 (93–100)

		F	p
Test	Time	0.00	0.998
	Group	8.48	<0.001
	Time × Group	1.70	0.11

Discussion

Lavender oil is said to be relaxing and have a sedative effect on the amygdala.^27,28 Kane et al.²⁸ determined that lavender reduces the severity of the pain of newborns during bandage changes. Razaghi et al.²⁹ found that the smell of lavender effectively reduces the pain, but is not effective in reducing crying time during venous blood sampling. Lavender is considered to be able to reduce pain symptoms due to its sedative, antispasmodic, and anticolic properties.³⁰The findings of this study and in the literature show that the smell of lavender effectively reduces the pain and stress of newborns during painful procedures due to its tranquilizing effect. Maternal smells are reported to represent safety to newborns and reduce their pain and stress.^16,20 Nishitani et al.²² also found that behavioral responses and saliva cortisol levels and pains of the newborns who smelled their own mother's breast milk were significantly lower than those of newborns who smelled other mothers’ breast milk or formula. Varendi et al.²¹ found that newborns who smelled amniotic fluid cried for a shorter time than newborns who smelled breast milk or those in the control group. In another study on the effect of smells on pain, the crying newborns were made to smell their own mother's clothes, other mothers’ clothes, and new clothes. The study found that newborns’ respond more positively to the smell of their own mothers.²⁰ Rattaz et al.²³ found that breast milk and vanilla smells reduced newborns’ grimaces, and the smell of breast milk alone was effective in reducing the stress of newborns after taking blood. Goubet et al.²⁴ determined that the newborns who smelled familiar smells cried 32% less than the control group or a group who smelled vanilla during the heel lance. Jebreili et al.¹⁶ found that breast milk and vanilla effectively reduced the pain of newborns during the heel lance, and that the smell of breast milk was more effective than the smell of vanilla.

Various studies have shown that familiar or aromatic smells, white noise, sucrose, massage, music, touch, fetal position, etc., have a positive effect on vital signs such as heart rates and oxygen saturation and relax newborns and children.^2,17,31–34 The heart rate and oxygen saturation values were evaluated as part of the physiological evaluation during the painful procedure in this study. The lowest increase in heart rate were observed in the breast milk group and then in the lavender, control, and amniotic fluid groups, respectively, during heel lance. The lowest falls in oxygen saturation were in the breast milk and lavender groups. The differences between the control and the lavender and breast milk groups were found to be statistically significant, whereas the difference between the control and the amniotic fluid group was not (Tables 3 and 4). These findings demonstrate that the smells of lavender and breast milk prevent increased heart rates and falling oxygen saturation during invasive procedures on newborns more than the smell of amniotic fluid or no smell.

Table 4.

Heart Rate Averages of the Newborns in the Lavender, Breast Milk, Amniotic Fluid, and Control Groups Before, During, and After the Heel Lance

		Heart rate average
Group	Measurements	\documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes{10}{9}{7}{6}\begin{document} $\bar {x}$ \end{document} ± SD	Med (Min–Max)
Lavender group (n = 27)	Before heel lance	128.07 ± 9.17	127.00 (114–144)
	During heel lance	144.15 ± 18.13	140.00 (121–201)
	After heel lance	141.52 ± 18.77	139.00 (117–211)
Breastfed group (n = 24)	Before heel lance	136.12 ± 7.60	133.50 (124–151)
	During heel lance	149.50 ± 13.5	152.00 (121–177)
	After heel lance	141.29 ± 9.71	141.50 (123–164)
Amniotic fluid group (n = 26)	Before heel lance	118.73 ± 10.3	119.00 (102–148)
	During heel lance	140.77 ± 13.4	141.50 (112–166)
	After heel lance	128.50 ± 26.6	132.50 (111–161)
Control group (n = 25)	Before heel lance	119.16 ± 10.5	117.00 (104–143)
	During heel lance	139.96 ± 13.5	138.00 (112–163)
	After heel lance	133.80 ± 12.5	133.00 (115–157)

		F	p
Test	Time	0.00	0.99
	Group	16.63	<0.001
	Time × Group	1.85	0.08

Aoyama et al.³⁵ determined that the smell of breast milk increased blood flow oxygenation in the orbitofrontal region more than other smells. Yılmaz and Arıkan¹⁷ found that the heart rates and oxygen saturation levels of newborns given sucrose during heel lancing was higher than those of newborns who were given breast milk and pacifiers. Örs et al.³⁶ studied the pain of newborns and found that the changes in the heart rates of the newborns given sucrose were lower than those who were given breast milk. In another study, no positive change was observed in the active touching and crying time, heart rates, and respiratory rates during an invasive procedure; however, oxygen saturation was observed to fall less than it did in the control group.³⁷ This study confirms that nonpharmacological methods used for painful procedures positively affect vital signs such as heart rate or oxygen saturation.

Conclusion

The results of this study indicate that the NIPS score of the newborns in the lavender group was lower than that of the breast milk and amniotic fluid groups during the heel lance, and was lower in the breast milk and amniotic fluid groups than in the lavender group afterward. The smells of lavender and breast milk minimized an increase in heart rates and a reduction of oxygen saturation during invasive procedures on newborns more than amniotic fluid or no smell. In conclusion, the smell of lavender can be recommended as an alternative method in the care of the infant during invasive procedures or in cases where breast milk is lacking or cannot be used. However, further research should be conducted on the effect of smells on the pain of newborns in different settings and with different intensities.

Footnotes

Disclosure Statement

No competing financial interests exist.

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