Exposure and reactivity of the preterm infant to noise in the incubator

Rodarte, Milena Domingos de Oliveira; Fujinaga, Cristina Ide; Leite, Adriana Moraes; Salla, Cleomara Mocelin; Silva, Caroline Gianna da; Scochi, Carmen Gracinda Silvan

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Sumário

Original Article • CoDAS 31 (5) • 2019 • https://doi.org/10.1590/2317-1782/20192017233 copy

Exposure and reactivity of the preterm infant to noise in the incubator

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Purpose

To evaluate preterm infants’ exposure and reactions to intense noise during incubator care.

Methods

An observational and prospective study was performed in the intermediary care unit of a hospital in Ribeirão Preto (SP). Thirty-five preterm infants participated in the first stage of the study (measuring noise) and 20 in the second (analysis of responses to intense noise). Noise was measured for two hours using a dosimeter, and the responses were video recorded by three cameras connected to a computer. The preterm infants’ responses to an L_max higher than 65 decibels were analyzed.

Results

Every preterm infant presented L_eq above the limit recommended by international organizations, and more than half of the babies had a mean L_eq above the limit permitted by the Brazilian standard. Regarding the babies’ responses to the intense noise, the majority of them showed blink reflex, startle reflex, facial mimics, changed bodily activities or changed sleep and wake state, all with statistically significant differences.

Conclusion

The sound levels measured were intense. The noises that preterm infants are exposed to while being cared for in incubators constitute a stressor event. Sudden, intense noises change their behavioral state and causes reflexive and bodily responses, facial manifestations and changes in their sleep and wake state.

Keywords
Incubators, Infant; Noise; Infant, Premature; Reactivity-stability; Neonatology

		General group	Subgroup
Sex	Male Female Ambiguous genitalia	20 14 1	10 9 1
Birth weight	Range Mean	650-2980g 1406.9g	700-2575g 1369.75g
Current weight	Range Mean	1050-2900g 1586.0g	1150-2530g 1565.0g
Gestational age	Range Mean	185-255d (26w3d-36w3d) 221.80d	185-225d (26w3d-36w3d) 221.25d
Postnatal age	Range	1-83d	1-83d
Corrected age	Range Mean	215-272d (30w5d-38w6d) 243.7d	215 - 272d (30w5d-38w6d) 246.7d

General group
NB	L_eq			L_min	L_max
NB	Mean	% >45 dB^* * Limit set for neonatal care environment by the Consensus Committee on Recommended Design Standards for Advanced Neonatal Care(8) and recommended for the NICU and incubators by the AAP(14);	% >60 dB^ Limit set for incubators by the Brazilian standard IEC 601-2-19(13). Source: the authors	L_min	L_max	% >65 dB*
01	57.7	100	3.3	54.3	79.9	14.2
02	61.2	100	8.3	54.8	89.8	19.2
03	66.6	100	25.8	52.3	85.3	37.5
04	67.5	100	10.8	53.8	92.3	19.2
05	57.7	100	4.2	55.0	81.3	15.0
06	57.8	100	7.5	54.9	80.7	20.0
07	60.9	100	6.7	49.5	88.7	14.2
08	55.5	100	2.5	52.1	85	5.8
09	56.6	100	5.0	53.6	81	18.3
10	71.4	100	12.5	52.2	95.6	27.5
11	59.7	100	20.0	55.6	82.1	37.5
12	56.4	100	3.3	52.7	85.7	12.5
13	71.9	100	15.0	48.8	90.8	26.7
14	57.5	100	11.7	51.8	82	20.8
15	62.5	100	15.0	53.6	85.1	23.3
16	65.1	100	8.3	55.1	87.6	12.5
17	62.7	100	29.2	48.9	86.3	45.8
18	74.4	100	25.8	51.9	92.1	33.3
19	66.2	100	20.0	47.1	89	29.2
20	55.8	100	0.8	53.1	78.7	3.3
21	67.9	100	39.2	55.7	90.6	48.3
22	70.7	100	49.2	52.3	95.9	59.2
23	68.1	100	15.0	56.6	90.3	22.5
24	63.4	100	10.8	54	86.7	17.5
25	56.3	100	2.5	54	77.2	5.8
26	54.0	100	1.7	48.3	82.4	12.5
27	65.6	100	100	61.6	89.8	27.5
28	56.6	100	0.0	55.3	67.7	3.3
29	56.7	100	5.8	46.9	85	20.8
30	75.3	100	25.8	54.4	96.8	33.3
31	64.3	100	10.8	54	97.2	14.2
32	65.4	100	90.8	52.3	81.4	92.5
33	56.5	100	2.5	52.9	79.5	14.2
34	58	100	2.5	56.5	80.1	5.8
35	55.6	100	1.7	52.6	76.1	7.5
Subgroup
NB	Leq			Lmin	Lmax
NB	Mean	% >45 dB*	% >60 dB**	Lmin	Lmax	% >65 dB*
02	61.2	100	8.3	54.8	89.8	19.2
03	66.6	100	25.8	52.3	85.3	37.5
04	67.5	100	10.8	53.8	92.3	19.2
05	57.7	100	4.2	55.0	81.3	15.0
06	57.8	100	7.5	54.9	80.7	20.0
07	60.9	100	6.7	49.5	88.7	14.2
09	56.6	100	5.0	53.6	81	18.3
10	71.4	100	12.5	52.2	95.6	27.5
11	59.7	100	20.0	55.6	82.1	37.5
12	56.4	100	3.3	52.7	85.7	12.5
14	57.5	100	11.7	51.8	82	20.8
17	62.7	100	29.2	48.9	86.3	45.8
22	70.7	100	49.2	52.3	95.9	59.2
23	68.1	100	15.0	56.6	90.3	22.5
24	63.4	100	10.8	54.0	86.7	17.5
25	56.3	100	2.5	54.0	77.2	5.8
26	54.0	100	1.7	48.3	82.4	12.5
27	65.6	100	100	61.6	89.8	27.5
30	75.3	100	25.8	54.4	96.8	33.3
32	65.4	100	90.8	52.3	81.4	92.5

Responses physiological		Previous period			Subsequent period			p (α = 0.05)
Responses physiological		Var	Mean (SD)	M	Var	Mean (SD)	M	p (α = 0.05)
HR (bpm)	mean	114.0-182.9	140.6 (16.0)	138.0	101.4-162.5	138.0 (15.6)	136.9	0.983
	minimum	114.0-162.0	134.2 (14.2)	135.0	69.0-154.0	129.7 (19.3)	132.0	0.679
	maximum	114.0-187.0	145 (16.3)	144.5	114.0-187.0	146.3 (17.2)	148.0	0.517
SaO₂ (%)	mean	87.2-97.8	95.3 (2.7)	96.2	90.0-98.0	95.5 (2.1)	95.9	0.679
	minimum	86.0-97.0	93.8 (3.5)	95.0	84.0-98.0	94.0 (3.3)	95.0	0.566
	maximum	88.0-99.0	96.2 (2.7)	97.0	90.0-98.0	96.5 (1.9)	97.0	0.206

	Previous period	Subsequent period	p (α = 0.05)
Activity reflex (19 NBs: BR 20 NBs: Startle and Moro)	20: no reflection pattern	9: BR	-
		1: startle reaction
		3: BR + startle
		7: no reflex activity
Facial mimicry (19 NBs)	18: no facial activity	11: no facial activity	0.012
Facial mimicry (19 NBs)	1: score 0.8	8: score 0.2 to 1.4	0.012
Bodily activity	19: no or very little movement	9: no or very little movement	0.003
(20 NBs)	1: regular, small and continuous movements, relaxed	6: regular, small and continuous movements, relaxed
		3: tense, irritated and not relaxed
		2: movement with a lot of force, very tense
Sleep and wake state (20 NBs)	14: deep sleep	7: deep sleep	0.005
	4: active sleep	8: active sleep
	2: drowsy	1: drowsy
	0: alert	1: alert
	0: restless	3: restless
	0: crying	0: crying

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[1] Conflict of interests: nothing to declare.