Maintaining Reduced Noise Levels in a Resource-Constrained Neonatal Intensive Care Unit by Operant Conditioning.

Objective: To evaluate the efficacy of operant conditioning in sustaining reduced noise levels in the neonatal intensive care unit (NICU) Design: Quasi-experimental study on quality of care. Setting: Level III NICU of a teaching hospital in south India. Participants: 26 staff employed in the NICU. (7 Doctors, 13 Nursing staff and 6 Nursing assistants). Intervention: Operant conditioning of staff activity for 6 months. This method involves positive and negative reinforcement to condition the staff to modify noise generating activities. Main outcome measures: Comparing noise levels in decibel: A weighted [dB (A)] before conditioning with levels at 18 and 24 months after conditioning. Decibel: A weighted accounts for noise that is audible to human ears. Results: Operant conditioning for 6 months sustains the reduced noise levels to within 62 dB (A) in ventilator room (95% CI: 60.4 – 62.2) and isolation room (95% CI: 55.8 – 61.5). In the pre-term room, noise can be maintained within 52 dB (A) (95 % CI: 50.8 – 52.6). This effect is statistically significant in all the rooms at 18 months (P = 0.001). At 24 months post conditioning there is a significant rebound of noise levels by 8.6, 6.7 and 9.9 dB (A) in the ventilator, isolation and pre-term room, respectively (P=0.001). Conclusion: Operant conditioning for 6 months was effective in sustaining reduced noise levels. At 18 months post conditioning, the noise levels were maintained within 62 dB (A), 60 dB (A) and 52 dB (A) in the ventilator, isolation and pre-term room, respectively. Conditioning needs to be repeated at 12 months in the ventilator room and at 18 months in the other rooms.

Efficacy of a low cost protocol in reducing noise levels in the neonatal intensive care unit.

Objective. To examine the effectiveness and cost of implementing a noise reduction protocol in a level III neonatal intensive care unit (NICU). Methods. A prospective longitudinal study was done in a level III NICU, wherein a noise reduction protocol that included behavioral and environmental modification was implemented. The noise levels were measured sequentially every hour for 15 days before and after this intervention. The statistical significance of the reduction in noise levels after implementation of the protocol was tested by paired sample student's t-test. Cost was calculated using the generalized cost effectiveness model of the World Health Organisation. The present study has 80 % power with 95 % confidence to measure 2 dB differences between groups for the maximum recommended of 50 dB. Results. The protocol in the present study reduced noise levels in all the rooms of the NICU to within 60 dB with high statistical significance (p< 0.001). The extent of noise reduction in the rooms of the NICU was as follows : ventilator room by 9.58 dB (95 % confidence interval: 6.73 – 12.42, p < 0.001) , stable room by 6.54 dB (95 % confidence interval: 2.92 – 4.16 , p < 0.001), isolation room by 2.26 dB (95 % confidence interval: 1.21 – 3.30, p < 0.001) , pre-term room by 2.37 dB(95 % confidence interval: 1.22 – 3.51, p < 0.001)and extreme preterm room by 2.09 dB (95 % confidence interval: 1.14 – 3.02, p < 0.001). The intervention was most cost-effective in the ventilator room, requiring Rs. 81.09 to reduce 1 dB and least effective in the extreme pre-term room requiring Rs. 371.61 to reduce 1 dB. Conclusion. The high efficacy and affordability of noise reduction protocols justify the need for implementation of these measures as a standard of care in neonatal intensive care units.

Spectral analysis of noise in the neonatal intensive care unit.

OBJECTIVE: To perform spectral analysis of noise generated by equipments and activities in a level III neonatal intensive care unit (NICU) and measure the real time sequential hourly noise levels over a 15 day period. METHODS: Noise generated in the NICU by individual equipments and activities were recorded with a digital spectral sound analyzer to perform spectral analysis over 0.5 - 8 KHz. Sequential hourly noise level measurements in all the rooms of the NICU were done for 15 days using a digital sound pressure level meter . Independent sample t test and one way ANOVA were used to examine the statistical significance of the results. The study has a 90 % power to detect at least 4 dB differences from the recommended maximum of 50 dB with 95 % confidence. RESULTS: The mean noise levels in the ventilator room and stable room were 19.99 dB (A) sound pressure level (SPL) and 11.81 dB (A) SPL higher than the maximum recommended of 50 dB (A) respectively ( p < 0.001). The equipments generated 19.11 dB SPL higher than the recommended norms in 1 - 8 KHz spectrum. The activities generated 21.49 dB SPL higher than the recommended norms in 1 - 8 KHz spectrum ( p< 0.001).The ventilator and nebulisers produced excess noise of 8.5 dB SPL at the 0.5 KHz spectrum. CONCLUSION: Noise level in the NICU is unacceptably high .Spectral analysis of equipment and activity noise have shown noise predominantly in the 1 - 8 KHz spectrum. These levels warrant immediate implementation of noise reduction protocols as a standard of care in the NICU.