Avaliação do pico de pressão, do volume corrente e da freqüência respiratória durante ventilação de carneiros prematuros utilizando balão auto-inflável

Abstract

Objective: To evaluate the peak inspiratory pressure, tidal volume and respiratory rate achieved during manual ventilation of premature lambs, using a self-inflating bag. Methods:In this descriptive, experimental study, five pairs of physicians, selected at random among 35 neonatologists working at a neonatal intensive care unit and with experience in the resuscitation of newborn infants, ventilated five intubated premature lambs using a self-inflating bag. Pressure and flow monitor signals were passed through a transducer and digitized for recording and analysis. Tidal volume and pressure curves were obtained from the integral of flow rate, at peak, during the last 50 seconds of every fifth minute, and analyzed.Results: Median pressure was 39.8 (IQ 25-75% 30.2-47.2) cmH 2 O; being below 20 in 1.1% of cases and above 40 in 49.1%. Seven out of 10 physicians produced more than six pressure peaks of over 40 cmH 2 O. Median tidal volume/kg was 17.8 (IQ 25-75% 14.1-22.4) mL, being below 5 mL in 0.1% of cases and greater than or equal to 20 mL in 37.7%. All of the physicians propelled five or more ventilation cycles with tidal volume/kg of 20 mL or more. Respiratory rate was between 30 and 60 cycles/minute in 65.9% of cases, being below 30 in 6.8% of cases and over 60 in 27.3% of cases.Conclusions: There was major variation in peak inspiratory pressure and tidal volume/kg values, which were in many cases elevated, attaining levels that habitually cause biotrauma, while respiratory rates were adequate in the majority of cases.

An Evaluation of Peak Inspiratory Pressure, Tidal Volume, and Ventilatory Frequency During Ventilation With a Neonatal Self-Inflating Bag Resuscitator

“…We also found that nearly half of the participants delivered breaths at insufficient rates (Ͻ 40 breaths/min), in contrast with the findings by Rezende at al, 17,18 who showed good adequacy for f. This discrepancy is possibly due to differences in the volunteer population. Rezende et al 17,18 studied a small group of experienced physicians, whereas we studied a larger sample of subjects from 5 different professions who work with neonatal intensive care, with variable experience in resuscitation.…”

“…18 Both studies showed wide variability of delivered pressures and volumes, which frequently exceeded standard values for safe ventilation. 17,18 The present study shows that the high variability does not seem to be an artifact due to restricted sample size, because it was still observed even with a considerably greater number of volunteers (n ϭ 172).…”

“…18 Both studies showed wide variability of delivered pressures and volumes, which frequently exceeded standard values for safe ventilation. 17,18 The present study shows that the high variability does not seem to be an artifact due to restricted sample size, because it was still observed even with a considerably greater number of volunteers (n ϭ 172). This is in agreement with the results of Roehr et al, 25 in which high variability of PIP (2.7-58.9 cm H 2 O) and V T (1-14.6 mL) was observed in a sample of 120 volunteers during ventilation of a neonatal mannequin with a self-inflating bag.…”

“…2 There is evidence that the ventilatory parameters delivered with this device may be influenced by several factors such as circuit con-figuration and brand, 4,5 the use of 1 or 2 hands to ventilate, 4,6-11 and operator's hand size, 4,7,12 profession, 6,13 and experience. 14 This may cause high variability of the absolute values of these parameters, 11,[15][16][17][18] causing delivery of either excessive or insufficient values. In the former case the risk for pulmonary injury (barotrauma and volutrauma) is increased, and in the latter there is a higher risk for hypoventilation.…”

É preciso repensar o conceito da ventilação manual com balão autoinflável em recém-nascidos

“…Isso resulta em lesão pulmonar por vários mecanismos, incluindo a exposição a elevadas concentrações de oxigênio, o atelectrauma e o volutrauma (3) . Neste sentido, os resultados publicados por Zaconeta et al (4) nesta edição da Revista Paulista de Pediatria têm o mérito de acrescentar mais informação a este assunto produzida por um grupo com tradição em pesquisa nesta área (5,6) . Um dos pontos fortes do trabalho é o estudo de uma população pouco avaliada na literatura pediátrica: profissionais não-médicos que atuam na linha de frente das emergências ocorridas com crianças fora do ambiente hospitalar.…”