Gonçalves Elaine C, Silva Elaine C, Basile Filho Anibal, Auxiliadora-Martins Maria, Nicolini Edson A, Gastaldi Ada C
Department of Orthopaedics, Traumatology and Rehabilitation of the Locomotor System, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
Rev Bras Fisioter. 2012 Sep-Oct;16(5):368-74. doi: 10.1590/s1413-35552012005000037. Epub 2012 Jul 24.
The rapid shallow breathing index (RSBI) is the most widely used index within intensive care units as a predictor of the outcome of weaning, but differences in measurement techniques have generated doubts about its predictive value.
To investigate the influence of low levels of pressure support (PS) on the RSBI value of ill patients.
Prospective study including 30 patients on mechanical ventilation (MV) for 72 hours or more, ready for extubation. Prior to extubation, the RSBI was measured with the patient connected to the ventilator (DragerTM Evita XL) and receiving pressure support ventilation (PSV) and 5 cmH2O of positive end expiratory pressure or PEEP (RSBI_MIN) and then disconnected from the VM and connected to a Wright spirometer in which respiratory rate and exhaled tidal volume were recorded for 1 min (RSBI_ESP). Patients were divided into groups according to the outcome: successful extubation group (SG) and failed extubation group (FG).
Of the 30 patients, 11 (37%) failed the extubation process. In the within-group comparison (RSBI_MIN versus RSBI_ESP), the values for RSBI_MIN were lower in both groups: SG (34.79±4.67 and 60.95±24.64) and FG (38.64±12.31 and 80.09±20.71; p<0.05). In the between-group comparison, there was no difference in RSBI_MIN (34.79±14.67 and 38.64±12.31), however RSBI_ESP was higher in patients with extubation failure: SG (60.95±24.64) and FG (80.09±20.71; p<0.05).
In critically ill patients on MV for more than 72h, low levels of PS overestimate the RSBI, and the index needs to be measured with the patient breathing spontaneously without the aid of pressure support.
快速浅呼吸指数（RSBI）是重症监护病房中预测撤机结果使用最广泛的指标，但测量技术的差异引发了对其预测价值的质疑。
研究低水平压力支持（PS）对患病患者RSBI值的影响。
前瞻性研究，纳入30例接受机械通气（MV）72小时及以上且准备拔管的患者。在拔管前，患者连接呼吸机（DragerTM Evita XL）并接受压力支持通气（PSV）及5 cmH₂O呼气末正压（PEEP）时测量RSBI（RSBI_MIN），然后断开与呼吸机连接并连接到赖特肺量计，记录呼吸频率和呼出潮气量1分钟（RSBI_ESP）。根据结果将患者分为成功拔管组（SG）和拔管失败组（FG）。
30例患者中，11例（37%）拔管失败。组内比较（RSBI_MIN与RSBI_ESP），两组RSBI_MIN值均较低：SG组（34.79±4.67和60.95±24.64），FG组（38.64±12.31和80.09±20.71；p<0.05）。组间比较，RSBI_MIN无差异（34.79±14.67和38.64±12.31），但拔管失败患者的RSBI_ESP较高：SG组（60.95±24.64），FG组（80.09±20.71；p<0.05）。
在接受MV超过72小时的重症患者中，低水平PS会高估RSBI，该指标需要在患者自主呼吸且无压力支持辅助的情况下进行测量。
