Objective: To investigate the efficacy of high flow nasal cannula (HFNC) in children with acute respiratory failure. Methods: A prospective study was conducted. A total of 153 patients aged from 1 to 14 years with acute respiratory failure were enrolled, who were admitted to pediatric intensive care unit (PICU) of Shanghai Children's Hospital from January 2018 to December 2019. HFNC success was defined as no need for invasive mechanical ventilation and successfully withdrawn from HFNC, while HFNC failure was defined as need for invasive mechanical ventilation. HFNC at a flow rate of 2 L/(kg·min) (maximum ≤ 60 L/min) with inhaled oxygen concentration (FiO2) between 0.30 and 1.00 was applied to maintain percutaneous oxygen saturation (SpO2) of 0.94-0.97. Parameters including arterial partial pressure of oxygen (PaO2), partial pressure of carbon dioxide in artery (PaCO2), SpO2 and PaO2/FiO2 were collected before and during the application of HFNC at 1 h, 6 h, 12 h, 24 h and 48 h, as well as over 48 h after HFNC withdrawn. Comparison between the groups was performed by student t test, Mann-Whitney U test or chi-square test. The sensitivity and specificity of the above parameters in predicting HFNC success were evaluated by receiver operating characteristic (ROC) curve. Results: A total of 153 children (70 males and 83 females) were enrolled. Among them, 131 (85.6%) cases were successfully weaned off from HFNC and 22 (14.4%) failed. The duration of HFNC was 57 (38, 95) hours in the successful group, and the PaO2/FiO2 before HFNC application and after HFNC was withdrawn were 187 (170, 212) mmHg (1 mmHg=0.133 kPa) and 280 (262, 292) mmHg, respectively. The duration of HFNC in the failure group was 19 (9, 49) hours, and the PaO2/FiO2 before HFNC application and after HFNC withdrawn were 176 (171, 189) mmHg and 159 (156, 161) mmHg, respectively. The values of PaO2/FiO2 were significantly higher in the successful group than those in the failed group at using HFNC initially 1 h (196 (182, 211) vs. 174 (160, 178) mmHg, Z =-5.105, P<0.01), 6 h (213 (203, 220) vs. 168 (157, 170) mmHg, Z =-6.772, P<0.01), 12 h (226 (180, 261) vs. 165 (161, 170) mmHg, Z =-4.308, P<0.01), 24 h (229 (195, 259) vs. 165 (161, 170) mmHg, Z=-4.609, P<0.01) and 48 h (249 (216, 273) vs. 163 (158, 169) mmHg, Z =-4.628, P<0.01) after the HFNC application, and over 48 h after HFNC was withdrawn (277 (268, 283) vs. 157 (154, 158) mmHg, Z=-3.512, P<0.01). Moreover, the PaO2 levels were significantly higher in the successful group than those in the failed group using HFNC initially at 1 h (73.7 (71.0, 76.7) vs. 70.0 (66.2, 71.2) mmHg, Z=-4.587, P<0.01) and 6 h (79.0 (75.0, 82.0) vs. 71.0 (62.0, 72.0) mmHg, Z=-5.954, P<0.01) after HFNC application. Also, the SpO2 levels showed the same differences at 1 h (0.96 (0.95, 0.96) vs. 0.94 (0.92, 0.94), Z =-4.812, P<0.01) and 6 h (0.96 (0.95, 0.97) vs. 0.94(0.91, 0.95), Z=-5.024, P<0.01) after HFNC application. Forty eight hours after HFNC was withdrawn, the PaO2 (88.0 (81.7, 95.0) vs. 63.7 (63.3, 66.0) mmHg, Z =-3.032, P<0.01) and SpO2 (0.96 (0.94, 0.98) vs. 0.91 (0.90, 0.92), Z=-3.957, P<0.01) were also significantly higher in the successful group. Regarding the HFNC complications, there was one case with atelectasis and one with pneumothorax in the failure group. HFNC was used as sequential oxygen therapy after extubation in 79 children, successful in all. ROC curve showed that the area under curve of PaO2/FiO2 in predicting HFNC success was 0.990, and the optimal cut-off value was 232 mmHg with the 95%CI of 0.970-1.000 (P<0.01). Conclusions: HFNC could be used as a respiratory support strategy for children with mild to moderate respiratory failure and as a sequential oxygen therapy after extubation. The PaO2/FiO2 when HFNC withdrow is the optimal index to evaluate the success of HFNC application.
目的： 探讨经鼻导管高流量氧疗（HFNC）在儿童呼吸衰竭中的应用效果。 方法： 前瞻性研究，对象为2018年1月至2019年12月上海交通大学附属儿童医院儿童重症监护病房（PICU）收治的1~14岁符合纳入标准的153例急性呼吸衰竭患儿。HFNC成功定义为治疗过程中未升级为有创机械通气并成功撤离HFNC，HFNC失败定义为需要升级为有创机械通气。HFNC设置流量2 L/（kg·min）（最大≤60 L/min），吸入氧浓度（FiO2）0.30~1.00，维持经皮氧饱和度（SpO2） 0.94~0.97。观察成功组和失败组在应用HFNC前及应用后1、6、12、24、48 h及超过48 h撤机时动脉血氧分压（PaO2）、动脉血二氧化碳分压（PaCO2），SpO2、PaO2/FiO2等指标的差异。组间比较采用t检验、Mann-Whitney U检验或χ²检验。应用受试者工作特征（ROC）曲线评估呼吸相关临床参数预测HFNC治疗成功的灵敏度和特异度。 结果： 153例患儿中男70例、女83例，HFNC成功组131例（85.6%），失败组22例（14.4%）。成功组HFNC时间为57（38， 95）h，起始治疗和全部撤机时PaO2/FiO2分别为187 （170， 212） mmHg（1 mmHg=0.133 kPa）和280 （262， 292） mmHg。失败组HFNC时间为19 （9， 49） h，起始与全部撤机时PaO2/FiO2分别为176 （171， 189） mmHg和 159 （156， 161） mmHg。初始使用HFNC成功组与失败组PaO2/FiO2比较，HFNC后1 h［196（182， 211）比174（160， 178）mmHg， Z=-5.105， P<0.01］、6 h［213（203， 220）比168（157， 170）mmHg， Z=-6.772， P<0.01］、12 h［226（180， 261）比165（161， 170）mmHg， Z=-4.308， P<0.01］、24 h［229（195， 259）比165（161， 170）mmHg， Z=-4.609， P<0.01］、48 h［249（216， 273）比163（158， 169） mmHg， Z=-4.628， P<0.01］及超过48 h撤机时［277（268， 283）比157（154， 158） mmHg， Z=-3.512， P<0.01］差异均有统计学意义。初始使用HFNC成功组和失败组PaO2在应用后1 h［73.7（71.0， 76.7）比70.0（66.2， 71.2）mmHg， Z=-4.587， P<0.01］、6 h［79.0（75.0， 82.0）比71.0（62.0， 72.0）mmHg， Z=-5.954， P<0.01］差异有统计学意义；成功组和失败组SpO2在应用后1 h［0.96（0.95， 0.96）比0.94（0.92， 0.94）， Z=-4.812， P<0.01］、6 h［0.96（0.95， 0.97）比0.94（0.91， 0.95）， Z=-5.024， P<0.01］差异均有统计学意义；两组HFNC>48 h撤机时PaO2［88.0（81.7， 95.0）比63.7（63.3， 66.0） mmHg， Z=-3.032， P<0.01］、SpO2［0.96（0.94， 0.98）比0.91（0.90， 0.92）， Z=-3.957， P<0.01］差异均有统计学意义。失败组主要并发症为肺不张1例、气胸1例。HFNC作为拔管后序贯氧疗79例，均获得成功。通过ROC曲线分析HFNC应用成功多因素的灵敏度和特异度显示HFNC撤机PaO2/FiO2的ROC曲线下面积最大，为0.990，最佳截断值为232 mmHg，95%CI为0.970~1.000（P<0.01）。 结论： HFNC可作为PICU儿童轻、中度呼吸衰竭的呼吸支持措施，也可作为有创呼吸机撤离后的序贯氧疗。撤机时PaO2/FiO2为评估HFNC应用成功的最优指标。.
Keywords: Child; Prospective studies; Respiratory insufficiency.