校正胎龄40周时早产儿潮气呼吸肺功能研究

目的初步探讨早产儿在校正胎龄40周时的潮气呼吸肺功能状况。方法选择我院2011年1～9月新生儿科收治的早产儿,机械通气组和非机械通气组各入选20例,于校正胎龄40周时分别测定潮气呼吸肺功能的各项指标,与同期产科分娩、胎龄39～40周健康对照组(分别入选剖宫产组30例和阴道分娩组20例)生后5～7天时的潮气呼吸肺功能相比较。结果机械通气组吸气时间(TI,s)、呼气时间(TE,s)较阴道分娩组和非机械通气组明显延长[TI:(0.68±0.17)比(0.52±0.06)、(0.53±0.11),TE:(0.72±0.15)比(0.59±0.13)、(0.57±0.09),P<0.05],呼吸频率(RR,次/min)明显降低[(44.4±7.7)比(56.2±10.8)、(56.1±9.5),P<0.05)];两个早产儿组达峰时间比(TPEF/TE,%)、达峰容积比(VPEF/VE,%)、达峰容积(VPEF,ml)、达峰时间(TPEF,s)均低于阴道分娩组[TPEF/TE:(21.8±5.8)、(25.4±11.2)比(35.4±8.8),VPEF/VE:(24.4±2.9)、(26.8±8.1)比(33.8±7.3),VPEF:(5.5±1.2)、(6.0±1.1)比(6.7±1.2),TPEF:(0.15±0.10)、(0.14±0.04)比(0.20±0.05),P<0.05];剖宫产组平均吸气流速(MIF,ml/s)、平均呼气流速(MEF,ml/s)较阴道分娩组明显减低[MIF:(35.7±5.1)比(40.1±4.0),MEF:(31.8±6.7)比(36.4±7.0)P<0.05];各组TPEF/TE与VPEF/VE呈高度正相关,r值分别为剖宫产组0.990,阴道分娩组0.992,机械通气组0.933,非机械通气组0.990,P均<0.05。结论在校正胎龄40周时,早产儿潮气呼吸肺功能接近正常同胎龄足月儿,气道发育比足月儿慢,出生早期行机械通气早产儿可能存在肺组织的代偿能力受限和呼吸中枢调节功能不协调。

Pulmonary function study in premature infants at 40 weeks corrected gestational age

Objective To investigate pulmonary function of tidal respiration in premature infants at corrected gestational age of 40 weeks.Methods A total of 40 premature infants were equally allocated into mechanical ventilation and non-mechanical ventilation groups.Various pulmonary function parameters were tested by using tidal respiration method at corrected gestational age of 40 weeks.For normal controls,50 healthy full term infants born at 39-40 weeks gestational age were also recruited and were further divided into C-section control group of 30 and vaginal delivery control group of 20 neonates. The parameters included inspiratory time(TI),expiratory time(TE),respiratory rate(RR),peak tidal expiratory flow(PTEF),time to PTEF(TPEF),ratio of TPEF and total TE(TPEF/TE),expiratory volume at PTEF(VPEF),expiratory volume(VE),ratio of VPEF and total VE(VPEF/VE),mean inspiratory flow rate(MIF),mean expiratory flow rate(MEF).Results The TI(s)and the TE(s)in mechanical ventilation premature group were remarkably longer than the TI&TE times in the vaginaldelivery group and the non-mechanical ventilation premature group[TI:(0.68±0.17)vs.(0.52± 0.06),(0.53±0.11),TE:(0.72±0.15)vs.(0.59±0.13),(0.57±0.09),P<0.05];Patients in the mechanical ventilation premature group had lower respiratory rate(RR,times/min)comparing with patients in the vaginal delivery group and the non-mechanical ventilation premature group[(44.4±7.7) vs.(56.2±10.8),(56.1±9.5),P<0.05)];The TPEF/TE(%),VPEF/VE(%),VPEF(ml)and TPTEF(s)in the two premature infant groups were all lower than in the control vaginal delivery group [TPEF/TE:(21.8±5.8),(25.4±11.2)vs.(35.4±8.8),VPEF/VE:(24.4±2.9),(26.8±8.1) vs.(33.8±7.3),VPEF:(5.5±1.2),(6.0±1.1)vs.(6.7±1.2),TPEF:(0.15±0.10),(0.14± 0.04)vs.(0.20±0.05),P<0.05];The MIF(ml/s)and the MEF(ml/s)in the C-section control group were significantly lower than the values in the vaginal delivery control group[MIF:(35.7±5.1) vs.(40.1±4.0),MEF:(31.8±6.7)vs.(36.4±7.0)P<0.05].The TPEF/TE and the VPEF/VE values revealed strong positive correlation in all four groups with the r=0.990 in the C-section control group,r=0.992 in the vaginal delivery group,r=0.933 in the mechanical ventilation premature group, and r=0.990 in the non-mechanical ventilation premature group.Conclusions Pulmonary function parameters of tidal respiration in premature infants have gradually caught up with the healthy full term infants when the premature infants reach 40 weeks gestational age.The delayed small airway development in the premature patient groups regardless the history of mechanical ventilation.Early mechanical ventilation possibly leads to limited compensation capacity of lung tissue.Premature infants may also have dis-coordination of central respiratory regulation and need further studies with larger sample size.