等量淡水淹溺与海水淹溺对绵羊肺循环血流动力学及呼吸力学影响的随机对照研究

Comparison of pulmonary circulation hemodynamics and respiratory mechanics induced by drowning with equal volume of freshwater and seawater in sheep: a randomized controlled study

目的:比较淡水与海水淹溺对绵羊肺循环血流动力学及呼吸力学的影响。方法:按随机数字表法将健康杂种绵羊分为淡水淹溺组(n=12)和海水淹溺组(n=12),分别经气管插管灌注淡水或海水各30 mL/kg,约5 min灌完。于淹溺前、淹溺即刻及淹溺后30、60、120 min,通过脉搏指示连续心排血量监测技术(PiCCO)监测动物体循环血流动力学参数〔心率(HR)、平均动脉压(MAP)、心排血量(CO)〕,通过呼吸机获得呼吸力学参数〔潮气量(VT)、肺顺应性(Cdyn)、氧合指数(PaO 2/FiO 2)、气道峰压(Ppeak)〕,通过PiCCO和右心漂浮导管(Swan-Ganz导管)测量肺循环血流动力学参数〔肺动脉收缩压(PAS)、肺动脉舒张压(PAD)、肺动脉楔压(PAWP)、血管外肺水(EVLW)〕。于实验终点处死动物,测定呼吸道内残留水量;经苏木素-伊红(HE)染色后观察肺组织病理学改变。结果:①体循环血流动力学:淡水和海水淹溺即刻HR、MAP、CO均较淹溺前明显升高并达峰值,且淡水淹溺组各指标明显高于海水淹溺组〔HR(次/min):170.75±1.87比168.67±2.27,MAP(mmHg,1 mmHg=0.133 kPa):172.92±1.62比159.42±3.18,CO(L/min):13.27±0.71比10.33±0.73,均P<0.05〕。②呼吸力学参数:与淹溺前比较,淡水和海水淹溺即刻PaO 2/FiO 2、VT、Cdyn明显下降,Ppeak明显升高,且海水淹溺较淡水淹溺下降或升高更为显著〔PaO 2/FiO 2(mmHg):37.83±1.99比60.42±5.23,VT(mL):86.25±7.66比278.75±9.67,Cdyn(mL/cmH 2O):8.86±0.33比23.02±0.69,Ppeak(cmH 2O,1 cmH 2O=0.098 kPa):42.17±2.69比17.67±1.15,均P<0.01〕;随着时间的推移,淡水淹溺组PaO 2/FiO 2逐步回升,而海水组呈持续下降趋势。③肺循环血流动力学参数:淡水和海水淹溺即刻PAS、PAD、PAWP均明显高于淹溺前,且淡水淹溺组明显高于海水淹溺组〔PAS(mmHg):34.58±2.87比26.75±1.66,PAD(mmHg):27.25±1.22比16.75±0.87,PAWP(mmHg):27.83±1.85比11.75±1.82,均P<0.01〕;之后淡水淹溺组PAS、PAD逐步下降,而海水淹溺组持续升高;淡水或海水淹溺后PAWP均逐渐下降,分别于淹溺后120 min、淹溺后30 min恢复至淹溺前水平。淡水淹溺后EVLW持续升高,于30 min达峰值,随后减少,至120 min时仍显著高于淹溺前(mL/kg:10.73±1.27比6.67±0.69,P<0.01);海水淹溺后无法测得EVLW。④呼吸道内残留水量:淡水淹溺组呼吸道内残留水量明显少于海水淹溺组(mL:164.33±25.21比557.33±45.23,P<0.01)。⑤HE染色:淡水淹溺组局部肺泡萎缩,部分肺泡间隔断裂,肺泡间隔和肺泡腔可见少许粉染物质沉积;海水淹溺组肺泡扩张,肺泡间隔断裂明显,间质内可见明显出血及水肿液。结论:海水淹溺对动物的呼吸力学及肺循环影响较淡水淹溺动物更为明显,呼吸道内残留水量也明显多于淡水淹溺动物。

Objective To compare the effects of freshwater and seawater drowning on sheep's pulmonary circulation hemodynamics and respiratory mechanics.Methods According to the random number table method,healthy crossbred sheep were divided into freshwater drowning group(n=12)and seawater drowning group(n=12).30 mL/kg of freshwater or seawater was infused respectively through trachea for approximately 5 minutes.Before the drowning,immediately after drowning,and 30,60,120 minutes after drowning,the systemic circulation hemodynamic parameters[heart rate(HR),mean arterial pressure(MAP),cardiac output(CO)]were monitored by pulse indicator continuous cardiac output(PiCCO);the respiratory parameters were obtained through the ventilator,including tidal volume(VT),lung compliance(Cdyn),oxygenation index(PaO2/FiO2),peak airway pressure(Ppeak)];PiCCO and the right heart floating catheter(Swan-Ganz catheter)was used to measure pulmonary hemodynamic parameters[pulmonary systolic pressure(PAS),pulmonary diastolic pressure(PAD),pulmonary artery wedge pressure(PAWP),and extravascular lung water(EVLW)].The animals were sacrificed at the end of the experiment,and the amount of residual water in the respiratory tract was measured;the pathological changes in the lung tissue were observed by hematoxylin-eosin(HE)staining.Results①Systemic circulation hemodynamics:compared with the values before drowning,HR,MAP,and CO at the time of immediately after drowning in both freshwater and seawater were significantly increased and peaked.In addition,all indicators in the freshwater drowning group were significantly higher than those in the seawater drowning group[HR(bpm):170.75±1.87 vs.168.67±2.27,MAP(mmHg,1 mmHg=0.133 kPa):172.92±1.62 vs.159.42±3.18,CO(L/min):13.27±0.71 vs.10.33±0.73,all P<0.05].②Respiratory parameters:compared with values before drowning,PaO2/FiO2,VT,and Cdyn decreased immediately in both freshwater and seawater drowning groups,Ppeak was significantly increased;in addition,the values in the seawater drowning group were decreased or increased more significantly than freshwater drowning group[PaO2/FiO2(mmHg):37.83±1.99 vs.60.42±5.23,VT(mL):86.25±7.66 vs.278.75±9.67,Cdyn(mL/cmH2O):8.86±0.33 vs.23.02±0.69,Ppeak(cmH2O,1 cmH2O=0.098 kPa):42.17±2.69 vs.17.67±1.15,all P<0.01].In addition,PaO2/FiO2 in the freshwater drowning group was gradually increased over time,while the seawater group continued to decline.③Pulmonary circulation hemodynamic parameters:PAS,PAD,PAWP at the time of immediately after drowning in both freshwater and seawater groups were significantly higher than before drowning;in addition,the freshwater drowning group was significantly higher than the seawater drowning group[PAS(mmHg):34.58±2.87 vs.26.75±1.66,PAD(mmHg):27.25±1.22 vs.16.75±0.87,PAWP(mmHg):27.83±1.85 vs.11.75±1.82,all P<0.01].Thereafter,PAS and PAD in the freshwater drowning group gradually decreased,while the parameters in the seawater drown group continued to increase.PAWP gradually decreased after freshwater or seawater drowning,and recovered to pre-drowning levels 120 minutes after drowning and 30 minutes after drowning,respectively.EVLW continued to increase after freshwater drowning,reaching a peak at 30 minutes,and then decreased,until 120 minutes after drowning was still significantly higher than that before drowning(mL/kg:10.73±1.27 vs.7.67±0.69,P<0.01);EVLW could not be measured.④Residual water in the respiratory tract:residual water in the freshwater drowning group was significantly less than that in the seawater drowning group(mL:164.33±25.21 vs.557.33±45.23,P<0.01).⑤HE staining:partial alveolar atrophied in the freshwater drowning group,some alveolar spaces were broken,alveolar spaces and alveolar cavity showed a little powdery substance deposition;it was noted that alveolar expanded in the seawater drowning group,alveolar spaces were broken and bleeding and edema were obvious in the interstitial space.Conclusion The effect of seawater drowning on the respiratory mechanics and pulmonary circulation of animals is more obvious than that of freshwater drowned animals,and the amount of residual water in the respiratory tract is also significantly more than that of freshwater drowned animals.