Abstract
目的
评估经鼻高流量预充氧在老年患者全麻气管插管诱导期的安全性研究。
方法
56例非困难气道老年患者,采用随机数字表法分为经鼻高流量吸氧组(HF组)和传统面罩经口鼻吸氧组(M组),28例/组。全麻气管插管诱导给药前预充氧5 min,HF组喉镜检查期间维持给氧,M组通气持续到喉镜检查。观察并记录两组患者基本资料,预充氧前(T1)、预充氧5 min(T2)及插管成功即刻(T3)的超声下胃窦横截面积(CSA)和动脉血气分析指标:PaO2、PaCO2、cSO2,窒息安全时间,插管时间,面罩通气的次数及术后并发症。
结果
两组患者的基本资料差异无统计学意义。预充氧5 min,两组患者的PaO2和cSO2均明显升高,且HF组PaO2较M组明显(F=118.108vs 9.511,P < 0.05),插管成功后PaO2和cSO2均下降,HF组的PaO2值较M组下降缓慢,且仍高于其T1时点,而M组的cSO2值下降显著,低于其T1时点值。HF组窒息安全时间显著高于M组(t=5.305,P < 0.05),且HF组面罩通气次数少于M组(χ2=6.720,P < 0.05)。两组插管后的PaCO2值均增高,但两组比较差异无统计学意义(F=3.138,P > 0.05),其余结果差异也无统计学意义(P > 0.05)。
结论
经鼻高流量吸氧是一种安全简单有效的预充氧方式,与传统的面罩预充氧相比,能提高老年患者的动脉氧分压,延长患者窒息安全时间,可保障老年患者全麻诱导插管时气道管理的安全。
Keywords: 高流量吸氧, 胃窦横截面积, 窒息安全时间, 气道管理
Abstract
Objective
To evaluate the safety of preoxygenation with high-flow nasal oxygenation in elderly patients during induction of general anesthesia with endotracheal intubation.
Methods
Fifty-six elderly patients without difficult airway were randomized equally into high-flow nasal oxygen group (HF group) and conventional mask oxygen group (M group). Preoxygenation was performed for 5 min before induction of general anesthesia and endotracheal intubation. Oxygenation was maintained during laryngoscopy in HF group, and ventilation lasted until laryngoscopy in M group. For all the patients, the general data, cross-sectional area (CSA) of the gastric antrum measured by ultrasonography, arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2) and arterial oxygen saturation (cSO2) were recorded before preoxygenation (T1), at 5 min of preoxygenation (T2) and immediately after intubation (T3). The safety time of asphyxia, intubation time, times of mask ventilation and postoperative complications were compared between the two groups.
Results
The general data were comparable between the two groups. After 5 min of preoxygenation, PaO2 and cSO2 were significantly increased in both groups, and PaO2 was significantly higher in HF group than in M group (F=118.108 vs 9.511, P < 0.05). Both PaO2 and cSO2 decreased after intubation, but PaO2 decreased more slowly in HF group and still remained higher than that at T1; cSO2 decreased significantly in M group to a lower level than that at T1. Compared with those in M group, the patients in HF group showed a significantly longer safety time of asphyxia (t=5.305, P < 0.05) with fewer times of mask ventilation (χ2= 6.720, P < 0.05). PaCO2 increased after intubation in both groups but was comparable between the two groups (F=3.138, P > 0.05).
Conclusion
High-flow nasal oxygen is safe, simple and effective for pre-oxygenation, which, as compared with the conventional oxygen mask, improves arterial oxygen partial pressure and prolongs the safety time of asphyxia to ensure the safety of airway management during induction of general anesthesia in elderly patients with endotracheal intubation.
Keywords: high-flow nasal oxygenation, gastric antrum cross-sectional area, safety time of asphyxia, airway management
随着社会的发展,老年人口逐年增加,保障老年患者围术期的安全性面临着巨大挑战。全麻诱导期预充氧增加机体氧储备是延长气管插管窒息安全时间的重要方法[1, 2]。老年患者口腔周围肌肉萎缩,肺的顺应性及贮备能力相应的降低,完美的密闭鼻面罩正压通气常存在困难,持续正压通气常导致胃胀气,增加胃内容物返流误吸风险[3]。为避免正压通气,临床上常采用传统面罩预充氧,氧流量最大仅到15 L/min,气管插管期间随着窒息时间延长PaO2进行性下降, 增加了低氧血症及严重心血管意外的风险,危及患者生命安全。经鼻高流量吸氧(HFNO)提供最大氧流量可达70 L/min,研究发现诱导期间呼吸暂停时间可达1 h[4],手术期间呼吸暂停时间30 min[5, 6],作为氧疗技术被广泛用于治疗ICU、急诊呼吸衰竭患者和麻醉管理中。但麻醉管理研究中,观察对象为健康志愿者[7, 8],目前有关高流量用于老年患者诱导期预充氧的安全性研究尚未见文献报道。
本研究通过全麻老年患者插管诱导期使用高流量鼻吸氧进行预充氧和呼吸暂停氧合,与使用传统面罩氧合比较,观察是否可获得更长的窒息安全时间,是否会出现胃胀气等风险,评估老年患者麻醉诱导期使用的安全性,为临床替代传统面罩预充氧提供依据。
1. 资料和方法
1.1. 基本资料
选择2020年11月1日~2021年6月1日在本院择期全麻患者68例,性别不限,年龄70.3±4.3岁(最大84岁,最小65岁),BMI 18~25 kg/m2(21.0±2.6 kg/m2),采用随机数字法分为2组:经鼻高流量氧组(HF组)和传统面罩组(M组),HF组3例撤回了同意书,2例动脉血气分析失败,1例改变麻醉方式,M组面罩通气剔除6例,最终每组各纳入28例。纳入标准:需行气管内插管全麻患者;美国麻醉医师学会(ASA)分级Ⅰ~Ⅲ级;改良Mallampati分级Ⅰ~Ⅱ级;年龄 > 65岁;男女不限。排除标准:贫血(Hb < 110 g/ L);术前评估为困难气道;既往困难气道史;严重心肺功能异常;肺部疾病,如肺大泡、气胸等患者;严重鼻塞、鼻出血、近期鼻外伤、近期鼻部手术;颅内压显著升高和颅底骨折者;胃肠道病变手术及既往有胃肠道手术史者。本研究符合医学伦理学标准,并获得广州中医药大学第一附属医院伦理委员会批准[ZYYECK(2020)049],参与研究的病例及其家属均对此项研究内容充分了解,并签署知情同意书。
1.2. 研究方案
1.2.1. 麻醉前准备
所有参与研究的对象均需术前禁食固体食物12 h,禁饮透明液体8 h。术前30 min按研究对象体质量肌注长托宁0.01 mg/kg(成都力思特制药股份有限公司)。入室后建立外周静脉通路,取仰卧位,连接mindray-beneview t5监护仪(深圳迈瑞生物医疗电子股份有限公司)行基本生命体征监测:无创血压、心电图、血氧饱和度,脑电意识深度监测系统(Narcotrend)(广州市鑫驹集团),TOF-WatchSX-多功能肌松监测仪(北京海富达科技有限公司)。局部麻醉和超声引导下放置桡动脉置管。
1.2.2. 预充氧方法
受试者仰卧位于标准枕头。HF组经鼻高流量氧疗仪(广州鲸科医疗科技有限公司)以40 L/min的流量,温度为36 ℃,氧浓度100%,预热后采用治疗模式经鼻吸氧,M组经Datex-Ohmeda麻醉机,以紧密安装的、连接呼吸机的标准麻醉面罩吸氧,氧流量为15 L/min,所有受试者均被指示正常呼吸,预充氧5 min,HF组被指示闭口呼吸。预充氧过程中,采用4个顺序等级评估预充氧时的舒适度,分别为无、轻度、中度、重度,不能耐受者被剔除研究。
1.2.3. 胃窦横面积测量
取患者仰卧位,上腹部偏右侧,使用带有2~5.5 MHz低频探头的华声超声机(深圳华声医疗技术股份有限公司),矢状位通过主动脉平面的确定腹主动脉,肠系膜上动脉(与腹主动脉平行)和肝左叶为标志[9, 10],并取胃蠕动的间歇期以获得标准化的扫描水平。采用描迹法直接测得胃窦横截面积(CSA),均测量3次求平均值降低测量误差。如果超声下看到彗星尾影为胃充气表现[11]。超声下胃窦横截面积的测量由专业培训的同一医生完成(图 1)。
图 1.

仰卧位超声图像
Ultrasound images in the supine position. L: Liver; Ao: Aorta; Sma: Superior mesenteric artery; A: Gastric antrum. The arrow in b indicates the aerated sign of the gastric antrum.
1.2.4. 诱导方法
静脉给予舒芬太尼0.3 μg/kg(宜昌人察并记录Narcotrend脑电意识深度监测系统的NT值由福药业有限责任公司)和丙泊酚1.5~2.5 mg/kg(广东A降到D0或以下,肌松监测仪TOF值为0时,采用可视嘉博制药有限公司),意识消失后给予顺式阿曲库铵喉镜(中国浙江UE医疗公司)经口可视下将加强钢丝0.15 mg/kg(浙江仙琚制药股份有限公司),3 min后,观ParkerFlex-TipⓇ气管导管(中国驼人医疗公司)插入声门,连接麻醉机行机械通气,监护仪显示呼气末二氧化碳(ETCO2)为气管内插管成功。诱导过程麻醉药物的剂量及插管操作均由主治及以上职称的麻醉医生决定并完成,由另一助手在预充氧前(T1),预充氧5 min(T2),插管成功即刻(T3)抽取动脉血1 mL,使用西门子epoc干式手持式血气分析仪(上海涵飞医疗器械有限公司)测动脉血气分析。
1.2.5. 安全保障
插管时间定为从喉镜放入口角到能看到呼气末二氧化碳波形。窒息安全时间定为从意识消失到插管成功的时间或脉搏氧饱和度(SpO2)下降至95%的时间。麻醉诱导期间,意识消失SpO2下降至95%,如果肌肉松弛已满足插管条件则行气管插管,确认插管成功后,立即行机械通气;如果不满足插管条件或喉镜检查过程中SpO2至95%,并不能顺利插管时,SpO2有继续下降风险则面罩加压通气,使SpO2上升至100%。所有未预见性困难气道,最多有3次气管插管的机会,否则将置入喉罩或等待患者苏醒。如患者术中心率 < 50次/min,给予阿托品0.5 mg处理;收缩压 < 90 mmHg或下降幅度>30%,给予去氧肾上腺素等血管活性药物处理。
1.3. 观察及记录指标
基本资料:性别、年龄、身高、体质量、BMI、平均动脉压、心率、SpO2,ASA分级,合并其他疾病,术前血细胞比容(HCT);预充氧前(T1),预充氧5 min(T2),插管成功即刻(T3)测动脉血气分析,记录PaO2,PaCO2,cSO2,仰卧位同一体表的CSA,有无胃充气征;窒息安全时间和插管时间;预充氧期间舒适度,面罩通气的例数,插管管期并发症如心律失常、口鼻腔出血,牙齿损伤等。
1.4. 统计学分析
采用SPSS 23.0软件进行统计处理,计量资料采用均数±标准差表示,不同时点指标采用重复测量的统计学方法,采用Mauchly方法检验是否满足球形假设。当资料满足球形假设时,可直接进行一元方差分析;不满足时,应以多元方差分析结果为准;两组变量采用两独立样本t检验,等级资料组间比较采用秩和检验。所有检验均为双侧检验,P < 0.05时认为差异具有统计学意义。所有实验都是独立重复3次。
2. 结果
2.1. 病例基本资料
两组患者基本资料差异无统计学意义(表 1,P> 0.05)
表 1.
两组患者基本资料比较
Comparison of the general data between the two groups of patients (Mean±SD)
| Variables | HF group (n=28) | M group (n=28) | Statistic | P |
| HF: High-flow nasal oxygenation; M: Traditional mask; BMI: Body Mass Index; MAP: Mean arterial pressure; HR: Heart rate; HCT: Haematocrit; SpO2: Peripheral capillary oxygen saturation; ASA: Acoustical society of america. | ||||
| Gender (male/female, n) | 13/15 | 14/14 | 0.072 | 0.789 |
| Age (year) | 71.0±4.4 | 69.5±4.2 | 1.275 | 0.208 |
| Height (cm) | 162.9±6.5 | 161.4±8.1 | 0.766 | 0.447 |
| Weight (kg) | 54.8±6.4 | 55.4±7.2 | -0.374 | 0.710 |
| BMI (kg/m2) | 20.7±2.7 | 21.3±2.5 | -0.836 | 0.407 |
| MAP (mmHg) | 92.1±7.1 | 93.8±7.0 | -0.914 | 0.365 |
| HR (bpm) | 80.0±11.3 | 76.0±9.6 | 1.413 | 0.163 |
| HCT (%) | 38.0±3.2 | 38.3±4.2 | -0.284 | 0.777 |
| SpO2 (%) | 97.9±1.5 | 98.2±1.5 | -0.728 | 0.470 |
| ASA grade (n, %) | 0.327 | 0.849 | ||
| I | 8 (28.6) | 7 (25.0) | 0.091 | 0.763 |
| II | 16 (57.1) | 18 (64.3) | 0.299 | 0.584 |
| III | 4 (14.3) | 3 (10.7) | 0.163 | 0.686 |
| Comorbidity (n, %) | ||||
| Hypertension | 11 (39.3) | 10 (35.7) | 0.076 | 0.783 |
| Diabetes | 5 (17.9) | 4 (14.3) | 0.132 | 0.716 |
| Angiocardiopathy | 12 (42.9) | 7 (25.0) | 1.991 | 0.158 |
| Respiratory Disease | 10 (35.7) | 8 (28.6) | 0.327 | 0.567 |
2.2. 患者不同时间点的动脉血气分析
表 2显示,两组患者预充氧5 min PaO2和cSO2迅速升高,与预充氧前比较,差异均具有统计学意义(P < 0.05),插管成功后PaO2和cSO2,两组值下降,PaO2与T2时点比较差异具有统计学意义(P < 0.05),HF组较M组下降缓慢,T3时点的PaO2与T1时点比较差异具有统计学意义(P < 0.05),而M组cSO2下降明显,与T1时点比较差异具有统计学意义(P < 0.05),插管成功后,两组PaCO2均明显升高,且与T1时点和T2时点相比差异具有统计学意义,其余指标比较,差异无统计学意义(P>0.05)。组间比较:PaO2和cSO2两组比较差异有统计意义(F=118.108,P < 0.05;F=9.511,P < 0.05,而PaCO2和CSA两组比较差异无统计学意义(F=3.138,P>0.05;F=0.022,P>0.05)
表 2.
两组患者不同时点的动脉血气分析:PaO2, PaCO2, cSO2, CSA的比较
Arterial blood gas analysis at different time points between the two groups (Mean±SD)
| Variable | HF group (n=28) | M group (n=28) | Statistic | P | |||||
| T1 | T2 | T3 | T1 | T2 | T3 | ||||
| HF: High-flow nasal oxygenation; M: Traditional mask; PaO2: Arterial partial pressure of oxygen; PaCO2: Arterial partial pressure of carbon dioxide; cSO2: Arterial oxygen saturation; CSA: Cross sectional area; aP < 0.05 vs T1 time point, bP < 0.05 vs T2 time point, cP < 0.05 vs T3, d, eP < 0.05 vs M group. | |||||||||
| PaO2 | 77.7±6.4 | 546.6±79.0a | 295.0±130.3bc | 80.9±5.8 | 386.2±38.4a | 85.8±54.1c | 118.108 | 0.000d | |
| PaCO2 | 40.9±9.4 | 40.8±5.5 | 60.7±7.0bc | 38.0±3.6 | 38.6±3.6 | 58.4±7.9bc | 3.138 | 0.082 | |
| cSO2 | 95.3±1.3 | 100.0±0.0a | 96.9±6.2c | 96.0±1.3 | 100.0±0.0a | 90.4±7.0bc | 9.511 | 0.003e | |
| CSA | 3.3±0.4 | 3.4±0.4 | 3.4±0.5 | 3.3±0.5 | 3.4±0.6 | 3.4±0.5 | 0.022 | 0.883 | |
2.3. 两组患者插管时间、窒息安全时间
两组插管时间结果相比差异无统计学意义(P > 0.05),而窒息安全时间HF组较M组延长,差异具有统计学意义(t=0.5.305,P < 0.05,表 3)。
表 3.
两组患者的插管时间及窒息安全时间的比较
Comparison of intubation time and safety time of asphyxia between the two groups (Mean±SD)
| Variables | HF group (n=28) | M group (n=28) | Statistic | P |
| Intubation time | 68.4±15.8 | 65.9±17.6 | 0.551 | 0.584 |
| Safety time of asphyxia | 282.1±44.2 | 218.6±45.4 | 5.305 | < 0.001 |
| Mask ventilation | 0 | 6 | 6.72 | 0.010 |
| Gastric inflation | 0 | 1 | 1.018 | 0.313 |
2.4. 两组患者预充氧期间舒适度及不良事件的比较
HF组有3.6%患者有重度的不适,10.7%的患者有中度不适,M组未出现重度的不适患者,仅有3.6%的患者有中度不适,我们给予再次宣教指导其正常呼吸,均完成预充氧,两组差异无统计学意义(表 4,P>0.05)。
表 4.
两组患者预充氧期间舒适度的比较
Comparison of comfort degree during preoxygenation between two groups
| Discomfort level | HF group (n=28) | M group (n=28) | Statistic | P |
| No discomfort | 6 (21.4) | 8 (28.6) | 0.381 | 0.537 |
| Mild discomfort | 18 (64.3) | 19 (67.9) | 0.080 | 0.778 |
| Moderate discomfort | 3 (10.7) | 1 (3.6) | 1.077 | 0.299 |
| Severe discomfort | 1 (3.6) | 0 (0) | 1.018 | 0.313 |
2.5. 不良事件的描述
手术前1 d,主麻医生对纳入研究患者行气道评估,包括Mallampati评分,张口度、头颈活动度,甲颏距离,及口腔牙齿情况等,均为非困难气道。HF组有2例患者,通过调整气管导管引导芯的曲度,第2次顺利完成气管插管术,SpO2均维持在100%,窒息安全时间长达360 s,期间未行面罩正压通气。而M组有6例,意识消失后不满足插管条件,SpO2下降至95%,需面罩加压给氧升高SpO2至100%,其中有2例插管过程中SpO2再次下降,最低至90%,余均顺利插管。M组有1例在2次加压给氧后观察到彗星尾影,表现为胃充气征,HF组未发现有胃充气征。两组患者术后24 h均未有鼻出血、牙齿损伤、心律失常等气管插管相关并发症。
3. 讨论
经皮氧监测是临床上常用一种无创动脉血氧分压监测技术,研究表明SpO2 > 90%,足够保证肺泡氧合,常作为全麻诱导期气管插管的安全时限[12, 13]。本研究对象为老年患者,储备能力下降,常伴有心肺疾病,对缺氧耐受差,根据预试验统计学分析及相关文献参考,所有患者采取SpO2降至95%或呼吸窒息时间8 min[14]为保证患者安全的时限。
本研究采用HFNO(流量40 L/min)和传统面罩(流量15 L/min)两种不同方式预充氧,预充氧前,预充氧5 min后及插管成功即刻抽取动脉血行血气分析,观察两组患者PaO2和cSO2的氧合变化,结果发现预充氧5 min后PaO2和cSO2均升高且HF组较M组的上升的更高,可迅速提升血氧含量。两组的插管时间相近,差异无统计学意义(t=0.551,P=0.584 > 0.05),成功插管即刻测动脉血气,结果发现两组的PaO2和cSO2均下降,然HF组PaO2值仍高于预充氧前PaO2值,而M组cSO2值低于预充氧前,且M组有6例窒息安全时间不足3 min,需面罩加压给氧提高SpO2,且插管过程又有2次SpO2下降,充分说明了老年患者耐缺氧能力下降,极易发生低氧血症。HF组窒息安全时间长于M组,有2例患者为未预见性困难气道,经2次喉镜检查和调整气管导管弯曲度顺利气管插管,窒息安全时间长达360 s,SpO2仍保持100%,体现HF组在预充氧后,可安全保障老年患者气管插管的窒息时限。HFNO在喉镜检查气管插管过程中可继续给氧,冲洗咽喉,声门下等气道,促进窒息氧合,延长窒息安全时间,而M组则需要移开面罩。当患者为未预见性困难气道时,HFNO可提高预充氧合和窒息氧合,延长安全插管时间,充分体现了HFNO的优势。
HFNO较传统面罩吸氧优势还体现在可提供更高的氧流量,通过冲洗呼吸道死腔量降低二氧化碳蓄积,增加气道压力和呼气末肺容积,能够持续向呼吸暂停患者输送氧气。有研究表明HFNO在呼吸暂停期间动脉二氧化碳水平减少约50%[15-17]。本研究两组患者预充氧5 min后,PaCO2未有明显变化,成功插管后PaCO2均显著增高,且两组之间比较差异并无统计学意义,并未发现HF组的PaCO2下降,这与Spence等研究结果不一致[18]。为还原临床工作,本研究患者意识消失后,头部自然摆放,未能很好保持“嗅花位”,气道未能完全开放,致使高流量氧冲洗效果下降,CO2蓄积,PaCO2升高。是否将患者头部处于嗅花位或托起下颌,改善二氧化碳蓄积,值得进一步研究。
围手术期胃内容物反流误吸,是一种可导致严重发病率和死亡率的并发症[19, 20]。经鼻输送高流量氧是否因增加气道压力而引起胃胀,增加反流误吸的风险[21],越来越受到关注。胃内容物(液体、固体或空气)的性质可通过胃部超声显像体现,胃内容物容积与胃窦横截面积呈正相关[10, 22]。因此,我们对两组患者行仰卧位同一体表位置的胃窦横截面积测量评估胃内容积及胃胀气,结果显示HF组预充氧前后及成功插管后的胃窦横截面积并未发生改变,且未看到胃充气彗星影征,说明本研究40 L/min的高流量鼻氧在全麻预充氧不会导致胃充气,这与McLellan和Sud等[23, 24]结果一致。目前临床工作中,常采用小潮气量快频率、低气道压面罩通气的方法避免胃充气及反流误吸,但研究发现仍存在胃胀气风险尤其当遇到困难气道,需反复面罩通气改善氧合,增加了麻醉诱导期并发症的发生。本研究过程在M组在面罩通气2次后发现1例胃充气表现,幸运的是两组均未出现反流误吸,鼻出血等并发症。
本研究的局限性:首先,在预充氧方式和超声胃窦测量方面均未能进行盲法,增加了偏倚的风险。其次,小样本量降低了统计能力,单中心设计和同质研究的总体限制了概括性。因为研究表明肥胖患者及儿童存在低储备和高代谢状态,已被认为是低氧血症的高危人群[25],且可能并存气道困难,本研究为未纳入肥胖(BMI > 30 kg/m2)的老年患者,值得我们下一步研究。
综上所述,HFNO可安全应用于非困难气道的老年患者在气管内插管全麻诱导前预充氧,避免正压通气,可提高窒息安全时间,以维持足够的氧水平,可替代传统面罩预氧合,为临床工作中气道管理提供—可靠保障。
Biography
蔡清香,硕士,E-mail: xiang2007mz@126.com
Funding Statement
广东省科技厅社会发展项目(2017ZC0155)
Contributor Information
蔡 清香 (Qingxiang CAI), Email: xiang2007mz@126.com.
张 广防 (Guangfang ZHANG), Email: abcde521mz@163.com.
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