Coopdech支气管封堵器在围术期的安全应用

目的对比Coopdech支气管封堵器与双腔气管导管用于胸外科手术的安全性。方法选择术中需行单肺通气的胸外科手术患者60例,随机分为两组各30例。A组用Coopdech支气管封堵器,普通气管导管插管固定后从中置入支气管封堵器至目标肺侧支气管;B组常规插入双腔气管导管,用听诊器听诊确定导管位置并固定。观察2组患者(1)单肺通气时肺萎陷质量和外科术野暴露程度.(2)围术期声音嘶哑和咽喉痛的评估。结果两组术侧肺萎陷及手术视野暴露效果优良率差异无统计学意义(P>0.05);双腔支气管组术后声带损伤、声音嘶哑及咽喉疼痛的发生率较封堵器组显着升高(P<0.05)。结论双腔气管导管和封堵支气管导管在胸外科手术行单肺通气中的应用均安全有效,但是应用Coopdech封堵器操作简便且可减少患者术后声带损伤、声音嘶哑及咽喉疼痛的发生率,在其适应证范围内可以优先选用Coopdech支气管封堵器。     

以气道阻(压)力判断Robertshaw双腔导管插管对位305例临床观察

目的 探讨以气道阻力判断Robertshaw双腔支气管导管插管深度及对位正确与否的可行性.方法 随机选择305例剖胸手术患者,静脉快速诱导后,经口腔插入Robertshaw左双腔支气管导管至遇阻力为止.如左、右单肺通气阻力均高,则在右侧单肺通气状态下,逐渐后退双腔支气管导管至气道阻力开始下降,在此导管深度继续后退1.5cm固定导管.如无病理因素,气道阻力在12～20cm H2O范围.观察左、右单肺通气时气道阻力;双肺通气后20min及单肺通气20min分别行动脉血气分析并比较;随机对其中100例应用纤维支气管镜观察导管对位状况.结果 肺部病变患者,患肺通气气道阻力比健侧肺通气时明显增高(P<0.01);食管纵隔病变患者,左肺通气时气道阻力比右肺通气时气道阻力增高(P<0.05);插管后纤维支气管镜检左、右侧导管开口距左肺上叶支气管开口及隆凸距离分别为(1.18±0.28)cm、(2.16±0.34)cm;305例患者双肺通气20min后健侧单肺通气20min后血气分析结果均在正常范围.结论 以气道阻力判断Robertshaw双腔支气管导管插管对位是否正确,方法简捷、实用可行,可供临床参考.     

单肺通气技术的研究现状

单肺通气技术主要有3种：单腔支气管导管通气，双腔支气管导管通气和支气管阻塞导管通气。单腔支气管导管目前已很少采用。双腔支气管导管由于具有插管操作相对耗时较短，常规操作不需要使用纤支镜，肺的萎陷速度较快的优点，为目前单肺通气的首选，但由于其外径较粗，支气管定位复杂，困难气道病人插管成功率低，术后需要长期通气的病人需更换导管等缺点，在一定程度上限制了其使用范围。支气管阻塞导管是一种新型的单肺通气技术，目前主要有四种导管可供临床使用，Univent导管和Cook导管在胸科手术应用较多。Cook导管具有可用于儿童，困难气道插管成功率高，术后不需更换导管及可实现CPAP通气模式等优点，和需要用纤支镜辅助，肺萎陷时间长，容易移位等缺点。双腔管和支气管阻塞导管优势互补，各自在其擅长的领域里发挥作用。     

改良支气管内气囊导管在食管手术中应用

目的:寻找一种简单、安全、有效的方法达到解决食管手术中肺萎陷、单肺通气问题。方法:没汁改良支气管’内气囊导管组,与Robertshaw双腔气管导管组比较,观察术前、麻醉后、单肺通气30min、术后第一天的血气分析、生命体征、气道压改变、术后肺部并发症发生率。结果:在食管手术中应用改良支气管内气囊导管单肺通气,具有对气道损伤,并发症低,效果确切,方法简单、安全,易操作及费用低廉的优点。结论:改良支气管内气囊导管能安全用于食管手术实施单肺通气。     

单肺通气中应用支气管封堵器与双腔支气管导管的比较

目的比较支气管封堵器与双腔支气管导管在胸腔镜下肺大疱切除术中的应用。方法择期80例行胸腔镜下肺大疱切除术患者,随机均分为支气管封堵器组(Ⅰ组)和双腔支气管导管组(Ⅱ组)。Ⅰ组通过支气管封堵器实现单肺通气,Ⅱ组通过插入双腔支气管导管实现单肺通气,所有气管插管均由同一个熟练的麻醉医师完成。观察两组插管时间、定位时间、外科术野暴露程度和术后咽喉疼痛发生情况。结果Ⅰ组插管时间明显短于Ⅱ组(P<0.05),两组定位时间、外科术野暴露程度差异无统计学意义;Ⅰ组术后咽喉痛评分明显低于Ⅱ组(P<0.05)。结论支气管封堵器与双腔支气管导管均能有效应用在胸腔镜下肺大疱切除术患者单肺通气中,应用支气管封堵器可缩短插管时间及减轻患者术后咽喉疼痛。     

纤支镜引导下双腔支气管插管单肺通气的临床效果

开胸手术应用Robershaw双腔支气管插管行单肺通气(OLV),可减少纵膈摆动对循环的影响和手术野的干扰,提高了手术安全性,减少了术后并发症。但仍有约20％病人发生低氧血症[1]。主要是肺泡通气与血流灌注(V/Q)比值下降,肺内分流增加所致,并伴有不同程度的呼吸性酸中毒。本研究拟采用纤支镜引导下双腔支气管导管管端正确定位,     

支气管封堵导管在单肺通气中的应用及术后咽喉炎症反应的研究

目的：探讨应用支气管封堵导管和双腔支气管导管在单肺通气的临床效果的比较。方法选取我院60例胸外科手术治疗需单肺通气患者。随机分为对照组和治疗组,每组各30例。对照组患者采用双腔支气管导管手术通气治疗;治疗组患者采用支气管封堵导管手术通气治疗。记录插管时间、定位时间、肺隔离时间及通过声门尝试次数和和肺萎陷程度、术后声嘶、咽痛发生率。结果与采用双腔支气管导管手术通气组比较,支气管封堵导管组术中肺萎陷良好、术野暴露满意,并且在插管时间、肺隔离时间、定位时间及通过声门尝试次数、术后声嘶、咽痛发生率方面均明显低于对照组患者,两组比较,差异有统计学意义（均P＜0.05）。结论支气管封堵导管手术治疗单肺通气患者的临床疗效明显,手术操作简单、安全,且手术后患者的声音嘶哑、咽喉疼痛等并发症的发生率较低,值得在临床上推广使用。     

结核毁损肺单侧全肺切除的麻醉处理

目的探讨结核毁损肺单侧全肺切除的麻醉处理. 方法 80例结核毁损肺行单侧全肺切除病人,术前肺功能减损轻度者30例(G组),中度者35例(M组),重度者15例(S组).56例行左侧全肺切除:44例使用双腔支气管导管(Carlon管10例、White管20例、左侧Robertshaw管8例、右侧Robertshaw管6例)、右单腔支气管导管7例、气管导管5例.24例行右侧全肺切除:21例使用双腔支气管导管(Carlon管19例、左侧Robertshaw管2例)、左单腔支气管导管2例、气管导管1例.痰量>50 ml/d的16例病人中,采用双腔支气管导管7例、右单腔支气管导管7例、左单腔支气管导管2例. 结果 G组、M组未发生围手术期并发症,S组术后发生急性呼吸衰竭5例(33.33%).痰量>50 ml/d的病人中,2例使用左单腔支气管导管的病人术后均发生健侧支气管病灶播散;而使用双腔支气管导管和右单腔支气管导管未发生结核播散. 结论结核毁损肺重度肺功能减损者,术前FEV1占预计值的百分比<35%,MVV占预计值的百分比<40%,行单侧全肺切除手术要慎重.术前痰量＞50 ml/d的病人,应选择双腔支气管导管或右单腔支气管导管,确保两肺分隔满意,以防止术后健侧支气管病灶播散.     

胸外科单肺通气手术封堵支气管导管与双腔气管导管技术运用的临床效果对比分析

目的探讨胸外科单肺通气手术封堵支气管导管与双腔气管导管技术运用的临床效果。方法选取胸外科单肺通气手术患者46例,依据随机数字表法随机分为观察组和对照组,每组23例。对照组行双腔气管导管技术,观察组行封堵支气管导管技术,比较两组患者通气指标、肺萎陷以及手术视野暴露情况以及并发症发生情况。结果两组患者不同时间段PO_2、PCO_2相比无显著差异,差异均无统计学意义(P0.05)。观察组发生导管位移少于对照组,组间差异具有统计学意义(P0.05)。两组患者肺萎陷以及手术视野暴露情况均为优良,优良率比较差异无统计学意义(P0.05)。观察组患者肺萎陷以及手术视野暴露情况程度优患者多于对照组,组间差异具有统计学意义(P0.05)。观察组患者不良反应发生率低于对照组,差异具备统计学意义(P0.05)。结论胸外科单肺通气手术行封堵支气管导管相比双腔气管导管技术,定位准确,肺通气良好,肺萎陷以及手术视野暴露情况良好,术后并在发生率低,具有重要的临床意义。     

Univent导管在胸腔镜手术气道管理中应用的评价

目的探讨支气管堵塞器Univent导管进行单肺通气气道管理的价值。方法40例因气胸而需要行胸腔镜手术患者按随机数字表随机分为2组:一组为Univent组(U组);一组为双腔气管导管组(D组),使用Robertshaw导管。U组在纤维支气管镜引导下进行插管和定位,D组完成插管后用纤维支气管镜检查确认导管位置。记录2组成功放置导管所需要的时间;摆好体位后,导管移位需要用纤维支气管镜再进行检查和调整位置的次数;肺萎陷的程度;单肺通气期间的气道峰压;单肺通气后30min血气分析的结果。结果成功放置Univent导管的时间长于成功放置双腔气管导管的时间[(6.18±1.26)minvs(3.26±0.82)min,t=8.654,P=0.000]。U组术中导管移位镜检7人次,D组为5人次,差异无显著性(U=187.500,P=0.663)。2组肺萎陷程度差异无显著性(U组肺萎陷程度好15例,中3例,差2例;D组肺萎陷程度好17例,中2例,差1例;U=179.500,P=0.583)。U组的单肺通气气道峰压明显低于D组[(15.3±3.5)cmH2Ovs(21.4±6.6)cmH2O,t=-3.649,P=0.001];...     

左双腔支气管导管管端位置与吸气峰压变化的关系

目的 观测无隆突钩双腔支气管导管(DLT)管端位置与吸气峰压(Ppeak)以及肺顺应性环形状改变的关系，探讨用Ppeak和顺应性环的变化评估DLT管端位置的可行性。方法 拟行右侧剖胸手术的成年患者32例，静脉诱导后插入左Mallinckrodt DLT，吸入氧化亚氮和地氟醚维持麻醉。按纤维支气管镜(FOB)确认DLT管端位置和通气方式将观测过程分为四个阶段：第一阶段(S1)，管端位置正确的双肺通气；第二阶段(S2)，管端位置正确的左侧单肺通气；第三阶段(S3)，管端插入左下支气管(置管过深)的左侧单肺通气；第四阶段(S。)，管端处在左支气管开口(置管偏浅)的左侧单肺通气。每阶段均机械通气15min。结果 回归方程预计插管深度与FOB检查符合者占71．9％。S2时Ppeak值比S1时增加50．8％，肺顺应性(Cdyn)值减少36．2％；S3时Ppeak值比S1时增加87．4％，Cdyn值减少56．8％。PV环曲线斜率向右明显移位，环体显著延长。结论 用无隆突钩DLT行肺隔离，在无FOB定位的条件时，联合应用听诊法、回归方程预计插管深度、动态监测气道峰压和P-V环的变化综合评估，可提高DLT管端的正确到位率。单肺通气的气道峰压超过双肺通气时的1．65倍，且气道峰压超过25cm H2O．应高度怀疑DLT管端发生过深移位。     

Double lumen tube location predicts tube malposition and hypoxaemia during one lung ventilation

Background. Poor positioning of an endobronchial double lumentube (DLT) could affect oxygenation during one lung ventilation(OLV). We set out to relate DLT position to hypoxaemia and DLTmisplacement during OLV. Methods. We recruited 152 ASA physical status I–II patientsabout to have elective thoracic surgery. The trachea was intubatedwith a left-sided DLT. Tube position was assessed by fibre-opticscope and correction was made after patient positioning andduring OLV. If Pa_O2 was less than 10.7 kPa, the DLT positionwas checked and then PEEP, continuous positive airway pressure(CPAP), oxygen insufflation, or two lung ventilation (TLV) weretried. Results. The DLT was found to be misplaced in 49 patients (32%)after patient positioning, and in 38 patients (25%) during OLV.PEEP to the dependent lung, CPAP or apneic oxygen insufflationto the non-dependent lung, or brief periods of TLV, were appliedin 46 patients (30%). Patients who had DLT malposition afterplacing the patient in the lateral position had a greater incidenceof DLT malposition during OLV (59 vs 9%) and also required eachintervention more frequently (57 vs 10%). Patients with DLTmalposition during OLV also required interventions more often(84 vs 12%). Conclusions. Patients who have DLT malposition after placingthe patient in the lateral position had more DLT malpositionduring OLV and hypoxaemia during OLV. Br J Anaesth 2004; 92: 195–201     

Positioning of a double-lumen endobronchial tube without the aid of any instruments: an implication for emergency management

BACKGROUND: Lung isolation and preservation of normal lung are the first lines of therapy in life-threatening massive hemoptysis. If bleeding continues but the side of origin is uncertain, use of a double-lumen tube (DLT) is reasonable. Utilizing a blind method to locate the bronchial cuff of a left-sided DLT without using any instrument, a DLT (Broncho-Cath, Mallinckrodt Medical Ltd., Athlone, Ireland) was successfully positioned without delay in a patient with massive hemoptysis, where auscultation could be misleading or useless and fiberoptic bronchoscope (FOB) was inapplicable. This study was performed to discern whether this blind method could substitute for FOB verification or auscultation in most circumstances where these two methods are unavailable or inapplicable. METHODS: After receiving informed consent and hospital ethics board approval, 58 elective thoracic surgical patients, aged 17 to 67 years, were enrolled in the study and divided into two groups. A conventional method using an FOB was used to locate the left-sided DLT in 29 patients (group 1). In the other 29 patients (group 2), the blind manual method was used. The left-sided DLT was inserted until some resistance was felt, at which time the bronchial cuff was inflated with approximately 2.0 mL of air. While gently holding the pilot with thumb and index finger of the nondominant hand, the DLT was slowly withdrawn until an abrupt decrease of pilot pressure was sensed. At that moment, the bronchial cuff was deflated, and the DLT was advanced approximately 1.5 cm; using an FOB, its position was checked by an independent observer not involved in positioning the DLT. Success was defined as the point when the proximal margin of the carina was within the margin of safety for the DLT, which is defined as the difference between the length of the left main bronchus and the length of the tube between the proximal margin of the left bronchial cuff and the left lumen tip. Postoperative FOB was performed to evaluate bronchial injury. RESULTS: In 26 of 29 patients (group 2), the position of the DLT was bronchoscopically confirmed to be a success. The other three cases were deemed to be too shallow; specifically, the bronchial cuffs were slightly herniated onto the carina (acceptable position). This method was more traumatic than FOB-guided DLT intubation (conventional method) (p = 0.001); however, the most severe damage was erosion. CONCLUSION: This method, which requires no specific instrument and no time-consuming technique, can be taught easily and may be used in a situation where the rapidity of lung isolation or collapse is the key to saving life. We conclude that this blind method can be an alternative to the FOB and/or auscultation for the positioning of DLT in an emergency situation.     

术中双腔支气管插管位置监测方法的评估

目的比较五种监测方法在术中核查双腔支气管插管位置变化的价值。方法选择需行单肺通气的手术患者60例,放置手术体位后同时监测气道阻力、脉搏血氧饱和度(SpO2)、呼气末二氧化碳分压(PETCO2)、流量-容量环和支气管气囊压力,3min后使用纤维支气管镜对双腔支气管插管位置进行判断及调整。结果气道阻力监测的灵敏度为63．64％,特异度为89．80％;PETCO2监测的灵敏度为54．55％,特异度为87．76％;流量-容量环监测的灵敏度为81．82％,特异度为85．71％。结论气道阻力监测、PETCO2监测、流量-容量环监测有助于临床判断双腔支气管插管位置。     

使用可回缩隆突钩放置双腔气管导管：一项前瞻性研究报告

背景双腔气管导管（DLT）的准确放置对于其最佳功能的发挥至关重要。我们利用可回缩隆突钩对标准的左侧DLT盲置法进行改良。本研究旨在明确这种改良法与传统方法相比，是否能够提高首次插管精确定位的成功率。方法对40例拟行左侧DLT的择期全麻手术患者进行了前瞻性随机对照研究。记录使用传统方法（传统方法组，n=20）或者改良法（隆突钩组，n=20）出现位置不正的发生率以及最终放置正确所需要的时间。可回缩隆突钩是经过改良的橡胶弹性探条。采用纤维支气管镜（FOB）证实导管放置位置正确。结果首次放置DLT后，单纯的临床评估发现传统方法组与隆突钩组分别有3例（共20例，15％）和1例（共20例，5％）导管位置不正。随后FOB发现隆突钩组导管位置不正的概率（20例中出现2例，10％）显著低于传统方法组（20例中出现9例，45％）（P=0．03）。两组首次放置DLTs的时间相似（P=0．63），而FOB确认与调整所需的时间在隆突钩组（88．9±35．7秒）显著短于传统方法组（152．3±40．3秒）（P〈0．0001）。结论可回缩隆突钩的使用提高了DLT准确放置的成功率并且缩短了DLT位置调整时间。此外，该方法的安全性与可靠性仍需更大量的研究进行证实。     

Reliability of auscultation in positioning of double-lumen endobronchial tubes

Auscultation is a well-established technique to confirm the position of double-lumen endobronchial tubes (DLTs). However, some authors have recommended that fibreoptic bronchoscopy (FOB) is also indicated. The aims of this study were to determine first if bronchoscopy after blind placement of DLTs improved positioning; and second if preoperative bronchoscopy could detect difficult intubation. Twenty-four patients undergoing aortic or lung surgery were studied. After intubation with a single-lumen tube, an initial FOB was performed by an independent observer to check the airway anatomy. Then, the single-lumen tube was replaced by a DLT using a classical "blind" intubation method. Subsequent FOB was performed first by the independent observer to record the DLT position and next by the investigators for improvement or correction of their positioning under visual control. Fibreoptic bronchoscopy after blind placement of DLTs resulted in repositioning 78% left-sided DLTs and 83% right-sided DLTs. Preoperative bronchoscopy did not always detect an airway abnormality which might lead to difficult positioning of the DLTs. In conclusion, auscultation is an unreliable method of confirming the position of DLTs and should be followed by fibreoptic bronchoscopy.     

单肺通气期潮气量对肺内分流及动脉氧合的影响

目的 研究单肺通气(OLV)时不同潮气量(V_T)对肺内分流及动脉氧合的影响.方法 60例右肺部分切除术患者随机均分为A、B、C三组.全麻后双肺通气(TLV)时V_T均为10 ml/kg,RR均为12次/分,吸呼比(I:E)均为1:2.OLV期间,A组V_T6 ml/kg,RR 20次/分;B组V_T 8 ml/kg,RR 15次/分;C组V_T 10 ml/kg,RR 12次/分;分别于OLV前(T_1)及OLV后10 min(T_2)、20min(T_3)、30 min(T_4)行血气分析,计算肺内分流(Q_S/Q_T),同时监测气道压力并计算肺顺应性(Cdyn).结果 与T_1时比较,T_2～T_4时三组均有PaO_2下降,Q_S/Q_T气道峰压(P_(max))增高,Cdyn下降(P<0.05).与A组比较,B组PaO_2升高(P<0.05).结论 OLV期间采用V_T 8 ml/kg,RR 15次/分能够维持相对较好的PaO_2和CAyn,较小的Q_S/Q_T.     

预期困难气道患者喉罩辅助纤维支气管镜引导气管插管的研究

目的 探讨在预期困难气道患者中采用喉罩辅助纤维支气管镜(fiberoptic bronchoscope,FOB)引导气管插管的应用价值. 方法 择期经口气管插管全身麻醉手术预测困难气道患者24例,ASA Ⅰ或Ⅱ级,入选患者达到以下1种或几种条件为预期困难气道:1.5 cm＜张口度＜3 cm,甲颏间距＜6 cm,头颈活动度＜80°,Mallampati分级Ⅲ、Ⅳ级.采用随机数字表法分为喉罩辅助FOB组(F组)和直接喉镜组(L组),每组12例.F组采用喉罩辅助FOB引导下气管插管;L组在直接喉镜暴露下经口气管插管,3次试插未成功者改行F组方法试插.记录两组患者的气道评估情况、气管插管前(基础值)和插管后3 min的MAP和HR、成功插管的次数及术后的并发症的发生情况. 结果 插管前两组气道评估差异无统计学意义(P＞0.05).与插管前相比,L组患者插管后MAP和HR显著增加,差异有统计学意义(P＜0.05).两组插管后的MAP和HR比较,差异有统计学意义(P＜0.05).F组气管插管一次成功率为75％,3次以内插管合计总成功率为100％;L组气管插管一次成功率为25％,3次以内插管合计总成功率为50％;6例L组患者直接喉镜3次插管不成功后改为喉罩辅助FOB插管,2例1次成功,4例2次成功;F组一次插管成功率和3次插管总成功率均显著高于L组,两组比较差异有统计学意义(P＜0.05).与L组插管时间(161±26)s比较,F组插管时间(81±9)s明显缩短,差异有统计学意义(P＜0.05).F组有2例术后轻度咽喉疼痛,L组有6例术后咽喉疼痛明显和轻度声嘶、2例轻度咽痛. 结论 对术前预期为困难气道的患者采用喉罩辅助FOB引导气管插管可显著提高插管的成功率,降低直接喉镜反复试插引起的术后并发症,具有一定的临床应用价值.     

An update on bronchial blockers during lung separation techniques in adults

Techniques for one-lung ventilation (OLV) can be accomplished in two ways: The first involves the use of a double-lumen endotracheal tube (DLT). The second involves blockade of a mainstem bronchus (bronchial blockers). Bronchial blockade technology is on the rise, and in some specific clinical situations (e.g., management of the difficult airway during OLV or selective lobar blockade) it can offer more as an alternative to achieve OLV in adults. Special emphasis on newer information for the use of Fogarty embolectomy catheter as a bronchial blocker, the torque control blocker Univent, and the wire-guided endobronchial blocker (Arndt blocker) is included. Also this review describes placement, positioning, complications, ventilation modalities, and airflow resistances of all three bronchial blockers. Finally, the bronchial blockers can be used in many cases that require OLV, taking into consideration that bronchial blockers require longer time for placement, assisted suction to expedite lung collapse, and the use of fiberoptic bronchoscopy. The current use of bronchial blockers, supported by scientific evidence, dictates that bronchial blockers should be available in any service that performs lung separation techniques.     

The utility of a double-lumen tube for one-lung ventilation in a variety of noncardiac thoracic surgical procedures.

To determine the utility of one-lung ventilation (OLV) in a variety of noncardiac thoracic surgical procedures, 200 patients were studied to document the ease of double-lumen tube (DLT) placement, associated complications, intraoperative respiratory changes, and methods for managing hypoxic events. Most tubes could be placed, repositioned when necessary, and secured within 12 minutes. By defining tube position with fiberoptic bronchoscopy, auscultatory assessment of placement was found to be incorrect in 38.0% of patients. The tip occluded the respective upper lobe orifice in 40.5% of this subgroup, the endobronchial cuff was at or above the carina in 38.7%, and in the wrong mainstem bronchus in 20.8%. During OLV, PaO2 initially fell to approximately 200 mmHg in most patients but gradually rose during the balance of the operation. Hypoxia (PaO2 less than 80 mmHg) during OLV developed in 28.5% of patients. Preoperative spirometry and arterial blood gases had no predictive value for this complication. Pulse oximetry values between 95% and 100% reliably reflected systemic arterial oxygen saturation. Hypoxia occurring during OLV was successfully reversed in 40.0% of instances by positive end-expiratory pressure (PEEP) to the ventilated lung. The addition of continuous positive airway pressure (CPAP) to the nonventilated lung reversed persistent hypoxia in virtually all cases. There was no difference in oxygenation, carbon dioxide elimination, airway pressures, or intraoperative complications noted between right and left double-lumen tubes. In conclusion, a DLT for OLV can expeditiously and safely be placed. Because auscultation for tube position is unreliable, bronchoscopic assessment of final position should be performed in every instance. Hypoxia during OLV can be detected reliably by pulse oximetry.(ABSTRACT TRUNCATED AT 250 WORDS)