非小细胞肺癌合并2型糖尿病患者运动耐量及通气效率的临床特点

目的 探讨非小细胞肺癌(NSCLC)合并2型糖尿病(T2DM)患者运动耐量和通气效率的特点。 方法 根据胸外科数据库和电子病例资料筛选出合并T2DM的NSCLC患者(48例),使用倾向性评分法在病例中1∶1匹配出单纯肺癌患者(48例),据此分为合并T2DM组及未合并T2DM组,且所有患者行肺切除术前完成心肺运动试验(CPET),另择同期行CPET的健康体检者作为健康对照组(24例),对CPET结果进行分析,包括静态肺功能指标、CPET核心指标、运动耐量及心率恢复指标和通气效率及气体交换指标。 结果 与健康对照组相比,合并T2DM和未合并T2DM组的峰值摄氧量(VO2peak)、无氧阈(AT)及峰值氧脉搏(peak O2pulse) 均降低,二氧化碳通气当量斜率(VE/VCO2slope)及最低值(VE/VCO2nadir)均上升(P<0.01);与未合并T2DM组相比,合并T2DM组VO2peak、峰值公斤摄氧量(peak VO2/kg)及最大功率(WRpeak)均降低,VE/VCO2slope、VE/VCO2nadir均升高(P<0.05)。与健康对照组相比,在AT和峰值运动时,2组NSCLC患者的VO2和VCO2均下降(P<0.05),且峰值时合并T2DM组较未合并T2DM组更低(P<0.05)。热身和AT时,2组NSCLC患者的HR值较健康对照组高,与健康对照组和未合并T2DM组相比,合并T2DM组在恢复期1～3 min内心率下降减慢(P<0.05)。与健康对照组相比,AT和峰值时2组NSCLC患者的二氧化碳通气当量(VE/VCO2)上升(P<0.05);在热身和AT时,2组NSCLC患者的潮气末二氧化碳分压(PETCO2)均下降(P<0.05),合并T2DM组在峰值时低于健康对照组(P<0.05)。与健康对照组和未合并T2DM组相比,合并T2DM组的第1秒用力呼气容积(FEV1)、每分钟最大通气量(MVV)、呼气流量峰值(PEF)及其绝对值占预计值百分比(FEV1%,MVV%,PEF%)、用力肺活量绝对值占预计值的百分比(FVC%)和第1秒用力呼气容积占用力肺活量百分比(FEV1/FVC)均下降(P<0.05),且未合并T2DM组较健康对照组均降低,但差异无统计学意义（P>0.05）。 结论 与健康人相比,NSCLC合并T2DM的运动耐量及运动时通气效率均下降,未合并T2DM组的运动耐量下降,通气效率大致正常;CPET可为NSCLC合并T2DM患者肺切除术围手术期的风险评估提供依据。     

心肌缺血患者心肺运动试验特点

目的:研究心肺运动试验(CPET)相关指标在心肌缺血患者的变化特点。方法:52例胸痛患者,分别行CPET、99mTc-MIBI心肌灌注显像检查及心脏彩色多普勒检查。根据心肌灌注显像检查结果分为心肌缺血组及非缺血组。比较两组患者之间CPET相关指标如每公斤体重峰摄氧量(VO2peak/kg)、峰摄氧量(VO2peak)、峰氧脉搏(VO2peak/HR)、最大呼吸频率(RR)、氧斜率(O2slope)、呼吸储备(BR)、最大心率(HR)、心率储备(HRreserve)和无氧阈(AT)、无氧阈时氧气通气当量(VE/VO2@AT)、无氧阈时二氧化碳通气当量(VE/VCO2@AT)、无氧阈时氧脉搏(VO2/HR@AT)以及彩色多普勒检查心脏二尖瓣口血流舒张早期峰值速度(E)与舒张晚期峰值速度(A)的比值(E/A值)和左室射血分数(EF值)。结果:两组患者之间年龄、性别构成、体重指数、E/A值及EF值均无统计学差异。心肌缺血组VO2peak/kg、VO2peak、VO2peak/HR、HR、AT、VO2/HR@AT低于非缺血组,差异具有统计学意义。结论:心肌缺血患者VO2peak/kg、VO2peak、VO2peak/HR、AT和VO2/HR@AT等心肺运动指标较非心肌缺血患者降低。     

吸入沙美特罗替卡松对中重度慢性阻塞性肺疾病患者运动耐力的影响

目的 通过对吸入沙美特罗替卡松粉(SFC)治疗中重度慢性阻塞性肺疾病(COPD)患者进行研究,探讨吸入糖皮质激素联合长效β2受体激动剂对中重度COPD静息肺功能和运动耐力的影响.方法 选择稳定期的中重度COPD患者53例,随机分为治疗组与对照组.治疗组吸入SFC(每泡含沙美特罗50μg,丙酸氟替卡松250 μg),每日2次,每次1喷,对照组给予一般治疗.24周后,观察患者肺功能(PFT)及心肺运动试验(CPET)各项生理参数指标的变化.结果 试验开始时,治疗组与对照组的PFT参数与CPET参数相比较,无统计学差异.SFC治疗24周后,治疗组的静态肺功能指标显示,患者用力肺活量(FVC)由治疗前(2.5±0.6)L增加至(3.0±0.5)L,第一秒用力呼气量(FEV1)由治疗前(1.1.4±0.4)L增加至(1.3±0.2)L,深吸气量(IC)由治疗前(1.9±O.4)L增加至(2.2±0.5)L,胸廓内气量(ITGV)由治疗前(5.8±0.6)L减低至(5.1±0.7)L,残气量(RV)由治疗前(4.8±0.7)L减低至(4.0±0.8)L,肺总量(TLC)由治疗前(7.6±1.1)L减低至(7.3±1.0)L,差异均有统计学意义;CPET发现,峰值功率(Peak WR)由治疗前(86.2±13.5)watt增加至(91.2±15.1)watt,稍有改善,但无显著的统计学差异;峰值摄氧量(Peak VO2)由治疗前(1341.2±261.4)ml/min增加至(1796.0±282.5)ml/min,峰值公斤摄氧量(Peak VO2/kg)由治疗前(20.7 ±5.0)ml·min-1·kg-1增加至(23.5±4.4)ml·min-1·ks-1,Peak VCO2由治疗前(1671.4±254.3)ml/min增加至(1995.1±241.7)ml/min,峰值氧脉搏(Peak O2 pulse)由治疗前(7.5±2.3)ml/beat增加至(10.9±2.7)ml/beat,峰值通气量(Peak VE)由治疗前(31.2±10.2)L/min增加至(37.2±9.2)L/min,死腔/潮气量(VD/VT)由治疗前(39.4±7.0)%减低至(32.4±6.1)%,二氧化碳通气当量最低值(Lowest VE/VCO2)由治疗前32.5±3.2减低至28.8±2.9;PET中IC改善值与CPET中Peak VO2、Peak VO2/ks、Peak VE、VD/VT、Lowest VE/VCO2:等的改善值有良好的相关性,而FEV1的改善值与上述CPET的参数改善无显著相关.对照组用药前后,患者PFT及CPET各参数无明显的变化.结论 中重度COPD患者的运动耐力显著减低,长期使用SFC后,其气流受限的改善程度有限,峰值运动功率仅有轻微改善,但患者的静息及运动时的肺过度充气状态明显减轻,通气/血流匹配状况明显好转,通气效率得到显著改善,从而提高运动耐受能力.     

高血压患者运动耐量的研究

目的通过对高血压患者心肺功能的评定,探讨高血压患者运动耐量的变化。方法选择符合入选标准的患者70例,按有无高血压分为高血压组(n=40),非高血压组(n=30),进行心肺运动试验,测定并比较两组在达最大摄氧量(VO2max)和无氧阈(AT)时的摄氧量(VO2)、二氧化碳排出量(VCO2),计算相应的代谢当量(METs)、每千克体质量摄氧量(VO2/kg);记录并比较两组的心率、血压和运动时间,计算最大心率血压乘积(RPP max)。结果高血压组与非高血压组各项指标的比较:运动时间(5.9±1.6)min vs(7.2±1.5)min,VO2max/kg(21.7±4.4)ml.min-1.kg-1vs(24.8±4.2)ml.min-1.kg-1,METs max(6.2±1.3)vs(7.1±1.2),最大心率(HR max)(141.6±14.9)次/min vs(156.5±29.1)次/min,RPP max(25.1±4.6)×103vs(28.1±6.7)×103,VO2AT/kg(19.2±3.5)ml.min-1.kg-1vs(21.5±3.7)ml.min-1.kg-1,METs AT 5....     

运动训练对低肺功能肺癌患者手术耐受性的影响

目的:探讨术前短期中高强度下肢运动训练对低肺功能肺癌患者肺切除手术耐受性的影响.方法:采用随机单盲设计,将61例可切除肺癌合并重度慢性阻塞性肺病患者,根据美国胸科医师协会肺切除术前评估指南分为可手术A组和不可手术B组;A组再随机分为A1亚组(训练亚组)和A2亚组(对照组).A1亚组和B组术前予每周5次、连续2周、强度达60％-80％峰值氧摄量VO2max的踏车运动训练,辅以胸腹联合缩唇呼吸训练.比较训练前后静态肺功能和运动心肺功能的变化;训练后重新评估B组手术风险;比较训练Al亚组和对照A2组肺切除术后并发症情况.结果:训练后,在A1亚组,心肺功能指标:肺一氧化碳弥散量DLCO(P=0.003)、VO2max(P＜0.001)、无氧阈AT(P=0.008)、氧脉VO2max/HR(P＜0.001)较训练前显著改善;在B组,心肺功能指标:用力肺活量FVC(P＜0.001)、分钟最大通气量MVV (P=0.001)、DL.CO (P＜0.001)、最大功率W(P=0.004)、VO2max (P＜0.001)、AT(P=0.002)、VO2max/HR (P=0.00l)、峰值通气量VEmax(P=0.015)、无氧阈时CO2通气当量VE/VCO2@AT (P=0.003)和运动后经皮血氧饱和度SPO2％(P=0.002)均较训练前显著改善;B组中59％(10/17)患者达手术标准;训练A1亚组较对照A2组,肺切除术后氧疗时间(P=0.04)、机械通气时间(P=0.036)和住院天数(P=0.025)均显著缩短.结论:术前短期中高强度下肢运动训练能有效、可行地提高低肺功能肺癌患者心肺功能适应性,有助于肺切除术后康复.     

呼吸锻炼对肺癌术后患者肺功能和生活质量的影响

目的观察长期的呼吸锻炼对肺癌术后患者肺功能及健康质量改善情况的影响。方法符合入选标准的肺叶切除术后的患者纳入研究,根据知情同意和自愿原则,分成干预组(n=41)和对照组(n=42)。干预组于术后1个月,每日9点、14点、19点3个时间段进行呼吸锻炼,持续1h·次-1;呼吸频率6次·min-1,即单次吸气、屏气、呼气的过程,总时间控制在10s。观察2组术前及术后1、6、12个月第一秒用力肺活量(FEV1)、用力肺活量(FVC)和FEV1/FVC比值,摄氧量最高值(VO2peak)和健康质量评估量表(SF-36)的变化。结果经过1年的术后随访,通过干预组和对照组的比较,认为呼吸锻炼能有效纠正手术所造成的肺功能障碍、改善肺功能状态(FEV1,FVC和FEV1/FVC,P<0.05),提高了摄氧量最高值(VO2 peak,P<0.001)。同时可能因为肺功能的改善,患者的健康质量也得到了显著的提高(P<0.05)。结论长期的呼吸锻炼简单易行,可有效改善肺癌患者术后肺功能及健康质量。 更多还原     

五禽戏锻炼对出院过渡期慢性阻塞性肺疾病患者肺功能 及运动耐量的影响

目的:观察五禽戏锻炼对出院过渡期慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)患者肺功能及运动耐量的临床改善效果。方法:选择2015年1至12月在佛山市南海区第四人民医院治疗随访的COPD患者,随机分为五禽戏组和对照组,对照组给予常规的随访管理及运动锻炼,五禽戏组在此基础上实施五禽戏锻炼,锻炼共持续3个月,比较两组干预前后的肺功能及运动耐量。结果:干预后五禽戏组的第1秒用力呼气容积(forced expiratory volume in one second,FEV_1)、第1秒用力呼气容积/用力肺活量(FEV_1/forced vital capacity,FEV_1/FVC)、第1秒用力呼气容积占预计值百分比(FEV_1%pred)依次为1.55 L,55.31%和55.08%,明显高于干预前的1.33 L,40.17%和43.03%及干预后对照组的1.25 L,43.55%和44.61%,差异均具有统计学意义(P0.05);在运动耐量方面,干预后五禽戏组的6 min步行距离(6 min walk distance,6MWD)、达到无氧阈(anaerobic threshold,AT)时的运动时间及最大摄氧量依次为417.56 m,418.25 s及19.53 m L/(min·kg),明显高于干预前的332.67 m,337.14 s和15.53 m L/(min·kg)及干预后对照组的350.78 m,328.03 s和14.44 m L/(min·kg),差异均具有统计学意义(P0.05);同时结果还显示,对照组在FEV_1/FVC及6MWD的改善差异也具有统计学意义(P0.05)。结论:实施五禽戏锻炼有利于改善出院过渡期COPD患者的运动耐量及肺功能状态,对于提升其康复效果具有积极的推动作用。     

稳定期慢性阻塞性肺疾病患者肺康复下肢运动训练处方的研究

目的 观察下肢运动训练对稳定期慢性阻塞性肺疾病(COPD)患者的肺功能、运动耐力及运动心肺功能的影响,同时对肺康复中运动训练的方式、强度、频度等的设定进行探索,为制定出适合中国COPD患者的肺康复运动处方提供依据.方法 选择稳定期COPD患者29例,随机分为对照组10例,训练组19例.对照组接受常规的内科药物治疗,维持日常活动量;训练组除接受常规内科药物治疗外,还接受为期8周,每周2次,每次40 min的下肢运动训练.训练方式采用下肢功率踏车训练,初始训练强度为70%最大运动负荷(WRmax),当患者能够连续2次完成预设的训练强度和时间时,以10% WRmax的梯度增加训练负荷作为下一个训练强度直至8周末.结果 经过8周的下肢运动训练,训练组患者的运动耐力指标6 min步行距离(6MWD)较训练前平均增加(45.3±27.3)m(P<0.05),WRmax增加(10.8±6.9)watt,峰值摄氧量(VO2 Peak)增加(158.9±137.3)ml/min,VO2/kg增加(2.6±2.6)ml·min-1·kg-1,无氧阈(AT)增加(93.1±91.2)ml/min,差值均具有统计学意义(P<0.01);通气指标二氧化碳生成量(VCO2)增加(102.6±177.9)ml/min(P<0.05),分钟通气量(VE)增加(5.3±4.9)L/min(P<0.01);心功能指标最大氧脉(O2 pulse)和最大心率(HRmax)较对照组显著提高(P<0.05);静态肺功能指标于训练前后未见明显变化.同时,对照组上述各组指标在8周前后均无明显变化.结论 下肢高强度运动训练可以提高稳定期COPD患者的运动耐力,改善患者在运动中的通气功能和心功能,但是对静态肺功能无明显改善作用;下肢功率踏车训练,为期8周,每周2次,每次40 min,以70% WRmax作为起始训练强度,在能连续2次完成规定的训练强度和时间的前提下,以10% WRmax为梯度递增训练强度直至8周末,这一肺康复下肢运动训练处方对于中重度COPD患者来说安全、可行,值得推广.     

摄氧效率斜率评价慢性阻塞性肺疾病患者心肺功能的价值

目的探讨摄氧效率斜率(OUES)评价慢性阻塞性肺疾病(COPD)患者心肺功能的价值。方法对54 例肺功能Ⅱ~Ⅳ级的稳定期COPD患者进行运动心肺功能的评价,采用症状限制性Steep 分级平板运动方案,同时测定摄氧量(VO2)、二氧化碳排出量(VCO2)、峰值摄氧量(VO2peak)、每分通气量(VE)、呼吸气体交换率(RER)。采用对数曲线拟合的方法,分析递增负荷运动试验中VO2与VE之间的关系,建立回归方程VO2=algVE+b,计算摄氧效率斜率(OUES),即a。同时测定无氧阈(VAT)。结果OUES与VO2peak呈显著正相关(均P<0.001)。75% OUES、90% OUES、100% OUES三者均值无显著性差异(F=0.239, P=0.830)。结论OUES可以反映COPD患者运动心肺功能,75% OUES可以作为亚极量运动水平心肺功能的评价指标。     

四肢联动在脑卒中患者心肺适能评估中运用的可行性

目的:分析四肢联动在脑卒中患者心肺适能评估中运用的可行性,探索评估脑卒中患者心肺功能的适宜设备。方法:19位脑卒中患者均先后使用功率自行车和四肢联动两种设备进行两次症状限制性最大递增心肺运动试验,并用配对t检验分析两次试验获得的峰值摄氧量(VO2peak)以及峰值心率(HRpeak)之间的差异,并采用Pearson相关系数检验它们的相关性。结果:两次试验获得的VO2peak以及HR peak存在高度相关(分别r=0.95和r=0.96),使用四肢联动获得的VO2peak明显高于功率自行车[(14.51±3.13)vs(12.60±3.52)m L·kg-1·min-1],HR peak也明显增加[(116.26±10.98)vs(104.53±11.79)min-1],且差异均有统计学意义(P0.05)。使用四肢联动的患者疲劳程度较自行车轻(Borg呼吸困难:9.95±0.85 vs 14.79±1.23;Borg腿部疲劳:13.53±0.70 vs 15.95±0.85)。纳入研究的19位患者均能顺利完成两次试验,没有发生任何不良事件。结论:四肢联动在评估卒中患者心肺适能方面是安全、有效、可行的,其测试结果更贴近患者真实的心肺功能,并且不容易引起患者疲劳。     

Ventilatory efficiency and rate of perceived exertion in obese and non-obese children performing standardized exercise

Sixty children, in the age span 6-17 years originally divided into two groups, matched by age, sex and height--30 obese subjects [15 girls/15 boys; body mass index (BMI) = 27.4 +/- 4.5 m kg-2; ideal body weight (IBW) range = 122-185%] and 30 controls (BMI = 18.8 +/- 2.7 m kg-2) performed incremental treadmill exercise test. Perceived exertion was assessed by means of Category-Ratio Borg scale. The duration of the exercise for the children in the obesity group was significantly shorter than controls (P = 0.010) but obese children have greater absolute values for oxygen uptake (VO2peak ml min-1 = 1907 +/- 671 versus 1495 +/- 562; P = 0.013) and ventilatory variables (VE, VT), which adjusted for body mass decrease significantly (VO2/kg ml min-1 kg-1 = 29.2 +/- 3.8 versus 33.6 +/- 3.5; P < 0.001). Among the various methods for 'normalizing' absolute values of VO2peak for body size, dividing it by body surface area (BSA) yielded the best results (VO2/BSA ml min-1 m-2 = 43.5 +/- 4.6 versus 44.7 +/- 5.6; P = 0.335). The ventilatory efficiency determined either as a slope of VE versus VCO2 or as a simple ratio at anaerobic threshold did not differ between obese and non-obese children in the incremental and recovery periods of exercise. There was a negative correlation of VE/VCO2 slope with age and anthropometric parameters. Obese children rated perceived exertion significantly higher than controls despite the standard workload (Borg score = 6.2 +/- 1.2 versus 5.2 +/- 1.1; P = 0.001). In conclusion, the absolute metabolic cost of exercise is higher in the obesity group compared with the control subjects. Both groups have similar ventilatory efficiency but an increased awareness of fatigue that furthermore limits their physical capacity.     

个体化适度运动改善肺动脉高压患者心肺功能的效果

目的 分析病情稳定的肺动脉高压(PAH)患者心肺功能状况,探讨运用心肺运动试验(CEPT)精准制定个体化适度运动处方对PAH患者心肺功能储备及运动耐量的影响。方法 2018年4月至2019年7月,纳入病情稳定的PAH患者(PAH组,n= 31)和体检正常的健康人(正常组n = 32),入组前均进行CPET。PAH组行6分钟步行试验(6MWT)后,随机分为运动康复组(n = 16)和对照组(n = 15),运动康复组在规范靶向药物治疗的基础上进行个体化适度运动训练,每周5 d,共8周。对照组仅进行常规靶向药物治疗。治疗后两组再次行CPET和6MWT。结果 治疗前,与正常组相比,PAH组体质量、体质量指数(BMI)、用力肺活量(FVC)、第一秒用力呼气容积(FEV₁)、最大通气量(MVV)、无氧阈(AT)、峰值心率(HRpeak)、峰值收缩压(SBPpeak)、峰值负荷功率(WRpeak)、峰值摄氧量(VO₂peak)、峰值氧脉搏(VO₂/HRpeak)、峰值心排量(COpeak)、峰值分钟通气量(VEpeak)、峰值潮气末二氧化碳分压(P_ETCO₂peak)、峰值脉氧饱和度(SpO₂peak)、摄氧通气效率峰值平台(OUEP)均降低(t > 2.419, P < 0.05);静息心率(HRrest)、峰值生理无效腔与潮气量比值(V _D/V_Tpeak)、二氧化碳排出通气效率最低值(Lowest VE/VCO₂)、二氧化碳排出通气斜率(VE/VCO₂slope)均升高(|t| > 2.615, P< 0.05)。治疗后,对照组FEV₁、MVV、峰值千克摄氧量[VO₂peak (ml/min/kg)]、VO₂/HRpeak降低(t > 2.272, P < 0.05);运动康复组FVC、FEV ₁、MVV、AT、SBPpeak、WRpeak、VO₂peak、VO₂/HRpeak、COpeak、VEpeak、P_ETCO₂peak、SpO₂peak和6分钟步行距离(6MWD)升高(|t| >2.167,P < 0.05),Lowest VE/VCO ₂、VE/VCO₂slope降低(t > 2.264, P < 0.05)。与对照组相比,运动康复组FEV ₁/FVC、AT、WRpeak、VO₂peak、VO₂/HRpeak、COpeak、6MWD升高(|t| >2.168, P < 0.05)。 结论 病情稳定的PAH患者整体心肺功能较正常人仍有降低。CPET精准指导的个体化适度运动处方可以有效改善PAH患者的心肺功能储备,提高PAH患者的运动耐量。     

Oxygen consumption and cardiac response of short-leg and long-leg prosthetic ambulation in a patient with bilateral above-knee amputation: comparisons with able-bodied men

This study measured oxygen uptake (VO2), minute ventilation (VE), and heart rate (HR) in a bilateral above-knee (AK) amputee and in three able-bodied controls during progressive treadmill exercise. Walking conditions for the amputee included using bilateral short-leg (SL) and long-leg (LL) prostheses. A progressive treadmill protocol to maximal capacity was used for the amputee and duplicated by the control subjects. An automated system was used to measure VO2, VE, and HR throughout exercise. Data analysis was restricted to the use of parameter averages and percentages to describe differences between experimental conditions. Maximal VO2 for the amputee averaged 23.3mL/kg-1/min-1 with the LL and 22.8mL/kg-1/min-1 with the SL prostheses, a negligible difference between conditions; however, exercise duration was 27% longer when using the SL prostheses. In addition, when averaged over the first four stages of exercise, VO2, VE, and HR were 24%, 32%, and 14% higher, respectively, when the LL prostheses were used. Treadmill walking by unimpaired controls averaged 47% and 79% more economical than walking with the SL or LL prostheses, respectively. These results demonstrate that the use of currently available AK prostheses requires significant energy expenditure, which limits their use to only the most physically fit individuals.     

The effects of posture on the metabolic and ventilatory response to low level steady state exercise

Low level exercise is frequently used to assess cardiac and pulmonary function. This study examines the differences in both metabolic and respiratory patterns between the sitting and supine position. Six normal male subjects were studied in both positions during four levels of exercise (12.5, 25, 37.5 and 50 W). Oxygen consumption (VO2), carbon dioxide production (VCO2) and minute ventilation (VE) were greater when sitting as were the ventilatory equivalents to O2 (VE/VO2) and CO2 (VE/VCO2). Respiration was compared at equivalent workloads; the greater minute ventilation observed during sitting was due to greater tidal volumes (VT) and mean inspiratory flows (VT/TI). Expiratory time (TE) was longer and inspiratory duration shorter under most conditions when sitting. When breathing patterns were compared at similar degrees of minute ventilation, VT, TE and VT/TI were greater when sitting, while respiratory frequency (fR) was slower.     

Effects of ventilator resetting on indirect calorimetry measurement in the critically ill surgical patient

OBJECTIVE: To evaluate the effect of acute changes in minute ventilation (VE) on oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory quotient, and energy expenditure during volume-controlled mechanical ventilation in the critically ill surgical patient. The effects on some oxygen transport variables were assessed as well. DESIGN: Prospective, randomized clinical study SETTING: Adult surgical intensive care unit of a university teaching hospital. PATIENTS: Twenty adult critically ill surgical patients were studied during volume-controlled mechanical ventilation. INTERVENTIONS: After a basal period of stability (no changes over time in body temperature, energy expenditure, blood gases, acid-base status, cardiac output, and ventilatory parameters), VE was then randomly either increased or reduced (+/-35%) by a change in tidal volume (VT), while respiratory rate and inspiratory/expiratory ratio were kept constant. Settings were then maintained for 120 mins. During the study, patients were sedated and paralyzed. MEASUREMENTS AND MAIN RESULTS: VO2, VCO2, and respiratory quotient were measured continuously by a Nellcor Puritan Bennett 7250 metabolic monitor (Nellcor Puritan Bennett, Carlsbad, CA). Hemodynamic and oxygen transport parameters were obtained every 15 mins during the study. Despite large changes in VE, VO2 and energy expenditure did not change significantly either in the increased or in the reduced VE groups. After 15 mins, VCO2 and respiratory quotient changed significantly after ventilator resetting. VCO2 increased by 10.5 +/- 1.1% (from 2.5 +/- 0.10 to 2.8 +/- 0.12 mL/min/kg, p< .01) in the increased VE group and decreased by 12.4 +/- 2.1% (from 2.7 +/- 0.17 to 2.4 +/- 0.16 mL/min/kg, p< .01) in the reduced VE group. Similarly, respiratory quotient increased by 16.2% +/- 2.2% (from 0.87 +/- 0.02 to 1.02 +/- 0.02, p< .01) and decreased by 17.2% +/- 1.8% (from 0.88 +/- 0.02 to 0.73 +/- 0.02, p< .01). VCO2 normalized in the reduced VE group, but remained higher than baseline in the increased VE group. Respiratory quotient did not normalize in both groups and remained significantly different from baseline at the end of the study. Cardiac index, oxygen delivery, and mixed venous oxygen saturation increased, while oxygen extraction index decreased significantly in the reduced VE group. Neither of the mentioned parameters changed significantly in the increased VE group. CONCLUSIONS: We conclude that, during controlled mechanical ventilation, the time course and the magnitude of the effect on gas exchange and energy expenditure measurements caused by acute changes in VE suggest that VO2 and energy expenditure measurements can be used reliably to evaluate and quantify metabolic events and that VCO2 and respiratory quotient measurements are useless for metabolic purposes at least for 120 mins after ventilator resetting.     

The "Low Intensity Treadmill Exercise" Protocol for Appropriate Rate Adaptive Programming of Minute Ventilation Controlled Pacemakers

The objective of rate adaptive pacemakers that measure minute ventilation by tmnsthoracic impedance is to simulate the physiological relationship of the sensed signal to the sinus node response during exercise, thus achieving an appropriate matching of heart rate with patient effort. The purpose of this study was to determine the physiological relationship between heart rate and minute ventilation (HR/VE) during peak exercise testing in order to develop a database for appropriate rate adaptive slope programming of minute ventilation controlled pacemakers. Due to several clinical limitations of peak exercise testing, it was additionally determined whether the 35-watt “low intensity treadmill exercise” (LITE) protocol can be used as a substitute for peak exercise test using the “ramping incremental treadmill exercise” (RITE) protocol in order to assess the correct HR/VE slope below the anaerobic threshold. The stress tests were performed on a treadmill with the collection of breath-by-breath gas exchange. Linear regression analysis was used to determine the HR/VE slope below and above the anaerobic threshold and during the early, dynamic phase of low intensity exercise with the RITE and LITE protocols, respectively. The results of this testing in 41 healthy subjects demonstrated that the HR/VE relationship throughout treadmill exercise using the RITE protocol was not linear but curvilinear in nature, with a steeper HR/VE slope of 1.54 ± 0.51 below versus 1.15 ± 0.37 above the anaerobic threshold (P < 0.005). The HR/VE slope determined during the early, dynamic phase of the LITE protocol (1.58 ± 0.88) did not differ from the HR/VE slope from rest to anaerobic threshold obtained using the peak exercise RITE test (1.54 ± 0.51; P = 0.79), Rate adaptive pacing should simulate the curvilinear relationship between heart rate and minute ventilation from rest to peak exercise. The HR/VE slope determined during the early, dynamic phase of low intensity exercise represents the HR/VE slope derived from the RITE protocol below the anaerobic threshold. According to the peak exercise database, the slope above anaerobic threshold can easily be calculated as a percentage of the slope below the anaerobic threshold. The LITE protocol can, therefore, be effectively performed as a substitute for peak exercise stress tests to determine the correct pacemaker rate response factor in order to obtain a physiological heart rate to minute ventilation relationship for the appropriate matching of paced heart rate with patient effort.     

Recent advance of exercise test in clinical cardiology concerning heart failure

Present review focused on the recent advance and clinical application of exercise test in cardiology. Exercise intolerance is considered as one of clinical essential feature in patients with heart failure. Cardiac dysfunction induces systemic disorders including motor muscle and vasculature, and then limits exercise performance through direct and indirect pathway. Parameters of exercise test consist of subjective indexes such as NYHA functional class, and objective evaluations such as cardiopulmonary exercise test(CPX). Especially, we discussed the parameters of CPX provided many indexes, for example peak VO2, VE/VCO2 slope and deltaVO2/Work rate. These various indexes have different clinical meanings among each other. Low value of peak VO2, which reflected both disturbances of central and peripheral factors, is reported to result in poor survival rate. Although VE/VCO2 slope similarly predicts the prognosis, it thought to be mediated through a different way. We concluded that exercise test is important to understand the pathophysiological feature of heart failure as a systemic disease.     

Metabolic and ventilatory responses during very low level exercise

1. Nine male and six female healthy subjects were studied during supine bicycle exercise at workloads of 12 and 37 W; pedalling rates varied between 30 and 50 cycles/min at each workload. Measurements were made of oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE), tidal volume (VT), respiratory frequency (fR), inspiratory and expiratory time (TI, TE) and mean inspiratory flow (VT/TI) using a non-invasive canopy-computer-spirometer system. 2. At rest, males had greater values of VE, VT, TI, inspiratory duty cycle (TI/TTOT), VCO2 and VO2, and a lower fR, than females. 3. At the lower workload, VO2, VCO2, VE, VT and VT/TI increased linearly with increasing pedalling rate, whereas at the higher workload there was a decrease in VO2 and little or no change in ventilatory parameters from 30 to 50 cycles/min except for an increase in fR in females. 4. While performing supine exercise, there was an effect of pedalling rate on ventilatory and metabolic parameters at the low workload (12 W) which diminished at the higher workload (37 W). An increase in pedalling rate appears to enhance efficiency at these low workloads. 5. Differences between the sexes during exercise generally include: (a) a higher breathing frequency, (b) a greater mechanical efficiency, and (c) lower ventilatory equivalents of O2 and CO2 (VE/VO2 and VE/VCO2) during the higher workload in females than males.