合并慢性阻塞性肺疾病对腹腔镜胆囊摘除手术的影响105例分析

目的：探讨合并慢性阻塞性肺疾病（COPD）对腹腔镜胆囊摘除手术的影响因素及围手术期处理。方法：对105例合并COPD患者术前检查肺功能、血气分析，个体化采取消炎、改善通气治疗后行腹腔镜胆囊摘除手术（LC）。结果：3例因肺功能状况差改为内科治疗，102例成功实施手术，6例术后合并呼吸道感染，1例术后合并呼吸衰竭，无手术中、手术后死亡。3例内科治疗病例均MVV〈40％预计值，FVC〈35％预计值，FEV1〈35％预计值。其中1例合并低氧血症（PaO2〈60mmHg）。结论：对合并COPD适于LC的患者，肺功能检查MVV〉40％预计值，FVC、FEV1〉35％预计值，采取必要的术前准备、熟练的手术操作、术后呼吸管理及治疗，是能够耐受LC手术的。     

11例最大自主通气量小于50%胸肺手术临床分析

1993～1995年，我院外科为最大自主通气量（MVV）＜50％的11例病人成功地进行了胸肺部手术。我们认为肺功能低于手术指标的病人，能否胜任胸肺部手术，应从病情、病种、手术方式、手术范围及术后监护等方面综合分析确定。回．临床资料11例中男10例，女1例；年龄17～75岁。其中，肺癌5例，肺大泡、肺结核、纵隔畸胎瘤、肺转移癌、脓气胸、右全肺切除术后支气管胸膜疾各1例；7例行肺叶切除，4例分别进行了纵隔肿瘤摘除、胸膜剥脱、胸廓改形术。术前肺功能及动脉血氧分压（PaO2）平均值：MVV41．35士10．76％（14．3％～49．9％）、FEV11…     

阻塞性通气功能障碍患者肺切除术后肺功能评价

本文探讨阻塞性通气功能障碍患者肺叶切除术后肺功能及动脉血气的改变。由于术后肺组织代偿功能成退,肺功能随肺切除范围顺序递减的幅度比肺功能正常者的幅度增大,特别是MVV更显著,PaO_2术后明显下降,与术前比较有明显差异(P<0.05)。最大通气量测定配合动脉血气分析可对大部分手术病例的手术指征和安全性作出较于靠的评价。     

慢性阻塞性肺疾病患者呼吸肌强度与肺功能的关系

目的:探讨慢性阻塞性肺疾病(COPD)患者的呼吸肌强度及其与肺功能的关系。方法:测定30例COPD患者犤男5例,女15例,平均年龄(72+3)岁犦的呼吸肌力犤最大吸气压(MIP)、最大±呼气压(MEP)犦和肺功能犤用力肺活量(FVC)、第1秒用力呼气量(FEV1)、第1秒用力呼气量占第1秒用力呼气量百分比(FEV1/FVC),最大通气量(MVV)犦,计算各个对象实测值占其预计值百分比,并计算呼吸肌力与肺功能的相关性。结果:COPD患者呼吸肌强度和肺功能均明显低于其预计值(慢阻肺患者的MIP仅占其预计值的(56±11)%,MEP仅占预计值的(46±11)%,肺功能仅达到预计值的48%～71%;COPD患者的呼吸肌力与其肺功能指标呈显著相关。结论:COPD患者肺功能减退与其呼吸肌强度衰弱密切关联,改善呼吸肌状态有利于提高COPD患者的呼吸功能。     

核素肺灌注显像定量预测肺癌术后肺功能

目的 :探讨核素肺灌注显像定量预测肺癌术后肺功能的临床意义。方法 :将 2 1例肺癌患者按手术方式分为全肺切除组和肺叶切除组 ,肺灌注显像结合常规肺功能检查 ,比较第 1秒用力呼气量 (FEV1)术前预测值与术后实测值的相关关系。结果 :使用该方法定量预测术后肺功能 ,FEV1术前预测值与术后实测值呈显著正相关。2 1例患者均痊愈出院 ,随访无一例有肺功能不全。结论 :核素肺灌注显像定量预测肺癌术后肺功能 ,可作为评估肺癌手术安全性的可靠指标。     

慢性阻塞性肺疾病患者呼吸肌强度与肺功能的关系

目的：探讨慢性阻塞性肺疾病(COPD)患者的呼吸肌强度及其与肺功能的关系。方法：测定30例COPD患者[男5例，女15例，平均年龄(72+3)岁]的呼吸肌力[最大吸气压(MW)、最大&;#177;呼气压(MEP)]和肺功能[用力肺活量(FVC)、第1秒用力呼气量(FEVl)、第1秒用力呼气量占第1秒用力呼气量百分比(FEV1／FVC)，最大通气量(MVV)]，计算各个对象实测值占其预计值百分比，并计算呼吸肌力与肺功能的相关性。结果：COPD患者呼吸肌强度和肺功能均明显低于其预计值(慢阻肺患者的MIP仅占其预计值的(56&;#177;11)％，MEP仅占预计值的(46&;#177;11)％，肺功能仅达到预计值的48％-7l％；COPD患者的呼吸肌力与其肺功能指标呈显著相关。结论：COPD患者肺功能减退与其呼吸肌强度衰弱密切关联，改善呼吸肌状态有利于提高COPD患者的呼吸功能。     

单操作孔胸腔镜肺段切除治疗高龄肺结节患者临床疗效分析

目的:探讨单操作孔胸腔镜肺段切除在高龄肺结节患者中的应用经验。方法:2016年5月至2017年12月共对32例70岁以上肺结节患者行单操作孔胸腔镜下肺段切除,其中男性23例,女性9例;年龄71～85(75.6±6.5)岁;所有患者健侧卧位,于腋中线第7或第8肋间做腔镜孔,腋前线第3～4肋间做2～3 cm操作孔,行解剖性肺段切除。结果:所有患者均顺利完成手术,包括右上肺尖段切除5例,右上肺后段切除6例,右上肺前段切除4例,右下肺背段切除5例,左上肺尖后段切除5例,左上肺舌段切除3例,左下肺背段切除4例,肺结节直径7～22(13.6±6.3) mm,手术时间42～166(86.6±36.3) min,术中出血50～200(85.5±54.8) mL,术后住院时间4～8(5.6±3.3) d。住院期间无死亡病例,1例术后肺不张,1例肺持续性漏气大于3 d,经治疗后痊愈,其余均顺利恢复。结论:单操作孔全胸腔镜下肺段切除创伤小,并发症少,有利于高龄肺结节患者术后恢复。     

患有慢性阻塞性肺疾病的老年军人330例生活质量现状调查

目的:调查慢性阻塞性肺疾病老年军人的生活质量、病情严重程度、肺功能分级及治疗情况。方法:①于2004-04/09对以往确诊为慢性阻塞性肺疾病的定居成都市24个干休所师以上离休干部330例进行调查,均为男性,年龄70～87岁。均符合中华医学会呼吸病学分会慢性阻塞性肺疾病诊治规范,且对调查和检查项目知情同意。②采用自拟生活质量问卷调查(呼吸症状、活动受限、疾病影响、经济状况)纳入对象生活质量,该问卷共计0～100分,分值越低代表慢性阻塞性肺疾病患者的健康状况越好,≥40分为生活质量较差,≥70分为生活质量极差。进行血气分析(动脉血氧分压、二氧化碳分压、血氧饱和度)。③采用德国耶格公司的高级组合式肺功能仪(Masterscreen系列)进行通气功能检查,包括第1秒用力呼气量占预计值的百分比、每分钟最大通气量实测值占预计值的百分比。④慢性阻塞性肺疾病分级:Ⅰ级(轻度):第1秒用力呼气量占预计值的百分比≥70%;Ⅱ级(中度):第1秒用力呼气量占预计值的百分比为50%～69%;Ⅲ级(重度):第1秒用力呼气量占预计值的百分比<50%。⑤肺功能分级:基本正常:每分钟最大通气量实测值占预计值的百分比>81%,第1秒用力呼气量占预计值的百分比>71%,血氧饱和度>94%,氧分压>11.57kPa,二氧化碳分压<5.99kPa;轻度减退:前述5项指标分别为71%～80%,61%～70%,>94%,>11.57kPa,<5.99kPa;显著减退:分别为51%～70%,41%～60%,90%～93%,9.98～11.57kPa,<5.99kPa;严重减退:分别为21%～50%,≤40%,82%～89%,7.98～9.97kPa,>7.99kPa;呼吸衰竭(除外第1秒用力呼气量占预计值的百分比):分别为<20%,<82%,<7.98kPa,>7.99kPa。结果:①吸烟史及合并症:纳入对象吸烟史30～60年,93.6%每年吸烟量≥400支。88.8%合并其他疾病。②生活质量比较差78例(23.6%),生活质量极差9例(2.7%)。③慢性阻塞性肺疾病分级:Ⅰ级65例(19.7%),Ⅱ级166例(50.3%),Ⅲ级99例(30%)。④肺功能:基本正常0例,轻度减退151例(45.8%),显著减退138例(41.8%),严重减退39例(11.8%),呼吸衰竭2例(0.6%)。⑤治疗情况:需长期用药及家庭氧疗的39例(11.8%),需长期住院的9例(2.7%)。每年住院天数≥100d48例(14.6%),<100d,≥30d51例(15.5%)。⑥发病年龄:50～59岁发病118例(35.8%),60～69岁发病184例(55.8%),70～79岁发病28例(8.5%)。结论:慢性阻塞性肺疾病老年军人有长期大量吸烟史,且合并其他疾病;发病年龄集中在50～69岁;生活质量差、肺功能严重减退、需长期住院治疗的占小部分。     

肺切除术后急性呼吸衰竭高危因素分析和护理对策

目的：为有效地预防肺切除术后发生急性呼吸衰竭（呼衰）。方法：找出围术期可能导致呼衰的高危因素，因人施护。结果：术前肺活量占预计值的（VC％）＜70％，第一秒用力呼气容积占用力肺活量的百分率（FEV1％）＜70％，最大通气量占预计值的百分率（MVV％）＜50％，列气容积／肺总量的比值（RV／TLC）＞50％术后急性呼衰的发生率较高。手术当日大量输液与术后急性呼衰的发生有正相关。部分肺切除的呼衰发生可能性低于全肺切除。结论：年龄＞65岁，过度肥胖，长期吸烟，术前慢性呼吸系统疾病及心肺功能，全肺切除术后出现胸内并发症，围术期输液量过多过快是肺切除术后发生急性呼衰的高危因素。对高危人群加强病情观察，实施个体化护理，可有效预防呼衰的发生。     

胸腔镜肺段切除术和肺叶切除术治疗老年早期非小细胞肺癌患者的疗效比较

目的探讨胸腔镜肺段切除术和胸腔镜肺叶切除术治疗老年早期非小细胞肺癌(NSCLC)患者的疗效差异。方法回顾性分析接受胸腔镜切除手术(VATS)的82例老年早期NSCLC患者的临床资料,将34例接受胸腔镜肺段切除术的患者纳入肺段切除组,将48例接受胸腔镜肺叶切除术的患者纳入肺叶切除组。比较2组患者围术期相关指标,并比较术后12个月随访结果及肺功能检测情况。结果 2组手术出血量、淋巴结清扫数、术后引流量、住院时间和住院费用比较,差异均无统计学意义(P 0. 05);肺段切除组手术耗时(170. 43±25. 90) min,显著长于肺叶切除组的(158. 70±22. 76) min (P 0. 05);肺段切除组近期手术并发症发生率为8. 82%,低于肺叶切除组的12. 50%,但差异无统计学意义(P 0. 05);术后12个月随访显示,2组均未出现肿瘤复发、转移或死亡病例,而肺段切除组患者肺功能指标用力肺活量(FVC)、第1秒用力呼气容积(FEV1)和最大通气量(MVV)的下降率均显著低于肺叶切除组(P 0. 05)。结论胸腔镜肺段切除术和肺叶切除术均是治疗老年早期NSCLC患者的有效微创术式,二者近期手术疗效相近,但前者对患者肺功能的影响较小,尤其适用于肺功能较差或不耐受肺叶切除的老年NSCLC患者。     

Effects of iohexol on ventilatory functions in patients undergoing diagnostic coronary angiography

Background and objectives Adverse respiratory reactions have been reported with intravascular radiographic contrast media. The aim of the present study is to assess the effects of iohexol on pulmonary functions in patients undergoing diagnostic coronary angiography (CA). Materials and methods: 30 patients enrolled in the study. The respiratory functions of the patients were measured at three different stages during angiography (before, immediately after and 2 h later) and arterial blood gas analyses were performed at six stages during CA (before, immediately after the insertion of angiography catheter, 2 min after the injection of contrast agent, at the end of angiography, an hour and 2 h after angiography). A single, experienced angiographer performed the angiography procedures via radial artery route. Totally six multiple angled views of the left and right coronary arteries were recorded in all patients by hand injection. None of the patients were performed ventriculography. Results: Angiography caused significant reduction in forced expiratory volume in 1 sec [FEV₁] (from 103 ± 15 to 95 ± 17, p < 0.01), forced vital capacity [FVC] (from 99 ± 13 to 95 ± 18, p < 0.05) and maximum mid-expiratory flow rate [MMF] (from 95 ± 33 to 84 ± 29, p < 0.01) whereas there were no significant changes in the mean FEV₁/FVC ratios at different stages of angiography. Statistically significant decrease in PaO₂ (from 91 ± 10 to 85 ± 13 mmHg, p < 0.01) and arterial O₂ saturation (from 97 ± 1% to 96 ± 1%, p < 0.01) were also observed. Data in present study showed a clinically insignificant but statistically significant restrictive impairment in pulmonary functions. Conclusions: Diagnostic CA using iohexol decreases ventilatory functions in a small but significant extent in patients without any overt pulmonary disease.     

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.     

A target feedback device for ventilatory muscle training

In a previous study, we successfully used a target feedback device, together with an external resistor, to train the ventilatory muscles of patients with chronic obstructive pulmonary disease. In this article, we describe the details of the design and function of the target feedback device. When used in conjunction with an external resistance, the target feedback device provides timing and pressure targets, together with feedback information, on whether these targets are achieved. The target feedback device consists of readily available electronic components and is relatively simple to construct. Adjustment of an external pressure knob permits setting of pressure targets. Adjustment of internal components is possible and allows control of breathing frequency, inspiratory time, and breathing waveform.     

Human G protein β3 subunit variant does not alter hypercarbic or hypoxic ventilatory response

Hypercarbic respiratory drive is mainly determined by P_CO2 and pH with activity of the intracellular Na⁺/H⁺ exchanger (NHE) playing an important role in maintaining intracellular pH and respiratory drive. Because NHE activity varies with genetically different G‐protein β3 subunits (GNB3) (C/T polymorphism at nucleotide position 825) different genotypes might alter respiratory regulation. To test the hypothesis that short‐term ventilatory responses vary with different GNB3 healthy volunteers with different genotypes (CC, TC, TT) were exposed to either hyperoxic hypercarbia (n=33) or to isocapnic hypoxia (n=31), respectively. There was no difference between CC, TC, and TT genotypes in hypercarbic and hypoxic respiratory drive when assessed as the ratio of minute ventilation over endexpiratory P_CO2 changes (ΔV˙E /ΔPET _CO2), maximal tolerable PET _CO2, and ratio of changes in ventilation over arterial haemoglobin desaturation (ΔV˙_E/ΔS_O2), respectively. Thus, short‐term hypercarbic and hypoxic ventilatory drive do not differ between individuals with genotypes encoding different GNB3. Whilst respiratory control may still be influenced by G‐protein aberration, other mechanisms seem to have a more important role in controlling ventilation.     

Study on the effect of oral administration of carbocisteine on ventilatory parameters in the SO2 inhalation model of bronchitis in the rat

In order to study the physiological correlates of the beneficial action of carbocisteine (S-carboxy-methyl-cysteine), we have measured the changes occurring in ventilatory parameters in rats made bronchitic by prolonged exposure (2 weeks) to air containing sulfur dioxide (SO2). In animals treated with distilled water (1 ml/100 g/day), statistically significant (P < 0.05) changes in respiratory frequency (-20%) and tidal volume (+31%) were found. As a result of these opposing changes, the ventilation/min was stable. Moreover, the compliance was decreased (33%, P < 0.05) and the resistance was greatly enhanced (+ 99%, P < 0.05). The concomitant administration of carbocisteine (500 mg/kg po/day) with SO2 inhalation significantly (P < 0.05) prevented the development of resistance without effecting significant changes in the other parameters except for a slight improvement in ventilation/min. In conclusion, this improved respiratory resistance in the bronchitic carbocisteine-treated animals tallies with a decrease in mucus retention associated with the return to normal of rheological characteristics of the secreted mucus.     

Determination and possible application of the aerobic gas exchange threshold in aerobically untrained paraplegic subjects based on stimulated cycle ergometry

Purpose. To accurately characterise cardiopulmonary baseline performance in aerobically untrained paraplegic subjects by means of an incremental exercise test (IET) and to derive possible training recommendations based on these measurements.

Methods. Twelve motor complete paraplegic subjects with no previous experience in stimulated leg-cycling participated in the study. Exercise testing was performed on a recumbent FES-tricycle by means of a work rate and cadence controlled IET until maximal work rate was reached. Heart rate (HR) and respiratory parameters were recorded continuously.

Results. Peak oxygen uptake was 671 ± 192 mL min^?1 (mean ± standard deviation), peak HR 90 ± 12 beats min^?1, net peak power 8.4 ± 3.3 W and peak minute ventilation 23.6 ± 7.5 L min^?1. Aerobic gas exchange threshold (GET) was found to be 51% ± 10% of peak oxygen uptake and corresponded to 41% ± 13% of peak power.

Conclusions. A cadence and work rate controlled exercise test allows the determination of cardiopulmonary parameters during stimulated cycle ergometry even in aerobically untrained paraplegic subjects. The precise determination of GET allows an appropriate exercise intensity to be prescribed and thus provides a suitable method for exercise intensity calculation in the spinal cord injured population in the future.     

A clinical pharmacological study of the potential beneficial effects of a propolis food product as an adjuvant in asthmatic patients

The aqueous extract of propolis has been formulated as a nutritional food product and administered, as an adjuvant to therapy, to patients with mild to moderate asthma daily for 2 months in the framework of a comparative clinical study in parallel with a placebo preparation. The diagnosis of asthma was made according to the criteria of patient classification of the National Institutes of Health and Global Initiative for Asthma Management. At inclusion, the pulmonary forced expiratory volume in the first second (FEV1) as a percentage of the forced vital capacity (FVC) was more than 80% in mild persistent cases, and between 60 and 80% in moderate persistent cases, showing an increase in the degree of reversibility of > 15% in FEV1. All patients were on oral theophylline as controller therapy, none was receiving oral or inhaled corticosteroids, none had other comorbidities necessitating medical treatment, and all were from a middle-class community and had suffered from asthma for the last 2-5 years. Twenty-four patients received the placebo, with one drop-out during the study, while 22 received the propolis extract, with no drop-outs. The age range of the patients was 19-52 years; 36 were male and 10 female. The number of nocturnal attacks was recorded on a weekly basis, while pulmonary function tests were performed on all patients at the beginning of the trial, 1 month later and at the termination of the trial. Immunological parameters, including various cytokines and eicosanoids known to play a role in asthma, were measured in all patients at the beginning of the trial and 2 months later. Analysis of the results at the end of the clinical study revealed that patients receiving propolis showed a marked reduction in the incidence and severity of nocturnal attacks and improvement of ventilatory functions. The number of nocturnal attacks dropped from an average of 2.5 attacks per week to only 1. The improvement in pulmonary functions was manifested as a nearly 19% increase in FVC, a 29.5% increase in FEV1, a 30% increase in peak expiratory flow rate (PEFR), and a 41% increase in the forced expiratory flow rate between 25 and 75% of the vital capacity (FEF25-75). The clinical improvement was associated with decreases by 52, 65, 44 and 30%, respectively, of initial values for the pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, ICAM-1, interleukin (IL)-6 and IL-8, and a 3-fold increase in the 'protective' cytokine IL-10. The levels of prostaglandins E2 and F2alpha and leukotriene D4 were decreased significantly to 36, 39, and 28%, respectively, of initial values. Patients on the placebo preparation showed no significant improvement in ventilatory functions or in the levels of mediators. The findings suggest that the aqueous propolis extract tested is potentially effective as an adjuvant to therapy in asthmatic patients. The benefits may be related to the presence in the extract of caffeic acid derivatives and other active constituents.     

阻塞性通气障碍在呼吸波形上特异性改变临床观察研究

目的：阻塞性通气障碍在呼吸波形上特异性改变临床观察研究。方法：在不影响临床诊治前题下，对入选病例呼吸波形进行动态监测，研究阻塞性通气障碍病人呼吸波形改变与相应病情和医疗等情况的相关性及其在呼吸波形上特征性改变的临床意义。结果：阻塞性通气障碍呼吸波形与正常波形相比，在压力、容量、流速曲线和压力一容量环上有连续、剧烈顿挫的特征性改变。其改变的幅度、大小、频率与阻塞性通气障碍引起病理变化程度相关。模拟液体阻塞气道实验也可得到类似特异性改变波形。结论：阻塞性通气障碍患者在正压通气时，呼吸波形根据通气障碍类型分别可出现“锯齿”状、“波纹”状、“鸭头”状、“鸟头”状、“火炬”状等具有典型特征的特异性呼吸波形。这对其临床快速诊治有重要指导意义。     

急腹症病人采用腹腔镜手术对通气功能影响的初步探讨

目的探讨腹腔镜外科手术对肺通气功能的影响。方法通过对45例腹部外伤、急腹症病人行腹腔镜手术治疗前后肺通气功能(VC,MVV,FVC,FEV⒈/FVC%)的检测,评价腹腔镜手术治疗对肺通气功能的影响。结果45例病人手术治疗前后肺通气功能无明显变化。结论腹腔镜外科手术对肺通气功能无明显影响。     

Effects of induced hypotension on breathing pattern in halothane-anaesthetized man

Abstract. The effects of hypotension induced by trimetaphan on ventilatory control were assessed in sixteen normal subjects under halothane anaesthesia. The breathing pattern, mouth occlusion pressures, lung mechanics, acid-base balance, and arterial blood gases were analysed before and during trimetaphan infusion. During induced hypotension, the only significant change in the ventilatory variables was an increase in the ratio of inspiratory duration to total cycle duration from 0.39 ± 0.05 (SD) to 0.42 ± 0.03; P < 0.01. The average minute ventilation remained unchanged. No modification in lung mechanics was observed, but all subjects developed a slight but significant hypocapnic alkalosis: PaCO₂ was reduced from 5.5 ± 0.4 to 5.2 ± 0.4 kPa ( P ± 0.001) and pH increased from 7.34 to 7.36 ( P < 0.05), without change in standard bicarbonate concentration.
Our data indicate that the reduction in sympathetic nervous system activity induced by trimetaphan infusion in spontaneously breathing man causes only a minor alveolar hyperventilation. The weak respiratory response to hypotension suggests that changing peripheral afferent activity has little influence on the typically rapid breathing pattern induced by halothane.