Airway physiology,autogenic drainage,and active cycle of breathing

Airway clearance techniques are used to aid in mucus clearance in a variety of disease states. Autogenic drainage and active-cycle-of-breathing technique are 2 such modalities that rely heavily on basic airway physiology to enhance clearance. In this review I discuss the equal pressure point, huffing, and asynchronous and collateral ventilation, and review the literature and theory regarding autogenic drainage and active cycle of breathing. Selection of airway clearance techniques is discussed in the light of evidence-based medicine.     

Assisted autogenic drainage in infants and young children hospitalized with uncomplicated pneumonia,a pilot study

Background and purpose

Pneumonia is the most important respiratory problem in low‐to‐middle income countries. Airway clearance therapy continues to be used in children with pneumonia and secretion retention; however, there is lack of evidence to support or reject this treatment. This study aimed to investigate the feasibility of a randomized controlled trial (RCT) on the efficacy and safety of assisted autogenic drainage (AAD) compared to standard nursing care in children hospitalized with uncomplicated pneumonia.

Methods

A single‐blinded pilot RCT was conducted on 29 children (median age 3.5 months, IQR 1.5–9.4) hospitalized with uncomplicated pneumonia. The intervention group received standard nursing care with additional bi‐daily AAD, for 10 to 30 min. The control group only received standard nursing care, unless otherwise deemed necessary by the physician or physiotherapist. The primary outcome measure was duration of hospitalization. The secondary outcome measures included days of fever and supplemental oxygen support; respiratory rate (RR) and heart rate adjusted for age; RR and oxygen saturation pre‐, post‐, and 1‐hr post‐treatment; oxygen saturation; adverse events; and mortality.

Results

No difference was found for duration of hospitalization (median 7.5 and 7.0 days for the control and intervention groups, respectively); however, Kaplan–Meier analysis revealed a strong tendency towards a shorter time to discharge in the intervention group (p = .06). No significant differences were found for the other outcome measures at time of discharge. No adverse events were reported. Within the intervention group, a significant reduction in RR adjusted for age was found.

Discussion

As no adverse events were reported, and AAD did not prolong hospitalization; AAD might be considered as safe and effective in young children with uncomplicated pneumonia. However, a larger multicentred RCT is warranted to determine the efficacy of AAD compared to standard nursing care.     

咳嗽峰流速对拔管结果预测的临床研究

目的 探讨咳嗽峰流速(CPEF)测定对患者拔管脱机结果的预测价值及对预后的影响.方法 选择本院重症监护病房(ICU)2006年11月-2007年12月的200例拔管脱机患者进行前瞻性研究.患者均为经口气管插管接呼吸机辅助呼吸超过24 h者,其意识清楚能合作,且均顺利通过自主呼吸试验30 min.拔管前嘱患者咳嗽,用呼吸机内置肺流量计测定CPEF,取3次最强咳嗽时流速的平均值作为最后测定值.拔管后仔细观察患者的咳嗽情况,按实际咳嗽能力大小将其分为强、中、弱3个等级,如果72 h内患者无需再插管即为拔管脱机成功,同时记录咳嗽能力与拔管结果之间的关系.结果 200例患者中172例拔管成功,28例拔管失败.拔管成功和失败的患者在性别、年龄、疾病严重程度、自主呼吸试验时生命体征等方面比较差异无统计学意义.CPEF是拔管结果的独立预测因子[比值比(OR)<1].区分拔管成功与否的CPEF最佳临界值是58.5 L/min,当CPEF≤58.5 L/min时预测拔管失败的特异性为68.0%,敏感性为71.4%;阳性预测值为0.16,阴性预测值为0.94.拔管脱机的患者咳嗽能力多为"强",极少数为"中";而失败患者咳嗽能力多为"中"或"弱",能力"强"者仅3例.结论 当患者自主呼吸能力逐渐恢复并达到能够完成自主呼吸试验时,气道条件的参数是决定患者拔管结果的重要预测指标.对意识清楚能合作、能通过自主呼吸试验的患者,CPEF是拔管结果强有力的预测因子,是影响拔管成功与否的独立危险因子.CPEF>58.5 L/min的患者拔管成功率高,预后较好;反之,≤58.5 L/ min的患者拔管成功率较低.导致失败的原因多为咯痰不利,咳嗽能力强的患者脱机成功率高,脱机失败的患者预后较差.     

Autogenic drainage: the technique, physiological basis and evidence

Described by Jean Chevaillier in 1967, autogenic drainage is an airway clearance technique that is widely used throughout Europe. The technique is characterised by breathing control, where the individual adjusts the rate, depth and location of respiration in order to clear the chest of secretions independently. This paper describes the technique, based on the work of Chevaillier, offering a physiological explanation for how the technique works. This paper will also review the evidence supporting the use of autogenic drainage.     

呼气负压技术检测呼气流速受限在慢性阻塞性肺疾病中的应用

目的:应用呼气负压技术(NEP)检测慢性阻塞性肺疾病(COPD)患者的呼气流速受限(EFL)。方法:94例COPD患者在坐位及卧位时应用NEP方法检测EFL,即在患者潮气呼吸时于患者口部施加一个-5cmH2O的负压,通过比较施加负压前后的潮气流速-容积曲线来检测EFL。采用EFL五分法与经典的一秒钟用力呼气量(FEV1)方法进行比较。结果:55例COPD患者在坐位及卧位时均存在EFL;23例患者仅于卧位时存在EFL;16例患者坐位及卧位均无EFL。EFL五分法与经典FEV1方法判断肺功能损害程度较一致。EFL五分法与COPD患者的主观呼吸困难分级有更好的相关性。结论:①COPD患者在平静呼吸时EFL普遍存在;②NEP提供了一种简便、快速、无创的方法来检测EFL;③EFL五分法与COPD患者的呼吸困难分级有很好的相关性。     

早期密集拍背、深呼吸咳嗽及体位引流在开胸术后肺不张患者中的作用

目的：探讨早期密集的拍背、深呼吸咳嗽及体位引流在开胸术后肺不张中的作用。方法：选取我院2017年1月1日至2021年9月20日380例开胸手术患者，采用数字表随机法分为2组，试验组193例，对照组187例，在麻醉撤离6小时后行拍背、深呼吸咳嗽及体位引流。 结果：试验组出现肺不张例数为21例，对照组出现肺不张为42例，P＜0.05差异有统计学意义。结论：开胸术后，早期密集的拍背、深呼吸咳嗽及体位引流能够有效避免肺不张，可以临床推广应用     

Endoscopic ultrasonography-guided biliary drainage: rendezvous technique

The success rate of deep biliary cannulation is high but still not perfect in endoscopic retrograde cholangiopancreatography (ERCP), even with aggressive techniques. With the development of linear-array echoendoscopes, the endoscopic ultrasonography-guided rendezvous technique (EUS-RV) has recently emerged as a salvage method for failed biliary cannulation. This review of current literature establishes that EUS-RV is a feasible and safe technique and should be considered as an alternative to percutaneous or surgical approaches. The availability of a percutaneous salvage (if EUS-RV fails) and well-trained endoscopists for both ERCP and EUS are mandatory in minimizing the potential complications of this procedure.     

Positive expiratory pressure and oscillatory positive expiratory pressure therapies

Airway clearance techniques, historically referred to as chest physical therapy, have traditionally consisted of a variety of breathing maneuvers or exercises and manual percussion and postural drainage. The methods and types of airway clearance techniques and devices have rapidly increased in an effort to find a more efficacious strategy that allows for self-therapy, better patient adherence and compliance, and more efficient durations of care. Mechanically applied pressure devices have migrated from European countries over the last several decades to clinical practice in the United States. I conducted a comprehensive MEDLINE search of two such devices: positive expiratory pressure (PEP) and oscillatory positive expiratory pressure (OPEP) and their role in airway clearance strategies. This was followed by a comprehensive search for cross-references in an attempt to identify additional studies. The results of that search are contained and reported in this review. From a methods standpoint, most of the studies of PEP and OPEP for airway clearance are limited by crossover designs and small sample sizes. While PEP and OPEP do not definitively prove superiority to other methods of airway clearance strategies, there is no clear evidence that they are inferior. Ultimately, the correct choice may be an airway clearance strategy that is clinically and cost effective, and is preferred by the patient so that adherence and compliance can be at the very least supported.     

Peak flow and peak cough flow in the evaluation of expiratory muscle weakness and bulbar impairment in patients with neuromuscular disease

OBJECTIVE: To study the expiratory muscle force and the ability to cough estimated by the peak expiratory flow and peak cough flow in patients with Duchenne muscular dystrophy and amyotrophic lateral sclerosis. DESIGN: A total of 27 patients with amyotrophic lateral sclerosis and 52 patients with Duchenne muscular dystrophy were studied. From the group of 144 normal subjects of this laboratory, we selected 38 for comparison. RESULTS: The maximal inspiratory pressure in patients with Duchenne muscular dystrophy and amyotrophic lateral sclerosis was 64.5 +/- 24.7% and 37.8 +/- 21.8%, respectively, and maximal expiratory pressure was 64.2 +/- 32.5% and 37.7 +/- 21.6%, respectively. Patient groups showed a significant lower peak expiratory flow than normal subjects. Higher peak cough flow than peak expiratory flow was found in all groups. The peak cough flow-peak expiratory flow difference was 46 +/- 18% in normal subjects, 43 +/- 23% in patients with Duchenne muscular dystrophy, and 11 +/- 17% in patients with amyotrophic lateral sclerosis. The peak expiratory flow and peak cough flow were not different in bulbar onset amyotrophic lateral sclerosis. In patient groups, the dynamic and static behavior correlated positively. CONCLUSIONS: These results suggest that peak cough flow-peak expiratory flow is useful to monitor expiratory muscle weakness and bulbar involvement and to assess its evolution in these patients.     

Expiratory muscle strength training in persons with multiple sclerosis having mild to moderate disability: effect on maximal expiratory pressure, pulmonary function, and maximal voluntary cough

OBJECTIVE: To determine the effect of expiratory muscle strength training (EMST) on maximal expiratory strength, pulmonary function, and maximal voluntary cough in persons with multiple sclerosis (MS) having mild to moderate disability. DESIGN: Before-after trial. SETTING: Assessments were completed in the privacy of the subject's home or exercise physiology laboratory. PARTICIPANTS: Seventeen persons with MS were age- and sex-matched to 14 healthy controls. INTERVENTION: Eight weeks of EMST and 4 weeks of detraining. MAIN OUTCOME MEASURES: Maximal respiratory pressures, pulmonary function, and maximal voluntary cough were assessed 3 times (pretraining, posttraining, detraining). Maximal expiratory pressure (MEP) was assessed weekly and training intensity adjusted based on the new measurement. RESULTS: Subjects with MS had lower MEP, decreased pulmonary function, and weaker maximal voluntary cough at each assessment. EMST increased MEP and peak expiratory flow. However, improvement in maximal voluntary cough only occurred in subjects with a moderate level of disability when the MS group was subdivided into mild and moderate disability levels based on the Expanded Disability Status Scale. CONCLUSIONS: EMST is a viable tool to enhance the strength of the respiratory muscles. However, further work is needed to determine the best parameters to assess change in cough following EMST.     

Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) variability in asymptomatic never-smoking men

We examined the effects from subjects, technicians and spirometers on within-session variability in successful recordings of forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) in 4989 asymptomatic never-smoking men. All eligible men aged 30–46 years living in western Norway (n = 45 380) were invited to a cross-sectional community survey. Information on respiratory symptoms, smoking habits and occupational exposures was obtained from a self-administered questionnaire. Three successful FEV₁ and FVC recordings were obtained in 26 368 attendants using three dry-wedge bellow spirometers operated by 10 different technicians. Within-subject standard deviation (SD) from three recordings of FEV₁ and FVC was on average 102 and 106 ml, respectively, and increased with height (14 and 17 ml, respectively, per 10 cm) and body mass index (BMI) (11 and 14 ml, respectively, per 5 kg m^?2). Between-subject SD of the mean of three FEV₁ and FVC recordings was 591 and 754 ml, respectively, and increased in groups of increasing height (43 and 40 ml, respectively, per 10 cm). Small, but significant, differences were observed between technicians in within-subject SD and in levels of FEV₁ and FVC. Homogeneity of between-subject variability, necessary for linear regression analysis, was obtained using FEV₁ and FVC divided by height squared. In conclusion, within-subject variability in three successful spirometric recordings was small, but dependent on height and BMI of the subjects as well as technician performance. The observed heterogeneity in between-subject variation in FEV₁ and FVC levels disappeared when each variable was divided by height squared. Novel multiple linear regression equations for FEV₁/height² and FVC/height² were developed to be used in evaluating the effects from occupational airborne exposures in Nordic men aged 30–46 years.     

Neurologic status,cough, secretions and extubation outcomes

Objective To determine the degree to which neurologic function, cough peak flows and quantity of endotracheal secretions affected the extubation outcomes of patients who had passed a trial of spontaneous breathing (SBT).Design Prospective observational study.Setting The medical intensive care unit of a 325-bed teaching hospital.Measurements and main results Cough peak flow (CPF), endotracheal secretions and ability to complete four simple tasks were measured just before extubation in patients who had passed a SBT. Eighty-eight patients were studied; 14 failed their first trials of extubation. The CPF of patients who failed was lower than that of those who had a successful extubation (58.1±4.6 l/min vs 79.7±4.1 l/min, p=0.03) and those with CPF 60 l/min or less were nearly five times as likely to fail extubation compared to those with CPF higher than 60 l/min (risk ratio [RR]=4.8; 95% CI=1.4–16.2). Patients with secretions of more than 2.5 ml/h were three times as likely to fail (RR=3.0; 95% CI=1.0–8.8) as those with fewer secretions. Patients who were unable to complete four simple tasks (i.e. open eyes, follow with eyes, grasp hand, stick out tongue) were more than four times as likely to fail as those who completed the four commands (RR=4.3; 95% CI=1.8–10.4). There was synergistic interaction between these risk factors. The failure rate was 100% for patients with all three risk factors compared to 3% for those with no risk factors (RR=23.2; 95% CI=3.2–167.2). The presence of any two of the above risk factors had a sensitivity of 71 and specificity of 81% in predicting extubation failure. Patients who failed a trial of extubation were 3.8 times as likely to have any two risk factors compared to those who were successful.Conclusions These simple, reproducible methods may provide a clinically useful approach to guiding the extubation of patients who have passed a SBT.     

单侧膝关节表面置换:经皮下引流与关节腔引流及无引流的对照

背景:膝关节表面置换术中是否放置引流以及放置引流的方式,一直都存在争议.目的:在关节腔引流与无引流基础上临床实践了皮下引流,评价皮下引流在单侧膝关节表面置换过程中的价值.方法;通过前瞻性随机对照的方法,将101例拟行单侧膝关节表面置换的患者分为3组,皮下引流组35例,关节腔引流组32例,无引流组34例.分别比较3组患者膝关节表面置换后的引流量、输血量与血红蛋白下降值;并对3组患者的置换后并发症及膝关节功能康复情况进行对比分析.结果与结论:皮下引流组的皮下瘀斑面积(11～30 cm2,>30 cm2)、置换后3 d膝关节周径增加率均小于关节腔引流组及无引流组(P<0.05);皮下引流组输血量、置换后24 h引流量、置换后48 h血红蛋白下降值均低于关节腔引流组(P<0.05).置换后肢体疼痛评分、关节屈曲度、1年随访膝关节感染发生率等方面3组差异无显著性意义(P>0.05).提示单侧膝关节表面置换后放置皮下引流较关节腔引流及无引流有一定优势.     

Affective and metabolic responses to hypnosis, autogenic relaxation, and quiet rest in the supine and seated positions

This study examined the influence of hypnosis, autogenic relaxation, and quiet rest on selected affective states and metabolism. The influence of body position (seated vs. supine) on these same outcome measures was also investigated. Anxiety, tension, and overall mood were assessed before and 30 minutes after each treatment, and oxygen uptake was measured continuously. State anxiety, tension, and a general measure of mood were reduced significantly following each intervention, but oxygen uptake did not change with the exception of small, transient alterations during the physical challenges performed in the hypnosis condition. It is concluded that administration of a routine hypnosis induction to healthy individuals results in a reduction of state anxiety and an improvement of mood commensurate with effects achieved by autogenic training and quiet rest, and these effects occur in both the supine and seated position.