Practical ventilator management

Mechanical ventilation is a common invasive intervention in intensive care units. While respiratory failure remains the most common indication for mechanical ventilation, the application and indications of this intervention are far more variable. Ventilation causes marked alteration to human physiology and is associated with complications and iatrogenic injuries. This article highlights practical aspects of patient management during invasive ventilation.     

Management of and indications for tracheostomy in care of the critically ill patient

Tracheostomy is a procedure that has evolved over many hundreds of years. In the 21st century, the majority of tracheostomies are now inserted by intensivists in the intensive care unit (ICU). Commonly performed to assist in weaning patients from mechanical ventilation, the procedure is performed using a percutaneous dilatational technique. Percutaneous tracheostomy can generally be performed safely in the ICU, although a number of contra-indications and complications do exist. Recent publications have highlighted weaknesses in the quality of care both in the immediate and longer term. Consequently, a number of organizations, based in the UK and internationally, have turned the focus in recent years to improving the quality of care delivered to these patients. Clinicians caring for patients with tracheostomies should not only be familiar with the indications, anatomy and insertion techniques, but also current guidance on routine care and the emergency management of complications.     

老年重症肺部感染患者血清降钙素原表达水平及对机械通气撤机结局的预测价值

目的观察老年重症肺部感染患者血清降钙素原(PCT)表达水平,探讨其对机械通气撤机结局的预测价值。方法选取重症肺部感染老年患者50例为重症组,轻中重度肺部感染老年患者30例为非重症组,另选取同期体检健康患者30例为对照组。对比3组入院24 h内血清PCT、超敏C反应蛋白(hs-CRP)水平,以及重症组不同病原体感染患者上述指标差异。观察重症组48 h内的撤机结局,分析撤机前血清PCT、hs-CRP和白细胞计数(WBC)水平对撤机结局的预测价值。结果1重症组血清PCT显著高于非重症组和对照组(P0.05)。2重症组细菌性感染30例,病毒性感染13例,支原体感染7例,重症组细菌性感染患者血清PCT和WBC显著高于病毒性感染和支原体感染患者(P0.05),hs-CRP比较差异无统计学意义(P0.05)。3重症组撤机成功39例,撤机失败11例;撤机前血清PCT的ROC曲线下面积为0.812,最佳截点值为0.80 ng/m L,敏感度为82.0%,特异度为76.0%。结论血清PCT可以作为老年重症肺部感染患者的辅助诊断指标,且对患者撤机结局有一定的预测价值。     

智能化撤机和经验性撤机的前瞻性随机对照研究

目的 比较智能化撤机和经验性撤机两种撤机方法对机械通气撤机困难患者的疗效.方法 采用前瞻性随机对照研究,按平衡指数最小的原则进行简易的临床试验随机化分组,将62例综合ICU内的撤机困难患者随机分入智能化Smart Care组(SC组,30例)和同步间歇指令通气联合压力支持通气组(SP组,32例)进行撤机试验,两组患者的疾病构成、年龄、性别、入ICU时急性生理慢性健康状况评分(APACHE)Ⅱ以及撤机前机械通气时间差异均无统计学意义.两组患者除撤机方法不同外,其他处理均相同,观察两组的撤机时间、再插管率和机械通气相关并发症的发生率以及ICU滞留率.结果 SC组神经肌肉病变患者、术后呼吸支持患者和呼吸系统疾病患者的撤机时间分别为(49±13)、(67±37)和(25±96)h,明显少于SP组[分别为(223±38)、(106±34)和(502±91)h,X~2值分别为8.33、4.77和4.43,均P<0.05].SC组神经肌肉病变患者、术后呼吸支持患者的ICU滞留时间分别为(9.0 ±1.7)和(7.3±1.9)d,明显低于SP组的(20.8±5.1)和(14.6±1.7)d(X~2值分别为6.74和7.68,均P<0.05).SC组平均调节呼吸机次数为(5±1)次/人明显低于SP组的(13±3)次/人(t=2.73,P<0.05).两组的再插管率、气管切开率、气胸发牛率、呼吸机相关性肺炎(VAP)发生率和皮下气肿发生率比较差异均无统计学意义.结论 CDW智能化撤机法应用于撤机困难患者能够有效地缩短撤机时间,减少ICU滞留时间,并可以减少医生调节呼吸机的负担而节约医疗资源.     

ICU患者困难撤机的医源性因素分析

目的研究导致ICU患者困难撤机的医源性因素。方法比较2007年3月～2010年3月间我院ICU收治的接受机械通气治疗的患者,分析困难撤机组与成功脱机组患者临床资料。结果困难撤机组患者气管切开率、较细口径导管使用率、呼吸机相关性肺炎发生率、意外拔管率、撤机不当率等明显高于成功脱机组,具有显著统计学意义（P〈0.05）。结论人工气道建立方式、导管口径、院内感染、呼吸机管道的管理、撤机策略等是ICU患者困难撤机的医源性因素。     

机械通气时间对SmartCare/PS脱机功能影响的比较

目的探讨机械通气时间对SmartCare/PS（SC）脱机功能的影响。方法将SC脱机患者分为A（简单脱机）、B（困难脱机、延迟脱机）两组,进行SC实际成功率的比较。对SC提示与实际脱机成功一致组（实际成功组）和SC提示成功但实际脱机失败组（实际失败组）的呼吸力学指标进行比较。结果两组SC实际脱机成功率有统计学意义（P〈0.01）。SC实际失败组的RR快,Vt、MIP等均显著低于SC实际成功组;RSBI各时间段等均高于SC实际成功组,差异有统计学意义（P〈0.01）。结论 SC应用于简单脱机准确率高,而对困难脱机、延迟脱机应用SC脱机准确性偏低,需结合MIP、RSBI的动态变化以提高实际脱机的成功率。     

Phenotypic Plasticity and Function of the Hard Palate in Growing Rabbits

Morphological variation related to differential loading is well known for many craniomandibular elements. Yet, the function of the hard palate, and in particular the manner in which cortical and trabecular bone of the palate respond to masticatory loads, remains more ambiguous. Here, experimental data are presented that address the naturalistic influence of biomechanical loading on the postweaning development and structure of the hard palate. A rabbit model was used to test the hypothesis that variation in the morphology of the hard palate is linked to variation in masticatory stresses. Rabbit siblings were divided as weanlings into soft and hard/tough dietary treatment groups of 10 subjects each and were raised for 15 weeks until subadulthood. MicroCT analyses indicate that rabbits subjected to elevated masticatory loading developed hard palates with significantly greater bone area, greater cortical bone thickness along the oral lamina, and thicker anterior palates. Such diet‐induced levels of palatal plasticity are comparable to those for other masticatory elements, which likely reflect osteogenic responses for maintaining the functional integrity of the palate vis‐à‐vis elevated stresses during unilateral mastication. These data support a role for mechanical loading in the determination of palatal morphology, especially its internal structure, in living and fossil mammals such as the hominin Paranthropus. Furthermore, these findings have potential implications for the evolution of the mammalian secondary hard palate as well as for clinical considerations of human oral pathologies. Anat Rec 2009. © 2008 Wiley‐Liss, Inc.     

42例COPD患者成功脱机的护理

目的：探讨机械通气的慢性阻塞性肺疾病（COPD）患者脱机的指征和护理方法。方法：ICU机械通气的COPD患者42例,呼吸机应用时间14～62天。采用过渡撤机方法,并指导患者进行呼吸肌锻炼,加强心理护理、呼吸道管理及营养支持。结果：38例撤机时间3—7天,平均4．71±1．32天,4例撤机时间〉7d。撤机后经气管插管内吸氧,呼吸、心率、血气分析各项指标稳定,咳嗽有力。结论：熟练应用呼吸机,做好患者心理护理,加强呼吸道管理及营养支持,是保证患者顺利撤机的关键措施。     

The Prediction of Extubation Success of Postoperative Neurosurgical Patients Using Frequency–Tidal Volume Ratios

Background  The process of discontinuing neurological patients from mechanical ventilation is still controversial. The aim of this study was to report the outcome from extubating patients undergoing elective craniotomy and correlate the result with the measured f/V _t ratio. Materials and Methods  In a cohort prospective study, all consecutive patients who required mechanical ventilation for up to 6 h after elective craniotomy were eligible for inclusion in this study. Patients passing daily screening criteria automatically received a spontaneous breathing trial (SBT). Immediately previous to the extubation, the expired minute volume (VE), breathing frequency (f), and tidal volume (V _t) were measured and the breathing frequency-to-tidal volume ratio (f/V _t) was calculated; consciousness level based on Glasgow Coma Scale (GCS) was evaluated at the same time. The extubation was considered a failure when patients needed reintubation within 48 h. Results  Ninety-two patients were extubated and failure occurred in 16%. Despite 15 patients failed extubation just one of them presented the f/V _t score over 105. The best cutoff value for f/V _t observed was 62, but with low specificity (0.53) and negative predictive values (0.29). Area under the ROC curve for the f/V _t was 0.69 ± 0.07 (P = 0.02). Patients who failed the extubation process presented higher incidence of pneumonia (80%), higher need for tracheostomy (33%) and mortality rate of 40%. Conclusion  The f/V _t ratio does not predict extubation failure in patients who have undergone elective craniotomy. Patients who fail extubation present higher incidence of pneumonia, tracheostomy and higher mortality rate.     

Predictors of ventilator weaning in individuals with high cervical spinal cord injury

BACKGROUND/OBJECTIVE: To evaluate which tests best predict the ability of patients with ventilator-dependent tetraplegia to wean from the ventilator. METHODS: Retrospective review of patients. PARTICIPANTS: Twenty-six ventilator-dependent patients with tetraplegia admitted to a university inpatient spinal cord-injury rehabilitation unit with American Spinal Injury Association (ASIA) injury levels C2 to C6, A or B. RESULTS: Failure to wean off the ventilator completely was predicted by absence of motor unit recruitment of one hemidiaphragm or at least moderate decreased recruitment with needle electromyography (EMG) in both hemidiaphragms. Phrenic nerve conduction studies would have predicted that all patients who weaned off the ventilator would have failed. Fluoroscopic examination of the diaphragm and bedside spirometry were not as good predictors of ability to wean, failing to predict accurately in 44% and 19% of cases, respectively. ASIA examination was also not entirely predictive, and any outliers that may have been expected to wean based on ASIA examination (ie, C4 or lower neurological levels) were predicted not to wean by needle electromyography. CONCLUSIONS: Negative inspiration force diaphragm needle EMG best predicted the ability to wean from the ventilator. Bedside spirometry (negative inspiratory force and forced vital capacity) is an accurate bedside measure of a patient's readiness to wean. Fluoroscopic examination of the diaphragm and phrenic nerve conduction studies were not helpful in determining weaning potential in ventilator-dependent patients with cervical spine injury.