PEEP在COPD呼吸衰竭机械通气治疗中的应用体会

目的研究PEEP在COPD呼吸衰竭机械通气治疗中的利弊.方法将48例COPD呼吸衰竭上机患者按是否加用PEEP分为2组,分别记录两组患者通气前后血气变化、气压伤发生率以及通气时间长短,进行分析比较.结果加用PEEP组的氧合改善显著、通气时间明显缩短、气压伤的发生率两组比较无显著差异性.结论加用低水平PEEP对COPD呼吸衰竭上机患者的治疗有益无害.     

Anesthesia systems. Part 1: Operating principles of fundamental components

This article is the first in a two-part series on the operation of principal components within Narkomed anesthesia systems. Part 1 illustrates the structure and function of various sections of the machine's internal piping, including components of the pneumatic circuit and the oxygen flush valve, and several safety features, such as the oxygen supply pressure alarm, oxygen failure protection device, and oxygen ratio monitor controller. The article progresses to other basic components of the anesthesia system. Topics include the function of the absorber unit and the flow of gas through it, the principle of operation of the positive end-expiratory pressure valve, the function and mechanics of the adjustable pressure limiter valve, and the open reservoir scavenger system. Part 1 is a valuable tool in understanding the function and pneumatics of the primary components of the anesthesia system.All figures are compliments of the Department of Education at North American Dräger, Telford, PA.     

Performance characteristics of 10 home mechanical ventilators in pressure-support mode: a comparative bench study

OBJECTIVE: Inspiratory pressure (Pi) support delivered by a bilevel device has become the technique of choice for noninvasive home ventilation. Considerable progress has been made in the performance and functionality of these devices. The present bench study was designed to compare the various characteristics of 10 recently developed bilevel Pi devices under different conditions of respiratory mechanics. DESIGN: Bench model study. SETTING: Research laboratory, university hospital. MEASUREMENTS: Ventilators were connected to a lung model, the mechanics of which were set to normal, restrictive, and obstructive, that was driven by an ICU ventilator to mimic patient effort. Pressure support levels of 10 and 15 cm H(2)O, and maximum were tested, with "patient" inspiratory efforts of 5, 10, 15, 20, and 25 cm H(2)O. Tests were conducted in the absence and presence of leaks in the system. Trigger delay, trigger-associated inspiratory workload, pressurization capabilities, and cycling were analyzed. RESULTS: All devices had very short trigger delays and triggering workload. Pressurization capability varied widely among the machines, with some bilevel devices lagging behind when faced with a high inspiratory demand. Cycling was usually not synchronous with patient inspiratory time when the default settings were used, but was considerably improved by modifying cycling settings, when that option was available. CONCLUSIONS: A better knowledge of the technical performance of bilevel devices (ie, pressurization capabilities and cycling profile) may prove to be useful in choosing the machine that is best suited for a patient's respiratory mechanics and inspiratory demand. Clinical algorithms to help set cycling criteria for improving patient-ventilator synchrony and patient comfort should now be developed.     

Methods of management of flail chest

We have treated 30 patients with flail chest, with priority given to associated factors (pain, secretions retention, hemo-/pneumothorax and underlying pulmonary contusion). When this treatment was insufficient IMV+PEEP was instituted; in this group there was a 58.8% incidence of pneumonia, 47.5% of sepsis and 11.7 days average stay in the ICU. These were significantly different when compared to the patients controlled without mechanical ventilatory support (7.7% pneumonia, 0% sepsis, 3.2 days).Surgical fixation was limited to 4 patients who presented with multiple and greatly displaced rib fractures, which made fixation by mechanical ventilation unpredictable.     

Elimination of ventilator dead space during synchronized ventilation in premature infants

BACKGROUND: Mainstream airflow sensors used in neonatal ventilators to synchronize mechanical breaths with spontaneous inspiration and measure ventilation increase dead space and may impair carbon dioxide (CO(2)) elimination. OBJECTIVE: To evaluate a technique consisting of a continuous gas leakage at the endotracheal tube (ETT) adapter to wash out the airflow sensor for synchronization and ventilation monitoring without CO(2) rebreathing in preterm infants. DESIGN: Minute ventilation (V'(E)) by respiratory inductance plethysmography, end-inspiratory and end-expiratory CO(2) by side-stream microcapnography, and transcutaneous CO(2) tension (TcPCO(2)) were measured in 10 infants (body weight, 835+/-244 g; gestational age, 26+/-2 weeks; age, 19+/-9 days; weight, 856+/-206 g; ventilator rate, 21+/-6 beats/min; PIP, 16+/-1 centimeters of water (cmH(2)O); PEEP, 4.2+/-0.4 cmH(2)O; fraction of inspired oxygen (FIo(2)), 0.26+/-0.6). The measurements were made during four 30-minute periods in random order: IMV (without airflow sensor), IMV+Sensor, SIMV (with airflow sensor), and SIMV+Leak (ETT adapter continuous leakage). RESULTS: Airflow sensor presence during SIMV and IMV+Sensor periods resulted in higher end-inspiratory and end-expiratory CO(2), Tcpco(2), and spontaneous V'(E) compared with IMV. These effects were not observed during SIMV+Leak. CONCLUSIONS: The significant physiologic effects of airflow sensor dead space during synchronized ventilation in preterm infants can be effectively prevented by the ETT adapter continuous leakage technique.     

外伤性ARDS病人应用PEEP的监护

急性呼吸窘迫综合征 (ARDS)是以急性呼吸窘迫、顽固性低氧血症为特征 ,以肺顺应性降低、双肺弥漫性浸润性改变为病理基础的急性缺氧性呼吸衰竭。预后不良 ,病死率高。我院2 0 0 0年 3月至 2 0 0 1年 3月共收治 8例 ARDS病人。死亡 2例 ,病死率为 2 5 % ,明显低于文献报道 (病死率为 5 0 %～ 6 0% ) [1 ] ,在临床监护中我们的体会如下。1　一般资料本组 8例病人 ,男 6例 ,女 2例 ,年龄在 31岁～ 5 8岁。其中因交通事故伤 6例 ,坠落伤 2例。本组 8例病人均合并 ARDS,除 2例合并脑挫裂伤、休克死亡外 ,其余均治愈出院。2　监护体会2 .1　…     

Differential lung ventilation with a double-lumen tracheostomy tube in unilateral refractory atelectasis

Two patients with refractory hypoxemia due to unilateral lung atelectasis were treated with differential lung ventilation (DLV) through a Robertshaw-type, double-lumen tracheostomy tube. DLV was applied using two non-synchronized ventilators and maintained for 6 and 3 days, respectively. Ventilator settings were chosen in accord to the clinical, laboratory and chest X-rays results. Particularly, tidal volume and PEEP were set to avoid excessively high alveolar pressure and to obtain the highest possible value of compliance. We investigated the mechanical properties of the two lungs separately by measuring airway pressure and compliance of each lung before the beginning of DLV and at 0, 5, 24, and 48 h after. Initially we observed in both patients very low values of compliance (7–9 cm H₂O/I) and a significant level of PEEPi (12–8 cm H₂O) of the diseased lung, whereas PEEPi in the healthy lung was negligible. The clinical improvement was assessed by sequential chest X-rays and by significant improvement of arterial blood gas and PaO₂/FiO₂ ratios and was associated with a progressive increase of compliance (24–22 cm H₂O/I) and by a fall of PEEPi levels (5–4 cm H₂O) of the diseased lung. We also observed an improvement of S O₂, O₂AVI, PVRI and va/ t values (Case 1). The tracheostomy tube used to apply DLV was very reliable, allowing easy nursing care and selective bronchial aspirations. We conclude that DLV is a very useful technique in unilateral lung pathology, and it can be a life saving procedure in selected patients, by supplying volume and PEEP more efficiently to the affected lung.     

肺保护性机械通气和传统机械通气治疗新生儿急性呼吸衰竭临床观察

目的观察传统机械通气和肺保护性机械通气治疗新生儿急性呼吸衰竭的临床情况。方法选择40例急性呼吸衰竭新生儿患儿，随机分为两组，A组用传统机械通气，B组用肺保护性机械通气。A组潮气量（VT）10～12ml／kg，气道峰压（PIP）〈25cmH2O，呼气末正气（PEEP）（5．0±1．5）cmH2O，呼吸频率（RR）60次／min；B组VT为5～8ml／kg，PEEP为（7．6±1．5）cmH2O，RR为40～60次／分。结果转归比较：两组所有病人均治愈。呼吸机参数比较：两组在维持SaO2在90％以上且PaCO2〈8．0kPa的呼吸机各项参数，A组的VT（10．11±1．20）ml／kg、PIP（24．01±2．10）cmH2O、PEEP（7．50±1．50）cmH2O，两组VT、PIP差异有非常显著性（P〈0．01），两组PEEP的差异无显著性（P〉0．05）。血气比较：pH值A组7．35±0．10，B组7．25±0．15；PaCO2为A组（6．90±0．72）kPa，B组（93．0±2.8）kPa；两组pH、PaCO2、SaCO2（％）值比较差异均无显著性（P均〉0．05）。两组并发症比较：A组肺损伤4例，循环系统并发症3例，B组无。结论传统策略和肺保护性策略通气均能治愈新生儿急性呼吸衰竭，但后者并发症较少。在维持PH、PaCO2、PaO2、SaO2基本相同的情况下，肺保护性通气的呼吸机参数VT和PIP较传统通气明显降低。     

Dynamic measurement of intrinsic PEEP does not represent the lowest intrinsic PEEP

Objective: Dynamic intrinsic PEEP (PEEPi-dyn) is the airway pressure required to overcome expiratory flow and is considered to represent the lowest regional PEEPi. However, there are few data to validate this assumption. We investigated if PEEPi-dyn represents the lowest PEEPi. Setting: The animal laboratory at the Osaka University Medical School. Measurements and results: We compared static PEEPi (PEEPi-stat) and PEEPi-dyn in healthy animals. Five adult white rabbits (2.77 ± 0.05 kg) were anesthetized, tracheostomized, and intubated with several different sizes of endotracheal tubes (ETT) (2.0, 2.5, 3.0, 3.5, or 4.0 mm i. d.). The animals were paralyzed and ventilated (Siemens Servo 900C). Baseline ventilator settings were at a rate of 50/min, inspiratory:expiratory (I:E) ratio of 2:1 or 4:1, and minute ventilation was manipulated to create 3 or 5 cm H₂O PEEPi-stat. PEEPi-stat was measured using the expiratory hold button of the ventilator. PEEPi-dyn showed large variations. In all ventilator settings, PEEPi-dyn was higher than PEEPi-stat (p < 0.001). The larger the ETT, the higher the PEEPi-dyn at an I:E ratio of 2:1 (p < 0.05). The higher the minute ventilation, the greater the difference between PEEPi-stat and PEEPi-dyn. The tidal volume and the difference showed a significant correlation (r ² = 0.514, p < 0.001). Conclusions: The value of PEEPi-dyn was dependent on ventilatory settings, and PEEPi-dyn does not necessarily represent the lowest regional PEEPi within the lungs. Received: 27 April 1998 Final revision received: 18 November 1998 Accepted: 20 November 1998