机械通气治疗连枷胸的临床分析

目的 探讨双水平正压通气（biphasic positive airway pressure，BiPAP）在连枷胸中的治疗作用。方法 将我院1999年1月-2005年3月符合连枷胸条件的43例患者，其中14例采用无创正压通气BiPAP模式作为BiPAP组，另外29例患者采用的机械通气模式为常规的间歇正压通气（intermittent positive pressure ventilation，IPPV），作为IPPV组，比较两组的ICU住院时间、并发症、死亡率，以及24、48、72h的动脉血气中的PO2、PCO2与氧合指数。结果 BiPAP组中在ICU中治疗时间比IPPV组明显缩短，并发症、死亡率少于IPPV组。监测24、48、72h的血气分析，PO2、PCO2、PaO2／FiO2差异无显著性。结论 在连枷胸患者的治疗中，BiPAP的机械通气模式优于IPPV。     

双相正压通气治疗急性呼吸窘迫综合征

目的探讨双相气道正压(BIPAP)通气模式治疗急性呼吸窘迫综合征(ARDS)患者的疗效及其对血流动力学和气道力学的影响.方法随机将20例ARDS患者分为BIPAP通气模式组(BIPAP组)和间歇正压通气模式组(IPPV组),行机械通气治疗,每组各10例.观察两组血流动力学、血气分析、呼吸力学指标.结果BIPAP组机械通气时间平均为13天,显著低于IPPV组的21天(P＜0.05).BIPAP组患者安定、吗啡和万可松用量显著低于IPPV组(P＜0.05);IPPV组吸气峰压、平台压和呼气末正压均显著高于BIPAP组(P＜0.05).心率、平均动脉压、平均肺动脉压、体循环阻力和心脏指数两组差别无显著性意义(P＞0.05),但IPPV组肺血管阻力显著高于BIPAP组(P＜0.05).两组间动脉血氧分压、二氧化碳分压和pH值差别无显著性意义(P＞0.05),BIPAP组混合静脉血氧分压显著高于IPPV组(P＜0.05).结论BIPAP通气模式人机关系协同性好,能够降低肺血管阻力,增加混合静脉血氧分压,缩短了ARDS治疗的机械通气时间.     

Comparison of the haemodynamic effects of intermittent positive pressure ventilation with high frequency jet ventilation

The cardiorespiratory effects of intermittent positive pressure ventilation and high frequency jet ventilation with and without positive end expiratory pressure were compared in patients following valvular heart surgery (mitral and/or aortic). Twenty patients received intermittent positive pressure ventilation and high frequency jet ventilation with 0, 0.5 and 1.0 kPa positive end expiratory pressure. High frequency jet ventilation was well tolerated. The addition of 1.0 kPa positive end expiratory pressure was associated with preservation of the arterial oxygen tension without any increase in shunt or significant adverse haemodynamic effect. The results are discussed and compared with a previous study of high frequency jet ventilation following aortocoronary bypass graft surgery.     

间歇正压通气和呼气末正压通气对犬眼内压的影响

目的 探讨间歇正压通气(IPPV)和呼气末正压通气(PEEP)对犬眼内压(10P)的影响.方法 实验犬8只,麻醉后分别监测基础条件下和各种机械通气条件下的IOP、CVP、MAP.结果 实施20 ml/kg和30 ml/kg两种不同潮气量的IPPV时IOP差异无统计学意义.实施10、15、20cm H20三种不同压力值的PEEP时IOP均显著升高(P<0.01).结论 IPPV对IOP影响不大,PEEP可使IOP显著升高.     

无创正压通气治疗全麻拔管后呼吸衰竭

目的 评价无创正压通气(NIPPV)治疗全身麻醉手术拔管后呼吸衰竭的疗效及影响因素.方法 全麻手术拔管后48 h内发生呼吸衰竭的患者34例,应用BiPAP Vision呼吸机实施无创正压通气治疗,比较治疗后避免再插管(成功组)和需要再插管(失败组)患者的基础状态、通气疗效及临床结果,并分析可能的影响因素.结果 无创正压通气使70.6%的术后呼吸衰竭患者避免插管.与失败组相比,成功组心肺并发症所致呼吸衰竭的比例和需要人工辅助吸痰的比例明显低(P<0.05),麻醉药残留呼吸抑制的比例高(P<0.01).结论 无创正压通气治疗全身麻醉手术后呼吸衰竭能够减少再插管率,但可能不适用于存在心肺并发症和排痰障碍的患者.     

Persistent pneumothorax treated with continuous positive airway pressure

A patient who presented with persistent pneumothorax after blunt chest trauma is described. The lung re-expanded partially in response to chest drain suction but some areas remained collapsed. The institution of continuous positive airway pressure on an intermittent basis, was followed by complete re-expansion of the lung and resolution of the pneumothorax.     

The Downs'' adjustable flow generator

A venturi powered device for the generation of continuous positive airways pressure has been assessed. Some of its functional characteristics appear to be ideal, but the oxygen concentration and adequacy of flows require checking after each adjustment. A positive pressure relief valve and an inlet valve are necessary for the safe use of the system and an airway pressure monitor is recommended.     

Efficacy of the laryngeal tube during intermittent positive-pressure ventilation

We studied the efficacy of the laryngeal tube (VBM, Germany) during intermittent positive-pressure ventilation in 50 patients. After induction of anaesthesia and neuromuscular blockade, a size 4 laryngeal tube was inserted for patients of height 155 cm or greater. After insertion of the laryngeal tube, its pharyngeal and oesophageal balloons were inflated to an intracuff pressure of 60 cmH(2)O. An Ambu self-inflating bag was attached to the laryngeal tube and the lungs were ventilated manually at 15 breath.min(-1). It was possible to ventilate the lungs at the first attempt in 47 patients (94%). The airway pressure at which air leaked around the laryngeal tube exceeded 18 cmH(2)O in 41 patients (82%), and was > 30 cmH(2)O in 25 (50%). Median [interquartile range (range)] leak pressure was 30 [20-30 (6 to > 30)] cmH(2)O. Median [interquartile range (range)] tidal volume was 587 [533-653 (133-800)] ml or 8.8 [8.2-10.6 (1.9-12.6)] ml.kg(-1). We conclude that the laryngeal tube has a potential role in airway management during intermittent positive-pressure ventilation for anaesthesia or cardiopulmonary resuscitation.     

Nasopharyngeal airway continuous positive airway pressure: a method to wean from or avoid mechanical ventilation in adults

A simple technique using a nasopharyngeal airway and a continuous positive airway pressure circuit has proved an effective alternative to a tight fitting nasal or face mask for delivery of continuous positive airway pressure. Nasal trauma, discomfort and mouth breathing are the main disadvantages.     

Nasal CPAP reduces systemic blood pressure in patients with obstructive sleep apnoea and mild sleepiness

BACKGROUND: A randomised controlled study was undertaken to examine the effect of nasal continuous positive airway pressure (CPAP) on 24 hour systemic blood pressure (BP) in patients with obstructive sleep apnoea (OSA). METHODS: Patients were fitted with an ambulatory BP measuring device as outpatients during normal activities and recorded for 24 hours before starting therapeutic or subtherapeutic (4 cm H(2)O) CPAP treatment. BP monitoring was repeated before completion of 12 weeks of treatment. The primary end point was the change in 24 hour mean BP. RESULTS: Twenty three of 28 participants in each treatment arm completed the study. There was no significant difference between the two groups in age, body mass index, Epworth Sleepiness Score, apnoea-hypopnoea index, arousal index, and minimum Sao(2). Twenty four patients were hypertensive. The pressure in the therapeutic CPAP group was 10.7 (0.4) cm H(2)O. CPAP usage was 5.1 (0.4) and 2.6 (0.4) hours/night for the therapeutic and subtherapeutic CPAP groups, respectively (p<0.001). After 12 weeks of treatment there were significant differences between the two CPAP groups in mean (SE) changes in 24 hour diastolic BP (-2.4 (1.2) v 1.1 (1.0) mm Hg (95% CI -6.6 to -0.5), p = 0.025); 24 hour mean BP (-2.5 (1.3) v 1.3 (1.1) mm Hg (95% CI -7.2 to -0.2), p = 0.037); sleep time systolic BP (-4.1 (2.1) v 2.2 (1.8) mm Hg (95% CI -11.8 to -0.7), p = 0.028); and sleep time mean BP (-3.6 (1.7) v 1.3 (1.4) mm Hg (95% CI -9.2 to -0.4), p = 0.033). CONCLUSIONS: Compared with subtherapeutic CPAP, 12 weeks of treatment with therapeutic CPAP leads to reductions in 24 hour mean and diastolic BP by 3.8 mm Hg and 3.5 mm Hg, respectively, in mildly sleepy patients with OSA.     

Postoperative CPAP and BiPAP use can be safely omitted after laparoscopic Roux-en-Y gastric bypass

BACKGROUND: Obstructive sleep apnea (OSA) is prevalent in the morbidly obese population. The need for routine preoperative testing for OSA has been debated in bariatric surgery publications. Most investigators have advocated the use of continuous positive airway pressure (CPAP) or bi-level positive airway pressure (BiPAP) in the postoperative setting; however, others have reported pouch perforations or other gastrointestinal complications as a result of their use. From a review of our experience, we present an algorithm for the safe postoperative treatment of patients with OSA without the use of CPAP or BiPAP. METHODS: From January 2003 to December 2007, 1095 laparoscopic Roux-en-Y gastric bypasses were performed at our institution. Preoperative testing for OSA was not routinely performed. A prospective database was maintained. The data included patient demographics, co-morbidities (including OSA and CPAP/BiPAP use), perioperative events, complications, and follow-up information. Patients with known OSA were not given CPAP/BiPAP after surgery. They were observed in a monitored setting during their inpatient stay, ensuring continuous oxygen saturation of >92%. All patients used patient-controlled analgesia, were trained in the use of incentive spirometry, and ambulated within a few hours of surgery. The outcomes were compared between the OSA patients using preoperative CPAP/BiPAP versus those with OSA without preoperative CPAP/BiPAP versus patients with no history of OSA. RESULTS: A total of 811 patients were included in the study group with no known history of OSA. Of the 284 patients with a confirmed diagnosis of OSA, 144 were CPAP/BiPAP dependent. Statistically significant differences were present in age distribution and gender, with men having greater CPAP/BiPAP dependency. No significant differences were found in body mass index, length of stay, pulmonary complications, or deaths. One pulmonary complication occurred in the OSA, CPAP/BiPAP-dependent group, three in the OSA, non-CPAP group, and six in the no-known OSA group. No anastomotic leaks or deaths occurred in the series. CONCLUSION: Postoperative CPAP/BiPAP can be safely omitted in laparoscopic Roux-en-Y gastric bypass patients with known OSA, provided they are observed in a monitored setting and their pulmonary status is optimized by aggressive incentive spirometry and early ambulation.     

Fluctuating CPAP (F-CPAP) versus conventional CPAP (C-CPAP) in dogs with blood aspiration

Fluctuating CPAP(F-CPAP) is a combination of spontaneous ventilation and fluctuating PEEP, in which end-expiratory pressure (EEP) is periodically changed within a certain range. In a dog model with localized lung injury induced by the aspiration of non-heparinized blood (2ml·kg^–1 body weight), we carried out a comparative study of the effects of F-CPAP in which the EEP was cyclically changed from 4 to 12cmH₂O with periods of 10min and those of conventional CPAP with a fixed EEP of 8cmH₂O (C-CPAP), on hemodynamics and pulmonary oxygenation. The blood aspiration produced significant increases in the intrapulmonary shunt ( sp/ t), the alveolar-arterial difference of partial pressure of oxygen (A-aDo ₂), and the respiratory rate (RR). Although both F-CPAP and C-CPAP reduced sp/ t and A-aDo ₂ and RR, 7 dogs treated with F-CPAP showed a significantly greater recovery of sp/ t and A-aDo ₂ than 7 dogs treated with C-CPAP. There were no significant differences in hemodynamic variables between the two groups. These results suggest that F-CPAP is more useful in the treatment of some kinds of hypoxic respiratory failure due to uneven distribution of lung injury.(Sakurada M, Inaba H, Sato J, et al.: Fluctuating CPAP (F-CPAP) versus conventional CPAP (C-CPAP) in dogs with blood aspiration. J Anesth 5: 36–42, 1991)     

The Basle PEEP weaner

A device to modify the physiological impact of the abrupt transition of IPPV and PEEP to spontaneous breathing is described. It consists of a coaxial breathing system with a spring-loaded reservoir bag and underwater pressure limit. Electric alarms are incorporated.     

Use of the Inspiron nebuliser during continuous positive airway pressure ventilation

The Inspiron Nebuliser 002305 with air entrainment was assessed as a gas delivery device in a continuous positive airway pressure system. Inspired oxygen concentrations, total gas flows and pressures within the system were measured over a range of settings, with and without positive and expiratory pressure. Inspired oxygen concentrations and total flows were completely disrupted when a positive and expiratory pressure valve was applied, and the system failed to generate continuous positive airway pressure. We would not therefore recommend the Inspiron nebuliser as a gas delivery system for continuous positive airway pressure.     

Development and Evaluation of a Flow-Dividing Unit for Differential Ventilation and Selective PEEP

Differential ventilation with selective positive end-expiratory pressure (PEEP) was studied in a two-compartment lung model, using one ventilator and a flow-dividing unit consisting of inspiratory flow resistors and an inspiratory threshold valve. The compliance of each lung compartment was varied between 0.15 and 0.23 1 X kPa-1 and the resistance was varied from 0 to 3.5 kPa X 1(-1) X s. The minute volume was 12 1 and the respiratory frequency 12/min, with an inspiratory:expiratory ratio of 1:2. An even distribution of ventilation to the two lung compartments was obtained with the inspiratory flow resistors or the threshold valve under all conditions studied. However, a stepwise increase in the inspiratory resistance of one lung compartment from 1.0 to 2.5 or from 2.5 to 3.5 kPa X 1(-1) X s required readjustment of the inspiratory flow resistor to achieve an even distribution of ventilation, whereas the inspiratory threshold valve needed no readjustment. Large differences in the inspiratory impedance of the two lung compartments caused asynchronous gas delivery when the ventilation distribution was adjusted by means of the flow resistors. Use of the threshold valve resulted in synchronous gas delivery. The flow-dividing unit consists of non-active elements and can thus be connected to any ventilator.     

The effect of positive airway pressure during pre-oxygenation and induction of anaesthesia upon duration of non-hypoxic apnoea

Positive end-expiratory pressure (PEEP) applied during induction of anaesthesia may prevent atelectasis formation in the lungs. This may increase the duration of non-hypoxic apnoea by increasing the functional residual capacity. We studied the benefit of PEEP applied during the induction of anaesthesia on the duration of apnoea until the SpO2 reached 90%. Forty ASA I-II patients were randomly allocated to one of two groups. In the PEEP group (n = 20) patients were pre-oxygenated using 100% O2 administered using a CPAP device (6 cmH2O) for 5 min. Following induction of anaesthesia, patients were mechanically ventilated (PEEP 6 cm H2O) for a further 5 min. In the ZEEP group (n = 20), no CPAP or PEEP was used. The duration of apnoea until SpO2 reached 90% was measured. Non-hypoxic apnoea duration was longer in the PEEP group compared to ZEEP group (599 +/- 135 s vs. 470 +/- 150 s, p = 0.007). We conclude that the application of positive airway pressure during induction of anaesthesia in adults prolongs the non-hypoxic apnoea duration by > 2 min.     

食管引流型喉罩间歇正压通气时头前屈位对气道密封压的影响

Objective To evaluate the influence of head anteflexion on airway sealing pressure during intermittent positive pressure ventilation(IPPV) with ProSeal laryngeal mask airway (PLMA) with an esophageal vent.Methods Fifty ASA Ⅰ or Ⅱ patients (20 males and 30 females), aged 18-51 ye are, weighing 50-70 kg and scheduled for elective plastic surgery under general anesthesia, were enrolled in this study. Anesthesia was induced with fentanyl 2 μg/kg, propofol 2 μg/kg and vecuromium 0.1 mg/kg. PLMA with an esophageal vent was inserted at 2 min after intravenous vecuronium injection.The airway sealing pressure, the anatomic position of the cuff and the efficacy of positive pressure ventilation were checked in the neutral and anteflexed head positions with the cuff deflated and inflated to an intracuff pressure of 60 cm H2 O, respectively.Results The lungs were better ventilated in the head anteflexion position than in the head neutral position whether the cuff was deflated or inflated. There was no significant difference in the volume of air required to achieve an intracuff pressure of 60 cm H2O between the two head positions ( P＞ 0.05). The airway seating pressure increased from (27 ± 6) cm H2O in the head neutral position to (33 ± 6) cm H2O in the head anteflexion position, with no significant difference between them ( P＞ 0.05). The expired tidal volume and the peak inspiratory pressure during IPPV were (496 ± 81 ) ml and (14.3 ± 1.9) cm H2O respectively in the head neutral position and (496 ± 81 ) ml and ( 14.5 ± 2.1 )cm H2O respectively in the head anteflexion position.Conclusion Head anteflexion can significantly improve airway sealing but does not affect the anatomic position of the cuff.Appropriate head anteflexion is a simple and effective way to improve IPPV when the airway sealing pressure is inadequate in the head neutral position.