The DIFFMASK score for predicting difficult facemask ventilation: a cohort study of 46,804 patients

Facemask ventilation is an essential part of airway management. Correctly predicting difficulties in facemask ventilation may reduce the risk of morbidity and mortality among patients at risk. We aimed to develop and evaluate a weighted risk score for predicting difficult facemask ventilation during anaesthesia. We analysed a cohort of 46,804 adult patients who were assessed pre-operatively airway for 13 predictors of difficult airway management and subsequently underwent facemask ventilation during general anaesthesia. We developed the Difficult Facemask (DIFFMASK) score in two consecutive steps: first, a multivariate regression analysis was performed; and second, the regression coefficients of the adjusted regression model were converted into a clinically applicable weighted point score. The predictive accuracy of the DIFFMASK score was evaluated by assessment of receiver operating characteristic curves. The prevalence of difficult facemask ventilation was 1.06% (95%CI 0.97–1.16). Following conversion of regression coefficients into 0, 1, 2 or 3 points, the cumulated DIFFMASK score ranged from 0 to 18 points and the area under the receiver operating characteristic curve was 0.82. The Youden index indicated a sum score ≥ 5 as an optimal cut-off value for prediction of difficult facemask ventilation giving a sensitivity of 85% and specificity of 59%. The DIFFMASK score indicated that a score of 6–10 points represents a population of patients who may require heightened attention when facemask ventilation is planned, compared with those patients who are obviously at a high- or low risk of difficulties. The DIFFMASK score may be useful in a clinical context but external, prospective validation is needed.     

高频部分液体通气对吸入伤犬呼吸循环功能的影响

目的　观察高频部分液体通气 (highfrequencypartialliquidventilation ,HFPLV)对吸入性损伤犬肺力学、氧合和血流动力学参数的影响。　方法　 16条犬经吸入蒸气 ,造成重度吸入性损伤模型 ,并随机分为对照组和治疗组。两组动物致伤后均行高频喷射通气 (highfrequencyjetventila tiot,HFJV) ,治疗组同时经气管导管缓慢注入氟碳液体 (3ml/kg体重 ) ,行HFPLV治疗 ,于通气后3 0、60和 90min时测定两组动物血气、肺顺应性、气道阻力及血流动力学参数。　结果　治疗组PaO2 呈进行性上升 ,在各时相点与致伤后比较差异有显著性意义 (P <0 .0 5 ) ,而对照组各时相点与致伤后比较差异无显著性意义 (P >0 .0 5 ) ;治疗组PaCO2 也逐渐增高 ,于 60、90min显著高于致伤后水平 (P <0 .0 5 )。与对照组比较 ,治疗组各时相点的PaO2 稍有升高 (P >0 .0 5 ) ,PaCO2 于 90min显著增高 (P <0 .0 5 ) ,而两组动 /静态气道阻力、肺顺应性和血流动力学参数比较 ,差异均无显著性意义 (P >0 .0 5 )。　结论　HFPLV与单纯HFJV相比 ,更有利于吸入性损伤的动脉氧合 ,对血流动力学参数无明显不利影响     

部分液体通气对吸入性损伤犬的研究

目的 观察部分液体通气(PLV)对吸人性损伤犬呼吸力学、氧合和血流动力学参数的影响.方法 16条健康杂种犬经蒸气吸人造成重度吸入性损伤模型,随机分为对照组和实验组(n=8).实验组经气管导管缓慢注入氟碳液体(12ml/kg体重)行PLV治疗,治疗后30、60、90 min时测定两组犬血气、气道阻力、肺顺应性及血流动力学参数.结果 实验组Pa02呈进行性上升,在各时点与致伤后60 min比较差异有统计学意义(P＜0.05).与对照组比较,实验组各时点的PaO2稍有升高(P＞0.05).两组气道阻力、肺顺应性和血流动力学参数比较,差异均无统计学意义(P＞0.05).结论 PLV有利于吸入性损伤犬的动脉氧合,对血流动力学无明显不利影响.     

Hemodynamic effects of synchronized high-frequency jet ventilation compared with low-frequency intermittent positive-pressure ventilation after myocardial revascularization

BACKGROUND: The purpose of this prospective study was to examine the effect on cardiac performance of selective increases in airway pressure at specific points of the cardiac cycle using synchronized high-frequency jet ventilation (sync-HFJV) delivered concomitantly with each single heart beat compared with controlled mechanical ventilation in 20 hemodynamically stable, deeply sedated patients immediately after coronary artery bypass graft. METHODS: Five 30-min sequential ventilation periods were used interspersing controlled mechanical ventilation with sync-HFJV twice to control for time and sequencing effects. Sync-HFJV was applied using a driving pressure, which generated a tidal volume resulting in gas exchanges close to those obtained on controlled mechanical ventilation and associated with the maximal mixed venous oxygen saturation. Hemodynamic variables including cardiac output, mixed venous oxygen saturation and vascular pressures were recorded at the end of each ventilation period. RESULTS: The authors found that in 20 patients, hemodynamic changes induced by controlled mechanical ventilation and by sync-HFJV were similar. Cardiac index did not change (mean +/- SD for controlled mechanical ventilation: 2.6 +/- 0.7 l x min(-1) x m(-2); for sync-HFJV: 2.7 +/- 0.7 l x min(-1) x m(-2); P value not significant). This observation persisted after stratification according to baseline left-ventricular contractility, as estimated by ejection fraction. CONCLUSIONS: The authors conclude that after coronary artery bypass graft, if gas-exchange values are maintained within normal range, sync-HFJV does not result in more favorable hemodynamic support than controlled mechanical ventilation. These findings contrast with the beneficial effects of sync-HFJV, resulting in marked hypocapnia, on cardiac performance observed in patients with terminal left-ventricular failure.     

Combined-electrostimulation-hypalgesia in surgery of the lumbar vertebral column. A tentative evaluation of this method (author's transl)]

A new concept of anaesthesia in patients undergoing operations of the lumbar vertebral column is presented. Electrostimulation of four auricular acupuncture points is combined with controlled ventilation of nitrous-oxide oxygen mixture. This combination is comparable to similar anaesthesia procedures of other operative fields. In 30 patients the anaesthesia was performed as a "combined electrostimulationhypalgesia". In a control study of 30 similar patients a mixture of nitrous-oxide and oxygen only was used. For 120 min systolic and diastolic blood pressure as well as heart rate of both groups are measured and compared. The postoperative state as well as individual data from the patients are included in the investigation. The analgesia established by "combined electrostimulationhypalgesia" seems to be based essentially on the effect of nitrous-oxide as well as premedication, induction of anaesthesia, relaxation and kind of ventilation. Electrostimulation of auricular acupuncture points seems to induce stabilisation of the circulatory system. On account of our findings the relevance of electrostimulation in this method of anaesthesia must be judged very critically.     

Double frequency jet ventilation for endolaryngeal laser surgery

There are a large number of ventilation methods for endolaryngeal laser microsurgery but unfortunately all have their drawbacks. From December 1990 to August 1992 the authors performed 57 operations using intratracheal (infraglottic) jet ventilation with specially designed equipment. The patients' tracheae were translaryngeally intubated with small bore double-lumen copper pipes and ventilation of the lungs commonly performed either with manually controlled oxygen jets or our variant of high frequency jet ventilation (HFJV), the so-called double frequency jet ventilation (DFJV). In this ventilation mode we added the conventional inflation of the lungs to basic HFJV (most often 3 Hz). This was achieved by creating the auto-PEEP, with cyclic variation of I:E ratio from 1:9 to 9:1. Surgical conditions in all cases were rated good. There were no serious complications. Important points for the avoidance of barotrauma, the most dangerous complication in these ventilation methods, are discussed extensively below.     

Postoperative sedation and analgesia after pediatric liver transplantation

The goal of sedation in the pediatric intensive care unit (PICU) is to produce a calm and comfortable child, free from pain and discomfort. Children receiving liver transplantation need analgesics to control pain from surgical incisions, drains, vascular access, or endotracheal suctioning. Sedatives are used to facilitate the delivery of nursing care, to prevent self-extubation, and to facilitate mechanical ventilation. Optimal sedation produces a state in which the patient is somnolent, responsive to the environment but untroubled by it, and with no excessive movements. A common problem in the PICU is the fluctuation in the delivery of sedatives and analgesics depending on the health care providers and on a breakdown in communication between physicians and nurses to define end points for pharmacological therapy. This variability more often leads to oversedation rather than undersedation. Oversedation delays extubation, promotes ventilator-associated pneumonia, and increases the risk of reintubation. The use of written sedation policies to guide practice at the bedside reduces the length of time for which patients require mechanical ventilation and the length of PICU stay. Protocols for drug administration practices increase patient safety during mechanical ventilation, promote nursing autonomy, and facilitate communication between nurses and physicians as well as between nurses.     

Advances in the management of acute respiratory distress syndrome: protective ventilation

The approach to mechanical ventilation has been revolutionized by new insights into the pathogenesis of respiratory failure in acute respiratory distress syndrome (ARDS). Concepts such as low-volume ventilation, permissive hypercapnia, inverse ratio ventilation, best and intrinsic positive end-expiratory pressure, airway shear, pressure volume curves, inflection points, and prone positioning have radically transformed thinking about ventilator management. Since 1966, more than 8000 ARDS-related publications have appeared. Studies highlighting the experimental basis for innovations in mechanical ventilation are presented. Selected clinical series that exemplify the use of these new strategies are reviewed, to demonstrate how key experimental and clinical research has altered our understanding about what works, and why. Mismanagement of mechanical ventilation causes lung injury and increases mortality. The strategy of protective ventilation has provided the first substantial reduction of mortality in the history of ARDS.     

A study assessing the potential benefit of continued ventilation during cardiopulmonary bypass

It has been suggested that maintaining ventilation during bypass might reduce lung injury, which is a common complication of cardiac surgery. In order to assess this, a study is being undertaken to examine the effect upon a number of parameters that may be indicative of lung injury, of continued ventilation compared with discontinued ventilation whilst on bypass. The following parameters have been assessed: extravascular lung water, static and dynamic compliance, ratio of left atrial/right atrial white blood count, alveolar arterial oxygen gradient and the respiratory index together with clinical end points. Provisional results are reported. Twenty-three elective patients for coronary artery surgery have to date been randomised to either ventilation (VB) (n=12) or non-ventilation on bypass (NVB) (n=11). The post-bypass extravascular lung water was significantly smaller in the VB group compared to the NVB group (530+/-50 ml vs. 672+/-32 ml; P=0.028). Extubation time was also significantly shorter in the VB group (3.6+/-0.3 h vs. 4.8+/-0.4 h; P=0.038). The provisional results of this work in progress are suggestive that continued ventilation during bypass may reduce lung injury.     

Hemodynamic Effects of Synchronized High-frequency Jet Ventilation Compared with Low-frequency Intermittent Positive-pressure Ventilation after Myocardial Revascularization

Background: The purpose of this prospective study was to examine the effect on cardiac performance of selective increases in airway pressure at specific points of the cardiac cycle using synchronized high-frequency jet ventilation (sync-HFJV) delivered concomitantly with each single heart beat compared with controlled mechanical ventilation in 20 hemodynamically stable, deeply sedated patients immediately after coronary artery bypass graft.

Methods: Five 30-min sequential ventilation periods were used interspersing controlled mechanical ventilation with sync-HFJV twice to control for time and sequencing effects. Sync-HFJV was applied using a driving pressure, which generated a tidal volume resulting in gas exchanges close to those obtained on controlled mechanical ventilation and associated with the maximal mixed venous oxygen saturation. Hemodynamic variables including cardiac output, mixed venous oxygen saturation and vascular pressures were recorded at the end of each ventilation period.

Results: The authors found that in 20 patients, hemodynamic changes induced by controlled mechanical ventilation and by sync-HFJV were similar. Cardiac index did not change (mean +/- SD for controlled mechanical ventilation: 2.6 +/- 0.7 l [middle dot] min-1 [middle dot] m-2; for sync-HFJV: 2.7 +/- 0.7 l [middle dot] min-1 [middle dot] m-2;P value not significant). This observation persisted after stratification according to baseline left-ventricular contractility, as estimated by ejection fraction.     

面罩双水平气道正压无创通气在腹腔镜胆囊切除术中的应用

【摘要】〓目的〓探讨面罩双水平气道正压(BiPAP)无创通气在腹腔镜胆囊切除手术全身麻醉中应用的安全可行性。方法〓40例行腹腔镜胆囊切除手术的患者,随机分为面罩BiPAP通气组(I组)和气管内插管间歇正压通气(IPPV)组(Ⅱ组),每组20例,术中监测平均动脉血压(MAP)、心率(HR)、脉搏血氧饱和度(SpO₂)以及Narcotrend指数(NI),并在麻醉前(T0)、麻醉诱导后(T₁)、插管或上面罩后(T₂)、机械通气后5 min(T₃)、气腹后5 min(T₄)、手术结束(T₅)、拔管或去面罩后(T₆)时点记录其数值;两组患者在T₀、T₃、T₄、T₅时点做血气分析,记录PaO₂、PaCO₂、pH值。结果〓I组MAP、HR在T₂和T₆时点低于Ⅱ组(P<0.05),而I组NI在T₁时点高于Ⅱ组(P<0.05);组内比较Ⅱ组在T₂、T₆时点MAP、HR显著升高(P<0.05),而I组在这两个时点无变化。PaO₂、PaCO₂、pH值在T₀、T₃、T₄、T₅时点组间比较差异均无统计学意义。结论〓面罩BiPAP无创通气应用于腹腔镜胆囊切除手术全身麻醉能够进行有效通气,且能维持患者血流动力学平稳,是一种安全有效的通气方式。     

可调节型提下颌麻醉面罩在自主通气全身麻醉中的应用

目的 对比可调节型提下颌麻醉面罩与喉罩在自主通气全身麻醉中的应用.方法 选择行疝修补手术、妇科外阴手术、宫腔镜手术、肛门痔瘘手术等自主通气全身麻醉手术患者100例,按随机数字表法分为面罩组和喉罩组,每组50例.记录两组患者麻醉诱导前(T0)、放置面罩或喉罩前1 min(T1)、放置面罩或喉罩即刻(T2、切皮时(T3)、拔除面罩或喉罩前1 min(T4)、拔除面罩或喉罩即刻(T5)时的MAP、HR、吸气峰压(peak inspiratory pressure,PIP)、PETCO2、SpO2等,记录插入喉罩或可调节型提下颌麻醉面罩的时间和一次成功率,记录患者清醒时间和改良Aldrete评分达到9分时间,观察术后24 h内患者的并发症.结果 可调节型提下颌麻醉面罩与喉罩在两组患者中均成功置入,面罩组各时点间HR和MAP差异均无统计学意义,喉罩组T2时点HR和MAP明显高于T1、T3时点(P＜0.05),T5时点HR和MAP明显高于T0、T4时点(P＜0.05);SpO2、PETCO2、PIP、患者苏醒时间以及改良Aldrete评分达到9分时间在两组之间差异无统计学意义;支气管痉挛、术后咽痛发生率两组之间差异无统计学意义.结论 可调节型提下颌麻醉面罩在自主通气全身麻醉中置入成功率较高,术后并发症较少,是一种安全、有效的呼吸道管理工具.     

Aktuelle Konzepte der unterstützten Spontanatmung

The use of augmented spontaneous breathing is an important component in a bundle concept of weaning from mechanical ventilation as it was demonstrated that controlled ventilation with diaphragmatic underuse induces rapid muscle atrophy and impairs successful weaning. On the other hand spontaneous breathing is often associated with disturbed patient-ventilator interaction resulting in asynchrony (e.g. ineffective triggering, early termination of inspiration and overflow or underflow). It was shown that asynchrony can impair gas exchange, increase work of breathing and enhance deleterious aspects of mechanical ventilation. Concepts of assisted breathing, such as proportional assist ventilation (PAV), adaptive support ventilation (ASV) and neurally adjusted ventilatory support (NAVA), which are intended to increase effort-adapted spontaneous breathing by an electronic or physiological closed loop feedback system with the patient’s work of breathing were developed more than 20 years ago and are currently experiencing a renaissance. It was shown in some smaller clinical investigations that these newer modes are able to improve patient-ventilator interaction, to reduce the burden on respiratory muscles and to increase ventilation comfort. Although large randomized controlled studies are lacking, effort-adapted modes of augmented breathing will become a routine part in the management of weaning from mechanical ventilation.     

Neonatal ventilation

Preventing ventilation-induced lung injury and bronchopulmonary dysplasia is an important goal in the care of ventilated neonates. Recently, there have been tremendous efforts to improve ventilation strategies, which aim at ventilating with a 'protective' and 'open-lung' strategy. Several different ventilation modes are now available, but it is important to note that, with regard to the neonatal pulmonary and neural outcome, there is still no clear evidence as to the superiority of one ventilation mode over another. Clinicians should bear in mind that any ventilation mode used to ventilate a neonate should be accompanied by real-time pulmonary monitoring to continuously adapt the ventilation strategy to the sudden changes in the respiratory mechanical properties of the lung. This article will describe the different ventilation modes available for neonates and highlight the importance of using a protective and open-lung ventilation strategy, even in the operating room.     

Postoperative pulmonary complications and their prevention

Postoperative pulmonary complications are common. Despite advances in perioperative care for patients undergoing major surgery, they are associated with increased morbidity, mortality and healthcare costs. Strategies to reduce postoperative pulmonary complications include identification of patients at risk for respiratory complications, followed by risk stratification and perioperative optimization. This article evaluates current literature on the definition of postoperative pulmonary complications, their underlying biological mechanisms, contributing risk factors and preventative measures. Of note, the wide variability in the definition of postoperative pulmonary complications highlights the importance of identifying outcome measures and standardized end points as they affect the validity of clinical trials. Validated risk prediction models are useful tools for clinicians to stratify patients at risk, however there is still a lack of consensus over which model is the best one to use. Evidence for preventative measures including smoking cessation, correction of anaemia, perioperative respiratory physiotherapy and intraoperative management including lung-protective ventilation and goal-directed haemodynamic therapy are discussed. Most importantly, perioperative care bundles demonstrate the importance of multidisciplinary involvement during different time points when a patient undergoes surgery, and a combination of interventions are found to be more beneficial than individual interventions alone.     

About the quality of prehospital emergency ventilation – a prospective study in trauma patients Eine prospektive Untersuchung an Traumapatienten

Introduction: The prehospitaly initiated endotracheal intubation and controlled ventilation, is especially in multi-system-trauma cases, recognized to be the “gold standard”. Thus especially in view of the increasing demands being placed upon the quality of prehospital emergency treatment in general, the quality of such prehospital induced ventilation, is becoming of increasing importance. Thereby we must take into consideration the limited possabilities, which are afflicted with a high degree of uncertainess, which we have at our disposal to effectively evaluate the efficiency of emergency ventilation. The purpose of our study within a collective of severely traumatized patients, was to determine the quality of prehospitaly induced ventilation with regards to the adequacy of oxygenation and ventilation and as a result of our findings, to identify areas for procedural optimization.     

蒸气吸入伤犬支气管肺泡灌洗后呼吸周期,通气量和血气？…

目的 探讨蒸气吸入性损伤犬支气管肺泡灌洗（ＢＡＬ）后呼吸周期、通气量和血气的变化,以期为临床治疗提供实验依据。方法 将纤维支气管镜楔入伤犬三￣四级肺叶支气管管口,进行小剂量复方药物ＢＡＬ。结果 ＢＡＬ后３０,６０,９０ｍｉｎ的吸气时间（Ｔｉ）和呼吸周期（Ｔｃ）均显著低于对照值（Ｐ〈０．０５）,呼吸率（ＲＲ）均显著高于对照值（Ｐ〈０．０５或Ｐ〈０．０１）;ＢＡＬ后３０￣６０ｍｉｎ内,吸气时每分钟通气     

High frequency pulsation (HFP) enabling tracheo-broncheal suctioning without interrupting mechanical ventilation

A new technique of tracheo-broncheal suctioning is presented which enables constant artificial ventilation with high frequency pulsation (HFP), a modification of high frequency ventilation. Beyond that the high frequency pulsation method permits ventilation of the patient with adjusted end-expiratory pressure. This technique prevents the decrease of arterial oxygen pressure which is usually seen in patients who are disconnected for some time from the respirator as well as during the suction procedure and during periods of decreased end-expiratory pressures.     

The prediction of the need for postoperative mechanical ventilation in patients with myasthenia gravis undergoing transsternal thymectomy

During a sixteen-year period, 51 patients with myasthenia gravis underwent trans-sternal thymectomy including extended resection of the adipose tissue around thymus. Using the criteria of risk factors described by Leventhal and Kimura, a predictive score was assessed for our 51 patients. Leventhal's scoring system achieved an accuracy of 54.3%, a sensitivity of 20.0% and a specificity of 63.9%. And, Kimura's scoring system achieved an accuracy of 75.0%, a sensitivity of 81.8% and a specificity of 73.0%. From this study it was concluded that Kimura's scoring system is statistically more adaptive for Japanese than Leventhal's scoring system, and the Leventhal's accuracy may have increased by adding "bulbar symptoms" and "preoperative crisis" as other risk factors and by decreasing "points" for "duration of myasthenia" and "pyridoxamine dosage", and the "Kimura's " accuracy may have increased by decreasing "7 points" for preoperative crisis. Consequently, patients who received postoperative ventilation were compared with the group who did not, with respect to the 19 factors. Evidence is that Osserman's type, bulbar symptoms, preoperative crisis and preoperative % VC were influenced to require the postoperative ventilation, but sex, age, thymic histology, duration of myasthenia and pyridoxamine dosage were not any influenced to require the postoperative ventilation.