Continuous positive airway pressure (CPAP) vs. intermittent mandatory pressure release ventilation (IMPRV) in patients with acute respiratory failure

Intermittent Mandatory Pressure Release Ventilation (IMPRV) is a positive pressure spontaneous breathing ventilatory mode in which airway pressure is released intermittently and synchronously with patient's spontaneous expiration in order to provide ventilatory assistance. Eight critically ill patients free of any factor known to alter chest wall mechanics (group 1) and 8 critically ill patients whose spontaneous respiratory activity was markedly altered by a flail chest, or by a C₅ quadraplegia and/or by the administration of opioids (group 2) were studied prospectively. CPAP and IMPRV were administered to each patient in a random order during a 1 h period using a CESAR ventilator. Gas flow, tidal volume, tracheal pressure, esophageal pressure, end-expiratory lung volume and hemodynamic parameters were measured. In group 1 patients, the ventilatory assistance provided by IMPRV was associated with a significant decrease in spontaneous tidal volume whereas all other respiratory parameters remained unchanged. In group 2 patients, IMPRV increased minute ventilation from 8.0±2.61/min to 12.2±1.81/min (p<0.05), decreased PaCO₂ from 46±7.3 mmHg to 38±6.8 mmHg (p<0.05) and reduced respiratory frequency from 21±10 bpm to 14±5.7 bpm (p<0.07). These results show that IMPRV provides significant ventilatory assistance to patients with mild acute respiratory failure either by decreasing patient's contribution to minute ventilation or by increasing alveolar ventilation in presence of respiratory depression of central or peripheral origin.Presented in part at the 32th Congrès National d'Anesthésie-Réanimation, Paris, September, 24, 1990 and at the Annual Meeting of the American Society of Anesthesiologists, Las Vegas, Nevada, October 22, 1990     

Effect of continuous oxygen insufflation on induced-gastric air volume during cardiopulmonary resuscitation in a cadaveric model

BackgroundThe main objective of this study was to compare the volume of gas insufflated in the stomach with continuous external chest compressions plus continuous oxygen insufflation (C-CPR) versus standard-CPR (S-CPR) which alternates external chest compressions and synchronized positive insufflations through a bag-valve-mask with a 30/2 ratio. The secondary objective was to compare upper airway pressures (intratracheal and intramask) generated during continuous oxygen insufflation.Material and methodsOpen, prospective, randomized, cross over, comparative, non-inferiority study. CPR was performed for six minutes periods, on seven fresh human corpses, with C-CPR or S-CPR in a random order. Before each CPR period, the stomach was completely emptied through the gastrostomy tube, and then 200 mL of air was injected in the stomach to be sure it was not collapsed. The gastric volume was measured at the end of each intervention. Intratracheal and intramask pressures were recorded continuously during C-CPR. Results were provided as mean ± standard deviation. Statistical analyses were done with a paired student t test.ResultsInduced-gastric inflation was lower with C-CPR (221 ± 130 mL) than with S-CPR (5401 ± 2208 mL, p = 0.001). Throughout C-CPR, no difference was found between the intratracheal and intramask pressures (4.4 ± 1.2; 4.0 ± 0.8 cmH₂O, respectively, p = 0.45).ConclusionThis human cadaver study demonstrates that continuous oxygen insufflation induced less gastric inflation than intermittent insufflation during CPR.     

Continuous positive airway pressure vs. proportional assist ventilation for noninvasive ventilation in acute cardiogenic pulmonary edema

Objective To compare continuous positive airway pressure (CPAP) and proportional assist ventilation (PAV) as modes of noninvasive ventilatory support in patients with severe cardiogenic pulmonary edema. Design and setting A prospective multicenter randomized study in the medical ICUs of three teaching hospitals. Patients Thirty-six adult patients with cardiogenic pulmonary edema (CPA) with unresolving dyspnea, respiratory rate above 30/min and/or SpO₂ above 90% with O₂ higher than 10 l/min despite conventional therapy with furosemide and nitrates. Interventions Patients were randomized to undergo either CPAP (with PEEP 10 cmH₂O) or PAV (with PEEP 5–6 cmH₂O) noninvasive ventilation through a full face mask and the same ventilator. Measurements and results The main outcome measure was the failure rate as defined by the onset of predefined intubation criteria, severe arrythmias or patient's refusal. On inclusion CPAP (n = 19) and PAV (n = 17) groups were similar with regard to age, sex ratio, type of heart disease, SAPS II, physiological parameters (mean arterial pressure, heart rate, blood gases), amount of infused nitrates and furosemide. Failure was observed in 7 (37%) CPAP and 7 (41%) PAV patients. Among these, 4 (21%) CPAP and 5 (29%) PAV patients required endotracheal intubation. Changes in physiological parameters were similar in the two groups. Myocardial infarction and ICU mortality rates were strictly similar in the two groups. Conclusions In the present study PAV was not superior to CPAP for noninvasive ventilation in severe cardiogenic pulmonary edema with regard to either efficacy and tolerance. T. Rusterholtz and P.-E. Bollaert contributed equally to this study. This work was supported in part by Respironics Inc., Murrysville, PA, USA.     

老年患者施行不同通气模式对单肺通气氧合及气道压力的影响

目的观察老年患者胸科手术时单肺通气期间不同通气模式对患者气道压力和氧合的影响。方法需行单肺通气麻醉的老年手术病人120例,其中男性80例,女性40例,年龄60岁以上。将120名患者分为例组,施行全麻诱导双腔插管后行双肺通气,进胸后分别再进行不同通气模式的单肺通气,单肺通气开始后,其中容量控制通气模式(VCV)组(Ⅰ组)VT=10 ml/kg,f=10;压力控制通气模式(PCV)(Ⅱ组)压力设定为达10 ml/kg潮气量的压力值,f=10;VCV组(Ⅲ组)VT=7 ml/kg,f=14;PCV组(Ⅳ组)压力设定为达7 ml/kg潮气量的压力值,f=14;VCV+选择性通气肺呼气末正压组(PEEP)(Ⅴ组)VT=7 ml/kg,f=14,PEEP=5 cm H2O;PCV+PEEP组(Ⅵ组)压力设定为达7 ml/kg潮气量的压力值,f=14,PEEP=5 cm H2O。定时记录数据。结果单肺通气30 min后、单肺通气60 min后,Ⅲ组和Ⅳ组相比氧合具有显著统计学差异(P<0.05),Ⅲ组和Ⅴ组相比氧合具有显著统计学差异(P<0.05),Ⅳ组和Ⅵ组相比氧合具有显著统计学差异(P<0.05)。结论为了改善单肺通气时出现的低氧血症和确保患者在手术中的安全,需要合理选择通气模式,达到提高单肺通气效果的目的,使单肺通气技术得到广泛的推广。     

A comparative study of the cardiorespiratory effects of continuous positive airway pressure breathing and continuous positive pressure ventilation in acute respiratory failure

Positive end expiratory pressure (PEEP) produces cardiopulmonary effects whether administered by controlled positive pressure ventilation (CPPV) or continuous positive airway pressure (CPAP). In eight patients with acute respiratory failure, the effects of 20 cm PEEP administered via CPPV and CPAP were compared. An esophageal balloon was used to calculate the transmural vascular pressures. The control values under mechanical ventilation with no PEEP (IPPV) for PaO₂ and QS/QT (FiO₂ being 1.0) were respectively 132±15 mmHg and 31±3%; CPPV gave a PaO₂ of 369±27 mmHg and QS/QT fo 14±1.6%, CPAP 365±18 mmHg and 18±1.3% respectively. The two different modes of ventilation (CPPV and CPAP) gave identical blood gas improvement through the same level of end expiratory transpulmonary pressure despite marked differences between absolute mean airway and esophageal pressures. Conversely, hemodynamic tolerance was very different from one technique to the other: CPPV depressed cardiac index from 3.4±0.3 to 2.4±0.2 l/min/m² as well as decreasing transmural filling pressures, suggesting a reduction in venous return. Conversely, filling pressures maintained at control values during CPAP and cardiac indexes were unchanged.Abbreviations IPPV intermittent positive pressure ventilation; mechanical ventilation (controlled mode) with zero end expiratory pressure (ZEEP) - CPPV continuous positive pressure ventilation: mechanical ventilation (controlled mode) with a positive pressure during expiration - CPAP continuous positive airway pressure; spontaneous ventilation with a positive pressure maintained during expiration - PEEP positive end expiratory pressure, whatever the ventilatory mode; spontaneous (CPAP) or mechanical (CPPV) Presented in part at the 44 th annual meeting of American College of Chest Physicians, Washington DC, October 1978     

Noninvasive positive pressure ventilation in infants with upper airway obstruction: comparison of continuous and bilevel positive pressure

Objective This study evaluated the efficacy of noninvasive continuous positive pressure (CPAP) ventilation in infants with severe upper airway obstruction and compared CPAP to bilevel positive airway pressure (BIPAP) ventilation.Design and setting Prospective, randomized, controlled study in the pulmonary pediatric department of a university hospital.Patients Ten infants (median age 9.5 months, range 3—18) with laryngomalacia (n=5), tracheomalacia (n=3), tracheal hypoplasia (n=1), and Pierre Robin syndrome (n=1)Interventions Breathing pattern and respiratory effort were measured by esophageal and transdiaphragmatic pressure monitoring during spontaneous breathing, with or without CPAP and BIPAP ventilation.Measurements and results Median respiratory rate decreased from 45 breaths/min (range 24–84) during spontaneous breathing to 29 (range 18–60) during CPAP ventilation. All indices of respiratory effort decreased significantly during CPAP ventilation compared to unassisted spontaneous breathing (median, range): esophageal pressure swing from 28 to 10 cmH₂O (13–76 to 7–28), esophageal pressure time product from 695 to 143 cmH₂O/s per minute (264–1417 to 98–469), diaphragmatic pressure time product from 845 to 195 cmH₂O/s per minute (264–1417 to 159–1183) During BIPAP ventilation a similar decrease in respiratory effort was observed but with patient-ventilator asynchrony in all patients.Conclusions This short-term study shows that noninvasive CPAP and BIPAP ventilation are associated with a significant and comparable decrease in respiratory effort in infants with upper airway obstruction. However, BIPAP ventilation was associated with patient-ventilator asynchrony.     

Continuous passive oxygen insufflation results in a similar outcome to positive pressure ventilation in a swine model of out-of-hospital ventricular fibrillation

BACKGROUND: The deleterious effects of positive pressure ventilation may be prevented by substituting passive oxygen insufflation during advanced cardiac life support (ACLS) cardiopulmonary resuscitation (CPR). METHODS: We compared 24-h neurologically normal survival among three different ventilation scenarios for ACLS in a realistic swine model of out-of-hospital prolonged ventricular fibrillation (VF) cardiac arrest. No bystander CPR was provided during the first 8 min of untreated VF before the simulated arrival of an emergency medical system (EMS). Thirty-six swine were randomly assigned to one of three experimental groups. Group I (standard ventilation) was mechanically ventilated at 10 respirations per minute (RPM) at a tidal volume (TV) of 10 ml/kg with 100% oxygen. Group II (hyperventilation) was ventilated at 35 RPM at a TV of 20 ml/kg with 100% oxygen. In Group III (insufflation) animals, a nasal cannula was placed in the oropharynx to administer oxygen continuously at 10 l/min. RESULTS: There was no significant difference in the 24h neurologically normal survival among groups (standard: 2/12, hyperventilation: 2/12, insufflation: 4/12; p=.53). CONCLUSIONS: Passive insufflation may be an acceptable alternative to the currently recommended positive pressure ventilation during resuscitation efforts for out-of-hospital VF cardiac arrest. Potential advantages of this technique include: (1) easier to teach, (2) easier to administer, (3) prevention of the adverse effects of positive pressure ventilation and (4) allows EMS personnel to concentrate upon other critically important duties.     

Comparison of ventilation and chest compression performance by bystanders using the Impact Model 730 ventilator and a conventional bag valve with mask in a model of adult cardiopulmonary arrest

"Bystanders" or lay persons are typically the first caregivers to attend to a victim of out-of-hospital cardiopulmonary arrest. Astronaut crew medical officers (CMO) play a similar role to bystanders aboard the International Space Station (ISS). Studies have demonstrated the importance of bystander cardiopulmonary resuscitation (BCPR) for patient survival before the arrival of emergency medical care. Recent apprehension from bystanders about the threat of contracting communicable diseases during BCPR, however, has led to the consideration of other ventilation systems such as the bag-valve mask (BVM) and automatic transport ventilators (ATV). BVM use is called for during CPR aboard the ISS. This study evaluated the ventilation and compression performance of 40 basic CPR-trained bystanders using either a BVM (adult-sized self-inflating bag with face mask) or an ATV (Model 730 ventilator (M730), Impact Instrumentation, Inc., West Caldwell, NJ). Each two-bystander team gave BCPR to a simulated cardiopulmonary arrest victim using the 2-breath/15-compression cycle for 4 min and then switched roles for another 4-min interval. Compared to BVM use, the M730 led to significantly (p<0.05) lower number of breaths, smaller tidal volumes, airway flows, airway pressures, volume of gas entering the stomach per breath and chest compressions for the 4-min period. The M730 also enabled a bystander to meet the recommendation of 4-breath and compression cycles per minute as per Guidelines 2000. Lastly, ease-of-use scores were significantly higher for the M730 compared to the BVM. Overall, the data suggest that the M730 improves the quality of performance for a bystander performing BCPR.     

呼气末二氧化碳分压监测在呼吸衰竭患者监护中的应用

目的 探讨呼气末二氧化碳分压(PetCO_2)和动脉血二氧化碳分压(PaCO_2)的相关性及其在呼吸衰竭患者监护中的临床应用意义和护理体会.方法 将112例入住ICU进行PetCO_2监测的患者按血流动力学情况分为2组,血流动力学较稳定的患者58例作为A组,血流动力学不稳定的患者54例作为B组.2组均接受气管插管呼吸机辅助通气,在通气支持2h后同时测定PetCO_2和PaCO_2并对结果进行分析.结果 A组患者的PetCO_2和PaCO_2显著相关,B组患者的PetCO_2和PaCO_2无显著相关.结论 对于血流动力学稳定的患者,PetCO_2和PaCO_2具有良好的相关性,可由PetCO_2来代替PaCO_2的监测,PetCO_2能迅速敏感地反映PaCO_2的变化,具有无创、连续、动态、简便、节约之优点.     

Basic life support with four different compression/ventilation ratios in a pig model: The need for ventilation

Background

During cardiac arrest the paramount goal of basic life support (BLS) is the oxygenation of vital organs. Current recommendations are to combine chest compressions with ventilation in a fixed ratio of 30:2; however the optimum compression/ventilation ratio is still debatable. In our study we compared four different compression/ventilation ratios and documented their effects on the return of spontaneous circulation (ROSC), gas exchange, cerebral tissue oxygenation and haemodynamics in a pig model.

Methods

Study was performed on 32 pigs under general anaesthesia with endotracheal intubation. Arterial and central venous lines were inserted. For continuous cerebral tissue oxygenation a Licox^® PtiO₂ probe was implanted. After 3 min of cardiac arrest (ventricular fibrillation) animals were randomized to a compression/ventilation-ratio 30:2, 100:5, 100:2 or compressions-only. Subsequently 10 min BLS, Advanced Life Support (ALS) was performed (100%O₂, 3 defibrillations, 1 mg adrenaline i.v.). Data were analyzed with 2-factorial ANOVA.

Results

ROSC was achieved in 4/8 (30:2), 5/8 (100:5), 2/8 (100:2) and 0/8 (compr-only) pigs. During BLS, PaCO₂ increased to 55 mmHg (30:2), 68 mmHg (100:5; p = 0.0001), 66 mmHg (100:2; p = 0.002) and 72 mmHg (compr-only; p < 0.0001). PaO₂ decreased to 58 mmg (30:2), 40 mmHg (100:5; p = 0.15), 43 mmHg (100:2; p = 0.04) and 26 mmHg (compr-only; p < 0.0001). PtiO₂ baseline values were 12.7, 12.0, 11.1 and 10.0 mmHg and decreased to 8.1 mmHg (30:2), 4.1 mmHg (100:5; p = 0.08), 4.3 mmHg (100:2; p = 0.04), and 4.5 mmHg (compr-only; p = 0.69).

Conclusions

During BLS, a compression/ventilation-ratio of 100:5 seems to be equivalent to 30:2, while ratios of 100:2 or compressions-only detoriate peripheral arterial oxygenation and reduce the chance for ROSC.     

A comparison of the imposed work of breathing in continuous positive pressure ventilation mode between three different ventilators

Abstract Objective: To compare the work of breathing imposed and patient tolerance to the delivery of face mask continuous positive pressure ventilation by three different ventilators. Methods: Eleven healthy volunteers were subject to continuous positive pressure ventilation at levels of 0, 5, 10 and 15 cmH₂O on each of the three machines tested (Oxylog 2000, Drägerwerk AG, Lubeck, Germany; Puritan-Bennett 7200, Puritan Bennett Corp., Carlsbad, CA, USA; Auspap, Ulco Engineering Pty Ltd, Marrickville, NSW, Australia). The work of breathing imposed by the machines was measured using the Bicore-CP100 pulmonary function monitor (Allied Healthcare Products, CA, USA). After breathing on the three machines, volunteers rated the comfort of breathing on a visual analogue scale. Results: The work of breathing imposed by the Oxylog 2000 was higher in all volunteers receiving face mask continuous positive pressure ventilation when compared with both the Puritan-Bennett 7200 and the Auspap. The Oxylog 2000 was considered to be the least comfortable. Conclusions: The provision of continuous positive pressure ventilation in the emergency department is becoming increasingly common, but the use of a transport ventilator, such as the Oxylog 2000, to provide this ventilatory support cannot currently be recommended.     

Need for oxygen therapy and ventilatory support in premature infants in a hospital in Southern Brazil

BACKGROUNDPrematurity in newborns is a condition that is associated with worse hospital outcomes when compared to birth to term. A preterm infant (PI) is classified when gestational age (GA) < 37 wk.AIMTo analyze prognostic indicators related to the use of oxygen therapy, non-invasive ventilation (continuous positive airway pressure) and mechanical ventilation (MV) in PI. METHODSThis is a retrospective cohort. The sample was composed of PIs from a private hospital in southern Brazil. We included neonates with GA < 37 wk of gestation in the period of January 1, 2018 to December 31, 2018. For data collection, electronic records were used in the Tasy Philips^TM system, identifying the variables: maternal age, type of birth, prenatal information, GA, Apgar score, birth weight, neonatal morbidities, vital signs in the 1st hour at birth, need for oxygen therapy, continuous positive airway pressure and MV, hospitalization in the neonatal intensive care unit, length of stay and discharge or death.RESULTSIn total, 90 PI records were analyzed. The median (p25-p75) of GA was 34.0 (31.9-35.4) wk, and there were 45 (50%) males. The most common morbidity among PIs was the acute respiratory discomfort syndrome, requiring hospitalization in the neonatal intensive care unit in 76 (84.4%) cases. The utilization rate of oxygen therapy, continuous positive airway pressure and MV was 12 (13.3%), 37 (41.1%) and 13 (14.4%), respectively. The median (p25-p75) length of stay was 12.0 (5.0-22.2) d, with 10 (11.1%) deaths. A statistical association was observed with the use of MV and GA < 28 wk, lower maternal age, low birth weight, Apgar < 8 and neonatal deaths.CONCLUSIONThe identification of factors related to the need for MV in prematurity may help in the indication of a qualified team and technologies to promptly meet the unforeseen events that may occur after birth.     

A simple automatic record of oxygenation and ventilation with a pulse oximeter and a carbon dioxide monitor

Many cases have come to medicolegal attention in which a healthy patient undergoing a routine, elective operation has had an unexpected cardiac arrest attributed to hypoxia or hypercarbia. A simple, objective, automatic, inexpensive record of the adequacy of oxygenation and ventilation was obtained by using the Nellcor N-100 pulse oximeter, the Puritan-Bennett/Datex carbon dioxide monitor, and the Nellcor N-9000 recorder in combination. The required interface is described, and a sample record is presented. A second interface allows the recorder to work with the Puritan-Bennett anesthesia and brain activity monitor (ABM-1). Oxygen saturation can also be displayed on the video screen of the anesthesia and brain activity monitor.     

压力控制通气与高频喷射通气在小儿气道异物取出术中通气效果的比较

目的：比较压力控制机械通气与高频喷射通气在小儿气道异物取出术中的通气效果。方法：拟行气道异物取出术患儿60例,年龄8月～3岁,体重7～15kg,ASAI-Ⅱ级。随机分为2组：P组通过硬支气管镜侧孔行压力控制机械通气;H组高频喷射通气。对患儿术前、术后即刻进行血气分析,记录术前SpO2、术中缺氧情况、手术时间、麻醉苏醒时间、术中不良事件发生情况。结果：P组和H组在术前即刻血气结果（PaO2,PaCO2,SaO2）及SpO2无显著性差异,但在术后即刻H组PaO2高于P组（P〈0．05）,且PaCO2较P组低（P〈0．05）。P组与H组术中缺氧的发生率,手术时间及麻醉苏醒时间均无显著性差异。结论：压力控制机械通气与高频喷射通气在小儿异物取出术中的通气效果相当,压力控制机械通气在小儿异物取出术中可得以广泛应用。     

Characteristics and risk factors of facial pressure injuries in acute inpatients using noninvasive positive pressure ventilation: A retrospective case control study

ObjectiveTo explore the characteristics and risk factors of facial pressure injuries in patients using noninvasive positive pressure ventilation.Setting and samplePatients who developed facial pressure injuries due to non-invasive positive pressure ventilation at a teaching hospital in Taiwan from January 2016 to December 2021 were selected, resulting in a total of 108 patients in our case group. A control group was formed by matching each case by age and gender to three acute inpatients who had used non-invasive ventilation but had not developed facial pressure injuries, resulting in 324 patients in the control group.Research methodologyThis study was a retrospective case-control study. The characteristics of the patients who developed pressure injuries at different stages in the case group were compared, and the risk factors of non-invasive ventilation-related facial pressure injuries were then determined.ResultsHigher duration of non-invasive ventilation usage, higher length of hospital stay, lower Braden scale score, and lower albumin levels in the former group. The results of multivariate analysis from binary logistic regression involving the duration of non-invasive ventilation usage demonstrated that the patients who used this device for 4–9 days and 16 days were at greater risk of facial pressure injuries than those who used it for 3 days; in terms of the Braden scale score, higher Braden scale scores were correlated with a higher risk of facial pressure injuries. In addition, albumin levels lower than the normal range were correlated with a higher risk of facial pressure injuries.ConclusionPatients with pressure injuries at higher stages had a higher duration of non-invasive ventilation usage, higher length of hospital stay, lower Braden scale scores, and lower albumin levels. Thus, a longer duration of non-invasive ventilation use, lower Braden scale scores, and lower albumin levels were also risk factors for non-invasive ventilation-related facial pressure injuries.Implications for clinical practiceOur results serve as a useful reference for hospitals, both in creating training programs for their medical teams to prevent and treat facial pressure injuries and in drafting guidelines for assessing risk in order to prevent facial pressure injuries caused by non-invasive ventilation. The duration of device usage, Braden scale scores, and albumin levels in particular should be seriously monitored to reduce the occurrence of facial pressure injuries in acute inpatients treated with non-invasive ventilation.     

无创正压通气对急性呼吸衰竭患者拔管后再插管率和预后影响的荟萃分析

目的 探讨无创正压通气对急性呼吸衰竭患者拔管后再插管率和预后的影响.方法 通过计算机检索和手工检索中文期刊数据库,Pubmed,Embase,Web of Science数据库,收集1995年1月1日至2010年6月30日关于无创正压通气对急性呼吸衰竭患者拔管后进行呼吸支持和治疗的随机对照研究,按Cochrane协作网推荐的方法对拔管后采用无创正压通气进行呼吸辅助治疗患者的再插管率和病死率行Meta评价.结果 共纳入6篇随机对照研究,其中拔管后无创正压通气组(治疗组)患者381例,拔管后常规氧疗组(对照组)患者379例,治疗组和对照组患者的病死率分别为18.6%(62/334)vs.21.6%(72/333)(P=0.34),再插管率分别为30.2%(115/381)vs.33.5%(127/379)(P=0.27).与常规氧疗相比,拔管后无创正压通气不能降低患者再插管率,也不能改善患者预后.对拔管后即开始进行无创正压通气的患者进行分析,结果提示治疗组患者病死率明显降低[12.2%(22/181)vs.23.9%(44/184),P=0.004],再插管率减少;但与对照组相比,差异无统计学意义[14.0%(32/228)vs.20.4%(47/230),P=0.07].结论 急性呼吸衰竭患者拔管后早期行无创正压通气有助于减少患者再插管率,可显著改善患者预后.

Abstract：

Objective To evaluate the effects of noninvasive positive pressure ventilation (NPPV)used after extubation on mortality and rate of reintubation in patients with acute respiratory failure (ARF).Method Pubmed, Embase, Web of Science databases were searched to collect data from randomized controlled trials (RCT) of the relevant subject from January 1995 to May 2010. Meta analysis of data about NPPV on mortality and rate of reintubation in patients after extubation carried out by using the methods recommended by the Cochrane Collaboration. Results Six RCTs included sample size of 381 NPPV and 379routine medical care. In total, the mortalities of patients in NPPV group and routine medical care group were 18.6% (62/334) vs. 21.6% (72/333), respectively, and the rates of reintubation of the two groups were 30.2% (115/381) vs. 33.5% (127/379), respectively. Compared with routine medical care, NPPV did not significantly reduce the mortality ( OR: 0.83, 95% CI =0.57 ～ 1.21 ,P =0.34) and rate of reintuation( OR: 0.83, 95% CI = 0.59 ～ 1.16, ( P = 0.27). When the analysis was focused to the four studies of them in which patients received NPPV as soon as extubation, the results were quite different. From these four studies, the mortalities of patients in NPPV group and routine medical care group were 12. 2% (22/181) vs.23.9% (44/184),(P=0.004), and the rate of reintubation of the two groups were 14.0% (32/228) vs.20.4% (47/230), (P =0.07). Compared with routine medical care, early application of NPPV to patients after extubation reduced the mortality. Conclusions This study suggests the favorable effects of early application of NPPV to patients after extubation on the mortality of acute respiratory failure.     

Risk factors for the deterioration of oxygenation ratio in ventilated intensive care unit patients: A retrospective cohort study

Purpose

The aim of the study is to determine which factors are associated with the deterioration of Pao₂/fraction of inspired oxygen (Fio₂) ratio in patients with normal oxygenation at admission and ventilated according to a lung protective ventilation strategy.

Materials and Methods

Retrospective cohort study of ventilated (≥3 days) intensive care unit patients with an admission Pao₂/Fio₂ ratio of 300 mm Hg or higher (n = 105). Patients who developed lung injury (Pao₂/Fio₂ ratio, <300 mm Hg) on day 7 (n = 37) were compared to those who did not (n = 68), with regard to ventilator settings, gas exchange variables, and lung injury risk factors.

Results

Mean ± SD of administered tidal volume was 7.9 ± 1.3 mL/kg. Patients who developed lung injury were older (P = .019), had lower Pao₂ (P = .009), higher Paco₂ (P = .045), and lower Pao₂/Fio₂ ratio (P = .002) at admission. Postoperative state (Hazard risk [HR], 5.1) and controlled ventilation mode (HR, 4.3) were identified as independent risk factors. Lung injury-free time was shorter in patients with low initial Pao₂/Fio₂ ratio (odds ratio, 1.7; P = .039). This effect was not only caused by the baseline difference, as the decrease in Pao₂/Fio₂ ratio was more pronounced in patients who developed lung injury compared to those who did not (P = .008).

Conclusions

Lung injury exacerbates during mechanical ventilation. In patients treated with a mean tidal volume of 7.9 mL/kg, controlled ventilation is a major risk factor.     

气道压力释放通气对急性呼吸窘迫综合征患者疗效的Meta分析

目的系统评价气道压力释放通气（APRV）治疗急性呼吸窘迫综合征（ARDS）患者的疗效。 方法计算机检索Cochrane Library、PubMed、Embase、中国生物医学文献数据库、中国知网、万方数据库,查找关于APRV与常规机械通气对比治疗ARDS患者的随机对照试验（RCTs）,检索时限从建库到2021年3月。由2名研究者按照纳入与排除标准筛选文献、提取数据和评价质量后,采用RevMan 5.2软件和Stata 1.4软件进行Meta分析。 结果共纳入11项RCTs,合计611例患者。Meta结果显示,治疗后,APRV组ARDS患者的氧合指数高于对照组[均数差（MD）= 31.70,95%置信区间（CI）（3.76,59.63）,Z = 2.22,P = 0.03],且APRV组患者28 d病死率显著低于对照组[比值比（OR）= 0.55,95%CI（0.36,0.84）,Z = 2.77,P = 0.006]。 结论对于ARDS患者而言,早期应用APRV能够增加氧合功能,降低28 d病死率。     

Extended series of cardiac compressions during CPR in a swine model of perinatal asphyxia

Background

The rationale for a compression to ventilation ratio of 3:1 in neonates with primary hypoxic, hypercapnic cardiac arrest is to emphasize the importance of ventilation; however, there are no published studies testing this approach against alternative methods. An extended series of cardiac compressions offers the theoretical advantage of improving coronary perfusion pressures and hence, we aimed to explore the impact of compression cycles of two different durations.

Materials and methods

Newborn swine (n = 32, age 12-36 h, weight 2.0-2.7 kg) were progressively asphyxiated until asystole occurred. Animals were randomized to receive compressions:ventilations 3:1 (n = 16) or 9:3 (n = 16). Return of spontaneous circulation (ROSC) was defined as a heart rate ≥100 beats min⁻¹.

Results

All animals except one in the 9:3 group achieved ROSC. One animal in the 3:1 group suffered bradycardia at baseline, and was excluded, leaving us with 15 animals in each group surviving to completion of protocol. Time to ROSC (median and interquartile range) was 150 s (115-180) vs. 148 s (116-195) for 3:1 and 9:3, respectively (P = 0.74). There were no differences in diastolic blood pressure during compression cycles or in markers of hypoxia and inflammation. The temporal changes in mean arterial blood pressure, heart rate, arterial blood gas parameters, and systemic and regional oxygen saturation were comparable between groups.

Conclusion

Neonatal pigs with asphyxia-induced cardiac arrest did not respond to a compression:ventilation ratio of 9:3 better than to 3:1. Future research should address if alternative compression:ventilation ratios offer advantages over the current gold standard of 3:1.