Nursing evaluation during treatment with helmet continuous positive airway pressure in patients with respiratory failure due to COVID-19 pneumonia: A case series

BackgroundDuring COVID-19 outbreak, with the increasing number of patients presenting with acute respiratory failure, a large use of non invasive positive pressure ventilation was done in the emergency departments and medical wards despite the lack of recommendations.ObjectivesThis study describes the clinical characteristics of patients presenting to the hospital with acute respiratory failure due to COVID-19 related pneumonia undergoing treatment with helmet continuous positive airway pressure (CPAP) with a strict nursing evaluation and monitoring.MethodsA case series study enrolling adult patients admitted to an emergency department of an Italian hospital with acute respiratory failure due to COVID-19 pneumonia from March 18th to April 18th, 2020, was conducted. Only patients who strictly followed a local CPAP protocol were enrolled.ResultsA total of 52 patients were included in this study. Thirty-eight patients (73%) were judged eligible for endotracheal intubation (ETI). Eighteen (34.6%) were intubated. Sixteen (30.8%) patients died: seven (38.9%) and nine (26.5%) in the eligible-for-ETI and non eligible-for-ETI group, respectively. The median hospital length of stay was different in the ETI and non-ETI group: 26 days (interquartile range [IQR]: 16–37) vs 15 days [IQR 9–17] (p = 0.005). The median invasive mechanical ventilation time was 11 days [IQR 7–21] with an ICU length of stay of 14.5 days [IQR 10–28]. During the CPAP trial, among patients eligible for ETI variations over time for positive end-expiratory pressure (p = 0.003) and respiratory rate (p = 0.059) were found between intubated and non-intubated patients.ConclusionsA short closed monitored CPAP trial could be considered for acute respiratory failure due to COVID-19 pneumonia before considering ETI. A progressive positive end-expiratory pressure titration should target reduction in a patient’s respiratory rate. More studies are needed to evaluate the efficacy and predictors of failure of CPAP and non-invasive positive pressure ventilation in patients with acute respiratory failure due to COVID-19 pneumonia.     

经面罩持续气道正压治疗急性肺损伤致呼吸衰竭的临床研究

目的 评价经面罩持续气道正压通气（CPAP）治疗急性肺损伤致呼吸衰竭的疗效。方法 67例患者被随机分为CPAP治疗组和对照组，比较2组治疗1、24h后的动脉血气值，呼吸频率和脉率及1h后的主观效果。结果 1h时CPAP治疗组较对照组明显改善动脉血氧合，降低呼吸频率和脉率，改善临床症状。24h后两组结果无明显差异。结论 CPAP应用于急性肺损伤所致呼吸衰竭时，虽可改善早期生理状况，但不能改善患者预后。     

Noninvasive continuous positive airway pressure ventilation using a new helmet interface: a case-control prospective pilot study

Objective To evaluate the clinical efficacy of noninvasive continuous positive airway pressure ventilation (CPAP) using a new interface, constituted by a cephalic plastic helmet, in comparison with a standard facial mask.Design and setting A prospective pilot study with matched-control group, in the emergency department of a teaching hospitalPatients and methods Eleven consecutive adult patients with acute hypoxemic respiratory failure related to cardiogenic pulmonary edema (whether hypercapnic or not) were enrolled in the study, after failure of the initial medical treatment. Each patient treated with CPAP, using the helmet in addition to a standardized medical treatment, was matched with historical control-patient treated with CPAP using a standard facial mask, and selected by gender, age, and PaCO₂ levels on admission. Primary end points were improvements of gas exchanges and clinical parameters of respiratory distress. Tolerance was evaluated after each CPAP trial.Results The 22 patients and controls had similar characteristics at baseline. PaCO₂ levels, and clinical parameters improved similarly in both groups. No interface intolerance was reported whether using standard facial mask or the helmet. No complications were observed in either group. The helmet allowed CPAP administration for a longer period of time (p=0.045). In-hospital mortality was not different between the two groups.Conclusion Despite a high dead-space volume (9–15 l), this new helmet interface is an efficient alternative to standard face mask during CPAP, even in cases of severe respiratory acidosis and hypercapnia. It allows to provide long-duration CPAP, without any adverse events or clinical intolerance.     

食管引流型与标准型喉罩通气道用于正压通气的自身对照研究

目的采用随机自身对照设计方法比较食管引流型喉罩通气道(PLMA)和标准型喉罩通气道(SLMA)用于间歇正压通气的有效性。方法选择50例经美国麻醉医师协会(ASA)身体状态分级标准分为1~2级、拟在全身麻醉下实施择期整形外科手术患者。在常规麻醉诱导后,顺序插入PLMA和SLMA,将通气罩内压充气至60cmH2O(1cm H2O=0.098kPa),评价两种喉罩通气道充气前后的肺通气满意度和气道密封压,同时进行光导纤维支气管镜(FOB)评分,确定通气罩的解剖位置。然后将潮气量设定为10ml/kg实施间歇正压通气,记录间歇正压通气后连续5次呼吸的平均呼潮气量和平均吸气峰压。结果在通气罩未充气情况下,插入PLMA后有46例(92%)患者获得了良好和尚可的肺通气效果,而插入SLMA后仅有22例(44%)患者获得了良好和尚可的肺通气效果;PLMA的气道密封压显著高于SLMA(P<0.05)。将通气罩内压充气至60cmH2O,采用PLMA的50例患者均获得良好的肺通气效果,但采用SLMA时仅有28例获得良好的肺通气效果;PLMA所需的充气量和充气后获得的气道密封压均显著高于SLMA(P均<0.05)。采用PLMA时所有患者的气道密封压均高于或等于采用SLMA时;采用PLMA时除2例患者外,其他患者所需的充气量也均高于采用SLMA时。PLMA通气罩位置的FOB评分显著低于SLMA(P<0.05)。采用PLMA维持气道的29例患者和采用SLMA维持气道的21例患者的平均呼潮气量、吸气峰压及维持气道时间差异均无显著性(P均>0.05)。结论与SLMA相比,PLMA可为正压通气提供更好的气道密封压,而且对声门和食管上端具有潜在的隔离作用,用于正压通气时PLMA比SLMA更有效、更安全。     

Danger of helmet continuous positive airway pressure during failure of fresh gas source supply

Objective To assess the behavior of different helmets after discontinuation of fresh gas flow by disconnection at the helmet inlet, flow generator, or gas source. Design and setting Randomized physiological study in a university research laboratory. Patients Five healthy volunteers. Intervention CPAP (FIO₂ 50%, PEEP 5 cmH₂O) delivered in random sequence with three different helmets: 4Vent (Rüsch), PN500 (Harol), CaStar (StarMed) with antisuffocation valve open or locked. For each helmet all three disconnections were randomly employed up to 4 min. Measurements and results During flow disconnection we measured: respiratory rate and tidal volume by respitrace; inspiratory and expiratory CO₂ concentration, and FIO₂ from a nostril; SpO₂ by pulse oxymetry. Independently of the site of disconnection we observed a fast increase in CO₂ rebreathing and minute ventilation, associated with a decrease in inspired O₂ concentration. In the absence of an operational safety valve, larger helmet size and lower resistance of the inlet hose resulted in slower increase in CO₂ rebreathing. The presence of the safety valve limited the rebreathing of CO₂, and the increase in minute ventilation but did not protect from a decrease in FIO₂ and loss of PEEP. Conclusions While the use of a safety valve proved effective in limiting CO₂ rebreathing, it did not protect from the risk of hypoxia related to decrease in FIO₂ and loss of PEEP. In addition to a safety antisuffocation valve, a dedicated monitoring and alarming systems are needed to employ helmet CPAP safely.     

Optimum versus clinically established levels of continuous positive airway pressure in respiratory therapy

To evaluate the efficacy of our routine method of cardiopulmonary monitoring for accurate management of respiratory therapy, continuous positive airway pressure (CPAP) was titrated in 11 surgical intensive care patients within ±7.5 cm H₂O of the clinically selected level. Cardiopulmonary data were independently and retrospectively reviewed by three experienced critical care physicians from three outside hospitals. Each physician estimated the optimum level of CPAP for each patient. Variability between reviewers was not statistically significant. The optimum CPAP level based on all reviewers' opinions (8.6±5.7 cm H₂O, mean±SD) was significantly lower than that selected clinically (13.2±4.5 cm H₂O;P<0.05). We conclude that current methodology for monitoring respiratory therapy is inefficient for rapid adjustment of CPAP to appropriate levels. Continuous arterial and pulmonary artery oximetry may provide an improvement in the efficacy of cardiopulmonary monitoring in the future.     

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     

A new device for administration of continuous positive airway pressure in preterm infants: comparison with a standard nasal CPAP continuous positive airway pressure system

Objective We compared the effectiveness of a new continuous positive airway pressure (CPAP) device (neonatal helmet CPAP) with a conventional nasal CPAP system in preterm neonates needing continuous distending pressure.Design and setting Randomized, physiological, cross-over study in a tertiary referral, neonatal intensive care unit in a university teaching hospital.Patients Twenty very low birth weight infants with a postnatal age greater than 24 h who were receiving nasal CPAP for apnea and/or mild respiratory distress were enrolled.Interventions CPAP delivered by neonatal helmet CPAP and nasal CPAP in random order for two subsequent 90-min periods.Measurements and results Were continuously measured the Neonatal Infant Pain Scale (NIPS) score, oxygen requirements, respiratory rate, heart rate, oxygen saturation, transcutaneous PO₂ (tcPO₂) and PCO₂ (tcPCO₂), blood pressure, and desaturations. NIPS scores were significantly lower when the infants were on the neonatal helmet CPAP than when they were on nasal CPAP (0.26±0.07 vs. 0.63±0.12). The other studied parameters did not differ between the two CPAP modes. The number of deaturations was reduced during the neonatal helmet CPAP treatment (18 vs. 32), although this difference was not significant.Conclusions In this short-term physiological study the neonatal helmet CPAP appears to be as good as the golden standard for managing preterm infants needing continuous distending pressure, with enhanced tolerability. Further evaluation in a randomized clinical trial is needed to confirm these findings.     

气道压力释放通气和持续气道正压开放肺的比较

目的探讨气道压力释放通气（APRV）与持续气道正压（CPAP）通气两种通气模式实施肺复张策略治疗急性呼吸窘迫综合征（ARDS）对血流动力学、肺力学和氧代谢指标的影响。方法选择ARDS行机械通气及脉搏轮廓法持续血流动力学监测的患者15例，随机实施APRV模式肺复张或CPAP模式肺复张，每隔4h复张1次。其中APRV组设定高水平压力（Phigh）为35cm H2O（1cm H2O=0．098kPa），低水平压力（Plow）为压力-容积（P—V）曲线的下拐点（LIP）；CPAP组设定CPAP为35cm H2O；两组持续时间均为40s。记录复张前后的肺力学、氧代谢指标以及复张时的血流动力学变化。结果在APRV模式下行肺复张时心脏指数（CI）轻度下降，且持续时间较短。两种复张模式均可使肺顺应性等力学参数及氧合明显改善，以APRV模式尤为明显。结论采用APRV模式进行ARDS肺复张治疗可避免镇静剂的使用，对血流动力学干扰较小，对肺力学及氧合的改善优于CPAP模式。     

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.