Clinical concise review: Mechanical ventilation of patients with chronic obstructive pulmonary disease:

[Measurement of intrinsic positive end-expiratory pressure and clinical outcomes of infants with severe bronchopulmonary dysplasia]

OBJECTIVES

To investigate the levels of intrinsic positive end-expiratory pressure (PEEPi) in infants with severe bronchopulmonary dysplasia (sBPD) and the relationship between different levels of PEEPi and clinical outcomes.

METHODS

A retrospective analysis was conducted on the clinical data of 12 sBPD infants who underwent PEEPi measurement and were hospitalized at Guangzhou Women and Children's Medical Center from January 2022 to June 2023. The clinical manifestations and outcomes at discharge were compared between infants with very high PEEPi (≥10 cmH2O) and those with lower PEEPi (<10 cmH2O).

RESULTS

PEEPi measurements were taken in 12 sBPD infants between gestational age 31+3 and 67+2 weeks postmenstrual age, with the lowest PEEPi measured at 0.9 cmH2O and the highest at 19.6 cmH2O; 50% (6/12) of the infants had PEEPi ≥10 cmH2O. All infants with very high PEEPi exhibited ineffective triggering and patient-ventilator asynchrony. Among them, 5 infants could not be weaned off invasive ventilation, resulting in 4 deaths and 1 infant being discharged with a tracheostomy and ventilator support. In contrast, among the infants with PEEPi <10 cmH2O, only 1 infant died, while the others were successfully extubated and discharged.

CONCLUSIONS

Infants with sBPD may have elevated PEEPi levels, and very high PEEPi may be associated with adverse outcomes in these patients.

Various Aspects of Non-Invasive Ventilation in COVID-19 Patients: A Narrative Review

Non-invasive ventilation (NIV) is primarily used to treat acute respiratory failure. However, it has broad applications to manage a range of other diseases successfully. The main advantage of NIV lies in its capability to provide the same physiological effects as invasive ventilation while avoiding the placement of an artificial airway and its associated life-threatening complications. The war on the COVID-19 pandemic is far from over. The present narrative review aimed at identifying various aspects of NIV usage, in COVID-19 and other patients, such as the onset time, mode, setting, positioning, sedation, and types of interface. A search for articles published from May 2020 to April 2021 was conducted using MEDLINE, PMC central, Scopus, Web of Science, Cochrane Library, and Embase databases. Of the initially identified 5,450 articles, 73 studies and 24 guidelines on the use of NIV were included. The search was limited to studies involving human cases and English language articles. Despite several reported benefits of NIV, the evidence on the use of NIV in COVID-19 patients does not yet fully support its routine use.

Degree of convexity calculated from expiratory flow-volume curves for identifying airway obstruction in nonsedated and nonparalyzed ventilated patients

The predictive performance of applying the degree of convexity in expiratory flow-volume (EFV) curves to detect airway obstruction in ventilated patients has yet to be investigated. We enrolled 33 nonsedated and nonparalyzed mechanically ventilated patients and found that the degree of convexity had a significant negative correlation with FEV₁% predicted. The mean degree of convexity in EFV curves in the chronic obstructive pulmonary disease (COPD) group (n = 18) was significantly higher than that in the non-COPD group (n = 15; 26.37 % ± 11.94 % vs. 17.24 % ± 10.98 %, p = 0.030) at a tidal volume of 12 mL/kg IBW. A degree of convexity in the EFV curve > 16.75 at a tidal volume of 12 mL/kg IBW effectively differentiated COPD from non-COPD (AUC = 0.700, sensitivity = 77.8 %, specificity = 53.3 %, p = 0.051). The degree of convexity calculated from EFV curves may help physicians to identify ventilated patients with airway obstruction.

Identifying and treating intrinsic PEEP in infants with severe bronchopulmonary dysplasia

RATIONALE

Infants with severe bronchopulmonary dysplasia (sBPD) and airway obstruction may develop dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEP_i ), which impairs patient/ventilator synchrony.

OBJECTIVES

To determine if PEEP_i is present in infants with sBPD during spontaneous breathing and if adjusting ventilator PEEP improves patient/ventilator synchrony and comfort.

METHODS

Interventional study in infants with sBPD. PEEP_i measured by esophageal pressure (Pes) and pneumotachometer, during pressure-supported breaths. PEEP _i defined as the difference between Pes at start of the inspiratory effort minus Pes at onset of inspiratory flow. The set PEEP was adjusted to minimize PEEP _i . "Best PEEP" was the setting with minimal wasted efforts (WE), an inspiratory effort seen on the Pes waveform without a corresponding ventilator breath. FiO ₂ and SpO ₂ measured pre- and post-PEEP adjustment. Sedation requirements evaluated 72 hours preprocedure and postprocedure.

RESULTS

Twelve infants were assessed (gestational age, 24.9 ± 1.4 weeks; study age, 48.8 ± 1.5 weeks, postmenstrual age). Mean baseline ventilator PEEP was 16.4 cm H₂ O (14-20 cm H ₂ O). Eight infants required an increase, one, a reduction, and three, no change in the set PEEP. For the eight infants requiring an increase in set PEEP, there was an 18.9% reduction in WE and a reduction in FiO ₂ (0.084  ±  0.058) requirements in the subsequent 24 hours. Conditional sedation was reduced in five infants postprocedure. No adverse events occurred during testing.

CONCLUSION

PEEP_i is measurable in infants with sBPD with concurrent esophageal manometry and flow-time tracings without the need for pharmacological paralysis. In those with PEEP _i , increasing ventilator PEEP to offset PEEP _i improves synchrony.

The effect of helium-oxygen-assisted mechanical ventilation on chronic obstructive pulmonary disease exacerbation: A systemic review and meta-analysis

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is often accompanied by acute exacerbations. Patients of COPD exacerbation suffering from respiratory failure often need the support of mechanical ventilation. Helium-oxygen can be used to reduce airway resistance during mechanical ventilation. The aim of this study is to evaluate the effect of helium-oxygen-assisted mechanical ventilation on COPD exacerbation through a meta-analysis.

METHODS

A comprehensive literature search through databases of Pub Med (1966∼2016), Ovid MEDLINE (1965∼2016), Cochrane EBM (1991∼2016), EMBASE (1974∼2016) and Ovid MEDLINE was performed to identify associated studies. Randomized clinical trials met our inclusion criteria that focus on helium-oxygen-assisted mechanical ventilation on COPD exacerbation were included. The quality of the papers was evaluated after inclusion and information was extracted for meta-analysis.

RESULTS

Six articles and 392 patients were included in total. Meta-analysis revealed that helium-oxygen-assisted mechanical ventilation reduced Borg dyspnea scale and increased arterial PH compared with air-oxygen. No statistically significant difference was observed between helium-oxygen and air-oxygen as regards to WOB, PaCO2 , OI, tracheal intubation rates and mortality within hospital.

CONCLUSIONS

Our study suggests helium-oxygen-assisted mechanical ventilation can help to reduce Borg dyspnea scale. In terms of the tiny change of PH, its clinical benefit is negligible. There is no conclusive evidence indicating the beneficial effect of helium-oxygen-assisted mechanical ventilation on clinical outcomes or prognosis of COPD exacerbation.

The effect of preexisting respiratory co-morbidities on burn outcomes

INTRODUCTION

Burns cause physiologic changes in multiple organ systems in the body. Burn mortality is usually attributable to pulmonary complications, which can occur in up to 41% of patients admitted to the hospital after burn. Patients with preexisting comorbidities such as chronic lung diseases may be more susceptible. We therefore sought to examine the impact of preexisting respiratory disease on burn outcomes.

METHODS

A retrospective analysis of patients admitted to a regional burn center from 2002-2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, smoker status, length of hospital stay, and days of mechanical ventilation. Bivariate analysis was performed and Cox regression modeling using significant variables was utilized to estimate hazard of progression to mechanical ventilation and mortality.

RESULTS

There were a total of 7640 patients over the study period. Overall survival rate was 96%. 8% (n=672) had a preexisting respiratory disease. Chronic lung disease patients had a higher mortality rate (7%) compared to those without lung disease (4%, p<0.01). The adjusted Cox regression model to estimate the hazard of progression to mechanical ventilation in patients with respiratory disease was 21% higher compared to those without respiratory disease (HR=1.21, 95% CI=1.01-1.44). The hazard of progression to mortality is 56% higher (HR=1.56, 95% CI=1.10-2.19) for patients with pre-existing respiratory disease compared to those without respiratory disease after controlling for patient demographics and injury characteristics.

CONCLUSION

Preexisting chronic respiratory disease significantly increases the hazard of progression to mechanical ventilation and mortality in patients following burn. Given the increasing number of Americans with chronic respiratory diseases, there will likely be a greater number of individuals at risk for worse outcomes following burn.

The feasibility and safety of extracorporeal carbon dioxide removal to avoid intubation in patients with COPD unresponsive to noninvasive ventilation for acute hypercapnic respiratory failure (ECLAIR study): multicentre case-control study

INTRODUCTION

The aim of the study was to evaluate the feasibility and safety of avoiding invasive mechanical ventilation (IMV) by using extracorporeal CO2 removal (ECCO2R) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) and acute hypercapnic respiratory failure refractory to noninvasive ventilation (NIV).

METHODS

Case-control study. Patients with acute hypercapnic respiratory failure refractory to NIV being treated with a pump-driven veno-venous ECCO2R system (iLA-Activve(®); Novalung, Heilbronn, Germany) were prospectively observed in five European intensive care units (ICU). Inclusion criteria were respiratory acidosis (pH ≤ 7.35, PaCO2 > 45 mmHg) with predefined criteria for endotracheal intubation (ClinicalTrials.gov NCT01784367). The historical controls were patients with acute hypercapnic respiratory failure refractory to NIV who were treated with IMV. The matching criteria were main diagnosis, age, SAPS-II score and pH.

RESULTS

Twenty-five cases (48.0 % male, mean age 67.3 years) were matched with 25 controls. Intubation was avoided in 14 patients (56.0 %) in the ECCO2R group with a mean extracorporeal blood flow of 1.3 L/min. Seven patients were intubated because of progressive hypoxaemia and four owing to ventilatory failure despite ECCO2R and NIV. Relevant ECCO2R-associated adverse events were observed in 11 patients (44.0 %), of whom 9 (36.0 %) suffered major bleeding complications. The mean time on IMV, ICU stay and hospital stay in the case and control groups were 8.3 vs. 13.7, 28.9 vs. 24.0 and 36.9 vs. 37.0 days, respectively, and the 90-day mortality rates were 28.0 vs. 28.0 %.

CONCLUSIONS

The use of veno-venous ECCO2R to avoid invasive mechanical ventilation was successful in just over half of the cases. However, relevant ECCO2R-associated complications occurred in over one-third of cases. Despite the shorter period of IMV in the ECCO2R group there were no significant differences in length of stay or in 28- and 90-day mortality rates between the two groups. Larger, randomised studies are warranted for further assessment of the effectiveness of ECCO2R.

Isoflurane rescue therapy for bronchospasm reduces intracranial pressure in a patient with traumatic brain injury

PRIMARY OBJECTIVE

To assess the unusual use of a volatile anaesthetic for treatment of life-threatening bronchospasm in a patient with traumatic brain injury (TBI).

RESEARCH DESIGN

Case report.

METHODS AND PROCEDURES

This study presents a previously healthy 30-year-old man with severe TBI and bronchospasm-induced acute hypercapnia. He was treated with inhaled isoflurane in combination with monitoring of intracranial pressure (ICP) and regional cerebral blood flow (rCBF).

RESULTS

Three-day-long isoflurane treatment resolved drug-refractory bronchospasm, decreased airway pressure and improved gas exchange, even at a low end-tidal concentration (0.3-0.5 vol%). Although rCBF was increased by 18 ml min(-1) 100 g(-1) during isoflurane treatment, there was a significant decrease in ICP (21 (SD = 3) mmHg, 9 (SD = 5) mmHg, 2 (SD = 3) mmHg; during pre-treatment, treatment and post-treatment, respectively; p < 0.001). Improved autoregulation due to lower partial pressure of carbon dioxide, restoration of carbon dioxide reactivity, isoflurane-induced regional differences in rCBF and improved microcirculation may have been responsible for the prompt and long-lasting normalization of ICP. The patient had no TBI-related disability at 6 months post-injury.

CONCLUSIONS

Isoflurane at a low dose can be an effective and safe treatment option for drug-refractory bronchospasm in a patient with traumatic intracranial hypertension, provided that multimodality neuromonitoring is used.

[Hypercapnic respiratory failure. Pathophysiology, indications for mechanical ventilation and management]

BACKGROUND

Acute hypercapnic respiratory failure is mostly seen in patients with chronic obstructive pulmonary disease (COPD) and obesity hypoventilation syndrome (OHS). Depending on the underlying cause it may be associated with hypoxemic respiratory failure and places high demands on mechanical ventilation.

OBJECTIVE

Presentation of the current knowledge on indications and management of mechanical ventilation in patients with hypercapnic respiratory failure.

MATERIAL AND METHODS

Review of the literature.

RESULTS

Important by the selection of mechanical ventilation procedures is recognition of the predominant pathophysiological component. In hypercapnic respiratory failure with a pH < 7.35 non-invasive ventilation (NIV) is primarily indicated unless there are contraindications. In patients with severe respiratory acidosis NIV requires a skilled and experienced team and close monitoring in order to perceive a failure of NIV. In acute exacerbation of COPD ventilator settings need a long expiration and short inspiration time to avoid further hyperinflation and an increase in intrinsic positive end-expiratory pressure (PEEP). Ventilation must be adapted to the pathophysiological situation in patients with OHS or overlap syndrome. If severe respiratory acidosis and hypercapnia cannot be managed by mechanical ventilation therapy alone extracorporeal venous CO2 removal may be necessary. Reports on this approach in awake patients are available.

CONCLUSION

The use of NIV is the predominant treatment in patients with hypercapnic respiratory failure but close monitoring is necessary in order not to miss the indications for intubation and invasive ventilation. Methods of extracorporeal CO2 removal especially in awake patients need further evaluation.

Is hypercapnia associated with poor prognosis in chronic obstructive pulmonary disease? A long-term follow-up cohort study

OBJECTIVES

To assess whether hypercapnia may predict the prognosis in chronic obstructive pulmonary disease (COPD).

DESIGN

Prospective cohort study comparing the survival of patients with COPD and normocapnia to those with chronic hypercapnia.

SETTING

Patients with consecutive COPD were enrolled between 1 May 1993 and 31 October 2006 at two medical centres. Follow-up was censored on 31 October 2011.

PARTICIPANTS

A total of 275 patients with stable COPD and aged 40-85 years were enrolled. Diagnosis of hypercapnia was confirmed by blood gas analysis. Patients with near-terminal illness or comorbidities that affect PaCO2 (obstructive sleep apnoea, obesity-related hypoventilation, or neuromuscular disease) were excluded. The outcome of 98 patients with normocapnia and 177 with chronic hypercapnia was analysed.

OUTCOME MEASURES

Overall survival.

RESULTS

Median survival was longer in patients with normocapnia than in those with hypercapnia (6.5 vs 5.0 years, p=0.016). Multivariate COX regression analysis indicated that age (HR=1.043, 95% CI 1.012 to 1.076), Charlson Index, which is a measure of comorbidity (HR=1.172, 95% CI 1.067 to 1.288), use of medication (HR=0.565, 95% CI 0.379 to 0.842), body mass index (BMI) (HR=0.922, 95% CI 0.883 to 0.963), PaCO2 (HR=1.026, 95% CI 1.011 to 1.042), Cor pulmonale (HR=2.164, 95% CI 1.557 to 3.006), non-invasive positive-pressure ventilation (NPPV) (HR=0.615, 95% CI 0.429 to 0.881) and per cent of forced expiratory volume in 1 s (FEV1%) (HR=0.979, 95% CI 0.967 to 0.991), were independent risk factors for mortality.

CONCLUSIONS

Increased age, Charlson Index, chronic hypercapnia and Cor pulmonale, and decreased FEV1%, use of medication, BMI and NPPV, were associated with a poor prognosis in patients with COPD.

Emerging indications for extracorporeal membrane oxygenation in adults with respiratory failure

Recent advances in technology have spurred the increasing use of extracorporeal membrane oxygenation (ECMO) in patients with severe hypoxemic respiratory failure. However, this accounts for only a small percentage of patients with respiratory failure. We envision the application of ECMO in many other forms of respiratory failure in the coming years. Patients with less severe forms of acute respiratory distress syndrome, for instance, may benefit from enhanced lung-protective ventilation with the very low tidal volumes made possible by direct carbon dioxide removal from the blood. For those in whom hypercapnia predominates, extracorporeal support will allow for the elimination of invasive mechanical ventilation in some cases. The potential benefits of ECMO may be further enhanced by improved techniques, which facilitate active mobilization. Although ECMO for these and other expanded applications is under active investigation, it has yet to be proven beneficial in these settings in rigorous controlled trials. Ultimately, with upcoming and future technological advances, there is the promise of true destination therapy, which could lead to a major paradigm shift in the management of respiratory failure.

Early mobilization of patients receiving extracorporeal membrane oxygenation: a retrospective cohort study

Introduction

Critical illness is a well-recognized cause of neuromuscular weakness and impaired physical functioning. Physical therapy (PT) has been demonstrated to be safe and effective for critically ill patients. The impact of such an intervention on patients receiving extracorporeal membrane oxygenation (ECMO) has not been well characterized. We describe the feasibility and impact of active PT on ECMO patients.

Methods

We performed a retrospective cohort study of 100 consecutive patients receiving ECMO in the medical intensive care unit of a university hospital.

Results

Of the 100 patients receiving ECMO, 35 (35%) participated in active PT; 19 as bridge to transplant and 16 as bridge to recovery. Duration of ECMO was 14.3 ± 10.9 days. Patients received 7.2 ± 6.5 PT sessions while on ECMO. During PT sessions, 18 patients (51%) ambulated (median distance 175 feet, range 4 to 2,800) and 9 patients were on vasopressors. Whilst receiving ECMO, 23 patients were liberated from invasive mechanical ventilation. Of the 16 bridge to recovery patients, 14 (88%) survived to discharge; 10 bridge to transplant patients (53%) survived to transplantation, with 9 (90%) surviving to discharge. Of the 23 survivors, 13 (57%) went directly home, 8 (35%) went to acute rehabilitation, and 2 (9%) went to subacute rehabilitation. There were no PT-related complications.

Conclusions

Active PT, including ambulation, can be achieved safely and reliably in ECMO patients when an experienced, multidisciplinary team is utilized. More research is needed to define the barriers to PT and the impact on survival and long-term functional, neurocognitive outcomes in this population.

Ventilator settings and monitoring parameter targets for initiation of continuous mandatory ventilation: a questionnaire study

PURPOSE

To inform development of educational tools, we sought to identify initial ventilator settings and monitoring targets for 3 scenarios.

METHOD

A survey was e-mailed to Canadian Society of Respiratory Therapists members with 2 reminders in March/April 2011.

RESULTS

Total evaluable surveys were 363. More participants selected pressure as opposed to volume ventilation for acute respiratory distress syndrome (ARDS; 77%) than for chronic obstructive pulmonary disease (COPD; 50%) and postoperative ventilation (32%; P < .001). Mean tidal volume was lower for ARDS than for COPD and postoperative ventilation (5.7, 6.9, and 7.2 mL/kg, respectively; P < .001). Maximum acceptable plateau pressures were highest for ARDS (30 cm H2O vs 29 cm H2O [COPD] and 27 cm H2O [postoperative], P < .001). Initial positive expiratory end pressure (12 cm H2O vs 7 cm H2O vs 5 cm H2O) and fraction of inspired oxygen (Fio2; 1.0 vs 0.5 vs 0.3) were also higher for ARDS (both P < .001); however, only 8% selected a positive expiratory end pressure/Fio2 combination as recommended by ARDSnet. Values of oxygen saturation as measured by pulse oximetry of 97% (ARDS) and 94% (COPD and postoperative) were considered appropriate for Fio2 reduction. The lowest pH was 7.28 vs 7.23 vs 7.26; the highest pH was 7.46 vs 7.44 vs 7.46 (P < .001). Partial pressure of carbon dioxide (arterial) of 51 mm Hg (postoperative) to 65 mm Hg (ARDS) was considered acceptable.

CONCLUSION

Lung protective ventilation was favored, yet distinct differences in ventilator settings were evident. Monitoring targets suggested relatively conservative practices for Fio2 reduction but an understanding of permissive hypercapnia.

Acute respiratory failure and intensive measures

Critical patients presenting with acute respiratory failure (ARF) offer a plentiful, dynamic, and complex picture, which requires a deep understanding of gas exchange, pulmonary dynamics, and mechanical ventilation strategies. The most frequent cause of ARF is chronic disease with exacerbation. Interventions treating acute exacerbation, along with ventilatory support, physical therapy, and evidence-based strategies, may improve immediate outcomes. However, follow-up is essential and for the chronic obstructive pulmonary disease patient the goal is to avoid relapse or rehospitalization. This article discusses the evaluation of gas exchange failures, pulmonary mechanics, and the properties of obstructive airway disease as they relate to ARF.

[Invasive mechanical ventilation in COPD and asthma]

COPD and asthmatic patients use a substantial proportion of mechanical ventilation in the ICU, and their overall mortality with ventilatory support can be significant. From the pathophysiological standpoint, they have increased airway resistance, pulmonary hyperinflation, and high pulmonary dead space, leading to increased work of breathing. If ventilatory demand exceeds work output of the respiratory muscles, acute respiratory failure follows. The main goal of mechanical ventilation in this kind of patients is to improve pulmonary gas exchange and to allow for sufficient rest of compromised respiratory muscles to recover from the fatigued state. The current evidence supports the use of noninvasive positive-pressure ventilation for these patients (especially in COPD), but invasive ventilation also is required frequently in patients who have more severe disease. The physician must be cautious to avoid complications related to mechanical ventilation during ventilatory support. One major cause of the morbidity and mortality arising during mechanical ventilation in these patients is excessive dynamic pulmonary hyperinflation (DH) with intrinsic positive end-expiratory pressure (intrinsic PEEP or auto-PEEP). The purpose of this article is to provide a concise update of the most relevant aspects for the optimal ventilatory management in these patients.

Mechanical Ventilation

Mechanical ventilation is a common therapeutic modality required for the management of patients unable to maintain adequate intrinsic ventilation and oxygenation. Mechanical ventilators can be found within various hospital and nonhospital environments (ie, nursing homes, skilled nursing facilities, and patient’s home residence), but these devices generally require the skill of a multidisciplinary health care team to optimize therapeutic outcomes. Unfortunately, pharmacists have been excluded in the discussion of mechanical ventilation since this therapeutic modality may be perceived as irrelevant to drug utilization and the usual scope of practice of a hospital pharmacist. However, the pharmacist provides a crucial role as a member of the multidisciplinary team in the management of the mechanically ventilated patient by verifying accuracy of prescribed medications, providing recommendations of alternative drug selections, monitoring for drug and disease interactions, assisting in the development of institutional weaning protocols, and providing quality assessment of drug utilization. Pharmacists may be intimidated by the introduction of advanced ventilator microprocessor technology, but understanding and integrating ventilator management with the pharmacotherapeutic needs of the patient will ultimately help the pharmacist be a better qualified and respected practitioner. The goal of this article is to assist the pharmacy practitioner with a better understanding of mechanical ventilation and to apply this information to improve delivery of pharmaceutical care.

Use of invasive mechanical ventilation in Australian emergency departments

OBJECTIVE

There are few published reports describing the use of invasive mechanical ventilation in EDs. We explored the characteristics of patients receiving mechanical ventilation, the ventilator modes and parameters used as well as the duration of ventilation and the nature of ventilator decision-making in Australian ED.

METHODS

We conducted a 2 month prospective survey of adult patients who received invasive mechanical ventilation in 24 Australian ED. Data forms were completed by ED staff during the patient's ED presentation. We documented ventilator settings post intubation, after a 1 h stabilization period, and immediately before ED discharge or extubation. The person responsible for selection of ventilator settings was noted at each time point.

RESULTS

Data were recorded on 307 patients. Altered mental status (179/307 [58%, 95% CI 53-64]) was the most common indication for mechanical ventilation. Volume-controlled modes were most frequently used at all measured time points; with a median tidal volume of 8 mL/kg. Responsibility for initial selection of ventilator settings was shared between ED physicians (157/307 [51%, 95% CI 46-57]), ED nurses (111/307 [36%, 95% CI 31-42]) and ICU or paramedic staff (9/307 [3%, 95% CI 1-5]) (not recorded 30/307 [10%, 95% CI 6-13]). Ongoing responsibility for titration of ventilation was more commonly that of the ED nurse.

CONCLUSION

The application of mechanical ventilation was similar to descriptions reported in the critical care literature both in Australia and internationally. Decision-making responsibilities were shared by ED medical and nursing staff.

Venovenous carbon dioxide removal in chronic obstructive pulmonary disease: experience in one patient

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States. Acute exacerbations of COPD account for up to 84% of the total economic cost of this disease. The altered mechanics of the COPD patient represent a unique challenge to the clinician instituting assisted ventilation in this population. We developed an alternative mode of limited extracorporeal support termed Venovenous carbon dioxide removal (VVCO2R). We report our first case using VVCO2R, a 42-year-old white woman with a history of COPD and asthma, who was a heavy smoker at the time of admission. We utilized a compact, low flow pediatric extracorporeal circuit interposed with a low resistance gas exchange device. Venovenous carbon dioxide removal allowed for a reduction in the patient's minute ventilation to 30% of baseline with improved arterial blood gases (ABGs), a reduction in peak airway pressures and improvement in her hyperinflation. Our experience demonstrates that this system can effectively remove CO2 safely in a single cannula venous configuration while maintaining minimal anticoagulation. We believe this system could potentially be utilized in any medical or surgical intensive care unit.

Post-ischemic helium provides neuroprotection in rats subjected to middle cerebral artery occlusion-induced ischemia by producing hypothermia

During the past decade, studies on the manipulation of various inhaled inert gases during ischemia and/or reperfusion have led to the conclusion that inert gases may be promising agents for treating acute ischemic stroke and perinatal hypoxia-ischemia insults. Although there is a general consensus that among these gases xenon is a golden standard, the possible widespread clinical use of xenon experiences major obstacles, namely its availability and cost of production. Interestingly, recent findings have shown that helium, which is a cost-efficient inert gas with no anesthetic properties, can provide neuroprotection against acute ischemic stroke in vivo when administered during ischemia and early reperfusion. We have investigated whether helium provides neuroprotection in rats subjected to middle cerebral artery occlusion (MCAO) when administered after reperfusion, a condition prerequisite for the therapeutic viability and possible clinical use of helium. In this study, we show that helium at 75 vol% produces neuroprotection and improvement of neurologic outcome in rats subjected to transient MCAO by producing hypothermia on account of its high specific heat as compared with air.

Treatment of respiratory failure in COPD

Patients with advanced COPD and acute or chronic respiratory failure are at high risk for death. Beyond pharmacological treatment, supplemental oxygen and mechanical ventilation are major treatment options. This review describes the physiological concepts underlying respiratory failure and its therapy, as well as important treatment outcomes. The rationale for the controlled supply of oxygen in acute hypoxic respiratory failure is undisputed. There is also a clear survival benefit from long-term oxygen therapy in patients with chronic hypoxia, while in mild, nocturnal, or exercise-induced hypoxemia such long-term benefits appear questionable. Furthermore, much evidence supports the use of non-invasive positive pressure ventilation in acute hypercapnic respiratory failure. It application reduces intubation and mortality rates, and the duration of intensive care unit or hospital stays, particularly in the presence of mild to moderate respiratory acidosis. COPD with chronic hypercapnic respiratory failure became a major indication for domiciliary mechanical ventilation, based on pathophysiological reasoning and on data regarding symptoms and quality of life. Still, however, its relevance for long-term survival has to be substantiated in prospective controlled studies. Such studies might preferentially recruit patients with repeated hypercapnic decompensation or a high risk for death, while ensuring effective ventilation and the patients’ adherence to therapy.