The acute effects of body position strategies and respiratory therapy in paralyzed patients with acute lung injury

Recovery of severe COVID-19 complicated with cerebral infarction: Considerations on a case report

RATIONALE

The standardization, individualization, and rationalization of intensive care and treatment for severe patients have improved. However, the combination of corona virus disease 2019 (COVID-19) and cerebral infarction presents new challenges beyond routine nursing care.

PATIENT CONCERNS AND DIAGNOSES

This paper examines the rehabilitation nursing of patients with both COVID-19 and cerebral infarction as an example. It is necessary to develop a nursing plan for COVID-19 patients and implement early rehabilitation nursing for cerebral infarction patients.

INTERVENTIONS

Timely rehabilitation nursing intervention is essential to enhance treatment outcomes and promote patient rehabilitation. After 20 days of rehabilitation nursing treatment, patients showed significant improvement in visual analogue scale score, drinking test, and upper and lower limb muscle strength.

OUTCOMES

Treatment outcomes for complications, motor function, and daily activities also improved significantly.

LESSONS

Critical care and rehabilitation specialist care play a positive role in ensuring patient safety and improving their quality of life by adapting measures to local conditions and the timing of care.

Initial assessment and management of respiratory infections in persons with spinal cord injuries and disorders in the COVID-19 era

As the COVID-19 pandemic unfolds, emergency department (ED) personnel will face a higher caseload, including those with special medical needs such as persons living with spinal cord injuries and disorders (SCI/D). Individuals with SCI/D who develop COVID-19 are at higher risk for rapid decompensation and development of acute respiratory failure during respiratory infections due to the combination of chronic respiratory muscle paralysis and autonomic dysregulation causing neurogenic restrictive/obstructive lung disease and chronic immune dysfunction. Often, acute respiratory infections will lead to significant mucus production in individuals with SCI/D, and aggressive secretion management is an important component of successful medical treatment. Secretion management techniques include nebulized bronchodilators, chest percussion/drainage techniques, manually assisted coughing techniques, nasotracheal suctioning, and mechanical insufflation-exsufflation. ED professionals, including respiratory therapists, should be familiar with the significant comorbidities associated with SCI/D and the customized secretion management procedures and techniques required for optimal medical management and prevention of respiratory failure. Importantly, protocols should also be implemented to minimize potential COVID-19 spread during aerosol-generating procedures.

Lateral positioning for critically ill adult patients

BACKGROUND

Critically ill patients require regular body position changes to minimize the adverse effects of bed rest, inactivity and immobilization. However, uncertainty surrounds the effectiveness of lateral positioning for improving pulmonary gas exchange, aiding drainage of tracheobronchial secretions and preventing morbidity. In addition, it is unclear whether the perceived risk levied by respiratory and haemodynamic instability upon turning critically ill patients outweighs the respiratory benefits of side-to-side rotation. Thus, lack of certainty may contribute to variation in positioning practice and equivocal patient outcomes.

OBJECTIVES

To evaluate effects of the lateral position compared with other body positions on patient outcomes (mortality, morbidity and clinical adverse events) in critically ill adult patients. (Clinical adverse events include hypoxaemia, hypotension, low oxygen delivery and global indicators of impaired tissue oxygenation.) We examined single use of the lateral position (i.e. on the right or left side) and repeat use of the lateral position (i.e. lateral positioning) within a positioning schedule.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 5), MEDLINE (1950 to 23 May 2015), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1937 to 23 May 2015), the Allied and Complementary Medicine Database (AMED) (1984 to 23 May 2015), Latin American Caribbean Health Sciences Literature (LILACS) (1901 to 23 May 2015), Web of Science (1945 to 23 May 2015), Index to Theses in Great Britain and Ireland (1950 to 23 May 2015), Trove (2009 to 23 May 2015; previously Australasian Digital Theses Program (1997 to December 2008)) and Proquest Dissertations and Theses (2009 to 23 May 2015; previously Proquest Digital Dissertations (1980 to 23 May 2015)). We handsearched the reference lists of potentially relevant reports and two nursing journals.

SELECTION CRITERIA

We included randomized and quasi-randomized trials examining effects of lateral positioning in critically ill adults. We included manual or automated turns but limited eligibility to studies that included duration of body position of 10 minutes or longer. We examined each lateral position versus at least one comparator (opposite lateral position and/or another body position) for single therapy effects, and the lateral positioning schedule (repeated lateral turning) versus other positioning schedules for repetitive therapy effects.

DATA COLLECTION AND ANALYSIS

We pre-specified methods to be used for data collection, risk of bias assessment and analysis. Two independent review authors carried out each stage of selection and data extraction and settled differences in opinion by consensus, or by third party adjudication when disagreements remained unresolved. We planned analysis of pair-wise comparisons under composite time intervals with the aim of considering recommendations based on meta-analyses of studies with low risk of bias.

MAIN RESULTS

We included 24 studies of critically ill adults. No study reported mortality as an outcome of interest. Two randomized controlled trials (RCTs) examined lateral positioning for pulmonary morbidity outcomes but provided insufficient information for meta-analysis. A total of 22 randomized trials examined effects of lateral positioning (four parallel-group and 18 cross-over designs) by measuring various continuous data outcomes commonly used to detect adverse cardiopulmonary events within critical care areas. However, parallel-group studies were not comparable, and cross-over studies provided limited data as the result of unit of analysis errors. Eight studies provided some data; most of these were single studies with small effects that were imprecise. We pooled partial pressure of arterial oxygen (PaO2) as a measure to detect hypoxaemia from two small studies of participants with unilateral lung disease (n = 19). The mean difference (MD) between lateral positions (bad lung down versus good lung down) was approximately 50 mmHg (MD -49.26 mmHg, 95% confidence interval (CI) -67.33 to -31.18; P value < 0.00001). Despite a lower mean PaO2 for bad lung down, hypoxaemia (mean PaO2 < 60 mmHg) was not consistently reported. Furthermore, pooled data had methodological shortcomings with unclear risk of bias. We had similar doubts regarding internal validity for other studies included in the review.

AUTHORS' CONCLUSIONS

Review authors could provide no clinical practice recommendations based on the findings of included studies. Available research could not eliminate the uncertainty surrounding benefits and/or risks associated with lateral positioning of critically ill adult patients. Research gaps include the effectiveness of lateral positioning compared with semi recumbent positioning for mechanically ventilated patients, lateral positioning compared with prone positioning for acute respiratory distress syndrome (ARDS) and less frequent changes in body position. We recommend that future research be undertaken to address whether the routine practice of repositioning patients on their side benefits all, some or few critically ill patients.

[Manual airway clearance techniques in adults and adolescents: What level of evidence?]

BACKGROUND

The aim of this systematic literature review was to grade the levels of evidence of the most widely used manual airway clearance techniques.

METHODS

A literature search was conducted over the period 1995-2014 from the Medline, PEDro, ScienceDirect, Cochrane Library, REEDOC and kinedoc databases, with the following keywords: "postural drainage", "manual vibrations", "manual chest percussion", "directed cough", "increased expiratory flow", "ELTGOL", "autogenic drainage" and "active cycle of breathing technique".

RESULTS

Two-hundred and fifty-six articles were identified. After removing duplicates and reading the titles and abstracts, 63 articles were selected, including 9 systematic reviews. This work highlights the lack of useful scientific data and the difficulty of determining levels of evidence for manual airway clearance techniques. Techniques were assessed principally with patients with sputum production (cystic fibrosis, DDB, COPD, etc.). It also shows the limited pertinence of outcome measures to quantify congestion and hence the efficacy of airway clearance techniques.

CONCLUSION

The 1994 consensus conference summary table classifying airway clearance techniques according to physical mechanism provides an interesting tool for assessment, grouping together techniques having identical mechanisms of action. From the findings of the present systematic review, it appears that only ELTGOL, autogenic drainage and ACBT present levels of evidence "B". All other techniques have lower levels of evidence.

LEVEL OF EVIDENCE

II.

Experimental blunt chest trauma--cardiorespiratory effects of different mechanical ventilation strategies with high positive end-expiratory pressure: a randomized controlled study

Background

Uncertainty persists regarding the optimal ventilatory strategy in trauma patients developing acute respiratory distress syndrome (ARDS). This work aims to assess the effects of two mechanical ventilation strategies with high positive end-expiratory pressure (PEEP) in experimental ARDS following blunt chest trauma.

Methods

Twenty-six juvenile pigs were anesthetized, tracheotomized and mechanically ventilated. A contusion was applied to the right chest using a bolt-shot device. Ninety minutes after contusion, animals were randomized to two different ventilation modes, applied for 24 h: Twelve pigs received conventional pressure-controlled ventilation with moderately low tidal volumes (V_T, 8 ml/kg) and empirically chosen high external PEEP (16cmH₂O) and are referred to as the HP-CMV-group. The other group (n = 14) underwent high-frequency inverse-ratio pressure-controlled ventilation (HFPPV) involving respiratory rate of 65breaths · min⁻¹, inspiratory-to-expiratory-ratio 2:1, development of intrinsic PEEP and recruitment maneuvers, compatible with the rationale of the Open Lung Concept. Hemodynamics, gas exchange and respiratory mechanics were monitored during 24 h. Computed tomography and histology were analyzed in subgroups.

Results

Comparing changes which occurred from randomization (90 min after chest trauma) over the 24-h treatment period, groups differed statistically significantly (all P values for group effect <0.001, General Linear Model analysis) for the following parameters (values are mean ± SD for randomization vs. 24-h): PaO₂ (100 % O₂) (HFPPV 186 ± 82 vs. 450 ± 59 mmHg; HP-CMV 249 ± 73 vs. 243 ± 81 mmHg), venous admixture (HFPPV 34 ± 9.8 vs. 11.2 ± 3.7 %; HP-CMV 33.9 ± 10.5 vs. 21.8 ± 7.2 %), PaCO₂ (HFPPV 46.9 ± 6.8 vs. 33.1 ± 2.4 mmHg; HP-CMV 46.3 ± 11.9 vs. 59.7 ± 18.3 mmHg) and normally aerated lung mass (HFPPV 42.8 ± 11.8 vs. 74.6 ± 10.0 %; HP-CMV 40.7 ± 8.6 vs. 53.4 ± 11.6 %). Improvements occurring after recruitment in the HFPPV-group persisted throughout the study. Peak airway pressure and V_T did not differ significantly. HFPPV animals had lower atelectasis and inflammation scores in gravity-dependent lung areas.

Conclusions

In this model of ARDS following unilateral blunt chest trauma, HFPPV ventilation improved respiratory function and fulfilled relevant ventilation endpoints for trauma patients, i.e. restoration of oxygenation and lung aeration while avoiding hypercapnia and respiratory acidosis.

S2e guideline: positioning and early mobilisation in prophylaxis or therapy of pulmonary disorders : Revision 2015: S2e guideline of the German Society of Anaesthesiology and Intensive Care Medicine (DGAI)

The German Society of Anesthesiology and Intensive Care Medicine (DGAI) commissioneda revision of the S2 guidelines on "positioning therapy for prophylaxis or therapy of pulmonary function disorders" from 2008. Because of the increasing clinical and scientificrelevance the guidelines were extended to include the issue of "early mobilization"and the following main topics are therefore included: use of positioning therapy and earlymobilization for prophylaxis and therapy of pulmonary function disorders, undesired effects and complications of positioning therapy and early mobilization as well as practical aspects of the use of positioning therapy and early mobilization. These guidelines are the result of a systematic literature search and the subsequent critical evaluation of the evidence with scientific methods. The methodological approach for the process of development of the guidelines followed the requirements of evidence-based medicine, as defined as the standard by the Association of the Scientific Medical Societies in Germany. Recently published articles after 2005 were examined with respect to positioning therapy and the recently accepted aspect of early mobilization incorporates all literature published up to June 2014.

Infection control in the intensive care unit

It is critical for health care personnel to recognize and appreciate the detrimental impact of intensive care unit (ICU)-acquired infections. The economic, clinical, and social expenses to patients and hospitals are overwhelming. To limit the incidence of ICU-acquired infections, aggressive infection control measures must be implemented and enforced. Researchers and national committees have developed and continue to develop evidence-based guidelines to control ICU infections. A multifaceted approach, including infection prevention committees, antimicrobial stewardship programs, daily reassessments-intervention bundles, identifying and minimizing risk factors, and continuing staff education programs, is essential. Infection control in the ICU is an evolving area of critical care research.

Clinical practice guidelines for hospital-acquired pneumonia and ventilator-associated pneumonia in adults

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are important causes of morbidity and mortality, with mortality rates approaching 62%. HAP and VAP are the second most common cause of nosocomial infection overall, but are the most common cause documented in the intensive care unit setting. In addition, HAP and VAP produce the highest mortality associated with nosocomial infection. As a result, evidence-based guidelines were prepared detailing the epidemiology, microbial etiology, risk factors and clinical manifestations of HAP and VAP. Furthermore, an approach based on the available data, expert opinion and current practice for the provision of care within the Canadian health care system was used to determine risk stratification schemas to enable appropriate diagnosis, antimicrobial management and nonantimicrobial management of HAP and VAP. Finally, prevention and risk-reduction strategies to reduce the risk of acquiring these infections were collated. Future initiatives to enhance more rapid diagnosis and to effect better treatment for resistant pathogens are necessary to reduce morbidity and improve survival.

A study of ventilator-associated pneumonia: Incidence, outcome, risk factors and measures to be taken for prevention

Ventilator-associated pneumonia (VAP) is a major cause of hospital morbidity and mortality despite recent advances in diagnosis and accuracy of management. However, as taught in medical science, prevention is better than cure is probably more appropriate as concerned to VAP because of the fact that it is a well preventable disease and a proper approach decreases the hospital stay, cost, morbidity and mortality. The aim of the study is to critically review the incidence and outcome, identify various risk factors and conclude specific measures that should be undertaken to prevent VAP. We studied 100 patients randomly, kept on ventilatory support for more than 48 h. After excluding those who developed pneumonia within 48 h, VAP was diagnosed when a score of ≥6 was obtained in the clinical pulmonary infection scoring system having six variables and a maximum score of 12. After evaluating, the data were subjected to univariate analysis using the chi-square test. The level of significance was set at P<0.05. It was found that 37 patients developed VAP. The risk factor significantly associated with VAP in our study was found to be duration of ventilator support, reintubation, supine position, advanced age and altered consciousness. Declining ratio of partial pressure to inspired fraction of oxygen (PaO₂/FiO₂ ratio) was found to be the earliest indicator of VAP. The most common organism isolated in our institution was Pseudomonas. The incidence of early-onset VAP (within 96 h) was found to be 27% while the late-onset type (>96 h) was 73%. Late-onset VAP had poor prognosis in terms of mortality (66%) as compared to the early-onset type (20%). The mortality of patients of the non-VAP group was found to be 41% while that of VAP patients was 54%. Targeted strategies aimed at preventing VAP should be implemented to improve patient outcome and reduce length of intensive care unit stay and costs. Above all, everyone of the critical care unit should understand the factors that place the patients at risk of VAP and utmost importance must be given to prevent VAP.

Physiotherapy secretion removal techniques in people with spinal cord injury: a systematic review

OBJECTIVE

To address whether secretion removal techniques increase airway clearance in people with chronic spinal cord injury (SCI).

DATA SOURCES AND STUDY SELECTION

MEDLINE/PubMed, CINAHL, EMBASE, and PsycINFO were searched from inception to May 2009 for population keywords (spinal cord injury, paraplegia, tetraplegia, quadriplegia) paired with secretion removal-related interventions and outcomes. Inclusion criteria for articles were a research study, irrespective of design, that examined secretion removal in people with chronic SCI published in English.

REVIEW METHODS

Two reviewers determined whether articles met the inclusion criteria, abstracted information, and performed a quality assessment using PEDro or Downs and Black criteria. Studies were then given a level of evidence based on a modified Sackett scale.

RESULTS

Of 2416 abstracts and titles retrieved, 24 met the inclusion criteria. Subjects were young (mean, 31 years) and 84% were male. Most evidence was level 4 or 5 and only 2 studies were randomized controlled trials. Three reports described outcomes for secretion removal techniques in addition to cough, whereas most articles examined the immediate effects of various components of cough. Studies examining insufflation combined with manual assisted cough provided the most consistent, high-level evidence. Compelling recent evidence supports the use of respiratory muscle training or electrical stimulation of the expiratory muscles to facilitate airway clearance in people with SCI.

CONCLUSION

Evidence supporting the use of secretion removal techniques in SCI, while positive, is limited and mostly of low level. Treatments that increase respiratory muscle force show promise as effective airway clearance techniques.

Infections in the Intensive Care Unit

After studying this chapter, you should be able to: Understand the pathophysiology of specific infections in the ICU. Identify infectious complications in critically ill patients. Conduct appropriate diagnostic work-up for infections encountered in the ICU. Develop a systematic approach for managing ICU-related infections. Execute effective measures to prevent infectious complications in the ICU. Understand how to effectively work up and treat patients with sepsis. Choose the appropriate antimicrobial regimen for either empiric or culture-focused treatment of ICU infections.

Is there evidence to support the use of lateral positioning in intensive care? A systematic review

A systematic review of randomised clinical trials was conducted to investigate the efficacy and safety of use of the lateral position in the management of ventilated intensive care patients. One review article and 11 empiric studies, which were mostly of low methodological quality, met the eligibility criteria. Large individual variations in PaO2 response to lateral positioning were demonstrated. Greatest improvement in PaO2 occurred in patients with unilateralpulmonary infiltrates positioned with the bad lung up versus bad lung down (average difference = 33.6 mmHg (range 0-58), effect size 1.13 (95% CI: 0.44, 1.19, P = 0.001)) or supine (average difference=27 mmHg (range 5-42), effect size 0.58 (95% CI: 0.11, 1.06, P = 0.017)). This effect appeared to be most prominent in patients with widespread, unilateral infiltrates. Lung compliance was not affected by lateral positioning. Haemodynamic compromise was evident with lateral positioning of greater than 60 degrees to the right side in patients requiring vasopressors and/or with right ventricular dysfunction; or with lateral positioning in postoperative coronary artery bypass graft patients. No studies were found that had investigated the effect of routine applications of the lateral positioning to improve, prevent or treat pneumonia, decrease mortality or influence other long-term outcomes. The results of this review demonstrate the limited evidence available to support the use of lateral positioning in the intensive care environment. More data reporting the long-term effects of lateral position on long-term outcomes would aid clinical decision making and may improve the application of patient positioning in critical care environments.

Biomechanical Analysis of Cervical and Thoracolumbar Spine Motion in Intact and Partially and Completely Unstable Cadaver Spine Models With Kinetic Bed Therapy or Traditional Log Roll

BACKGROUND

The main comorbidities associated with spinal cord injury patients are secondary to immobilization. Kinetic bed therapy is used currently to reduce the complications associated with immobilization, but the effect on the unstable spine has not been quantified. The purpose of this study was to compare the motion in the cervical and thoracolumbar spine when cadavers with spinal instabilities are log rolled (LR) on a standard hospital bed or rotated on a RotoRest kinetic treatment table (KTT).

METHODS

Cervical and lumbar instabilities were created surgically in three embalmed cadavers. An electromagnetic tracking device was used to measure the three-dimensional segmental motion generated at C5 to C6 and T12 to L2 during LR and KTT treatments.

RESULTS

In both the cervical and lumbar spine, significantly more motion was observed during LR than KTT treatment.

CONCLUSIONS

We found that in cadavers with severely unstable cervical spine, rotation using a KTT produced less flexion and lateral bending than the LR. Also, in cadavers with severely unstable lumbar spine, treatment with the KTT produced less axial rotation than the LR. Currently, we think that the best way to immobilize the spine while still allowing therapeutic motion is through the use of a KTT.

Rotational Bed Therapy to Prevent and Treat Respiratory Complications: A Review and Meta-Analysis

• Background Immobility is associated with complications involving many body systems.

• Objective To review the effect of rotational therapy (use of therapeutic surfaces that turn on their longitudinal axes) on prevention and/or treatment of respiratory complications in critically ill patients.

• Methods Published articles evaluating prophylaxis and/or treatment were reviewed. Prospective randomized controlled trials were assessed for quality and included in meta-analyses.

• Results A literature search yielded 15 nonrandomized, uncontrolled, or retrospective studies. Twenty prospective randomized controlled trials on rotational therapy were published between 1987 and 2004. Various types of beds were studied, but few details on the rotational parameters were reported. The usual control was manual turning of patients by nurses every 2 hours. One animal investigation and 12 clinical trials addressed the effectiveness of rotational therapy in preventing respiratory complications. Significant benefits were reported in the animal study and 4 of the trials. Significant benefits to patients were reported in 2 of another 4 studies focused on treatment of established complications. Researchers have examined the effects of rotational therapy on mucus transport, intrapulmonary shunt, hemodynamic effects, urine output, and intracranial pressure. Little convincing evidence is available, however, on the most effective rotation parameters (eg, degree, pause time, and amount of time per day). Meta-analysis suggests that rotational therapy decreases the incidence of pneumonia but has no effect on duration of mechanical ventilation, number of days in intensive care, or hospital mortality.

• Conclusions Rotational therapy may be useful for preventing and treating respiratory complications in selected critically ill patients receiving mechanical ventilation.

Effect of expiratory flow increase technique on pulmonary function of infants on mechanical ventilation

BACKGROUND AND PURPOSE

Although chest physiotherapy techniques are commonly used in the treatment of respiratory diseases, there are, however, few studies in the literature on the effectiveness of these techniques in paediatric patients. The purpose of the present study was to evaluate the effect of the expiratory flow increase technique (EFIT) on the pulmonary function of infants on invasive mechanical pulmonary ventilation.

METHOD

A prospective, non-randomized study design was used, with consecutive enrolment conducted in the paediatric intensive care unit (PICU) of a university hospital. All infants with acute obstructive respiratory failure who were on invasive mechanical pulmonary ventilation between April 2001 and April 2003 were included in this study. Respiratory rate, PaO2, PaCO2, SatO2, PaO2/FiO2, P(A-a)O2/PaO2, PaO2/PAO2, VD/VT, dynamic compliance, inspiratory and expiratory resistance values were compared before and after application of the EFIT.

RESULTS

Blood gas and pulmonary function measurements were recorded before and after EFIT. Repeated-measures analysis of variance (ANOVA) was used. The results were considered statistically significant when p values were < 0.05. Twenty-two infants were enrolled. There was a significant increase in respiratory rate, SatO2 and PaO2/PAO2 and a significant decrease in P(A-a)O2/PaO2 after application of the EFIT.

CONCLUSION

There was a short-term improvement in the oxygenation of infants who were submitted to the EFIT. Additional studies are necessary to establish the efficacy and effectiveness of this technique.

Lateralización como alternativa al decúbito prono estático en pacientes con SDRA

According to Phillips, Continuous Lateral Rotation (CLR) or Kinetic Therapy (KT) together with the technological advances obtain some important benefits in mechanically ventilated patients.

OBJECTIVE

Compare Static Prone Decubitus (PD) with DP in CRL.

PATIENTS AND METHODS

We analyzed 2 groups with a total of 41 patients in the period of January 1998 to April 2003. The DP group (25 patients) remained static and the lateral group (16 patients) in CLR every 2 h. The groups had 56 +/- 16 vs 64 +/- 17 years, 77 +/- 20 vs 71 +/- 23 kg and 24% vs 31% of survival, respectively.

RESULTS

We maintained the PD 37 +/- 30 vs 27 +/- 36 h for group 1 and 2. The response as Responders is 68% and 69%. pO2/FiO2 of supine pre-DP to supine post-DP is 79 +/- 21 to 146 +/- 68 versus 80 +/- 20 to 138 +/- 57 and pulmonary compliance 22 +/- 10 to 21 +/- 10 vs 31 +/- 10 to 32 +/- 9. Mean blood pressure of S to S was 87 +/- 16 to 85 +/- 15 vs 82 +/- 10 to 80 +/- 9, and mean Heart rate 108 +/- 21 to 95 +/- 24 vs 85 +/- 32 to 75 +/- 28. Complications by groups were: facial edema of 84% vs 63%, gastric retention 36% to 38%, vomiting/regurgitation 12% to 0%, epistaxis 8% to 31%. Pressure Sore (PS) Incidence decreased from 36% to 12%, together with seriousness.

CONCLUSION

We consider that lateralization if PD is a technique comparable to static PD on the respiratory and hemodynamics level. CLR in PD may prevent some complications.

An advanced expiratory circuit for the recovery of perfluorocarbon liquid from non-saturated perfluorocarbon vapour during partial liquid ventilation: an experimental model

Background

The loss of perfluorocarbon (PFC) vapour in the expired gases during partial liquid ventilation should be minimized both to prevent perfluorocarbon vapour entering the atmosphere and to re-use the recovered PFC liquid.

Using a substantially modified design of our previously described condenser, we aimed to determine how much perfluorocarbon liquid could be recovered from gases containing PFC and water vapour, at concentrations found during partial liquid ventilation, and to determine if the amount recovered differed with background flow rate (at flow rates suitable for use in neonates).

Methods

The expiratory line of a standard ventilator circuit set-up was mimicked, with the addition of two condensers. Perfluorocarbon (30 mL of FC-77) and water vapour, at concentrations found during partial liquid ventilation, were passed through the circuit at a number of flow rates and the percentage recovery of the liquids measured.

Results

From 14.2 mL (47%) to 27.3 mL (91%) of the infused 30 mL of FC-77 was recovered at the flow rates studied. Significantly higher FC-77 recovery was obtained at lower flow rates (ANOVA with Bonferroni's multiple comparison test, p < 0.0001). As a percentage of the theoretical maximum recovery, 64 to 95% of the FC-77 was recovered. Statistically significantly less FC-77 was recovered at 5 Lmin^-1 (ANOVA with Bonferroni's multiple comparison test, p < 0.0001). Amounts of perfluorocarbon vapour recovered were 47%, 50%, 81% and 91% at flow rates of 10, 5, 2 and 1 Lmin^-1, respectively.

Conclusion

Using two condensers in series 47% to 91% of perfluorocarbon liquid can be recovered, from gases containing perfluorocarbon and water vapour, at concentrations found during partial liquid ventilation.

Science review: redox and oxygen-sensitive transcription factors in the regulation of oxidant-mediated lung injury: role for hypoxia-inducible factor-1alpha

A progressive rise of oxidative stress due to altered reduction-oxidation (redox) homeostasis appears to be one of the hallmarks of the processes that regulate gene transcription in physiology and pathophysiology. Reactive oxygen species and reactive nitrogen species serve as signaling messengers for the evolution and perpetuation of the inflammatory process that is often associated with the condition of oxidative stress, which involves genetic regulation. Changes in the pattern of gene expression through reactive oxygen species/reactive nitrogen species-sensitive regulatory transcription factors are crucial components of the machinery that determines cellular responses to oxidative/redox conditions. The present review describes the basic components of the intracellular oxidative/redox control machinery and its crucial regulation of oxygen-sensitive and redox-sensitive transcription factors within the context of lung injury. Particularly, the review discusses mechanical ventilation and NF-kappaB-mediated lung injury, ischemia-reperfusion and transplantation, compromised host defense and inflammatory stimuli, and hypoxemia and the crucial role of hypoxia-inducible factor in mediating lung injury. Changes in the pattern of gene expression through regulatory transcription factors are therefore crucial components of the machinery that determines cellular responses to oxidative/redox stress.