Prone-position ventilation induces sustained improvement in oxygenation in patients with acute respiratory distress syndrome who have a large shunt

Case report: Inhaled nitric oxide rescued a hypoxemia patient caused by dermatomyositis complicated with interstitial pneumonia

Interstitial pneumonia is the most common and serious secondary lesion of dermatomyositis. In some cases, patients may develop severe acute pneumonia that can quickly progress to respiratory failure, resulting in high mortality rates. A 57-year-old woman with dermatomyositis and interstitial pulmonary fibrosis experienced severe hypoxemia due to pulmonary infection. Despite receiving various treatments after entering the intensive care unit (ICU), such as anti-infection therapy, lung recruitment, prone position ventilation, sedative and muscle relaxation, the patient's oxygen saturation continued to decline. Electrical impedance tomography (EIT) monitoring revealed that prone position could not improve ventilation homogeneity. However, the patient's ventilation/perfusion (V/Q) matching significantly improved 10 min after initiation of supine position ventilation combined with inhalation of nitric oxide (iNO). The patient's PaO2/FiO2 (P/F) ratio increased from 86 mmHg to 150 mmHg at 30 min post-treatment. iNO treatment continued for 2 days. Then the patient's condition improved and she was successfully weaned off the ventilator with rigorous monitoring and symptomatic care. The implementation of mechanical ventilation combined with iNO therapy rapidly improved V/Q matching and oxygenation in a patient with hypoxemia caused by dermatomyositis complicated with interstitial pneumonia. This approach successfully avoided the need for invasive extracorporeal membrane oxygenation (ECMO) support.

Approach to echocardiography in ARDS patients in the prone position: A systematic review

Echocardiography is commonly utilized in patients with acute respiratory distress syndrome (ARDS) for assessment of cardiac function, volume status, and the potential development of acute cor pulmonale. In severe ARDS, prone positioning is frequently used, which imposes technical challenges during transthoracic echocardiography (TTE) image acquisition. Moreover, prone positioning can affect cardiopulmonary function in ways that are reflected on the echocardiographic findings in this position. Historically, a transesophageal approach was recommended when a patient is prone, with few studies reporting utility of TTE in this setting. However, recent publications have begun to address this knowledge gap. This review explores recent literature addressing the use of TTE in prone patients with ARDS, with a special focus on the cardiopulmonary effects of proning and potential solutions to the technical difficulties that arise in this position.

Therapeutic benefits of proning to improve pulmonary gas exchange in severe respiratory failure: focus on fundamentals of physiology

New Findings

What is the topic of this review?

The use of proning for improving pulmonary gas exchange in critically ill patients.

What advances does it highlight?

Proning places the lung in its ‘natural’ posture, and thus optimises the ventilation‐perfusion distribution, which enables lung protective ventilation and the alleviation of potentially life‐threatening hypoxaemia in COVID‐19 and other types of critical illness with respiratory failure.

Abstract

The survival benefit of proning patients with acute respiratory distress syndrome (ARDS) is well established and has recently been found to improve pulmonary gas exchange in patients with COVID‐19‐associated ARDS (CARDS). This review outlines the physiological implications of transitioning from supine to prone on alveolar ventilation‐perfusion (V˙A--Q˙) relationships during spontaneous breathing and during general anaesthesia in the healthy state, as well as during invasive mechanical ventilation in patients with ARDS and CARDS. Spontaneously breathing, awake healthy individuals maintain a small vertical (ventral‐to‐dorsal) V˙A/Q˙ ratio gradient in the supine position, which is largely neutralised in the prone position, mainly through redistribution of perfusion. In anaesthetised and mechanically ventilated healthy individuals, a vertical V˙A/Q˙ ratio gradient is present in both postures, but with better V˙A--Q˙ matching in the prone position. In ARDS and CARDS, the vertical V˙A/Q˙ ratio gradient in the supine position becomes larger, with intrapulmonary shunting in gravitationally dependent lung regions due to compression atelectasis of the dorsal lung. This is counteracted by proning, mainly through a more homogeneous distribution of ventilation combined with a largely unaffected high perfusion dorsally, and a consequent substantial improvement in arterial oxygenation. The data regarding proning as a therapy in patients with CARDS is still limited and whether the associated improvement in arterial oxygenation translates to a survival benefit remains unknown. Proning is nonetheless an attractive and lung protective manoeuvre with the potential benefit of improving life‐threatening hypoxaemia in patients with ARDS and CARDS.

Hemodynamic effects of extended prone position sessions in ARDS

Background

Hemodynamic response to prone position (PP) has never been studied in a large series of patients with acute respiratory distress syndrome (ARDS). The primary aim of this study was to estimate the rate of PP sessions associated with cardiac index improvement. Secondary objective was to describe hemodynamic response to PP and during the shift from PP to supine position.

Methods

The study was a single-center retrospective observational study, performed on ARDS patients, undergoing at least one PP session under monitoring by transpulmonary thermodilution. PP sessions performed more than 10 days after ARDS onset, or with any missing cardiac index measurements before (T₁), at the end (T₃), and after the PP session (T₄) were excluded. Changes in hemodynamic parameters during PP were tested after statistical adjustment for volume of fluid challenges, vasopressor and dobutamine dose at each time point to take into account therapeutic changes during PP sessions.

Results

In total, 107 patients fulfilled the inclusion criteria, totalizing 197 PP sessions. Changes in cardiac index between T₁ and T₂ (early response to PP) and between T₁ and T₃ (late response to PP) were significantly correlated (R² = 0.42, p < 0.001) with a concordance rate amounting to 85%. Cardiac index increased significantly between T₁ and T₃ in 49 sessions (25% [95% confidence interval (CI_95%) 18–32%]), decreased significantly in 46 (23% [CI_95% 16–31%]), and remained stable in 102 (52% [CI_95% 45–59%]). Global end-diastolic volume index (GEDVI) increased slightly but significantly from 719 ± 193 mL m⁻² at T₁ to 757 ± 209 mL m⁻² at T₃ and returned to baseline values at T₄. Cardiac index and oxygen delivery decreased slightly but significantly from T₃ to T₄, without detectable increase in lactate level. Patients who increased their cardiac index during PP had significantly lower CI, GEDVI, global ejection fraction at T₁, and received significantly more fluids than patients who did not.

Conclusion

PP is associated with an increase in cardiac index in 18% to 32% of all PP sessions and a sustained increase in GEDVI reversible after return to supine position. Return from prone to supine position is associated with a slight hemodynamic impairment.

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0464-9) contains supplementary material, which is available to authorized users.

Effect of Bronchoscopy on Gas Exchange and Respiratory Mechanics in Critically Ill Patients With Atelectasis: An Observational Cohort Study

Background: Atelectasis frequently develops in critically ill patients and may result in impaired gas exchange among other complications. The long-term effects of bronchoscopy on gas exchange and the effects on respiratory mechanics are largely unknown.

Objective: To evaluate the effect of bronchoscopy on gas exchange and respiratory mechanics in intensive care unit (ICU) patients with atelectasis.

Methods: A retrospective, single-center cohort study of patients with clinical indication for bronchoscopy because of atelectasis diagnosed on chest X-ray (CXR).

Results: In total, 101 bronchoscopies were performed in 88 ICU patients. Bronchoscopy improved oxygenation (defined as an increase of PaO₂/FiO₂ ratio > 20 mmHg) and ventilation (defined as a decrease of > 2 mmHg in partial pressure of CO₂ in arterial blood) in 76 and 59% of procedures, respectively, for at least 24 h. Patients with a low baseline value of PaO₂/FiO₂ ratio and a high baseline value of PaCO₂ were most likely to benefit from bronchoscopy. In addition, in intubated and pressure control ventilated patients, respiratory mechanics improved after bronchoscopy for up to 24 h. Mild complications, and in particular desaturation between 80 and 90%, were reported in 13% of the patients.

Conclusions: In selected critically ill patients with atelectasis, bronchoscopy improves oxygenation, ventilation, and respiratory mechanics for at least 24 h.

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.

Prone position during ECMO is safe and improves oxygenation

PURPOSE

Combination of prone positioning (PrP) and extracorporeal membrane oxygenation (ECMO) might be beneficial in severe acute respiratory distress syndrome (ARDS), because both approaches are recommended. However, PrP during ECMO might be associated with complications such as dislocation of ECMO cannulae. We investigated complications and change of oxygenation effects of PrP during ECMO to identify "responders" and discuss our results considering different definitions of response in the literature.


METHODS

Retrospective analysis of complications, gas exchange, and invasiveness of mechanical ventilation during first and second PrP on ECMO at specified time points (before, during, and after PrP). We used multivariate nonparametric analysis of longitudinal data (MANOVA) to compare changes of mechanical ventilation and hemodynamics associated with the first and second procedures.


RESULTS

In 12 ECMO patients, 74 PrPs were performed (median ECMO duration: 10 days (IQR: 6.3-
15.5 days)). No dislocations of intravascular catheters/cannulae, endotracheal tubes or chest tubes were observed. Two PrPs had to be interrupted (endotracheal tube obstruction, acute pulmonary embolism). PaO2/FiO2-ratio increased associated with the first and second PrP (p = 0.002) and lasted after PrP in 58% of these turning procedures ("responders") without changes in ECMO blood flow, respiratory pressures, minute ventilation, portion of spontaneously triggered breathing, and compliance. Hemodynamics did not change with exception of increased mean pulmonary arterial pressure during PrP and decrease after PrP (p<0.001), while norepinephrine dosage decreased (p = 0.03) (MANOVA).


CONCLUSIONS

Prone position during ECMO is safe and improves oxygenation even after repositioning. This might ameliorate hypoxemia and reduce the harm from mechanical ventilation.

Body position changes redistribute lung computed-tomographic density in patients with acute respiratory failure: impact and clinical fallout through the following 20 years

In patients with acute respiratory distress syndrome (ARDS), in supine position, there is a decrease of inflation along the sternum vertebral axis, up to lung collapse. In 1991 we published a report showing that, in ARDS patients, shifting from supine to prone position led immediately to the inversion of the inflation gradient and to a redistribution of densities from dorsal to ventral lung regions. This led to a "sponge model" as a wet sponge, similar to a heavy edematous lung, squeezes out the gas in the most dependent regions, due to the weight-related increase of the compressive forces. The sponge model accounts for density distribution in prone position, for which the unloaded dorsal regions are recruited, while the loaded ventral region, collapses. In addition, the sponge model accounts for the mechanism through which the positive end-expiratory pressure acts as counterforce to oppose the collapsing, compressing forces. The final result of proning was that the inversion of gravitational forces, together with other factors such as lung-chest wall shape-matching and the heart weight led to a more homogeneous distribution of inflation throughout the lung parenchyma. This is associated with oxygenation improvement as the dorsal recruitment, for anatomical reasons, prevails on the ventral de-recruitment. The more homogeneous distribution of inflation (i.e. of stress and strain) decreases/prevents the ventilator-induced lung injury, as consistently shown in animal experiments. Finally, and a series of clinical trials led to the conclusion that in patients with severe ARDS, the prone position provides a significant survival advantage.

The effect of prone positioning in acute respiratory distress syndrome or acute lung injury: a meta-analysis. Areas of uncertainty and recommendations for research

OBJECTIVE

To compare the effects of ventilation in prone and in supine position in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS).

DESIGN

Meta-analysis of randomised controlled trials.

DATA SOURCES

BioMedCentral, PubMed, CINAHL, and Embase (to November 2007), with additional information from authors.

MEASUREMENTS AND RESULTS

From selected randomised controlled trials comparing positioning in ALI/ARDS we extracted data concerning study design, disease severity, clinical outcomes, and adverse events. Five trials including 1,372 patients met the inclusion criteria for mortality analysis; one trial was added to assess the effects on acquisition of ventilator-associated pneumonia (VAP). The included trials were significantly underpowered and enrolled patients with varying severity. Prone positioning duration and mechanical ventilation strategy were not standardised across studies. Using a fixed-effects model, we did not find a significant effect of prone positioning (proning) on mortality (odds ratio 0.97, 95% confidence interval 0.77-1.22). The PaO(2)/FiO(2) ratio increased significantly more with proning (weighted means difference 25 mmHg, p < 0.00001). Proning was associated with a non-significant 23% reduction in the odds of VAP (p=0.09), and with no increase in major adverse airway complications: OR 1.01, 95% CI 0.71-1.43. Length of intensive care unit stay was marginally and not significantly increased by proning.

CONCLUSIONS

Prone position is not associated with a significant reduction in mortality from ALI/ARDS despite a significant increase in PaO(2)/FiO(2), is safe, and tends to decrease VAP. Published studies exhibit substantial clinical heterogeneity, suggesting that an adequately sized study optimising the duration of proning and ventilation strategy is warranted to enable definitive conclusions to be drawn.

[The prone position in acute respiratory distress syndrome: a critical systematic review]

OBJECTIVE

To do a critical systematic review regarding effects of prone positioning (PP) in patients with acute respiratory distress syndrome (ARDS).

METHODS

A systematic review (Highwire, Medline, Cochrane Library from 1976 to 2004), using the keywords: prone position, acute respiratory distress syndrome, allowed us to include the human studies on PP in ARDS patients, independantly of their objectives or their type of protocol. To appreciate the studies validity, we scored the quality evidence of the studies in order to grade our conclusions.

RESULTS AND CONCLUSION

The qualitative analysis of the 58 included studies (1,500 patients returned prone, 4,000 episodes of PP) led to the following main conclusions: 1) the PP improves oxygenation in the majority of ARDS patients (level of evidence I); 2) the PP improves the pulmonary haemodynamics without altering the systemic haemodynamics (level of evidence III); 3) the PP enhances the recruitment maneuvers (level of evidence III); 4) because there are no formal predictive criteria for response to the PP, a "trial of PP" or better two PP trials are necessary to look for the responders; 5) the PP should be performed as early as possible in the course of severe ARDS; 6) the optimal duration of PP is 18 to 23 hours daily, and it should be continued until improvement of arterial oxygenation, or loss of the positive effect of PP on arterial oxygenation or evidently patient's death.

Alveolar recruitment during prone position: time matters

Alveolar recruitment is one of the beneficial effects of prone positioning in patients with ARDS (acute respiratory distress syndrome). However, responses vary among patients and, therefore, we hypothesized that alveolar recruitment is an individual time-dependent process and its measurement might be helpful to 'dose' prone positioning individually. In 13 patients diagnosed with ARDS, EELV (end-expiratory lung volume) was measured in the supine position, immediately after turning to the prone position, at 1, 2, 4 and 8 h in the prone position and after returning to the supine position. Responders were defined based on a 30% increase in oxygenation. EELV increased in responders, whereas it remained constant in non-responders. The time course was different in individual patients. In some responders, a plateau was reached as early as 2-4 h, whereas, in others, 8 h of prone positioning was not sufficient to allow complete recruitment. The increase in lung volume was associated with both an increase in arterial oxygenation and a decrease in venous admixture. Furthermore, responders had significantly lower baseline EELVs than non-responders. In conclusion, alveolar recruitment during prone positioning has been characterized as an individual time-dependent process. Its measurement might be useful to apply prone positioning more individually and might also help to identify responders.

Prone positioning improves oxygenation in post-traumatic lung injury--a prospective randomized trial

BACKGROUND

In a prospective randomized trial the effect of prone positioning on the duration of mechanical ventilation was evaluated in multiple trauma patients and was compared with patients ventilated in supine position.

METHOD

Multiple trauma patients of the intensive care units of two university hospitals were considered eligible if they met the criteria for acute lung injury or the acute respiratory distress syndrome. Patients in the prone group (N = 21) were kept prone for at least eight hours and a maximum of 23 hours per day. Prone positioning was continued until a PaO2:FiO2 ratio of more than 300 was present in prone as well as supine position over a period of 48 hours. Patients in the supine group (N = 19) were positioned according to standard care guidelines.

RESULTS

The duration of ventilatory support did not differ significantly (30 +/- 17 days in the prone group and 33 +/- 23 days in the supine group). Worst case analysis (death and deterioration of gas exchange) displayed ventilatory support for 41 +/- 29 days in the prone group and 61 +/- 35 days in the supine group (p = 0.06). The PaO2:FiO2 ratio increased significantly more in the prone group in the first four days (p = 0.03). The prevalence of Acute Respiratory Distress Syndrome (ARDS) following acute lung injury (p = 0.03) and the prevalence of pneumonia (p = 0.048) were reduced also. One patient in the prone and three patients in the supine group died due to multi organ failure (p = 0.27).

CONCLUSIONS

Intermittent prone positioning was not able to reduce the duration of mechanical ventilation in this limited number of patients. However the oxygenation improved significantly over the first four days of treatment, and the prevalence of ARDS and pneumonia were reduced.

Lung recruitment during mechanical positive pressure ventilation in the PICU: what can be learned from the literature?

A literature review was conducted to assess the evidence for recruitment manoeuvres used in conventional mechanical positive pressure ventilation. A total of 61 studies on recruitment manoeuvres were identified: 13 experimental, 31 ICU, 6 PICU and 12 anaesthesia studies. Recruitment appears to be a continuous process during inspiration and expiration and is determined by peak inspiratory pressure (PIP) and positive end expiratory pressure (PEEP). Single or repeated recruitment manoeuvres may result in a statistically significant increase in oxygenation; however, this is short lasting and clinically irrelevant, especially in late ARDS and pneumonia. Temporary PIP elevation may be effective but only after PEEP loss (for example disconnection and tracheal suctioning). Continuous PEEP elevation and prone positioning can increase P(a)O2 significantly. Adverse haemodynamic or barotrauma effects are reported in various studies. No data exist on the effect of recruitment manoeuvres on mortality, morbidity, length of stay or duration of mechanical ventilation. Although recruitment manoeuvres can improve oxygenation, they can potentially increase lung injury, which eventually determines outcome. Based on the presently available literature, prone position and sufficient PEEP as part of a lung protective ventilation strategy seem to be the safest and most effective recruitment manoeuvres. As paediatric physiology is essentially different from adult, paediatric studies are needed to determine the role of recruitment manoeuvres in the PICU.

High-frequency oscillatory ventilation in adults: respiratory therapy issues

OBJECTIVE

To summarize clinical information and assessment techniques relevant to respiratory therapists caring for adult patients on high-frequency oscillatory ventilation (HFOV).

DATA SOURCE

Review of observational studies, controlled trials, case reports, institutional experience, and hospital HFOV guidelines for adult patients.

DATA SUMMARY

Respiratory therapists require unique physical assessment skills and knowledge in managing patients on HFOV. Respiratory therapy procedures relevant to HFOV include setting endotracheal tube cuff leaks, performing lung recruiting maneuvers, endotracheal suctioning, and monitoring ventilator parameters. Respiratory therapists serve as essential team members in the creation and implementation of written HFOV guidelines (e.g., algorithms) to optimize patient care.

CONCLUSION

Respiratory therapy assessment and procedural skills are essential in providing optimal care to adult patients on HFOV.

Prone position delays the progression of ventilator-induced lung injury in rats: Does lung strain distribution play a role?*

OBJECTIVE

To investigate if prone position delays the progression of experimental ventilator-induced lung injury, possibly due to a more homogeneous distribution of strain within lung parenchyma.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Animal laboratory of a university hospital.

SUBJECTS

Thirty-five Sprague Dawley male rats (weight 257 +/- 45 g).

INTERVENTIONS

Mechanical ventilation in either supine or prone position and computed tomography scan analysis.

MEASUREMENTS

: Animals were ventilated in supine (n = 15) or prone (n = 15) position until a similar ventilator-induced lung injury was reached. To do so, experiments were interrupted when respiratory system elastance was 150% of baseline. Ventilator-induced lung injury was assessed as lung wet-to-dry ratio and histology. Time to reach lung injury was considered as a main outcome measure. In five additional animals, computed tomography scans (GE Light Speed QX/I, thickness 1.25 mm, interval 0.6 mm, 100 MA, 100 Kv) were randomly taken at end-expiration and end-inspiration in both positions, and quantitative analysis was performed. Data are shown as mean +/- sd.

MEASUREMENTS AND MAIN RESULTS

Similar ventilator-induced lung injury was reached (respiratory system elastance, wet-to-dry ratio, and histology). The time taken to achieve the target ventilator-induced lung injury was longer with prone position (73 +/- 37 mins vs. 112 +/- 42, supine vs. prone, p = .011). Computed tomography scan analysis performed before lung injury revealed that at end-expiration, the lung was wider in prone position (p = .004) and somewhat shorter (p = .09), despite similar lung volumes (p = .455). Lung density along the vertical axis increased significantly only in supine position (p = .002). Lung strain was greater in supine as opposed to prone position (width strain, 7.8 +/- 1.8% vs. 5.6 +/- 0.9, supine vs. prone, p = .029).

CONCLUSIONS

Prone position delays the progression of ventilator-induced lung injury. Computed tomography scan analysis suggests that a more homogeneous distribution of strain may be implicated in the protective role of prone position against ventilator-induced lung injury.

Recruitment maneuvers during prone positioning in patients with acute respiratory distress syndrome

OBJECTIVE

To evaluate the interaction of recruitment maneuvers and prone positioning on gas exchange and venous admixture in patients with early extrapulmonary acute respiratory distress syndrome ventilated with high levels of positive end-expiratory pressure. We hypothesized that a sustained inflation performed after 6 hrs of prone positioning would induce sustained improvement in oxygenation (Pao2/Fio2) and venous admixture.

DESIGN

Prospective, interventional study.

SETTING

Tertiary care, postoperative intensive care unit.

PATIENTS

Fifteen patients with early extrapulmonary acute respiratory distress syndrome.

INTERVENTIONS

After 6 hrs of prone positioning, a sustained inflation was performed with 50 cm H2O maintained for 30 secs. Data were recorded in supine position, after 6 hrs of prone positioning, at 3, 30, and 180 mins following the sustained inflation.

MEASUREMENTS AND MAIN RESULTS

A response to prone positioning was observed in nine of 15 patients leading to an improvement of Pao2/Fio2 (147 +/- 37 torr vs. 225 +/- 77 torr, p = .005) and venous admixture (35.4 +/- 8.3% vs. 28.9 +/- 9.8%, p = .001). Six patients did not respond to prone positioning. Following the sustained inflation, the responders to prone positioning showed a further increase of Pao2/Fio2 and decrease of venous admixture at 3 mins (Pao2/Fio2, 225 +/- 77 torr vs. 368 +/- 90 torr, p = .018; venous admixture, 28.9 +/- 9.8% vs. 18.9 +/- 6.7%, p = .05). In all six nonresponders to prone positioning, an improvement of Pao2/Fio2 and venous admixture occurred at 3 mins following the sustained inflation (128 +/- 18 torr vs. 277 +/- 59 torr, p = .03; venous admixture, 34.2 +/- 6.0% vs. 23.8 +/- 6.3%, p = .05). The beneficial effects of the sustained inflation remained significantly elevated over 3 hrs in responders and nonresponders to prone positioning.

CONCLUSION

In patients with early extrapulmonary acute respiratory distress syndrome, a sustained inflation performed after 6 hrs of prone positioning induced further and sustained improvement of oxygenation and venous admixture in both responders and nonresponders to prone positioning.

Prone positioning in the patient who has acute respiratory distress syndrome: the art and science

Acute respiratory distress syndrome (ARDS) remains a significant contributor to the morbidity and mortality of patients in the ICU. A variety of treatments are used to support the lung of the patient who has ARDS and improve gas exchange during the acute injury phase. It seems, however, that the simple, safe, and noninvasive act of prone positioning of the critically ill patient who has ARDS may improve gas exchange while preventing potential complications of high positive end-expiratory pressure, volutrauma, and oxygen toxicity. This article provides the critical care nurse with the physiologic rationale for use of the prone position, indications and contraindications for use, safe strategies for prone positioning, and care techniques and monitoring methods of the patient who is in the prone position.

Approaches in the management of acute respiratory failure in children

PURPOSE OF REVIEW

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are conditions that are associated with significant morbidity and mortality in children. There have been no advances in preventing ARDS, but this review highlights strategies directed at minimizing ventilator-induced lung injury and other new adjunctive therapies in the care of these patients.

RECENT FINDINGS

High-frequency oscillatory ventilation, airway pressure release ventilation, and partial liquid ventilation are potential protective ventilatory modes for children with ALI or ARDS. Recruitment maneuvers, prone positioning, and kinetic therapy are all reported to improve oxygenation by opening the lung while positive end-expiratory pressure maintains functional residual capacity. Inhaled nitric oxide and surfactant are used to reduce inspired oxygen concentration and facilitate gas exchange, but their efficacy in ARDS continues to be investigated. Also, early investigations suggest that a specialized enteral formula can be a useful adjunctive therapy by reducing lung inflammation and improving oxygenation. When mechanical ventilation and adjunctive therapies fail, extracorporeal life support continues to be used as a rescue therapy.

SUMMARY

It is likely that a combination of these therapies will maximize treatment and clinical outcomes in the future, but the only way that will be proven is through large controlled clinical trials in pediatric patients.

Septic shock, multiple organ failure, and acute respiratory distress syndrome

In 1914, Schottmueller wrote "Septicemia is a state of microbial invasion from a portal of entry into the blood stream which causes signs of illness." In the last few decades, the evidence that sepsis results from an exaggerated systemic inflammatory host response induced by infecting organisms is compelling; inflammatory mediators are the key players in the pathogenesis of septic shock and multiorgan failure. Sepsis and its sequelae represent a continuum of clinical syndrome encompassing systemic inflammation, coagulopathy, and hemodynamic abnormalities. Severe sepsis and septic shock continue to be the major causes of morbidity and mortality in the United States; sepsis deaths currently match mortality from myocardial infarction. Despite significant advances in our understanding of the pathophysiology and technological innovations in the supportive management, mortality from septic shock remains excessive. After many disappointments with strategies to manipulate the inflammatory response, modulation of coagulation cascade to decrease sepsis mortality has become a clinical reality. This review will highlight and discuss recent advances in the pathophysiology and management of sepsis.

Tratamientos complementarios: óxido nítrico, posición en prono y surfactante

The management of hypoxic respiratory failure is based on oxygen delivery and ventilatory support with lung-protective ventilation strategies. Better understanding of acute lung injury have led to new therapeutic approaches that can modify the outcome of these patients. These adjunctive oxygenation strategies include inhaled nitric oxide and surfactant delivery, and the use of prone positioning. Nitric oxide is a selective pulmonary vasodilator that when inhaled, improves oxygenation in clinical situations such as persistent pulmonary hypertension of the newborn, pulmonary hypertension associated with congenital heart disease, and acute respiratory distress syndrome (ARDS). When applied early in ARDS, prone positioning improves distribution of ventilation and reduces the intrapulmonary shunt. The surfactant has dramatically decreased mortality caused by hyaline membrane disease in premature newborns, although the results have been less successful in ARDS. Greater experience is required to determine whether the combination of these treatments will improve the prognosis of these patients.