Effect of positioning on SvO2 in the critically ill patient with a low ejection fraction

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.

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.

Understanding critically ill patients hemodynamic response to mobilization: using the evidence to make it safe and feasible

In today's critical care environment, we face a difficult but essential task. We must provide comprehensive, compassionate, complex, technological care without causing harm to our patients. To foster a patient-safe environment, we must examine care practices and processes to reduce the chance of error. Successful early mobilization of critically ill patients can reduce several complications including atelectasis and ventilator-associated pneumonia and shorten ventilator time along with cognitive and functional limitations that linger 1 to 5 years after discharge from the intensive care unit. A long-standing challenge to successful mobilization of critically ill patients is the safety concern of hemodynamic instability. An in-depth exploration of what happens to a critically ill patient physiology during mobilization was done to foster a better understanding of strategies that promote adaptation. The article examines the evidence supporting the need to assess readiness for mobilization to reduce the risk of adverse events. Evidence-based tools and techniques to help clinicians prevent hemodynamic instability before, during, and after in-bed or out-of-bed mobilization are discussed. With safety serving as the overriding goal, we can overcome the barriers and succeed in creating and sustaining a culture of early progressive mobility programs within the intensive care unit.

The study of activity in older ICU patients: an integrative review

The purpose of this study was to review relevant literature on activity of older critically ill patients, including activity interventions conducted in this population, with a focus on activity measurement and technology. Literature published between 1996 and 2012 was reviewed using keywords older adults, inactivity, mobility, progressive mobility, rehabilitation, ambulation, early mobilization, ICU (intensive care unit), and accelerometry using CINAHL, MEDLINE, and the Cochrane Database of Systematic Reviews. Previous relevant research is discussed and includes intervention and nonintervention studies. Although studies have demonstrated the benefits of early mobilization in the ICU setting, this research has not focused on the high-risk older adult ICU population, nor has it addressed how best to quantify these clinical activities. Current technologies, such as accelerometry, may assist in measuring patient activity and in mobilizing high-risk patients during acute, critical illness.

Cardiovascular impact of manual and automated turns in ICU

Mechanically ventilated patients in the intensive care unit (ICU) are typically turned manually by nursing staff to reduce the risk of developing ventilator associated pneumonia and other problems in the lungs. However, turning can induce changes in the heart rate and blood pressure that can at times have a destabilizing effect. We report here on the early stage of a study that has been undertaken to measure the cardiovascular impact of manual turning, and compare it to changes induced when patients lie on automated beds that turn continuously. Heart rate and blood pressure data were analyzed over ensembles of turns with autoregressive models for comparing baseline level to the dynamic response. Manual turning stimulated a response in the heart rate that lasted for a median of 20 minutes and was of magnitude 5 to 13 bpm. The corresponding response in mean arterial pressure was 11 to 19 mm Hg, lasting for 8 to 21 minutes. There was no discernible response of either variable to automated turns.

Adverse hemodynamic effects of lateral rotation during mechanical ventilation

Turning critically ill, mechanically ventilated patients every 2 hours is a fundamental nursing intervention to reduce the negative impact of prolonged immobility from preventable pulmonary complications such as ventilator-associated pneumonia and atelectasis. Unfortunately, when coupled with positive pressure ventilation, the benefits of turning may come at the expense of cardiovascular function. Clinicians should closely monitor the hemodynamic response to turning mechanically ventilated patients, and if compromise is observed, the degree and duration of compromise may provide guidance to the appropriate intervention.

Lateral positioning of ventilated intensive care patients: a study of oxygenation, respiratory mechanics, hemodynamics, and adverse events

OBJECTIVES

To investigate the effect of 90 degrees lateral positioning on oxygenation, respiratory mechanics, and hemodynamics in ventilated intensive care patients.

METHODS

Thirty-four subjects (mean age = 46.1 +/- 17.3 years) with no, unilateral, or bilateral pulmonary infiltrates on chest radiograph participated. Arterial blood gas, respiratory mechanic, and hemodynamic data were analyzed at the supine starting position (T0), then 30 minutes and 2 hours into the lateral turn (T30 and T120, respectively) and 30 minutes post return to the supine position (T150).

RESULTS

No difference was found in PaO(2)/FiO(2) due to positioning patients from supine to lateral (P = .15) regardless of the underlying lung pathology. Dynamic compliance decreased during lateral positioning, particularly in the subjects with no lung pathology (T0 = 56 +/- 18.6 > (T30 = 49.9 +/- 18; T120 = 49.2 +/- 17) L/cmH(2)0, P < .01) or unilateral lung pathology (T0 = 41.4 +/- 11.2 > (T30 = 36.6 +/- 8.8; T120 = 37.3 +/- 9.5) L/cmH(2)0, P < .01). Blood pressure and heart rate were unaffected, but cardiac index significantly increased at T30 (T0 = 3.7 +/- 1.2, T30 = 4.8 +/- 1.3 L/min/m(2), P < .01). While the incidence of adverse events was high (21%), they were primarily minor and transient.

CONCLUSIONS

In this heterogeneous population, lateral positioning had no beneficial effect on gas exchange. However, in ventilated patients who were hemodynamically stable, it was well tolerated and not associated with significant serious adverse events.

Early postoperative 30° lateral positioning after coronary artery surgery: influence on cardiac output

AIMS AND OBJECTIVES

We investigated whether: (i) Early postoperative lateral position after coronary artery bypass surgery may have a negative influence on the cardiac output and (ii) Whether turning procedures cause practical problems.

BACKGROUND

Directly following surgery, coronary artery bypass patients are not receiving routine turning every two hours to prevent pressure ulcers, because a negative influence on hemodynamic parameters is assumed.

DESIGN

Clinical trial.

METHODS

Fifty-five coronary artery bypass patients were randomly assigned to four intervention regimens and underwent a two-hour period of 30 degrees lateral position. Fourteen patients in supine position served as a reference group. We hypothesized that 30 degrees lateral position does not cause a relevant change in the cardiac output.

RESULTS

Turning the patients did not have any significant influence on the cardiac index, not even in the patients in a poor hemodynamic condition. The cardiac index in 30 degrees lateral position and supine position two to eight hours postoperatively after coronary artery bypass surgery is statistically bioequivalent. No clinically relevant deviations from preset 'safe' values for mean arterial pressure, right atrial pressure, pulmonary artery wedge pressure and pulmonary arterial pressure were observed, which would require ending the lateral position. There were no practical problems hindering the turning regimen, not even in the patients with an intra-aortic balloon pump.

CONCLUSIONS

Early postoperative turning of coronary artery bypass surgery patients in lateral position is an easy and feasible procedure that does not influence the cardiac index not even in patients receiving antihypertensive or inotropic/vasopressor therapy. Further research is needed to find out whether our findings are also valid in other patient groups and other position conditions.

RELEVANCE TO CLINICAL PRACTICE

If there are no strict contra-indications, lateral position has to be considered to prevent complications of continuous supine position within two hours after coronary artery bypass surgery patients have been admitted to the intensive care unit.

Effect of lateral positions on tissue oxygenation in the critically ill

OBJECTIVE

The purpose of this study was to assess the effect of lateral positions on tissue oxygenation in critically ill patients.

DESIGN

The study design was prospective and quasi-experimental, and we used a convenience sample with random assignment.

SETTING

The study took place in the intensive care unit and the cardiac intensive care unit of a 450-bed medical center in the northwestern United States.

PATIENTS

The sample included 12 adult patients with indwelling pulmonary artery and radial arterial catheters who were receiving mechanical ventilation and who met the criteria of "critical illness" by having impaired arterial oxygenation (PaO2 < or = 70 mm Hg) and/or cardiac index < or = 2.0 L/min/m2.

OUTCOME MEASURES

The outcome measures were dependent variables reflecting oxygen delivery including heart rate, cardiac output, arterial oxygen content (CaO2) and oxygen consumption, and the adequacy of tissue oxygenation (serum lactate).

INTERVENTION

Each patient was passively turned to each of the three positions (right and left 45 degrees lateral and supine) according to a computer-generated, randomized positioning sequence. Dependent variables were measured 15 minutes after each position change. No changes in ventilator settings or vasoactive drugs occurred during data collection.

RESULTS

Analysis of variance for repeated measures was used in the data analysis. Post hoc analysis determined an effect size of 0.558 and power of 0.80 at an alpha level of.05. No statistically significant differences caused by position were found in mean CaO2, cardiac output, heart rate, respiratory rate, PaO2, SaO2, or lactate level. Pearson correlation analysis found no significant relationships between the primary variables reflecting oxygen delivery (cardiac output and CaO2) and serum lactate levels.

CONCLUSIONS

These findings suggest that lateral positioning of critically ill patients who are hypoxemic or have low cardiac output does not further endanger tissue oxygenation. Evaluation of individual patient responses to position changes in the clinical setting is encouraged until further studies using more heterogenous populations can provide more definitive guidance.