The Importance of Positioning The upright position is essential to maximize lung volume, flow rates, and VQ matching in gasexchange. This position is the only means of optimizing fluid shifts such that circulating bloodvolume and volume regulating mechanisms are maintained. Lungs in good health The next best position is obtain the best match sitting straight upright. when the body is standing (Bryant et al 1965; West 1985) upright
I Schematic of gas exchange at the alveolar AV interface If there is an imbalance in distribution perfusion, you have a VQ mismatch VQ matching is influenced by body position, gravity and lung injury
What can we do for the critically ill patient?Conventional treatment is to turn side to side butwhat can we do when they are toohemodynamically unstable to tolerate turning?Leaving them supine is not the answer.
In the stationary supine position, 17% of the lung rests beneaththe compressing forces of the heart. This results in a morepositive pleural pressure resulting in alveolar collapse. Schematic representation of a CT scan obtained in the supine position. ( Malbouisson, 2000) White area is the lung lower lobe Gray area is the lung lower tissue not compressed by the heart lobe tissue compressed by the heart If the heart is enlarged, up to 37% of the lungs might be affected by these forces. ( Malbouisson, 2000)
Effect of Abdominal Contents on the Ventilated Patient In the healthy person in thesupine position, the diaphragmacts as a barrier to the pressureexerted by abdominalcontents, preventing interferencewith air distribution in thedependent segments of the lung. Abdominal contents exert asignificant amount of pressure onthe diaphragm when the patient issupine, sedated, ventilated andmechanically ventilated. This adversely affects FRC andcontributes to shunt. The larger theabdomen, the greater negativeeffect on ventilation. ( Froese & Bryant 1974) Xray of abdominal distention
The Primary Function of the Lung is Gas Exchange Gas exchange occurs inthe AV capillarymembrane by diffusion.Four factors maintain thephysiological balance: 1. Capillary hydrostaticpressure-mechanical forceof fluid pushing againstthe cellular membranes. 2. Capillary oncoticpressure-Osmotic effectthat holds fluid in thecapillary. 3. Capillary permeability. 4. Surfactant lining thealveoli which repels waterpreventing fluid from entering the alveoli. (Kubo, A. 2008)
Pathophysiology of Acute Lung Injury Diffuse non-uniform structural damage to the AC membrane causessevere pulmonary edema, shunting and hypoxemia. A massiveinflammatory response is caused by chemical mediators. In ALI andARDs, this response is amplifiedThe AC membrane becomespermeable resulting in an influx offluid, proteins and blood cells fromthe capillary bed into thealveoli, resulting in pulmonaryedema.These chemical mediators alsodamage the alveolar endotheliumwhere surfactant is produced.Without surfactant, the alveolicollapse causing atelectasis Thelungs lose compliance andventilation decreases due toatelectasis. The resulting right toleft shunt results in unoxygenatedblood returning to the leftheart, worsening hypoxemia.
The P/F ratio is a measure of intrapulmonary shunting, and is obtained by comparing arterial to inspired oxygen. This value can be calculated by dividing the arterial oxygen tension ( PO2) by the fraction of inspired oxygen (FIO2) Example: PO2 90/ FIO2 .40= 225 (Oh Oh! ) Don’t forget the decimal in the FIO2 when doing the calculation. The values for ALI and ARDs are as follows: Acute lung injury P/F<300 Acute respiratory distress P/F<200
The S/F ratio is a correlation to the P/F ratio and is calculated using the O2 Sat instead of the PO2.EPIC calculates and records the S/F ratio .The values are a little different: Acute lung injury S/F Ratio <315 Acute Respiratory Distress S/F Ratio<235S/F ratios are a reasonable correlate to identify early ALI and ARDs (Rice et al, 2009)
Principals of CLRT It’s easier to prevent atelectasis and maintain functional residual capacity than to try torestore alveolar patency. CLRT continuously moves one lung over the other, causingextravasation of lung water, mobilizing secretions and decreasing the risk of alveolarcollapse. The movement from side to side maintains a higher FRC in the mechanicallyventilated patient and so CLRT is able to influence the amount of pressure necessary toopen collapsed alveoli.(Kubo, 2008) CLRT rotation puts the “good” lung in adependent position to optimize gas exchangeand improve oxygenation. When the “bad” lung is down, there is a slowbut steady recruitment of collapsed alveoli assecretions begin to mobilize, occurring asrotation moves the body in a slow steady arc . Published practice guidelines recommendrotating at an 80 to 100% arc (This translatesto 35-40 degrees to each side) at a setting of 8to 10 rotations an hour, for a total of 18 hoursout of 24 for the full benefit, Theserecommendations are based on severalresearch studies. (Vollman, 2004)
Unstable spinal cord injuryIncreased intracranial pressureLong bone fractures with tractionDraining ventriculostomy Possibly CVVHD (depending on access)Open abdominal woundPalliative care
FIO2 > 0.50PEEP > 8P/F Ratio S/F Ratio ALI < 300 ALI <315 ARDS <200 ARDS <235Lobar collapse, atelectasis, excessive secretionsHemodynamic instability with manual turningDecreased mental statusIncreased sedation or paralytics needed to ventilateProgressing to maximum ventilatory supportRequiring the use of nitric or epoprostenolOscillator vent
Initiate within 24 hours of intubation. Assess vitalsigns, ECG, and SPO2 for 2 complete rotations and forevery change in rotation after a 5 minute equilibriumperiod.Rotate at 80-100%, 10-12 cycles per hour for a targetof 18 hours per day.Adjust by increasing the pause times before decreasingthe rotation angle.Increase rotation angle by using the training mode.This increases rotation by 10% every hour.Insure that sedation is adequate.
Stop rotation and assess the skin every 4 hours andoffload pressure areas with pillows. Return to rotationwhen redness subsides. Don’t rotate with pillowspropped beneath back.Check ABGs with the patient stopped at center. Documentation Percent of rotation Hours rotated per day Pulmonary assessment ABGs P/F ratio or S/F ratio Chest Xray results
Change in B/P or other hemodynamic parameters:Assess filling pressures ( CVP, PP variation) todetermine if a fluid bolus is needed.Assess vasodilatory problems: sepsis, neurogenic shockpattern, low diastolic pressure and/or SVR, SVRi ( ifavailable) for adequacy of pressor support.Assess adequacy of inotropic support ( HR, CO ifavailable, mixed venous sat) Remember: Changes in hemodynamics during rotation are due to alterations in the determinants of cardiac output and NOT due to the rotation ( Washington & MacNee, 2005)
Changes in SpO2 Adjust pause times so that the pause is shortened on the side where the desaturation occurs. Suction more frequently. Rotation mobilizes secretions. Make certain the pleth reading is accurate. Assess the level of desaturation when the bad lung is down. Consult with a physician to determine what level of desaturation is acceptable.Remember: With rotation, shunt should decrease andsaturation levels should improve. ( Washington, 2005)
Improves vital capacity and functional residualcapacity. Increases spontaneous tidal volumes, anddecreases the pressure on the diaphragm exerted byabdominal contents.Reconditions impaired baroreceptor responses tochanges in volume status, decreasing orthostaticstress.Raise the head of the bed 45 degrees twice a day at9AM and 9PM. Correlate it with the morning wake upand evening assessment.Remember to decrease the sedation if tolerated aftermorning wake-ups. Maintain a Riker score of 3 to 4.Decreasing sedation will improve mobility outcomes.
Improved Chest XrayImproved ABGsImprovement in P/F Ratio or S/F RatioPatient able to move and turn selfSedatives decreasedAt this point, the patient is ready to advanceto progressive upright mobility
Anzueto et al, Critical Care Medicine;199712 healthy baboons were randomized to CLRT or control for 11 days. Mechanically ventilated, sedated and paralyzed with supportive care. Studies done were xrays, cultures, BAL samples, oxygenation indices, pulmonary function and lung volumes.Results: Day 7 the control group showed patchy atelectasis; day 11 2two animals showedpersistent Xray abnormalities;BAL on days 7&11 showed large WBC increases;Lung pathology showed bronchiolitiswith 5 of the 7 subjects developing bronchopneumonia.Ahrens et al, AJCC 2004Multicenter study that included 255 patients with a PF ratio < 250, GCS <11 and mechanically ventilated.Results: VAP and atelectasis were markedly reduced in CLRT patients within 5 days and the PF ratio had improved within 2 days.Kirschenbaum et al, Critical Care Medicine (2002)37 vent dependent MICU patients, randomized to CLRT and control.Results: 17.6% of CLRT group developed pneumonia compared with 50% of the control group,
Choi& Nelson, Journal of Critical care (1992)Meta-analysis of 6 studies involving 419 patients.Results: Significant reduction in incidence of pneumonia and atelectasis with CLRT. Significant reduction in ventilator time and LOS in ICU with CLRT.Goldhill, AJCC (2007)Meta-analysis of 35 studies between 1987-2004. Found that rotational therapy decreased the incidence of pneumonia but had no effect on duration of mechanical ventilation, LOS in ICU or hospital mortality. Conclusion: Rotational therapy is useful in preventing and treating respiratory complications but inconclusive on which rotation parameters are most effective. The author notes that rotational parameters and time of rotation were inconsistent from study to study, or not reported.Raoof et al, Chest ( 1999) 24 MICU patients with atelectasis were assigned to either rotation or manual turning every 2 hours.Results: 82.3% of the rotation group had resolution of atelectasis vs 14.3% of the control group with manual turning.
Feegler et al, Research Dimension (2009)Prospective trial with patients meeting CLRT criteria started on rotation within 24 hours of intubation. Control segment looked at retrospective patients who had met the criteria in the previous year.Results: The first phase of the study looked at early initiation of CLRT and found that ventilator days were decreased by 2.2 days and average hospital LOS was decreased by 3.6 days in the CLRT group when compared to the control group. The second phase looked at delayed placement on CLRT (within 5 days of ventilation) and found that early placement on CLRT significantly reduced ventilator days, ICU LOS and hospital LOS in the 2 CLRT groups.Staudinger et al, Critical Care medicine (2010)Prospective randomized clinical study. 150 ventilated patients were randomized to CLRT or standard care if ventilated < 48 hours and free of pneumonia.Results: CLRT patients had reduction in ventilator time ( 8 days VS 14) decreased LOS (25 days vs 45 days) and decreased rated of VAP, though not statistically significant—12 in the rotation group vs 23 in the control group (p=.08)
CLRT has been shown to decrease rates ofVAP, shorten ventilator days and decrease bothICU and hospital lengths of stay.CLRT is a therapy that allows recruitment ofcollapsed alveoli and improves oxygenation bymobilizing secretions and decreasing VQmismatch.MICU has 24 CLRT beds . A situation unmatchedby any ICU in the area.So lets get our patients rotating! One good turndeserves another!
Ahrens, T, Kollef, M, Stewart, J, Shannon, W.Effect of kinetic therapy on pulmonary complications. Am. Journal of Critical Care. (2004) 13:376-383Bryan, AG, Bentivoglio, LG, Beerel, F, MacLeish, M, Zidulkia, A, Bates, DV.Factors affecting regional distribution of ventilation and perfusion in the lung. Journal Applied Physiology (1964) 19:395-402Froese, A, Bryan, AC. Effects of anesthesia and paralytics on diaphragmatic mechanics in man. Anesthesiology (1974) 41: 242-55Kubo, A. Progressive Mobility in the ICU: Self Directed Study, University of Kansas Hospital, 2008Malbouisson, LM, Busch, CJ, Puybassert, L, Cluzel, P, Rouby, JJ.Role of the heart in the loss of aeration characterizing lower lobes in acute respiratory distress syndrome. American Journal of respiratory Critical care (2000) 161-2005-12Rice, T, Wheeler, A, Bernard, G, Hayden, D, Schoenfeld, D, Ware, L.Comparison of the Spo2/Fio2 ratio and the Pao2/Fio2 ratio in patients with acute lung injury or ARDS. Chest (2007) 132:410-17Vollman, K. The right position at the right time; mobility makes a difference Intensive and Critical Care Nursing (2004) 20: 179-82Washington, G, Macnee, C. Evaluation of outcomes: the effects of continuous lateral rotation therapy. Journal of Nursing Care Quality (2005) 20(3): 273-282