Lungs in good health obtain the best match when the body is standing upright

The next best position is sitting straight upright.

(Bryant et al 1965; West 1985)

The upright position is essential to maximize lung volume, flow rates, and VQ matching in gas exchange. This position is the only means of optimizing fluid shifts such that circulating blood volume and volume regulating mechanisms are maintained.

The Importance of Positioning

If there is an imbalance in distribution perfusion, you

have a VQ mismatch

VQ matching is influenced by body position, gravity and

lung injury

I Schematic of gas exchange at the alveolar AV interface

What can we do for the critically ill patient?

Conventional treatment is to turn side to side but

what can we do when they are too

hemodynamically unstable to tolerate turning?

Leaving them supine is not the answer.

In the stationary supine position, 17% of the lung rests beneath the compressing forces of the heart. This results in a more positive pleural pressure resulting in alveolar collapse.

Gray area is the lung lower lobe tissue compressed by the heart

White area is the lung lower lobe tissue not compressed by the heart

Schematic representation of a CT scan obtained in the supine position.( Malbouisson, 2000)

If the heart is enlarged, up to 37% of the lungs might be affected by these forces. ( Malbouisson, 2000)

Abdominal contents exert a

significant amount of pressure on

the diaphragm when the patient is

supine, sedated, ventilated and

mechanically ventilated.

Xray of abdominal distention

Effect of Abdominal Contents on the Ventilated Patient

In the healthy person in the

supine position, the diaphragm

acts as a barrier to the pressure

exerted by abdominal

contents, preventing interference

with air distribution in the

dependent segments of the lung.

This adversely affects FRC and

contributes to shunt. The larger the

abdomen, the greater negative

effect on ventilation.

( Froese & Bryant 1974)

Gas exchange occurs in the AV capillary membrane by diffusion. Four factors maintain the physiological balance:

1. Capillary hydrostatic

pressure-mechanical force

of fluid pushing against

the cellular membranes.

2. Capillary oncotic

pressure-Osmotic effect

that holds fluid in the

capillary.

3. Capillary permeability.

4. Surfactant lining the

alveoli which repels water

preventing fluid from

entering the alveoli.

(Kubo, A. 2008)

The Primary Function of the Lung is Gas Exchange

Pathophysiology of Acute Lung Injury

Diffuse non-uniform structural damage to the AC membrane causes

severe pulmonary edema, shunting and hypoxemia. A massive

inflammatory response is caused by chemical mediators. In ALI and

ARDs, this response is amplifiedThe AC membrane becomes

permeable resulting in an influx of

fluid, proteins and blood cells from

the capillary bed into the

alveoli, resulting in pulmonary

edema.

These chemical mediators also

damage the alveolar endothelium

where surfactant is produced.

Without surfactant, the alveoli

collapse causing atelectasis The

lungs lose compliance and

ventilation decreases due to

atelectasis. The resulting right to

left shunt results in unoxygenated

blood returning to the left

heart, worsening hypoxemia.

( Kubo, 2008)

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<235

S/F ratios are a reasonable correlate to identify early ALI and ARDs

(Rice et al, 2009)

It’s easier to prevent atelectasis and maintain functional residual capacity than to try to restore alveolar patency. CLRT continuously moves one lung over the other, causing extravasation of lung water, mobilizing secretions and decreasing the risk of alveolar collapse. The movement from side to side maintains a higher FRC in the mechanically ventilated patient and so CLRT is able to influence the amount of pressure necessary to open collapsed alveoli.(Kubo, 2008)

CLRT rotation puts the “good” lung in a dependent position to optimize gas exchange and improve oxygenation.

When the “bad” lung is down, there is a slow but steady recruitment of collapsed alveoli as secretions begin to mobilize, occurring as rotation moves the body in a slow steady arc .

Published practice guidelines recommend rotating at an 80 to 100% arc (This translates to 35-40 degrees to each side) at a setting of 8 to 10 rotations an hour, for a total of 18 hours out of 24 for the full benefit, These recommendations are based on several research studies.(Vollman, 2004)

Principals of CLRT

Unstable spinal cord injury

Increased intracranial pressure

Long bone fractures with traction

Draining ventriculostomy

Possibly CVVHD (depending on access)

Open abdominal wound

Palliative care

FIO2 > 0.50

PEEP > 8

P/F Ratio S/F Ratio

ALI < 300 ALI <315

ARDS <200 ARDS <235

Lobar collapse, atelectasis, excessive secretions

Hemodynamic instability with manual turning

Decreased mental status

Increased sedation or paralytics needed to ventilate

Progressing to maximum ventilatory support

Requiring the use of nitric or epoprostenol

Oscillator vent

CLRT to Upright Mobility Protocol

Initiate within 24 hours of intubation. Assess vital signs, ECG, and SPO2 for 2 complete rotations and for every change in rotation after a 5 minute equilibrium period.

Rotate at 80-100%, 10-12 cycles per hour for a target of 18 hours per day.

Adjust by increasing the pause times before decreasing the 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 and offload pressure areas with pillows. Return to rotation when redness subsides. Don’t rotate with pillows propped beneath back.

Check ABGs with the patient stopped at center.

Documentation

Percent of rotationHours rotated per dayPulmonary assessmentABGsP/F ratio or S/F ratioChest Xray results

Change in B/P or other hemodynamic parameters: Assess filling pressures ( CVP, PP variation) to determine if a fluid bolus is needed.

Assess vasodilatory problems: sepsis, neurogenic shock pattern, low diastolic pressure and/or SVR, SVRi ( if available) for adequacy of pressor support.

Assess adequacy of inotropic support ( HR, CO if available, 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)

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.

Changes in SpO2

Remember: With rotation, shunt should decrease and saturation levels should improve.

( Washington, 2005)

Improves vital capacity and functional residual capacity. Increases spontaneous tidal volumes, and decreases the pressure on the diaphragm exerted by abdominal contents.

Reconditions impaired baroreceptor responses to changes in volume status, decreasing orthostatic stress.

Raise the head of the bed 45 degrees twice a day at 9AM and 9PM. Correlate it with the morning wake up and evening assessment.

Remember to decrease the sedation if tolerated after morning wake-ups. Maintain a Riker score of 3 to 4.

Decreasing sedation will improve mobility outcomes.

Improved Chest Xray

Improved ABGs

Improvement in P/F Ratio or S/F Ratio

Patient able to move and turn self

Sedatives decreased

At this point, the patient is ready to advance to 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 of VAP, shorten ventilator days and decrease both ICU and hospital lengths of stay.

CLRT is a therapy that allows recruitment of collapsed alveoli and improves oxygenation by mobilizing secretions and decreasing VQ mismatch.

MICU has 24 CLRT beds . A situation unmatched by any ICU in the area.

So lets get our patients rotating! One good turn deserves another!

Ahrens, T, Kollef, M, Stewart, J, Shannon, W.

Effect of kinetic therapy on pulmonary complications. Am. Journal of Critical Care. (2004) 13:376-383

Bryan, 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) 19:395-402

Froese, A, Bryan, AC. Effects of anesthesia and paralytics on diaphragmatic mechanics in man. Anesthesiology (1974) 41: 242-55

Kubo, A. Progressive Mobility in the ICU: Self Directed Study, University of Kansas

Hospital, 2008

Malbouisson, 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) 161-2005-12

Rice, 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) 132:410-17

Vollman, K. The right position at the right time; mobility makes a difference

Intensive and Critical Care Nursing (2004) 20: 179-82

Washington, G, Macnee, C. Evaluation of outcomes: the effects of continuous lateral rotation therapy. Journal of Nursing Care Quality (2005) 20(3): 273-282