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Early progressive mobilization and physical therapy management in a patient with a total artificial heart device.

INTRODUCTION

Since its creation, over 950 patients have been implanted with SynCardia (formally known as CardioWest) Total Artificial Hearts (TAH). (1) The SynCardia TAH (SynCardia Systems, Inc. Tucson, AZ) has been shown to increase a patient's survival to heart transplant as well as survival following transplant (2) and was deemed an effective bridge-to-transplant device. (3-5) The TAH is a biventricular, pneumatic, pulsatile pump. Both native heart ventricles and all 4 valves are removed. The drivelines exit the patient's abdomen and connect to an external console.6

Research has shown that early mobility is safe (7), (8) and effective in decreasing both intensive care unit (ICU) and hospital length of stay, (8) as well as decreasing time needed to meet mobility milestones. (7) Physical therapists (PTs) are involved in early mobilization of these patients and recent research shows that PTs mobilize them to higher levels than do nurses. (9) As the volume of literature published regarding early mobility continues to grow, there is increasing information available to help guide PTs regarding protocols and parameters for vital signs, lab values, decision making and safety to follow when working with ICU patients. (7), (10), (11) The usefulness of this information for PTs treating patients with TAH is somewhat limited due to the fact that these patients have undergone cardiectomy for device implantation. (12) Common parameters to assess tolerance to activity such as heart rate and heart rhythm are no longer applicable. In addition, research has shown that patients who have a TAH do not have the same blood pressure response as patients with other ventricular assist devices. (13)

There is currently limited guidance available regarding specific PT intervention following TAH implantation. (12) One case study is available, but in that case PT was not consulted until one week after implantation. (12) A comparison of blood pressure response in patients following TAH implantation versus left ventricular assist device implantation is available, but does not provide any specific information regarding a PT intervention performed in the acute period following implantation. (13) There is information available regarding a PT for a patient in the ICU with a biventricular assist device, (14) but that device did not require cardiectomy for implantation, which changes how a patient can be monitored during care.

Since the goal of TAH implantation is bridge to heart transplant, it is important to do as much as possible to prevent the negative effects of immobility, so that patients can both survive the transplant and have better outcomes following transplant. Patients with TAH will be found in the ICU immediately following implantation, where PTs are well situated to promote mobility in these patients, but given their medical acuity, interventions must be performed safely as well as effectively. The purpose of this case study is to describe PT evaluation and treatment with a focus on early mobilization in the ICU for a patient following TAH implantation. In accordance with the Health Insurance, Portability, and Accountability Act requirements, the patient involved in this case signed consent for information regarding his case to be published.

CASE PRESENTATION

The patient in this case was a 49-year-old male admitted to the University of Michigan Health System for management of acute heart failure and left ventricular assist device versus heart transplant evaluation. His past medical history included non-ischemic dilated systolic heart failure, pulmonary hypertension, unstable angina, atrial fibrillation, internal cardiac defibrillator placement, hypertension, obstructive sleep apnea, dermal mycosis, gout, and osteoarthritis. His hospital course was complicated by multiple episodes of ventricular tachycardia as well as torsades leading to TandemHeart (CardiacAssist, Inc. Pittsburgh, PA) placement on day 17 of admission which remained in place until implantation of a SynCardia TAH on day 21 of admission. The patient did not receive a PT consult until TAH placement as he was not medically stable to participate in therapy. Immediately upon implantation of TAH, PT was consulted for functional mobility assessment and treatment, development of an individualized exercise program, and to prepare the patient physically for heart transplant. Due to delayed sternal closure and a second visit to the operating room for mediastinal washout, PT evaluated the patient on postoperative day (POD) 2.

Examination

During the initial PT evaluation, the patient was orally intubated for mechanical ventilation. The exam took place during a sedation holiday and the patient's wife was present throughout. The subjective information including home set-up, assistance available, and prior level of function was obtained from the patient's wife. Assessment of cognition and communication were limited but the patient was able to nod and blink appropriately to answer questions and follow all instructions during the exam.

The patient was positioned supine with the head of bed elevated. Range of motion limitations were found in bilateral shoulders as well as the right hip and knee. Assessment of the left lower extremity was limited due to a femoral arterial line and driveline sutures. Strength was assessed in the same position by asking the patient to perform the movement actively against gravity. Deficits were noted in bilateral knee extension and ankle dorsiflexion/plantarflexion. Further resistance testing was not performed due to sternal precautions, multiple lines and tubes present, as well as patient positioning. The patient identified pain in bilateral shoulders, sternal incision, and right groin. Auscultation of anterior lung fields revealed mechanical heart sounds, but no adventitious lung sounds. Light touch and pressure sensation were intact. Visual inspection of the skin identified incisions present at the sternum, the abdomen for the driveline, as well as the presence of numerous lines and tubes related to ventilation, medication administration and monitoring various vital signs.

Although the original plan involved assessment of functional status and endurance, these were not assessed at the time of initial examination due to pain. The patient was extubated the day after the initial PT evaluation. Functional mobility was assessed daily thereafter during PT treatment sessions as tolerated by the patient.

Intervention

All therapists had previous cardiovascular ICU experience and underwent additional training given by SynCardia staff. The training focused on changing power source, alarms, controller changes, monitoring ventricular fill volumes and cardiac output, the diagnostic utilities display and waveforms on the console, and crisis management involving the TAH. Each therapist then had to pass a competency which included a verbal test as well as demonstration of skill. Intervention began with bed exercises and was progressed through bed mobility, seated exercises, transfer training, standing exercises, standing balance activities, and gait training (Table 1), which is similar to the progression of mobilization activities outlined in previous early mobility research (10), (11) as well as the progression of activity used in previous TAH and biventricular assist device cases. (12), (14) Initial sessions involved a PT, occupational therapist, nurse, perfusionist, and rehabilitation technician. This multi-disciplinary approach was fueled in large part by the need for assistance in managing numerous lines in addition to the TAH console and portable oxygen tank as well as the extra assistance needed by the patient due to weakness and pain. As the patient progressed and required less assistance for mobility, sessions involved a PT, nurse, and technician. At this time, the patient was also able to move out of bed to the chair or commode with nursing staff alone and his PT sessions began to focus more on exercises and higher level mobility activities such as progressing gait training and strengthening. This trend is similar to that described by Garzon-Serrano et al.9
Table 1. Progression of Physical Therapy Interventions

POD Key examination Pre BP Post BP Pre Post Pre Post
 findings HR HR LCO LCO

2 Intubated but 137/63 140/68 110 110 5.1 5.2
 not sedated on
 SIMV, pressure
 support 10,
 FiO2 40%, PEEP
 5, Tidal volume
 450. Pain:
 indicated L, R
 shoulder, R
 groin. Limited
 range of motion
 and strength in
 all 4
 extremities.

3 Some dizziness 112/70 120/70 110 110 n/a n/a
 with positional
 changes
 initially, BP
 stable. Report
 of 10/10 pain
 with sitting
 session
 discontinued.

4 On 3 L O2 NC. 150/77 144/66 110 109 6.1 6.4

5 Light headed 140/60 150/70 110 111 5.9 5.9
 when sitting
 EOB.

6 On 2 L O2 NC. 121/57 98/84 110 120 5.7 6
 End of session
 1 L O2 NC.
 Reports working
 hard when
 walking.

7 With ambulation 116/61 n/a 120 120 n/a n/a
 drop in SpO2 on
 room air to 87%
 required 4 L O2
 NC to maintain
 SpO2

8 During activity 99/52 n/a 120 n/a n/a n/a
 de-sats on 2 L
 required 4 L O2
 NC to maintain
 SpO2.

11 On 1 L O2 NC 117/73 121/78 120 120 6.2 6.6
 during gait.
 Repots RPE
 level 11 during
 peak activity,
 some SOB during
 session.

12 Pt requesting 118/75 135/82 120 120 5.6 5.8
 supplemental O2
 despite
 maintaining
 SpO2. Gait
 speed 0.24m/s

13 Pt on room air 100/52 n/a 120 120 5.5 5.5
 during gait.
 Reports working
 somewhat hard
 at peak
 activity.

14 Tolerates 114/75 124/70 120 120 5.1 5.9
 standing for
 25-30 mins
 total.

POD Pre Post Pre L Post L Pre R Post R Pre Post
 RCO RCO fill fill fill fill SpO2 SpO2

2 6.1 5.1 50 48 58 58 98 97

3 n/a n/a 38 40 40 40 n/a n/a

4 7.2 7.2 60 58 68 68 n/a 90

5 6.4 6.5 55 53 56 62 97 98

6 6.6 6.7 53 43 61 54 97 98

7 n/a n/a 52 50 63 60's 99 93

8 n/a n/a 51 65 n/a n/a 94 97

11 7 7.6 51 56 58 62 97 97

12 6.5 6.2 46 42 53 65 94 98

13 6 6 42 42 57 57 95 n/a

14 6.5 6.5 46 47 54 56 97 98

POD Summary of physical
 therapy
 interventions

2 Exercise with
 assist. Education
 on role of PT,
 sternotomy
 precautions,
 lifting
 restrictions, POC
 and progression.

3 Exercise in
 supine.At-tempted
 bed in chair
 position able to
 achieve 75% full
 sitting.

4 Transfers mod to
 max A x 2, sitting
 tolerance edge of
 bed, sit to stand
 transfer, standing
 balance, and
 transfer to
 recliner.

5 Warm up exercise,
 transfers CGA to
 mod A x 2, sitting
 edge of bed,
 transfer to
 recliner, standing
 balance, gait
 training: 5 feet
 with CGA x 2.
 Airway clearance.

6 Exercise,
 transfers, standing
 balance, gait 60
 feet x 2 , CGA x 2,
 with standing rest
 break every 15-20
 feet. Introduced to
 RPE scale.

7 Seated warm up
 exercise with
 assist, gait 180
 feet with 2
 standing rests, CGA
 x 2, hands on TAH
 console.

8 Home exercise
 program,
 stretching, gait
 250 feet with CGA
 hands on TAH, 2-3
 standing rests.

11 Transfers, gait 250
 feet, hands on TAH
 console, standing
 rest break every
 40-50 feet.
 Afternoon: similar
 distance with
 improved cadence
 and fewer rest
 breaks.

12 Transfers, exercise
 including standing
 exercise, standing
 dynamic balance,
 gait 150 feet hand
 held assist x 2,
 standing rest
 breaks every 40-50
 feet.

13 Warm up exercise,
 transfers, standing
 balance, gait 200
 feet, hand held
 assist, standing
 rest every 60-70
 feet.

14 Transfers, standing
 exercise, gait 335
 feet with CGA/ min
 A without assistive
 device, 4 standing
 rest breaks.

L: left, R: Right, min: minimal,mod: moderate, CGA: contact guard
assist, POD: post operative day, BP: Blood pressure ( A line for
initial evaluation to post op day #7), RCO: right cardiac output
(liters/min), LCO: left cardiac output (liters/min), L fill: Left
fill volume (milliliters), R fill: Right fill volume (milliliters),
HR: heart rate (beats/minute) set by TAH, HEP:


Treatment was progressed based on self-reported patient tolerance as well as close monitoring of vital signs, including right and left ventricular fill volumes. Ideally, the fill volumes for each ventricle should be between 50-60 ml and 65 ml was set as the ceiling for activity. We titrated supplemental oxygen accordingly once the patient was on nasal cannula to maintain oxygen saturation above 90%.15 We measured blood pressure with the goal being to avoid decrease in systolic pressure more than 20 mmHg. Subjective complaints such as lightheadedness, dizziness, fatigue, shortness of breath, and pain were also monitored. The Rating of Perceived Exertion scale16 was used with the goal for activity being between 11 (fairly light) and 13 (somewhat hard). These parameters are similar to those used in previous early mobility research as well as those used for patients with TAH or biventricular assist devices (7), (10), (11), (13), (14)

Laboratory values were monitored daily including hemoglobin, platelet count, white blood cell count, anti-coagulation values, calcium, potassium, sodium,

magnesium and chloride. The guidelines used for PT participation (Table 2) were hemoglobin >7.0 gm/dl, platelet count > 10,000 cells/[m.sup.3], white blood cell count between 5-10,000 leukocytes/m[m.sup.3]. Our guidelines for hemoglobin were similar to those used by Stiller and Phillips17 and slightly lower than those advocated by Hanekom et al.11 While the patient was anti-coagulated with heparin, partial thromboplastin time was followed and parameters were 45-99 seconds. When he was switched to warfarin, the international normalized ratio goal was 2.0-3.0. Parameters for PT for calcium were 7.0-12.0 mg/dL, potassium 3.0-6.0 mEq/L, sodium 120-160 mEq/L, magnesium 1.0-5.0 mg/ dL, and chloride 70-108 mM/L. These parameters were not listed in previous TAH or biventricular assist device research that we found. (12-14) All of the above guidelines were developed by physical therapists in conjunction with a general medicine physician and a cardiothoracic surgeon at University of Michigan and are standard for any inpatient receiving physical therapy services at our hospital. As the patient's values were relatively stable, at no time was therapy held due to laboratory values.
Table 2. Laboratory Test Values Used as Guidelines for
Physical Therapy Intervention

Lab Value Guidelines for
 PT

Hemoglobin >7.0 gm/dL

Platelets >10,000
 cells/m3

White Blood 5-10,000
Cells leukocytes/mm3

Partial 45-99 seconds
Thromboplastin
Time

International 2.0-3.0
Normalized
Ratio

Calcium 7.0-12.0 mg/dL

Potassium 3.0-6.0 mEq/L

Sodium 120-160 mEq/L

Magnesium 1.0-5.0 mg/dL

Chloride 70-108 mM/L


Throughout the course of his ICU stay, the patient was on various medications including calcium channel blockers, ACE inhibitors, and diuretics as well as medications for pulmonary hypertension. Since a side effect of most of these medications is hypotension, we monitored blood pressure closely as well as assessing for any subjective complaints of hypotension during therapy sessions.

During early sessions, the primary limiting factor to mobility was pain. The patient complained of pain at incision and driveline sites, but also at his knees due to pre-existing osteoarthritis. Pain was documented using a visual analog scale from 0-10 at times, and at other times was documented subjectively with the patient stating location, whether it was better or worse than previous sessions, and if it was indeed limiting activity during therapy. As the patient progressed, the primary focus became gait training and standing exercises and the limiting factor became shortness of breath. Initially the patient did experience some de-saturation requiring titration of supplemental oxygen to maintain oxygen saturation above 90%. (15) Towards the last few sessions, the patient continued to complain of shortness of breath despite maintaining acceptable oxygen saturation on one liter supplemental oxygen or even on

room air. The patient was encouraged to perform standing rests as needed which allowed for resolution of symptoms. No objective measures of shortness of breath were used with this patient.

Outcome

The patient's functional mobility improved with each treatment session as evidenced by increasing independence with bed mobility, transfers and gait (Table 1). The patient's lower extremity strength, as measured by his ability to perform sit-to-stand transfers with decreasing assistance provided, also improved from initial attempt on POD 4 to the time of his heart transplant. The patient's functional endurance also improved as evidenced by his ability to walk farther with fewer rest breaks. No adverse events or complications occurred due to PT in this case. The patient received an orthotopic heart transplant on POD 15 and was discharged to his home with the assistance of his family 15 days following his heart transplant.

DISCUSSION

Given the nature of surgical intervention involved for TAH implantation and the medical acuity of those patients who require such a device, patients are admitted to the ICU following device implantation. Although there is a growing amount of research regarding the role of PT for patients in the ICU under the heading of early mobility, there is none that specifically involves early mobility for patients with a TAH. Because implantation of a TAH involves cardiectomy, the care these patients require is unique. Current research regarding PT for patients with TAH either begins later in the patient's hospital stay (12) or does not provide any details of the immediate postoperative phase. (13) Senduran and colleagues (14) provide details of PT treatment for a patient POD one, but in that case the patient had a biventricular assist device, which does not require cardiectomy and is therefore different than a TAH. Kohli et al (13) found a trend towards improved survival to transplant with earlier PT intervention and yet, the median time to intervention in that research was 5 days following device implantation. Perhaps this trend would be similar or even more pronounced if mobility were begun even sooner. Our case report is the only one thus far to detail PT treatment beginning POD 2 following TAH.

Neither Kohli et al (13) nor Senduran and colleagues (14) provide specific information regarding PT findings at the initial patient evaluation. Nicholson and Paz (12) give information regarding the functional mobility of the patient at evaluation. In that case, the patient required less assistance for all mobility than our patient. However, following two weeks of PT intervention, our patient was ambulating 335 feet (102 meters) with contact guard/ minimal assistance without an assistive device, whereas the patient in Nicholson and Paz's case was ambulating 150 feet (46 meters). (12) As the distance required for community ambulation increases, (19) the ability to walk further can be an important factor in whether a patient discharges to home or an inpatient rehabilitation setting. Given that these are case reports, it is not possible to say that the earlier intervention was responsible for the better functional outcomes in a shorter time span in this case. But as the trend in research shows early mobility leads to decreased time needed to meet mobility milestones, (7) it would be beneficial to attempt to replicate this data with patients who have a TAH implanted.

One of the aims of PT in this case was to prepare the patient physically for heart transplant. Following his orthotopic heart transplant, the patient was able to return to his home in 15 days. This was the average length of stay for a heart transplant patient at our facility at the time the patient was seen, thus early mobility may not have had any effect on the patient's length of stay. However, this patient was admitted to the hospital 21 days before he underwent TAH implantation, the last 6 of which he was completely immobilized for TandemHeart placement and then TAH surgical implantation. Given that this is a case study, no causative conclusions can be drawn, however, despite his prolonged hospitalization prior to heart transplant, his post-operative transplant course was typical. He did not acquire pneumonia or any skin breakdown during his stay and he did not need further inpatient based rehabilitation following his hospital discharge.

One of the most critical vital signs we monitored during PT sessions was the ventricular fill volumes. The TAH is set to partially fill both ventricles at rest, to allow for increased filling due to increased preload with activity. In the case of this patient, the right fill volumes were consistently higher than the left fill volumes according the monitor on the TAH console. This is actually an artifact of some back flow of blood through the right outflow valve. As the pressure on this valve is not as great as the pressure on the left side, the valve takes slightly longer to close, allowing for some regurgitation. This is reflected in the right fill volume measurement as well as the right cardiac output measurement. If the right cardiac output were truly higher than the left side, the patient would experience an increase in left fill volume until the ventricle reached its maximum capacity at which time the patient would experience pulmonary edema. On POD 4 the patient experienced a slight decrease in blood pressure when moving from supine to seated in a chair for the first time. However, it was not enough to cause a drop in his fill volumes or his cardiac output. On POD 6, the patient again experienced a decrease in blood pressure following therapy. This time the change was larger and was accompanied by a decrease in fill volumes. The patient's heart rate setting was changed by the medical team during this time and consequently his cardiac output remained stable. On POD 12-14, it was noted that fill volumes and cardiac output, especially in the left ventricle were decreased. This was likely due to decreased blood volume as the patient was diuresed over the course of his stay. It did not seem to impact the patient's activity level as he continued to progress in both exercise and ambulation tolerance.

Limitations

No muscle or movement specific objective measurements of strength were taken either at evaluation or during follow up. Gait speed (18) was assessed once during treatment, but was not tested again as the patient received his heart transplant soon after that. Although the Borg scale of perceived exertion was used to assess tolerance to and progress the patient's activity level, the specific ratings given by the patient during sessions were not documented consistently. Objective measures for shortness of breath were also not utilized. In future, it would be beneficial to have more objective measures documented to promote best practice for these patients.

CONCLUSION

Early mobilization in this case of a patient following TAH implantation was well tolerated and safe. The patient achieved functional mobility that was as good as or better than that previously reported. (2), (12) This case demonstrates that there are situations within which it is appropriate and safe to involve PT very early in the mobilization of patients after TAH implantation. Future research is warranted and should involve studies with a larger population size to gather more information regarding patient tolerance to activity and outcomes following early mobilization by PT.

REFERENCES

(2.) Copeland JG, Smith RG, Arabia FA, et al. Cardiac replacement with a total artificial heart as a bridge to transplantation. N Engl J Med. 2004;351(9):859-867.

(3.) Leprince P, Bonnet N, Rama A, et al. Bridge to transplantation with the Jarvik-7 (CardioWest) total artificial heart: a single-center 15-year experience. J Heart Lung Transplant. 2003;22(12):1296-1303.

(4.) Mullen GM, Malinowska K, Lawless CE, et al. Cardiowest total artificial heart as an excellent bridge to cardiac transplantation. Transplantation. 1999;67(7):S253.

(5.) Roussel J, Senage T, Baron O, et al. CardioWest (Jarvik) total artificial heart: a single-center experience with 42 patients. Ann Thorac Surg. 2009;87(1):124-130.

(6.) Copeland JG, Arabia FA, Tsau, PH, et al. Total artificial hearts: bridge to transplantation. Cardiol Clin. 2003;21:101-113.

(7.) Adler J, Malone D. Early Mobilization in the intensive care unit: a systematic review. Cardiopulm Phys Ther J. 2012;23(1):5-13.

(8.) Morris PE, Goad A, Thompson C, et al. Early intensive care unit mobility therapy in the treatment of acute respiratory failure. Crit Care Med. 2008;36(8):2238-43.

(9.) Garzon-Serrano J, Ryan C, Waak K, et al. Early mobilization in critically ill patients: patients' mobilization level depends on health care provider's profession. PM R. 2011;3:307-313.

(10.) Perme C, Chandrashekar R. Early mobility and walking program for patients in intensive care units: creating a standard of care. AJCC. 2009;18(3):212-221.

(11.) Hanekom S, Gosselink R, Dean E, et al.The development of a clinical management algorithm for early physical activity and mobilization of critically ill patients: synthesis of evidence and expert opinion and its translation into practice. Clin Rehabil. 2011;25(9):771- 787.

(12.) Nicholson C, Paz JC. Total artificial heart and physical therapy management. Cardiopulm Phys Ther J. 2010;21(2):13-21.

(13.) Kohli HS, Canada J, Arena R, et al. Exercise blood pressure response during assisted circulatory support: comparison of the total artificial heart with a left ventricular assist device during rehabilitation. J Heart Lung Transplant. 2011;30:1207-1213.

(14.) Senduran M, Malkoc M, Oto, O. Physical therapy in the intensive care unit in a patient with biventricular assist device. Cardiopulm Phys Ther J. 2011;22(3):31- 34.

(15.) American Physical Therapy Association. Oxygen administration during physical therapy. American Physical Therapy Association. http://www.apta.org/OxygenAdministration/. Updated February 20, 2013. Accessed January 3, 2014.

(16.) Borg G. Perceived Exertion as an Indicator of Somatic Stress. Champaign, IL: Human Kinetics; 1998.

(17.) Stiller K, Phillips A. Safety aspects of mobilising acutely ill inpatients. Physiother Theory Pract. 2003;19:239- 257.

(18.) Fritz S, Lusardi M. Walking speed: the sixth vital sign (White Paper). J Geriatr Phys Ther. 2009;32(2):2-5.

(19.) Andrews AW, Chinworth SA, Bourassa M, et al. Update on distance and velocity requirements for community ambulation. J Geriatr Phys Ther. 2010;33:128-134.

Natalia Fernandez, MS, CCS; Kimberly Ford, MSPT

University of Michigan Health System, Department of Physical Medicine and Rehabilitation

Address correspondence to: Natalia Fernandez, MS, CCS, University of Michigan Hospital, 1F245, 1500 East Medical Drive, Ann Arbor, MI 48109
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Author:Fernandez, Natalia
Publication:Cardiopulmonary Physical Therapy Journal
Article Type:Author abstract
Date:Mar 1, 2014
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