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Individualizing Sedation in Acute Respiratory Distress Syndrome Patients on Extracorporeal Membrane Oxygenation

Shekar, Kiran; Grewal, Jatinder; Lisa Sutt, Anna; Fraser, John

doi: 10.1097/MAT.0000000000000969
Letters to the Editor
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Adult Intensive Care Services, The Prince Charles Hospital, Brisbane, Queensland, Australia, Critical Care Research Group and Centre of Research Excellence for Advanced Cardio-respiratory Therapies Improving OrgaN Support (ACTIONS), Brisbane, Queensland, Australia, University of Queensland, Brisbane, Queensland, Australia, Bond University, Gold Coast, Queensland, Australia

Royal Brisbane and Women’s hospital, Brisbane, Queensland, Australia

Critical Care Research Group and Centre of Research Excellence for Advanced Cardio-respiratory Therapies Improving OrgaN Support (ACTIONS), Brisbane, Queensland, Australia, University of Queensland, Brisbane, Queensland, Australia, Speech and Language Therapy, St. Bartholomew’s Hospital, Barts NHS Trust, London, United Kingdom

Critical Care Research Group and Centre of Research Excellence for Advanced Cardio-respiratory Therapies Improving OrgaN Support (ACTIONS), Brisbane, Queensland, Australia, University of Queensland, Brisbane, Queensland, Australia

Disclosure: The authors have no conflicts of interest to report.

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To the Editor:

DeBacker et al.1 report sedation practice in acute respiratory distress syndrome (ARDS) patients supported with extracorporeal membrane oxygenation (ECMO)—a practice that is complicated by the physiology of the patient and altered pharmacokinetics (PK).2 Waking and mobilizing these patients is no mean feat but is feasible3 in selected patients, especially when the lung disease is less severe or recovering.

Minimizing iatrogenic lung injury is the key principle that guides management on ECMO, including sedation. There are currently no evidence-based guidelines for mechanical ventilation practice on venovenous (VV) ECMO, although the major benefits of VV ECMO are based on minimizing stretch and further lung injury.4 The “lung rest” strategies designed at minimizing secondary lung injury create a situation of near-total ECMO dependence with little or no contribution from patient lungs. The resultant shunting and deoxygenation across native lungs may necessitate higher ECMO blood flows, especially in patients with higher cardiac output. Attempts to reduce sedation and waken patients who have been made volume deplete in an attempt to optimize native lung function may induce a precipitous drop blood flow and can lead to a hypoxic crisis if the native lungs are still dysfunctional. Greater intravascular volume and a large multistage drainage cannula, well positioned in the inferior vena cava anecdotally are associated with less respiratory perturbations on reducing sedation. Therefore, the proven benefits of interruption of sedation must be weighed up against the equally well-proven risks associated with increasing fluid balance. Dexmedetomidine is a useful adjunct in this setting. Apart from its antianxiety, sedative, and analgesic properties, its negative chronotropic effects reduce cardiac output, thereby reducing the pulmonary shunt, although its vasodilatory effects can drop venous return.

Safety and comfort are important considerations too. Accidental decannulation can be frequently fatal. Extubation, where possible may overcome tube intolerance. Breathing spontaneously through their poorly complaint lungs is a challenging physiologic adaption for patients.5 Lowering carbon dioxide content by increasing fresh gas flows may minimize the respiratory drive, ventilator desynchrony and hence sedation. Early tracheostomy may help minimize sedation requirements and may reduce duration of ECMO6 with added patient-centered benefits such as potential ability to eat and drink and vocalize.7 Certainly, there is a need to investigate the risk: benefits of an early tracheostomy in this patient population.

Knowledge of altered PK2 can inform choice of sedative and analgesic drugs. Hydrophilic agents such as morphine are less sequestered in ECMO circuits8,9 and may have greater bioavailability. Although benzodiazepines are significantly sequestered and necessitate higher doses, they are widely used given their better cardiovascular tolerance, compared with propofol. Enteral longer-acting benzodiazepines, antipsychotics, methadone, and physical restraints can all be useful adjuncts in minimizing intravenous sedation requirements.

Sedation practice in respiratory failure patients treated with ECMO remains variable10 in the absence of robust data to guide practice. Clinicians continue to individualize sedation not based just on their patient’s physiologic needs but also on center experience, culture, resources, staffing, etc. Long-term prospective studies are indicated to guide the clinician, as the use of ECMO continues to grow.

Kiran Shekar

Adult Intensive Care Services

The Prince Charles Hospital

Brisbane, Queensland, Australia

Critical Care Research Group and Centre of Research

Excellence for Advanced Cardio-respiratory Therapies

Improving OrgaN Support (ACTIONS)

Brisbane, Queensland, Australia

University of Queensland

Brisbane, Queensland, Australia

Bond University

Gold Coast, Queensland, Australia

Jatinder Grewal

Royal Brisbane and Women’s hospital

Brisbane, Queensland, Australia

Anna Lisa Sutt

Critical Care Research Group and Centre of Research

Excellence for Advanced Cardio-respiratory Therapies

Improving OrgaN Support (ACTIONS)

Brisbane, Queensland, Australia

University of Queensland

Brisbane, Queensland, Australia

Speech and Language Therapy

St. Bartholomew’s Hospital

Barts NHS Trust

London, United Kingdom

John Fraser

Critical Care Research Group and Centre of Research

Excellence for Advanced Cardio-respiratory Therapies

Improving OrgaN Support (ACTIONS)

Brisbane, Queensland, Australia

University of Queensland

Brisbane, Queensland, Australia

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References

1. deBacker J, Tamberg E, Munshi L, Burry L, Fan E, Mehta S. Sedation practice in extracorporeal membrane oxygenation-treated patients with acute respiratory distress syndrome: A retrospective study. ASAIO J 2018.64: 544–551.
2. Shekar K, Fraser JF, Smith MT, Roberts JA. Pharmacokinetic changes in patients receiving extracorporeal membrane oxygenation. J Crit Care 2012.27: 741 e9–e18.
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6. Boulos FM, Raithel M, Brigante F, et al. Time to tracheostomy: Early tracheostomy may decrease the duration of extracorporeal membrane oxygenation support in patients with acute respiratory distress syndrome. J Am Coll Surg 2017.225: S65.
7. Sutt AL, Cornwell P, Mullany D, Kinneally T, Fraser JF. The use of tracheostomy speaking valves in mechanically ventilated patients results in improved communication and does not prolong ventilation time in cardiothoracic intensive care unit patients. J Crit Care 2015.30: 491–494.
8. Shekar K, Roberts JA, Barnett AG, et al. Can physicochemical properties of antimicrobials be used to predict their pharmacokinetics during extracorporeal membrane oxygenation? Illustrative data from ovine models. Crit Care 2015.19: 437.
9. Shekar K, Roberts JA, McDonald CI, et al. Sequestration of drugs in the circuit may lead to therapeutic failure during extracorporeal membrane oxygenation. Crit Care 2012.16: R194.
10. Marhong JD, DeBacker J, Viau-Lapointe J, et al. Sedation and mobilization during venovenous extracorporeal membrane oxygenation for acute respiratory failure: An international survey. Crit Care Med 2017.45: 1893–1899.
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