Postoperative ARDS

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Postoperative Acute Respiratory Distress Syndrome

• Prepared by Dr.Osamah

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• Post-operative ARDS
• Definition-
• ARDS is an acute, diffuse, inflammatory lung
  injury precipitated by a predisposing risk
  factor, and it's
• a life threatening respiratory disease process
  characterized by hypoxemia and diffuse
  radiographic opacities associated with increased
  shunting, increased alveolar dead space, and
  decreased lung compliance, and it is one of the
  more serious postoperative pulmonary
  complications.
• Its incidence lengthen the hospitalization,
  ventilation time, and time spent in intensive
  care, and profoundly increase the risk of
  mortality and significant morbidity.
• The incidence among critically ill patients in
  intensive care units (ICUs)is 10 and the
  mortality rate is 40 ,Among those with ARDS, the
  majority (47 percent) had moderate ARDS while the
  remainder had mild (30 percent) or severe disease
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Diagnostic criteria for the new global definition
of ARDS 1-Presence of Risk factors (Acute
predisposing risk factor) such as trauma patient
blood transfusion, aspiration, or shock
patient.... 2-Timing -Acute onset or worsening
of hypoxemic respiratory failure within 1 week of
the estimated onset of the predisposing risk
factor. 3- chest imaging -Bilateral opacities
on chest radiography and computed tomography or
bilateral B lines and/or consolidations on
ultrasound not fully explained by effusions,
atelectasis, or nodules/mass.
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• Diagnostic criteria for the new global definition
  of ARDS
• 4-Oxygenation-
• for Intubated patients
• Mild200 lt PaO2FIO2 300 mmHg or 235 lt SpO2FIO2
  315 (if SpO2 97)
• Moderate 100 lt PaO2FIO2 200 mmHg or 148 lt
  SpO2FIO2 235 (if SpO2 97)
• Severe PaO2FIO2 100 mmHg or SpO2FIO2 148 (if
  SpO2 97).
• non-intubated -
• PaO2FIO2 300 mmHg or SpO2FIO2 315 (if SpO2
  97) on HFNC with flow of 30 L/min or NIV/CPAP
  with at least 5 cm H2O end-expiratory pressure.

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• Etiology Risk factors-
• 1-Sepsis
• 2-Aspiration pneumonitis
• 3-Infectious pneumonia (including mycobacterial,
  viral, fungal, parasitic)
• 4-Severe trauma and/or multiple fractures
• 5-Pulmonary contusion
• 6-Burns and smoke inhalation
• 7-Transfusion related acute lung injury and
  massive transfusions
• 8-HSCT
• 9-Pancreatitis
• 10-Inhalation injuries other than smoke (e.g.,
  near drowning, gases)
• 11-Thoracic surgery (e.g., post-cardiopulmonary
  bypass) or other major surgery(
  Vascular,Pulmonary, upper Abdominal surgeries).
• 12-Drugs (chemotherapeutic agents, amiodarone,
  radiation)
• 13-Other risk factors-cigarette smoking,
  pneumonectomy, obesity, blood type A, and
  exposure to particulate matter with an
  aerodynamic lt2.5 micrometers (PM2.5) and ozone.

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• Clinical Manifestations
• the manifestations are so nonspecific that the
  diagnosis is often missed until the disease
  progresses.
• clinical presentation is influenced by medical
  management (position, sedation, paralysis,
  positive end-expiratory airway pressure, and
  fluid balance).
• ARDS should be suspected in patients with
  progressive symptoms of dyspnea, an increasing
  requirement for oxygen, and alveolar infiltrates
  on chest imaging within 6 to 72 hours of an
  inciting event or up to a week.

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• Clinical Manifestations
• History and physical examination-
• -dyspnea
• -reduction in arterial oxygen saturation
• -On examination patients may have tachypnea,
  tachycardia, and diffuse crackles.
• - When severe, acute confusion, respiratory
  distress, cyanosis, and diaphoresis may be
  evident
• -Cough, chest pain, wheeze, hemoptysis, and fever
  are inconsistent and mostly driven by the
  underlying etiology.

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• Laboratory investigations and Imaging
• 1-ABG
• 2-Blood tests (WBC,KFT,LFT,PT,PTT, D-Dimer ...)
• Imaging Imaging findings are variable and
  depend upon the severity of ARDS.
• 1-Chest X-ray -

Chest radiograph showing diffuse, bilateral,
alveolar infiltrates without cardiomegaly in a
patient with ARDS.
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• Contin... Imaging-
• 2-Chest CT scan-

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Chest CT scan of pt with
ARDS (ground glass ap).
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• Bedside lung ultrasound remains investigational
  but preliminary studies report an 83 to 92
  percent sensitivity for the diagnosis of ARDS
  compared with CT chest.
• Findings of the inciting event(underlying
  predisposing factors)

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• Management of Postoperative ARDS
• A. Preoperative management-
• Preoperative objectives include the
  identification of patients at risk for developing
  ARDS (using general risk factors and scoring
  systems) and optimization of these patients where
  possible.
• Identification of general risk factors for
  developing ARDS(as mentioned before).
• (2) Risk prediction scores for ARDS.
• -The Surgical Lung Injury Prediction 2 model
  (SLIP2).
• -The Lung Injury Prediction (LIP) Score.
• -More recently, early oxygen saturation to
  fraction of
• inspired oxygen ratio (within 6 hours of hospital
  
• admission) has been shown to be an independent
• indicator of ARDS development in patients at risk
  of ARDS.

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• Patient Optimization
• 1-Treatment of respiratory infections
• 2-Control any Chronic lung disease e.g. COPD and
  asthma
• 3-Optimize the nutritional status of the patients
• 4-Smoking cessation
• 5-Preoperative physiotherapy
• 6-Routine approaches to reduce gastric aspiration
  and ventilator-associated pneumonia should be
  employed.

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Intraoperative Management
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• Postoperative Management of ARDS
• Planned ICU admission is suggested for patients
  at high risk to develop ARDS.
• Oxygenation and Mechanical Ventilation-
• start oxygen support by non-rebreather face mask
  then HFNC --gt if no response or the patient
  condition deteriorated don't delay Intubation and
  mechanical ventilation.
• Lung-Protective Mechanical ventilation strategy
  is the cornerstone of ARDS management.
• This Include the use of low VT to minimize
  barotrauma and lung injury and maintain low
  plateau pressure (Pplat), lower driving pressure
  (?P) with moderate levels of PEEP.

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Supportive care 1-Sedation and analgesia
2-Neuromuscular blockade if severe
ARDS. 3-Haemodynamic monitoring/management via
CVC 4-Nutritional support (enteral) 4-Glucose
control 6-VAP prevention and treatment 7-DVT
prophylaxis 8-Gastrointestinal (stress ulcers)
prophylaxis
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Thank you

• References-
• - Up-to-date
• -National library of medicine
• -Southern African Journal of Anesthesia and
  Analgesia 2018
• -Journal of Thoracic Disease, Vol 8, No 10
  October 2016