Postoperative Respiratory failure( PRF) Dr.Ahmad farooq

Postoperative Respiratory failure( PRF) Dr.Ahmad farooq

Is it really or/only a postoperative issue Multi hit theory first hits second hits

Definition Pulmonary gas exchange impairment that presents after a surgical procedure and as a result of the changes induced by anesthesia and surgery with ABG,s measurement providing the grounds for diagnosis: PaO2< 60 mmhg (Fio 2 0.21) Pco2 > 50 mm of hg P/F < 300 mm of hg

ACS-NSQIP definition of PRF Unplanned intubation during surgery or postoperatively Reintubation once extubated Mechanical ventilation for > 48 h postoperatively.

Severity According to the recent international consensus on ARDS, PRF may be classified as Mild (PaO2/FIO2 300mmHg and>200mmhg) Moderate (PaO2/ FIO2 200 mmhg and > 100 mmhg) Severe (PaO2/FIO2 100 mmhg)

Pathogenesis Primarily reduction of respiratory muscle tone leading to abnormal gas exchange and ventilation-perfusion mismatch and shunt aggravated by factors such as hypoventilation due to the residual effects of anesthetics, lung edema, laryngospasm, and bronchospasm and increased Fio2 > 80% during surgery and manipulation of structures above or below the diaphragm during surgery

PRF PREDICTORS FIRST HITS Threats associated with the patient s condition and the foreseen procedure (preoperative information). SECOND HITS Intraoperative events, which would modulate first-hit risk and indicate the patient s definitive risk.

Preoperative Age Male ASA of at least 3 FUNCTIONAL DEPENDENCY Sepsis/sep tic shock CHF COPD Prolonged hospitalization DM GERD Alcohol abuse Current smoker Liver disease Weight loss cancer Dyspnea HTN Renal failure Surgery Cardiac Vascular Thoracic Upper abdominal Emergenc y Neck Urology Neurosurgery General Burn Transplant High risk surgery INTRAOPERATIVE Pulmonary driving pressure Inspired oxygen fraction Volume of crystalloid administration Erythrocyte transfusion Duration of surgery No. of anesthetics during admission

PREVENTION OF POSTOPERATIVE RESPIRATORY FAILURE

VENTILATORY( LUNG PROTECTIVE VENTILATION) Accurate FIO2( upto 80% does not promote atelectasis) Avoid volume trauma by 1) limit plateau pressure to 20 cm of h20 2) limit tidal volume to 6ml/kg in all non-risk and high risk patients Avoid Atelectrauma 1)Peep 2)Recruitment maneuvers after intubation,disconnection, durring hypoxia and before extubation Severgnini P, Selmo G, Lanza C, et al. Protective mechanical ventilation during general anesthesia for open abdominal surgery improves postoperative pulmonary function. Anesthesiology 2013; 118:1307 1321. A comprehensive ventilation strategy (low tidal volumes, PEEP, and recruitment maneuvers) can improve postoperative pulmonary function. Futier E, Constantin JM, Paugam-Burtz C, et al. A trial of intraoperative low-tidalvolume ventilation in abdominal surgery. N Engl J Med 2013; 369:428 437.

NON VENTILATORY Anesthetic technique (i) Choose neuroaxial or regional techniques (ii) Inhaled anesthetics to decrease pulmonary inflammatory response to mechanical ventilation (iii) Accurate administration and monitoring of neuromuscular block Emergence (i) Complete reversal of the neuromuscular Blockade (ii) No atelectasis (iii) Adequate postoperative analgesia (iv) Avoid overuse of opiates and excessive sedation Restrictive use of fluids Avoid transfusion (i) Alleviate preoperative anemia (ii) Apply blood saving strategies Decrease risk of pulmonary infection (i) Antibiotic prophylaxis (ii) Tooth brushing and oral decontamination (iii) Orotracheal tube management Check cuff pressure Appropriate cuff shape Appropriate material (iv) Avoid nasogastric tubes Surgical technique (i) Choose a thoracoscopic or laparoscopic Approach (ii) Reduce surgical duration (iii) Defer surgery whenever possible

POSTOPERATIVE NOINVASIVE VENTILATION Use in selected patient groups may reduce the incidence of postoperative hypoxia, respiratory failure, rates of reintubation, incidence of pneumonia, ICU and hospital length of stay, and potentially mortality. NIV must be delivered via a tight-fitting mask or helmet. Problems with interface fit, leakage, and patient discomfort are frequently encountered The question of treating with NIV can become a balance of the costs incurred through equipment, disposables, staffing, and critical care bed provision against the potential savings made by preventing complications and reducing length of stay.

HIGH-FLOW NASAL OXYGEN Delivery of air oxygen mixtures at inspiratory flow rates of up to 60 L/min, which reduces the amount of ambient air entrainment and allows a more reliable and predictable FiO2 delivery to patients Pharyngeal dead-space washout, alveolar recruitment, and reduced airflow resistance and variable degree of PEEP, 3 7 cm H20 which all promote enhanced respiratory parameters and gas exchange Improved oxygenation and 90-day survival in patients with acute hypoxic RF when compared to NIV Reduced extubation failure and reintubation rates in postoperative patients and icu as well

Physiotherapy Techniques Multimodal specialty including early assisted mobilization, exercise, thoracic expansion exercises, incentive spirometry, and airway clearance techniques. PEP therapy patients generate an expiratory pressure of up to 20 cm H20 by breathing against a mouthpiece valve device, may also be used postoperatively to increase functional residual capacity and mobilize secretions NO strong evidence to suggest that PEP is beneficial when applied routinely. However, physiologically in postoperative patients with increased sputum production, or to ameliorate sputum retention, especially in patients with dynamic airway collapse or atelectasis.

A 75y/M, know case of uncontrolled DM, severe COPD with FEV 1 <30% and corpulmonale has small swelling of Rt lower arm(probably lipoma) which is asymptomatic with no pain or any neurovascular involvement. You did preoperative assessment, following which you went to surgeon to discuss the plan of surgery and anesthesia. What will be most appropriate plan for this pt? 1. GA with lung protective ventilation 2. Iv sedation with local application 3. Supraclavicular block 4. Defer the surgery 5. GA with high tidal volumes

Uncoupling of the link between unconsciousness and upper airway dilator muscle hypotonia is by 1. Etomidate 2. Propofol 3. Thiopental 4. Midazolam 5. None of the above

Respiratory arousal is not characterized by 1. Increased chemo responsiveness to hypoxia 2. Increased chemo responsiveness to hypercarbia 3. Suppression of reflex responsiveness to negative upper airway pressure 4. Increase in the magnitude of wakefulness

Regarding role of muscles in PRF 1. In awake pt upper airways muscles have constrictor(narrowing) effect 2. Expiratory pump muscles have no role in development of PRF 3. Tensor palatine is involved in Negative pressure reflex. 4. Genioglossus has no phasic neuronal input during respiratory cycle 5. Tone of respiratory pump muscles increases FRC BY 0.8L