1. Negative Pressure Pulmonary Edema
Laryngospasm and
Negative Pressure Pulmonary Edema
พญ.สุดารัตน์ ศุภกิจเจริญ
หน่วยงานวิสัญญี โรงพยาบาลกำแพงเพชร

2. Laryngospasm is a form of airway obstruction.
Laryngospasm is usually easily detected and managed, but may present atypically and/or be precipitated by factors which are not immediately recognized.
If poorly managed, it has the potential to cause morbidity and mortality such as severe hypoxaemia, pulmonary aspiration, and post-obstructive pulmonary edema.

3. SIGNS Inspiratory stridor/airway obstruction
Increased inspiratory efforts/tracheal tug
Paradoxical chest/abdominal movements
Desaturation
Bradycardia esp.in children
Central cyanosis

4. THINK OF Airway irritation and/or obstruction
Blood/secretions in the airway
Regurgitation and aspiration
Excessive stimulation/“light” anaesthesia

5. MANAGEMENT Recognise Laryngospasm Apply CPAP c 100% O2
c airway maneuver
Assess O2 entry
Bag movement No
Some
Complete laryngospasm
Partial laryngospasm

6. Complete laryngospasm Partial laryngospasm
Consider specialized
Maneuver to convert
to partial laryngospasm
Eliminate stimulus ex.secretion
Deepen anesthesia c volatile
or porpofol
not improvement
Reassess O2 entry
No iv assess
iv assess
Improvement
suxa 1-2 mg/kg iv
+/- atropine 0.02mg/kg iv
suxa 3-4 mg/kg im
+/- atroine 0.02 mg/kg im
CPAP ventilate c 100%O2
Attempt intubation as appropriate
Improvement
Stabilise and resume
anesthesia +/- NG tube
Not improved
CPR + ACLS
as indicated

7. Specialised maneuver Pressure in laryngospasm notch
Pull mandible forward = forcible jaw thrust

8. Negative Pressure Pulmonary Edema

9. Mechanism of Edema Formation
Two theories on the edema fluid formation
One of the theory suggests significant fluid shifts due to changes in intrathoracic pressure and hydrostatic transpulmonary gradient due to increased blood flow in pulmonary vessel.
The second proposed mechanism involves the disruption of the alveolar epithelial and pulmonary microvascular membranes from severe mechanical stress which leads to increased pulmonary capillary permeability and protein-rich pulmonary edema.

10. Negative Pressure Pulmonary Edema
Inspiratory efforts against a closed glottis (modified Mueller maneuver) may result in pleural pressures (> cm H2O)
Hypoxic pulmonary vasoconstriction
These changes result in:
Increased transmural pressure
Fluid filtration into the lung
Development of pulmonary edema and capillary failure.

11. Development of NPPE

12. Mechanism of Negative Pressure Pulmonary Edema10
Pulmonary edema remains 1
An upper airway obstruction occurs 9 2
Airway obstruction is relieved
The patient continues trying to inhale against the obstruction 8 3
Fluid from the interstitial space floods into the alveoli
A high degree of negative intra-thoracic pressure develops 7
A disruption in the alveolar membrane junction occurs 4
Venous return to the heart increases 6 5
Pressure in the pulmonary capillary bed increases
Cardiac output decreases

13. Normal Respiration
-1cm H2O
+1cm H2O

14. Normal Pressure - Oncotic Pressure (25mmHg)
- Osmotic Pressure (15mmHg)

15. Airway Obstruction
-1cm H2O

16. Altered pressure

17. Alveolar Membrane

18. Risk assessment Laryngospasm Obesity, OSA Young male athlets
Epiglotitis
Croup
Partial trachial obstruction by FB
Upper airway pathology ex .laryngomalacia, vocal cord paralysis
Obstructed ETT or LMA
Difficult intubation, nasal, oral or pharyngeal
Surgical site ex. Oropharynx,neck,urogenital
Extubation during light planes of anesthesia
Secretions falling on the vocal cords.

19. Signs and Symptoms Frothy pink pulmonary secretions : Hallmark sign
Tachycardia,hypertension
Diaphoresis
Auscultation : Rales,Occasionally wheezing
Hypoxemia on pulse oximetry or ABG
Bilateral, alveolar infiltrates on chest x-ray

20. CXR

21. Differential diagnosis
ARDS
Intravascular volume excess
Cardiac abnormalities
Pulmonary emboli

22. Treatment Early diagnosis Reestablishment of the airway
Adequate oxygenation
Application of positive airway pressure
Via face mask or LMA
Endotracheal intubation with vent support
Although NPPE does not result from fluid overload, most authors recommend gentle diuresis using low-dose furosemide(1mg/kg).

23. Prevention Early recognition Avoid potential obstruction
Ensure adequate depth of anesthesia during use of facemask or LMA
Consider the use of Bite block to ensure patency of artificial airway during emergence from anesthesia
Perform trachial extubation in fully awake Pt.