Paralysis has no effect on chest wall and respiratory system mechanics of mechanically ventilated, sedated patients.
OBJECTIVE
To evaluate the separate effects of sedation and paralysis on chest wall and respiratory system mechanics of mechanically ventilated, critically ill patients.


METHODS
ICU of the University "La Sapienza" Hospital, Rome.


METHODS
13 critically ill patients were enrolled in this study. All were affected by disease involving both lungs and chest wall mechanics (ARDS in 4 patients, closed chest trauma without flail chest in 4 patients, cardiogenic pulmonary oedema with fluidic overload in 5 patients).


RESULTS
Respiratory system and chest wall mechanics were evaluated during constant flow controlled mechanical ventilation in basal conditions (i.e. with the patients under apnoic sedation) and after paralysis with pancuronium bromide. In details, we simultaneously recorded airflow, tracheal pressure, esophageal pressure and tidal volume; with the end-inspiratory and end-expiratory airway occlusion technique we could evaluate respiratory system and chest wall elastance and resistances. Lung mechanics was evaluated by subtracting chest wall from respiratory system data. All data obtained in basal conditions (with the patients sedated with thiopental or propofol) and after muscle paralysis were compared using the Student's t test for paired data. The administration of pancuronium bromide to sedated patients induced a complete muscle paralysis without producing significant modification both to the viscoelastic and to the resistive parameters of chest wall and respiratory system.


CONCLUSIONS
This study demonstrates the lack of additive effects of muscle paralysis in mechanically ventilated, sedated patients. Also in view of the possible side effects of muscle paralysis, our results question the usefulness of generalized administration of neuromuscular blocking drugs in mechanically ventilated patients.
Conti
G
G
Istituto di Anestesia e Rianimazione, Università La Sapienza di Roma, Policlinico Umberto I, Italy.
Vilardi
V
V
Rocco
M
M
DeBlasi
R A
RA
Lappa
A
A
Bufi
M
M
Antonelli
M
M
Gasparetto
A
A
D000328:Adult; D000368:Aged; D016292:Procedural Sedation / Q000379:methods*; D016903:Drug Monitoring; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D003473:Neuromuscular Nondepolarizing Agents / Q000627:therapeutic use*; D010197:Pancuronium / Q000627:therapeutic use*; D015742:Propofol / Q000494:pharmacology*; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000187:drug effects*; D013874:Thiopental / Q000494:pharmacology*; D016896:Treatment Outcome
D006993:Hypnotics and Sedatives; D003473:Neuromuscular Nondepolarizing Agents; D010197:Pancuronium; D013874:Thiopental; D015742:Propofol