Post-operative residual paralysis is common.pearl
- Bertrand Debaene, Benoît Plaud, Marie-Pierre Dilly, and François Donati.
- Department of Anesthesia and Intensive Care, Hôpital Jean Bernard, Poitiers, France. email@example.com
- Anesthesiology. 2003 May 1;98(5):1042-8.
BackgroundResidual neuromuscular blockade remains a problem even after short surgical procedures. The train-of-four (TOF) ratio at the adductor pollicis required to avoid residual paralysis is now considered to be at least 0.9. The incidence of residual paralysis using this new threshold is not known, especially after a single intubating dose of intermediate-duration nondepolarizing relaxant. Therefore, the aim of the study was to determine the incidence of residual paralysis in the postanesthesia care unit after a single intubating dose of twice the ED(95) of a nondepolarizing muscle relaxant with an intermediate duration of action.MethodsFive hundred twenty-six patients were enrolled. They received a single dose of vecuronium, rocuronium, or atracurium to facilitate tracheal intubation and received no more relaxant thereafter. Neuromuscular blockade was not reversed at the end of the procedure. On arrival in the postanesthesia care unit, the TOF ratio was measured at the adductor pollicis, using acceleromyography. Head lift, tongue depressor test, and manual assessment of TOF and DBS fade were also performed. The time delay between the injection of muscle relaxant and quantitative measurement of neuromuscular blockade was calculated from computerized anesthetic records.ResultsThe TOF ratios less than 0.7 and 0.9 were observed in 16% and 45% of the patients, respectively. Two hundred thirty-nine patients were tested 2 h or more after the administration of the muscle relaxant. Ten percent of these patients had a TOF ratio less than 0.7, and 37% had a TOF ratio less than 0.9. Clinical tests (head lift and tongue depressor) and manual assessment of fade showed a poor sensitivity (11-14%) to detect residual blockade (TOF < 0.9).ConclusionAfter a single dose of intermediate-duration muscle relaxant and no reversal, residual paralysis is common, even more than 2 h after the administration of muscle relaxant. Quantitative measurement of neuromuscular transmission is the only recommended method to diagnose residual block.
This article appears in the collection: Neuromuscular myths: the lies we tell ourselves.
Debaene et al. investigated residual paralysis in the PACU after a single intubating dose of intermediate NMBD in the absence of reversal.
They identified PORC (Post-Operative Residual Curarization = TOFR <0.9) in 45% of patients, with 'time since NMBD' ranging from 30 to 400 minutes.
In a subgroup of patients 2 hours after a single NMBD dose there was still a 37% incidence of PORC.
Additionally there was very wide inter-patient variability, with PORC persisting more than 6 hours in three patients, and several patients with TOFR of only 0.2 after 2 hours.
The 5-second Head Lift Test and the Tongue Depressor Test, often used to detect PORC in the PACU are of limited use for detecting TOFR < 0.9, having sensitivities of only 11% and 13% and specificities of 87% and 90% respectively.
The Head Lift Test cannot identify POCR with a TOFR > 0.5. Debaene’s study population demonstrated Positive and Negative Predictive Values of the Head Lift and Tongue Depressor Tests of only 53-58%!
Subjective, qualitative neuromuscular monitors fare no better: Tactile TOF Fade and Double Burst Stimulation (DBS) have similar sensitivities (11% and 13% respectively), although high specificities (99% each). This provides a good Positive Predictive Value (93% & 97%) but a very poor Negative Predictive Value (57% & 58%) (depending on the incidence of PORC).