Understanding Anesthesiology - The Global Regional Anesthesia ...

Table 15 Dose, onset, duration, elimination, and effects of NDMR
INTUBATING DOSE
(MG/KG)
REPEAT DOSE
(MG/KG)
ONSET
(MIN)
DURATION AFTER
INTUBATING DOSE
(MIN)
METABOLISM/
ELIMINATION
SIDE EFFECTS
PANCURONIUM ROCURONIUM
CIS-
ATRACURIUM
0.08 - 0.1 0.6 - 1 0.15 - 0.25
0.02 0.1 0.02
4-5 1.5 1.5-3
60 - 90 30 - 60 40 - 75
80% renal >70% hepatic
muscarinic
blocker
weak muscarinic
blocker
77% Hoffmann
elimination
none
Contraindications
The major contraindication to the use of any muscle relaxant
is the inability to provide airway and ventilatory
control. A patient who is known or suspected to be a
difficult intubation or a patient who has a fixed airway
obstruction should not receive muscle relaxants prior
to having the airway secured.
Emergence
During the emergence phase of anesthesia, the patient
begins to return to his pre-operative state of consciousness.
In most cases, the anesthesiologist aims to
awaken the patient at the end of the operative procedure
prior to transfer to the post-anesthetic care unit
(PACU). How “awake” must the patient be? Ideally the
patient is conscious enough to obey commands and
support his own airway. At the very least, the patient
must have adequate spontaneous ventilation but may
need minimal assistance to maintain patency of the airway.
In between these two states lies a wide spectrum
of level of consciousness. Patient factors as well as the
anesthetic technique determine the rate at which emergence
from general anesthesia occurs.
Spontaneous and Active Reversal
Emergence requires the offset of effect of the anesthetic
agents. This is achieved by administering the anesthetic
drugs in appropriate doses at the appropriate time according
to the anticipated length of the procedure. The
anesthesiologist relies on the normal metabolism and
excretion of drugs to achieve offset of effect. Active reversal
of drug effect through the administration of another
drug also plays a role in emergence. The most
common example of this is the reversal of muscle relaxation
which is discussed in greater detail below.
Aside from muscle relaxants, anesthetic agents are
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