Incidence and Severity of Residual Neuromuscular Blockade

80 patients will be enrolled in this prospective study. The first 40 patients will serve as
controls and will not have an intervention.

Patients who have surgery and receive general anesthesia often receive muscle relaxants
called neuromuscular blocking drugs or NMBDs. NMBDs facilitate anesthesiologists'
performance of tracheal intubation, provide muscle relaxation during surgery, and are
sometimes administered to prevent movement. After surgery, an anesthesiologist monitors how
the muscle relaxants wear off, and gives a drug to help reverse the effect of the NMBDs
before the tracheal breathing tube is removed and a patient is awakened and taken to the
postoperative care area (PACU).

A patient who receives NMBDs for their routine care can experience a leftover effect of the
drug after their general anesthesia wears off. This condition is called Residual
Neuromuscular Blockade. The management of NMBDs in patients for routine care vary by
anesthesia provider. This study will explore if the use of a specific plan to managing
muscle relaxants will help decrease the risk of muscle weakness after general anesthesia.
Anesthesiologists routinely use peripheral nerve stimulators to assess the degree of muscle
relaxation. Very commonly a series of 4 electrical stimulations are given over 2 seconds and
each stimulation result in a twitch of the thumb when the ulnar nerve is stimulated at the
wrist. This is called train-of-four (TOF) monitoring. When the patient is deeply relaxed,
then all twitches are not present but as the drug effect diminishes over time, the twitches
return. When 4 twitches are present, an exact measurement of the so-called TOF ratio can be
calculated if an objective monitor is used. The ratio is the strength of the fourth twitch
divided by the strength of the first twitch. The most commonly used reversal drug is
neostigmine and it is known from previous research that it works more effectively if the
muscle relaxation is not profound. In the intervention group, the investigators will confirm
that the neuromuscular blockade has spontaneously recovered to a level where all 4 thumb
twitches are present before neostigmine is administered.

All patients will have objective measurements obtained using the FDA approved monitor
TOF-Watch SX. This monitor will be applied at the beginning of each case and will be
calibrated immediately after induction of anesthesia. This is a simple automated process
that takes less than 1 minute. The investigators will also obtain a TOF ratio measurement at
the beginning of the case, before a muscle relaxant has been administered. This initial
measurement allows for normalization of postoperative measurements. Measurement will be
obtained again at the time of extubation, i.e. the removal of the breathing tube, which
usually occurs in the operating room as the patient is awakened after surgery. Patients are
routinely transferred to the post-anesthesia care unit (PACU) within minutes of being
extubated and shortly after arrival to the PACU, the anesthesiologists transfers the care to
PACU RNs. The investigators will obtain one more TOF-ratio measurement when the patient has
just arrived to the post-anesthesia care unit (PACU).

Inclusion Criteria:

- Adults age 18 or older

- Will undergo open or laparoscopic abdominal surgery expected to last <4 hours at HMC
or UWMC

- Have ASA physical status I-III

- Scheduled to have general anesthesia with at least 1 dose of nondepolarizing NMBD for
endotracheal intubation or maintenance of neuromuscular block (NMB)

Exclusion Criteria:

- Allergy to NMBDs

- Patients with neuromuscular disease (myasthenia gravis or muscular dystrophy)

- Pregnant or lactating women

- Non-English speaking

- Unable to provide informed consent