Speed of Recovery of Reversal of Neuromuscular Blockade in Geriatric Patients Undergoing Spine Surgery

The elderly (age ≥ 65 years) population is the fastest growing segment of the American
population. Spine surgery is one of the most common operative procedures in the United States
and, as the population ages, a larger percentage of geriatric patients will require this
procedure. In addition, spinal surgery is often more complex in the elderly population,
resulting in longer surgical times. A previous study reported that the rate of complex
procedures increased 15-fold in Medicare recipients. Spine surgery is performed in the prone
position and neuromuscular blockade (NMB) is maintained until the patient is returned to the
supine position at the end of surgery to avoid the risk of patient movement, injury, and
inadvertent tracheal extubation while prone. Currently, NMB is reversed with neostigmine
immediately after turning the patients back to the supine position at the end of the
procedure.

Rocuronium bromide, an intermediate-acting neuromuscular blocking agent (NMBA), is used in
approximately 60% of surgical cases in the United States and is commonly used for muscle
relaxation during spinal surgery. With aging, the clearance and half-life of rocuronium is
prolonged resulting in a wide variability in the duration of action and time to reversal.
Until recently, the only medication available for the reversal of neuromuscular blockade was
neostigmine and postoperative residual neuromuscular block (PRNB) was common, especially in
elderly patients. A recent study reported that PRNB occurred in 58% of elderly patients who
were maintained at a moderate level (2 twitches in the TOF) of muscle relaxation with
rocuronium during elective surgery. As a result, these older adults experienced an increased
incidence of airway obstruction, hypoxemic events, muscle weakness, postoperative pulmonary
complications, and increased PACU and hospital lengths of stay.

A new neuromuscular reversal agent sugammadex (Bridion®) has the ability to rapidly reverse
both moderate and deep rocuronium-induced NMB. Another study reported that the mean time to
complete reversal (TOF ratio ≥ 0.9) of a moderate block (2 twitches in the TOF) with
sugammadex in geriatric patients was 2.9 minutes, which was only 1 minute longer than in
younger patients. Reversal of NMB with neostigmine is much slower and it is reported to take
approximately 19 minutes to achieve complete reversal in middle-aged patients. There is
little available data on the NMB reversal time in older adults, but it will likely be even
longer because the age-related physiologic changes prolong neuromuscular recovery. Thus,
sugammadex has the potential to more rapidly reverse NMB in geriatric patients at the end of
surgery. As a result, the use of sugammadex should decrease time in the OR and possibly PACU
time and result in cost savings.

Neostigmine has cardiac muscarinic effects and, therefore, has to be administered with an
anticholinergic agent such as glycopyrrolate to counteract these effects. A previous study
found a 16% incidence of cardiac dysrhythmias in elderly patients who received
neostigmine/glycopyrrolate NMB reversal. The ability of sugammadex to completely reverse NMB
without the addition of an anticholinesterase agent should result in an improved safety
profile in elderly patients.

The goal of this prospective, randomized, double-blinded controlled trial is to test the
hypothesis that the reversal of neuromuscular blockage with sugammadex as compared to
neostigmine in geriatric patients will provide a shorter time to complete recovery of
neuromuscular function, improve the workflow in the operating room and decrease operative
costs.

Inclusion Criteria:

1. Posterior spinal surgery

2. Age ≥ 65 years

3. American Society of Anesthesiologists (ASA) grade I-III

Exclusion Criteria:

1. Inability to obtain written informed consent

2. Allergy to rocuronium or anesthetic agents used in the protocol

3. Known or suspected neuromuscular disorders

4. Significant renal disease with a serum creatinine ≥ 2 mg/dl

5. Significant liver disease

6. A family history of malignant hyperthermia