








































Anesthesia eJournal
Volume 3 Issue 2 2015

AEJ

Educated Hand Publishing LLC 
“The Science Behind the Art”  

 Anesthesia eJournal - Online
ISSN 2333-2611

Postoperative residual neuromuscular blockade continues to affect a considerable percentage of patients admitted to 
the post-anesthesia care unit. Research supports the use of quantitative acceleromyography to monitor neuromuscular 
blockade and recovery. The purpose of this report was to determine whether objective acceleromyography compared 
with subjective peripheral twitch monitors and clinical assessment is more effective in decreasing the occurrence of 
postoperative residual neuromuscular blockade. A literature search was conducted by using ClinicalKey, the Cochrane 
Collaboration, EMBASE, PubMed, and Proquest. A total of 36 articles met the inclusion criteria, of which 8 were 
included in the present review. The evidence is consistent in portraying that the use of acceleromyography does decrease 
the occurrence of residual neuromuscular blockade and it does prevent patients from being reversed at much lower train-
of-four ratios. Residual neuromuscular blockade is too often overlooked and considering its substantial consequences 
should be a reprioritized focus. What remains to be explored is the significance of low-level residual neuromuscular 
blockade postoperatively.

KEYWORDS: neuromuscular blockade monitoring, respiratory, paralysis, complications, acceleromyography, 
postoperative complications, twitch monitor, peripheral nerve stimulator.

Abstract

Neuromuscular Monitoring: Does the Use of Acceleromyography Compared With 
Unaided Clinical Assessment Result in Lower Occurrences of Postoperative Residual 
Neuromuscular Blockade in Patients Admitted to the Post-Anesthesia Care Unit? A 
Literature Review
Becky Flowers, BSN, RRNA

Affiliation:
Texas Christian University, email: rebecca.flowers@tcu.edu

Funding/Conflict of Interest Disclosure: 
None

INTRODUCTION
Postoperative residual neuromuscular blockade continues to affect a considerable percentage of patients admitted to the post-

anesthesia care unit (PACU). Recent evidence suggests that 17% to 36% of patients arriving in the PACU present with objective 
manifestations of incomplete neuromuscular blockade reversal as determined by train-of-four (TOF) ratios less than 0.9.1 Patients 
presenting to the PACU with a TOF ratio <0.9 are considered to have residual neuromuscular blockade and are at increased risk for 
experiencing adverse respiratory events such as reduced upper airway volume, airway obstruction, hypoxemia events, and postoperative 
pulmonary complications.2 Research supports the use of quantitative acceleromyography to monitor neuromuscular blockade and 
recovery. 

Neuromuscular monitoring includes both qualitative monitoring, such as the use of peripheral nerve stimulators and clinical sign 
assessment (eg, 5-s head-lift test and tongue blade stability between the incisors), and quantitative approaches (eg, acceleromyography). 
However, the change in practice from qualitative to quantitative monitoring is accompanied by hesitancy and uncertainty from 
practitioners across the nation who underestimate the occurrence of postoperative residual neuromuscular blockade and its 
consequences. The rationale for switching from qualitative assessments to a more quantitative approach using accelerometry needs 
review. The purpose of this report was to determine whether objective acceleromyography compared with subjective peripheral twitch 
monitors and clinical assessment is more effective in decreasing the occurrence of postoperative residual neuromuscular blockade. 
A literature review of what current research supports and the current trends regarding the impact of qualitative and quantitative 
assessment with respect to residual paralysis is provided, and a synthesis of current research follows. A table of the literature cited will 
be provided as an Appendix for further review. 



Anesthesia eJournal                         www.anesthesiaejournal.com
Volume 3 Issue 2 2015 

METHODOLOGY
A literature search was conducted by using ClinicalKey, The 

Cochrane Collaboration, EMBASE, PubMed, and Proquest. 
Keywords such as “neuromuscular blockade monitoring,” 
“respiratory*,” “paralysis,” “complications,” “postoperative 
residual curarization,” “postoperative complications,” “twitch 
monitor,” and “peripheral nerve stimulator” were used. The 
MESH terms “neuromuscular monitoring” and “respiratory” 
were used for each database search. The key words were also 
used together by using “AND” (“neuromuscular monitoring 
AND respiratory,” “neuromuscular monitoring AND respiratory 
paralysis,” “postoperative complications AND neuromuscular 
monitoring,” “neuromuscular monitoring AND respiratory AND 
twitch monitor,” “neuromuscular monitoring AND respiratory 
postoperative curarization.”) The term OR (“respiratory OR 
paralysis”) was also used. The search was restricted to the years of 
2003 to 2013 and to the specialty of anesthesia. Altogether, the 
databases yielded 336 citations with some overlap. A total of 36 
articles met the inclusion criteria, of which 8 were used for the 
present review. Reference lists of certain studies were searched 
manually and showed much overlap. 

Inclusion criteria were studies of adults (18 years and older), 
patients undergoing surgical procedures, patients admitted 
to the PACU for postoperative monitoring, patients who 
received neuromuscular blocking agents and were given a TOF 
ratio for reversal, and patients who were assessed by either a 
qualitative method or a quantitative method regarding the use of 
acceleromyography. The exclusion criteria were research specific 
to children, animals, emergency operations, or cardiac surgeries; 
review articles; editorials; dissertations; summaries; and foreign 
studies that could not be translated into English. 

Several studies, including the remaining 28 articles found but 
not included here, discussed the correlation of specific agents 
(eg, sugammadex, rocuronium, pancuronium) to the incidence 
of postoperative neuromuscular blockade but did not focus on 
qualitative versus quantitative monitoring or expressed an opinion 
that shifted the focus of the study from scientific evidence to a 
more biased platform. These studies were excluded because they 
were not exclusive to the anesthesia topic.
LITERATURE REVIEW

A meta-analysis was conducted in 2007 to understand the 
impact of neuromuscular monitoring on residual neuromuscular 
blockade.3 Despite previous studies showing an association, the 
use of intraoperative neuromuscular function monitoring was 
not shown to decrease the incidence of postoperative residual 
curarization.3 Since this finding, recent evidence has suggested 
that residual neuromuscular blockade is present not only at TOF 
ratios <0.7 but is becoming more frequent at TOF ratios ≤0.9.4 
Another current study was conducted to determine the incidence 
of residual neuromuscular blockade at the time of extubation. 
When standard criteria (5-s head lift or hand grip, following 
commands, stable ventilatory pattern) were met, tracheal 
extubation was performed.2 Among those individuals undergoing 
elective surgical procedures, 58% had a TOF ratio <0.7 and 
88% had a TOF ratio <0.9 at the time of tracheal extubation.2 
Furthermore, upon arrival to the PACU, general weakness, 5-s eye 

opening and head lift, blurry vision, impaired ability to speak, and 
suppressed ability to cough were present among patients with a 
TOF ratio <0.9 compared with those with a TOF ratio >0.9.2,4 

In another study, objective data obtained by bedside evaluation 
in the PACU did not predict the occurrence of residual 
paralysis when compared with subjective data.5 Murphy et al 
discovered that the “presence or absence of symptoms (difficulty 
swallowing, dysarthria, visual disturbances) of muscle weakness 
was predictive of the presence or absence of a TOF ratio greater 
than 0.90, but the presence or absence of signs (5-second head-
lift test, protrusion of tongue, swallowing ability, opening of 
eyes) of muscle weakness was not.”5(p951) Therefore, bedside 
evaluations are not sensitive enough to confidently rule out 
residual postoperative neuromuscular blockade, which may 
account for the inaccuracy associated with the use of qualitative 
evaluation. If patients are still susceptible to experiencing residual 
paralysis at the current standard (TOF ratio ≥0.9), the use of 
acceleromyography will identify these patients and may reduce 
the occurrence of residual neuromuscular blockade. Perhaps the 
focus for prevention of residual paralysis should not be based on 
the conventional and convenient qualitative method of peripheral 
twitch count but rather on the sensitivity and reliability of 
qualitative versus quantitative evaluation to adequately assess 
TOF ≥ 0.9.

The occurrence of residual paralysis is nondiscriminatory at 
the current benchmark for reversal of a TOF ratio ≥ 0.9. The 
evidence Murphy et al5 present in which clinical tests such as the 
5-s head lift test or handgrip were used to reverse patients at the 
time of tracheal extubation can also be maintained at a TOF ratio 
≤ 0.9. The presentation of postoperative residual neuromuscular 
blockade is associated with a broad window. Residual 
neuromuscular blockade is present and may be symptomatic 
at TOF ratios ≤ 0.9. TOF ratios as low as <0.4 may have TOF 
count fade that is not easily discerned.1 Therefore, it is possible 
that anesthesia practitioners who rely solely on peripheral nerve 
stimulator TOF count may be reversing patients from a deeper 
level of neuromuscular block than assumed by use of subjective 
assessment. Similarly, using TOF count and subjective assessment 
of fade may miss residual neuromuscular blockade postoperatively. 

Capron et al6 conducted a study to determine if the use 
of acceleromyographic TOF ratios could detect residual 
paralysis with 95% probability. The results of this study in 
which patients were randomly assigned to a control group 
or an acceleromyography monitoring group revealed that 
acceleromyography could not detect postoperative residual 
neuromuscular blockade with 95% probability at a TOF ratio less 
than 0.9 but could reliably detect it at TOF ratios equal to 0.95 
and 1.0.6 

Residual neuromuscular blockade is a worldwide problem, yet it 
is incorrectly considered rare by many health care professionals. A 
Portuguese study reported that 91 of 350 patients showed a TOF 
ratio less than 0.9 on arrival in the PACU, giving an incidence of 
residual neuromuscular blockade of 26%.7 This percentage falls 
within the broad gap of 17-36% revealed by previous studies. 
Not only do these data provide congruency of this unfortunate 
percentage, but the study also reported that “there were no 
statistically significant differences in the occurrence of residual 



blockade relating to the neuromuscular blocker used.”7(p3) The 
use of intermediate-acting neuromuscular blockers was thought 
to lower or eliminate the risk of residual paralysis. This is not 
true. The data suggest that the  occurrence of patients being 
admitted to the PACU with residual neuromuscular blockade is 
being under-identified and that reliance on clinical signs alone is 
insufficient to identify all cases of residual paralysis.

A survey conducted among practitioners in the United 
Kingdom revealed that only 28% use peripheral neuromuscular 
monitors, whereas 42% use measurements similar to the 5-s 
head lift test as the diagnostic criteria for extubation.8 A poll 
conducted in the United States showed that only 12% use 
quantitative monitors to assess a patient’s readiness for recovery. 
Of the individuals polled, only 28.8% were correct in selecting 
TOF ratios > 0.9 as the standard for extubation criteria in the 
effort to avoid residual neuromuscular blockade.8

The evidence is consistent in portraying that the use of 
acceleromyography does decrease the occurrence of residual 
neuromuscular blockade and it does prevent patients from being 
reversed at much lower TOF ratios. However, the fact remains 
that postoperative residual neuromuscular blockade can still 
occur at a TOF ≥ 0.9. Acceleromyography has been shown to 
reduce the occurrence of postoperative complications such as 
difficulty maintaining airway patency, yet has not been shown 
to eradicate its occurrence completely. At the current standard, 
acceleromyography is still susceptible to the occasional event 
of postoperative residual neuromuscular blockade, despite the 
lower occurrence than with qualitative assessment. Consequently, 
the current standard is still being accepted for reversal. 
Acceleromyography research has not only been useful in residual 
neuromuscular blockade research but has also contributed to 
the idea that the current TOF ratio is not sufficient for the goal 
of preventing postoperative residual neuromuscular blockade. 
Acceleromyography is useful in regards to outcomes research 
to assess the incidence of postoperative residual neuromuscular 
blockade and the theme that when not used preventable 
complications can arise seems to resonate in the literature. 

Although complications occurring in the PACU are listed, 
problems or events beyond the PACU have not been described in 
great detail. 

The idea that postoperative residual neuromuscular blockade 
results in postoperative morbidity is the current speculation 
in the absence of sufficient scientific data. Sufficient research 
has presented correlations among TOF ratios and clinical 
signs and symptoms and acceleromyography versus qualitative 
data with respect to postoperative residual neuromuscular 
blockade, yet there is no evidence as to how postoperative 
residual neuromuscular blockade impacts patient prognosis 
beyond the immediate period of the postoperative PACU stay. 
Is recovery discharge prolonged as a result of the patient’s 
experiencing postoperative residual neuromuscular blockade? 
Is the experiencing of unexpected complications by the 
patient extraneous to the surgical procedure done as a result of 
experiencing residual neuromuscular blockade in the PACU? 
Data are lacking pertaining to the complications associated with 
low degrees of postoperative residual neuromuscular blockade and 
how it impacts patient prognosis and quality of life in terms of 
days, months, and years. 

The biggest concern is that anesthesia practitioners 
underestimate the occurrence and possibly the severity of 
postoperative residual neuromuscular blockade. Cost analyses 
and outcomes studies with respect to low-level postoperative 
neuromuscular blockade (TOF ratios 0.85 to < 0.95 vs. TOF ≥ 
0.95 or = 1.0) may be the tipping point to change practice from 
subjective peripheral twitch monitoring or clinical assessment 
alone to objective acceleromyographic measurement. 

The answer to the question, Is objective acceleromyography 
compared with subjective peripheral twitch monitoring and 
clinical assessment more effective in decreasing the occurrence 
of postoperative residual neuromuscular blockade? is “yes.” What 
remains to be explored is the significance of low-level residual 
neuromuscular blockade postoperatively. Further investigation is 
warranted and ongoing. 

Anesthesia eJournal                         www.anesthesiaejournal.com
Volume 3 Issue 2 2015

CONCLUSION
Inconsistency in assessment of peripheral twitch monitoring data and the correlation of these data to clinical signs 

allows varying degrees of postoperative residual neuromuscular blockade. If the central focus is to maintain the safety and 
comfort of the patient, the current standard of a TOF ratio ≥ 0.9 should be reevaluated, and acceleromyography must be 
used because peripheral twitch monitors do not provide a TOF ratio but rather only a TOF count. Residual neuromuscular 
blockade is too often overlooked and considering its substantial consequences should be a reprioritized focus. Residual 
neuromuscular blockade is a preventable patient safety problem.3 It is imperative that clinicians be equipped with the 
appropriate tools to adequately assess interventions. The complex nature of residual neuromuscular paralysis will make it 
“difficult to differentiate the adverse physiologic effects resulting from incomplete neuromuscular recovery from the residual 
effects of opioids, benzodiazepines, volatile anesthetics, or anesthesia induction drugs.”9 (p122) Therefore, consideration of 
objective accelerometry use and increasing the standard of “full reversal” to a TOF > 0.95 or = 1.0 needs to be considered. 
From the aspect of patient safety, acceleromyography is a much better tool to use than peripheral twitch monitors and 
certainly unaided clinical assessment. 



Anesthesia eJournal                         www.anesthesiaejournal.com
Volume 3 Issue 2 2015

REFERENCES
1.  Murphy GS, Szokol JW, Marymont JH, et al. Intraoperative acceleromyographic monitoring reduces the result of residual 

neuromuscular blockade and adverse respiratory events in the postanesthesia care unit. Anesthesiology. 2008;109(3):389-398. 
http://dx.doi.org/10.1097/ALN.0b013e318182af3b.

2.  Murphy GS, Szokol JW, Marymont JH, Franklin M, Avram MJ, Vender JS. Residual paralysis at the time of tracheal 
extubation. Anesth Analg. 2005;100(6):1840-1845. http://dx.doi.org/10.1213/01.ANE.0000151159.55655.CB.

3.  Naguib M, Kopman AF, Ensor JE. Neuromuscular monitoring and postoperative residual curarization: a meta-analysis. Br J 
Anaesth. 2007;98(3):302-316. http://dx.doi.org/10.1093/bja/ael386.

4.  Murphy GS, Szokol JW, Avram MJ, et al. Postoperative residual neuromuscular blockade is associated with impaired clinical 
recovery. Anesth Analg. 2013;117(1):133-141. http://dx.doi.org/10.1213/ANE.0b013e3182742e75.

5.  Murphy GS, Szokol JW, Avram MJ, et al. Intraoperative acceleromyography monitoring reduces symptoms of muscle weakness 
and improves quality of recovery in the early postoperative period. Anesthesiology. 2011;115(5):946-954.



Appendix I: Annotated Bibliography Table
Author, 
Date

Study purpose/ 
research ques-
tion

Study Design Theory/ 
Framework 
model

Sample 
& Setting 
Description, 
Size (n)

Data Collection 
Methods

Primary 
Outcome 
Variables

Results Comments

Murphy GS, 
Szokol JW, 
Avram MJ, et al
(2013)a

Determine incidence 
and severity of 
symptoms of muscle 
weakness in patients 
with and without 
residual neuromus-
cular blockade.

Randomized clinical 
trial

None cited 55 patients un-
dergoing elective 
surgical proce-
dures requiring 
neuromuscular 
blockade, with an 
anticipated dura-
tion of at least 60 
minutes

Testing for objective 
evidence of muscle 
weakness (signs) fol-
lowed by an exam-
ination for subjective 
evidence of residual 
paresis (symptoms). 
Each patient was 
assessed for 16 
symptoms and 11 
signs of muscle 
weakness at each 
testing time at arrival 
to PACU, 20 min, 40 
min, & 60 min after.

The incidence of 
symptoms and 
the incidence of 
signs of muscle 
weakness were 
defined as the 
presence of 1 
symptoms or 
signs, respec-
tively, at each 
of the 4 testing 
times in the TOF 
<0.9 and TOF 
>0.9 cohorts.

The incidence and 
severity of muscle 
weakness were 
significantly greater 
in patients with TOF 
ratios <0.9 during 
the first 60 minutes 
of the PACU stay.

Signs of muscle 
weakness were 
observed less 
frequently than 
symptoms. The 
findings from the 
present investiga-
tion demonstrate 
that incomplete 
neuromuscular re-
covery is a primary 
risk factor for un-
pleasant symptoms 
of postoperative 
weakness.

Murphy GS, 
Szokol JW, 
Avram MJ, et al
(2011)b

Acceleromyography 
monitoring would 
diminish unpleas-
ant symptoms of 
residual paresis 
during recovery from 
anesthesia by reduc-
ing the percentage 
of patients with TOF 
<0.9.

Randomized clin-
ical trial to either 
acceleromyography 
(quantitative) or TOF 
(conventional quali-
tative monitoring)

None cited, but 
the design was 
based on the 
findings of Kop-
man et al from a 
study conducted 
in 1997.

155 patients un-
dergoing elective 
surgical proce-
dures requiring 
NMB for at least 
60 min were tele-
phoned the day 
before surgery 
for consent at a 
tertiary medical 
facility

TOF Watch SX was 
placed on patients 
in the OR and was 
randomized to the 
acceleromyography 
or conventional TOF 
group. Ratios and 
evaluation of s/s 
were taken at admit, 
20, 40, 60 min. 

Overall weak-
ness scores, 
total number 
of symptoms 
of muscle 
weakness, total 
number of signs 
of muscle weak-
ness at four time 
intervals during 
the stay in the 
PACU.

TOF ratios in the 
acceleromyography 
group at all time in-
tervals were higher 
and presented with 
fewer symptoms of 
muscle weakness 
in comparison to 
the control group. 
The presence of 
objective s/s was a 
poor determinant of 
PORC compared 
to subjective data 
provided by patient 
surveys.

Although TOF 
ratios <0.9 indicate 
adequate response 
time, subjective 
data presented by 
this study propose 
a new dilemma 
that the degree of 
blockade observed 
is less than what is 
perceived.

Sauer M, 
Stahn A, 
Soltesz S, No-
eldge-Schom-
burg G, & 
Mencke T 
(2011)c

The incidence of 
critical respirato-
ry events, such 
as hypoxemia, in 
patients with minimal 
residual neuromus-
cular blockade and 
comparison of these 
data with those from 
patients with full re-
covery of blockade.

Randomized, 
prospective, place-
bo-controlled trial

None cited; how-
ever, the author 
does cite findings 
from Murphy et 
al reporting a 
high incidence of 
severe residual 
neuromuscular 
blockade- criti-
cal respiratory 
events in patients 
with early POPC 
in the PACU. 
This seems to be 
the basis for this 
study.

132 adult 
patients, aged 
18–80 years, with 
American Society 
of Anesthesiolo-
gy I–III physical 
status, undergo-
ing orthopedic 
surgery under 
general anaes-
thesia, including 
rocuronium to 
produce neuro-
muscular block-
ade; 114 patients 
were randomized 
to one of two 
groups: neostig-
mine group 
(neostigmine) or 
placebo group 
(saline).

PNS and acceler-
omyography were 
used to determine 
TOF ratios. Patients 
were randomized to 
neostigmine (to be 
reversed at ratio > 1) 
or placebo group (to 
be reversed at ratio 
<1). In the PACU 
s/s were assessed 
along with the oc-
currence of adverse 
respiratory events or 
hypoxemia.

s/s of muscle 
weakness and 
the occurrence 
of critical respira-
tory events

Minimal residual 
block was associat-
ed with a higher inci-
dence of hypoxemia 
in the PACU. Critical 
respiratory events, 
such as postoper-
ative respiratory 
insufficiency and 
nonspecific respi-
ratory problems, 
were not observed. 
Among signs and 
symptoms of muscle 
weakness, swal-
lowing difficulties 
occurred more often 
in the patients with 
a minimal residual 
block compared with 
patients with full 
recovery of neuro-
muscular block.

This study is the 
first randomized, 
prospective, 
placebo-controlled 
investigation to 
examine the impact 
of residual neuro-
muscular blockade 
on postoperative 
morbidity. However, 
the evidence does 
not provide new 
insight regarding the 
impact PORC can 
have in postopera-
tive morbidity since 
its study sample 
was restricted to 
neostigmine and 
did not provide ad-
ditional information 
beyond the PACU 
length of stay.

Capron F, Alla 
F, Hottier C, 
Meistelman C, 
Fuchs-Buder T
(2004)d

To determine 
whether the accel-
eromyographic TOF 
ratio detects residual 
paralysis with a 95% 
probability.

Randomized clinical 
trial

None cited; how-
ever, the authors 
utilize evidence 
resulted by Harp-
er et al regarding 
(monitoring) dif-
ferences as the 
basis for the aim 
of the study.

60 adult patients 
undergoing 
elective surgical 
procedures un-
dergoing tracheal 
intubation 

Random selection to 
group A (acceleromy-
ography calibration) 
and group B (non-
calibrated). Negative 
predictive values 
were calculated for 
detecting residual 
paralysis at ratios 
0,9, 0.95, and 1.0. 

Ratio values 
correlating with 
the detection of 
residual paralysis

Acceleromyog-
raphy is unlikely 
to significantly 
improve detection of 
residual paralysis, 
at the TOF of 0.9.  
Increasing TOF 
recovery to 0.95 and 
1.0 increased the 
negative predictive 
values in group A to 
70% and 97%.

Overall, the use of 
acceleromyogra-
phy can impact the 
detection of residual 
paralysis once the 
standard is raised to 
0.95 or 1.0, but cali-
bration prior to NMB 
must be performed.

Murphy GS, 
Szokol JW, 
Marymont JH, 
Franklin M, 
Avram MJ, 
Vender JS
(2005)e

Assess TOF ratios 
immediately before 
tracheal extubation, 
when clinicians had 
determined that full 
recovery of neuro-
muscular function 
had occurred using 
standard clinical 
criteria.

Outcomes study None cited. Since 
“no previous 
studies have 
examined the 
incidence and se-
verity of residual 
neuromuscular 
block at the 
time of tracheal 
extubation,” this 
can be used as 
the foundation of 
this study.

“123 patients 
scheduled for 
elective gyneco-
logic or general 
surgical proce-
dures, between 
the ages of 18 
and 69 yr.”

 

“Standard clinical cri-
teria (5-s head lift or 
hand grip, eye open-
ing on command, 
negative inspiratory 
force, vital capacity 
breath) and peripher-
al nerve stimulation, 
acceleromyography, 
VAS scale”

Presence of 
s/s of residual 
paralysis, TOF 
ratios at time of 
tracheal extuba-
tion, pain per the 
VAS scale during 
stay in PACU.

“Acceptable neuro-
muscular recovery 
(TOF ratio > 0.9) 
was present in only 
a small percentage 
(12%) of patients 
immediately before 
removal of the endo-
tracheal tube.” 58% 
had a TOF ratio 
<0.70 and 88% had 
a TOF ratio <0.90 at 
the time of tracheal 
extubation. Ratios 
were significantly 
lower at the time 
of extubation in 
comparison to stay 
in the PACU.

Acknowledging re-
sidual paralysis can 
occur between TOF 
of 0.70 and 0.90, 
it is appropriate to 
consider changing 
the standard to 
achieve TOF >0.90.

Esteves SO, 
Martins M, 
Barros F, et al 
(2013)f

“Determine the inci-
dence of incomplete 
postoperative neu-
romuscular recovery 
(defined by a TOF 
ratio less than 0.9) 
from anesthesia at 
PACUs in Portu-
guese hospitals.”

Multicenter observa-
tional study

No specific 
framework, but 
“no large-scale 
study about the 
frequency of 
RNMB in Portu-
gal.”

Adult patients 
scheduled for 
elective surgery 
requiring general 
anaesthesia with 
neuromuscular 
blocking agents 
between July 
and November 
2010. A total of 
350 patients were 
used.

Patients who gave 
consent were moni-
tored using the TOF 
Watch SX and were 
categorized into two 
groups according 
to TOF ratios (of at 
least 0.90 and less 
than 0.90).

The presence of 
residual paraly-
sis in PACU and 
corresponding 
TOF ratios.

“Ninety-one patients 
had a train-of-four 
ratio less than 0.9 
on arrival in the pos-
tanaesthesia care 
unit, an incidence of 
residual neuromus-
cular blockade of 
26%.” 

“There were no 
statistically signifi-
cant differences in 
the occurrence of 
RNMB according to 
the neuromuscular 
blocker used.”

Grayling M & 
Sweeney BP 
(2007)g

To determine current 
anesthetic prac-
tice with respect 
to neuromuscular 
monitoring

Prospective survey None cited The questionnaire 
was distributed to 
a total of 715 con-
sultants, trainees, 
and nonconsul-
tant career grades 
anesthetists at 5 
teaching hospitals 
and 7 district 
hospitals in the 
United Kingdom.

“Respondents were 
asked to supply de-
tails regarding their 
use of peripheral 
nerve stimulators in 
the context of neuro-
muscular blockade 
reversal; including 
type of monitor and 
the parameters (i.e., 
train-of-four [TOF] 
ratio) deemed to be 
acceptable for extu-
bation. In addition, 
for those anaesthe-
tists who did not use 
a monitor, informa-
tion was sought 
regarding the clinical 
tests routinely per-
formed at the end of 
surgery.”

Peripheral 
nerve stimulator 
usage, TOF 
ratio standard for 
extubation, other 
“criteria used 
for suitability for 
extubation.”

28% use PNS 
occasionally during 
routine practice, 
62% stated they 
never use it, 74.7% 
stated standard TOF 
ratio for extubation 
is >0.70, 28.8% 
stated standard TOF 
ratio for extubation 
is >0.90. The 5-s 
head lift test was 
used by 42% and 
pattern of respiration 
was used by 36% 
when PNS was not 
used for extubation. 
Finally, 17% state 
neuromuscular mon-
itoring similar to the 
PNS should be used 
in practice.

The survey provides 
a quick glance of 
the consensus 
regarding neuro-
muscular monitoring 
practice; however, it 
would be interesting 
to see how many 
of the respondents 
believe PORC is 
directly impacted 
by the use or ill-use 
of PNS. Overall, it 
does provide the 
reader with an idea 
of how extubation 
criteria are deter-
mined.

Naguib M, 
Kopman AF, 
Ensor JE
(2007)h

Examine the effect 
of intraoperative 
monitoring of neu-
romuscular function 
on the incidence of 
PORC

Meta-analysis Random effects 
model

Data were 
analyzed from 
24 studies (13 
randomized and 
11 observational 
studies). 

Electronic literary 
search of various 
databases (PubMed, 
Cochrane Controlled 
Trials Register, Web 
of Knowledge) from 
1975-2006.

Incidence of 
PORC

“Neuromuscular 
function was moni-
tored in 823 patients 
(24.4%). A simple 
peripheral nerve 
stimulator was used 
in 543 patients, and 
an objective monitor 
was used in 280.” 

“We could not 
demonstrate the 
use of an intraoper-
ative neuromuscular 
function monitor 
decreased the inci-
dence of PORC.”

Abbreviations: NMB, neuromuscular blockade; OR, operating room; PACU, post-anesthesia care unit; PNS, peripheral nerve stimulation; POPC, postoperative pulmonary complication; PORC, postopera-
tive residual curarization; RNMB, residual neuromuscular blockade; s/s, signs and symptoms; TOF, train-of-four. 
aMurphy GS, Szokol JW, Avram MJ, et al. Postoperative residual neuromuscular blockade is associated with impaired clinical recovery. Anesth Analg. 2013;117(1):133-141. http://dx.doi.org/10.1213/
ANE.0b013e3182742e75.
bMurphy GS, Szokol JW, Avram MJ, et al. Intraoperative acceleromyography monitoring reduces symptoms of muscle weakness and improves quality of recovery in the early postoperative period. Anes-
thesiology. 2011;115(5):946-954. http://dx.doi.org/10.1097/ALN.0b013e3182342840.
cSauer M, Stahn A, Soltesz S, Noeldge-Schomburg G, Mencke T. The influence of residual neuromuscular block on the incidence of critical respiratory events. A randomised, prospective, placebo-con-
trolled trial. Eur J Anaesthesiol. 2011;28(12):842-8. doi: 10.1097/EJA.0b013e328345cd11.
dCapron F, Alla F, Hottier C, Meistelman C, Fuchs-Buder T. Can acceleromyography detect low levels of residual paralysis? A probability approach to detect a mechanomyographic train-of-four ratio of 0.9. 
Anesthesiology. 2004;100(5):1119-1124.
eMurphy GS, Szokol JW, Marymont JH, Franklin M, Avram MJ, Vender JS. Residual paralysis at the time of tracheal extubation. Anesth Analg. 2005;100(6):1840-1845. http://dx.doi.org/10.1213/01.
ANE.0000151159.55655.CB.
fEsteves S, Martins M, Barros F, et al. Incidence of postoperative residual neuromuscular blockade in the postanaesthesia care unit: an observational multicentre study in Portugal. Eur J Anaesthesiol. 
2013; 30(5): 243-9. doi: http://dx.doi.org/10.1097/EJA.0b013e32835dccd7.
gGrayling M, Sweeney BP. Recovery from neuromuscular blockade: a survey of practice. Anaesthesia. 2007;62(8):806-809.
hNaguib M, Kopman AF, Ensor JE. Neuromuscular monitoring and postoperative residual curarization: a meta-analysis. Br J Anaesth. 2007;98(3):302-316. http://dx.doi.org/10.1093/bja/ael386.

Anesthesia eJournal                                  www.anesthesiaejournal.com
Volume 3 Issue 2 2015


