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REPORTS OF ORIGINAL INVESTIGATIONS
Time to recovery after general anesthesia at hospitals
with and without a phase I post-anesthesia care unit: a historical
cohort study
De
´lai de re
´cupe
´ration apre
`s une anesthe
´sie ge
´ne
´rale dans les
ho
ˆpitaux disposant d’une unite
´de soins postanesthe
´siques de
phase I par rapport a
`des ho
ˆpitaux n’en disposant pas : une e
´tude
de cohorte historique
Kokila N. Thenuwara, MD, MBBS, MME, MHCDS .Tatsuya Yoshimura, MD, MBA .
Yoshinori Nakata, MD, MBA .Franklin Dexter, MD, PhD, FASA
Received: 9 April 2018 / Revised: 30 May 2018 / Accepted: 31 May 2018 / Published online: 12 September 2018
ÓCanadian Anesthesiologists’ Society 2018
Abstract
Purpose There is little knowledge about how hospitals can
best handle disruptions that reduce post-anesthesia care
unit (PACU) capacity. Few hospitals in Japan have any
PACU beds and instead have the anesthesiologists recover
their patients in the operating room. We compared
postoperative recovery times between a hospital with
(University of Iowa) and without (Shin-yurigaoka
General Hospital) a PACU.
Methods This historical cohort study included 16
successive patients undergoing laparoscopic gynecologic
surgery with endotracheal intubation for general
anesthesia, at each of the hospitals, and with the hours
from OR entrance until the last surgical dressing applied
Ctwo hours. Postoperative recovery times, defined as the
end of surgery until leaving for the surgical ward, were
compared between the hospitals.
Results The median [interquartile range] of recovery
times was 112 [94-140] min at the University of Iowa
and 22 [18-29] min at the Shin-yurigaoka General
Hospital. Every studied patient at the University of Iowa
had a longer recovery time than every such patient at Shin-
yurigaoka General Hospital (Wilcoxon-Mann-Whitney, P
\0.001). The ratio of the mean recovery times was 4.90
(95% confidence interval [CI], 4.05 to 5.91; P \0.001)
and remained comparable after controlling for surgical
duration (5.33; 95% CI, 3.66 to 7.76; P \0.001). The
anesthetics used in the Iowa hospital were a volatile agent,
hydromorphone, ketorolac, and neostigmine compared
with the Japanese hospital where bispectral index
monitoring and target-controlled infusions of propofol,
remifentanil, acetaminophen, and sugammadex were used.
Conclusions This knowledge can be generally applied
in situations at hospitals with regular PACU use when
there are such large disruptions to PACU capacity that it is
known before a case begins that the anesthesiologist likely
will need to recover the patient (i.e., when there will not be
an available PACU bed and/or nurse). The Japanese
anesthesiologists have no PACU labour costs but likely
greater anesthesia drug/monitor costs.
Re
´sume
´
Objectif Nous savons peu de choses sur la fac¸on dont les
ho
ˆpitaux peuvent le mieux re´soudre les perturbations qui
Drs. Thenuwara and Yoshimura contributed equally to this research.
K. N. Thenuwara, MD, MBBS, MME, MHCDS
Department of Anesthesia, University of Iowa, Iowa City, IA,
USA
T. Yoshimura, MD, MBA
Department of Anesthesia, Shin-yurigaoka General Hospital,
Kawasaki, Kanagawa, Japan
Y. Nakata, MD, MBA
Teikyo University, Tokyo, Japan
F. Dexter, MD, PhD, FASA (&)
Division of Management Consulting, Department of Anesthesia,
University of Iowa, 200 Hawkins Drive, 6-JCP, Iowa City, IA
52242, USA
e-mail: Franklin-Dexter@UIowa.edu
URL: https://www.FranklinDexter.net
123
Can J Anesth/J Can Anesth (2018) 65:1296–1302
https://doi.org/10.1007/s12630-018-1220-1
re´duisent la capacite´ des unite´s de soins postanesthe´sie
(salle de re´veil). Au Japon, peu d’ho
ˆpitaux disposent de lits
de salle de re´veil et les anesthe´siologistes laissent les
patients re´cupe´rer dans la salle d’ope´ration. Nous avons
compare´lede´lai de re´cupe´ration postope´ratoire entre un
ho
ˆpital disposant d’une salle de re´veil (Universite´de
l’Iowa) et un ho
ˆpital n’en ayant pas (Ho
ˆpital ge´ne´ral Shin-
yurigaoka).
Me
´thodes Cette cohorte historique a inclus 16 patientes
successives subissant une chirurgie gyne´cologique par voie
laparoscopique avec intubation endotrache´ale et
anesthe´sie ge´ne´rale dans chacun des ho
ˆpitaux lorsque le
de´ lai entre l’entre´e au bloc ope´ratoire et le dernier
pansement chirurgical mis e´tait C2 heures. Le temps de
re´ cupe´ration postope´ ratoire, de´fini comme e´ tant le de´lai
e´ coule´ entre la fin de l’intervention et le de´part pour l’unite´
de chirurgie a e´te´ compare´ entre les 2 ho
ˆpitaux.
Re
´sultats La valeur me´diane [plage interquartile] du
temps de re´cupe´ration a e´te´ de 112 [94-140] minutes a`
l’universite´ de l’Iowa et de 22 [18-29] minutes a` l’ho
ˆpital
ge´ne´ral Shin-yurigaoka. Toutes les patientes e´tudie´es a`
l’universite´ de l’Iowa ont eu un temps de re´cupe´ration plus
long que chacune des patientes de l’ho
ˆpital ge´ne´ral Shin-
yurigaoka (test de Wilcoxon-Mann-Whitney, P \0,001). Le
rapport des temps moyens de re´cupe´ration a e´te´ de 4,90
(intervalle de confiance [IC] a` 95 % : 4,05 a` 5,91; P \
0,001) et est reste´ comparable apre`s contro
ˆle pour la dure´e
de l’intervention (5,33; IC a` 95 %, 3,66 a` 7,76;
P\0,001). Les agents anesthe´siques utilise´s a` l’ho
ˆpital
de l’Iowa e´taient un agent volatil, l’hydromorphone, le
ke´ torolac et la ne´ostigmine alors que dans l’ho
ˆpital
japonais le monitorage de l’indice bispectral et des
perfusions contro
ˆle´ es avec cible de propofol et de
re´ mifentanil, de l’ace´taminophe`ne et du sugammadex ont
e´te´ utilise´s.
Conclusions Ces connaissances peuvent eˆtre applique´es
plus ge´ne´ralement aux ho
ˆpitaux disposant de salles de
re´ veil quand on sait a` l’avance que l’anesthe´siologiste
aura probablement besoin de laisser re´cupe´rer le patient
en salle d’ope´ration a` cause de perturbations importantes
des capacite´s de la salle de re´veil (c’est-a`-dire, absence de
lit et/ou d’infirmie`re disponible). Les anesthe´siologistes
japonais n’engendrent pas de frais de personnel en salle de
re´ veil, mais occasionnent probablement des frais plus
e´ leve´s de monitorage et de me´ dicaments anesthe´siques.
Sento et al. recently published their survey of hospitals in
Japan finding that only 16% have any phase I
postanesthesia care unit (PACU) beds.
1
The phase I
discharge-to-ward PACU is differentiated from the
discharge-to-home phase II PACU of outpatient surgical
departments.,
2,A
In Japan, patients are recovered in the
operating room (OR) by the anesthesiologist and then go
directly to the hospital ward. This occurs despite Japanese
hospitals often having a higher postoperative patient-to-
nurse ratio than in the USA (i.e., it is not because the
Japanese wards are functioning like PACUs).
B
Potentially,
in Japan, more expensive devices and drugs are being used,
facilitating fast recovery in the OR, while in the USA
expensive PACU nurse labour is being used instead. We
therefore speculate that there may be useful insights from
the anesthesia techniques used in Japanese hospitals that
recover patients exclusively in their ORs. Anesthesiologists
working at hospitals with regular PACUs can use the
insights when expected to recover the patient (i.e., the
PACU is anticipated to be full).
In this historical cohort study, we compared the surgical
recovery times between the University of Iowa hospital in
Iowa City and the Shin-yurigaoka General Hospital near
Tokyo. Our objective was to test the hypothesis that the
times from end of surgery until the patients left for the
surgical ward (i.e., ‘‘recovery times’’) would be much
longer at the University of Iowa with a PACU compared
with a Tokyo hospital that does not use a PACU.
Methods
The Institutional Review Boards (IRB) of the University of
Iowa (201801768; 25 January 2018) and of Shin-yurigaoka
General Hospital (20180219-1; 20 February 2018)
approved this historical cohort study and considered it
exempt from the requirement of obtaining written consent
of patients.
The population studied was patients undergoing
laparoscopic gynecologic surgery. We chose this
population because it was the one category with many
patients at both the investigators’ hospitals. No restriction
was placed on whether the patient leaving the PACU
(University of Iowa) or OR (Shin-yurigaoka General
Hospital) was going to a hospital ward or to a phase II
PACU location (see footnote A in the introduction). All
successive patients were studied that met the following
inclusion criteria: i) a laparoscopic gynecologic procedure
was scheduled and performed for at least part of the
A
For the current paper, we consider patients discharged to ward.
Generally, patients may be discharged from the phase I
postanesthesia care unit (PACU) to the phase II PACU, a ward, or
intensive care unit.
B
As reported by the Chief gynecologic nurse, each ward nurse at
Shin-yurigaoka General Hospital cares for an average of seven
gynecologic patients, more than the five or six at the University of
Iowa.
123
Recovery times after anesthesia without PACU 1297
surgical case (i.e., it could have been completed with
laparotomy); ii) endotracheal intubation for general
anesthesia was done; iii) actual hours from OR entrance
until the last surgical dressing was placed on the patient
was Ctwo hours.
Patients were selected in reverse sequence from 31
December 2017. Electronic chart review was performed for
16 successive patients (see the power analysis below). The
requirement was placed on the protocol design that the
study would be reevaluated if 16 such patients were not
identified who had undergone surgery within six months
(i.e., all patients studied had surgery between 1 July 2017
and 31 December 2017). The dates were otherwise not
recorded; only times were recorded, in accordance with the
IRB protocol. This was because as the specific hospitals
were being identified, the combination of procedure
(inherently specifying sex) and date potentially could
lead to identification of the patients.
3,4
The primary endpoint of this study was the ‘‘recovery
time,’’ defined as the time from end of surgery (i.e., final
wound covered)
5
until the patient left for the hospital ward.
If there were differences in recovery times, the anesthetic
monitors and drugs used would be of interest and were
therefore also recorded.
Statistical methods
The primary method of statistical analysis was chosen a
priori. The Wilcoxon-Mann-Whitney test was used to
estimate the probability (p00) that a randomly selected case
at the University of Iowa had a longer time to recovery than
did a randomly selected case at the Shin-yurigaoka General
Hospital.
The secondary methods of analysis used generalized
linear modeling, a log link function, and heteroscedastic-
robust standard error. This analysis was performed while
controlling for covariates, including the time from OR
entrance to end of surgery. We expected this variable to be
a significant covariate that could cause bias because of its
positive correlation among all types of procedures with the
time from end of surgery to extubation.
6
The following power analysis, as reported to the IRBs,
was used to determine the sample size. Because of the
multiple planned analyses, a type I two-sided error rate
(alpha) of 0.01 was used: Z
alpha/2
=Z
0.005
= 2.58. In
addition, a 90% statistical power to detect a difference
between hospitals was planned: Z
beta
=Z
0.10
= 1.28.
Assuming equal sample sizes at each of the two hospitals,
equation A3.2 in Divine et al. was applied to our problem
7
;
accordingly, each group’s N= 2.48/(p00 -0.5)
2
. From
preliminary discussions about respective patients’ typical
recovery times, we expected no overlap of recovery time
between the US and Japanese hospitals, but also recognized
that there may be some overlap due to uncommon patient
or operational conditions. We used p00 = 0.90 (i.e., at most
10% overlap between groups) and thus obtained data on 16
consecutive patients meeting the inclusion criteria at each
hospital.
Results
All 16 of the patients at the Shin-yurigaoka General
Hospital Tokyo went to the hospital ward directly from the
OR. None of the 16 University of Iowa patients needed to
wait in the PACU because a ward bed was unavailable (i.e.,
none of the measured recovery times was prolonged for
such non-clinical reasons). All the data elements recorded
about each patient are listed in Table 1along with the
summary measures.
The median [interquartile range] of recovery times was
112 [94-140] min at the University of Iowa and 22 [18-29]
min at the Shin-yurigaoka General Hospital (Figure). Every
studied patient at the University of Iowa had a longer
recovery time than every such patient at Shin-yurigaoka
General Hospital (Wilcoxon-Mann-Whitney, P\0.001)
(Figure). The ratio of the mean recovery times was 4.90
(95% confidence interval [CI], 4.05 to 5.91; P\0.001),
which remained comparable while controlling for the
duration of surgery (5.33; 95% CI, 3.66 to 7.76; P\
0.001). Thus, the estimated mean recovery time at Shin-
yurigaoka General Hospital was approximately 80% [i.e., 1
-(1/4.90) = 79.6% and 1 -(1/5.33) = 81.2%] faster than
that of the University of Iowa Hospital.
Covariates that could not be studied were those that
differed uniformly between the hospitals (Table 1). None
of the patients at the University of Iowa had BIS
TM
(Medtronic; Minneapolis, MN, USA) monitoring vs all the
patients at Shin-yurigaoka General Hospital. In addition,
all the patients at the University of Iowa had anesthetic
maintenance with a volatile agent, whereas all the patients
at Shin-yurigaoka General Hospital received target-
controlled infusions of propofol. Analgesics, in addition
to fentanyl, were hydromorphone and/or ketorolac at the
University of Iowa compared with remifentanil and
acetaminophen at Shin-yurigaoka General Hospital.
Reversal of neuromuscular blockade was done with
neostigmine at the University of Iowa vs sugammadex at
Shin-yurigaoka General Hospital.
Discussion
At a Japanese hospital with no PACU, where
anesthesiologists recover their patients in the OR, mean
recovery times after general anesthesia for laparoscopic
123
1298 K. N. Thenuwara et al.
Table 1 Comparisons of patients and anesthetics at University of Iowa and Shin-yurigaoka General Hospital in Tokyo
Variable University of Iowa Shin-yurigaoka General Hospital
(Tokyo)
Pvalue
BIS monitor Used 0
Not used 16
Used 16
Not used 0
\0.001
Maintenance hypnotic Propofol target- controlled infusion
0
Sevoflurane 9
Isoflurane 6
Desflurane 1
Propofol target-controlled infusion 16
Sevoflurane 0
Isoflurane 0
Desflurane 0
\0.001
Additional analgesics Remifentanil and acetaminophen 0
Hydromorphone and ketorolac 7
Hydromorphone 7
Ketorolac 2
None 0
Remifentanil and acetaminophen 15
Hydromorphone and ketorolac 0
Hydromorphone 0
Ketorolac 0
None 1
\0.001
Reversal of neuromuscular blockade Sugammadex 0
Neostigmine 14
None 2
Sugammadex 15
Neostigmine 1
None 0
\0.001
Time from OR entrance to end of surgery (hr) Median 4.72
25th percentile 4.02
75th percentile 5.51
Mean 4.91
Median 2.70
25th percentile 2.39
75th percentile 3.41
Mean 2.99
0.001
Procedure Hysterectomy 13
Myomectomy 1
Cystectomy 0
Sacral colpopexy 2
Hysterectomy 7
Myomectomy 6
Cystectomy 3
Sacral colpopexy 0
0.011
Decade of age (years) Median 45
25th percentile 40
75th percentile 55
Median 40
25th percentile 30
75th percentile 45
0.35
Time from end of surgery to tracheal extubation (min) Median 11.0
25th percentile 7.5
75th percentile 19.5
Mean 13.9
Median 9.0
25th percentile 6.5
75th percentile 11.0
Mean 8.9
0.36
ASA physical status 1-2 13
33
1-2 16
30
0.23
Fentanyl before tracheal extubation Used 14
Not used 2
Used 16
Not used 0
0.48
Time of day of end of surgery Median 3:05 PM
25th percentile 12:22 PM
75th percentile 5:16 PM
Median 3:52 PM
25th percentile 1:38 PM
75th percentile 4:44 PM
0.55
Another case performed in the OR after the current
case
Yes 10
No 6
Yes 9
No 7
0.99
Another case performed in the OR after the current
case and by the same surgeon
Yes 9
No 7
Yes 8
No 8
0.99
Rocuronium Used 16
Not used 0
Used 16
Not used 0
1.00
Elective procedure Elective 16
Urgent 0
Elective 16
Urgent 0
1.00
Categories were compared using Fisher’s exact test. Continuous and ordered variables were compared using the Wilcoxon-Mann-Whitney test.
Pvalues are two-sided. ASA = American Society of Anesthesiologists; OR = operating room
At the University of Iowa, propofol was used for induction and not maintenance, and none of the analgesics was infused
123
Recovery times after anesthesia without PACU 1299
gynecologic surgery were 80% faster than those of a US
hospital that uses a PACU.
Our results have economic implications. An anesthetic
with BIS monitoring, propofol target-controlled infusion,
remifentanil, acetaminophen, and sugammadex will have a
greater device and drug cost than one with sevoflurane,
hydromorphone, ketorolac, and neostigmine. Nevertheless,
if an anesthesiologist is going to recover the patient 1:1
rather than a nurse caring for two patients in a PACU
2
(with anesthesiologist backup), the labour costs per hour
will be greater.
8,9
Thus, the Japanese anesthesiologists
substitute more expensive supplies/drug costs for less of
their time (i.e., labour costs). The approach of using the
BIS monitor and drugs with fast recovery time is sustained,
in part, by the Japanese’ Diagnostic Procedure
Combination hospital payment system that excludes
anesthesia drugs, making them fee-for-service, paid by
the patient’s insurance; thus, the hospital lacks incentive
for lesser cost. This approach not to reduce the time spent
in the PACU but to facilitate its bypass altogether matches
the findings of the pharmacoeconomics of anesthetic drugs
and techniques for outpatient surgery.
10-12
For outpatient
surgery, this strategy lowers costs especially for facilities
with many patients per day, an eight-hour (vs a longer ten-
hour) OR workday, and PACU nurses who either are
salaried or work full-time hourly and frequently have
overtime.
13,14
Our results are potentially useful at hospitals with
regular PACU use when it is known before a case begins
that the anesthesiologist likely will need to recover the
patient in the OR (i.e., there will not be an available PACU
bed and/or nurse). An example of such events is when there
is damage to portions of the PACU (e.g., flooding).
15
Other
situations where this event might occur include when
patients from another location (e.g., non-OR anesthetizing
locations) are being recovered temporarily in the surgical
PACU (e.g., the other location’s PACU is temporarily
closed for renovations). Nevertheless, our findings that
different anesthetics can, in combination, result in recovery
times that are only 20% as long were for gynecologic
surgery (Table 2). Knowing before the case begins that the
patient has a substantial chance of needing recovery in the
OR generally would depend on there being PACU staffing
shifts and start times chosen based on matching the
expected peak number of PACU patients by time of
day.
16-20
Even then, when there is a large variability among
days in the peak numbers of patients, predicting for the
individual case is challenging.
21
Nevertheless, this is not so
when a disruption is so large that there will inevitably be
cases every day with recovery in the OR.
15
For example, if
a 12-bed PACU only has eight beds available for surgical
patients for a week (e.g., from renovation), and the other
patients recover in the ORs, there will be negligible
variability in the peak number of patients in the PACU
(i.e., it will be eight patients for most of the workday).
Planning can be done in this circumstance.
22
Study limitations
We did not collect safety data and do not have the timing
on when each patient met each of the multiple criteria for
Figure Recovery time at the University of Iowa and at Shin-
yurigaoka General Hospital after general anesthesia for laparoscopic
gynecologic surgery. The recovery time was the time from final
wound covering until the patient left for the hospital ward. A potential
independent variable that differed between hospitals was the time
from operating room (OR) entrance to the final dressing on the patient
(Tables 1and 2)
Table 2 Ratio of mean recovery times between University of Iowa and Shin-yurigaoka General Hospital in Tokyo
Variable from Table 1that differs significantly but not completely
between hospitals
Mean (95% confidence
interval)
Pvalue for ratio
of recovery times
Pvalue for
covariate
None 4.90 (4.05 to 5.91) \0.001
Time from OR entrance to end of surgery 5.33 (3.66 to 7.76) \0.001 0.49
Hysterectomy 4.92 (4.11 to 5.90) \0.001 0.91
Recovery time was measured as the period from end of surgery until the patient was ready to leave for the hospital ward. The non-significant
effect of surgical time had a narrow confidence interval, with a 0.997 to 1.001-fold longer recovery time for each additional one minute of
surgical time (i.e., 0.9995 to 1.0000 per hour). The generalized linear modeling also was performed using the sequence of the patients at each
hospital as a continuous variable: 4.89 (4.10 to 5.83), P\0.0001, and sequence P= 0.15. OR = operating room
123
1300 K. N. Thenuwara et al.
discharge to the ward.
C,23
However, the hospital in Tokyo
does not have a PACU for any of its patients (i.e., it was
not just unavailable for the study patients); only 16% of
hospitals in Japan have any PACU beds.
1
Thus, the
relevant issue is not whether patients can safely undergo
surgery and then go directly to a hospital ward with no
greater numbers of nurses there than in North America. The
question is how long patients routinely wait in the ORs
recovering. The answer is vastly less time (20%) than that
spent routinely in a phase I PACU. Nevertheless, while
achieving this reduction in labour costs, the anesthetics
were different and generally more expensive (i.e.,
substitution of drug/supply for labour costs). As referred
to in the last paragraph of the results, from the data, we are
unable to know which of the differences in drugs/supplies
contribute to the briefer recovery times. We also cannot
quantify whether recovery time is saved by not having a
handoff of care or from heterogeneity in the use of
discharge criteria.
C
We limited the procedure category to laparoscopic
gynecologic surgery, though this was unlikely to have
influenced our conclusions. The principal covariates for
recovery time after general anesthesia are not surgical
procedure or patient sex, but availability of
anesthesiologists, transport personnel, or ward beds, as
well as patient pain.
24,25
We did not have a way to collect patients’ initial
postoperative pain scores, because the data were collected
retrospectively. However, it is unlikely that differences in
acute pain during the first couple of hours after surgery
account for the 4.9-fold differences in recovery times.
However, our conclusions are limited to the fact that the
recovery times differ markedly between hospitals; we do
not have a way to know how the differences were achieved.
The application of our study was in the consideration of
using different anesthetic techniques to reduce recovery
times when the PACU is full. An alternative strategy may
be to revise case sequencing to reduce the peak necessary
number of PACU nurses and beds.
26
When there are
sufficient nurses and beds to prevent delays from the OR
into the PACU, case sequencing does not significantly
reduce the necessary PACU nursing hours.
27
Nevertheless,
that may not be so under the conditions in the present
study. This would not change the results of our study about
recovery times, but would reduce their usefulness, since if
it were known ahead which patients likely will recovery in
the ORs, the less expensive intervention would be case
sequencing rather than using more expensive anesthetic
drugs and supplies.
Conflicts of interest The Division of Management Consulting,
Department of Anesthesia, University of Iowa, performs some of the
calculations described in this article. Franklin Dexter receives no
funds personally other than his salary and allowable expense
reimbursements from the University of Iowa and has tenure with no
incentive program. He and his family have no financial holdings in
any company related to his work other than indirectly through mutual
funds for retirement. Income from the Division’s consulting work is
used to fund Division research.
Editorial responsibility This submission was handled by Dr.
Hilary P. Grocott, Editor-in-Chief, Canadian Journal of Anesthesia.
Author contributions Kokila N. Thenuwara and Tatsuya
Yoshimura helped design and conduct the study. Yoshinori Nakata
helped design the study. Franklin Dexter helped design and conduct
the study, analyze the data, and write the manuscript.
Funding Departmental funding.
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C
At the University of Iowa, the postanesthesia care unit (PACU)
discharge policy has three criteria in addition to those of the modified
Aldrete score:
23
normothermia, no indication of urinary retention or
oliguria, and a minimum PACU time of 30 min. The latter had no
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