I read with great interest the article by Girsberger and colleagues in a recent issue of Anesthesiology.1  The authors investigated 36 patients and concluded that postvoid residuals were significantly lower using ropivacaine compared with bupivacaine for thoracic epidural analgesia reflecting less impairment of detrusor function with ropivacaine. The authors should be congratulated for performing a well-designed randomized trial on an important topic in perioperative medicine. One may argue that by using ropivacaine for thoracic epidurals, the risk of urinary tract infection may be reduced with important consequences for patients and healthcare systems.2,3 

Although the authors performed a well-conducted study, some concerns require clarification to further establish the clinical importance of the study. The authors identified a significant mean difference (95% CI) in postvoid residuals between groups of −175 ml (−295 ml to −40 ml). I wondered why the authors did not measure or report the need for postoperative bladder catheterization, given that this has been more directly related to poor outcomes. It is possible that a large proportion of patients had small postresidual differences and did not require bladder catheterization.4  In addition, I could not determine whether the intraoperative management of these patients was standardized for anesthetics and analgesic agents, given that many of these agents (e.g., opioids, volatile anesthetics) can potentially alter the primary outcome.5,6 

I welcome some clarifications from the authors that could further confirm the validity of this important study.

The author declares no competing interests.

1.
Girsberger
SA
,
Schneider
MP
,
Löffel
LM
,
Burkhard
FC
,
Wuethrich
PY
:
Effect of thoracic epidural ropivacaine versus bupivacaine on lower urinary tract function: A randomized clinical trial.
Anesthesiology
2018
;
128
:
511
9
2.
Maile
MD
,
Armstrong
WF
,
Jewell
ES
,
Engoren
MC
:
Impact of ejection fraction on infectious, renal, and respiratory morbidity for patients undergoing noncardiac surgery.
J Clin Anesth
2017
;
36
:
1
9
3.
Baldini
G
,
Bagry
H
,
Aprikian
A
,
Carli
F
:
Postoperative urinary retention: Anesthetic and perioperative considerations.
Anesthesiology
2009
;
110
:
1139
57
4.
Bjerregaard
LS
,
Hornum
U
,
Troldborg
C
,
Bogoe
S
,
Bagi
P
,
Kehlet
H
:
Postoperative urinary catheterization thresholds of 500 versus 800 ml after fast-track total hip and knee arthroplasty: A randomized, open-label, controlled trial.
Anesthesiology
2016
;
124
:
1256
64
5.
Conner
ER
,
Musser
ED
,
Colpitts
KM
,
Laochamroonvorapongse
DL
,
Koh
JL
:
Perioperative opioid administration in children with and without developmental delay undergoing outpatient dental surgery.
J Clin Anesth
2017
;
37
:
92
6
6.
Howard
J
,
Wigley
J
,
Rosen
G
,
D’mello
J
:
Glycopyrrolate: It’s time to review.
J Clin Anesth
2017
;
36
:
51
3