Anesthesiology 2002; 96:795– 802 © 2002 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.
Effects of Recruiting Maneuvers in Patients with Acute
Respiratory Distress Syndrome Ventilated with Protective
Ventilatory Strategy
Salvatore Grasso, M.D.,* Luciana Mascia, M.D.,† Monica Del Turco, M.D.,‡ Paolo Malacarne, M.D.,‡
Francesco Giunta, M.D.,§ Laurent Brochard, M.D., Arthur S. Slutsky, M.D.,# V. Marco Ranieri, M.D.**
Background: A lung-protective ventilatory strategy with low
tidal volume (V
T
) has been proposed for use in acute respiratory
distress syndrome (ARDS). Alveolar derecruitment may occur
during the use of a lung-protective ventilatory strategy and may
be prevented by recruiting maneuvers. This study examined the
hypothesis that the effectiveness of a recruiting maneuver to
improve oxygenation in patients with ARDS would be influ-
enced by the elastic properties of the lung and chest wall.
Methods: Twenty-two patients with ARDS were studied during
use of the ARDSNet lung-protective ventilatory strategy: V
T
was
set at 6 ml/kg predicted body weight and positive end-expira-
tory pressure (PEEP) and inspiratory oxygen fraction (FIO
2
)
were set to obtain an arterial oxygen saturation of 90 –95%
and/or an arterial oxygen partial pressure (PaO
2
) of 60–
80 mmHg (baseline). Measurements of PaO
2
/FIO
2
, static volume–
pressure curve, recruited volume (vertical shift of the volume-
pressure curve), and chest wall and lung elastance (Est
W
and
Est
L
: esophageal pressure) were obtained on zero end-expira-
tory pressure, at baseline, and at 2 and 20 min after application
of a recruiting maneuver (40 cm H
2
O of continuous positive
airway pressure for 40 s). Cardiac output (transesophageal
Doppler) and mean arterial pressure were measured immedi-
ately before, during, and immediately after the recruiting ma-
neuver. Patients were classified a priori as responders and
nonresponders on the basis of the occurrence or nonoccur-
rence of a 50% increase in PaO
2
/FIO
2
after the recruiting
maneuver.
Results: Recruiting maneuvers increased PaO
2
/FIO
2
by 20
3% in nonresponders (n 11) and by 175 23% (n 11;
mean standard deviation) in responders. On zero end-expi-
ratory pressure, Est
L
(28.4 2.2 vs. 24.2 2.9 cm H
2
O/l) and
Est
W
(10.4 1.8 vs. 5.6 0.8 cm H
2
O/l) were higher in nonre-
sponders than in responders (P < 0.01). Nonresponders had
been ventilated for a longer period of time than responders
(7 1 vs. 1 0.3 days; P < 0.001). Cardiac output and mean
arterial pressure decreased by 31 2 and 19 3% in nonre-
sponders and by 2 1 and 2 1% in responders (P < 0.01).
Conclusions: Application of recruiting maneuvers improves
oxygenation only in patients with early ARDS who do not have
impairment of chest wall mechanics and with a large potential
for recruitment, as indicated by low values of Est
L
.
TRADITIONAL respiratory support for the acute respira-
tory distress syndrome (ARDS) involves the use of rela-
tively large (10 –15 ml/kg) tidal volumes (V
T
) to mini-
mize atelectasis and positive end-expiratory pressure
(PEEP) to improve arterial oxygenation by means of low
inspiratory oxygen fractions (FIO
2
).
1
More recently, lung-
protective ventilatory strategies have been proposed
2
that are based on the large body of animal data indicating
that mechanical ventilation with high V
T
is associated
with pulmonary injury indistinguishable from ARDS.
3
Cycling end-expiratory collapse with tidal inflation may
exacerbate this process.
4
Three recent randomized con-
trolled trials supported these experimental findings,
showing that a lung-protective ventilatory strategies
based on low V
T
is able to decrease markers of pulmo-
nary and systemic inflammation
5
and decrease mortality
among patients with ARDS.
6,7
The American–European consensus conference on
ARDS proposed periodic use of recruiting maneuvers to
prevent atelectasis when small V
T
and/or low PEEP lev-
els are used.
8
Alveolar derecruitment may occur during
mechanical ventilation with low V
T
, depending on the
FIO
2
, the regional ventilation/perfusion ratios, and the
end-expiratory lung volume.
9,10
On the basis of these
recommendations, several studies have investigated the
physiologic effects of recruiting maneuvers in patients
with ARDS.
6,10 –14
Alterations in respiratory mechanics parallel the time
course of ARDS.
15,16
Most patients with early ARDS who
have been on the ventilator for only a few days have a
static volume pressure (V-P) curve with a marked lower
inflection point (LIP) and an upper inflection point (UIP)
that occurs well above tidal inflation. By contrast, most
patients with late ARDS who have been on the ventilator
for several days often have a static V-P curve with an absent
LIP and a UIP that occurs within tidal inflation.
15,16
Impairment of chest wall mechanics in patients with
ARDS has been demonstrated
17
; recent studies suggest
This article is accompanied by an Editorial View. Please see:
Suter PM: Does the advent of (new) low tidal volumes bring
the (old) sigh back to the intensive care unit? ANESTHESIOLOGY
2002; 96:783– 4.
* Clinical attending, Servizio di Anestesiologia e Rianimazione, Ospedale Di
Venere. † Doctoral student, Dipartimento di Neuroscienze-Sezione di Fisiolo-
gia, Universita’ di Torino. ‡ Clinical attending, § Professor, and ** Associate
Professor, Dipartimento di Chirurgia–Terapia Intensiva, Cattedre di Anestesiologia
e Rianimazione, Ospedale S. Chiara, Università di Pisa. Professor, Service
de Réanimation Medicale, Hopital Henri Mondor, Université Paris XII. # Professor,
St. Michael’s Hospital, University of Toronto.
Received from the Servizio di Anestesiologia e Rianimazione, Ospedale Di
Venere, Bari, Italy; Dipartimento di Neuroscienze-Sezione di Fisiologia, Universita
di Torino, Torino, Italy; Dipartimento di Chirurgia–Terapia Intensiva, Cattedre di
Anestesiologia e Rianimazione, Ospedale S. Chiara, Università di Pisa, Pisa, Italy;
Service de Réanimation Medicale, Hopital Henri Mondor, Université Paris XII,
Paris, France; and St. Michael’s Hospital, University of Toronto, Toronto, Canada.
Submitted for publication July 6, 2001. Accepted for publication October 18,
2001. Supported by Consiglio Nazionale delle Ricerche (grant No. 95.00934) and
Ministero Universita e Ricerca Scientifica e Tecnologica (MURST)-2001, Rome,
Italy. Drs. Grasso and Mascia equally contributed to the study and should
therefore both be considered as first authors.
Address reprint requests to Dr. Ranieri: Universita Di Torino, Sezione Di
Anestesiologia e Rianinazione Ospedale S. Giovanni Battista, Corso Dogliotti 19,
10126, Torino, Italy. Address electronic mail to: marco.ranieri@unito.it. Individ-
ual article reprints may be purchased through the Journal Web site,
www.anesthesiology.org.
Anesthesiology, V 96, No 4, Apr 2002 795