Page 563 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 44: Noninvasive Ventilation 383

■ POSTOPERATIVE RESPIRATORY FAILURE not consistently translated into hospital and ICU stay and mortality rate

Several studies looked at the use of NIPPV after surgery. 123,136-139 In many reduction. 151,153 No difference compared to standard weaning process
Similarly, mechanical ventilation–
was reported in several studies.
152,154
of them, the prophylactic or therapeutic application of NIV improved
arterial blood gases and lowered the risk of intubation albeit without associated complications, notably pneumonia and sepsis, were either
or remained unaffected by this strategy. In the most
reduced
152
151,153,154
any effect on patient outcomes. Auriant et al conducted a randomized
139
controlled trial in patients who experienced respiratory distress after recent multicenter trial, extubation followed by NIPPV or extubation
followed by standard oxygen therapy was identical with respect to wean-
lung resection. Because reintubation shortly after lung surgery carries 155
123
a very grim prognosis, avoiding ETI in this situation is an important ing success and reintubation. Based on the current evidence, NIPPV
cannot be proposed as an alternative to standard weaning process.
goal. NIPPV was indeed associated with lower ETI rates and higher hos-
NIPPV in patients with ARF after bilateral lung transplantation. Thus, ■ PATIENTS WHO SHOULD NOT BE INTUBATED
pital survival. An uncontrolled study also suggested a beneficial effect of
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137
NIPPV seems useful in preventing reintubation after lung surgery. Several reports have described the effects of NIPPV in patients with
Besides lung surgery, hypoxemia is also frequent following abdomi- ARF who were poor candidates for ETI because of advanced age, debili-
nal surgery with 8% to 10% of patients finally requiring intubation and tation, or a “do-not-intubate and/or -resuscitate” order. 9,10,156-158 Palliative
invasive MV. In this setting, CPAP ventilation may be valuable in NIPPV has been proved feasible and well tolerated with an overall
138
attenuating the effects of atelectasis on lung function and preventing fur- survival rate of 50% to 70%, depending on the patient population.
158
ther deterioration. Squadrone and coworkers demonstrated that prompt Nonetheless, when it comes to severely impaired patients, the great
implementation of CPAP in patients developing hypoxemia after major concern is not to exchange life prolongation with patient’s physical and
abdominal elective surgery averted respiratory deterioration and signifi- psychological disposition. Recently, in a large observational multicenter
cantly reduced the incidence of ETI in comparison to standard oxygen trial, Azoulay and coworkers assessed patients’ mortality, health-related
treatment. Days spent in ICU and the rate of infectious complications quality of life and patients’ and relatives’ signs of anxiety, depression,
138
decreased accordingly. Overall, a preventive use of NIPPV (CPAP or and posttraumatic stress at 90 days. The results were compared between
PSV and PEEP) seems very attractive in this population. patients receiving NIPPV in the context of a do-not-intubate order ver-
■ POSTEXTUBATION RESPIRATORY FAILURE sus patients with no treatment limitation decisions. Hospital mortality
19
in the do-not-intubate group was 46% but, interestingly, there was no
Approximately, 10% to 20% of critically ill patients fulfilling all weaning decline at 90 days in health-related quality of life and no differences
criteria and succeeding a weaning trial will fail extubation and NIPPV between the two groups in terms of patients’ and their relatives’ mental
has been proposed as a way to avert this event. 140,141 The physiological health, anxiety, depression, or posttraumatic stress disorder. One obvi-
rationale for this approach in patients with COPD was well demon- ous limitation is that quality of life could only be assessed in survivors
strated by Vitacca and coworkers who showed equivalent values of the but according to these results, NIPPV seems a meaningful option in
work of breathing under the same ventilatory support delivered before critically ill patients in whom ETI is not deemed valuable.
extubation or as NIPPV after extubation. 142 ■
Several studies addressed the role of NIPPV in preventing reintubation PATIENTS WITH SEVERE ACUTE ASTHMA
with unequivocal results. 143,144 Clinical data suggest that if postextubation Few studies indicate that NIPPV can be used in asthmatic patients. Two
respiratory failure develops, delivering NIPPV treatment at this stage is cohort studies found beneficial short-term effects of NIPPV in asthmatic
often futile and, instead, may delay reintubation and increase mortality, patients whose condition was deteriorating despite medical therapy. 159,160
as suggested by a large multicenter trial of Esteban and associates. 144,145 In a recent trial, all patients treated for acute asthma received intra-
161
By contrast, early or preemptive delivery of NIPPV after extubation to venous corticosteroid therapy and were subsequently randomized in
prevent subsequent respiratory failure may be useful depending on the three groups: (a) a group in which NIPPV was applied with a pressure
population tested. In patients selected to be at high risk of extubation support level of 4 cm H 2O and a PEEP of 6 cm H 2O, (b) a group where
failure, NIPPV was demonstrated to prevent postextubation respiratory PSV and PEEP during NIPPV were 6 and 8 cm H 2O, respectively, and
failure and reintubation in several trials. A survival benefit was also dem- (c) a third group treated only with oxygen. A greater reduction in dyspnea
onstrated in the subgroup of patients who were hypercapnic during the was observed in the NIPPV groups compared to the control group. The
weaning test. 146,147 Intubation rates and mortality have been shown to be second NIPPV group (high pressure level group) demonstrated a signifi-
reduced in other group of at-risk patients, older than 65 years old and with cant improvement in the forced expired volume in one second (FEV 1)
cardiac or respiratory comorbidities. 143,148 These beneficial effects are not compared to the control group. A benefit in clinical outcome could not
observed if NIPPV is applied routinely in all extubated patients as shown be demonstrated possibly due to the small number of patients.
149
by Su and coworkers who randomized 406 unselected patients to either
NIPPV or supplemental O 2 mask, early following their extubation. In line ■ NEW MODES OF VENTILATION
150
with previous observations, both treatment strategies were equivalent in
terms of reintubation or mortality rates. In conclusion, the determinants Several studies used a very physiologically sound ventilatory mode known
149
of NIPPV success in the postextubation period are (1) judicious selection as proportional-assist ventilation, which is designed to improve the
of patient population. Patients with risk factors for reintubation—notably adjustment of ventilatory support to the patient’s needs. 162-165 In several
underlying respiratory disease and/or hypercapnia during the weaning comparative studies with pressure-support ventilation in one of the arms,
test—are more likely to benefit, (2) prompt application of NIPPV imme- the efficacy of the two techniques seemed similar, although very few
diately after extubation and prior to respiratory failure development, and patients required ETI. Studies in patients with greater disease severity are
(3) close patient monitoring to minimize delays in ETI, if needed. needed. A prospective randomized trial by Fernandez-Vivas and associ-
■ WEANING ates in 117 patients with mixed causes of ARF again showed no difference
in clinical outcomes between NIPPV delivered with pressure support or
165
A number of patients with COPD require ETI because they fail NIPPV, with proportional-assist ventilation. Subjective comfort was better with
have a contraindication to NIPPV (such as a need for surgery), or proportional-assist ventilation, and intolerance was less common. Leaks,
however, make the settings of this mode particularly difficult during NIV.
exhibit criteria for immediate ETI. When there is a need for prolonged
This ■
ventilatory assistance, these patients can be switched to NIPPV after a
few days of ETI to reduce the time with a tube in the trachea. 151,152 FIBEROPTIC BRONCHOSCOPY
approach was examined in several trials with contradictory results. 151-155 Several studies have demonstrated that fiberoptic bronchoscopy can be
Extubation and times with ETI were usually hastened. However, this was performed under NIPPV (CPAP for hypoxemic patients or pressure

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