Page 557 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 44: Noninvasive Ventilation 377

to exclude clinical conditions that occasionally cause reduced respira- CHAPTER Noninvasive Ventilation
tory muscle strength. Neuromuscular disease, muscle-relaxing drugs,
69
steroids, sedatives and opiates, coma, and intercurrent cerebrovascular Laurent Brochard
70
accidents cause obscure reductions in respiratory muscle strength. 44 Evangelia Akoumianaki
71
Though uncommon, some overlooked causes of inadequate respiratory
muscle function are sub-clinical status epilepticus, hypothyroidism, and Ricardo Luiz Cordioli
paralysis of the phrenic nerve on one or both sides after cardiac surgery
or other thoracic trauma. 64,65 KEY POINTS
While strategies to accelerate liberation from the ventilator often
focus on diaphragmatic and respiratory muscle function, decondition-
ing and neuromuscular weakness is a phenomenon that affects the entire • Many patients with ventilatory failure can be successfully managed
patient in critical illness. Recent studies have demonstrated that early with noninvasive positive pressure ventilation (NIPPV).
71
rehabilitation and mobilization of the entire patient by means of bedside • NIPPV improves gas exchange, reduces the work of breathing, and
physical and occupational therapy resulted in an increase in ventilator- relieves dyspnea.
free days. These data suggest that early mobilization of the patient once • Patients most likely to benefit include those with acute hypercapnic
72
hemodynamically stable may aid in liberating the patient from mechani- exacerbations of chronic obstructive pulmonary disease (COPD)
cal ventilation. or hypercapnic forms of acute cardiogenic pulmonary edema.
• In selected patients with acute hypoxemic nonhypercapnic respi-
ratory failure, NIPPV may obviate the need for endotracheal
intubation. Selection may require exclusion of patients with hemo-
KEY REFERENCES dynamic instability, central neurologic dysfunction, or inability to
protect the upper airway.
• Hall JB, Wood LDH. Liberation of the patient from mechanical • In severely hypoxemic patients, undiscerning use of NIPPV may
ventilation. JAMA. 1991;257:1621-1628. inappropriately delay intubation. In these patients, the decision to
• Hebert PC, Wells G, Blajchman MA, et al. A multicenter, ran- switch to endotracheal intubation should be made in the first hours.
domized, controlled clinical trial of transfusion requirements • The use of NIPPV to treat postextubation respiratory distress has not
in critical care. Transfusion Requirements in Critical Care been found to be superior to conventional management. Preventive
Investigators, Canadian Critical Care Trials Group. N Engl J Med. use of NIV in selected group of patients may, however, be useful.
1999;340(6):409-417. • The first hour on NIPPV is important in predicting the outcome
• MacIntyre NR, Cook DJ, Ely EW, et al. Evidence based guidelines and requires experience from clinicians and to spend time at the
for weaning and discontinuing ventilatory support: a collective bedside with the patient.
task force facilitated by the American College of Chest Physicians, • A favorable response to NIPPV is usually apparent within the first
the American Association for Respiratory Care, and the American 2 hours. Absence of improvements in dyspnea, respiratory rate, and
College of Critical Care Medicine. Chest. 2001;120:375S. gas exchange in this period strongly suggests a need for endotra-
• Malo J, Ali J, How does PEEP reduce intrapulmonary shunt in cheal intubation.
canine pulmonary edema. J Appl Physiol. 1984;57:1002. • Typical settings in a patient with COPD include pressure sup-
• Manthous CA, Hall JB, Kushner R, et al. The effect of mechanical port of 10 to 15 cm H 2O above a positive end-expiratory pressure
ventilation on oxygen consumption in critically ill patients. Am J (PEEP) of 5 cm H 2O.
Respir Crit Care Med. 1995;151:210. • In appropriately selected patients, NIPPV allows a shorter hos-
• Manthous CA, Schumacker PT, Pohlman A, et al. Absence of pital stay and produces better outcomes than does endotracheal
supply dependent of oxygen consumption in patients with septic mechanical ventilation.
shock. J Crit Care. 1993;8:203.
• The National Heart L, Blood Institute Acute Respiratory Distress Noninvasive positive pressure ventilation (NIPPV) has emerged as a
Syndrome (ARDS) Clinical Trials Network. Ventilation with valuable tool in the treatment of acute respiratory failure (ARF). NIPPV
lower tidal volumes as compared with traditional tidal volumes can substantially reduce the need for endotracheal intubation (ETI) and
for acute lung injury and the acute respiratory distress syndrome. mechanical ventilation (MV). In selected patients, the benefits of NIPPV
The Acute Respiratory Distress Syndrome Network. N Engl J Med. include decreased rates of adverse events associated with MV, shorter
2000;342(18):1301-1308. time spent in the intensive care unit (ICU) and hospital, and lower
• Rivers E, Nguyen B, Havstad S, et al. Early goal-directed therapy mortality rates. Patients with hypercapnic forms of ARF are most likely
in the treatment of severe sepsis and septic shock. N Engl J Med. to benefit, but NIPPV may also improve outcomes of carefully selected
2001;345:1368. patients with hypoxemic respiratory failure. This chapter reviews the
• Schweickert WD, Pohlman MC, Pohlman AS, et al. Early evidence supporting NIPPV use in patients with ARF.
physical and occupational therapy in mechanically ventilated,
critically ill patients: a randomized controlled trial. Lancet. RATIONALE AND OBJECTIVE
2009;373(9678):1874-1882.
• Schumacker PT. Oxygen supply dependency in critical illness: an When MV was first developed for widespread clinical use during the polio-
myelitis epidemic, attention focused on replacing the failing respiratory
evolving understanding. Intensive Care Med. 1998;24:97-99. muscles by a perithoracic pump. This led to the development of the “iron
lung,” the first form of noninvasive ventilation, which saved many lives.
1,2
Nevertheless, the device was cumbersome and impeded patient care. In addi-
tion, the iron lung proved of limited efficacy in the treatment of parenchymal
REFERENCES lung disease. Thus delivery of mechanical assistance through an endotracheal
tube that provided access to the lower airway was considered a significant
Complete references available online at www.mhprofessional.com/hall advance, and positive pressure ventilation became the standard for MV.

section04.indd 377 1/23/2015 2:18:44 PM