Chapter 85: Controversies: Noninvasive Ventilation at the End-of-Life—Useful or Not?

INTRODUCTION

Noninvasive ventilation (NIV) has been well described as effective in different patient populations, for example, hypercapnic respiratory failure due to exacerbations of chronic obstructive pulmonary disease (COPD),¹ hypoxic respiratory failure in immunocompromised hosts,² or cardiogenic pulmonary edema in the absence of acute coronary ischemia,³ to cite the most common indications.

Conceptually, the use of noninvasive ventilation can be divided into the following three categories⁴:

1. NIV as a part of “full-code” treatment (life support without preset limits)

2. NIV in patients with do-not-intubate orders (life-support with preset limits)

3. NIV as a comfort measure in patients at the end-of-life (NIV ensuring comfort while dying)

Each category has specific goals of care, response to failure, and main points to communicate with the patient and/or family. Categories 2 and 3 can be defined as palliative NIV.⁵

The goals of NIV in patients in category 1 are to alleviate symptoms of respiratory distress, improve oxygenation and/or ventilation, avoid intubation, and reduce the risk of mortality. Endotracheal intubation is performed if necessary.

Patients in category 2 are those who decline endotracheal intubation or patients in whom clinicians feel that intubation would not meet the goals of care. In this group, the use of NIV achieves the same goals as it does in category 1, except that endotracheal intubation is not an option in cases where NIV is ineffective.

The only purpose of NIV in category 3 is symptom palliation and patient comfort.

SYMPTOMS OF RESPIRATORY DISTRESS AT THE END OF LIFE

Respiratory distress is one of the most common symptoms seen in patients approaching the end-of-life. It leads to restrictions in quality of life and increases anxiety and fear.⁶

Terminal dyspnea is a manifestation of an irreversible process, such as carcinomatous lymphangitis in malignant diseases or advanced degenerative neuromuscular disease (amyotrophic lateral sclerosis).

The vast majority of patients with terminal cancer experience symptoms of respiratory distress at some point during the last 6 weeks of life, and they commonly report significantly increased dyspnea during the last two weeks.⁷ In patients with a noncancer terminal diagnosis, such as COPD or chronic heart failure (CHF), the severity of respiratory distress can be greater; however, the severity remains relatively stable until death.

RESPIRATORY DISTRESS RELIEF BY USING NIV

The mechanism underlying the relief of respiratory distress through noninvasive ventilation remains the same in all clinical situations.⁸ NIV reduces the work of breathing by increasing transpulmonary pressure and reducing inspiratory muscle workloads. Gas exchange is improved by increasing alveolar ventilation, functional residual capacity, opening collapsed alveoli, reducing shunts, and improving the ventilation/perfusion (V/Q) ratio. Altogether, these mechanisms result in a lower respiratory rate, reduced CO₂ retention, and an overall improvement of ...