Can Non-Invasive Ventilation (NIV) duration be decreased for a patient with alkalosis, hypercapnia, and hypoxemia, who is currently on continuous NIV and rehabilitation?

From the Guidelines

Decreasing the NIV duration to allow for 3-hour breaks during meals instead of continuous use may be considered, but it is crucial to closely monitor the patient's response and adjust the plan as needed to prevent deterioration in respiratory status. The patient's current ABG results show improvement with a normalized pH of 7.458 (from 7.384) and a slight decrease in pCO2 to 60.3 (from 62.2), indicating better ventilation 1. The bicarbonate level of 43.3 suggests chronic respiratory acidosis with metabolic compensation. While the pO2 has decreased to 86.5 (from 119), the SpO2 remains adequate at 96.9%.

When implementing this change, it is essential to monitor the patient for signs of respiratory distress during NIV breaks, including increased work of breathing, tachypnea, or decreasing oxygen saturation. Schedule reassessment with repeat ABGs after 24-48 hours of the new regimen to ensure the patient maintains adequate gas exchange. If the patient tolerates these breaks well, you could consider gradually extending NIV-free periods, but if deterioration occurs, return to the previous continuous NIV schedule immediately. This approach allows for improved quality of life while maintaining respiratory support. According to the BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults, normalization of pH and a pCO2 < 6.5 are commonly used as a guide to the discontinuation of NIV, but the optimal amount of NIV and the most effective way to withdraw it have not been examined in published trials 1.

Key considerations for adjusting NIV duration include:

• Monitoring pCO2 on and off NIV to guide the withdrawal of NIV
• Gradually reducing the amount of time on NIV, with increasingly prolonged periods of self-ventilation during the day
• Continuing with NIV overnight
• Adjusting ventilator settings to achieve patient comfort and mirror patient recovery
• Assessing for alternative or additional causative factors such as marked fluid retention, obstructive sleep apnoea (OSA), or obesity hypoventilation syndrome (OHS) if the patient has a less clear infective cause for AHRF or evidence of chronicity of hypercapnia.

From the Research

Patient Assessment

• The patient's current ABG values show a pH of 7.458, pCO2 of 60.3, pO2 of 86.5, Hco3 of 43.3, and Spo2 of 96.9.
• Compared to the previous values, the patient's pH has increased, pCO2 has decreased, pO2 has decreased, Hco3 has increased, and Spo2 has decreased.

Non-Invasive Ventilation (NIV) Management

• The patient is currently on NIV round the clock and undergoing rehabilitation.
• The question is whether the NIV duration can be decreased, such as being off for 3 hours during meals instead of continuous use.
• According to the study 2, NIV can be successfully used in patients with acute hypercapnic respiratory failure (AHRF) resulting from acute cardiogenic pulmonary edema (ACPE), chronic obstructive pulmonary disease (COPD), or obesity hypoventilation syndrome (OHS), even in those with severe acidosis.
• However, the study 3 suggests that NIV may have deleterious effects, especially in patients generating strong inspiratory efforts, and that protective NIV using higher levels of positive-end expiratory pressure, more prolonged sessions, and additional interfaces such as helmets should be assessed in the future.
• The study 4 found that metabolic acidosis in addition to respiratory acidosis is an unfavorable element, as it determines an increased need for NIV and invasive mechanical ventilation support.
• The study 5 showed that short-term NIV post-surgery improves arterial blood-gases in obese subjects compared to supplemental oxygen delivery.
• The study 6 reported that NIV use in clinical practice reveals higher mortality rates than in corresponding randomized clinical trials, and that some eligible patients failed to receive NIV, while others received it inappropriately.

Considerations for NIV Duration

• Based on the patient's current ABG values and the studies mentioned above, it is unclear whether decreasing the NIV duration would be beneficial or harmful.
• The decision to decrease NIV duration should be made on a case-by-case basis, taking into account the patient's individual needs and response to treatment.
• It is essential to closely monitor the patient's ABG values, clinical status, and response to NIV to determine the optimal duration of NIV use 2, 3, 4, 5, 6.