Adaptation of NIV in a unit requires education, a program of development, and an opportunity to provide feedback to the team [7]. The main reasons for low use of NIV are lack of physician knowledge, inappropriate NIV equipment, poor previous experience, and inadequately trained staff. Experience in NIV is the most important precondition for success in adaptation of NIV in acute patients. The location for starting NIV should have facilities for monitoring, rapid access to endotracheal intubation and invasive ventilation, and an adequate number of experienced staff. The model of hospital care varies from country to country. The most important factors in determining where NIV should be started are need for monitoring, monitoring capabilities of the unit, experience of the staff, and time response to NIV. NIV should be started early, immediately after the patient’s consent, because a delay may permit further deterioration and increase the likelihood of failure. The physician has an obligation to identify the disease to be treated with NIV and to exclude from NIV patients with contraindications. Continuous monitoring is needed to verify the clinical efficacy. Adherence to NIV may be improved by providing suitable humidification, and patient comfort may be improved by a soft sedation. Patient motivation is a critical issue for adaptation during NIV to enhance favorable outcomes [7].
81.4 Adaptation to NIV in the Chronic Setting
There are two important and distinct strategies for the use of NIV in the chronic setting: one COPD and another in restrictive thoracic diseases, obesity hypoventilation syndrome, and neuromuscular disorders with chronic RF.
The rationale for long-term NIV for COPD patients is still disputed. Fortunately, a promising NIV technique has been described and introduced into clinical practice [8]. High-intensity NIV is defined as long-term (chronic) NIV aimed at maximally improving gas exchange. This means that the patient should achieve normocapnia or, if hypercapnia cannot be totally avoided, the lowest possible level of pCO2 in arterial blood using high ventilatory settings, as maximally tolerated or necessary. From the physiological point of view, high-intensity NIV is an effective procedure and improves several variables and parameters. High-intensity NIV now is the first-choice method for home mechanical ventilation in patients with COPD.
This approach clearly contrasts with the conventional, low-intensity approach. It might be speculated that high-intensity NIV would not be as well tolerated as low-intensity NIV in COPD. In fact, the opposite is true: patients spent, on average, 3.6 more hours per day on NIV when using high-intensity NIV compared with the low-intensity strategy. Interestingly, dropouts occurred in the low- but not the high-intensity group. More effective ventilation, as achieved by more aggressive forms of NIV, results in better patient adherence, which is attributable to improved quality of life and more effectively ameliorated symptoms [8].
An important part of the adaptation process with high-intensity NIV for COPD patients consume is the time spent on the introduction. More days (on average 2.5) were spent in the hospital to acclimatize patients to high-intensity NIV compared with low-intensity NIV. Other important factors include greater amounts of leakage during night ventilation and induction in cardiac output. Special consideration should be given to patients with heart failure and antihypertensive treatment. High-intensity NIV is typically established in a step-wise approach in the hospital [8]. The typical order of single steps for initiation and optimal adaptation, as well as pitfalls and problem-solving advice for individual tracks of the adaptation process, have been precisely described by Windisch [8] and are presented in Table 81.1.
Table 81.1
Practical approach for high-intensity NIV adaptation and problem solving in patients with COPD [8]
Adaptation approach for high-intensity NIV |
Use NIV in the daytime first, with the primary aim of establishing tolerance, but also with control of blood gases and vital parameters including blood pressure |
Start with assisted NIV first For this purpose, the lowest back-up respiratory rate and most sensitive trigger threshold are typically used in addition to low inspiratory positive airway pressure (IPAP) levels, normally ranging between 12 and 16 cmH2O Expiratory positive airway pressure (EPAP) levels are low at this time |
Once assisted NIV is tolerated, carefully increase IPAP in a step-wise approach until maximal tolerance is reached, usually up to 30 (range 20–40) cmH2O The tolerated maximum may differ greatly between individuals |
Increase the respiratory rate just beyond the spontaneous rate (not more) to establish controlled ventilation, but avoid excessively high respiratory rate settings that cause dynamic hyperinflation |
Set EPAP to avoid dynamic hyperinflation according to subjective comfort (usually 3 and 6 cmH2O), and, similarly, set the inspiratory:expiratory ratio to 1:2 or lower EPAP settings may be higher when upper airway obstruction is simultaneously treated (COPD + obstructive sleep apnea syndrome) |
Once daytime tolerance is acceptable, apply nocturnal NIV Do not apply nocturnal NIV too early when the patient is not comfortable with daytime NIV |
Adjust ventilator settings according to subjective tolerance and nocturnal monitoring of blood gases. Sometimes settings can be modified considerably at the first control visit in the hospital after the patient has been acclimatized to NIV at home for some weeks |
Problem solving in adaptation to high-intensity NIV |
Tolerance of higher IPAP levels can last from minutes to several days or even weeks: individual adjustment is inevitable Sometimes significant modification of settings is feasible at the first control in-hospital visit after having discharged patients for acclimatization in the home environment |
In cases of coexisting upper airway obstruction, higher EPAP levels are required On the other hand, higher EPAP reduces the effective IPAP (which is IPAP minus EPAP); thus, avoid high EPAP levels if not required |
For controlled NIV (final aim), respiratory rates are typically set to 1 breath·min−1 higher than during spontaneous breathing; thus, avoid excessively high respiratory rates, even though controlled ventilation is the aim |
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