Question 11

College answer

Not available.

Discussion

Suitability for intubation:

• Presence of reversible physiological factors which intubation might address, such as:
  • Respiratory acidosis
  • Decreased level of consciousness
  • Fatigue due to high respiratory workload
• Absence of existing treatment limitation orders
• Absence of features which might suggest futility, i.e. where chances of success are impossibly small (eg. multiorgan system failure, severe shock, extreme frailty, etc)
• Insufficient information to guide robust end-of-life decisionmaking (Wildman et al, 2007; prognostic pessimism may deny intubation to potentially salvageable patients)

Factors which favour a beneficial effect from invasive ventilation:

• Acute exacerbation of COPD as the cause of respiratory failure -Nevins et al (2001) found that the in-hospital mortality was only 12% for these people, as compared to 28% for the rest of the cohort
• Higher premorbid FEV₁ (over 1.2) - this is the GOLD score (Mannino et al, 2006); GOLD stage 3 or 4 (FEV₁/FVC<0.70 and FEV₁<50% predicted) is associated with a mortality of around 35% at ten years.
• Good baseline function  -low BODE index (Celli et al, 2004)
• Pneumonia as the cause of this exacerbation would favour HFNP or invasive ventilation instead of NIV, as NIV may even be counterproductive (by impairing the clearance of secretions, for example)

Factors which predict a poor outcome from intubation:

• Failure of NIV, particularly if the patient is elderly - Chandra et al (2012) found that the in-hospital mortality for these people was 33%; non-survivors were largely elderly (over 55% of them were aged 75 or older)
• Poor baseline function indices - BODE index 7-10 (Low BMI, breathless at rest and unable to walk more than 150m over six minutes, with an FEV₁ below 35% of the predicted value) =  20% chance of surviving the next 48 months.
• Poor global assessment of function -  Menzies et al (1989) found that if the patient is unable to leave their house because of their symptoms, their ICU mortality was with intubation 71%, going up to 75% if they were chronically bedbound or chairbound.
• Dependence on home oxygen: according to Hajizadeh et al (2015) there is 23% in-hospital mortality, 45% 1-year mortality and  26.8% were discharged to a nursing home within 30 days.
• Comorbidities (Menzies et al, 1989):
  • Malignancy
  • Cor pulmonale
  • Chronic hypercapnia
  • Left ventricular failure

Patient and family preferences

• The patient's autonomy needs to be respected (they may have strong views on the matter)
• It is important to remain objective - physicians can influence patient opinion significantly depending on how they "spin" their explanation of intubation and mechanical ventilation ( Sullivan et al, 1996)
• For some scenarios, invasive ventilation has a good chance of success (ICU mortality for the "pure" COPD cohort from Nevins et al (2001) was actually lower than for other acute respiratory pathologies - 9% ICU mortality and 17% hospital mortality).
• Survivors of short ICU stay with invasive ventilation rate their post-discharge health as same or better, and 96% responded that they would be willing to undergo similar treatment again (Wildman et al, 2009). These patients stayed in ICU for 6-9 days on average.