NIPPV Prediction

Objective

To identify predictors of noninvasive positive pressure ventilation (NIPPV) failure in patients with acute hypercapnic respiratory failure using the Common Longitudinal ICU data Format (CLIF).

Outcome Definition

NIPPV Failure is defined as:

1. Death or
2. Escalation to invasive mechanical ventilation

within 48 hours of NIPPV initiation.

Predictors

Unless otherwise specified, physiologic predictors are defined as the median value 1-12 hours following NIPPV initiation. Continuous variables are scaled to improve interpretability of regression coefficients.

1. age_scale
   • Age scaled per 10-year increase
2. female
   • Female vs. Male (reference); binary (0/1)
3. pco2_scale
   • Median pCO2 (arterial or venous) scaled per 10 mmHg increase
4. ph_scale
   • Median pH (arterial or venous) scaled per 0.1 unit increase
5. map_scale
   • Median mean arterial pressure (MAP) scaled per 10 mmHg increase
6. rr_scale
   • Median respiratory rate scaled per 5 bpm increase
7. hr_scale
   • Median heart rate scaled per 10 bpm increase
8. fio2_high
   • Median FiO2 > 0.4 vs. <= 0.4 (reference); binary (0/1)
9. peep_scale
   • Median positive end-experatory pressure (PEEP) scaled per 2 cmH2O increase
10. tidal_volume_scale
    • Median Tidal volume scaled per 100 mL increase
11. age_scale * ph_scale
    • Age-acidosis interaction
12. pco2_scale * rr_scale
    • Hypercapnia-respiratory rate interaction.

Cohort Identification

Inclusion Criteria:

1. NIPPV initiation within 6 hours of the first recorded vital sign
2. Median pCO2 (arterial or venous) >= 45 mmHg prior to NIPPV initiation
3. Median pH (arterial or venous) <= 7.35 prior to NIPPV initiation

Exclusion Criteria:

1. Median FiO2 >= 0.6 prior to NIPPV initiation

Output

The following csv files are generated:

1. consort.csv
   • cohort counts used to construct the CONSORT diagram
2. descriptive_caractersitics.csv
   • Baseline characteristics stratified by NIPPV failure
   • Continuous variables compared using t-tests
   • Categorical variables compared using chi-squared tests
3. multivariable_logistic_results_Interaction.csv
   • Multivariable logistic regression results including interaction terms
4. multivariable_logistic_results_NoInteraction.csv
   • Multivariable logistic regression results without interaction terms
5. univariate_logistic_resuts_Interaction.csv
   • Univariate logistic regression results including interaction terms
6. univariate_logistic_results_NoInteraction.csv
   • Univariate logistic regression results without interaction terms