High-Frequency Oscillatory Ventilation in Adults: Patient Outcomes With HFOV

Patient outcomes and the use of concomitant therapies for ARDS such as inhaled nitric oxide (NO) are presented in Table 2. The median duration of HFOV therapy in all patients was 3.5 days (25 to 75% CI, 0.8 to 6.8 days). Neuromuscular blocking agents were administered continuously during HFOV therapy to 90% of patients. Twenty-one percent of patients exhibited spontaneous respirations at some time during HFOV therapy. At 30 days, the mortality rate was 61.7%. Of the survivors, approximately half still required ventilatory support. The mortality rate remained constant throughout the 4 years.
Survivors vs Nonsurvivors
Table 3 shows the baseline characteristics of survivors and nonsurvivors prior to receiving HFOV therapy. Nonsurvivors were significantly older, had higher APACHE II scores and multiple organ dysfunction scores (MODSs), were more likely to be immunocompromised, had ARDS longer, and received CV for a greater number of days prior to receiving HFOV therapy. Baseline pH was lower and peak inspiratory pressure during CV was higher in nonsurvivors. The total duration of ventilation was greater in survivors. birth control pills Ortho Tri Cyclen
Figure 3 illustrates the temporal course of Pa02/Fio2 ratio, OI, Fio2, and PaC02 after the initiation of HFOV therapy in both survivors and nonsurvivors. mPaw was similar in survivors and nonsurvivors throughout the 72 h (data not shown). Pa02/Fl02 ratio was higher and OI was lower in survivors (p = 0.018 vs p = 0.001, respectively). Fio2 could be reduced with the application of HFOV therapy in both groups, but survivors required lower Fio2 values than did nonsurvivors (p < 0.0001). There was no difference in PaC02 between the two groups.
Predictors of Outcome
Multivariate analysis identified the following four baseline parameters that significantly predicted the 30-day mortality rate (Table 4): age (p = 0.0341); APACHE II score at ICU admission (p = 0.0317); number of CV days prior to starting HFOV therapy (p = 0.0115); and baseline pH (p = 0.0083). Stepwise logistic regression identified OI as the most significant posttreatment predictor of mortality and OI at 24 h as the most significant time point (p = 0.0066). The relationship between predicted mortality and OI at 24 h, controlling for baseline conditions, is shown in Figure 4.
We identified an OI of < 15 at 24 h or an improvement of at least 30% in the OI at > 24 h as the best dichotomous criteria for survival (sensitivity, 0.63; specificity, 0.67; p = 0.007).
Fig3
Figure 3. Pao2/Fio2 ratio (top left, A), OI (top right, B), Fio2 (bottom left, C), and Paco2 (bottom right, D) in survivors (SURV) and nonsurvivors (DIED) plotted over the study duration. CV represents values observed during CV immediately prior to initiating HFOV therapy. All subsequent measurements were made during HFOV therapy. Time 0 represents values observed within 30 min of HFOV initiation. Values are given as the mean ± SD. The numbers adjacent to each data point represent the number of trials. The p values represent the difference between survivors and nonsurvivors over the 3 days, as follows: Pao2/Flo2 ratio, p = 0.018; OI, p = 0.001; CVP, p < 0.0001; Paco2, p value not significant.
Fig4
Figure 4. The relationship between predicted mortality and OI at 24 h, controlling for baseline conditions. The interrupted lines indicate the upper and lower 95% CIs.

Table 2—Patient Outcomes Using HFOV

Outcomes Values
Duration of HFOV, d 5.1 ± 6.3
Pneumothorax during HFOV 34(21.8)
Reason for withdrawal of HFOV
Successfully weaned 76 (48.7)
Withdrawal of life support/death 38 (24.4)
Technical problem 5 (3.2)
Oxygenation difficulty 12 (7.7)
Ventilation difficulty 23 (14.7)
Hemodynamic instability 8(5.1)
Other therapies
INO 68 (43.6)
Steroids 58 (37.2)
Prone positioning 10 (6.4)
HFJV 5 (3.2)
ECMO 2(1.2)
Outcome at 30 d
Died 95 (61.7)
Alive
No ventilatory support 28 (18.2)
Ventilated 31 (20.1)

Table 3—Patient Characteristics in the Three ICUs

Characteristics MSH (n = 75) SWCHSC (n = 29) UHN (n = 52)
Age, yr 48 ± 19 41 ± 19 50 ± 16
Sex, % female 43 31 50
ARDS etiology, %
Sepsis 65 50 58
Pulmonary infection 16 35 12
Trauma 0 12 0
Other 19 4 31
APACHE II score in 1st 24 h in ICU 26.4 ± 7.4 18.0 ± 6.0 23.0 ± 6.6
Immunocompromised patients т, % 37.3 7.4 36.5
LIS 3.5 ± 0.4 3.2 ± 0.5 3.6 ± 0.3
ARDS prior to HFOV, d 4.3 ± 5.4 2.9 ± 3.0 2.8 ± 3.0
Ventilation prior to HFOV, d 5.3 ± 8.8 8.1 ± 7.0 4.7 ± 5.5
Duration of HFOV, d 6.4 ± 7.2 4.3 ± 3.9 3.6 ± 5.0
Total duration of MV, d 19.7 ± 20 23.8 ± 15.1 23.5 ± 22.7
Outcome at 30 d, %
Died 60.8 50.0 69.2
Alive
No ventilatory support 13.5 17.9 3.8
Ventilated 25.7 32.1 26.9

Table 4 —Characteristics of Survivors and Nonsurvivors

Characteristics Survivors (n = 59) Nonsurvivors (n = 95) p Value
Age, yr 42.4 ± 16.3 51.3 ± 19.0 0.0026
Sex, %
Male 48 62
Female 52 38
APACHE II
1st 24 h in ICU 21.5 ± 7.4 25.3 ± 7.3 0.0028
24 h prior to HFOV 21.0 ± 8.2 25.8 ± 7.2 0.0006
MODS 8.5 ± 3.2 8.9 ± 3.8 0.0486
Immunocompromised,! % 20.3 39.4
LIS{ 3.5 ± 0.4 3.5 ± 0.4
ARDS prior to HFOV, d 2.9 ± 3.1 4.0 ± 4.9
Ventilation prior to HFOV, d 4.4 ± 5.2 6.5 ± 8.7 0.0113
Gas exchange prior to HFOV
pH 7.33 ±.10 7.25 ±.12 < 0.0001
Paco2, mm Hg 50.2 ± 14.1 55.0 ± 21.2
Pao2/Fio2, mm Hg 92.6 ± 34.8 90.4 ± 54.4
OI§ 29.6 ± 13.8 32.5 ± 13.5
Pulmonary artery catheter, No. 16 (27%) 16 (17%)
Ventilator parameters during CV
Plateau pressure, cm H O 34.2 ± 6.5 37.3 ± 6.3 0.0065
PEEP, cm H O 14.3 ± 2.8 13.8 ± 3.4
mPaw, cm H O 24.0 ± 6.0 24.1 ± 4.4
Fio 0.84 ± 0.19 0.87 ± 0.16
Air leak prior to HFOV, % 28.8 30.5
New air leak during HFOV, % 22.0 22.1
Other therapies,| No.
INO 22 (37.2%) 46 (48.4%)
Steroids 23 (39.0%) 35 (36.8%)
Prone positioning 6(10.1%) 4 (4.2%)
HFJV 1 (1.7%) 4 (4.2%)
Duration of HFOV, d 6.8 ± 6.7 4.1 ± 5.6 < 0.0001
Total duration of MV, d 34.8 ± 23.4 12.5 ± 10.1
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