Factors That Affect Manual Ventilation of Intubated Patients

Abstract

Background:

Bag-valve resuscitators are used to manually ventilate intubated patients. The purpose of this study was to identify factors that affect manual ventilation performance (MVP). We hypothesized that there would be no significant difference in MVP determined by experience or hand-size, when using a regular adult 1,600 mL or small adult 1,000 mL bag-valve resuscitator.

Methods:

IRB approval was obtained from Northeastern University before collecting data. This was a non-randomized study evaluating MVP. Both sizes of CPR Bag resuscitators (Mercury Medical, Clearwater, FL) were tested with registered respiratory therapists (RRTs) (n = 10) using a single compartment of the model 2600i dual adult training test lung (Michigan Instruments, Grand Rapids, MI), set to simulate a 75 kg adult with a lung impedance of Cp 0.03 L/cm H₂O, Raw 15 cm H₂O/L/s intubated with a size 8.0 mm ID ETT (Mallinckrodt, St. Louis, MO). A NICO Novametrix Cardiopulmonary Monitor (Respironics, Carlsbad, CA) via CO₂ flow sensor was used to record f, V_T, V_E, I:E ratio, PIP, and PIF minute averages. Clinical simulations involved participants manually ventilating the test lung 5 min with 3 repetitions, 15 min for both sized resuscitators (30 min total/participant). Participants were given a scenario to manually ventilate a recently intubated patient with an unknown medical history. All participants took a survey to report their professional experience. Continuous data was analyzed with ANOVA and student t-test, non-parametric data was analyzed with a Mann-Whitley U test using SPSS v27 (IBM, Armonk, NY). A P value < .05 was considered significant.

Results:

Significant difference was observed for mean V_T with regular 1,600 mL bag (500 ± 133 mL) vs. small 1,000 mL bag (390 ± 90 mL) (P = .029). Experience > 4 yrs. had a significant effect on PIP (P = .037) and PIF (P = .033). Positive correlation was observed for I:E ratio and V_E (R .763, P < .001). While there was no significant difference in V_E with experience, resuscitator size and hand size (P >.05), a wide range in V_E was noted.

Conclusions:

Adult resuscitator bag size and experience significantly affects MVP for V_T, PIP and PIF. More research with a larger test cohort is needed to understand what factors affect manual ventilation of intubated patients.

Fig. 1. Delivered tidal volume with 1600 mL vs. 1000 mL CPR bag, P= .029

Fig. 2. Experience effect on peak inspiratory pressure, P= .037