3.24 Spontaneous Ventilatory Parameters
Category: UWHC Clinical Policy
Policy Number: 3.24
Effective Date: June 29, 2016
Section: Respiratory Care Services
Measurement of the patient's spontaneous breathing parameters may be useful to assess the patient's ability to
maintain adequate ventilation without the use of a mechanical ventilator. These parameters may include: minute
volume (VE), respiratory rate (RR), tidal volume (Vt), vital capacity (VC), and maximal inspiratory pressure (MIP)
also referred to as Negative Inspiratory Force (NIF).
A. The only absolute contraindication is an unstable cardiovascular status.
A. All patients will be assessed by the Respiratory Care Practitioner (RCP)
B. Therapy will be provided in accordance with a provider’s order.
C. VC & MIP/NIF will be monitored on patients suspected of having neuromuscular weakness.
A. Hand held spirometer
B. One way valve device
C. MIP/NIF pressure manometer
D. Mouthpiece, Bennett seal, nose clip, or artificial airway adapter
A. Review and the provider’s order.
B. Review patient’s chart.
C. Obtain the appropriate equipment.
D. Introduce yourself to the patient and/or family. Explain the reason for the procedure.
E. The patient's airway should be cleared of secretions prior to testing.
F. Optimize the patient’s position by having them sit up at least 30 degrees if at all possible prior to the
Patients with spinal cord injuries may have better parameters while lying supine.
G. Make certain there is no leak around the artificial airway when measuring parameters. If the patient does
not have an artificial airway, a tight seal should be obtained using a mouthpiece, or a Bennett seal and
I. VE Maneuver
1. Patients without an artificial airway will have their VE and RR measured by using a handheld
spirometer with mouthpiece and nose clips.
2. Patients with an artificial airway that are not ventilated will need to be disconnected from their
Oxygen source and may require "blow-by" O2 during collection of parameters.
J. Explain VC maneuver to patient. Attach spirometer to patient's artificial airway or mouthpiece. Instruct
the patient to take a maximal inspiration and expiration. Repeat this maneuver, allowing
the patient to rest in between trials for consistency. VC should be 10-15 cc/kg ideal body weight.
K. Explain MIP/NIF maneuver to patient. Attach a one-way valve with manometer to patient’s artificial
airway or mouthpiece. The one-way valve is positioned so that the patient is allowed to exhale after
each inspiratory effort. Have the patient maximally inhale and exhale. During exhalation the
therapist should occlude the manometer and keep it occluded throughout the next inhalation. After
complete exhalation the patient should maximally inhale. This procedure should be repeated 3 times
or as tolerated, until the maximum inspiratory pressure is obtained. If the patient does not have an
artificial airway, a mouthpiece and nose clip should be used. It is necessary that a leak is incorporated
into the system to compensate for oral pressure. MIP/NIF should be -20 cm H2O to -60cm H2O.
Respiratory Care Spinal Cord Protocol UW Health Respiratory Care Policy 1.53 RT Protocols
Approved by Director and Medical Director of Respiratory Care:
Original copy of this Policy & Procedure is available in the Respiratory Care Office [E5/489].