Page 746 - Clinical Application of Mechanical Ventilation

712 Glossary

hyperbaric condition: An environment in which the atmospheric pressure is greater than one barometric pressure (e.g.,
diving under water, hyperbaric chamber).
hyperbaric oxygen: Supplemental oxygen under hyperbaric conditions; used in conditions such as severe carbon
monoxide poisoning, decompression sickness, gas gangrene, and anaerobic infections.
hypobaric condition: An environment in which the atmospheric pressure is less than one barometric pressure (e.g.,
high altitude, airplane cabin in flight).
hypopnea: Reduction in airflow for 10 or more seconds that is at least 50% below an estimated baseline amplitude,
usually associated with oxygen desaturation or pulse alteration.
hypoventilation: Below normal level of alveolar ventilation characterized by an elevated PaCO .
2
hypoxemia: Deficiency of oxygen in blood; low PaO .
2
hypoxia: Deficiency of oxygen in tissues.

hypoxic hypoxia: Lack of oxygen in the organs and tissues due to a reduction in inspired oxygen tension.
hypoxic-ischemic encephalopathy (HIE): A condition caused by a severe lack of oxygen supply to the brain leading to
damage to the cells and neurons of the brain and spinal cord.
I:E ratio: A time ratio comparing the inspiratory time and expiratory time, normally between 1:2 and 1:4 in
mechanical ventilation. This ratio is regulated by the inspiratory flow rate, I time, or E time and is affected by the
tidal volume and respiratory rate.
impedance cardiography (ICG): A noninvasive procedure to measure or trend the hemodynamic status of a patient.

impending ventilatory failure: A gradual increase of PaCO (.50 mm Hg) caused by deteriorating lung functions.
2
inotropic: Affecting the contraction.
inspiratory positive airway pressure (IPAP): An airway pressure that is above 0 cm H O during the inspiratory phase of
2
a respiratory cycle.
inspiratory time: Time from beginning inspiration to end of inspiration/beginning expiration.
interhospital transport: Moving a patient between two hospitals.
intermittent mandatory ventilation (IMV): A mode in which the ventilator delivers control (mandatory) breaths and
allows the patient to breathe spontaneously to any tidal volume the patient is capable of between the mandatory
breaths.
intra-abdominal pressure (IAP): Pressure measured by a transducer via a transurethral bladder catheter.

intracellular fluid (ICF): Fluid within the cells. It accounts for 40% of total body water.
intrahospital transport: Moving a patient between two locations within the hospital.
intrapulmonary shunting: Pulmonary blood flow in excess of ventilation; wasted perfusion (e.g., atelectasis).
inverse ratio pressure-controlled ventilation (IRPCV): A mode of ventilation in which the peak inspiratory
pressure is preset and the I time is longer than the E time. Same as pressure-controlled inverse ratio
ventilation (PC-IRV).
laryngeal mask airway (LMA): A tube with a small cushioned mask on the distal end that provides a seal over the
laryngeal opening.
laryngoscope: An instrument that is used to displace the tongue and soft tissues, and visualize the larynx and vocal
cords during endotracheal intubation.
lidocaine: A medication used to reduce irritation of the mucosal membrane caused by the insertion tube.
lung compliance: The degree of lung expansion per unit pressure change.
lung protection strategy: A method to prevent the lungs from pressure- or volume-induced injuries during mechanical
ventilation,

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