Therapeutic Gases, Respiratory Medications, and Monitoring Equipment

1. Therapeutic Gases, Respiratory Medications, and Monitoring Equipment Level 1 Mark A. Willing, RRT-NPS

2. Inhaled Medications • Bronchodilators • Steroids • Others

3. Bronchodilators • Albuterol sulfate (albuterol, Ventolin, Proventil) • Smooth muscle relaxant of small, peripheral airways • Onset of action within a few minutes • Peak effects in 15-20 minutes • Duration of effects 3-4 hours • Common side effects may include any of the below: • Tachycardia • Hyperglycemia • Hypokalemia • Lactic acidosis • Tremors • Increased pulmonary shunt • Stomach upset and reflux

4. Bronchodilators • Ipratropium Bromide (Atrovent) • Smooth muscle relaxant of larger, proximal airways • Onset of action within a few minutes • Peak effects in roughly 20-30 minutes • Duration of effects up to 4-6 hours • Has been demonstrated to have an additive effect with albuterol • Common side effects may include: • Dryness of mouth and airway • Decreased secretions • Tremors

5. Bronchodilators • Albuterol and atrovent may be combined into one medication and may provide an enhanced bronchodilation over using one or the other alone • Examples: • Combivent comes in a metered dose inhaler • Duoneb comes as a liquid solution to be used in a nebulizer

6. Inhaled Steroids • Flovent • Pulmocort • Decreases airway secretions • Decreases inflammation • May be immunosuppressive in large doses, over time • Vasoconstricts • Increases the effectiveness of bronchodilators • Onset of action roughly 2-3 hours • Duration of action 8-12 hours

7. Other • Racemic Epinephrine • Primarily used to increase the internal diameter of airways through vasoconstriction • Also a potent, short-acting bronchodilator • Onset of action within a few minutes • Peak effects within 15 minutes • Duration of action roughly 2 hrs • Side effects may include: • Similar to high-dose albuterol • Repeated doses may begin to produce “rebound” effects

8. Other • Pulmozyme • Used to break DNA strands found in thick mucus, thereby thinning the secretions for easier removal. • Side effects include: • Sore throat and/or vocal cords • Voice hoarseness • Rash or itchiness • Conjunctivitis (weepy, itchy, or gritty eyes) • Chest pain • Is corrosive to some materials found in ventilators and requires special filters on the exhalation side of the circuit.

9. Nitric Oxide • N-O • It is found throughout the body and is, among other many other things, responsible for vascular smooth muscle relaxation. • When inhaled it travels to any open alveoli and then relaxes the blood vessels supplying those alveoli. • It may decrease the severity of pulmonary hypertension in some patients. • Very short half-life (a few seconds) • Unstable. It reacts readily with oxygen to produce NO2 (the poisonous gas nitrogen dioxide) and binds with oxyhemoglobin to produce methemeglobin (metHb). The effects of metHb are similar to those of carbon monoxide in the blood. • Dosages are in parts per million (ppm). • 20ppm is generally the starting dose, then is slowly weaned down after the FiO2 reaches 60% or less. • No clinically significant side effects have been demonstrated at the currently recommended dosages. • Rebound pulmonary vasoconstriction may be a problem when weaning, but may be counteracted with an increase in FiO2.

10. Helium-Oxygen Mixture • Helium-Oxygen (Heliox) starts out from the tank 80% He and 20% O2. • This is NOT the 100% helium used to fill party balloons • Breathing 100% helium has been known to cause neurologic damage from asphyxia • Oxygen is bled into the system to achieve the desired FiO2. • Helium, being the second lightest element known and being relatively inert, is ideal for decreasing the work of breathing. • Breathing helium reduces the airways resistance and may allow more tidal volume at any given ventilating pressure. • It can be delivered through a mask, CPAP prongs, or through a ventilator. • Clinical uses include: • Croup • Asthma • Lung tumors • ARDS, RDS, and other inflammatory lung processes • Tracheal and bronchial stenosis

11. Supplemental Nitrogen • Supplemental nitrogen may be used to lower the FiO2 below 21% when there is excessive blood flow to the lungs, creating conditions favoring pulmonary vascular congestion. • Primarily used in the PICU for certain cardiac heart diseases pre and/or post operatively. • The pulmonary vasculature constricts in response to a low PaO2. Sometimes using less than 21% oxygen is needed to achieve therapeutic efficacy. • Some of the early (1950’s) neonatal units used supplemental nitrogen to lower the FiO2 below 21% to reduce the harmful side effects of oxygen in premature neonates. There has been a resurgence in the interest in this therapy for those premature infants that still may be at risk for oxygen toxicity while breathing room air.

12. Supplemental Oxygen • A highly reactive molecule needed for many biological reactions • Oxygen may only be utilized if there are adequate amounts of anti-oxidants to counteract its potentially toxic metabolites…extremely premature neonates do not appear to have developed an adequate antioxidant system. This system develops after 32-34 weeks gestation • Inadequate and excessive amounts of oxygen produce toxic metabolites which damage cells • An “all things in moderation” strategy must be used to maintain oxygen saturations within normal physiologic levels, which has yet to be determined • Fetal cells are genetically designed for oxygen saturations of 30-80%, anything more or less than that may cause damage to the cells, especially within the first few weeks of life. • Unfortunately, greater than 70% oxygen saturation may be needed for extrauterine life and weight gain • Oxygen and its metabolites have been implicated as the root cause of nearly all the common mortality and morbidity seen in premature neonates.

13. Transcutaneous CO2/O2 Monitoring • A modified set of blood gas electrodes are placed on the skin and tissue measurements are obtained. • The site is warmed: • Typically 41-42* C • The warming increases perfusion to the site through vasodilation of the local blood supply • Gases diffuse from the blood vessels and tissues through the skin and into the electrode for measurement • They are perfusion-dependent in their accuracy • Placing the warmed electrode on the skin of a patient with poor perfusion may cause local tissue damage • The accuracy of the reading is severely compromised • They should only be placed on areas where there is an abundance of soft tissue • Do not place on a bony area • They should not be placed near an infection site • The warming of this area may increase the metabolism of damaged tissue creating further damage • The accuracy of the reading is severely compromised

14. End-tidal CO2 monitoring • Not often used in the NICU, but common in the PICU, OR, and adult ICUs • May also be used as part of a multi-channel pneumogram to assess the presence of gas exchange compared to chest wall movement • Exhaled gases are analyzed for the presence of CO2 • In larger patients, gives a relatively accurate, breath-by-breath measurement of CO2 • May be used for ventilator management and monitoring blood gas status during a surgical procedure

15. Pulse Oximeters • Work on the principle that hemoglobin bound with oxygen will reflect light differently than hemoglobin without oxygen bound to it. • A high-intensity light is emitted through the tissues and then read by a receiver on the other side of the appendage (ear, finger, wrist, etc.) • The percentage of hemoglobin bound to oxygen is compared to hemoglobin without and then calculated as a percentage (93%, 98%, etc.) • Does not recognize the difference between normal oxyhemoglobin, met-hemoglobin, and carbon monoxide-hemoglobin • Accuracy may vary significantly depending upon: • Skin pigments, bilirubin, body art, finger nail polish, etc. • Certain dye-containing medications • Abnormal hemoglobins (including fetal hemoglobin) • Ability to “find” the pulse • Ambient light • Degree of oxygen desaturation • Generally not accurate below 85% unless specifically calibrated for low oxygen saturations, which most are not. Documentation of oxygen saturations below 85% should be documented with the presence of a skin color change or not.