1. To provide rapid-onset (2 to 6 minutes), quickly reversible (2 to 5 minutes) analgesia for 30 minutes or less. Nitrous oxide may be used to relieve pain associated with trauma, renal colic, myocardial infarction, minor surgical procedures, wound care, diagnostic procedures, and reduction of fractures and dislocations.

2. To relieve the anxiety associated with painful conditions and procedures

1. When used for analgesia in the emergency setting (versus anesthesia in the operative setting), the gas mixture should be fixed at 50% nitrous oxide to 50% oxygen. For altitudes above 3500 feet, a 65% nitrous oxide to 35% oxygen mixture is recommended because the lower partial pressure of the nitrous oxide at higher altitudes does not provide adequate analgesia.

2. The patient should always self-administer the gas to prevent oversedation. Therefore, the patient must be cooperative and able to follow instructions. The mask or mouthpiece should never be strapped to or held on the patient’s face.

3. Nitrous oxide causes drowsiness and should not be used in patients with altered levels of consciousness or head injuries, or those who are heavily sedated or intoxicated. Patients who have received opioids should be individually evaluated for suitability before receiving nitrous oxide.

4. Nitrous oxide occasionally causes nausea and vomiting, so caution is indicated with recent ingestion of food or fluids.

5. The gas mixture contains 50% oxygen (35% at high altitude); therefore, it does not supply enough oxygen for patients who have pulmonary edema and may suppress the hypoxic respiratory drive in a patient who has chronic obstructive pulmonary disease.

6. Nitrous oxide collects in dead air spaces and can expand the preexisting pockets of air associated with pneumothorax, otitis media, perforated viscus, bowel obstruction, air embolism, and decompression sickness.

7. Nitrous oxide should not be used during early pregnancy, because it has been associated with fetal defects and spontaneous abortion.

8. A scavenger system to dispose of exhaled gas protects health care providers who administer nitrous oxide. Studies involving operating room and dental personnel have associated long-term exposure to nitrous oxide with psychomotor impairment and congenital malformations, as well as spontaneous abortion in exposed women and sexual partners of exposed men. Possible association with bone marrow suppression, cancer, liver disease, and renal disease has also been reported.

9. A mask is preferred to facilitate disposal of exhaled gas. If the patient is unable to use a mask because of facial trauma or other conditions, a mouthpiece may be used in place of a mask.

10. Nitrous oxide has abuse potential. The unit should be kept in a secure area. A pop-off demand valve is available; the valve can then be locked up with the narcotics.

11. A fail-safe valve should be incorporated into the system to prevent administration of 100% nitrous oxide if the oxygen supply is interrupted.

12. A nurse or physician should be present at all times during nitrous oxide administration in the hospital setting unless institutional policies are in place specifying other qualified personnel who may monitor the patient.

Nitrous oxide and oxygen tanks connected to a blender preset to deliver 50% nitrous oxide and 50% oxygen (65% nitrous oxide and 35% oxygen at altitudes above 3500 feet) with demand valve and scavenger (Figure 176-1). (Units are also available for use in the prehospital environment and for nitrous oxide supplied by pipeline.)

Mask or mouthpiece

Wall suction and suction connection tubing

Pulse oximeter

NOTE: In countries other than the United States, nitrous oxide may be available in a single-tank mixture known as Entonox.

1. Assess and document vital signs.

2. Initiate pulse oximetry monitoring (see Procedure 21).

3. Instruct the patient to do the following:

1. Turn on the nitrous oxide and oxygen tanks by opening the cylinder valves with a wrench. Check that the mixture pressure is within the safe level per manufacturer’s specifications (30 to 35 psi for Nitronox by Matrx Medical, Inc. [1996]). Do not use the unit if the mixture pressure is not within the safe level. Check the pressure of each cylinder, and replace any cylinder with a pressure less than 300 psi (see Procedure 26).

2. Connect the scavenger to the wall suction and turn the suction on. Turn the ball valve lever on the scavenger tube to the ON position. Adjust the suction to 30 to 60 L/min.

3. Attach mask or mouthpiece to the demand valve.

4. Allow the patient to inhale the gas for 3 or 4 minutes before beginning any procedures. Some patients may require up to 6 minutes for adequate induction.

5. Monitor pulse oximetry continuously, and document it frequently (i.e., every 5 minutes) throughout the procedure.

6. As the patient becomes relaxed, he or she will be unable to create an adequate amount of negative pressure to trip the demand valve. This prevents excessive sedation.

7. When the patient drops the mask or mouthpiece, position or hold it so that the exhaled gas can be taken up by the scavenger.

8. Allow the patient to resume gas inhalation when he or she is able to hold the mask or mouthpiece.

9. Nitrous oxide administration is usually limited to a maximum of 30 minutes.

10. Assess and document vital signs and pulse oximetry.

11. When the procedure is completed, turn off the suction and nitrous and oxygen tanks. Clear the lines by blowing forcefully through the small holes on the back of the demand valve until all pressure gauges read zero. If the oxygen line bleeds before the nitrous line, you will not be able to remove the nitrous. Open and close the oxygen line and try again.

12. Monitor pulse oximetry and heart rate for 5 to 15 minutes after procedure.

1. Side effects are unusual but may require termination of nitrous oxide administration. Side effects may include vomiting, shortness of breath, excitement, drowsiness, confusion, and light-headedness.

2. Propping or holding the mask against the patient’s face may result in excessive sedation. The patient must hold the mask to prevent overdosage.

3. Aspiration may occur if the patient vomits with the mask in place.

4. The Nitronox unit has a mixer pressure whistle alarm that sounds if there is a disruption in gas pressures resulting in a low oxygen concentration. Discontinue use immediately and notify the manufacturer (Matrx, 1996).

1. Report immediately any uncomfortable sensations during nitrous oxide use.

2. Keep conversation to a minimum, and exhale into the mask or mouthpiece.

1. Hemodynamic or respiratory instability that requires immediate intervention

2. Refusal of a competent patient

3. Allergy to drug class

1. Intoxicated with central nervous system depressants

2. Neurologically impaired

3. Concurrent shock or myocardial infarction

4. Adrenal insufficiency or long-term steroid use (premedicate with intravenous steroid)

5. Moderate-to-severe liver or renal insufficiency

6. Pregnancy

7. Monoamine oxidase inhibitor use within the previous 2 weeks

8. Any condition that could make intubation difficult (e.g., facial or neck trauma, large tongue, short neck, congenital malformation of upper airway structures)

9. ASA Patient Physical Status Classification greater than Class 2 (Table 177-1)

Oral and nasopharyngeal airways (appropriate size for patient)

Suction equipment

Supplemental oxygen source, oxygen cannula, and mask (appropriate size for patient)

Bag-mask (appropriate size for patient)

Cardiac monitor (if indicated by patient’s condition)

Blood pressure monitoring equipment

Pulse oximeter

Crash cart with defibrillator

Reversal agent(s) for medications to be administered (naloxone, nalmefene, and/or flumazenil)

1. Establish intravenous access (see Procedure 60). Intravenous access must be continuously maintained to provide a method of administering sedatives and initiating corrective action for adverse effects. For other routes of medication administration, you must have the ability to obtain intravenous access immediately (ASA, 2002).

2. Initiate pulse oximetry monitoring (see Procedure 21). Initiate end tidal CO₂, cardiac, and blood pressure monitoring as indicated (see Procedures 24 and 55).

1. ^* Before the administration of sedatives, complete a preanesthesia assessment, with documentation, to include at least the following (ASA, 2002):

2. Assess baseline physiologic status of patient including, but not limited to, the following:

3. Have the following available in the procedure area before the administration of any medications: an emergency cart with defibrillator, suction, airway management devices, and reversal agents for the medications being administered.

4. Have supplemental oxygen and suction immediately available.

5. Establish provisions for backup personnel who are experts in airway management and cardiopulmonary resuscitation in the event that complications arise.

6. Maintain a sedation checklist to complete all requirements and record frequently monitored physiologic parameters. Documentation should include the following (AORN, 2002):

7. Monitor the patient carefully from the administration of the medications until recovery. The nurse monitoring the patient should have no other responsibilities during or after the procedure that will interfere the nurse’s ability to adequately monitor the patient (AORN, 2002; ASA, 2002; ENA & ACEP, 2005).

8. During the procedure, document the following physiologic parameters at regular intervals (usually every 5 to 15 minutes, consult your institutional policy) (ASA, 2002):

9. After the procedure, document the patient’s level of consciousness, vital signs, and pulse oximetry every 15 minutes until he or she has recovered. Recovery is indicated by stable vital signs and oxygen saturation and alert and oriented state (or return to baseline mental status). Before discharge, the patient should be able to sit and ambulate (age appropriate) and tolerate oral fluids (ASA, 2002).

1. Advanced cardiac life support (ACLS)

2. Basic life support (BLS)

3. Training in the recognition of the cardiovascular and respiratory side effects of sedatives as well as the variability of patient response

4. Training in airway management

5. Emergency nursing pediatric course (ENPC) or pediatric advanced life support (PALS) for sedation of children

6. Knowledge of the pharmacology of the medications administered

1. Consider dosage reduction in the elderly and chronically ill.

2. When selecting the medications for a pediatric patient, consider the nature of the procedure (painful or nonpainful), the desired onset and duration of action, and the route of administration. In children, moderate sedation may not be adequate, and deep sedation may be the goal. Careful monitoring is indicated.

1. Respiratory depression or apnea

2. Increase in untoward side effects with the dose and the number of different agents used

3. Paradoxical excitement occasionally caused by some drugs instead of the desired effect

4. Side effects as related to specific drug administered

5. Airway obstruction

6. Cardiopulmonary impairment

1. Stay with a responsible adult for 12 hours after the procedure.

2. Do not drive an automobile or operate dangerous machinery for at least 6 to 12 hours. Children should not climb stairs unassisted, ride bikes, or play on playground equipment.

3. Return to the emergency department or call an ambulance for difficulty in breathing, pale or gray skin, or difficulty arousing.

4. Call the physician if vomiting is persistent and fluids do not stay down.

1. There are no absolute contraindications for TOF monitoring; however, patients with physiologic paralysis or degenerative neuromuscular disorders may not have normal muscle contractions in response to peripheral nerve stimulation.

2. Diaphoresis may impede electrode contact altering the muscle response to stimulation.

3. Low batteries may result in less than desired stimulus magnitude.

4. Significant edema or previous nerve damage may produce an altered muscle response.

5. Administer analgesia before starting TOF testing.

Peripheral nerve stimulator

Two electrodes (pediatric size preferred)

Two lead wires

1. Apply electrodes at the selected site (Figure 178-1 and Table 178-1).

2. Attach the peripheral nerve stimulator leads to electrodes. The negative (black) electrode should be placed most distal when using the ulnar nerve site (UNC, 2005).

3. Turn the peripheral nerve stimulator on and set the mA at 10.

4. Push the TOF button and observe for the expected movement (see Table 178-1). Obtain the baseline TOF level by increasing the threshold (amplitude) by increments of 10 mA (to a maximum of 30) until four distinct muscle contractions are observed. If the expected muscle contractions are not seen at 30 mA, check the connections, electrode placement, electrode moisture, and batteries.

5. After neuromuscular blocking agents (NMBA) are initiated, TOF should be assessed every hour until the desired level of block is obtained and then re-assessed at least every 4 hours and more often if titration is required. See Table 178-2 for TOF responses indicating the degree of neuromuscular blockade present; adequate paralysis is indicated by one or two twitches. Common clinical practice for patients receiving NMBA and sedation is to use 80 mA for ongoing TOF monitoring.

6. Document TOF response indicating number of twitches out of four (i.e., ¼ for one twitch), the site, and the mA used.

1. Skin breakdown (change electrode site daily).

2. Inadequate response to stimulus (low batteries, improper electrode placement, or poor connections [dry electrodes]).

3. If a facial site is used, facial contractions may be distressing to family members.

1. Acute myocardial infarction (AMI) diagnosed by the following:

2. Pulmonary embolism diagnosed by angiography or lung scan, involving obstruction of blood flow to a lobe or multiple segments, with or without unstable hemodynamics

3. Deep vein thrombosis

4. Arterial thrombosis or embolism

5. Occlusion of arteriovenous cannulae

1. Active internal bleeding

2. Recent (within 2 months) cerebrovascular accident or intracranial or intraspinal surgery

3. Intracranial neoplasm

4. Severe uncontrolled hypertension

5. History of allergic reactions to streptokinase (Astra USA, 1994)

1. Previous treatment with streptokinase or exposure to Streptococcus infection in the past 6 months (this could result in the formation of antibodies and create resistance to the drug)

2. Recent (within 10 days) major surgery, obstetrical delivery, or organ biopsy

3. Recent (within 10 days) gastrointestinal bleeding

4. Recent (within 10 days) trauma, including cardiopulmonary resuscitation

5. Recent (within 10 days) puncture of subclavian or internal jugular vessel

6. Hypertension: systolic blood pressure greater than 180 mm Hg or diastolic blood pressure greater than 110 mm Hg

7. High likelihood of left-sided heart thrombus (e.g., mitral stenosis with atrial fibrillation)

8. Subacute bacterial endocarditis

9. Hemostatic defects, including those secondary to severe hepatic or renal disease

10. Pregnancy

11. Age greater than 75 years

12. Cerebrovascular disease

13. Diabetic hemorrhagic retinopathy

14. Septic thrombophlebitis or occluded arteriovenous cannula at a seriously infected site

15. Current treatment with oral anticoagulants

16. Any other condition in which bleeding constitutes a significant hazard or would be particularly difficult to manage because of its location

Streptokinase vial (1,500,000 international units)

Normal saline (NS) or dextrose 5% in water (D₅W) solution for reconstitution, 5 ml NS or D₅W solution for further dilution, 40 to 90 ml

Syringes: two 5 ml and one 50 ml

18-G needles

Catheter plug (also known as click lock, PRN adapter, heparin or saline lock)

Intravenous (IV) infusion pump and tubing

1. Perform a thorough assessment, including:

2. Establish continuous cardiac monitoring (see Procedure 55).

3. Establish IV access with a minimum of two to three sites using 18- to 20-G catheters. The use of a double-lumen peripheral IV catheter may reduce the number of punctures (see Procedure 60).

4. Provide routine AMI care as prescribed, which may include but is not limited to the following (Antman et al., 2004):

NOTE: Heparin, if prescribed, will be given after streptokinase administration. See step 7 under Procedural Steps.

5. Administer pretreatment corticosteroids or diphenhydramine as prescribed.

6. Obtain laboratory studies, including the following:

1. Mix streptokinase for administration. In some institutions, the pharmacy prepares the streptokinase solution.

2. When diluting the 1,500,000 international units infusion bottle (50 ml), as in the AMI dose, follow the same procedure as in step 1a, but after the initial reconstitution, the drug can be further diluted in the same vial with an additional 40 ml of NS or D₅W.

3. Assemble IV tubing. An in-line IV filter size 0.8 micron or larger may be used.

4. Because streptokinase contains no preservatives, it must be reconstituted just before use. It may be stored up to 8 hours at 2° to 8° C (36° to 46° F) if necessary.

5. Because of the limited availability of compatibility information, no other medications should be added to the container of streptokinase.

6. Administer the loading dose and initiate the maintenance dose as outlined in Table 179-1. Note that there is no loading dose for use with AMI.

7. Anticoagulation with heparin sodium may or may not be required after streptokinase administration (Astra USA, 1994). If heparin sodium is used intravenously, a bolus dose is not administered, and the continuous heparin infusion is begun only after the PTT falls to 2 times the normal control value. This can take several hours to occur after the conclusion of the streptokinase infusion. Therefore, the PTT should be monitored every 2 hours to determine when it falls in that range. Subcutaneous heparin may be administered in lieu of IV heparin (GUSTO, 1993).

1. Monitor cardiac rhythm and neurologic status continuously.

2. Monitor patient for signs and symptoms of allergic response, which can vary from a low-grade fever to an anaphylactic reaction. For a mild-to-moderate reaction, the physician may prescribe a corticosteroid and an antihistamine, but the streptokinase infusion may be continued. For a severe allergic reaction, the streptokinase infusion should be stopped and anaphylaxis treatment initiated.

3. Assess and document the vital signs every 5 to 10 minutes during streptokinase infusion. Be alert for a precipitous drop in blood pressure. Decrease the rate of streptokinase infusion if hypotension occurs. Hypotension may require volume replacement, pressor therapy, or both.

4. Monitor and document clinical signs of reperfusion, which include cardiac arrhythmias, resolution of chest pain, and normalization of the ST segments. The arrhythmias seen are the same as those seen in many patients having an MI and may include ventricular tachycardia, ventricular fibrillation, sinus bradycardia, accelerated idioventricular rhythm, and heart block. Any arrhythmias that occur are treated following Advanced Cardiac Life Support (ACLS) guidelines.

5. Assess for signs of bleeding complications and coronary artery reocclusion (e.g., recurrence of chest pain or ST segment elevation) every 15 minutes during the infusion and every 2 hours thereafter until 2 hours after the heparin is discontinued.

6. Document the time the chest pain resolves and the time the streptokinase infusion ends.

7. Monitor the PTT every 2 hours. When the PTT falls to less than two times the normal control, a continuous heparin infusion may be initiated.

8. Institute thrombolytic bleeding precautions, which include the following:

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