Nitrious Oxide

Learning Objectives

• Summarize the conditions in which antianxiety drugs may be prescribed.

• Discuss intravenous sedation and its use in dentistry.

• Discuss general anesthesia and its use in dentistry.

• List the four stages of anesthesia and the levels of consciousness it produces.

• Describe how mind-body medicine is applied to dentistry.

• Explain the necessity of documenting the type of anesthesia and pain control used in a dental procedure.

Inhalation Sedation

• Nitrous Oxide/Oxygen (N₂O/O₂)

  • A combination of gases inhaled to help eliminate fear and to aid relaxation.

Effects of Nitrous Oxide

• Nonaddictive.

• Rapid onset, with minimal side effects.

• Recovery is rapid.

• Produces Stage I anesthesia.

• Dulls the perception of pain.

Advantages of Nitrous Oxide Use

• Administration

  • Simple and easily managed; does not require the services of an anesthetist.

• Safety

  • Excellent safety record with minimal side effects.

• Patient Condition

  • Patient remains awake.

  • Recovery is rapid.

  • Can be used with patients of all ages.

Disadvantages of Nitrous Oxide/Oxygen Use

• Some patients may experience nausea or vertigo.

• Patients with behavioral problems may react negatively and exhibit problematic behavior.

Medical Considerations for N₂O Use

• Contraindications

  • Chronic Obstructive Pulmonary Disease (COPD): interferes with the stimulus to breathe.

  • Cardiac diseases: may increase arterial pressure.

  • Pregnancy: especially during the first trimester.

  • Upper respiratory infections: may have problems inhaling through the nose.

  • Psychiatric disorders and drug dependency: potential to cause hallucinations.

  • Middle ear disturbances: may lead to increased pressure.

  • Critically ill patients: risk of B12 deficiency/anemia.

Equipment of Nitrous Oxide System

• Cylinders

  • Gases are stored in steel cylinders colored green for oxygen and blue for N₂O.

  • Nitrous oxide machines can be portable or integrated into dental units.

  • Control valves manage the gas flow rates.

  • Flow meters indicate the rate at which gases are dispensed.

  • Gases mix in a reservoir bag that the patient uses for breathing.

Gas Hose and Masks

• Gas Hose

  • Carries gases from the reservoir bag to the mask or nosepiece.

• Masks

  • Available in sizes for both adults and children.

  • Nosepiece enables patients to breathe the gases.

Patient Assessment and Monitoring

• Patient History

  • Always review the patient's medical history prior to N₂O/O₂ administration as sedative effects may enhance the impacts of medications.

• Vital Signs Monitoring

  • Obtain and record blood pressure, pulse, and respiration before, during, and after administration.

  • Preoperative readings establish a baseline for comparison.

  • Postoperative readings check the patient's recovery and identify adverse effects.

Patient Education for Inhalation Sedation

• Explain the procedure of administering the gases.

• Describe the use of the mask and the significance of nasal breathing.

• Clarify the sensations that the patient will experience.

• Provide reassurance to the patient.

Administration of Nitrous Oxide

• Start with 100% oxygen while determining the patient’s tidal volume.

• Gradually titrate the nitrous oxide until achieving the desired effects.

• Patients should refrain from talking or mouth-breathing during the procedure.

• Conclude N₂O/O₂ analgesia with 100% O₂ administration for 3 to 5 minutes.

• Record postoperative vital signs and compare with preoperative levels.

Safety Work Practices for the Clinical Team

• Nitrous oxide should solely be used for patient treatment, not for recreational purposes.

• Hazard Reduction

  • Implement scavenger systems.

  • Use well-fitting patient masks.

  • Discourage patient talking to minimize gas escape.

  • Vent excess gas outside the building.

  • Regularly inspect equipment and hoses for leaks.

  • Utilize a monitoring badge system to assess nitrous oxide exposure for staff.

Antianxiety Agents

• Sedatives are preferred for managing anxiety in patients.

• Criteria for Use

  • Indicated for very nervous patients or long/difficult procedures.

  • Utilized in mentally challenged patients.

  • Applicable for very young children undergoing extensive treatment.

Intravenous (IV) Sedation

• Antianxiety drugs are administered via IV throughout procedures at a slower rate to allow for deeper Stage I analgesia.

• Physiological Monitoring

  • Measurements of consciousness, respiratory function, oximetry, blood pressure, heart rate, and cardiac rhythm are recorded every 15 minutes.

General Anesthesia

• A controlled state of unconsciousness inducing a loss of protective reflexes results in Stage III general anesthesia.

• Pharmacological Composition

  • Often involves a combination of gases including N₂O/O₂, halothane or enflurane, alongside IV agents like thiopental sodium and methohexital sodium.

Four Stages of Anesthesia

• Stage I: Analgesia

• Stage II: Excitement

• Stage III: General Anesthesia

• Stage IV: Respiratory Failure or Cardiac Arrest

Patient Preparation

• Preoperative Procedures

  • Conduct a thorough physical examination.

  • Order laboratory tests as needed.

  • Secure the signature of the patient or legal guardian on a consent form.

Patient Education Pre-Anesthesia

• Review the procedure and outline potential risks with the patient.

• Emphasize that the patient must refrain from eating or drinking for 8 to 12 hours prior to general anesthesia.

Patient Recovery

• Post-procedure monitoring is essential until normal reflexes return.

• The patient should not be left alone during recovery from anesthesia.

Mind-Body Medicine

• Techniques aimed at reducing anxiety and pain without pharmacological intervention include:

  • Distraction (e.g., music, visual entertainment).

  • Relaxation techniques, guided techniques, deep breathing, biofeedback, hypnosis, acupuncture.

Documentation of Anesthesia and Pain Control

• Important information to document includes:

  • Patient’s medical history review.

  • Preoperative and postoperative vital signs.

  • Patient’s tidal volume if inhalation sedation is applied.

  • Times documenting when anesthesia commenced and concluded.

  • Peak concentration administered during the procedure.

  • Total minutes required for postoperative recovery.

  • Any adverse events or patient complaints.

Nitrous Oxide (N₂O) Characteristics

• N₂O is a liquid that pressurizes to form a gas, stored in blue cylinders.

• N₂O has a sweet odor and no taste, does not chemically combine with body substances.

• Explosions can occur from grease or oil on valves; while not flammable, N₂O is combustible.

• Risk of emotional addiction exists; vapor pressure is undetectable until tanks nearly empty.

• Tank pressure ranges from 750-900 psi.

• Maximum dosage limit is 70%, optimal concentration is between 35%-40%.

Oxygen (O₂) Characteristics

• Oxygen is a gas stored in green cylinders; can also cause explosions involving grease or oil.

• O₂ is flammable; full cylinder pressure is 2000 psi, with minimum amount of 30% for safety in procedures.

• 100% oxygen is utilized to manage emergency situations.

  • The "Oxygen Failsafe" prevents N₂O flow unless O₂ is flowing, enhancing patient safety.

Equipment Overview

• Flow Meters

  • Indicate the amount of gas delivered to the patient.

• Control Knob

  • Power switch for the system.

• Emergency O₂ Hook-Up

  • Provides oxygen supply in case of emergencies.

• O₂ Flush Button

  • Rapidly fills the reservoir bag with oxygen to dilute N₂O.

• Room Air Intake

  • Supplies room air if the machinery malfunctions.

• Stand

  • Holds the N₂O/O₂ equipment in the proper position.

• Tubing

  • Transfers gas from tanks through flow meters to the patient.

• Nose Mask (Nasal Hood)

  • Should be sterilized between patients. It must fit properly on the patient's nose to facilitate breathing.

• Reservoir Bag

  • Gas mixture is visible in this bag and aids in monitoring the patient's respiration.

Definitions of Key Terms

• Analgesia: The state of being pain-free without loss of consciousness.

• Sedation: Calming a nervous patient through drugs without inducing unconsciousness.

• Anesthesia: Temporary loss of feeling or sensation through drug use.

• Local Anesthesia: Affects specific areas only.

• General Anesthesia: Affects the entire body with complete loss of consciousness.

Stages of General Anesthesia

• Stage 1: Analgesia: Patient is relaxed yet fully conscious. Experiences a sense of euphoria and reduced pain.

• Stage 2: Excitement: Patient is less aware of surroundings; may become excited and unmanageable.

• Stage 3: General Anesthesia: Gag and cough reflex suppressed; throat packs necessary; no pain or sensation.

• Stage 4: Respiratory failure or cardiac arrest: Lung and heart functions slow dramatically; prompt reversal necessary to avoid fatality.

Planes of Analgesia

• Plane 1: Vital signs normal; patient is relaxed and can follow directions. Eyes are responsive to operator actions.

• Plane 2: Vital signs normal; relaxed state characterized by tingling and slight intoxication without losing awareness.

• Plane 3: Vital signs maintained; patient becomes drowsy and begins to experience nausea. Awareness diminished.

Equipment Summary

• Flow meters, control knobs, emergency oxygen hook-ups, and O₂ flush systems play critical roles in maintaining safety and efficacy in administering nitrous oxide and oxygen. Proper maintenance and sterilization protocols for all equipment, including masks and tubing, are essential for patient safety.