Phy Eval, Intro Oral IM, IV - Lecture 10: Patient Evaluation and Intro to Sedation Types
Objectives of the physical evaluation
There is no such thing as truly “minor” anesthesia; even oral sedation can have adverse events if the endpoint is overshot. The ultimate goal is a live patient at the end of the procedure.
Objectives of the evaluation include:
Establish a relationship with the patient or guardian.
Familiarize with coexisting medical conditions to avoid jeopardizing them.
Develop an anesthetic plan (local + possible sedation or general anesthesia).
Obtain informed consent for deeper sedation beyond local anesthesia.
Note on consent terminology:
Implied consent covers typical local anesthesia and nitrous oxide in many settings.
For moderate/severe sedation, informed consent is required; avoid the term “medical clearance” when talking to physicians.
History and organ-system review
Obtain a thorough patient history with an organ-system focus (not just a list of diseases):
Cardiovascular system: assess functional reserve and exercise tolerance; e.g., ability to walk 2 blocks without undue dyspnea, fatigue, chest pain, or to climb stairs (METs assessment).
Respiratory system: history of asthma, COPD, cystic fibrosis; triggers and relief factors; assess for airway risk.
Liver and kidneys: assess hepatic/renal function and implications for drug metabolism and excretion.
Neurologic: seizure disorders, neurological status.
Endocrine: thyroid disease, diabetes (including insulin dependence) and how fasting or sedation might affect management.
Medication history:
Review all prescribed drugs, nonprescription drugs, herbal supplements.
Consider potential drug interactions with sedative agents and with local anesthesia.
Consider weight/disease severity implications of each med.
Practical tip: use a drug reference (e.g., Epocrates) to check interactions and off-label uses; carry a personal resource if needed.
Anesthesia/sedation history:
Assess sensitivity to sedatives (e.g., very sensitive vs. tolerant to alcohol).
Screen for airway problems, obstructive sleep apnea, prior anesthesia experiences and recovery (including PONV).
Evaluate post-op nausea/vomiting history related to prior opioid analgesics.
Important note on drug interactions with coexisting diseases and with local anesthesia.
In-office physical examination and airway assessment
General appearance and function:
Observe overall health status, ability to walk, evident distress, obesity or cachexia, etc.
Auscultate heart and lungs; inspect for signs of poor perfusion or respiratory distress.
Airway assessment (critical for sedation planning):
Snoring or airway obstruction signs; assess extensibility of jaw/neck; retrognathia; mandible size.
Evaluate mouth opening and the ability to protrude mandible.
Assess neck extension, ability to extend head, and ability to tolerate bag-valve-mask ventilation if needed.
Practical checks (noninvasive): open mouth widely; watch tongue size relative to palate; look at airway anatomy (e.g., if only a large tongue is visible, airway may be compromised).
Consider planar implications for bag-mask ventilation during potential respiratory compromise.
Vital signs and monitoring:
Record age, gender, heart rate, respiratory rate, blood pressure; consider oxygen saturation with a portable finger pulse oximeter.
Use monitors to track vital signs during sedation as indicated.
Medical consultation and ASA classification
Indications for a medical consultation:
When the medical history is unclear or poorly controlled; complex co-morbidities; bleeding disorders; poorly controlled systemic diseases; or when planning sedation beyond minimal levels.
Consults can be of two types:
Opinion-type consult: e.g., contact cardiology to understand a heart murmur or implanted devices; clarify what is needed from the physician.
Treatment-type consult: e.g., ask hematology about desmopressin for Willebrand disease before extraction; insulin management guidance for a planned procedure.
Who gets a consult:
Unclear or poorly controlled medical history; need to modify medications for the procedure; significant cardiac, bleeding, or endocrine concerns (e.g., insulin-dependent diabetes).
Documentation and communication:
Describe dentistry and planned sedation in lay terms for physicians to understand.
Request clarification of medical history, ability to tolerate stress, and any medical contraindications to planned care.
Request pertinent test results (e.g., echocardiogram, INR, HbA1c) to inform risk assessment.
Ensure the physician is aware that dentistry is peripheral but not risk-free; close the loop with documented communication.
Laboratory studies and tests:
Tests are driven by coexisting diseases (e.g., INR for anticoagulation, HbA1c for diabetes).
ASA classification (American Society of Anesthesiologists):
$ASA~I$: normal healthy patient with no medical problems.
$ASA~II$: mild systemic disease; examples include well-controlled asthma, hypertension, diabetes without systemic impact, smoker, well-controlled seizure disorder, phobias, uncomplicated Down syndrome, etc.
$ASA~III$: severe systemic disease that limits activity but is not incapacitating; examples include insulin-dependent diabetes with vascular changes, stable angina, poorly controlled hypertension, poor exercise tolerance.
$ASA~IV$: incapacitating systemic disease that is a constant threat to life (e.g., unstable angina, recent major cardiac events within a short timeframe).
$ASA~V$: patient not expected to survive 24 hours with or without surgery (e.g., terminal illness in a surgical context).
$ASA~VI$: organ donor (brain dead) – typically not managed in routine dental sedation.
Note: modern practice often emphasizes $ASA~I$–$III$ for many dental procedures; $ASA~IV$ patients require careful consideration and clear medical stabilization.
Informed consent:
Discuss the dental plan and planned sedation; disclose alternatives and the risks of the proposed approach; obtain signed consent.
For deeper sedation, discuss more serious complications (e.g., airway compromise, allergic reactions, breathing problems) in proportion to the level of sedation.
For nitrous oxide, oral sedation, or IV sedation, discuss specific risks relevant to the chosen modality and ensuring understanding by the patient or guardian.
Nitrous oxide sedation: indications and contraindications
Indications:
Anxiety control, reduction of gag reflex, and enhancement of patient comfort during procedures where local anesthesia is used.
Absolute contraindications:
Inability to breathe through the nose (nasal mask needs nasal breathing to work).
Acute pulmonary disease or illness at the time of treatment.
Active psychosis or conditions where the patient cannot communicate effectively.
Gas bubble in the eye or ongoing intravitreal gas (risk of visual disturbance).
Otitis media infection without treatment is context-dependent, but active ear infections complicate use.
Relative contraindications and cautions:
Chronic pulmonary disease (asthma, emphysema, COPD) – use caution.
Pregnancy, particularly in first trimester; generally avoid if possible.
CNS depressants and medications that interact with nitrous oxide; titrate to effect rather than fixed concentrations (avoid excessive exposure).
Methylenetetrahydrofolate reductase (MTHFR) deficiency with prolonged exposure (>approximately ) may cause adverse effects due to combined effects on methionine synthesis.
Claustrophobia, extreme anxiety about wearing a face mask, or inability to communicate during titration.
Practical considerations:
Use titration, not a fixed concentration (e.g., avoid just going to nitrous oxide by default).
Monitor for respiratory compromise and ensure patient communication throughout.
Nasal-pulmonary system review for nitrous oxide suitability:
Confirm ability to breathe through the nose; assess any nasal obstruction or nasal mask tolerance.
Evaluate current medications and psychiatric history (avoid giving nitrous oxide to patients with active psychosis).
Special notes:
Avoid nitrous oxide if gas bubbles are present in the eye; avoid in active intratemporal middle ear infections.
For autistic or other special cases, parental concerns about MTHFR deficiency or other hereditary conditions should be discussed with caution.
Oral sedation: introduction and key concepts
Use: primarily for anxiety control; can offer antiemetic effects.
Advantages:
High patient acceptance due to pill form; popular marketing claims (e.g., “no needles, no shots”).
Low cost; easy premedication with minimal equipment.
For minimal sedation, no special training beyond dental school is required in many states (California examples noted).
Disadvantages:
Reliance on patient compliance with pre- and post-procedure instructions.
Prolonged and unpredictable onset due to variable absorption (latency period).
Inability to titrate to effect once given; limited or no reversibility depending on the drug used.
Prolonged duration of action requiring escort home.
Pharmacology and absorption considerations:
Absorption is greatest in the small intestine; lipid-soluble drugs are absorbed more readily; pH and pKa influence absorption.
First-pass metabolism in the liver can inactivate a portion of the drug before it reaches systemic circulation.
Gastric emptying time affects onset; delays occur with obesity, anxiety, diabetes, or large meals; liquids empty faster (~) than mixed meals (~).
Best practice is to administer on an empty stomach with water to accelerate onset (no food delay);
Liquids: ~; mixed meals: ~ completion prior to absorption.
For some drugs, a portion may be inactivated by first-pass metabolism depending on formulation.
Practical considerations:
Do not rely on oral meds for rapid titration; nurse/guardian must escort the patient home due to prolonged effects.
Discharge planning should include a responsible adult to escort the patient home.
Recommended dosage control: avoid patients taking more than prescribed; some may under-dose due to sensitivity or fear, others may over-dose seeking greater relief.
The use of water with each dose helps with gastric transit and onset.
Monitoring and deposits:
Even with minimal sedation, monitor and document patient response and vital signs; individual variability is common.
Parenteral sedation: introduction to IM and IV routes
Intramuscular (IM) sedation (conscious sedation in California):
Used for noncooperative adults and pediatric patients when cooperation is limited.
Rapid onset (approx. ) with maximum clinical effect around ; absorption is more predictable due to consistent muscle perfusion.
Advantages: does not require patient cooperation for administration; reliable start for uncooperative patients.
Disadvantages: no true titration after injection; drug reversibility depends on agent; injection induces pain and potential morbidity; need to manage needle risks.
Injection sites:
Vastus lateralis (lateral thigh) – most common in children.
Deltoid – used in older children (>5–6 years).
Gluteal muscle is generally avoided due to accessibility issues.
Injection technique (practical tips):
Prepare with gloves; pull skin taut (do not pinch) to prevent backflow.
Insert needle at ~90° angle; inject quickly like a dart; release skin after injection to seal the track and prevent leakage.
Needle length: at least 1 inch to reach muscle; longer needles may be necessary for obese patients.
Complications and safety:
Risk of nerve injury if injection is not in the correct location; risk of hematoma or abscess if sterile technique is not followed; risk of sloughing if incorrect tissue is injected.
Improper injection into subcutaneous tissue may result in suboptimal sedation.
Intravenous (IV) sedation:
Indications: for cooperative patients needing deeper sedation or longer procedures; allows rapid adjustments and titration to effect; readily reversible with appropriate agents.
Advantages:
Rapid onset with precise dose control; quick titration to maintain sedation; ability to use reversal agents if available.
Shorter recovery time due to controlled drug levels and predictable clearance when using short-acting agents.
IV access allows immediate administration of emergency medications if needed.
Disadvantages and risks:
Requires IV access, which some patients may resist; higher equipment needs and cost; potential venous injury or tissue damage at injection site;
Requires more training and monitoring; patient escort remains necessary after discharge.
General considerations for both IM and IV sedation:
The patient must have an escort home after any sedation beyond minimal levels.
All sedation beyond nitrous oxide requires appropriate monitoring and equipment.
In case of IV sedation, more extensive monitoring is typical and may require additional staff or facilities.
General considerations: ethics, documentation, and real-world practice
The overarching ethical aim is to minimize risk and maximize patient safety; dentistry is often peripheral and less invasive, but sedation adds systemic risk.
Documentation is critical: evidence of history, airway assessment, vital signs, ASA classification, consent, and communication with the patient’s physician when a consult is performed.
In practice, clinicians often balance the need for adequate anxiety control with medical safety, choosing the lowest-risk approach capable of achieving treatment goals.
Practical notes:
Be prepared to adjust plans based on medical stability; consult when stability is uncertain.
Maintain clear lay-language descriptions when communicating with physicians during consultations.
Keep in mind that different states have varying requirements for training and monitoring for oral only, nitrous, or deeper sedation.
Practical references and tips gleaned from the lecture
Be prepared to discuss the specific condition and treatment plan with a physician; avoid asking for a blanket “clearance” and instead seek medical stability and suitability for planned care.
Use equipment and resources available in your setting (e.g., Epocrates or similar drug interaction tools) to assess potential interactions with sedative regimens.
For nitrous oxide, titration is essential; avoid fixed-dose approaches (e.g., not simply up to 50% automatically).
For oral sedation, advise patients on fasting status, absence of heavy meals, and water intake; emphasize the need for an escort post-procedure.
For IM injections, ensure proper technique to maximize efficacy and minimize tissue injury and pain; use appropriate needle length; avoid injection into subcutaneous tissue.
For IV sedation, prepare to manage airway and have reversal/emergency medications available; ensure staff and monitoring requirements are met; weigh the cost and logistics of IV sedation against patient needs.
Always include a plan for post-procedure follow-up and possible complications in the informed consent and postoperative instructions.
Key numerical references mentioned in the lecture
Onset and duration for IM sedation: approximately onset; maximum effect around .
Nitrous oxide titration example: avoid fixed high concentrations; titrate to effect (not a fixed 50 ext{%}).
Gastric emptying times for oral medications:
Liquids: roughly to pass through the stomach.
Mixed meals: roughly to pass through the stomach.
Gastric emptying/absorption considerations:
Delayed gastric emptying occurs with obesity, anxiety, and type 1 diabetes; affects onset and absorption.
MTHFR deficiency and nitrous oxide exposure:
Prolonged exposure (approximately >) may pose additional risks due to effects on methionine synthesis pathways.
Needle length for IM injections:
At least to ensure intramuscular deposition.
Comparative duration and titration advantages of IV sedation:
IV sedation provides rapid onset, titratable dosing, and quicker recovery once infusion stops, compared to longer and less controllable oral or IM regimens.
If you want, I can format these notes differently (e.g., by system or by sedation modality) or expand any section with more detailed bullet points for targeted exam prep.