OSA/PONV Flashcards
OSA
Screening score
Screening questions
How to Use
STOP-BANG Screening for OSA
Screening Questions
Snoring: loud snoring
Tiredness: being tired, fatigued, or sleepy during daytime
Observed Apneas: others have observed patient stop breathing during sleep
Pressure: diagnosed with hypertension
BMI: >35
Age: >50
Neck circumference: >40cm
Gender: Male
How to Use
Scoring:
≥3: high risk of having OSA
<3: low risk of having OSA
Sensitivity for various AHI levels:
AHI >15: 93%
AHI >30: 100%
Specificity
AHA >15: 43%
AHA >30: 37%
OSA
Inpatient vs Outpatient Management
Considerations
Inpatient vs Outpatient Management
Insufficient evidence either way
Team discussion needed
Things to consider:
Sleep apnea status
Anatomical and physiologic abnormalities
Status of coexisting diseases
Nature of surgery
Type of anesthesia
Need for postoperative opioids
Patient age
Adequacy of post discharge observation
Capabilities of the outpatient facility: The availability of emergency difficult airway equipment, respiratory care equipment, radiology facilities, clinical laboratory facilities, and a transfer agreement with an inpatient facility should be considered in making this determination
OSA
Preoperative Preparation
Preoperative Preparation
Preoperative initiation of CPAP should be considered, particularly if OSA is severe. For patients who do not respond adequately to CPAP, NIPPV should be considered. In addition, the preoperative use of mandibular advancement devices or oral appliances & preoperative weight loss should be considered.
A patient who has had corrective airway surgery (e.g., uvulopalatopharyngoplasty, surgical mandibular advancement) should be assumed to remain at risk of OSA complications unless a normal sleep study has been obtained & symptoms have not returned.
Remember potentially difficult airway
Things to examine:
Evaluation of the airway
Nasopharyngeal characteristics
Neck circumference
Tonsil size
Tongue volume
OSA
Intraoperative Management
Intraoperative Management
Susceptible to the respiratory depressant & airway effects of sedatives, opioids, & inhaled anesthetics; therefore, the potential for postoperative respiratory compromise should be considered in selecting intraoperative medications.
For superficial procedures → consider local anesthesia or peripheral nerve blocks, with or without moderate sedation.
If possible use Spinal/Epidural over GA
If moderate sedation is used → ventilation should be continuously monitored by capnography or another automated method
Consider administering CPAP or using an oral appliance during sedation to patients previously treated with these modalities
General anesthesia with a secure airway is preferable to deep sedation without a secure airway, particularly for procedures that may mechanically compromise the airway.
Extubation:
Awake if possible
Full reversal
Carried out in the lateral, semiupright, or other nonsupine positions.
OSA
Postoperative Management
Risk factors for post-op Respiratory depression
Post-op Analgesia/Sedation
Oxygenation
Other points
Postoperative Management
Risk factors for post-op Respiratory depression
Severity of the sleep apnea
Systemic opioids
Use of sedatives
Site & invasiveness of surgical procedure
The potential for apnea during rapid eye movement (REM) sleep on the third or fourth postoperative day (i.e., “REM rebound”), as sleep patterns are reestablished.
Post-op Analgesia/Sedation
Consider regional if possible
If epidural post-op, weigh cons/benefits epidural opioids vs local alone
If PCA, avoid continuous background infusion
Consider multimodal analgesia (NSAIDs, tylenol, etc)
Caution using any sedatives
Oxygenation
Use supplemental oxygen
Use CPAP/BiPAP if they were on it. Use their own device as it improves compliance
Other Points
Positioning: if possible, place in non-supine positions
Hospitalized patients who are at ↑ risk of respiratory compromise from OSA should have continuous pulse oximetry monitoring after discharge from the recovery room. Continuous monitoring may be provided in a critical care or stepdown unit, by telemetry on a hospital ward
Frequent or severe airway obstruction or hypoxemia occurs during postoperative monitoring, initiation of nasal CPAP or NIPPV should be considered.
OSA
Perioperative Risk Calculation
Perioperative Risk Calculation
Each category scored out of 3
Add Score A & higher of B or C to get final score.
Score 4 = ↑ risk
Score 5/6 = Significantly ↑ risk__
Postoperative Nausea & Vomiting Guidelines
General Principles
Postoperative Nausea & Vomiting Guidelines
General Principles
All patients should be assessed for risk of PONV
General principles:
Risk reduction
Prophylaxis
Treatment
Multimodal PONV management strategy should take into account:
Patient’s choice
Cost-effectiveness
Preexisting conditions (risk of prolonged QT, Parkinson’s, closed-angle glaucoma, etc)
PONV management is an important part of Enhanced Recovery Pathways
PONV
Identifying Patients at Risk
Scoring system
Other RFs
Risk categories
Identifying Patients at Risk
Apfel Simplified Risk Score for PONV. Risk factors are:
Female Sex
History of PONV or Motion Sickness
Non-smoker
Use of Postoperative Opioids
Number of Apfel risk factors & risk of PONV:
0 = 10%
1 = 20%
2 = 40%
3 = 60%
4 = 80%
Other known risk factors:
Younger age <50
General anesthesia
Use of volatile anesthetics and nitrous oxide
Duration of anesthesia
Type of surgery (cholecystectomy, laparoscopic, gynecological)
Risk categories based on number of risk factors:
Low: 0-1
Medium: 2-3
High: 4 or more
PONV
Reducing Baseline Risk
Reducing Baseline Risk
Avoid general anesthesia by using regional anesthesia
Avoid volatile anesthetics
Avoid nitrous oxide in surgeries >1 hr
Use propofol to induce & maintain anesthesia
Minimize intra- and post-op opioids (regional techniques, multimodal analgesia, α2-agonists)
Adequate hydration
Sugammadex instead of neostigmine for reversal of neuromuscular block
PONV
Prophylaxis Approach
Number of agents to give
Combinations
Prophylaxis Approach
Number of Agents to Give
Low: No prophylaxis
1-2 risk factors: Give 2 medications
>2 risk factors: Give 3 or more medications
Suggested Combination Therapy
Never combine drugs from the same class
Most widely studied are 5-HT3 receptor antagonists or butryphenones + dexamethasone. For example, if giving 2 IV drugs:
Ondansetron 4mg + dexamethasone 4mg
Droperidol 0.625 mg + dexamethasone 4mg
Haldol 1 mg + dexamethasone 4mg
PONV
Therapeutic Options: 5-HT3 Receptor Antagonists
Drug examples
When to administer
AEs
5-HT3 Receptor Antagonists
Specific Drugs
Ondansetron = Gold standard
4 mg IV at the end of case
NNT = 6 for prevention of vomiting & 7 for prevention of nausea
Granisetron
0.35-3 mg (5-20mcg/kg) IV
As effective as ondansetron
Palonosetron
0.075 mg IV
Effective for 24 hours & superior to ondansetron 4mg IV for PONV prevention
Ramosetron
0.3 mg IV
Similar effectiveness to ondansetron
When to Administer
Ondansetron & Granisetron most effective when given at end of surgery
Palonosetron is usually given at the start of surgery
Adverse Events
NNH listed is for Ondansetron
Constipation (NNH = 23)
↑ Liver Enzymes (NNH = 31)
Headache (NNH = 36)
↑ QTc: rare especially for 4mg Ondansetron IV dose
PONV
Therapeutic Options: NK-1 Receptor Antagonists
Drug examples
When to administer
AEs
NK-1 Receptor Antagonists
Aprepitant
40-80mg PO within 3 hours of induction of anesthesia
Routine use not yet established
Appears to be more effective than ondansetron in preventing PONV in the first 24-48 hours
PONV
Therapeutic Options: Corticosteroids
Drug examples
When to administer
AEs
Corticosteroids
Dexamethasone
Prophylactic dose for PONV = 4-8 mg IV
Other beneficial benefits when used in higher doses of 0.1mg/kg or 8 mg IV in adults:
better analgesia
↓ sore throat & muscle pain
↓ difficult falling asleep
Methylprednisolone
40mg IV effective
PONV
Therapeutic Options: Antidopaminergics
Drug examples
When to administer
AEs
Antidopaminergics
Amisulpride
Dopamine D2, D3 receptors antagonist
5 mg IV for treatment of PONV
Droperidol
0.625 mg IV at the end of surgery
Efficacy similar to ondansetron for PONV prophylaxis
NNT = 5 for both nausea & vomiting prevention
QTc prolongation issues:
FDA “black box” restriction 2001; however, doses used for PONV prophylaxis unlikely to ↑ QTc. Studies show equal QTc effects to Ondansetron
Haloperidol
0.5-<2mg IV or IM at the end of surgery
With these low doses, sedation does not occur & cardiac arrhythmias are unlikely
QTc prolongation is possible with Haldol, but studies have not shown higher risk than Ondansetron
Extrapyramidal side effects are rare with one study suggesting 1/806 patients or 0.1%
Perphenazine
5 mg IV
No increase in sedation or drowsiness
Metoclopramide
Conflicting evidence due to prior meta-analysis including fabricated evidence
10 mg IV for PONV prevention
NNT 8-10
Dyskinesia or extrapyramidal symptoms reported at 0.4% (10 mg) and 0.8% (25-50 mg)
Consider if other dopamine antagonists not available
PONV
Therapeutic Options: Antihistamines
Drug examples
When to administer
AEs
Antihistamines
Dimenhydrinate
1mg/kg IV (max 50 mg) is recommended dose
NNT 8 (early postop period) and 5 (late postop period)
Antiemetic effect may be similar to ondansetron but insufficient studies for optimal timing or dose
Promethazine
6.25 mg IV or deep IM injection
FDA Black box warning 2009: risk severe tissue damage/gangrene if arterial injection or injected under the skin (interstitial IV)
