Anaesthesia for Obs Pt
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Transcript of Anaesthesia for Obs Pt
Anaesthesia for Obstetric Patient
CHALLENGESAltered physiologyPresence of fetus and gravid
uterusAortocaval compression Reflux and possible aspiration
of gastric contents Intubation difficulties Increased oxygen consumption
BLOOD AND CIRCULATORY CHANGES - - Heart rate: ↑ 15% - Stroke volume : ↑ 35%- Cardiac output : ↑ 30-40% - Blood volume : ↑ 35-40%
- Red cell : ↑ 30% , but - plasma volume : ↑ 50% physiological
anaemia
- Pain : ↑ SV and CO 40%
Anaesthetic implications1. High cardiac output Presence of systemic or pulmonary
hypertension, severe cardiac disease may induce cardiac failure and APO. May be obtunded by RA.
2. Venous distension Due to back pressure to the azygos and
epidural veins by the gravid uterus. Decrease spinal LA requirement and
increase risk of bloody tap.
Anaesthetic implications3. Aortocaval compression Due to compression of aorta and IVC by the
fetus causing ↓VR and CO. Clinical features (may be masked ↓ GA/RA)
Symptomatic : maternal SOB and dizziness, Occult : reduced placental flow, fetal
hypoxia Relieved by lateral tilt or pelvic wedge
RESPIRATORY CHANGESAnatomy Engorged airway
apparatus: nose, vocal cords, arytenoids
Lung volumesVT, MV, RR ↑- due to ↑O2 consumption and CO2
productionFRC, ERV ,RV ↓- due to upwards diaphragmatic
displacementIC ↑ , VC no changes
RESPIRATORY CHANGES
Anaesthetic implications1. Functional Residual Capacity ↓:
Smaller O2 reservoir, high O2 consumption causing rapid desaturation.
Mandatory to preoxygenate.
2. Engorged airway: Difficulty with laryngoscopy and tracheal
intubation. Compounded with large breast, ↑weight and short neck. Use short handle.
Airway obstruction is more likely to occur during sedation and anaesthesia.
Oral mucosa easily traumatised.
GASTROINTESTINAL CHANGES↑IAP, ↑gastric volume and acidity.
pH<2.5 with volume 20-25mls ~ Mendelson’s syndrome
↓LOS tone, gastric and intestinal mobilityDelayed gastric emptying in active phase of labour. Increase risk of aspiration
Anaesthetic implications:Neutralisation of gastric acid and RSI with cricoid pressure
(for GA) are mandatory(Sodium citrate, H2 antagonist)
PREOPERATIVE ASSESSMENTHistory- Age, parity, gestation period- Pregnancy complication- Fasting period- Medical, surgical and anaesthetic history- Allergies and medication history- Indication - Discussion and counselling on anaesthetic
technique - Consent
Physical examination
Airway assessmentCardiorespiratory
systemLumbar spine
InvestigationFBCRenal profileCoagulation profileGSH 2 unit PC
PREOPERATIVE ASSESSMENT
General preparationElective caseFast from 12
midnightOral Ranitidine
150mg ON and OM0.3M 30ml Na
citrate on OT call
Emergency caseIV Ranitidine 50mg
stat0.3M 30ml Na
citrate 30 min before op
IV Metoclopramide 10mg at induction
GA Advantages Shorter induction time Lower failure rate Better CVS control Rapid control of convulsion in
eclamptic pt Pt cooperation not required
Disadvantages Difficult airway management Risk of regurgitation and aspiration Awareness Stress response on
induction/reversal PONV Inadequate analgesia post op Hangover effect
RAAdvantages Avoid problems related to
GA Awake patient Effective analgesia
Disadvantages Sympathetic blockade Inadequate/failed block PDPH LA toxicity: inadvertent IV or
intrathecal injection Complications of RA –
epidural abscess, haematoma
REGIONAL ANAESTHESIAContraindication- Patient refusal- Local/systemic
infection- Hypovolaemic state- Fixed cardiac output
state- Coagulopathy- Unskilled/
unsupervised operator
Choices:Spinal/ Epidural/ CSELocal protocol
Post RA:- Left lateral tilt - Oxygen supplement- Check blockade
level :T4- Monitor BP, PR, RR,
SpO2
GENERAL ANAESTHESIAWhen?- RA contraindicated- RA potentially
dangerous- RA takes long time to
be established- RA inadequate block
Preparation- Drugs to be prepared:
- anaesthetics - resuscitation
- Airway device: airways, ETT & various sizes of laryngoscope blades
- Airway adjuncts: to be kept nearby
- Standard monitoring- Reliable IV access- Surgeon in OT
GENERAL ANAESTHESIAINDUCTION OF GAEnsure 2 skilled assistants presentWedge below the right hip to allow uterine
displacementPreoxygenate with 10 l/minute for 3 minutesAdminister Thiopentone 4-5mg/kg, Suxamethonium
100 mgCricoid pressure is applied Ensure correct ETT positionMedium acting muscle relaxant after Suxamethonium
has worn offNO OPIOID till baby is delivered.
GENERAL ANAESTHESIAMAINTENANCE OF GAO2:N2O ratio 1:1 with volatile MAC<1Aggressive treatment of hypotensionAfter baby delivered, change O2 : N2O to 1:2 ratio IV Oxytocin 5U slowly followed by infusion 40-80U over 4
hours IV opioid: Morphine 5mgAssess blood lossRectal Diclofenac 100mg and SC LA infiltration Reversal and awake extubationMove the patient to the recovery area
PROBLEMS WITH GA IN MATERNITY PATIENTS
1. Awareness• Incidence 0.7 – 1.5%• Due to :
i) no sedative premedications, ii) high FiO2 iii) low volatile concentration used intraoperatively iv) avoidance of opioids
PROBLEMS WITH GA IN MATERNITY PATIENTS
2. Pulmonary aspiration• pH<2.5 with volume >25mls ~critical factor• Signs: - intraop bronchospasm
- desaturation- postop tachypnoea and cyanosis
• Mx: - Immediate head down with oral/ETT suction, may need bronchial lavage.
- Treat bronchospasm with bronchodilator.
- Increase FiO2 and PEEP.
PROBLEMS WITH GA IN MATERNITY PATIENTS
3. Difficult intubation• FaiIed intubation incidence 1:280 compared
with 1:2200 in non-pregnant. • Aim: - maintain oxygenation,
- avoid aspiration
HEAD ELEVATED LARYNGOSCOPY POSITION “stacking”
MATERNAL DISEASES IN PREGNANCY1. Hypertensive disorders 11-17%
2. Gestational diabetes 5-11%
3. Valvular heart disease (less common)
HYPERTENSIVE DISORDERS OF PREGNANCY
Definition: BP > 140/90mmHg after 20 weeks of gestation
and settles within 6 weeks of delivery
Types:Gestational (without proteinuria)Preeclampsia (proteinuria >0.3g/day)
Severe preeclampsiaEclampsia
SEVERE PREECLAMPSIA
Def: BP >160/110 mmHg with proteinuria >5g/d associated with signs of organ hypoperfusion:
Oliguria < 500ml/dayCerebral disturbancesEpigastric /RUQ painPulmonary oedemaHELLP syndromes
Management:Anti hypertensiveLabour analgesiaEarly delivery
ECLAMPSIA
Def: Generalized convulsion during hypertensive pregnancy up to day 7 of post delivery.
Management:ABCAbort seizureIV MgSO4 Anti hypertensiveEarly delivery
CARDIOVASCULAR DISEASES IN PREGNANCY
Clinical features:SOB at rest, ↓ET,
orthopnoeaPedal oedemaTachycardia, systolic
murmurs, S3, basal rales
Recognition is important
Management:Multidisciplinary
consultationReferral to tertiary
centreEarly planning of
mode of delivery
ANY QUESTION ?