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Obstetrics physiological changes
- 1. JIMMA UNIVERSITY Anesthesia Department By. Mohammednur Husen (BSc, MSc in Anesthesia And MBA student)
- 3. Objectives •At the end of this class the students will be able to •Describe maternal anatomic and physiological changes during pregnancy •Manage supine hypotension syndrome •Use right Anaesthetic management to obstetrics physiologic changes.
- 4. Anaesthesia for parturient What is the difference? 4 2 Lives are cared For simultaneously Alter the usual response to anaesthesia Physiological changes Fetus Mother PHysiologic changes of obstetrics mother
- 5. Maternal Physiology during Pregnancy 5 CNS 1) Progressive MAC. by 40% at term Returns to normal by 3rd day postpartum. Progesterone increases 20 times normal level at term β- endorphin surge during labor & delivery PHysiologic changes of obstetrics mother
- 6. Cont… 6 2) ↑ Sensitivity to Local Anesthetics. • LArequirements during RA ↓ by 30%. Hormonally Mediated Engorged Epidural Venous Plexus ↓CSF Volume ↑Epidural space Pressure ↓Volume of Epidural Space PHysiologic changes of obstetrics mother
- 7. During pregnancy RS physiology 7 ٌRespiratory system • ↑Oxygen consumption 20 – 40% Progesterone↑ CO2 Production ↑Minute Ventilation 40 – 50% ↑↑ VT & ↑ RR ↑PaO2 (30 mmHg) and ↓ PaCo2 (28-32mmHg) Compensatory ↓ HCo3ˉ PHysiologic changes of obstetrics mother
- 8. Lung volumes & capacities at term gestation in absolute volumes & as the percentage change from non-pregnant Values. 8 TLC 4550ml -5% VC 3500ml No Change IC 2650ml +15% 2000ml +5% IRV 650ml +45% VT FRC 1900ml -20% 850ml -25% ERV 1050ml -15% RV PHysiologic changes of obstetrics mother
- 9. 9 ↓ FRC + ↑O2 Consumption = Rapid desaturation during periods of apnea. ☼Pre-oxygenation prior to GA is mandatory. ☼Parturient Should not lie flat without supplemental oxygen. ↓FRC & ↑MV ☼ ↑Uptake of Inhalational Anesthetics. PHysiologic changes of obstetrics mother
- 10. 10 Hormonal Changes Capillary engorgement of respiratory tract mucosa 1)↑Incidence of difficult intubation. 2) Trauma and bleeding during endotracheal intubation. ☼ Use a small ETT (6 – 7 mm) during GA PHysiologic changes of obstetrics mother
- 11. 11 Hematological Changes I : ↑ Blood Volume ( up to 90ml/ Kg) ↑ by 1000 – 1500 ml at term. Returns to normal 1 – 2 weeks postpartum. ↑ Plasma Volume > ↑ RBC mass + = Dilutional anemia & ↓ blood viscosity Facilitates maternal & fetal exchange of respiratory gases, nutrients & metabolites ↓ Impact of maternal blood loss at delivery PHysiologic changes of obstetrics mother
- 12. 12 II : Hypercoagulable state ↑ Fibrinogen,factors VII, VIII, IX, X & XII ↓Factor XI Risk Of DVT One of the leading causes of maternal mortality PHysiologic changes of obstetrics mother
- 13. III : Other changes: 13 * Leucocytosis up to 21,ooo/µL. * 10-20% ↓ in platelet count. * Marked ↓ cell mediated immunity→ ↑susceptibility to viral infection. PHysiologic changes of obstetrics mother
- 14. 14 CVS ↑ COP by 40% at term ↑ HR 15 – 30% ↑ SV 30% Returns to normal 2 weeks postpartum. ↓ SVR → ↓ SBP & ↓↓ DBP, the response to adrenergic and vasoconstrictor agents is decreased. CVP, PAP, PAWP → unchanged. PHysiologic changes of obstetrics mother
- 15. 15 Supine Hypotension syndrome COP ↓ in supine position after 28th week of gestation. Occurs in 20% of women at term. Compression of IVC Compression of lower aorta Aortocaval compression ↓ blood flow to kidneys, utero-plancental circulation &lower extremities ↓ VR → ↓ COP by 24% at term. PHysiologic changes of obstetrics mother
- 16. Cont… Supine Hypotensive Syndrome/ vena caval syndrome 16PHysiologic changes of obstetrics mother
- 17. http://www.manbit.com/OA/f28-1.htm 17PHysiologic changes of obstetrics mother
- 18. Manbit imageshttp://www.manbit.com/OA/f28-1.htm 18PHysiologic changes of obstetrics mother
- 19. 19 Compensatory mechanisms in Unanaesthetised Women Venous Collaterals Paravertebral Venous plexus Abdominal wall ↑ SVR & HR PHysiologic changes of obstetrics mother
- 20. 20 No woman in late pregnancy should lie supine without shifting the uterus off the great abdomino-pelvic vessels. Left lateral decubitus Tilting the table Left side down Rigid wedge under The right hip Fluid preloading before neuroaxial anesthesia It does not completely avoid maternal hypotension but it↑ maternal COP → preserve uteroplacental blood flow. PHysiologic changes of obstetrics mother
- 21. Cont… • In addition to lateral positioning, supine hypotension syndrome treatment may include • Monitor • Fetal heart tones • Maternal vital signs. • Initiate an IV of normal saline. PHysiologic changes of obstetrics mother 21
- 22. 22 GIT ☼ Upward displacement of the stomach by the uterus → Incompetence of gastroesophageal sphincter → Gastroesophageal reflux & esophagitis. The parturient should be considered a full stomach patient during most of gestation ☼ ↑ Progesterone → ↓ tone of the sphincter. ☼ Placental Gastrin → Hypersecretion of gastric acid. ☼ Gastric emptying → Delayed with labor. PHysiologic changes of obstetrics mother
- 23. 23 Pharmacological prophylaxis against aspiration. No positive pressure ventilation before intubation Rapid sequence induction with Sellick’s maneouvre For GA: PHysiologic changes of obstetrics mother
- 24. 24 Renal System ♦ RBF & GFR ↑ by 50% at 1st trimester but returns to normal in 3rd trimester. ♦↑ Renin & Aldosterone → Na+ retention. ♦ Sr. Creatinine & BUN may ↓ to 0.5 –0.6mg/dL &8 – 9 mg/dL respectively. ♦↓ Renal tubular threshold for glucose & amino acids → mild glycosuria (1-10g/d) & proteinuria (<300mg/d). ♦ Plasma osmolality ↓ by 8 – 10 mosm/Kg. PHysiologic changes of obstetrics mother
- 25. 25 Hepatic Effects ♦Hepatic function & hepatic blood flow→ unchanged. ♦Minor ↑ in Sr. Transaminases & LDH in 3rd trimester. ♦↑ Sr. Alkaline phosphatase (placental). ♦ Mild ↓ in Sr. albumin (dilutional). ♦ 25 – 30% ↓ in pseudocholine estrase activity. ♦↑ Progesterone levels→ inhibit release of cholecystokinin→ incomplete emptying of gall bladder→ altered bile acid composition→ formation of cholesterol stones. PHysiologic changes of obstetrics mother
- 26. 26 Metabolic Effects Pregnancy is Diabetogenic Human Placental lactogen→ relative insulin resistance. Starvation like state ↓ Blood Glucose & Amino Acid levels. ↑ Free Fatty Acids, Ketones & triglycerides. ↑ Estrogen levels→Thyroid gland hypertrophy→ ↑ T3 & T4 ↑ TBG → Free T3, T4 & TSH remain normal PHysiologic changes of obstetrics mother
- 27. • Conjuctival vasospasm and subconjuctival hemorrhage. • Retinal detachment • Retinopathy associated with hypertensive disorders. • IOP-decrease b/se of progesterone and relaxine effects which facilitate aqueous humor out flow and human chorionic gonadotropin which depress aqueous humor production 27PHysiologic changes of obstetrics mother Ocular changes
- 28. References Different website Morgan and Mikhail's clinical anesthesiology 5th edition PHysiologic changes of obstetrics mother 28
- 29. PHysiologic changes of obstetrics mother 29 Thank you !