Subarachnoid Hemorrhage And Pregnancy (PART 4) ~ Medical Review

Physiologic changes of pregnancy: Anesthetic management (1)

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1.Increase in cardiac output(C0) Careful monitoring of intravascular

volume.

2.Increase in uterine size. Aortocaval compression in supine

position;maintain left lateral uterine

displacement perioperatively.

3.Reduced FRC ,increased 02 Preoxygenation higher Fi02.

consumption.

4.Increase in minute ventilation Monitor changes in PaC02 closely.

decrease in PaC02,leftshift of prevent hyperventilation,avoid dec-

oxyhemoglobin dissociation rease in C0,UBF,02 supply to the

curve. fetus.

5.Decrease in gastric emptying Aspiration prophylactis ,rapid sequ-

gastro oesophageal reflux. ence induction.

6.Maternal hyperventilation ,re- Monitor EtC02,mantain adequate

duced PaC02,cerebralvaso- CPP.

spasm,cerebral ischemia/in-

farction.

7.Reduced MAC for inhalation Avoid overdose and cardiovascular

anesthetics. depression.

8.Decreased epidural and sub- Decrease local anesthetics require-

arachnoid space. ment for regional anesthesia.

9.UBF is not autoregulated and Avoid hypotension and consequent

is proportional to mean perfu- decrease in UBF with reduced 02

sion pressure. to the fetus.

10.Decrease in serum choline es- Monitor neuromuscular blockade

terase. after succinylcholine use.

Adverse uteroplacental drugs effects (2)

Drugs adverse effects

Phenytoin minimal

Thiopental neonatal depression(>8mg/kg in

humans),worsening of preexisting

fetal distress caused by maternal

hemodynamic effects.

Lidocaine Uterine hypertonus and vasocons-

triction with fetal distress (toxic

dose in sheep);worsening of pre-

existing fetal distress.

Mannitol Oligohydromnios with fetal hyper-

osmolarity,hypernatremia,dehyd-

ration,cyanosis,bradycardia(12,5

g/kg in rabbits);fetal hyperosmo-

larity in humans 1 hr after 200g

intravenous.

Furesemide Possible dilatation of ductus arte-

riosus,electrolyte abnormalities.

Nitropruside Decreased uterine vascular resis-

tance;electrolyte abnormalities,

lethal fetal cyanide levels with on-

set of maternal tachyphylaxism

sheep.

Nitroglycerine Decreased uterine vascular resis-

tance.

Hydralazine Decreased uterine vascular resis-

tance.

Propranolol Decreased umbilical blood flow in

sheep,premature labor,worsen-

ing of preexisting fetal distress

neonatal acidosis,bradycardia,

hypoglycaemia,apnea,diminished

response to hypoxia and acidosis

Management of subarachnoid hemorrhage(SAH) in pregnancy:(1)

Lesion Pregnancy Management

1.Incidental aneurysm before 26 weeks Risk of SAH regardless

of the mode of delivery

surgical treatment of a

neurysm reduces risk

for both mother and

baby.

2.Incidental aneurysm 34 - 36 weeks C-Section,aneurysm

clipping under same a-

nesthetic.The take ho-

me rate is same as full

term infants.

3.Corrected aneurysm Any stage Negligible risk of bleed

ing needs normal obs-

tetric management.

4.Ruptured aneurysm Before 26 weeks Aneurysm surgery and

vaginal delivery at term

according to obstetric

indication.

5.Ruptured aneurysm Beyond 26 weeks Moribund patient-->

C-section to save the

infant.

6.Ruptured aneurysm Beyond 34 weeks Neuroresuscitation to

unstable patient CT/angiogram --->

C-section and aneu-

rysm surgery;maintain

uterine tone during

lengthy surgery.

7.Ruptured aneurysm In utero death Aneurysm surgery and

then vaginal delivery.

8.Unruptured AVM Term pregnancy No C-section when no

adverse circumtance

prevail.

9.Ruptured AVM Before 26 weeks Conservative manage-

ment (risk of rebleed

less than aneurysm).

10.Ruptured AVM un- Term pregnancy Neuroresuscitation ->

stable. CT/angiogram-->C-

section --> surgery

and excision of AVM.

PERIOPERATIVE MANAGEMENT:(1,2)

Management of SAH during pregnancy is similar to that in non pregnant patients and depends on the neurologic condition of the mother and the stage of pregnancy.
Craniotomy for aneurysm is perfomed under neurosurgical criteria while C-section is done for obstetrics indication.

Perioperative management depends on the neurologic evaluation,viability of the fetus,effect of anesthetic technique and drugs on intracranial pressure,uteroplacen
tal transfer of the drugs and their teratogenicity and effect on uterine relaxation.

Before fetal viability (<32 weeks) and patients with good SAH grades surgical clipping should be performed as soon as possible to prevent rebleeding. About 80% of these patients aneurysm ruptures occur before 36 weeks of pregnancy.
In these patients aneurysm clipping followed by delivery
at fullterm generally in a satisfactory outcome for both
the mother and infant.

During craniotomy continuous fetal heart rate monitoring should be used with an obstetric team available.

If fetal distress develop,caesarean delivery may be considered.

In general the timing and method of operative corrections should be decided on neurosurgical grounds without regard to the status of pregnancy.

A C-section is indicated when the mother moribund after SAH to preserve a fetus deemed mature enough for delivery.

Oxytocix drugs have been used to decrease uterine atony and bleeding after delivery without causing detererious neurologic effects although they have not been studied extensively in this setting.
The most common hemodynamic alteration with oxytocin is hypotension whereas hypertension is associated with methyergonovine maleate (methergine) and proataglandins.
The basic requisite of intraoperative management are the maintenance of adequate cerebral perfusion and favourable operative field ,monitoring fetal homeostasis and uterine relaxation,preventing fetal depression.

Patients who have AVMs are morelikely to suffer intracra
nial hemorrhage during labor than are those who have aneurysm. In an AVM is amenable to surgical treatment there is no need to delay this treatment because of pregnancy although a case of successful management of pregnancy to term followed by delivery without incident has been reported.

The basic management consist of:(1)

1. Smooth induction:

Avoiding rebleeding from rise in blood pressure and cereb
ral ischemia from hypotension and hypovolemia.

2.Controlled laryngoscopy:

Avoid both rise in BP and rise in ICP.

3. Prevent aspiration of gastric content:

As with any other C-section it is imperative to prevent
regurgitation and aspiration of gastric contents.
Metoclopropamide,ranithidin,anticholinernics,and
famotidine have been used preoperatively to reduce both
gastric volume and acidity in pregnant women.
Oral sodium citrate given immediately before induction
has also been shown to increase the pH of gastric
contents.

A rapid sequence induction with thiopental,succinylcho
line or rocuronium intravenous lidocaine,fentanyl and
propranolol or sodium nitropruside (SNP) and cricoid
pressure have been used in good results.

4.Avoid fetal depression :

Discontinue long acting drugs such as diazepam,and pheno
barbital and use drugs that do not depress the infant.

5.Prevent uterine relaxation:

Avoidance of inhalational drugs like halothane is impor
tant to prevent uterine relaxation with consequent
hemorrhage in the postpartum period.Isoflurane to 1% has
been used in such situations with good outcome,as it has
been shown to reduce awareness and blood loss during C-
section.

6.Control of blood pressure(BP):

Systemic hypertension increases the CBF,CBV,and ICP
and may induce rebleeding.
Controlled hypotension or temporary proximal occlusion
meets surgical requirements.
The use of SNP in obstetrics is still controversial owing to
the potential toxicity from cyanide and fetal hypoxia
from the hypotension induced reduction in placental
perfusion. With judicious use of SNP however,fetal
compromise may be kept atbay.

7.Control ICP :

Mannitol an osmotic diuretic,may have adverse effects on
the fetus including dehydration and bradycardia.

8.Management of ruptured aneurysm intraoperatively:

Aggressive restoration of acute blood loss, hypotension
(anesthesia, SNP or ipsilateral carotid compression)
avoidance of excessive ventilation and a relaxed brain.

9.Maintain uetrine tone:

Oxytocin has been safely infused after combined neuro
resuscitation and C-section and continued throughout
the subsequent angiogram and six hours craniotomy for
clipping of saccular aneurysm of the middle cerebral
artery with hyppocampal herniation and evecuation of
a large hematoma in the left tempoparietal region.
The hypertension caused by methyl ergonovine maleate
and prostaglandin for treatment of uterine atony maybe

detrimental the aneurysm is secured.

10.Ventilation during anesthesia has to be carefully
matched to the needs of patients with due consideration
for the unborn baby.Hyperventilation may aggrevate
preexisting cerebralvasospasm and will also cause
uteroplacental insufficiency due to vasoconstriction with
attendant felal hypoxia and acidosis.

11.Continous BP monitoring :

This is essential when hypotensive drugs are employed.
Monitoring arterial blood gases(ABG) in the perioperative
period will confirm adequate oxygenation,effective CO2
elemination,and metabolic homeostasis may indicate
the early occurence of cyanid toxicity.

12.Urinary output:

Good urine output is an indication of adequacy of intra
vascular volume and organ perfusion and the effective
ness of diuresis.

13.Fluids,electrolytes,glucose and osmolarity must be moni
tored closely to detect and treat contracted intravascu
lar volume and disordered sodium and potassium
balance.

Summary :

Because these aneurysms present primarily in the third trimester of pregnancy,the anesthesiologist must face the possible complications associated with pregnancy and the special consideration for aneurysm clipping.The anesthetic management also depends on the gestational age,and obstetric plan,that is whether delivery of the fetus will precede the neurosurgical procedure or whether the aneurysmal clipping will be done followed by normal maturations of the fetus with subsequent delivery at term.

The goal of anesthesia during pregnancy are to ensure the recovery of the mother and the normal continuation of pregnancy without damage to the fetus. The anesthetic management should be the same as for the non pregnant aneurysm patient except that one is taking care of two patients. Pregnant patients have special needs because of the physiologic changes that occur during pregnancy including consideration for decrease in MAC, an increased potential for aspiration and having difficult airway,special positioning,the influence of anesthetic induced depression on maternal BP and the risk of inducing premature labor.

Special needs with respect to the fetus are,adequate fetal maternal oxygen exchange which depends on adequate maternal BP,potential for teratogenic effects secondary to drugs and perioperative monitoring of the fetus.

One should anesthetize the patient to an adequate depth of anesthesia with the aim of preventing aneurysmal rupture during induction as well as during maintenance and accept the price of neonatal depression.

Equipment and personal for for neonatal resuscitation should be at hand when delivery occurs.

REFERENCES :

1.Newfield Philippa,Hamid AK,Rukayya,Lans M.Arthur:
Subaracnoid hemorrhage and Pregnancy:Albin S Maurice:
Textbook of Neuroanesthesia with Neurosurgical and
Neuroscience perspectives;The MCGraw Hill Companies
Newyork,St.Louis,San Franscisco 1997.pp 885-91.

2 Lam M Arthur:Cerebral aneutysm:Anesthetic considera
tion:Subarachnoid and Pregnancy;Cottrell E James.Smith
S David;Anesathesia and Neurosurgery,4th edit,Mosby
Inc,St Louis,London,Philadelphia,Sydney,Toronto,2001.
pp 385-88.

3.Stone J.D,Bogdonoff L David: Anesthesia for intracranial
surgery;Stone J.D,Sperry J Richard;The Neuroanesthesia
Handbook, Mosby Company,st.louis,Baltimore,Boston ,
1996.pp 352-3.

4.Morgan Barbara:The physiology of Pregnancy and
Anesthesia:Morgan Barbara; Foundations of obstetric
Anesthesia,Farrand Press,London,1987.pp 126-33

5.Barrier G,Surean C:Effects of Anesthesia and Analgesic
drugs or Labor Fetus and Neonate;Rosen Michael;Clinics
in Obstetric and Gynaecology,WB Saunders Company
Ltd,London,Toronto,Philadelphia,1982,pp.351-61.

6.Snow C Johnson: Anesthesia and Analgesia in Obstetric
and Gynaecology;Manual of Anesthesia,Asian edition,
Little Brown and Company Boston,Tokyo ,1978,pp.427-29.