NITRIC OXIDE

&

POST PARTUM

HGE

Magdy abdelrahman mohammed

2014

“The Molecule of Life”

Nitrates, Nitrites

and Nitric Oxide

Nitrate = NO3

Nitrite = NO2

Nitric oxide = NO

Nitric oxide

Nitric oxide mediate a wide range of

physiologic processes that include

the inhibition of platelet aggregation,

smooth muscle relaxation,

neurotransmission, host defense, and

inflammation.

Nitric oxide and Nobel prize

In the early 1980 at the New Work , Dr Robert

was presented conflicting result by his two

technicians. one technician always found the

acetylcholine relaxed the blood vessel while

the other, found it always cause contraction.

He noticed that one technician handled the

vessels roughly, and rubbed off the thin layer

of endothelium from the surface of the vessel,

while the other was careful and kept the

endothelium intact.

Then he realized that an intact

endothelium is a prerequisite for the

relexant effect of acetylcholine this

substance named endothelium-dependent

relaxing factor (EDRF) which then

discovered that EDRF was identical to

nitric oxide.

The structure and nature of Nitric Oxide

Nitric oxide is a di atomic free radical consisting of

one atom of nitrogen and one atom of oxygen.

Lipid soluble and very small for easy passage

between cell membranes.

Short lived, usually degraded or reacted within a few

seconds.

The natural form is a gas.

N O

Nitric oxide is produced by nitric oxide

synthase (NOS), which catalyzes the

conversion of L-arginine to L-citrulline and

has three isoforms:

Endothelial.

Neuronal.

Inducible.

NO is a free radical (a free radical

contains an unpaired electron in its

outer orbital) (Andreoli, 1995).

On the other hand, NO may react

with oxygen radicals forming less

toxic molecules acting as an

antioxidant (Kanner et al., 1991).

The nitric oxide system in

normal pregnancy

In animal studies, it was found that NO

system is up-regulated during pregnancy

and inhibits uterine contractility until term.

It may contribute to the maintenance of

uterine quiescence during pregnancy and

its withdrawal prior to term may trigger

parturition.(Conrad et al., 1993; Izumi et al., 1993; Yallampalli et al., 1994; Sladek and

Roberts, 1996)

There is also evidence that the

physiological vascular adaptation to

pregnancy (increased blood volume,

increased cardiac output and decreased

vascular resistance) is accompanied by an

increase in endogenous NO production.

(Izumi et al., 1994; Nelson et al., 1995).

POSTPARTUM

HEMORRHAGE

Definition

>500 ml.

>1000 ml.

Hemodynamic instability.

Blood loss is often underestimated.

Etiology of Postpartum

Haemorrhage

Tone Uterine atony 90%

Tissue Retained tissue/clots

Trauma laceration, rupture.

Thrombin coagulopathy

What is relation between

postpartum hge & nitric

oxide ?

Can we

Predict

PPH?

Who is

at

risk?

Why nitric oxide?

Anemia.

Stress. Nitric

oxide

Hypoxia.

Uterine atony

Criticism

200 cases involved during one

month.

12 entered in atonic Postpartum hge.

2 of them uncontrolled &

hysterectomy was done as life saving

?

Taken in consideration exclusion

criteria.

No cut off level of nitrite

Nitric oxide & retained

placenta

I. V nitroglycerine.

Retained placenta in 33 cases were

extracted within 4 minutes of the 1st bolus

(150 ug).

Only one patient required ergometrine for

continued atony.

Non of them need trasfusion.

Lowenwirt IP et al, 1997.