Pregnancy is characterized by many biohumoral changes: circulation, respiratory mechanics, oncotic pressure, vascular permeability and many other systems are affected.

Vascular permeability is controlled by endothelial glycocalyx. Several factors such as sepsis, ischemia / reperfusion, inflammatory mediators, trauma, surgery including the Cesarean Section and fluid overload can increase vascular permeability due to a glycocalyx damage.

During Cesarean Section under subarachnoid anesthesia, hypotension may occur. It is a common side effect caused by reduced preload due to aortocaval compression by the uterus. Furthermore, subarachnoid anesthesia causes block of the sympathetic preganglionic fibers which is associated with vasodilation. These changes often require the use of vasopressors and fluids.

A fluid overload associated with the physiological and pathological factors discussed earlier might cause an increased risk of pulmonary edema and acute respiratory failure (IRA) in women undergoing cesarean section under arachnoid anesthesia.

IRA occurs in less than 0.2% of total pregnancies but it is one of the most common cause of admission to intensive care unit in pregnant women.

Among the causes that can lead to IRA in the last trimester of pregnancy we find pneumopathies such as asthma, pulmonary embolism due to amniotic fluid and pulmonary edema related to severe preeclampsia.

Diagnosis of pulmonary edema can be clinical or sub-clinical through laboratory tests such as BNP (b-type natriuretic peptide). It might also be necessary to execute instrumental examinations such as chest radiography (contraindicated in pregnancy) or trans-thoracic ultrasound.

Hypothesis: correlation between subarachnoid anesthesia, fluidic therapy and BNP values and ultrasound pattern

Inclusion Criteria:

woman submit elective Cesarean Section:

• age > 18 years
• American Society of Anesthesiologists (ASA) physical status classification system > 2
• > 37 gestational age
• arterial pressure >/ = 140/90 mmHg and proteinuria < 300 mmHg during anesthesia pre-examination
• no known cardiovascular/respiratory disease
• pre-partum pulmonary echography

Exclusion Criteria:

• age < 18 years
• pulmonary echographic windows not satisfying
• blood loss during Cesarean Section more than 1000 mL and/or necessity to administer colloid
• postpartum hemorrhage within the first 24 hours following childbirth
• pre-eclamptic sign/symptoms within the first 5 days following childbirth
• twin pregnancy

Patients' anthropometric data were collected, data related to the anesthetic technique, pharmacological and intraoperative fluid therapy, sensory level reached after subarachnoid anesthesia, sensory level and motor blockade at discharge from the operating room. We also collected BNP serum values and pulmonary ultrasound images at 6 and 24 h after the intervention. Diuresis collection at 6 and 24 h after the intervention was registered as well as water balance.