1. Anestesia Regional en Obstetricia: qué repercusión

existe en la dualidad Materno/Fetal?

2. Cómo afecta la hipotensión en la Anestesia Espinal?

3. Analizar brevemente la circulación fetal.

2. Revisar la fisiología de la Oxigenación fetal.

3. Qué implicaciones prácticas se pueden concluir?.

Haggard HW: 1929

Devils, Drugs, and Doctors: The Theory of the

Science of Healing from Medicine Man to Doctor

Porque oí un grito como de mujer de parto, angustia como de

primeriza; era el grito de la hija de Sion que se ahogaba, y

extendía sus manos, diciendo: ¡Ay ahora de mí, porque

desfallezco ante los asesinos!

Jeremías 4:31

1. Parto o Cesárea?

2. Cuánto tiempo se dispone?

3. Cuál es el pronóstico del niño?

4. Condición anatómo/fisiológica de la madre?

5. Opciones Anestésicas:

• Anestesia General

• Anestesia Regional:

1. Espinal

2. Peridural

3. Mixta

Factores que afectan la

transferencia placentaria de

medicamentos (Materno/Fetal)

Drogas que cruzan la Placenta

The neonate may also be adversely affected by maternal

hypotension and reduced uteroplacental perfusion. In most

instances, however, maternal hypotension of short duration is

associated with transient fetal carbon dioxide retention and is

of limited clinical consequence.

Neuraxial Anesthesia for Cesarean Delivery:

What Criteria Define the “Optimal” Technique? Dan Benhamou, MD, Anesth & Analg,

Vol. 109, No. 5, Nov. 2009

1. Riley ET, Cohen SE, Macario A, Desai JB, Ratner EF. Spinal versus epidural

anesthesia for cesarean section: a comparison of time efficiency, costs,

charges, and complications. Anesth Analg 1995;80:709–12

2. Riley ET. Spinal anaesthesia for Caesarean delivery: keep the pressure

up and don’t spare the vasoconstrictors. Br J Anaesth,2004;92:459–61.

A 1995 landmark study by Riley established the advantages of spi-

nal compared with epidural anesthesia for cesarean delivery.

Maternal haemodynamic changes during spinal

anaesthesia for caesarean section Eldrid Langesæter, Current Op in Anesth, 2011, 24:242–248

Key points

1. The typical haemodynamic effects of spinal anaesthesia in

healthy pregnant women are a decrease in systemic vascular

resistance and a compensatory increase in cardiac output;

phenylephrine is, thus, the first-line vasopressor.

2. The rarer presentation of hypotension and bradycardia should

be treated with ephedrine and/or anticholinergics.

Spinal is commonly for caesarean. Advantages for the mother: remaining

awake for the birth, no risks of General and facilitating POP pain relief. The

commonest side-effect of spinal is hypotension, which is often

accompanied by nausea or vomiting, or both. Severe hypotension poses

serious risks to mother (loss of consciousness) and baby (lack of O2 and

brain damage).

The review found that no single method completely prevents hypotension,

but the incidence is reduced by administering IV fluids, ephedrine or

phenylephrine, and by compressing the legs with bandages, stockings or

inflatable boots.

S U M M A R Y

Conclusion:

There is not one accepted definition of hypotension in the scientific

literature. The incidence of hypotension varies depending on the chosen

definition. Even minor changes of the definition cause major differences in

the frequency of hypotension.

1. Incidencia de hipotensión: 50% a 80%.

2. La simpatectomía causa vasodilatación y consecuente disminución

de RVS.

3. La presión baja disminuye el flujo sanguíneo en la art. uterina, lo

que indi-rectamente afecta al feto. Si persiste puede ocurrir acidosis

fetal. (10 min de Flujo - 65% = Acidosis).

Clin Chest Med

32 (2011) 15–19

Intrapartum Fetal Pulse Oximetry: Clinical Application

Vol 55(3), March 2000, pp 173-183

The normal range of fetal arterial oxygen saturation (FSpO2), 30 to 70%, lies in the middle of the O2 dissociation curve, so that small changes in pH or PO2 cause large changes in FSpO2

Curva de saturación de la oxihe-

moglobina para el feto (A) y adulto (B)

Patrón circulatorio en el útero

The fetus has made four major adaptations to compensate for the low PO2.

1. The rate of perfusion of fetal organs in sheep preparations is 2.5-fold

greater than blood flow to the same organs in the adult.

2. Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin.

3. Third, fetal hemoglobin levels are increased over adult values.

4. A system of vascular shunts and streaming effects directs oxygenated

blood to high-priority tissue in the liver, heart, and brain and guides

deoxygenated blood back to the placenta.

DETERMINANTS OF FETAL

OXYGENATION

Adkinson: Middleton's Allergy:

Principles and Practice, 7th ed.

Clin Perinatol, 36 (2009) 655–672

Sir Joseph Barcroft first drew a close analogy between the low partial pressure

of oxygen of the fetus in utero and that which would be found in humans at an

altitude of 30,000 to 33,000 ft on Mt. Everest when he observed, ‘‘The fetus then

grows in an environment the oxygen concentration of which is falling all the

time—an uphill business you may say. True indeed, for is it not the problem of

Everest, the maintenance of the organism in the atmosphere becoming

progressively rarer?’’ He later neatly summarized this concept with the phrase,

‘‘Mt. Everest in utero.’’

1. Barcroft J. The conditions of foetal respiration. Lancet

1933;222(5749):1021–4.

2. Barcroft J. Researches in prenatal life. London: 1946.

In conclusion, we found that labor CSE in patients with cervical

dilation >3 cm, ruptured membranes, and fetal descent, does not

significantly alter fetal oxygenation. The impact of labor CSE on

FSpO2 is minimal and appears similar to epidural analgesia.

EXTRÍNSICAS

• Tabaquismo

• Alcoholismo

• Drogadicción

• Infecciones virales

FETAL

• Trisomías cromosómicas

• Desórdenes Mendelianos

• Alt. Anatómicas congénitas

• Otros Síndromes

FAC. PLACENTARIOS

• Mosaicismo

• Implantación anormal

• Útero anormal

• Abruptio plac. crónico

MATERNAS

• Hipertensión

• Pre-eclampsia

• Sx. antifosfolipidos

• Trombofilia

DESÓRDENES EN EL

DESARROLLO

FETAL

Pathophysiology of Fetal

Growth Restriction:

Implications for Diagnosis

and Surveillance

Ahmet Alexander Baschat, MD

Vol 59, Number 8

OBSTETRICAL AND

GYNECOLOGICAL SURVEY

CAUSAS Y

CONDICIONES

Abstract:

The neonate must make a transition from the assured continuous

transplacental supply of glucose to a variable fat-based fuel

economy. The normal infant born at term accomplishes this

transition through a series of well-coordinated metabolic and

hormonal adaptive changes.

Metabolic adaptation at birth Ward Platt M AUG-2005; 10(4): 341-50

Seminars in Fetal & Neonatal Medicine Newcastle Neonatal Services, Royal Victoria Infirmary, Department of Child Health, Queen

Victoria Road, Newcastle upon Tyne NE1 4 LP, UK.

The Internet Journal of Gyn anMd Obst, 2008 : Vol 9 Number 2

Intrapartum Fetal Resuscitation: A Review Dushyant Maharaj MBBS

1. DISMINUCIÓN EN LA FRECUENCIA CARDÍACA.

2. REDUCCIÓN EN EL CONSUMO DE O2, SECUNDARIO

A CESE DE FUNCIONES NO ESCENCIALES.

3. REDISTRIBUCIÓN DEL GC A ÓRGANOS VITALES.

4. INCREMENTAR EL METABOLISMO CELULAR ANAEROBIO.

Bearing in mind that the intrauterine PO2 amounts to only 25–30mmHg in contrast

to the adult 90–100 mmHg, this would enable the fetus to maintain a similar

metabolic rate to the mother despite a much lower PO2 and, thus, would exactly

correspond to the metabolic adaptation of fetal mammals

Metabolic adaptation to hypoxia:

cost and benefit of being small Dominique Singer

Respiratory Physiology & Neurobiology

141 (2004) 215–228

Foca de Weddell

Nutrientes y

Oxígeno

Respuesta al

estrés

Alteración en

Intercambio gas

Perfusión a

Órganos vitales

Hipercapnea

Fetal

Disminución del

Crecimiento

Acidosis

Respiratoria

Hipoxemia

Fetal

Acidosis

Láctica

Metabolismo

Anaeróbico

Sufrimiento de

Órganos

Bradicardia e

Hipotensión

Muerte Fetal

Intraútero

Perinatal asphyxia pathophysiology in pig and human:

A review Animal Reproduction Science xxx (2005) xxx–xxx

María Alonso-Spilsbury, Daniel Mota-Rojas

Intrapartum Assessment of the Fetus: Historical

and Evidence-Based Practice

Gary A. Dildy III, M

Obstet Gynecol Clin N

Am 32 (2005) 255– 271

The Timing of Birth A hormone unexpectedly found in the human placenta turns out to

influence the timing of delivery. This and related findings could

yield much needed ways to prevent premature labor

Scientific American March 1999

Endocrinology of Parturition

Victoria Snegovskikh, MD

Endocrinol Metab Clin N Am

35 (2006) 173–191

Endocrinology of Parturition Victoria Snegovskikh, MD

Endocrinol Metab Clin N Am

35 (2006) 173–191

C A Resistencia miometral:

• tono • contracciones

Tono Vascular

Viscocidad sanguínea

Hb SO2

CVCI Hb

Contenido de O2

Resistencia Intrínsica

Pr. Art . Uterina Pr. Vena . Uterina

Hipotensión Sistémica

Presión Perfusión Uterina

Resistencia Vascular Uterina

Pr y Flujo Sanguíneo Uterino

Aporte Uterino: Nutientes y O2

RESUCITACION CARDIOPULMONAR

EN LA EMBARAZADA

Dr. MAURICIO VASCO RAMÍREZ

MONITOREO:

• Tococardiografía, pH Fetal

• Lactato Fetal, Pulso Oximetría Fetal

OPTIMIZAR O2 MATERNO

• Administración de O2 a Pr. mormal

• O2 a Presión Positiva

OPTIMIZAR PERF. PLACENTARIA

• Adecuar / discontinuar Occitocina,

• Tocolíticos: disminuir hiperestimu-lación

• Efedrina: cruza la placenta y al aumentar el metabolismo fetal puede producir acidosis fetal y taquicardia materno/fetal

• Fenilefrina: no altera la perfusión, ni genera acidosis, pero bradicardiza al feto y la madre.

COMBINACIÓN EFECTIVA: FENILEFRINA + EFEDRINA + CO-HIDRATACIÓN + MANIOBRAS FÍSICAS

OPTIMIZAR PERFUSIÓN UTERINA:

• Lateralización materna

• Vasopresor + Carga de cristaloide

MEJORAR FLUJO UMBILICAL:

• Amnio-infusión

• Cambio posicional a la madre

PARTO:

• Evitar Prematurez, y trabajo de Parto

• Anestesia Regional para Cesárea

Int. J of Obst Anesthesia

2002, 11, 105-116

Intrauterine Resuscitation: Active

management of Fetal Distress JA Thurlow

Posición y Circulación Uterina

Efficacy of intrauterine resuscitation techniques in

improving fetal oxygen status during labor Simpson KR - Obstet Gynecol - 01-JUN-2005; 105(6)

Intrauterine Resuscitation: Active

management of Fetal Distress JA Thurlow, Int. J of Obst Anesthesia

2002, 11, 105-116

Birth Asphyxia and Cerebral Palsy

Jeffrey P. Phelan, MD

Clin Perinatol 32 (2005) 61– 76

Severe hyperoxaemia and severe

hypocapnia were associated with adverse

outcome in infants with post asphyxial HIE.

During the first hours of life, oxygen

supplementation and ventilation should be

rigorously controlled.

Do hyperoxaemia and hypocapnia add to the risk of

brain injury after intrapartum asphyxia? G Klinger, J Beyene, P Shah, M Perlman

Arch Dis Child Fetal Neonatal Ed 2005;90

ORIGINAL ARTICLE

Conclusions:

Current North American neonatal resuscitation guidelines recommend the use

of 100% inspired oxygen, whereas British guidelines suggest that ‘‘it may be

more appropriate to use an inspired oxygen concentration of 40% initially and

increase this if required’’.

Intrauterine resuscitation during labor: should maternal

oxygen administration be a first-line measure?

Simpson KR - Semin Fetal Neonatal Med, 01-DEC-2008; 13(6): 362-7

Recent evidence suggests potential risks to the mother and fetus or

newborn. Even small increases in maternal and fetal Po2 as a result

of maternal O2 administration can produce O2 free radical activity in

mothers and fetuses. The potential long-term effects are unknown.

Caution should be exercised when considering maternal O2

administration as a first-line intrauterine resuscitation measure

O2 was used in neonatal resuscitation from 1780, within 5 years of

its detection. It rapidly gained general acceptance and infiltrated

delivery rooms and, a century later, neonatal special care units.

After 217 years without scientific evidence, the use of O2 for

neonatal resuscitation has recently been questioned.

History of Neonatal Resuscitation - Part 2: Oxygen and Other Drugs Michael Obladen

Dept. of Neonatology, Charité Un. Medicine, Berlin, Germany

Neonatology 2009;95:91-96

Optimal Oxygen Saturation for Preterm Babies

Do We Really Know? The James Cook University Hospital, Middlesbrough, UK

Biol Neonate, Review, Win Tin, 2004;85:319-325

O2 is the most commonly used 'drug' in neonatal units as an

integral part of respiratory support.

The Indian Anaesthetists, October 2004(1), Dr. Sunanda Gupta MD

SUPPLEMENTARY OXYGEN ADMINISTRATION DURING REGIONAL

ANAESTHESIA FOR LSCS – IS IT JUSTIFIED?

1. There be no significant increase in the maternal – fetal O2 transfer rate

when O2 tension is raised on the maternal side, since with the increase

in O2 tension of the perfusing blood, there is probably a concomitant

vasoconstriction which negates any positive effects that might be

expected as a result of increasing the maternal-fetal O2 gradient.

2. Breathing high FiO2 modestly increased fetal

oxygenation, but caused a concomitant increase in O2

Free Radical activity in both mother and fetus.

Air versus oxygen for resuscitation of

infants at birth Tan A, Schulze A, O'Donnell CPF, Davis PG. Last Update:

09/12/2006

NICHD Cochrane Neonatal Home Page

Introduction to Neonatal Systematic

Reviews

Conclusión

Por lo tanto, sobre la base de la evidencia actualmente

disponible, si se elige el aire ambiental como gas inicial

para la reanimación, se debe seguir garantizando la

disponibilidad de O2 complementario.

Resuscitation of Newborn Infants with 21% or

100% Oxygen: An Updated Systematic Review

and Meta-Analysis

Systematic Review and Meta-Analysis

Vol. 94, No. 3, 2008, Ola Didrik Saugstad, M. Vento

Conclusions:

There is a significant reduction in the risk of neonatal

mortality and a trend towards a reduction in the risk of

severe hypoxic ischemic encephalopathy in newborns

resuscitated with 21% O2.

…coining the term ‘the oxygen radical disease of the newborn’ in which

he speculated that retinopathy of prematurity, bronchopulmonary

dysplasia, necrotizing enterocolitis, patent ductus arteriosus and

periventricular leukomalacia are different facets of one disease…

Recent Advances in

Neonatal Medicine

An International Symposium

Honoring Prof. Ola Didrik Saugstad

Würzburg, Oct 2–4, 2008

This magnitude of exposure to hypoxia in utero is rarely experienced in adult

life, with few exceptions, including severe pathophysiology in critical illness and

environmental hypobaric hypoxia at high altitude. Indeed, the lowest recorded

levels of arterial oxygen in adult humans are similar to those of a fetus and were

recorded just below the highest attainable elevation on the Earth’s surface: the

summit of Mount Everest. We propose that the hypoxic intrauterine environment

exerts a profound effect on human tolerance to hypoxia.

Cellular mechanisms that facilitate fetal well-being may be amenable to

manipulation in adults to promote survival advantage in severe hypoxemic

stress.

The human fetus develops in a profoundly hypoxic environment.

Thus, the foundations of our physiology are built in the most

hypoxic conditions that we are ever likely to experience: the womb.

Therapy for hypoxemic

critically ill adults:

potential therapeutic

targets

Concepts in hypoxia

reborn Daniel S Martin, Critical Care,

2010, 14:315

Goal-Directed Therapy for Severely Hypoxic Patients

With ARDS: Permissive Hypoxemia M. Abdelsalam MD, RESPIRATORY CARE, Nov, 2010 vol 55 No 11

Cuáles son los riesgos potenciales de la Hipoxemia Permisiva?,

Se tolera igual en todos los órganos y sistemas?

Órganos diferentes tienen tolerancia diferente a la hipoxemia. Por

ejemplo un cerebro sano, puede en general, tolerar mejor la

hipoxemia, a condición de que la perfusión cerebral se mantenga.

Permissive Hypoxemia

Is It Time To Change Our Approach?

Mohamed Abdelsalam, MD, CHEST / 129 / 1 / JAN,, 2002

2006

En general, la estrategia de hipoxemia permisiva

significa mantener el O2 entre 82 y 88% de SaO2