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Tiziana FruscaUniversità di Parma
Direttore UO Ostetricia e GinecologiaAzienda Ospedaliera Universitaria di Parma
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BASELINE RATE
- Bradycardia not accompanied by absentbaseline variability
- Tachycardia
BASELINE FHR VARIABILITY
- Minimal baseline variability
- Absent baseline variability with no recurrent decelerations
-Marked baseline variability
ACCELERATIONS
- Absence of included accelerations afterfetal stimulation
PERIODIC OR EPISODIC DECELERATIONS
- Recurrent variable decelerationsaccompanied by minimal or moderate baseline variability
-Prolonged deceleration more than2minutes but less than 10 minutes
-Recurrent late decelerations with moderate baseline variability
-Variable decelerations with othercharacteristics such as slow return to baseline, overshoots or shoulders
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Classificazione ACOG e severità della acidemia
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guidelines are silent on scenarios associated with fetaldamage, such as fever, chorioamnionitis, fetal systemicinflammatory response syndrome (FSIRS) and its noxioussynergistic interaction with hypoxia, fetal strokes, lack offetal cycling behaviour, maternal disease, and the recognitionof maternal heart rate (MHR) monitoring, to name afew.
tracking the evolution of fetaldefensive and compensatory responses to hypoxic ischaemic insults, then it should be possible, at least theoretically,to discriminate from a pool of ‘pathological’CTGs those etuses at genuine risk of acidosis and acidaemia (increased H+ in the bloodstream) or impaired neonatal adaptation from the subset that are no
BJOG 2014;121:1063–1070.
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• Intrapartum FHR interpretation—a step-wise physiologic approach
• Step 1—the normal and the abnormal initial CTG
• Step 2—recognition of the compensated and the decompensating fetus
– Slowly evolving hypoxia
– Subacute hypoxia
– Acute hypoxia (prolonged FHR deceleration and bradycardia)
The continuing focus on the morphological appearances ofFHR decelerations by current guidelines and training modulesdenies the clinician an understanding of how the fetusdefends itself, compensates for intrapartum hypoxic ischaemicinsults, and the ability to recognise the patterns that suggestloss of compensation.
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from “pattern recognition“to a “physiological interpretation”
• labor as a stress test
• oxytocin and prostaglandin : useful but potentially dangerous
• the most important question: “is the fetus able to cope?
• baroreceptor response and chemoreceptor response
• understanding what is happening and being able to predict next fetal adaptation
• the response is almost always not “to rush for a cesarean section”
• intrauterine resuscitation
REGOLAZIONE DEI BAROCETTORI
AUMENTO DELLA PRESSIONE ARTERIOSA
ENDOLUMINALE
STIRAMENTO RIDUZIONE DELLA FREQUENZA CARDIACA VASODILATAZIONE
PERIFERICA
REGOLAZIONE DEI CHEMOCETTORI
↓O2↑CO2↓pH
RISPOSTA CRONICA (IPOSSIA CRONICA):
↓ FREQUENZA CARDIACA
CHEMO-CETTORI
GLOMI AORTICI E GLOMI
CAROTIDEI
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Monitoring..means to monitor fetal hearth
AND CONTRACTIONS
WHY TO MONITOR
WHY TO MONITOR
• The oxigen and CO2
exchange from fetus to mother isinterrupted during a contractions(when the uterine pressure is 30mmHg or more), because aninterruption of the ematicplacental flow occurs• After a contraction, the fetusneeds 60 – 90 seconds to getagain to a normal oxygenation• The fetal ability to manage thelabour overall depends on hisability to rapidly get a normaloxygenation after thecontractions
Uterine contractionsand placental flow
Uterine contractionsand placental flow
- Oxygen extraction from other
tissues increased
- Reduction of non-essential
activities
Mechanism of fetal defence
- Sympathetic activities increased
- Ematic flow redistribution
- Anaerobic metabolism
Intact
- The fetus is able to react to
the acute hypoxia of the labour
Reduced
- Decrease in reserves for a fetus
who was healthy but was exposed
to a lot of hypoxial stimuli. Post-
term fetus
Absent
- Antenatal problems with
chronic distress. Mechanisms of
defence already used. IUGR
fetus.
- Optimal reaction to hypoxia
- Total compensation
- Reduced reaction to hypoxia
- Reduced compensation
- Minimal or absent reaction to
hypoxia
- Decompensation
- Fetal distress markers
- Low risk of asphyxial damage
- Variable markers of fetal distress
- Present risk of asphyxial damage
- Typical signs of fetal distress
missed
High risk of asphyxial damage
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• pro e contro CTG in travaglio di parto
• indicazioni nel basso rischio (cosa é il basso rischio?)
• come eseguire la cardiotocografia
• analisi del tracciato– dalla valutazione “gestaltica” (pattern recognition) alla interpretazione fisiopatologica
• classificazione del tracciato
• compiti e responsabilità della ostetrica/ compiti e responsabilità del medico
• decisioni cliniche
• il periodo espulsivo
Admission test
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• tracing acquisition:
– maternal position
– paper scales and speed
– external vs internal monitoring
– simultaneous maternal hearth rate
– monitoring twins
– storage of tracing
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speed velocity
The horizontal scale for CTG registration and viewing is commonly called “paper speed” and available options are usually 1, 2, or 3 cm/min.
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monitoring twins
• Continuous external FHR monitoring of twin gestations during
labor should preferably be performed with dual channel monitors that
allow simultaneous monitoring of both FHRs, as duplicate monitoring
of the same twin may occur and this can be picked up by observing
almost identical tracings.
. During the second stage of labor, external FHR monitoring of twins is particularly affected by signal loss, and for this reason some experts believe that the presenting
twin should preferably be monitored internally for better signal
quality. Other experts believe that external monitoring of both
twins is acceptable, provided that distinct and good quality FHR signals
can be obtained.
external monitoring
External FHRmonitoring is more prone to signal loss, to inadvertent monitoring of the maternal heart rate (Fig. 1) and to signal artifacts such as double-counting (Fig. 2) and half-counting ,
particularly during the second stage of labor.
external versus internal
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storage of tracing
patient name, place of recording, “paper speed,” and date and time when acquisition started and ended. digital CTG archives
Noi aggiungiamo nel timbro CTG:
nome dell’ostetrica PA e FC della donna, nome del medico che valuta il tracciato
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analysis of tracing
• baseline– normal baseline 110-160
– tachycardia > 160 10 minutes
• epidural analgesia, maternal pyrexia, betaagonist, parasympathetica
blockers, initial phase of non acute fetal hypoxemia
– bradycardia < 110 >10 min
• maternal hypothermia, betablockers,fetal arythmia, postdate pregnancies
• Variability
analysis of tracing
• accelerations increase of more 15 bpm more than 15 sec
– after 32-34 w establishment of fetal behavioural states : absence of accelerations during deep sleep for 50 minutes (cycling!!!)
– accelerations coincident with contractions especially in the second stage of labor suggest possible erroneous recording of the maternal hearth rate
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analysis of tracing
• The expulsive effort of women during the second stage of labour is associated with a maternal tachycardia and hence ‘accelerations’ of the fetal heart rate observed with contractions or maternal pushing during second stage must be viewed with caution
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analysis of tracing
• decelerations– early
– variable : baroreceptor mediated responce to increased arterial pressure seldom
correlated to acidosis
– but if Ushaped component, reduced variability, duration >3 min
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analysis of tracing
• late decelerations
– chemoreceptor mediated response to fetal hypoxemia when contraction are adequately monitored dec start more than 20 sec after the onset of contraction
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Acute hypoxia
• prolonged decelerations lasting more than 3 min chemoreceptor mediated component indicating acute hypoxia and acidosis and require emergent intervention -association with hypoxia /acidosis
• pH drops 0.01 every 1 min
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CTG classification
• ctg classification every 30 minutes
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actions in situations of suspected fetal hypoxia/acidosis
• excessive uterine activity
– stop oxytocine
– tocolysis
– stop pushing
• aortocaval compression
– change maternal position
– fluid administration
during the second stage of labor acidosis may develo more rapidly
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Second stage- periodo espulsivo
Il fatto di percepire l’espletamento del parto come temporalmente vicino, determina nel II stadio una maggior tendenza all’accelerazione sistematica dei tempi di fronte a tracciati CTG non rassicuranti o “indeterminati”. Questo si traduce in una sottovalutazione degli effetti deleteri della tachisistole, che non solo non viene “corretta” se presente, ma talvolta deliberatamente provocata mediante un utilizzo spesso indiscriminato dell’infusione di ossitocina, con un controllo meno rigoroso dei dosaggi rispetto al periodo dilatante. L’incitamento ad esercitare sforzi espulsivi vigorosi, su comando, a glottide chiusa e di durata prefissata, con l’intento di accelerare l’espletamento del parto si inserisce negativamente in questo contesto. (LG SLOG) Antonella Cromi
• nessuna delle principali classificazioni della cardiotocografia proposte da società scientifiche internazionali distingue il periodo dilatante dall’espulsivo
• la classificazione proposta da Melchior & Bernard nel 1972, rivista da Piquard nel 1988 dimostrato un valore prognostico
Misure correttive in presenza di CTG anomala in periodo espulsivo
Cosa viene fatto:
Si mette la donna in posizione litotomica
Si aumentano le contrazioni
Si incoraggia la donna a spingere ad ogni contrazione,
Si comincia a fare l’”appoggino”…
Spesso si crea panico
Cosa bisognerebbe fare:
Rallentare le contrazioni (ridurre la ossitocina!)
Far spingere la donna a spinte alternate
Far spingere in posizione laterale
Stimolare lo scalpo fetale
O2?? Liquidi??
“Calma e sangue freddo”
Take home messages
• La “demonizzazione” della cardiotocografia ha origini nel suo scorretto utilizzo, scorretta interpretazione e scorretta risposta
• L’outcome su cui valutare la sensibilità della cardiotococografia in travaglio non può essere la mortalità o la paralisi cerebrale
• L’ analisi dei tracciati secondo la pattern recognition determina errori nella valutazione prognostica
• La classificazione del tracciato deve esser ripetuta periodicamente analizzando tutte le sue componenti e confrontando con il primo tracciato
• Il tracciato va contestualizzato nella situazione clinica della madre e del feto
• Un tracciato classe 2 ACOG o sopetto FIGO non significa necessariamente un taglio cesareo o un parto operativo
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St.George’s management
Testo