Pathophysiology Flashcards
preterm
23-<37 weeks gestation
pregnancy term
37-42 weeks gestation
pregnancy show
vaginal discharge of mucous and blood
spontaneous rupture of membranes
gush of normally clear or pink fluid. Can occur prior to the onset of labour until the baby is born
meconium-stained amniotic fluid
greenish/brain-stained amniotic fluid
first stage labour
onset of regular painful contractions to full cervical dilation (i.e. contractions every 2-20minutes, 20-60 seconds duration)
Onset of painful regular, strong, rhythmic contractions resulting in dilation of the cervix until it is 10cm dilated cervix. The initial contractions are 15–30 minutes apart and 10–30 seconds in duration and can be felt at the fundus where they begin. Contractions eventually last 30-90 seconds and can come less than two minutes apart.
Crowning occurs
second stage labour
full cervical dilation to the birth of a baby (typical duration primipara 1-2 hours, multipart 15-45 minutes)
Imminent birth presentation
Imminent Delivery
- Active pushing/grunting
- Rectal pressure (urge to use bowels or bladder)
- Anal pouting
- Bulging perineum
- Urge to push
- Crowning (presenting baby’s head)
- mother’s statement “I am going to have the baby”
Precuoutate birth
usually rapid labour (less than 4 hours) with extremely quick birth). The rapid change in pressure from intrauterine life may cause cerebral irritation
causes of PPH
4 T’s
- tone: uterine atony ( a soft and weak uterus after childbirth)
- trauma: to genital structures
- tissue: retention of placenta or membranes
- Thrombin: coagulation
who is more at risk for PPH
- multiple pregnancy
- had more than 4 pregnancies
- past history of PPH
- history of APH
- large baby
Pathophysiology of pain:
A physiological and emotional response to a noxious stimulus with the potential to cause tissue damage. Pain is subjective and has two aspects, physiological and psychological. Pain stems from pain receptors detecting a painful stimulus and sending the message to the brain, allowing the relevant body parts and pathways to react with pain, swelling and other reactions. Each patient experiences pain differently, and different kinds of pain present in different ways, such as acute and chronic.
What are the major airway reflexes and what is their role in protecting the airway?
- Contraction of oropharyngeal muscles move food along. During swallowing, the epiglottis moves posteriorly against the glottis preventing food entering the trachea
- Protective reflexes in the upper airway help keep foreign bodies out
- A cough reflex stimulated by laryngeal and respiratory tract receptors involves forced exhalation against a closed glottis which then vigorously expels the air in the lungs as the glottis opens
- The gag reflex (also known as the pharyngeal reflex) – the muscles of the pharynx can contract if stimulated by an unwanted object in the throat producing a forceful expulsion to help prevent choking
- In some cases, the vocal cords within the glottis can close temporarily and occlude the airway from anything entering. This occurs early in drowning keeping water from getting past. When muscle tone is lost, the vocal cords relax and open fully allowing uncontrolled entry to occur where consciousness has been lost
What are the four different groups of airway obstruction that can be encountered?
Anatomical – positional:
- The tongue and epiglottis are designed to fall back and cover the glottis during swallowing. If consciousness is altered, this airway reflex loses its control since the tongue is a relatively large muscle
Anatomical – Infection or inflammation:
- Infection/inflammation within the upper airway can cause obstruction
Foreign body – external:
- This is an introduced foreign object from outside the body
Foreign bodies can become trapped by pushing the epiglottis down on to the glottis, by lodging within the glottis itself or, if small enough, pass beyond the glottis and lodge in the trachea or bronchi
Foreign body – internal:
- Gastric content is held in the stomach by sphincters and when these relax, when consciousness is lost, it allows the possibility of passive regurgitation (rather than active vomiting)
How may larger and obese patients be managed differently?
May require modified sniffing position to allow laryngoscopy since increased chest diameter impedes neck flexion.
Correct angle is achieved through ‘ramping’ by either stacking padding beneath the shoulders and head or, alternatively, raising the upper back of the bed/trolley to place the patient’s entire back into a semi-upright posture of approximately 25°.
Can you describe the clinical benefits of application of CPAP therapy to the patient presenting with acute pulmonary oedema?
- It supports inspiration (inspiratory positive airway pressure) and resists expiration (expiratory positive airway pressure)
- By retaining a small volume of air within the alveoli on expiration, they remain inflated. This has two critical advantages:
- They don’t have to be reopened each breath. This decreases the work of breathing dramatically
Also, alveoli that collapse don’t participate in gas exchange. Alveoli kept open do. All these together dramatically improve oxygenation
Describe the clinical benefits of application of CPAP therapy to the patient presenting with acute exacerbation of COPD
- As the COPD patient exhales, the gas escapes from the bronchi and trachea quite easily - low airway pressure. For gas on the distal side, in the alveoli, gas escapes slowly due to airway narrowing – higher airway pressure. Change in a pressure causes an obstruction point
- This increases airway pressure which keeps the alveoli inflated for longer, allowing expiration to occur
- The net result is more air can escape from the alveoli, more CO2 is removed and increased oxygen supplied with the next inspiration
hyperventilation
define COPD
Umbrella term categorised by chronic bronchitis, emphysema and chronic asthma. It’s an irreversible disease. Usually associated with cough, emphysema, airway damage, excessive mucus and sputum production. Depending on the specific disorder, emphysema or chronic bronchitis, the pathophysiology alters.
Chronic bronchitis:
define
When airways are constantly attacked by pollutants, such as those found in cigarette smoke, they become inflamed and filled with thick, sticky mucous.
Emphysema:
define
The exchange of oxygen and carbon dioxide takes place in the alveoli. When your alveoli are damaged or destroyed, it becomes difficult for the lungs to exchange oxygen and carbon dioxide and less oxygen gets into your body. Your lungs do not fully empty and air is trapped.
Patient presenting with COPD
oxygen levels
When treating COPD patients, titrate oxygen flow to stay between 88-92%, the normal range for a COPD patient. Consider low flow oxygen (e.g nasal prongs) to stay in this range. Treat as regular severe hypoxaemia if SpO2 <85%.
What is the purpose of endotracheal intubation?
- Et reaches further than an OPA/NPA
- Directs air directly into the trachea
- NPA/OPA directs air into the trachea to inflate the abdomen
- ET is direct ventilation to the lungs and prevents aspiration and vomit from getting into the airway compared to OPA/NPA/SGA
What is the difference between RSI and DSI?
Rapid sequence intubation (RSI)
- Medications administered simultaneously,
- Take effect quickly (within 1 minute),
- Intubation occurs immediately after.
- Prepare patient → Medications administered → Intubation
Delayed sequence intubation (DSI)
- Sedative agent administered early to assist patient compliance
- Intubation occurs several minutes after.
- DSI is typically for patients who cannot be adequately pre-oxygenated to allow safe intubation, i.e. a patient who is agitated or under the influence of psychostimulants.
- Sedation → improved compliance → prepare patient → intubation
What is the purpose of administering sedation prior to intubation?
- Sedation blunts mental awareness, via decreasing central nervous system (CNS) activity. This reduces sympathetic nervous system activity and the chance of the patient responding to the procedure, including discomfort, panic, anxiety along with physical responses of increased heart rate and blood pressure
- Eg. Ketamine, midazolam, fentanyl
What is the purpose of administering a muscle relaxant prior to intubation?
- What is the purpose of administering a muscle relaxant prior to intubation?
- Muscle relaxants aim to remove airway reflexes and motor activity
- Muscle relaxants, or paralysing agents, remove all skeletal muscle function. Arms, legs and, in particular, airway reflexes are stopped for the duration of the drug. The patient is unable to cough or gag and the vocal cords relax to allow intubation
- Eg. Rocuronium, suxamethonium
What is end tidal capnography (EtCO2)?
End tidal capnography (EtCO2) measures the proportion of carbon dioxide in exhaled air
EtCO2 monitors show two things:
a waveform of the CO2 escaping and
a numerical reading of the maximum amount of CO2 during each breath
What are some key functions of end tidal capnography?
EtCO2 monitoring can be used to evaluate effectiveness of ventilation
Ventilation rate and depth are calculated to approximate normal values (or in some cases intentionally abnormal values). This means a normal EtCO2 reading of 35-45 mmHg can be observed and maintained
It is considered the only definitive means to be sure the ET tube is correctly within the trachea
Why are the newborn first breaths so critical?
Opens alveoli for gas exchange
Decreasing intrapulmonary pressures
Decreases vascular resistance
Encourages greater blood flow into the pulmonary circulation
Breathing opens alveoli opens for gas exchange dramatically decreasing intrapulmonary pressures. This decreases vascular resistance encouraging greater blood flow into the pulmonary circulation increasing oxygenated blood flow returning from the pulmonary circulation to the left atrium and ventricle. Cardiac output and systemic blood pressure rise. The combination of cessation of blood through the umbilical cord and pulmonary and systemic pressure changes negate need for foetal circulation bypasses, encouraging their closure and transformation to newborn circulation. The absence of first breaths means much of the pressure changes necessary for circulatory evolution does not occur
Why is skin colour not helpful for immediate newborn assessment?
Healthy babies can look blue. Gas exchange is only just starting to build within the lungs even with immediate onset of spontaneous breathing. It can take several minutes for normal pulse oximetry values to be achieved in all babies
What is the role of APGAR in newborn assessment?
APGAR is NOT used as a guide for resuscitation. The APGAR system is a scoring tool for one and five minute post evaluation. Some of its components are far more indicative of need for resuscitation than others. Further, the time frames of when it is evaluated do not align at all with resuscitation need.
Do NOT wait one and five minutes to begin resuscitation!
What are the two key determinants to assess immediately following birth?
Is the newborn infant spontaneously breathing (or crying)?
Does the newborn infant have good muscle tone (is not floppy/flaccid)?
What are the principles guiding newborn cord cutting?
Wait several minutes or until cord stops pulsing to allow additional blood to increase newborns circulating volume.
However, cut the cord if there is a need to remove the newborn away from the mother to effect resuscitation.
Clamp at 10 cm distance from newborn. Place second clamp a further 5 cm. Cut in between the two clamps
Pathophysiology of asthma
Asthma is categorised by bronchoconstriction, chronic inflammation and increased mucus secretions. Asthma has an either an impaired autonomic control or inflammatory processes. Asthma is generally caused by an allergen which is detected by the body, such as smoke or dust, which then brings about a response. The pathogenesis of the disease is bought about by certain physiological mediators, such as histamine and prostaglandins. Once these inflammatory mediators are released, the body brings about a response which includes bronchoconstriction, chronic inflammation and increased music secretions.
APO
define
APO involves the accumulation of extravascular fluid in lung tissues and alveoli leading to ventilation/perfusion mismatch and an increased work of breathing. It is most commonly caused by congestive heart failure, normally left ventricular failure, but may also be attributed to non-cardiac causes. The consequence of this damage to the myocardium is a build-up of fluid within the pulmonary vasculature and a change in pressures within, leading to the movement of fluid from the intravascular space into the pulmonary space.
Seizure
define
A sudden, uncontrolled episode of excessive electrical activity within the brain, which can cause abnormal behaviour, altered conscious state, unnatural movement, impaired perception and altered sensations. It can be either focal or generalised in origin. Status Epilepticus: continuous/recurrent seizures with no return of consciousness between episodes. Can occur with any type of seizure and is considered a neurological emergency.
Time is important – by about 30 seconds after birth, the non vigorous newborn must have what commenced?
Getting the newborn breathing is the overwhelming intention. In the first instance, apply basic tactile (not rough) stimulation measures as a means of triggering muscle response and breathing
Pat dry the newborn incorporating foot tapping. Gentle but enough to provoke stimulation
Be wary of wet and slippery newborn!
Gently dry and wrap to maintain warmth as soon as practicable. Where resuscitation is being provided, consider methods to keep the newborn warm including warming the surrounding environment or heat lamp provision.
What must happen by 60 seconds post birth for the non vigorous newborn?
Place the head in the neutral anatomical position and commence ventilation with IPPV @ 40-60 minute
Do NOT add supplemental oxygen at this point – air resuscitation. The newborn requires ventilation and, at this point, is accustomed to poor arterial oxygenation and pulse oximetry
How is the heart rate determined in the non-vigorous newborn?
Auscultation is preferred over the ECG to avoid attaching electrodes to delicate skin – on right wrist due to it being the last place that is perfused
What is the role of airway suctioning in the non-vigorous newborn?
Suctioning can delay the necessary ventilation and oxygenation and can induce bradycardia. Only suction if airway obstruction is suspected. This occurs where there is difficulty in providing assisted ventilation but resistance is encountered. It also occurs where the newborn is attempting to breathe but appears to be having difficulty. This may be caused by airway obstruction.
Suction the mouth first, then the nose using a 10 or 12 FG catheter under low pressure ideally. Newborns are nasal breathers and may gasp and inhale any pharyngeal fluid. Use 5 second burst no deeper than the oropharynx
Why is body temperature maintenance critical for all newborns?
- Hypothermia increases oxygen consumption and impedes resuscitation
- Maintain newborn body heat and avoid heat loss. Remember the newborn is wet, naked and exposed to ambient air/breeze. Covering the newborn and addressing ambient air temperature is effective.
- Vigorous newborn – pat dry, lie skin to skin on mother. Maternal body heat is ideal. Cover both with blankets. Wrap the newborn as soon as practicable.
- Maintain normothermia – warm room, protect from breeze
- If resuscitation is required, ideally place the newborn on a warm surface and cover as best as possible to reduce heat loss. Place a protective cap on the newborn’s head to reduce heat loss
For the extreme preterm newborn (<28 weeks gestation) heat loss will be particularly easy and compromising. Do not dry the baby first. Place the newborn immediately inside a plastic zip lock bag with its head (pat dried) protruding
What amniotic fluid abnormalities can occur and what can they mean?
The cervix will eventually dilate sufficiently for the amnion to rupture and release amniotic fluid.
- Brownish/green stained fluid suggests meconium indicating foetal distress or a mature gut in a term baby.
- Heavily blood stained fluid may indicate antepartum haemorrhage.
- Offensive-smelling fluid suggests infection.
How can you tell the placenta is ready to be expelled?
Readiness for placental (third stage) is noted by a firm, round fundus at the umbilicus. A small fresh blood loss may be noted as the contracted uterus expels any blood within it. A lengthening of the umbilical cord might also be noted. This may be up to 30 minutes after birth. The mother will usually provide some feedback she is ready for third stage delivery including the return of the need to push and deliver the placenta. She will become uncomfortable and ask for the placenta to be delivered
What is the definition of primary post partum haemorrhage (PPPH)?
A small amount of blood loss post birth is normal. PPPH is more than 500ml of blood within 24 hours after birth, usually within minutes. Blood loss can be deceptive and difficult to estimate. Bleeding that appears fast or is requiring multiple towels to mop up should be considered seriously and quickly
How does primary post partum haemorrhage differ from secondary?
Secondary PPH pertains to period 24 hours to six weeks post birth – usually relates to infection or retained tissue post birth – this instruction does not cater for this problem
What are the usual causes of primary PPH?
- Tone - Atonic uterus (soft/weak) – most common cause - this is when your uterine muscles don’t contract enough to clamp the placental blood vessels shut. This leads to a steady loss of blood after delivery.)
- Trauma – concealed (uterine, cervical, vaginal) or visible perineal tear
- Bleeding disorder – if take mediation that encourages clotting (hear) - (If you have a coagulation disorder or pregnancy condition like eclampsia, it can interfere with your body’s clotting ability. This can make even a tiny bleed uncontrollable)
- Retained tissue post-birth - retained placental tissue: This is when the entire placenta doesn’t separate from your uterine wall. It’s usually caused by conditions of the placenta that affect your uterus’s ability to contract after delivery.
Why do we use Tranexamic acid for PPH?
It reduces bleeding by inhibiting the enzymatic breakdown of fibrin
Why do we use oxytocin in PPH
Oxytocin stimulates uterine muscles to contract
- Oxytocin is released from the posterior pituitary and increases uterine contractions by stimulating prostaglandin production and increasing intracellular calcium ion levels in myometrial cells (The muscular outer layer of the uterus)
define shoulder dystocia
Shoulder dystocia refers to a situation where, after delivery of the head, the anterior shoulder of the fetus becomes impacted on the maternal pubic symphysis, or (less commonly) the posterior shoulder becomes impacted on the sacral promontory.
