Peri-op Care: Post-op Complications 2 Flashcards
what is the usual cause of immediate PONV?
Side effect of general anaesthesia or post-op analgesia, esp. opiates.
suggest possible causes of PONV >48 hrs after surgery
- paralytic ileus
- mechanical obstruction, e.g. fibrous adhesions (can occur within 4 days and often requires further operation), faecal impaction
- electrolyte disturbances, uraemia, hypercalcaemia…
describe the 2 CNS structures involved in nausea and vomiting
- chemoreceptor trigger zone (4th ventricle) - responds to stimuli in circulation (located outside BBB), sends info to vomiting centre
- vomiting centre (medulla oblongata) - receives input from chemoreceptor trigger zone, GI tract, vestibular system and higher cortical structures (e.g. sight, smell and pain) and acts on diaphragm, stomach and abdo muscultature to control and coordnate movements involved in vomiting
suggest prophylactic measures to reduce PONV
- anaesthetic measures: reduce opiates and volatile gases, avoid spinal anaesthetics
- prophylatic anti-emetic therapy, esp. if opiate use
- dexamethasone (8 mg) at induction of anaesthesia
suggest possible drugs used in management of PONV
- Pts with impaired gastric emptying/gastric stasis (unless bowel obstruction suspected): prokinetic agents, e.g. metoclopramide or domperidone (dopamine antagonists)
- Suspected metabolic/electrolyte imbalance or cytotoxic agents: metoclopramide
- Opioid-induced PONV: ondansetron (5-HT3 R antagonists) or cyclizine (H1 histamine R antagonist)
what is the DDx for a pt with post-op dyspnoea?
Respiratory causes:
- basal atelectasis
- bronchopneumonia
- PE
- pneumothorax
- aspiration of gastric contents
- lobar collapse
- ARDS
- exacerbation of pre-existing chronic lung condition
Cardiac causes:
9. LV failure (e.g. result of MI or fluid overload)
which Ix would you perform on a pt with post-op dyspnoea?
A-E assessment +/- call senior
- basic obs: HR, RR, O2 sats, BP, temp.
- bloods: FBC, CRP, ABG - look for signs of infection (+ blood culture is suspected sepsis)
- ECG - ?arrythmia or MI
- CXR
how and when would a pt with atelectasis present?
Uusually <48 hrs post-op.
Features:
- dyspnoea
- tachypnoea with shallow breathing
- decreased O2 sats.
- may have fine crackles over affected pulmonary tissue
how would you manage a pt with post-op basal atelectasis?
- deep breathing exercises and chest physiotherapy (ensures airways are opened maximally and coughing can be performed effectively)
- Ensure adequate analgesia
- If no improvement following physiotherapy, bronchoscopy can help suction out pulmonary secretions (not routinely performed).
what is ARDS? when can it occur?
ARDS = form of acute lung injury characterised by severe hypoxaemia in absence of cardiogenic cause. Can affect any adult pt (e.g. medical, surgical or obstetric).
Occurs when there is inflammatory damage to alveoli, leading to pulmonary oedema, respiratory compromise and ultimately, acute respiratory failure.
describe the Berlin definition of ARDS.
1) Acute onset within 7 days.
2) PaO2:FiO2 ratio <300
3) Bilateral infiltrates on CXR
4) Alveolar oedema not explained by fluid overload or cardiogenic causes
suggest direct and indirect causes of ARDS
Direct:
- pneumonia
- smoke inhalation
- gastric aspiration
- fat embolus
- DIC
- near-drowning
Indirect:
- sepsis
- acute pancreatitis
- polytrauma
- RICP
Describe the clinical features of ARDS
- Hx of relevant injury
- worsening dyspnoea
- cyanosis
- tachypnoea and tachycardia
- peripheral vasodilation
- bilateral fine inspiratory crackles
how would you manage a pt with ARDS?
Admit to ITU for respiratory and circulatory support, likely require emergency intubation and mechanical ventilation.
