PBL Topic 4 Case 1 Flashcards
Identify four roles of the GI tract
- Movement of food through the tract
- Digestion, aided by secretion of digestive juices
- Absorption of water, electrolytes and digestive products
- Circulation of blood through to carry away the absorbed subsances
Identify the five layers of the intestinal wall from the outer surface inward
- Serosa
- Outer longitudinal muscle layer
- Inner circular smooth muscle layer
- Submucosa
- Mucosa
Outline the dimensions and arrangmeent of a smooth muscle fibre in the GI tract
- 200 to 500 micrometres in length
- 2 to 10 micrometres in diameter
- Fibres are arranged as bundles in parallel fibres
What is the role of gap junction between muscle fibres in each bundle?
- Allow low-resistance movement of ions from one muscle cell to the next.
Why is the smooth muscle of the GI tract described as a syncytium?
- Muscle fibre bundles fuse at various points
- Action potential travels in many directions as a result
What are slow waves?
- Undulating changes in the resting potential of about 5 to 15 millivolts
What is the role of interstitial cells of Cajal and how are they arranged?
- Electrical pacemakers of smooth muscle cells
- Which interact with smooth muscle cells to excite the appearance of spike potentials
- Form a network with each other and have synaptic-like connections with smooth muscle cells
What are the frequencies of slow waves in the stomach, duodenum and ilium?
- Stomach: 3 per minute
- Duodenum: 12 per minute
- Ilium: 9 per minute
What is the resting membrane potential of GI smooth muscle cells?
- -55 mV
When does a spike potential occur? (with reference to changes in membrane potentials)
- When the resting membrane potential becomes more positive than -40 mV
Identify two ways in which the spike potential in a GI smooth muscle cell differs to that in a nerve fibre
- Influx of calcium as well as sodium through calcium-sodium channels
- Longer duration due to slow closure of calcium sodium channels
What is the frequency of spike potentials?
- 1 to 10 per second
How long does each spike potential last?
- 10 to 20 milliseconds
Outline the process of smooth muscle contraction
- Calcium binds to calmodulin
- This complex activates myosin kinase
- Myosin kinase phosphorylates regulatory chain on myosin head causing it to bend with actin
Why are slow waves not involved in smooth muscle contraction?
- They do not cause calcium ions to enter the smooth muscle fibre
What is meant by tonic contraction?
- Continuous contraction not associated with basic electrical rhythm
Identify three causes of tonic contraction
- Continuous repetitive spike potentials
- Hormones that cause depolarisation of smooth muscle
- Continuous entry of calcium ions into the cell
What is meant by unitary smooth muscle? Identify three places in which it is found
- Thousands of muscle fibres contract as a single unit
- GI tract, ureters, uterus, bile duct, blood vessels
What is the embryological origin of the enteric nervous system?
- Neural crest cells
How many neurones is the enteric nervous system composed of?
- 100 million (same as spinal cord)
Where is the myenteric plexus located and what does it control?
- Between outer circular and inner longitudinal smooth muscle
- Controls GI movements
Where is the submucosal plexus located and what does it control?
- Submucosa
- Controls GI secretion and blood flow
Identify three effects of stimulation of the myenteric plexus
- Increased tonic contraction
- Increased intensity of rhythmical contraction
- Increased rate of rhythmical contraction
Describe the inhibitory functions of the myenteric plexus and its regulation
- Inhibit of intestinal sphincter muscles
- Regulated by vasoactive intestinal polypeptide
Identify three effects of stimulation of the submucosal plexus
- Intestinal secretion
- Local absorption
- Local contraction of submucosa
What are the main excitatory and inhibitory neurotransmitters secreted by enteric neurons?
- Excitatory: ACh
- Inhibitory: Noradrenaline, adrenaline
From which cranial nerves does the parasympathetic nervous system arise?
- Vagus
- Glossopharyngeal
- Facial
- Oculomotor
From which spinal nerves does the parasympathetic nervous system arise?
- S2
- S3
- Occasionally S1 and S4
The majority of parasympathetic nerve fibres travel through which nerve?
- Vagus nerve
Identify eight organs supplied by the vagus nerve
- Oesophagus
- Stomach
- Small intestine
- Proximal colon
- Liver
- Gallbladder
- Kidneys
- Upper portion of ureters
Identify four organs supplied by the sacral parasympathetic fibres
- Descending colon
- Rectum
- Bladder
- Lower portion of ureters
Which neurons in the parasympathetic nervous system are cholinergic? Where are the ganglia located?
- Both preganglionic and postganglionic
- Distally close to effector organ
How does glandular secretion in different parts of the GI differ in terms of innervation?
- Glands in the upper GI tract are mainly controlled by parasympathetic fibres
- Glands in the lower GI tract are controlled by local factors and enteric nervous system
Identify three ways that parasympathetic stimulation increases GI motility
- Promoting peristalsis
- Relaxing of sphincters
- Increased glandular secretion
From which spinal cord segments does the sympathetic innervation of the GI tract arise?
- T5
- L1
- L2
How are the preganglionic neurons and ganglia of the sympathetic nervous system arranged?
- Preganglionic neurons enter sympathetic chain
- To pass through ganglia which are located proximally, distant from the effector organ
Identify two sympathetic ganglia located in the GI tract
- Celiac ganglion
- Mesenteric ganglia
Which neurons in the sympathetic nervous system are cholinergic and which are adrenergic?
- Preganglionic: Cholinergic
- Postganglionic: Adrenergic
Outline the effect of sympathetic stimulation on GI motility and identify two mechanisms that cause this effect
- Reduces GI motility (inhibition of peristalsis and increases tone of sphincters)
- Effect of noradrenaline on intestinal tract smooth muscle
- Inhibitory effect of noradrenaline on neurons of the enteric nervous system
Identify three types of GI reflexes
- Reflexes integrated within gut wall
- Reflexes from gut to sympathetic ganglia and back to gut
- Reflexes from gut to spinal cord or brainstem and back to gut
What is the gastrocolic reflex?
- Signals from stomach to cause evacuation of colon
What is enterogastric reflex?
- Signals from colon and small intestine to inhibit stomach motility and secretion
What is colonoileal reflex?
- Signals from colon to inhibit emptying of ileal contents into colon
Which cells secrete gastrin?
- G-cells of antrum of stomach
When is gastrin released?
- Distension of stomach
- Products of proteins
- Gastrin releasing peptide
(Following ingestion of a meal)
What are the primary effects of gastrin?
- Stimulation of gastric acid secretion
- Stimulation of growth of the gastric mucosa
Which cells secreted cholecystokinin?
- I cells of mucosa of duodenum and jejunum
When is cholecystokinin released?
- In response to digestive products of fat, fatty acids and monoglycerides
- Which are present in the intestinal contents
Identify 3 effects of cholecystokinin
- Contracts gallbladder which expels bile
- Relaxation of sphincter of Oddi which allows bile to mix with and emulsify fatty substances
- Inhibition of muscle contraction in stomach, producing time for fat digestion
Which cells secrete secretin?
- S cells in mucosa of duodenum
When is secretin released?
- In response to gastric acid juice emptying into duodenum from pylorus of stomach
What are the primary effects of secretin?
- Promotes pancreatic secretion which neutralises the acid in small intestine
Where is gastric inhibitory peptide secreted from?
- Mucosa of upper small intestine
When is gastric inhibitory peptide released?
- In response to amino acids in the duodenum
What are the primary effects of gastric inhibitory peptide?
- Decreasing motor activity of stomach
- Slowing emptying of gastric contents into duodenum when small intestine is overloaded
Where is motilin secreted from?
- Upper duodenum
What are the primary effects of motilin?
- Increases GI motility
- By stimulating waves of motility called inter digestive myoelectric complexes every 90 minutes
Where is glucose dependent insulinotropic peptide released? When is it released and what are its primary effects?
- Small intestine
- In response to glucose
- Stimulates insulin secretion
What is peristalsis?
- Wave-like propulsive movements in GI tract
Identify three stimuli of peristalsis
- Parasympathetic signals
- Distension of gut wall
- Chemical or physical irritation
What is the effect of atropine on peristalsis?
- Reduced peristalsis
- Paralysis of cholinergic nerve terminals
- Of myenteric plexus
Why does peristalsis die out in the orad direction?
- Myenteric plexus is polarised in the anal direction
How far can each contractile ring push intestinal contents?
- 5 - 10 cm
What is receptive relaxation?
- Gut relaxes downstream towards anus
- Allowing food to be propelled more easily in this direction
What is meant by Starling’s law of the gut?
- Refers to myenteric reflex / peristaltic reflex
- And movement in the anal direction
Identify two causes of mixing movements in the GI tract
- Peristalsis against a closed sphincter
- Local intermittent constrictive contractions
What does hunger determine?
- The amount of food that a person ingests
What does appetite determine?
- The type of food to ingest
What is meant by satiety?
- Desire to limit food intake
- After ingesting a satisfying amount of food
Stimulation of which nuclei results in hyperphagia?
- Lateral hypothalamic feeding centre
Stimulation of which nuclei results in aphagia?
- Ventromedial hypothalamic satiety centre
What is the role of serotonin in appetite regulation?
- Inhibits the lateral hypothalamic feeding centre
- Which alters the appetite set point (baseline for caloric and nutrient intake)
How do levels of serotonin differ in anorexics and bulimics differ?
- Raised in anorexia
- Reduced in bulimia
Identify four signals that the hypothalamus receives from elsewhere in the body that influence feeding behaviour
- Sensory information about stomach filling
- Chemical signals from nutrients in blood
- Hormones released by adipose tissue
- Signals from cerebral cortex (sight, smell, taste)
What are orexinergic and anorexigenic substances in relation to feeding?
- Orexigenic stimulates feeding
- Anorexigenic inhibits feeding
Identify two anorexigenic neurons of the arcuate nuclei
- POMC neurons (Pro-opiomelanocortin)
- CART neurons (cocaine- and amphetamine-related transcript)
Identify two orexigenic substances
- Neuropeptide Y (NPY) acting on Y1 and Y2 receptors
- Agouti-related protein (AGRP)
What do POMC neurons release and to which receptors does this chemical bind?
- Alpha-Melanocyte Stimulating Hormone (a-MSH)
- Binds to MCR-3 and MCR-4 in paraventricular nuclei
What are the biochemical and physiological effects of AGRP neurons?
- Competitive inhibitor of a-MSH
- As it binds to MCR-3 and MCR-4
- Resulting in excessive feeding and obesity
What is the effect of cholecystokinin on feeding?
- Activation of melanocortin pathway in hypothalamus
- Causes release of a-MSH from POMC and CART neurons acting on MCR-3 and MCR-4 receptors of paraventricular nuclei
- Resulting in reduced feeding
Identify a hormone that stimulates AGRP neurons
- Ghrelin
Identify 3 hormones that inhibit AGRP neurons / excite POMC/CART neurons
- Insulin
- Leptin
- CCK
Identify four glands that secrete saliva
- Parotid glands
- Submandibular glands
- Sublingual glands
- Small buccal glands
How many mL of saliva is produced each day?
- Between 800 and 1500 mL
Identify two major types of saliva secretion and what each type contains
- Serous secretion containing ptyalin, an alpha amylase, for starch digestion
- Mucus secretion containing mucin, a glycoprotein, for lubrication and protection
How does secretion type vary between the salivary glands?
- Parotid: mainly serous
- Sublingual and submandibular: both types
- Buccal glands: mainly mucus
What is the pH of saliva?
- Between 6.0 and 7.0
Which ions are most prominent in saliva?
- Potassium
- Bicarbonate
What occurs in the primary stage of salivary secretion?
- Acini secrete ptyalin and/or mucin
- Reabsorption of sodium from salivary ducts
- Secretion of potassium ions in exchange for sodium
Why is chloride absorbed passively from the salivary ducts?
- Excess sodium reabsorption over potassium secretion
- Creating an electrical negativity of -70 mV in the ducts
What occurs in the secondary stage of salivary secretion?
- Bicarbonate ions are secreted by ductal epithelium
- This is caused by passive exchange of bicarbonate ions for chloride ions
What are the concentrations of sodium, chloride, potassium and bicarbonate in saliva?
- Sodium: 15 mEq/L
- Chloride: 15 mEq/L
- Potassium: 30 mEq/L
- Bicarbonate: 60 mEq/L
Identify 4 ways that saliva helps to maintain healthy oral tissue
- Flow of saliva washes away bacteria and food (removing bacterial support)
- Lysosomes attack bacteria and digest food (removing metabolic support)
- Thiocyanate ions are bactericidal
- Secretory IgA can destroy bacteria
Identify the role of saliva in digestion of carbohydrates
- a-amylase hydrolyses 5% of starch into maltose
Why is salivary starch activity blocked in the stomach?
- Gastric acid secretions have a low pH
- Amylase becomes nonactive below a pH of 4.0
Which division of the autonomic nervous system regulates salivary secretion?
- Parasympathetic nervous system
What is the role of the superior salivatory nuclei?
- Innervates submandibular and sublingual glands
- Via the submandibular ganglion from the chorda tympani, a branch of the facial nerve
What is the role of the inferior salivatory nuclei?
- Innervates parotid gland
- Via the otic ganglion from the tympanic branch of the glossopharyngeal nerve
Identify five factors that increase salivary secretion
- Sour taste (acids)
- Smooth objects
- Pleasant smelling food (links to olfactory cortical areas)
- Reflexes caused by Irritating foods (helps to dilute the substance)
- Increased blood supply
Outline the vasodilator effect of saliva on blood vessels
- Salivary cells secrete kallikrein
- Which splits a2-globulin to form bradykinin
- Which is a strong vasodilator
What is the character of oesophageal secretion?
- Mucous which provides lubrication for swallowing
Identify two types of glands in the oesophagus
- Simple mucus glands superiorly prevent mucosal damage by food
- Compound mucus glands inferiorly prevent damage by acidic gastric juice
What is the importance of mastication in relation to fruits and raw vegetables?
- Fruits and vegetables which have indigestible cellulose membranes
- Which must be broken down before the food can be digested
What is the importance of mastication in relation to digestive enzymes?
- Digestive enzymes only work on the surface of food particles
- Chewing food increases surface area for digestive enzymes
What is the importance of mastication in relation to protection of the GI tract?
- Chewing food breaks it down into a fine particulate consistency
- Which prevents excoriation of the GI tract
- And increases the ease with which food is emptied form the stomach into the small intestine
What are the roles of incisors and molars? What are the relative forces each type of tooth can be closed by jaw muscles?
- Incisors provide a strong cutting action, 25 KG
- Molars provide a grinding action, 90 KG
Identify four muscles of mastication and the function of each
- Masseter, elevation of mandible
- Temporalis, elevation and retraction of mandible
- Medial pterygoid, elevation and lateral movements of mandible
- Lateral pterygoid, protrusion and lateral movements of mandible
Identify the innervation of the muscles of mastication
- Mandibular branch of trigeminal nerve
What is the role of the buccinator muscle? What is its innervation?
- Contraction presses the cheek against the teeth
- Which keeps the cheek taut and aids in mastication
- By preventing food from accumulating between the teeth and cheek.
- Facial nerve
Identify the three nuclei that receive sensory innervation during mastication and the type of information each recieves
- Mesencephalic nucleus: proprioceptive from spindle-rich muscles of mastication
- Chief nucleus: tactile information of food in mouth
- Spinal nucleus: nociceptive information
What is the jaw-closing reflex?
- Contact of food with oral mucous membrane activates jaw-closing motor neurones so that the teeth are brought to occlusion
What is the jaw-opening reflex?
- Activation of stretch afferents due to dental occlusion
- Which inhibits closure motor neurons and activates jaw openers
What is another term for swallowing?
- Deglutition
Identify the three stages of swallowing and a brief description of each
- Voluntary stage, which initiates swallowing
- Pharyngeal stage, involuntary stage which allows passage of food from pharynx into oesophagus
- Oesophageal stage, involuntary stage which transports food from oesophagus to stomach
Identify the muscles involved in the voluntary stage of swallowing and the role of each
- Orbicularis oris: adducts the lips to form a tight seal
- Superior longitudinal muscles: elevates the tongue to make contact with hard palate to propel bolus posteriorly
Where are epithelial swallowing receptors located and which nerve do they stimulate?
- Tonsillar pillars
- Glossopharyngeal nerve
How does stimulation of epithelial swallowing receptors result in contraction of muscles of the palate, pharynx and larynx?
- Information is relayed via glossopharyngeal nerve to nucleus solitarius
- Which relays information to nucleus ambiguus
- Which contains motor neurons that innervate muscles of palate, pharynx and larynx
What is the role of levator veli palatini in the pharyngeal stage of swallowing?
- Elevates soft palate to close the posterior nares
- Which prevents food enter nasal cavities
What is the role of the superior constrictor muscle in the pharyngeal stage of swallowing?
- Adducts the palatopharyngeal folds
- Forming a sagittal slit
- Which allows food that is masticated enough to pass with ease
- Impeded posterior movement of large objects
What is the role of the lateral cricoarytenoids, oblique and transverse arytenoids during the pharyngeal stage of swallowing?
- Adduction of vocal folds
- Causing epiglottis to swing backward over laryngeal inlet
- Which prevents passage of food into the trachea
What is the role of the digastric and stylohyoid muscles during the pharyngeal stage of swallowing?
- Elevates the hyoid bone
- Which lifts the larynx upwards
- Resulting in enlargement of the opening of the oesophagus
- Also lifts the glottis out of the stream of food flow
What is the role of the constrictor muscles during the pharyngeal stage of swallowing? When is this function performed?
- Sequential contraction which propels food by peristalsis into oesophagus
- Occurs once the larynx is raised AND upper oesophageal sphincter becomes relaxed
What is the cricopharyngeus and when is it open?
- Lowest part of the inferior constrictor
- Which only opens for the advancing bolus
How long is the entire pharyngeal stage of swallowing?
- Less than 6 seconds
What are the two peristaltic movements that occur during the oesophageal stage of swallowing?
- Primary peristalsis: simple continuation of peristaltic wave that begins in oesophagus
- Second peristalsis: caused by distension of oesophagus when primary peristalsis fails
What are the neural mechanisms involved in secondary peristalsis during the oesophageal phase of swallowing?
- Intrinsic neural circuits in the myenteric nervous system
- Reflexes that begin in pharynx that are transmitted via vagus nerve to medulla and back again to oesophagus via glossopharyngeal and vagus nerve
How does innervation in the upper third of the oesophagus differ to that in the lower third?
- Musculature in upper third is skeletal muscle and is innervated by skeletal nerve impulses from CN9 and CN10
- Musculature in lower third is smooth muscle and is innervated by CN10 and also myenteric plexus
Outline receptive relaxation in relation to the lower oesophageal sphincter and its regulation
- Relaxation of LOS ahead of peristaltic wave
- Which allows easy propulsion of swallowed food into stomach
- Regulated by nitric oxide and serotonin
Aside from regulation of food into the stomach identify another role of the lower oesophageal sphincter
- Helps to prevent reflux of stomach contents into the oesophagus
What is dysphagia?
- Difficulty swallowing
- A sensation of obstruction during the passage of solid or liquid through the pharynx or oesophagus
Identify a disease of the tongue or mouth that can result in dysphagia
- Tonsilitis
Identify two neuromuscular disorders that can result in dysphagia
- Bulbar palsy
- Myasthenia gravis
Identify three oesophageal motility disorders that can result in dysphagia
- Achalasia
- Scleroderma
- Chagas’ disease
Identify three causes of external pressure that can result in dysphagia
- Goitre
- Mediastinal glands
- Enlarged left atrium
Identify three intrinsic lesions that can result in dysphagia
- Foreign body
- Stricture
- Rings and webs
Identify three abnormalities that can occur when the swallowing mechanism is paralysed
- Complete abrogation of swallowing so that swallowing cannot occur
- Failure of the glottis to close to that food passes into the lungs instead of the oesophagus
- Failure of the soft palate and uvula to close the posterior nares so that food refluxes into the nose
Describe the negative effects of impairment of swallowing mechanism during anaesthesia
- Unconscious patients often vomit
- Vomit is sucked into trachea because anaesthesia has blocked swallowing mechanism
- Patients either choke to death on their vomit or it results in aspiration pneumonia (Mendelson’s syndrome)
A patient suffers from intermittent slow progression of dysphagia, with a history of heartburn, suggest the most likely diagnosis
- Benign peptic stricture
A patient suffers from relentless progression over a few weeks, suggest the most likely diagnosis
- Malignant stricture (carcinoma)
A patient suffers from slow onset of dysphagia for solids and liquids at the same time, suggest the most likely diagnosis
- Achalasia
What is the investigation of choice for swallowing difficulties?
- Endoscopy
Which investigations may be carried out if no abnormality is found using endoscopy?
- Barium swallow with video fluoroscopic swallowing assessment
- Oesophageal manometry where a catheter is inserted through nose into oesophagus and the pressure generated within the oesophagus is measured
How do the symptoms of oropharyngeal and oesophageal dysphagia differ?
Oropharyngeal dysphagia: difficulty initiating swallowing, chocking + aspiration
- Oesophageal: food sticking after swallowing + regurgitation
Outline the pathology of achalasia
- Damage to myenteric plexus in lower third of oesophagus resulting in reduction of ganglion cell numbers
- LOS remains spastically contracted
- So food cannot enter stomach for many hours
- Oesophagus becomes enlarged and becomes infected during long periods of stasis
Outline the epidemiology of achalasia
- 1:100,000
- Equal in males and females
- Occurs at all ages but rare in childhood
Outline the clinical features of achalasia
- Intermittent dysphagia for solids and liquids
- Regurgitation of food, particularly at night, aspiration pneumonia is a complication
- Spontaneous chest pain due to oesophageal spasm
- Ulceration resulting in substernal pain
What does a CXR show in achalasia?
- Dilated oesophagus
- Fluid level seen behind heart
- Fundal gas shadow is absent
What does a barium swallow show in achalasia?
- Lack of peristalsis
- Synchronous contractions, sometimes with dilation
- Birds beak due to failure of sphincter to relax
When is oesophagoscopy used in achalasia?
- To exclude a carcinoma at lower end of oesophagus
- Patients must have a 24-hour liquid only diet to remove food and debris
Identify the treatments used for achalasia
- Heller’s operation: surgical division of LOS
- Nifedipine and sildenafil
- Endoscopic dilatation using a hydrostatic balloon
- Botulinum toxin A
What is the success rate of endoscopic dilatation of the LOS in achalasia
- 80%
- 50% require a second dilatation within 5 years
Outline the MoA of botulinum toxin A
- Inhibition of calcium dependent release of ACh from presynaptic terminal
- Countering effect of selective loss of inhibitory neurotransmitters
- Resulting in relaxing of LOS
Identify one complication of achalaisa
- Squamous carcinoma of oesophagus
What is an oesophageal web? Where do they most occur and which type of imaging is most appropriate for viewing them?
- Thin membranous flap covered with squamous epithelium
- Anteriorly in the postcricoid region of the cervical oesophagus
- Barium Swallow
Identify a cause of an oesophageal web
- Plummer-Vinson Syndrome (Paterson-Brown-Kelly Syndrome) associated with glossitis and angular stomatitis
- Chronic iron deficiency anaemia
- Treated with iron
Identify two types of oesophageal rings
- Mucosal / Schatzki / B ring located at the squamocolumnar mucosal junction
- Muscular / A ring located proximal to the mucosal
Identify the treatments for oesophageal rings
- Reassurance
- Dietary advice
- Dilatation may be necessary
What is an oesophageal diverticulum?
- Abnormal pouch at a weak point in the wall of the GI tract
Where does a Zenker’s diverticulum / pharyngeal pouch occur?
- Upper oesophageal sphincter through the fibres of cricopharyngeus
What is Killian’s dehiscence and what is its clinical significance?
- A weakness in Zenker’s diverticulum
- That allows a pulsion diverticulum
- Which will collect food which may regurgitate into the mouth or lungs
Where does a traction diverticulum occur? Identify the cause
- Middle of the oesophagus
- Inflammation associated with diffuse oesophageal spasms or mediastinal fibrosis
Where does an epiphrenic diverticulum occur, what condition is it associated with?
- Just above the LOS
- Achalasia
Outline the investigation and treatments of choice in oesophageal diverticulum
- Barium swallow (since endoscopy may enter or perforate the pouch)
- Myotomy and resection of the pouch
Identify two causes of oesophageal infections and their presentation
- Candida (white plaques)
- TB (ulceration and mediastinal lymphadenopathy)
Identify two treatments of oesophageal infections given to patients on large doses of immunosuppressive agents
- Nystatin
- Amphotericin
- Both of which are macrolide antifungal antibiotics
Identify the epidemiology, clinical features and treatment of eosoinophilic oesophagitis
- Common in children (atopic)
- Dysphagia and chest pain
- Fluticasone, budesonide syrup (glucocorticoids)
- Elimination diets (more beneficial in children)
Outline the pathology of aspiration pneumonia
- Aspiration of gastric content into lungs
- Intense destruction due to gastric acid
Which lobe is most likely to be affected by aspiration pneumonia
- Right middle lobe
Which type of bacteria is most responsible for aspiration pneumonia
- Anaerobes
Outline the treatment of aspiration pneumonia
- Co-amoxiclav
- Which covers gram-negative and anaerobes
- Until specific cultures are obtained
Oesophageal cancer is [A]th most common cancer worldwide
- [A] = Sixth
Identify the two types of oesophageal cancer
- Squamous cell carcinoma
- Adenocarcinoma
Where is squamous cell carcinoma of the oesophagus most common? Identify five risk factors
- Africa, China, Iran
- Alchohol
- Tobacco
- Red and processed meat
- Low fruit and vegetable
- Obesity
Where is adenocarcinoma of the oesophagus most common? Identify two risk factors
- Western countries
- Barret’s oesophagus
- Gastroesophageal reflux disease
How does the location of an oesophageal squamous cell carcinoma and an adenocarcinoma differ?
- SCC: Upper oesophagus
- AC: Lower oesophagus in columnar epithelium
Outline 4 clinical features of oesophageal cancer
- Progressive painless dysphagia or solids which progresses to fluids
- Weight loss
- Anorexia
- Lymphadenopathy
Outline the investigations used in oesophageal cancer
- Endoscopy provides histological and cytological proof of adenocarcinoma
- Barium swallow for differential diagnosis (motility disorder)
- CT for metastasis
- Endoscopic ultrasound for determining depth of penetration of tumour
What are the criteria for endoscopy for oesophageal cancer?
- Performed within 2 weeks
- It patient is suffering from dysphagia
- Or is over 55 and suffering from weight loss/ upper abdominal pain/reflux/dyspepsia
Outline the main treatments of cancer of the oesophagus
- Surgery if tumour has not infiltrated outside oesophageal wall
- Chemotherapy (cisplatin, 5-fluorouracil) if stage 2b/3
- Palliative: endoscopic laser therapy / expanding metal stents to improve QoL
What fraction of patients are affected by undernutrition in hospital? Who is most likely at risk?
- 1/3
- Elderly
Identify 4 physical effects of undernutrition
- Impaired immunity
- Muscle weakness
- Delayed wound healing
- Increased risk of post-operative infection
Identify the four steps of managing undernutrition in hospital
- Normal diet (with food chart)
- Supplements (high energy and protein drinks)
- Enteral tube feeding (nasogastric tube)
- Parenteral nutrition (PIC, central line)
Why is the enteral route preferred?
- Preserves integrity of mucosal barrier
- Reducing risk of bacteraemia
- Reduces risk of multi-organ failure
What type of tube is used for short-term enteral feeding?
- Nasogastric tube
What type of tube is used for enteral feeding where there is gastric outlet obstruction or gastric stasis?
- Nasojujunal tube
What type of tube is used for long-term enteral feeding, why?
- Percutaneous endoscopic gastrostomy
- More comfortable due to less irritation to nasal mucosa and tube is less likely to be pulled out
Identify the main danger of gastrostomy
- Inadvertent puncture of intra-abdominal organs
- Causing peritonitis and bleeding
When is parenteral nutrition used? Why is it typically a last resort?
- When enteral feeding is impossible
- Expensive
- Higher risk of complications
Identify four routes for parenteral tube feeding
- Peripheral venous cannula
- Peripheral inserted canula (20cm)
- Peripherally inserted central catheter (60cm)
- Central line, via subclavian route due to lower infection rates
Which routes of parenteral tube feeding allow for hyperosmolar solutions to be used?
- Peripherally inserted central catheter
- Central line
Outline 4 complications of parenteral tube feeding
- Septicaemia due to line infection (importance of aseptic technique)
- Hyperglycaemia (main component is glucose)
- Fluid and electrolyte disturbances (re-feeding syndrome)
- Hypercalcaemia
- Rare allergic reactions to lipid
What percentage of stroke victims require home enteral tube feeding?
- 2%
Outline the pathology of refeeding syndrome,
- Nutrition is given to undernourished patient
- Rapid conversion from a catabolic state to an anabolic state
- Release of insulin, leading to cellular uptake of phosphate, potassium and magnesium ions
- Which provoke falls in serum levels
Identify one serious consequence of refeeding syndrome
How is Refeeding syndrome treated?
- Cardiac arrhythmia
- I.V Pabrinex (containing high strength Vitamin B and C)
When should artificial nutrition be given?
- When it would be of overall benefit to the patient
- Including patients who lack capacity (to whom nutirtion would be of overall benefit)
- And incapacitated patients who are not expected to die within hours or days
- Or incapacitated patients who are expected to die within hours or days and have specifically requested it be provided
What should doctors do before withdrawing nutrition or hydration from a patient in a PVS?
- Consult courts
What is the importance of DNACPR
- Aims to ensure patient dies a dignified death in a peaceful manner
When is DNACPR generally appropriate
- When it is clinically inappropriate
- CPR will be unsuccessful or there are potential burdens and risks
- Or cardiac or respiratory arrest is part of dying process
How should doctors handle DNACPR when the patient lacks capacity?
- Consult views of healthcare team
- Consult legal proxy
When should CPR be performed?
- If the cause reversible e.g. induction of anaesthesia
- In clinical emergencies where there is no DNACPR in place
How should doctors respond to patients who ask for information that might encourage or assist them in ending their lives
- Explain that it is a criminal offence to encourage or assist suicide
What is meant by passive euthanaisia
- Withholding or withdrawing life-extending treatment e.g. antibiotics, nutrition, hydration
What is meant by active euthanasia?
- Direct inducement of death e.g. administering overdose of painkillers
What is voluntary euthanasia?
- Patient expresses informed consent and wishes for someone to assist them in the dying process
What is speculative euthanasia?
- Individual assumes consent when consent cannot be given (comatose, infant, or dementia)
What is involuntary euthanasia?
- Patient refuses consent and does not wish to die
What is indirect euthanasia?
- Providing treatment to reduce pain
- Whose side effects speed patients death
- Doctrine of double effect
What is assisted suicide?
- Providing someone the means of killing themselves e.g. putting painkillers within reach
What is the role of the coroner?
- Investigate all deaths where the cause is unknown or may not be due to natural causes
Identify four roles of death certification
- Provide explanation to families about how they died (implication for future generations)
- Enable family to register death to allow disposal of body and settlement of estate
- Public health interventions
- Measure exposure of risk factors
Who is responsible for issuing the death certificate?
- Doctor who cared for patient within last 14 days
What categories of death must be reported to a coroner before the death is registered?
- Accident
- Suicide
- Violence
- Neglect
- During or shortly after operation/anaesthesia
- During or shortly after police or prison custody
How is a death certificate written?
- 1a: Immediate cause of death
- 1b / c: Sequence of events that led to death on subsequent lines
What should be avoided on a death certificate?
- Old age
- Natural causes
- Organ failure
Outline Leventhal’s self regulatory model
- Illness is dealt with in the same way as other problems
- Problem or change in status quo motivates one to solve the problem and re-estalbish normality
- Interpretation: Confronted with problem which will lead to a desire to return to normality
- Coping: Coping strategies that should lead to normality
- Appraisal: Have strategies been effective and has normality been achieved?
Identify 5 factors that affect QoL
- Physical health
- Psychological state
- Level of independence
- Social relationships
- Relationship to the salient environmental features
What is a standards needs approach to QoL measures?
- Assumes that needs rather than wants are central to quality of life
What is a psychological-process approach to QoL measures?
- Considers QoL to be constructed from individual evaluations of personally salient aspects of life
Give an example of a unidimensional measure on a health questionnaire
- Focuses on one aspect of health
- E.g. ‘how is your mood?’
Give an example of a multidimensional measure on a health questionnaire
- Focuses on health in broadest sense
- E.g. ‘how is good your health?’
Define absolute poverty
- Denotes a poverty level relative to a fixed standard of living, rather than the resign of the population.
Define relative poverty and what classifies as poor and severe poverty
- Compares each household income to the median income of their country
- Where those with less than 60% of the median income classified as poor
- Where those with less than 40% classed as severe poverty.
Define material deprivation
- When an individual is not able to afford certain possessions that most people take for granted.
Define worklessness and how does it related to the concept of ‘life chances’?
- When no one in a household is in work.
- Predictor of ‘life chances’ along with income, material deprivation and educational attainment at 16
Identify four causes of poverty
- Unemployment / low paid work
- Inadequate benefits
- Lack of affordable housing
- Demographic factors e.g. disability, family size, BAME group
Identify effects of poverty at each stage of life
- Children: More likely to suffer chronic disease such as asthma
- Adult life: More likely to suffer from long term conditions e.g. COPD, diabetes, hypertension
- Later life: Poorer emotional wellbeing, mental and physical health
Why is the relationship between poverty and health described as bidirectional?
- Unemployment and poverty can contribute to poor health (social causation)
- Poor physical and mental health also increases the likelihood of unemployment (social drift)
- And the two can become mutually reinforcing
Outline inverse care law
- Availability of good medical or socialcaretends to vary inversely with the need of the population served
Identify 5 actions to prevent poverty
- School funding: early interventions, whole child approach
- Jobs: More jobs, greater flexibility, minimum income for health living
- Reduce fuel poverty and education people on improving their energy efficiency
- Doctors: Advocate for health needs of their patients (commissioning responsibilities)
- Sufficient supply of affordable housing
What is persistent poverty?
Persistent poverty is defined as when an individual experiences relative low income in the current year, as well as at least two out of three preceding years.
