Week 101 Diarrhoea Flashcards

Question

Where is the peritoneal surface absent? | Histology

Answer 1

oesophagus and rectum, which are intra-thoracic and pelvic structures respectively

Answer 2

``` Squamous epithelium • Basement membrane • Lamina propria • Muscularis mucosae • Submucosa , superficial nerve plexus, glands • Muscularis propria Inner circular muscle Myenteric nerve plexus Outer longitudinal muscle • Adventitia (fat) ```

Answer 3

``` Surface mucous cells • Neck or foveolar region • Parietal cells and chief cells in glands surrounded by lamina propria • Muscularis mucosae • Sub-mucosa • Muscularis propria circular, oblique nerve nerve plexus longitudinal • Serosa ```

Answer 4

``` • Surface mucous cells • Mucous glands in lamina propria • Muscularismucosae • Submucosa • Muscularis propria Inner circular muscle nerve plexus Outer circular muscle • Serosa ```

Answer 5

* Villi covered by columnar epithelium * Crypts/glands * Lamina propria surrounds glands and fills villi * Muscularis mucosae * Submucosa * Muscularis propria (inner circular, nerve plexus, outer longitudinal) * Serosa

Answer 6

``` Lamina propria and crypts/glands • Muscularis mucosae • Submucosa • Muscularis propria (inner circular, nerve plexus, outer longitudinal) • Serosa ```

Answer 7

Metal; bone, calcium Soft tissue; fluid, liver Fat Gas

Answer 8

``` Foreign bodies Kidney stones Abdominal masses (e.g. right renal mass) Bowel obstruction (e.g. dilated small bowel) Perforation (e.g. triangles of free gas) ```

Answer 9

Good: - Liver, spleen, kidneys, bladder, gallbladder Bad: - Bowel, bone

Answer 10

Gallstones | Masses

Answer 11

``` Bone +700 Liver +30 Water 0 Fat -50 Gas. -700 ``` (and kidney/spleen/aorta/large bowl/small bowl/bladder/rectum)

Answer 12

Images based on how much water is in the tissues.

Answer 13

T2 weighted- bright water | T1 weighted- bright fat

Answer 14

Cirrhosis Liver metastasis Polycystic kidneys Enlarged prostate

Answer 15

Rotavirus Norovirus Astrovirus Enteric adenovirus

Answer 16

- Leading cause of gastroenteritis worldwide - Infects nearly all children throughout the world during early childhood; peak incidence of infection ages 6-24 months -  Causes up to 40% of all cases of severe diarrhoea in infants -  In the USA, rotavirus is the leading cause of hospital admissions for AD - Infection occurs during the winter months in temperate climates, but perennially in tropical countries - >7 antigenic groups (A – G) with group A being the most common worldwide; multiple different serotypes within each group (important for vaccine development) - Shed in high titers in stools (therefore infectious to contacts) for up to 21 days after onset of symptoms - Transmission via fomites (toys, hard surfaces) increases disease spread within families and institutions - Vaccine available and used in some countries

Answer 17

- Second most common cause of severe AD in children in industrialized countries - Most common cause of outbreaks of AD, typically during winter months and in closed communities such as restaurants, schools, day care centers, hospitals, and cruise ships - Highly contagious - Transmission is by direct person-to-person spread, through contaminated food and also through vomit

Answer 18

-  Cause sporadic AD, mainly in young children -  More common in winter months -  Cause outbreaks in institutions - May be shed in the stool for several weeks after the illness, and longer in immunocompromised children

Answer 19

Causes AD throughout the year, primarily in younger children

Answer 20

- Campylobacter - Salmonella - Diarrhoeagenic - Escherichia coli (E. coli) - Cholera - Shigellosis - Typhoid (Salmonella typhi and S. paratyphi; “enteric fever”) - Clostridium difficile

Answer 21

-  Present in the gastrointestinal tract of wild and domestic birds and animals (therefore, faeces of these animals are a source of infection) -  Transmission by contaminated water, undercooked poultry, unpasteurized milk, direct person-to-person -  Faecal shedding of bacteria persists for 2-3 weeks - Second most common cause of travelers’ diarrhoea, after enterotoxigenic E. coli (ETEC)

Answer 22

-  Highest infection rates in infants and young children -  Present in the gastrointestinal tract of animals and reptiles, including pets - Transmission mainly via contaminated animal foods (poultry, eggs, dairy products, beef, fish) - Faecal shedding persists for several weeks, especially in younger children, and can be prolonged by antibiotic therapy; 1% cases become chronic carries (faecal shedding > 1 year)

Answer 23

- Five main strains of E. coli cause diarrhoea: Enterotoxigen (ETEC), Enterohemorrhagic (EHEC), Enetropathogenic (EPEC), Enteroinvasive (EIEC) and Enteroaggerative E. coli (EAEC) - Transmission is from contamination of food (especially undercooked meat and unpasteurized milk) and water with human or animal faeces, or direct contact with an infected case or carrier - EHEC o Most common cause of diarrhoea in U.S., especially E. coli O157:H7 which is highly contagious o Shed in cattle faeces o Occurs sporadically and in outbreaks o Associated with haemolytic-uraemic syndrome (HUS) ETEC - Causes hundreds of millions of cases of AD and tens of thousands of deaths of infants and younger children in developing countries every year  - The major cause of diarrhoea in travelers to countries with poor sanitation

Answer 24

- Endemic in many countries with poor sanitation and lack of safe water in Africa, Asia, and South and Central America - Occurs in outbreaks, especially following contamination of water supplies during natural disasters, wars and civil unrest

Answer 25

-  Four species: Shigella (S.) sonnei, S. flexneri, S. boydii and S. dysenteriae -  Endemic in countries with poor sanitation - Causes severe dysentery (blood and mucus in the stools) mainly in children under age 5 -  also infects travelers -  highly infectious - Humans are the reservoir of infection, and transmission is through direct person-to-person contact (including sexual contact), fomites, and contaminated food and water -  Houseflies may also transmit after feeding on infected faeces -  Faecal shedding persists for a few weeks; chronic carriage is rare

Answer 26

Endemic in South and South-East Asia, Africa, South America and Eastern Europe

Answer 27

- Present in the soil and common in the environment - Commensal organism in the gut of up to 50% of healthy infants but <5% of older children and adults - Diarrhoea associated with secretion of toxins A and B which may be life threatening, especially in the elderly ``` - Outbreaks occur within health care institutions – major cause of health-care acquired diarrhea (along with norovirus) ``` -  3 major risk factors: recent antibiotic use, admission to hospital and age >65 years. Use of PPIs is also likely to be a risk factor – through compromised gastric acid barrier

Answer 28

Giardiasis Cryptopsoridium parvum Entamoeba histolytica causes diarrhoea and dysentery in developing countries

Answer 29

 Occurs worldwide  Most common cause of parasitic diarrhoea in developed countries  Humans are the main reservoir but infection also occurs in dogs, cats, and other animals  Transmission is through direct person-to-person contact or ingestion of resistant cysts in contaminated water and food  Excretion of cysts in faeces may persist for several months

Answer 30

- Occurs worldwide - Carried by mammals, birds, and reptiles  Transmission occurs from livestock, zoo animals, and pets -  Extensive outbreaks occur following contamination of water supplies -  Outbreaks in nurseries associated with high attack rates -  Common cause of traveler’s diarrhoea

Answer 31

Presenting complain What is the main problem?

Answer 32

History of presenting complaint Detailed description of the problem

Answer 33

Direct questions Responses to specific questions relevant to the PC Important positive and negative information

Answer 34

Important symptoms in each of the major | systems (cardiovascular, respiratory, etc.)

Answer 35

Past medical history What illnesses and hospital admissions have occurred in the past? Concurrent illnesses.

Answer 36

Drug history: Recent and current treatment

Answer 37

Known allergies e.g. latex/drugs

Answer 38

Developmental milestones- Developmental milestones Immunisations Family history Social history and employment Smoking/alcohol Travel history

Answer 39

``` General appearance Systems Summary of problem Working diagnosis Differential diagnosis Management plan Name, sign, date, GMC number ```

Answer 40

WHO* definition of diarrhoea: – 3 or more loose or watery stools (taking the shape of the container) in a 24-hour period – Acute: <14 days duration – Persistent: ≥14 days duration

Answer 41

small volume, bloody, mucoid stools + abdominal pain / toxicity

Answer 42

– Stool frequency | – Stool consistency; ± blood, mucus

Answer 43

- sunken eyes

Answer 44

- Osmotic - Secretory - Inflammatory

Answer 45

Stool volume: moderately increased Response to fasting: diarrhoea stops Stool osmolality: Normal to increased Ion gap: > 100 mOsm/kg

Answer 46

Stool volume: very large Response to fasting: diarrhoea continues Stool osmolality: normal Ion gap: < 100 mOsm/kg

Answer 47

- Disordered structure and function - Damage to the SI mucosa (digestion and absorption) - Symptoms: – Pain – Bloody, mucoid stools – Weight loss Main Causes: • Infection – esp. bacterial pathogens • Auto-immune disease – inflammatory bowel disease • Food sensitivity (Coeliac, CMP) • Other – e.g. radiation

Answer 48

Infection caused by e.g. cholera, rotavirus, ETEC

Answer 49

Malabsorption: CHO/protein- lactose intolerance Rapid gut transit- IBS, toddler diarrhoea, stimulant laxative Osmotic laxative- lactulose, PEG

Answer 50

Malabsorption of fat- e.g. pancreatic disease or coeliac disease

Answer 51

Inflammatory bowl disease e.g. Crohn's, UC Dysentery e.g. shigella, campylobacter Other- radiation enteritis

Answer 52

– Excess loss of fluid → dehydration | – Loss of electrolytes → disordered physiology

Answer 53

– Loss of nutrients → malnutrition if prolonged

Answer 54

– Excess loss of fluid → dehydration – Loss of electrolytes → disordered physiology – Loss of nutrients → malnutrition if prolonged – Energy consumption – Mucosal damage: GIT haemorrhage, perforation, gut derived sepsis

Answer 55

IBS: “Spastic colon” or “functional diarrhoea” - increased gut motility Management: - reassurance • anti-spasmodics • anti-diarrhoeals caused by osmotic, neuronal, possible low-grade inflammation

Answer 56

Rotavirus diarrhoea RNA virus; multiple diarrhoea mechanisms Diagnosis: stool virology Management: ORF (self- limiting after 4-5 days)

Answer 57

Giardiasis Steatorrhoea Diagnosis: microscopy of x3 fresh stool specimens Management: tinidazole or metronidazole

Answer 58

Traveller’s diarrhoea ``` Enterotoxigenic Escherichia coli (ETEC) • Attaches to mucosa and produces toxins • Severe but usually self limiting • Clinical diagnosis ```

Answer 59

Clostridium difficile • Gram positive, spore forming bacillus • Enterotoxins A and B • Typically older in-patients exposed to antibiotics in last 8 weeks • Highly infectious: barrier nursing • Wide spectrum of disease from self-limiting to severe colitis Most severe form: – pseudomembranous colitis – multiple elevated yellow/white plaques up to 20 mm across Diagnosis: faecal toxin; sigmoidoscopy Treatment: metronidazole / vancomycin; faecal enema

Answer 60

``` Airways Breathing Circulation- hydration status Disability Don't forget glucose ```

Answer 61

Enteral (oral; NGT) rather than parenteral fluids - much safer

Answer 62

if • suspected or confirmed shock • deterioration despite ORS solution • persistent vomiting of ORS solution given orally or via a nasogastric tube

Answer 63

Administer O2 • Establish IV (or IO) line • Give rapid IV infusion of 20 mls/kg body weight of 0.9% sodium chloride* • Frequent monitoring of clinical response • Repeat if signs of shock persist but also consider causes of shock other than dehydration (e.g. sepsis)

Answer 64

Intra-osseous line inserted into e.g. tibia

Answer 65

Normal saline because high salt and high chloride but no potassium

Answer 66

``` Overhydration: • Increasing heart rate • Respiratory distress / cough • “Crackles” in the lung fields • Hepatomegaly (enlargement of the liver) • Oedema (e.g. peri-orbital swelling) ``` Hypernatreamic dehydration • Serum Na+ >150 mmol/L • Suspectif – jittery movements – increased muscle tone – increased reflexes (hyperreflexia) – convulsions – drowsiness/coma Fluid management is as described above, but •replace the fluid deficit more slowly – over 48 rather than 24 hrs •Reduce serum Na+ slowly (aim for <0.5 mmol/L/hour) •Measure serum Na+ frequently to guide management

Answer 67

- appears unwell/deteriorating - altered responsiveness (e.g. irritable, lethargic) - decreased urine output - skin colour unchanged - warm extremities - sunken eyes - dry mucous membranes (except for mouth breather) - tachycardia - tachypnoea - normal peripheral pulses - normal capillary refill time - reduced skin turgor - normal blood pressure

Answer 68

- decreased level of consciousness - pale or mottled skin - cold extremities - tachycardia - tachypnoea - weak peripheral pulses - prolonged capillary refill time (normally 2 secs) - hypotension (decompensated shock)

Answer 69

• After rapid fluid infusion for shock, add 100 mL/kg/day for fluid deficit replacement to maintenance IV fluid requirement • If treatment of shock was not required, add 50 mL/kg/day for fluid deficit replacement to maintenance fluid requirement • Use 0.9% saline or 0.9% saline with 5% dextrose • Measure plasma Na+, K+, urea, creatinine and glucose regularly and adjust fluid therapy accordingly • Add K+ to parenteral fluids if serum level is low • Attempt to introduce ORS solution early and gradually. Stop parenteral fluids once ORS solution tolerated • Frequent monitoring of clinical response

Answer 70

• Continue breastfeeding and other milk feeds • Encourage fluid intake • Avoid fruit juices and carbonated drinks • Offer ORS solution as supplemental fluid to those at increased risk of dehydration* • Use low-osmolarity ORS solution (240–250 mOsm/l) *Infants and children at increased risk of developing dehydration • age <1 year, esp. <6 months • infants who were low birth weight • > 5 loose stools in past 24 hours • vomited > twice in past 24 hours • additional fluids either not offered or not tolerated • infants who have stopped breastfeeding during the illness • signs of malnutrition

Answer 71

During rehydration therapy • continue breastfeeding / give full-strength milk • do not give solid foods After dehydration corrected • reintroduce the child's usual solid food • avoid fruit juices and carbonated drinks until the diarrhea has stopped

Answer 72

Compared with industrialised countries, the epidemiology and context of acute diarrhoea in children in poorer countries is characterised by: •more frequent episodes of diarrhoea - up to 6-7 episodes/child/year •more severe diarrhoea (greater electrolyte loss) and greater frequency of bacterial diarrhoea •increased host susceptibility – especially malnutrition, vitamin A and zinc deficiencies and HIV infection •management is usually by non-doctor, first-level staff and occurs with few resources (therefore, simplified guidelines) Although the principles of management are the same, WHO recommendations for management differ to account for these differences.

Answer 73

Severe acute malnutrition: ``` Muscle wasting and reduced subcutaneous fat • Angular stomatitis • Tongue - smooth • Conjunctival and palmar pallor • Skin: hypo- and hyper- pigmentation ```

Answer 74

Anthropometry

Answer 75

* Clinical signs of shock and dehydration unreliable | * Parenteral fluids can cause severe deterioration

Answer 76

SAM: sunken eyes, but moist conjunctivae and hypersalivation (sore mouth) → NOT dehydrated (Note angular stomatitis + perineal ulcertion

Answer 77

The pump fails and results in increased total body [Na]. Also K+ lost in diarrhoea.

Answer 78

Risks •Total body Na+ high •Reduced cardiac reserve to cope with fluid bolus •Impaired endothelia – fluid leaks from circulation Danger! Parenteral fluids may cause heart failure and death • Oral fluids preferred to parenteral • If required, IV fluids administered cautiously • Use lower Na+ concentration (e.g. 0.45% saline) • Switch ASAP to reduced osmolarity ORS solution (ReSoMal: 37.5 mmol/L Na; 40 mmol/L K)

Answer 79

fundus--> body--> antrum--> pyloric sphincter-->duodenum--> jejunum (leaky, mech: Na-nutrient/Na-H) --> ileum (moderately leaky, mech: Na-Cl, Na-nutrient, Na) --> cecum (moderately tight)--> proximal colon--> distal colon (obviously it's not completely this)

Answer 80

Anatomy designed to amplify the surface area in order to expand the interface of luminal contents with enterocytes. •The microvillus membrane has a surface area 600-fold larger than a simple cylinder with the diameter of the small intestine Duodenum: - very leaky - absorbs 8L (saliva/bile/pancreatic secretions/gastric secretion/diet) - absorbs calcium and iron Jejunum: - loses 7L - very leaky - darker than ileum ileum: - loses 1.5L and 1L to colon - moderately leaky - absorbs bile salts and vit b12

Answer 81

superior, descending (where bile duct and pancreatic ducts drain into), inferior, ascending

Answer 82

indigestible carbohydrates (fibre), bile acids, vitamin B12·IF, water, and electrolytes

Answer 83

in the ileum by specialized transport systems

Answer 84

They are absorbed in the ileum

Answer 85

- goblet cells - absorptive cells - crypt cells - paneth cells - M cells - endocrine, caveolated and cup cells

Answer 86

Goblet cells contain clear mucin granules. Mucus secretion serves a protective role. Denser in the proximal intestine, and sparser on the villus tip.

Answer 87

have well-developed microvilli

Answer 88

smaller, with fewer, less-developed microvilli and narrow apices

Answer 89

found in the base of the crypt. Contain eosinophilic secretory granules. More common in the ileum than in the jejunum. Probably involved in intestinal barrier function

Answer 90

found over Peyer's patches. Rapidly transport luminal macromolecules and some microorganisms by transcytosis. Probably important for processing and presenting antigen to mucosal immune system.

Answer 91

Rapid, continuous, and coordinated process. Anchored stem cells give rise to proliferative cells of the crypt. As the cells migrate from the crypt to the villus, they stop dividing and become more differentiated. Exfoliation occurs as mature cells are shed into the intestinal lumen. Apoptosis, or programmed cell death, is integral to maintaining the cellular balance in the crypt:villus unit. Apoptosis may also serve to remove genetically abnormal cells early in the course of differentiation. In the small intestine, apoptosis has been demonstrated in the area adjacent to the stem cell. By contrast, in the colon, apoptosis occurs more distantly from the stem cells, at the surface, some abnormal cells escape apoptotic control.

Answer 92

•Barriers separating hostile, variable environment of the intestinal lumen from carefully controlled subepithelial space. •Mucus - viscous hydrated gel, binds bacteria. •Secreted immunoglobulin A - binds bacterial antigens. •Bicarbonate - neutralizes luminal acid. Together make the unstirred layer - functional diffusion barrier. •Apical membrane of the epithelial cells is the greatest barrier. Lipid bilayer of the plasma membrane is a barrier to hydrophilic solutes, but allows diffusion of hydrophobic molecules. •Membrane proteins are necessary for entry of hydrophilic solutes into the cell. •Paracellular pathway provides a low electrical resistance shunt around cells and blocks the movement of macromolecules around cells

Answer 93

Role in carbohydrate digestion and absorption. Indigestible carbohydrates partially broken down by enzymes in colonic bacteria to short-chain fatty acids (acetate, propionate, and butyrate), absorbed by the colonic mucosa. Short-chain fatty acids are important substrates for mucosal cells in the colon. Colon may serve in carbohydrate salvage in patients with carbohydrate malabsorption (eg, short- bowel syndrome with retained colon). About 80 g of nondigested or nonabsorbed carbohydrate can be converted to short-chain fatty acids by bacteria and absorbed by the colon

Answer 94

Many fewer microvilli than in small intestine Prominent glycoprotein overlies microvilli stops bacteria attaching e.g. e.coli

Answer 95

Chloride is transported into the cell via the concerted actions of the Na+, K+, Cl- exchanger (A) and the Na+, K+- ATPase. Active chloride secretion is stimulated by cyclic AMP (cAMP) or increases in intracellular calcium, which then serve to normalize intracellular Cl-

Answer 96

In secretory diarrhoea, electrolyte absorption lower, so that sodium, potassium, and their counterions account for most of the osmoles in stool water.

Answer 97

In osmotic diarrhoea, electrolyte absorption is normal - measured ions account for only a fraction of the osmoles in stool water

Answer 98

Sum of the concentrations of ions and small molecules must equal plasma osmolality, usually 290 mOsm/kg

Answer 99

The colonic lumen has a luxuriant flora - assists in fermentation of the faecal material, suppresses overgrowth of pathogens, affects hydration status and weight of the individual, alters stool pH, and degrades intestinal mucins. In the colon there is a gradient in numbers of organisms ranging from 106/mL in the caecum to 1012/mL in the rectum.

Week 101 Diarrhoea Flashcards

(126 cards)