Midterm Flashcards
1.Approach to the Surgical Patient
- Chief complaint
- History of present illness
- pain
- vomiting
- change in bowel habits
- hematemesis,rectal bleeding
- trauma
- Past Medical history
- drugs,ROS
- Past surgical history
- OB/GYN history
- Social and family history
1.1.Approach to the Surgical Patient
- Physical examination
- Elective surgical examination
- Examination of body orifices
- <c>ABCDE
<ul>
<li>
<strong>C</strong>atastrophic Haemorrhage control</li>
<li>
<b>A</b>irway (cervical spine control when appropriate)</li>
<li>
<strong>B</strong>reathing</li>
<li>
<b>C</b>irculation</li>
<li>
<strong>D</strong>isability</li>
<li>
<strong>E</strong>xtremity-environment-exposure</li>
</ul>
</c>
1.2.Approach to the Surgical Patient
- Provisional diagnosis
- most probable diagnosis so far
- Differential diagnoses
- list of probable diagnoses to rule out
- Lab & other studies
- blood tests
- urine tests
- functional studies : ECG etc
- Imaging test
- X-ray
- ultrasound
- CT,MRI
- Special investigations
- colonoscopy
- angiography
- cytoscopy
2.Types of Healing
Primary healing (first intention)
- Tissue is clean
- Reapproximation with sutures
- Healing without complication, minimal scarring
Secondary Healing (second intention)
- Infected wounds & burns
- Open wound
- Formation of granulation tissue
Delayed primary closure (third intention)
- Secondary healing for 5 days
- Then primary closure
3.Granulation Tissue
- Red,moist,granular tissue
- Appears during healing of open wounds
- Microscopy : collagen, new blood vessels, fibroblasts, inflammatory cells
- Healing achieved by creation of scar tissue
4.Wound Healing
Hemostasis & Inflammation
- 0-5th day after injury
- Platelet aggregation to exposed subendothelial collagen (IGF-1,TNFa,b, PDGF)
- Coagulation cascade: fibrin clot⇒ coagulation &scaffolding
- Chemotaxis : Damaged endothelial cells ⇒ activation of complement components
- Inflammatory cells :
- Neutrophils & monocytes 24-48h : rolling and adhesion
- Macrophages 48-96h
- T-lymphocyes peak at 7 days
4.1.Wound Healing
Proliferation
- 4-14 days
- Fibroblast replication
- Platelets release PDGF,IGF-1,TGFb
- Macrophages and fibroblasts release FGF,IGF-1,VEGF,IL-1,2,8, PDGF, TGFa,b
- Fibroblasts produce collagen and proteoglycans
4.2.Wound Healing
Angiogenesis
- 2nd to 4th day after injury
- Response to chemoattractants from platelets and macrophages
- PDGF,FGF,TNFa,b,VEGF
4.3.Wound Healing
Epithelization
- starts from wound edges
- Low PO2⇒TGFb from epithelial cells⇒blocks differentiation and promotes mitosis
- Wound needs to be moist to promote epithelization
- Exudate contains : growth factors and lactate
4.4.Wound Healing
Maturation & Remodeling
- 8d-months
- Fibroblasts replace fibrin ECM with collagen monomers⇒polymerization and cross-linking
- ECM evolution : fibronectin, collagen III,glycosaminoglycans,proteoglycans,collagen I
- Remodeling⇒collagen lysis and turnover (MPPs)
- Collagen deposition>>collagen lysis
- Fibroblasts attach to collagen fibres⇒wound contraction
- Negative effect of contraction⇒deformation,stricture
- Wound stretching if tension>>contraction
4.5.Wound Healing
Completion of Healing
- Lactic acidosis and hypoxia normalization⇒stopping of healing
- Keloids : hypertrophic scars due to local overgrowth of CT
Impaired healing
- inadequate inflammatory response : corticosteroids,immunosuppressants,chemotherapeutic drugs
- Excessive inflammation
- Malnutrition (weight loss,hypoalbuminemia)
5.Healing of Specialized Tissues
Bone
- Inflammation
- Proliferation : specialized granulation tissue (fibrocartilaginous callus)
- osteoclasts
- osteoblasts
- chondroblasts
- Bone remodeling
5.1.Healing of Specialized Tissues
Nerve
- Brain⇒CT scar
- Peripheral nerves⇒sheath&axon regenerates from the nerve cell but reconnects randomly distally
5.2.Healing of Specialized Tissues
Intestine
- 4-7th day : risk of anastomotic leakage
- Strength regained in a week
- Peritoneal adhesions
*
6.Factors Affecting Wound Healing
- Systemic
- Age
- Nutrition
- Smoking
- Metabolic diseases(DM,Metabolic syndrome)
- Drugs: corticosteroids,immunosup,chemo
- CT disorders - Ehler-danlos,marfan syndromes
- Local
- Hypoxia
- Mechanical injury
- Infection
- Edema
- Irradiation
- Ischemia
- Foreign bodies
7.Chronic Wounds &Ulcers
Decubitus ulcers
- prolonged pressure⇒tissue ischemia
- prolonged contact with moisture,urine,feces
- malnutrition
- in immobile,elderly,operated patients
- Treatment:
- drainage of infected space
- excision of necrotic tissue
- musculocutaneous flap
7.1.Chronic Wounds & Ulcers
Venous Ulcers
- poor perfusion and perivascular leakage of plasma
- lower leg
- Treatment: compression stocking,surgical treatment of vein insufficiency
Ischemic Ulcers
- Lateral ankle and foot
- Treatment: revascularisation,hyperbaric oxygen
7.2.Chronic Wounds & Ulcers
Diabetic Ulcers
- Neuropathy⇒trauma
- Microangiopathy⇒ischemia
- Treatment: protection of the ulcer,revascularisation
Treatment of wounds & ulcers
- Control infection w/ antibiotics
- Treat underlying circulatory disease
- Keep wound moist
- Debridement of unhealthy tissue
- Reduce autonomic vasoconstriction
8.Excess Healing
Excess dermal scarring
- Hypertrophic scar if epithelization takes longer than 3-4 wks
- Keloid
- 3 months after surgery
- keloidal fibroblasts synthesize 20x
- treat with local steroid injection
Peritoneal scarring(adhesions)
- Fibrin,fibroblasts &collagen⇒filmy adhesions
- Fibrinolysis w/in a week
- Migration of capillaries,nerves,CT⇒solid adhesions
9.Wound Management
Classification
- I.Clean:
- uninfected,no inflammation
- elective surgical wounds
- e.g.hernia,breast surgery
- management: primary closure
- Infection rate : <2%
- II.Clean-contaminated:
- Minor and brief contamination,minor inflammation
- Clean and sharp with local damage
- e.g.gastric surgery
- management: primary closure and wound cleaning
- infection rate : 1-5%
9.1.Wound Management
Classification
- III.Contaminated:
- Contamination apparent and prolonged,major inflammation
- Ragged and contused wounds w/ gross local damage
- E.g. inflamed appendectomy,penetrating wounds
- management: copious irrigation,debridement and primary closure
- infection rate : 5-25%
- IV.Dirty:
- Gross contamination w/ infection
- Old traumatic wounds >12h
- Severe tissue damage and excessive ischemic tissue
- e.g. abscess,perforated bowel
- management healing by secondary intention
- infection rate : 50%
10.Assessment of Wound Mechanism
- Kinetic energy injury -closed -blunt
- Kinetic energy injury-open-penetrating
- low energy -knife
- high energy - bullet
- Thermal injury
- Heat
- Frost
- Chemical injury
- Electrical injury
11.Surgical Management of Wounds
- Wound evaluation :
- mechanism of injury
- extent of injury and wound type
- decision for wound closure
- Patient consent
- Antimicrobials : tetanus prophylaxis
- Wound prep and sterile field
- Anesthesia
- Debridement-washing
- Hemostasis
- Closure
- Dressing
12.Other skin closure options
- Adhesive tapes
- (+) rapid, simple, no risk of needle injury
- (-) needs dry skin,poor adherence,poor hemostasis,accidental removal
- Skin glue
- (+) rapid,simple,reduced pain,good aethetic result
- (-) poor approximation of deep layers,poor hemostasis
- Surgical skin staples
- (+) fast closure of large wounds,less rxn than sutures
- (-) poor hemostasis
13.Surgical instruments
- Cutting instruments
- Scalpels
- Scissors -for tissues and sutures
- Grasping instruments
- Tissue forceps
- Ratcheted tissue forceps
- Needle-holders
- Retracting instruments
- Hand-held retractors
- Self-retaining retractors
13.1.Surgical instruments
Surgical staplers
- Skin stapler
- Linear stapler
- Gastrointestinal anastomosis stapler
- Circular stapler
13.2.Surgical Instruments
Energy applying instruments
- Diathermy
- Electrocoagulation
- Monopolar- patient return electrode
- Bipolar
Other energy applying instruments
- Mechanical energy (ultrasound scalpel)
- Laser
- Cyrotherapy
- Radiofrequency needles
13.3.Surgical Instruments
Sutures and Needles
- Suture materials
- Absorbable : polyglycolic acid,polydioxanone
- Non absorbable : polypropylene,polyamide
- Suture strand type
- Monofilament
- Multifilament
- Twisted
- Braided
- Suture size : 10/0 - thinner than 1
13.4.Surgical Instruments
Sutures and needles
14.Local Anesthetics
- Inhibit electrical conduction along neurons
- Transient blocking of Na+ transport channels in the cell membrane ⇒ blocks initial depolarization
- sensory neurons are more sensitive than motor neurons
- Lidocaine : 20mg/ml with or w/o adrenaline
- Bupivacaine : 5mg/ml
- Ropivacaine : 7.5 mg/ml
- onset : 5-10 mins, duration 1-6 hrs
14.Local Anesthetic Uses
- Topical
- Lipid soluble cream
- Extent of action :skin and mucosa up to few mm deep
- Local infiltration
- injected into tissue
- local nerves
- Nerve block
- Injected around a nerve or plexus
- Distribution of nerve blocked
- IV block
- IV injection in arterial tourniqueted limb
- Nerve tissue within limb
- Centrineural block
- Epidural or spinal injection
- Multiple dermatomes
- Cavity administration
- intrapleural or intraperitoneal admin
- local nerves in cavity
15.Local Anesthesia Toxicity
- Side effects
- Mouth and tongue numbness
- Anxiety
- Tremor
- Drowsiness
- Tachypnea
- Hypotension
- Nausea & vomiting
- Allergy
16.Local infiltration anesthesia
- Lidocaine
- time to onset : 5-10 min
- dilution : 2% lidocaine - max dose 300 mg for a 70 kg person
- # 23 blue or #25 orange needle
- infiltration technique : inject around site of incision
17.Basic Surgical Skills
- Suturing
- simple interrupted sutures
- running (continuous) sutures
- Knot tying
- Incisions & excisions
- elliptical excision : to take out a lesion
- incision
- Wound debridement
- Hemostasis
- with electrocoagulation
- with ligature
- Dissection
- blunt dissection
- sharp dissection
18.Sterile Technique
- Sterile : all forms of microbial life destroyed
- Aseptic : free from pathogens
- Disinfection: process of destroying all pathogens
- Clean : absence of gross contamination or dirt
Principles
- Reduction of env. contamination
- Disinfection of procedural site
- Isolation of procedural site
- Sterilization of procedural tools
19.Reduction of Environmental Contamination
- Clean OR staff
- clean clothing
- hair and beard covered
- OR shoes
- face mask
- Clean hands
- hand washing (scrub or hydroalcoholic rub)
- Clean air
- closed OR
- laminar airflow
- Clean equipment
- no touching
20.Disinfection of Procedural Site
- Cleaning
- washing to remove macroscoping contamination
- hair removal
- painting skin with antibacterial solution
- chlorohexidine 0.5%, povidone iodine 10%
21.Isolation of Procedural Site
- Gowning and gloving
- sterile gowns
- sterile gloves - sometimes double gloving
- no touch technique
- Draping
- exclusion of operative site w/ sterile towels or shet
- two layers
- raised sterile curtain btw anesthesist & surgeon
22.Sterilization of procedural tools
- Steam:
- Sterilization of all metallic instruments
- Sterilization in packs
- 20 PSI / 126C / 10 min
- Autoclave, flash sterilizes
- Dry heat:
- 160C/ 1h
- Chemical:
- Gas (ethylene oxide)
- Liquid (glutaraldehyde) - 10h soaking
- Plasma (ionized hydrogen peroxide gas)
- Sensitive equipment (endoscopes) : soaked in disinfectant
23.Surgical Team Safety
Body fluids and substances
- Risk of HBV,HCV,HIV
- Avoidance of contact w/ mucosas and skin
- Universal precautions
Sharps and needles
- Risk of injury from scalpels,needles
- Handling,returning & handing over sharp instruments
- Never recap needles
- Never place sharps on pt
- Protect needle point with needle holder
Other hazards
- Radiation exposure
- Electrical shock from equipment
- Toxic substances
24.Patient Safety
Preparation for the procedure
- Patient consent
- Correct patient, correct operation,correct side - mark lesion
- All lab and radiology tests available
- Any pt allergies or important info known
Positioning on operating table
- No metal to skin contact
- No pressure points
- No abnormal traction or angulation of limbs
- Mechanical DVT prophylaxis
- Eyes taped shut to prevent drying
- Stabilization of pt to avoid movement
24.1.Patient Safety
Procedure
- Injury from sharps
- Injury from retractors
- Electrocoagulation,lasers gauzes
- Breach in sterile technique
After procedure
- Risk in transfer from the OR table (tube displacement, injury)
- Post anesthetic observation
25.Systemic Inflammatory Response Syndrome
- Inflammatory response to injury
- Two or more of the criteria:
- T ≥ 38oC or ≤ 36oC
- HR ≥ 90/min
- RR ≥ 20/min
- WBC ≥ 12000/mm3 or ≤4000mm3
- Balance⇒Recovery
- Proinflamatory phase (SIRS)
- Counter - regulatory anti inflammatory response syndrome (CARS)
- Mixed antagonist response syndrome
- Imbalance ⇒ Multi Organ Failure (MOF)
26.Sepsis and Septic shock
- Sepsis : Suspected documented infection + an acute increase of ≥ SOFA points
- Septic shock :
- Sepsis + persisting hypotension that requires vasopressors to maintain MAP of 65mmHg
- Serum lactate level > 2mmol/L (18mg/dL) despite adequate volume resussitation
27.Sequential Organ Failure Assesment Score
28.Acute Phase Proteins
- Non-specific proteins secreted in response to tissue injury
- Produced by liver
- Biomarkers of systemic inflammation
- CRP - normal < 1 mg/dL
- Procalcitonin - normal < 0.15 ng/mL
- IL-6
- CNS inflammatory regulation
Autonomic regulation of:
- HR, BP,RR,GI motility
- Body temp
- Pro-inflammatory vs anti-infammatory response
Afferent Signals
- Inflammatory mediators
- TNFa
- Parasympathetic sensory input
- Cytokines TNFa,IL-1
- Baroreceptors
- Chemoreceptors
- Thermoreceptors
29.1 CNS inflammatory regulation
Cholinergic anti-inflammatory response
- Ach receptors on tissue macrophages : Ach reduces tissue macrophage release of proinflammatory mediators
- Ach reduces macrophage activation
- Effect of PS on HR, Gı motility, arteriole dilation
30.Hormonal Response to Injury
Pathways
- Receptor kinases
- G-protein receptors
- Ligand gated ion channels
ACTH- from anterior pituitary
- glucocorticoid production
Cortisol & Glucocorticoids - adrenal cortex
- Hyperglycemia - release of FFA & TG from fat cells, immunosuppression, down-regulation of pro-inflammatory cytokines
31.Inflammatory Mediators
- Cytokines
- Heat shock proteins (protection from stress)
- Oxygen radicals
- Eicosanoids - endocrine,immune,vasomotor funct.
- FA metabolites : attenuation of inflammatory resp.
- Kallikrein-kinin sys : vasodilation, ↑ capillary permeability
- Serotonin : vasoconstriction,bronchocons.,inotrope
- Histamine : hypotension, ↑capillary permeability
32.Endothelium mediated injury
- ↑ vascular permeability during inflammation
- facilitate O2 delivery
- facilitate immunocyte migration
- ischemia reperfusion injury
- accumulation of neutrophils
- unleashing O2 metabolites,lysosomal enz
- oxidation of basal membranes
- microvascular thromboses
- Endothelium hypoxia,endotoxins,injury and sheer stress produce
- NO -smooth m relaxation
- Prostacyclin - vasodilation & platelet activa.
- Endothelins - most potent vasoconstrictor
- Platelet-activ factor - activates neut,platelets - ↑ vascular permeability
- Atrial Natriuretic Peptides -vasodilation,fluid & electrolyte secretion, aldosterone inhibitors
- Causes of Fluid and electrolyte imbalance
- Surgical trauma - sepsis
- 3rd space fluid isolation
- Peri-operative fasting
- Vomiting
- Diarrhea
34.Body Water
- Total body water = 50-60% of total body weight
- Tissue water concentration
- Muscle-solid organs > fat
- New born>adult>elderly
- Male>female
- Lean>obese
35.Fluid Compartments
- Intracellular fluid : 40% of total body weight
- K+ : 150mM , Na+: 15mM, Mg2+: 40mM, Ca2+: minimal
- Phosphates,sulfates:150mM,HCO3- : 10mM, proteins : 40mM
- Extracellular fluid : 20% of total body weight
- Interstitial fluid 15%
- Plasma 5%
- Na+ : 142mM, K+: 5mM,Ca2+: 5mM,Mg2+:2mM
- Cl-:103mM,HCO3- : 26 mM,Phosphates: 2mM,Sulfates :1mM, Proteins: 17 mM
36.Body Fluid Osmolality
- Total solute concentration : mOsm/kg
- 290-310 mOsm/kg
- water diffuses freely between compartments
37.Fluid Sodium
- Sodium is confined to ECF
- Sodium containing fluids
- expansion of intravascular space - 5%
- 3x expansion of interstitial space - 15%
- Daily solute balance
- Oral intake : 2000 mL
- Cell metabolism : 400 mL
- Urinary excretion: 1500 mL
- Stool: 200 mL
- Skin,Lungs: 600 mL
39.Fluid Volume & Osmolality Control
- Baroreceptors
- Pressure sensors in aortic arch & carotid sinuses
- Osmoreceptors
- Sensors that detect changes in osmolality,kidney
- Hypothalamus⇒vasopressin ⇒renin-angiotensin-aldosterone⇒atrial natriuretic peptide⇒reduction in expanded ECF
40.Body Fluid Disturbances
- Volume disturbances
- Volume deficit
- Volume excess
- Electrolyte concentration disturbances
- Acid-base imbalance
41.Extracellular Volume Deficit
Causes in surgical patients:
- Inability to ingest water
- Loss of GI fluids :
- Nasogastric tube suction
- vomiting
- diarrhea
- enterocutaneous fistula
- Fluid isolation
- soft tissue injuries
- burns
- peritonitis-sepsis
- ileus-obstruction
41.1.Extracellular Volume Deficit
Clinical observations
- Weight loss 1kg/1L
- ↓ skin turgor
- Sunken eyes
- Tachycardia
- Hypotension
- Oliguria
- Confusion
Lab exam:
- ↑BUN,↓GFR
- ↑BUN: Creatine ratio
- ↑Hematocrite
- ↑urine osmolality (higher than serum)
- ↓urine sodium (20mEq/L)
42.Extracellular Volume Excess
Causes:
- Iatrogenic
- Renal dysfunction
- Heart failure
- Cirrhosis
- Inappropriate secretion of antidiuretic hormone
Clinical observations:
- Weight gain
- Peripheral edema- limb swelling
- ↑central venous pressure
- distended jugular veins
- pulmonary edema - fine crackles
- cardiac insufficiency - gallop rhythm
Lab exams:
- ↓ hematocrite
- ↓ urine osmolality
43.Electrolyte Disturbances
Sodium
- Na+ : predominant electrolyte of ECF
- Na+ concentration influences fluid osmolality
- Changes in Na+ are inversely proportional to total body weight
- Serum Na+ : 135-145 mEq/L
Hypernatremia
- causes:
- high volume
- gain of Na+ in excess of water
- hyperaldosteronism,cushing syndrome
- normal or low volume
- loss of free water (renal,GI tract,DI)
- high volume
43.1.Electrolyte Disturbances
Sodium
Clinical Observations of Hypernatremia
- Thirst
- If Na+ concentration > 160mEq/L
- Cellular dehydration - extracellular water shifting
- CNS symptoms - restlessness,irritability,seizures,coma
- Musculoskeletal - weakness
- If hypovolemic hypernatremia
- Tachycardia
- Orthostatic hypotension
Lab exams : serum Na+ > 145 mEq/L severe if > 160, urine specific gravity SG > 1.030 if nonrenal water loss
43.2. Electrolyte Disturbances
Sodium
Hyponatremia
Causes:
- Dilution
- Iatrogenic
- Polydipsia (psychogenic,DM, DI)
- Severe hyperglucemia (glc osmosis)
- Secretion of ADH (post trauma,surgery)
- Drugs (ACEI,antipsychotics)
- Depletion
- Low Na+ diet
- GI losses (vomiting,nasogastric suction)
- Renal losses (diuretics,renal diseases)
43.3.Electrolyte Disturbances
Sodium
Clinical observations of hyponatremia
- If severe - < 120 mEq/L
- CNS - seizures, coma,↑intracranial pressure
- Musculoskeletal - weakness,fatigue,cramps
- Rapid correction of severe hyponatremia⇒ osmotic demyelination syndrome
Lab exams:
- Serum Na+ < 135 mEq/L
- Low urine Na+ concentration < 20 mEq/L if extrarenal losses
- High urine Na+ concentration > 20 mEq/L if renal losses
44.Electrolyte Disturbances
Potassium
- Predominant intracellular cation
- Only 2% of total body K+ is extracellular while 98% is intracellular
- Critical to cardiac and neuromuscular function
- Serum K+ : 3.5-5 mEq/L
Hyperkalemia : K+ > 5mEq/L
Causes:
- Excesive K+ intake - supplements, blood transfuse
- Cell destruction - hemolysis,crush injury
- K+ extracellular shifting - acidosis
- Impaired kidney K+ secretion -K sparing diuretics,renal insufficiency
44.1.Electrolyte Disturbances
Potassium
Clinical Observations of hyperkalemia
- GI - nausea,vomiting,colic
- Neuromuscular - weakness,paralysis
- Cardiovascular - arrythmia,arrest
ECG alterations
- Peaked T waves, flattened P wave
- Prolonged PR interval
- Widened QRS
- V-fib
44.2.Electrolyte Disturbances
Potassium
Hypokalemia : K+ < 3.5 mEq/L
Causes:
- ↓ intake - inadequate oral or iv K+
- Intracellular K+ shifting - alkalosis
- Excessive K+ renal excretion - diuretics,hyperaldosteronism
- GI losses - diarrhea,vomiting,fistula
44.3.Electrolyte Disturbances
Potassium
Clinical observations of hypokalemia
- GI- ileus,constipation
- Neuromuscular-↓reflexes,fatigue,weakness,paralysis
- Cardiovascular-PEA,asystole
ECG alterations
- U waves
- T-wave flattening
- Arrythmias
45.Electrolyte Disturbances
Calcium
- contained in bone matrix 99%
- serum calcium - 50% ionized (free) and 50% bound (protein & phosphate complexes)
- total serum Ca2+ is measured but the ionized is responsible for neuromuscular stability
Hypercalcemia
Causes:
- primary hyperparathyroidism
- malignancy - bone metastases,secretion of PTH related protein
Clinical observations
- GI - nausea,vomiting,abdominal pain
- Neuromuscular - weakness,confusion,coma,pain
- CV- hypertension,arrythmia,ECG alterations
45.1.Electrolyte Disturbances
Calcium
Hypocalcemia : Ca2+< 8.5 mEq/L
Causes:
- Hypoparathyroidism
- Other - pancreatitis,renal failure
Clinical observations:
- In severe hypocalcemia
- Neuromuscular - hypereflexia,tetany,Chvostek’s sign (spasm of facial m. when facial n is tapped at lvl of jaw),Trousseau’s sign (carpal spasm induced by BP cuff), bone pain
- CV - heart failure, ECG alterations
46.Electrolyte Disturbances
Magnesium
- Predominantly intracellular
- 1/3 serum Mg is albumin bound
- Normal serum Mg2+ = 1.5-2.5 mg/dL
Hypermagnesemia
Causes:
- Excess intake - Mg laxatives and antacids
- Renal failure
Clinical observations
- GI - nausea,vomiting
- Neuromuscular- weakness,vomiting, ↓reflexes
- CV-hypotension,arrest,ECG alterations like hyper-K
46.1.Electrolyte Disturbances
Magnesium
Hypomagnesemia : Mg2+ < 1.5 mg/dL
Causes:
- common in hospitalized patients
- poor intake
- ↑ renal excretion - alcohol, diuretics
- GI losses - diarrhea
- acidosis
Clinical observations
- Neuromuscular - hyperactive reflexes,tremors,tetany,seizures
- CV - ECG alterations-torsade de pointes,arrest
- can produce hypocalcemia
- can cause persistent hypokalemia
47.Electrolyte Disturbances
Phosphorus
- primarily a constituent of bone
- predominant intracellular anion HPO43-
- abundant in metabolic active cells : high energy phosphate products (ATP)
- controlled by urinary secretion
- serum phosphorus : 2.5-4.5 mg/dL
Hyperphosphatemia : P-3 > 4.5 mg/dL
Causes
- ↓ urinary excretion
- ↑ intake - phosphorus rich laxatives
- ↑ production- cell destruction
Clinical observations
- asymptomatic
- high calcium-phosphate product⇒calcifications
47.1.Electrolyte Disturbances
Phosphorus
Hypophosphatemia : P-3 < 2.5 mg/dL
Causes:
- poor dietary intake - alcoholism
- antacid administration- binding of P in bowel
- hyperparathyroidism
Clinical observations:
- When severe hypo-p <1 mg/dL
- Neuromuscular - fatigue,weakness,convulsions
- CV- impaired heart contractibility
- Osteomalakia-chronic depletion
48.Acid Base Balance
- Daily metabolism produces 1 mEq/kg of H+
- Produced CO2 is transformed to H2CO3
- Buffering systems
- intracellular proteins- hemoglobin
- extracellular bicarbonate/carbonic acid
H++HCO3- ⇔ H2CO4⇔H2O +CO2
pH = pK + log ( [HCO3- ] / 003 x PCO2
- PCO2 ⇒ regulated by pulmonary ventilation
- HCO3- is regulated by the kidney
- HCO3- reabsorption
- Secretion of H+
- Secretion of NH4+
49.Normal Values
- pH is regulated at 7.35-7.45
- Acidemia ⇒ pH < 7.35
- Alkalemia ⇒ pH > 7.45
- HCO3- : 22-26 mmol/L
- PCO2 : 35-45 mmHg
Anion gap
- UA-UC = [Na+] - ( [HCO3-] +[Cl-]) : 3-11 mEq/L