2Body Fluids Water= most important nutrient for life. Water= primary body fluid. Adult weight is 55-60% water.Loss of 10% body fluid = 8% weight loss SERIOUSLoss of 20% body fluid = 15% weight loss FATALFluid gained each day should = fluid lost each day (2 -3L/day average)What is the minimum output per hour necessary to maintain renal function?30ml/hr
3Functions of Body Fluid Medium for transportNeeded for cellular metabolismSolvent for electrolytes and other constituentsHelps maintain body temperatureHelps digestion and eliminationActs as a lubricant
4Mechanisms of Fluid Gain and Loss Fluid intake 1500mlFood intake 1000mlOxidation of nutrients ml (10ml of H20 per 100 Kcal)Loss“Sensible” Can be seen. Urine ml Sweat ml“Insensible” Not visible. Skin (evaporation) 500ml Lungs ml Feces ml
5Regulation of FluidsHypothalmus –thirst receptors (osmoreceptors) continuosly monitor serum osmolarity (concentration). If it rises, thirst mechanism is triggered. +Vasopressin (AKA ADH )– increasing H20 reabsorptionPituitary regulation- posterior pituitary releases ADH (antidiuretic hormone) in response to increasing serum osmolarity. Causes renal tubules to retain H20.Thirst is a late sign of water deficitWhat controls or regulates the fluids in our body?Thirst –simplest way to maintain fluid balanceThirst center failure- onconscious or confused pt. To not respondWhich age group is most prone to dehydration because their body’s weight is mostly water?
6Regulation of Fluids (continued ) Renal regulation- Nephron receptors sense decreased pressure (low osmolarity) and kidney secretes RENIN. Renin – Angiotensin I – Angiotensin IIAngiotensin II causes Na and H20 retention by kidneys AND…..Stimulates Adrenal Cortex to secrete Aldosterone which causes kidneys to excrete K and retain Na and H20.What also is increased here?
7Consider This….The Geriatric Client -normal physiological aging results in decreased thirst mechanism decreased # of sweat glands decreased renal function -there also may be decreased mobility and/or cognitive function which impacts their ability to get adequate fluid intake.
8Variations in Body Fluids Elderly: Have lower % of total body fluid than younger adultsWomen: Have lower % total body fluid than menWHY DO YOU THINK THIS IS ?????Increased risk for fluid/electrolyte imbalance with decreased muscle since muscle cells hold more waterMuscle tissue has more H20 content THAN adipose tissue
9Intracellular fluid (ICF) Fluid CompartmentsExtracellular Fluid (ECF)Fluid outside the cell.1/3 of body’s H20More prone to loss3 types:Interstitial- fluid around/between cellsIntravascular- (plasma) fluid in blood vesselsTranscellular –CSF, Synovial fluid etcIntracellular fluid (ICF)Fluid inside the cellMost (2/3) of the body’s H20 is in the ICF.NOTE: Potter & Perry speaks to the “percentage of body weight” % of BODY WEIGHT = ICF fluid % of BODY WEIGHT = ECF fluidTranscellular fluid is a negligible amount
10Consider this….Age variations exist in regards to H20 content of fluid compartmentsInfants = 60% of H20 is found in ECF 40% of H20 is found in ICFWhat might this mean in regards to fluid loss for an infant?This is reverse of adults THEREFORE the infant is more susceptible to fluid lossReverse of adults!Infant MORE PRONE to fluid LOSS!
11Fluid Balance Dynamic process Balance between body fluids and electrolytesAttraction between ions (electrolytes) and water (fluids) causes fluids to move across membranes and leave their compartments.SEE NEXT SLIDES FOR IN-DEPTH
12Solvent (H20) MovementCell membranes are semipermeable allowing water to pass throughOsmosis- major way fluids transported Water shifts from low solute concentration to high solute concentration to reach homeostasis (balance).Water is a solventConcentration of particles in solution (pulling action = osmolarity)Isotonic have almost same osmolarity as plasma therefore there is no pull
13Osmolarity Concentration of particles in solution The greater the concentration (Osmolarity) of a solution, the greater the pulling force (Osmotic pressure)Normal serum (blood) osmolarity = mOSM/kgA solution that has HIGH osmolarity is one that is > serum osmolarity = HYPERTONIC solutionA solution that has LOW osmolarity is one that is < serum osmolarity = HYPOTONIC solutionA solution that has equal osmolarity as serum = ISOTONIC solutionOsmosis, by the way, is the reason that drinking salt water will kill you.The HIGH osmolarity salt water in the GI system rapidly pulls water into the GI system and excretion – rapidly dehydrating cellsSEE NEXT SLIDES FOR FURTHER DISCUSSION
14Hypertonic FluidsHypertonic fluids have a higher concentration of particles (high osmolality) than ICFThis higher osmotic pressure shifts fluid from the cells into the ECFTherefore Cells placed in a hypertonic solution will shrink
15Hypertonic Fluids Used to temporarily treat hypovolemia Used to expand vascular volumeFosters normal BP and good urinary output (often used post operatively)Monitor for hypervolemia ! Not used for renal or cardiac disease. THINK – Why not?D5% 0.45% NSD5% NSD5% LRUsed for post op, decreases intracellular edema, fosters normal BP and good urinary output.D51/2NS, D5NS, D5RLHyperalPulmonary Edema
16Hypotonic FluidsHypotonic fluids have less concentration of particles (low osmolality) than ICFThis low osmotic pressure shifts fluid from ECF into cellsCells placed in a hypotonic solution will swellECF- extracellular fluids
17Hypotonic Fluids Used to “dilute” plasma particularly in hypernatremia Treats cellular dehydrationDo not use for pts with increased ICP risk or third spacing risk0.45%NS0.33%NS
18Isotonic FluidIsotonic fluids have the same concentration of particles (osmolality) as ICF ( mOsm/L)Osmotic pressure is therefore the same inside & outside the cellsCells neither shrink nor swell in an isotonic solution, they stay the sameICF intracellular fluid - fluid inside the cellD5W isotonic /Normal saline solution is isotonic because it has almost the same concentration of sodium as blood.Used to replace Ecvlume
19Isotonic Fluid Expands both intracellular and extracellular volume Used commonly for: excessive vomiting,diarrhea0.9% Normal salineD5WRinger’s Lactate
20Other Osmotic Factors ALBUMIN ( a serum protein ) Albumin in the serum has osmotic properties called colloid pressureAlbumin pulls H20 from the interstitial compartments into the intravascular compartments (serum). Helps to maintain BP.Persons with low serum albumin levels tend to retain fluid in their interstitial layers. What abnormal assessments might you find in the client with low serum albumin levels?Edema, hypotension
21Hmmm…….What type of IV fluid (hypotonic – isotonic – hypertonic) might be of benefit to this client with low albumin levels?Hypertonic
22Consider this….When tissue injury occurs, proteins pathologically leak from the intravascular space into the intersititial space. Termed: Third spacingThis explains __________ as a sign of the inflammatory process.EDEMAEDEMA
23Solute Movement - Diffusion Movement of solutes from high concentration to low concentrationIt is a PASSIVE movement DOWN the concentration gradiant. (requires no energy)Many body processes use diffusion. Example: O2 and CO2 exchangeRate is affected by: concentration gradiant, permeability-surface area-thickness of membranes, and size of particles. (Fick’s Law)Filtration- from pressure to low pressure
24Solute Movement –other mechanisms Active transport- requires energy (ATP) to move from low concentration to high concentration (uphill) Example: Na / K pumpMay be enhanced by carrier molecules with binding sites on cell membrane Example: Glucose (Insulin promotes the insertion of binding sites for Glucose on cell membranes).
25Filtration Solvent AND solute movement Passage from an area of High Pressure to an area of Low Pressure Termed: Hydrostatic PressureExample: Arterioles have higher pressure than ICF Fluid, oxygen and nutrients move into cells Venules have lower pressure than ICF Fluid, carbon dioxide and wastes move out of cells
26Fluid volume deficit FVD (Hypovolemia) Loss of both H20 and electrolytes from ECF.Causes include: Increased output, Hemorrhage, vomiting, diarrhea, burns, ORFluid shift out of vascular space ( “third spacing” ) into interstitial spacesDehydration: Fluid intake is not sufficient to meet the body’s needs.Dehydration- if water isn’t adequately replaced dehydration resultsDx TestsElevated HCTElevated NASp. Gravity above 1.030Monitor lab workCause- unless unconsciousSudden wt. change is a major indicator of fluid loss
27DehydrationIsotonic dehydration = H20 & electrolyte loss in equal amounts; diarrhea and vomitingHypertonic dehydration = H20 loss greater than electrolyte loss; excessive perspiration, diabetes insipidus
28Assessment FVD - Hypovolemia Cardiovascular:Diminished peripheral pulses; quality 1+(thready)Decreased BP & orthostatic hypotensionIncreased HRFlat neck & hand veins in dependent positionElevated Hematocrit (Hct)Gastrointestinal:ThirstDecreased motility; diminished bowel sounds, possible constipation
30Nursing Diagnosis - FVD Deficient Fluid Volume R/T loss of GI Fluids via vomiting AEB elevated Hct, dry mucous membranes, decreased output, thirst
31Planning - FVDClient will demonstrate fluid balance aeb moist mucous membranes, balanced I & O measurements, Hct WNL, by ….
32Interventions for FVD - Hypovolemia Prevent further fluid lossOral rehydration therapyIV therapyMedications; antiemetics, antidiarrhealsMonitor CV, Resp, Renal, GI statusMonitor electrolytes – possible supplement rxMONITOR WEIGHT and I & OOral- keep fluids at bedside, offer frequentlyIV fluids, blood & other parenteral measures Hyperal etc.Meds- depending on the causeDiarrhea give anti diarrhea medsVomiting give anti emeticsVasopressors if pt. In shock cause vasoconstriction and increase BP
33NCLEX Practice Intravenous fluids are ordered for your client who is experiencing diarrhea and vomiting forthe past 2 days. Which IV solution would thenurse expect to see prescribed?D5NS0.45%NSD51/2NSRLRingers Lactate = ISOTONIC for replacement of ISOTONIC DEHYDRATION (loss of fluid & Electrolyte)
34Fluid Volume Excess FVE - Hypervolemia Fluid overload is an excess of body fluid - overhydrationExcess fluid volume in the intravascular area-hypervolemiaExcess fluid volume in interstitial spaces edemaIncrease in vascular bloodThird spacing could be in the abd- ascitespleural effusion in the lungs
35Fluid Volume Excess Causes: Increased Na/H2O retention Excessive intake of Na (PO or IV)Excessive intake of H2O ( PO or IV) (Water intoxication)Syndrome of inappropriate antidiuretic hormone (SIADH)Renal failure, congestive heart failureRetention-Intake- Poorly controlled IV therapy/ rapid hypertonic solution/ excessive sodium bicarb / excessive Na intake
38Planning - FVEClient will demonstrate fluid balance by balanced I & O measurements, Serum Na WNL, etc. by ….
39Interventions FVE - Hypervolemia Restore normal fluid balance, prevent further overloadDrug therapy; diureticsDiet therapy; decrease Na & fluidsMonitor intake and output (I & O)Monitor weightsMonitor electrolytesMonitor CV, Resp, Renal systemsDrug therapy- - diuretics for overhydration increases excretion of water and sodiumDiet-- restricting fluid and sodium intakeMonitor lab work
40Clinical ApplicationYou have been assigned to care for an 80y.o. client admitted with hypernatremia that has an IV infusing 0.45% 100ml/hr via pump and an indwelling urinary catheter. At 11am you assess an output in the urinary drainage bag of 150ml dk amber urine. You also notice that the client is SOB while speaking on the phone to her daughter.What do you think is happening??What will you do??
41Want more Information??? CHECK OUT THE SUMMARYWant more Information??? CHECK OUT THEWEBLINKSFor Chapter 41 on EVOLVE
42Electrolytes Work with fluids to keep the body healthy and in balance They are solutes that are found in various concentrations and measured in terms of milliequivalent (mEq) unitsCan be negatively charged (anions) or positively charged (cations)For homeostasis body needs: Total body ANIONS = Total body CATIONS1 mEq MILLIEQUIVALENT = 1 MG OF HYDROGEN
43Electrolytes Cations Positively charged Sodium Na+ Potassium K+ Calcium Ca++Magnesium Mg++AnionsNegatively chargedChloride Cl-Phosphate PO4-Bicarbonate HCO3-Each will be discussed except Bicarbonate as that plays a role in acid base balance which will be covered in NR33
45Sodium Na+ 135-145mEq/L Major Cation Chief electrolyte of the ECF Regulates volume of body fluidsNeeded for nerve impulse & muscle fiber transmission (Na/K pump)Regulated by kidneys/ hormonesNa concentrations effected by water intake and salt untakeHormones -Aldsterone
46Hmmm…Hyper and Hypo Natremia are the mostcommon electrolyte disturbances. Why doyou think that is?It is most abundant in the EXTRACELLULAR FLUID and therefore more prone to fluctuation.
47Hyponatremia Serum Na+ <135mEq/L Results from excess of water or loss of Na+Water shifts from ECF into cellsS/S: abd cramps, confusion, N/V, H/A, pitting edema over sternumTx: Diet/IV therapy/fluid restrictionsCausesPoor IV therapy- IV therapy increased water in blood Na is dilutedCHFRenal FailureGI: vomiting diarrhea drainageSkin: sweating burnsdiuretic drugsTXDiet- foods high in sodium- IV solutions ordered if hypovolemia (low volume)Fluid excess- osmotic diuretics ordered to promote excretion of water rather than sodium (mannitol)Fluid restriction till Na returns to normLop diueretics to to remove excess fluidAssess: VS skin integrity, seizures, I & O/ monitor lytes
48Lets think about … Hyponatremia What are some medical conditions that may cause a dilutional hyponatremia? CHF Renal Failure SIADH ( Cancer, pituitary trauma ) Addisons Disease ( hypoaldosteronism & Na loss )What are some conditions that might cause actual loss of sodium from the body? GI losses – nasogastric suctioning, vomiting, diarrhea Certain diuretic therapiesPermanent neurological damage can occur when serum Na levels fall below 110 mEq/L. Why? Hypotonic environment swells cells, increasing ICP – brain damage
49Hypernatremia Serum Na+> 145mEq/L Results from Na+ gained in excess of H2O OR Water is lost in excess of Na+Water shifts from cells to ECFS/S: thirst, dry mucous membranes & lips, oliguria, increased temp & pulse,flushed skin,confusionTx: IV therapy/dietCauses- increased Na intake- rapid infusion of saline solution/po intakeloss of water – diarrhea/DM/decreased water intake/ impaired thirst center/can’t swallowFluid shift from ICF to ECF ….(Na pulls h2o out of cells, kidneys excrete Na and water follows)Tx-if caused by fluid loss Need slow gradual return to normal Na+ by IV hypotonic solution 0.45%NSPt. Teaching avoid high Na foods, canned soups, processed foods, ketchup AVOID antacids high in sodium bicarbI&O, review diet, meds,Moniotr weight, note change LOC
50Let’s think about…. Hypernatremia What are some medical conditions that may cause elevated serum Na? Renal failure Diabetes Insipidus Diabetes Mellitus ( hyperglycemic dehydration) Cushings syndrome (hyperaldosteronism)What are some other patient populations at risk for hypernatremia? Elderly ( decreased thirst mechanism ) Patient’s receiving: -tube feedings -corticosteroid drugs -certain diuretic therapiesSeizures, coma, death my result if hypernatremia is left untreated. Why? Cells loose fluid into the ECF causing irreversible cell damage.
51Critical Thinking Hypo / Hyper Natremia For the client experiencingFVE & hyponatremia d/texcessive intake of water,which IV solution would youexpect the physician toorder?D5NSNSD5W½ NSFor the client experiencingFVD and hypernatremiad/t excessive water loss,which IV solution wouldyou expect the physicianto order?D5 ½ NSD5RLD5W½ NS
52Potassium K+ 3.5-5.0 mEq/L Chief electrolyte of ICF Major mineral in all cellular fluidsAids in muscle contraction, nerve & electrical impulse conduction, regulates enzyme activity, regulates IC H20 content, assists in acid-base balanceRegulated by kidneys/ hormonesInversely proportional to Na
53Hypokalemia Serum level < 3.5mEq/L Results from decreased intake, loss via GI/Renal & potassium depleting diureticsLife threatening-all body systems affectedS/S muscle weakness & leg cramps, decreased GI motility, cardiac arrhythmiasTx: diet/supplements/IV therapyEffects skeletal/cardiac/smooth muscleCauses:Inadequate intakeAlcoholism/DiureticsExcessive Vomiting & diarrheaTxID causeHigh K diet, …oranges, broccoli, meat protein foods,banana, apricotsPO supplements commonIV therapy always diluted…
54Lets think about … Hypokalemia What are some medical conditions that may cause a hypokalemia? Renal Disease / CHF (dilutional) Metabolic AlkalosisCushings Disease ( Na retention leads to K loss )What are some conditions that might cause actual loss of potassium from the body? GI losses – nasogastric suctioning, vomiting, diarrhea Certain diuretic therapies Inadequate intake – ( body cannot conserve K, need PO intake)Cardiac arrest may occur when serum K levels fall below 2.5 mEq/L. Why? Increased cardiac muscle irritability leads to PACs and PVCs, then AF
55Hyperkalemia Serum level >5 mEq/L Results from excessive intake, trauma, crush injuries, burns, renal failureS/S muscle weakness, cardiac changes, N/V, parathesias of face/fingers/tongueTx:diet/meds/IV therapy/ possible dialysis…(false rise due to tight tourniquet or hemolized specimen) occursPoor elimination by kidneysParathesia -tinglingTx-Depends on causeHold Kmeds, low K diet orderdKayexalate administered to increase excretion of KIV therapy add volume to dilute K+Monitor for fluid overload.
56Lets think about … Hyperkalemia What are some medical conditions that may cause hyperkalemia? Renal Disease=most common cause Burns and other major tissue trauma Metabolic AcidosisAddison’s Disease ( Na loss leads to K retention )What are some conditions that might cause potassium levels to rise in the body? Certain diuretic therapies Excessive intake – ( inappropriate supplements)Cardiac arrest may occur when serum K levels rise above mEq/L. Why? Decreased electrical impulse conduction leads to bradycardia and eventual asystole.
57Critical Thinking Potassium IV additives Which of the following interventions will thenurse undertake when administeringparenteral K additives?Monitor the IV site for phlebitisPlace on cardiac monitor if > 10 mEqAssure of adequate mixing of K in solutionMonitor for elevated K levelsMonitor for decreased Na levelsAdminister potassium by slow IV push methodNEVER!!!
58Calcium Ca++mEq/LMost abundant in body but: 99% in teeth and bonesNeeded for nerve transmission, vitamin B12 absorption, muscle contraction & blood clottingInverse relationship with PhosphorusVitamin D needed for Ca absorptionmg/deciliter dLVit D needed for Ca absorption
59Hypocalcemia Serum Ca < 4.3mEq/L Results from low intake, loop diuretics, parathyroid disorders, renal failureS/S osteomalacia, EKG changes, numbness/tingling in fingers, muscle cramps / tetany, seizures, Chovstek Sign & Trousseau SignTx: diet/IV therapyCommon after thyroid surgeryChovstek sign-Tap facial nerve in front of ear= facial spasmTrousseau- carpal spasm after BP cuff inflated due to increased neuromuscular excitabilityTX -Ca supplements…dietary. Dairy green veg, sardines salmonIf severe-IV calcium gluconate
61Lets think about … Hypocalcemia What are some medical conditions that may cause hypocalcemia? Hypoparathyroidism (low PTH levels = decreased release of Ca from bones) S/P thryoid surgery ( low Calcitonin = decreased release of Ca from bones) Acute pancreatitis Crohns Disease Hyperphosphatemia ( ESRF)What are some other conditions that might cause low Ca?GI losses – nasogastric suctioning, vomiting, diarrhea Long term immobilization Lactose intoleranceIf hypocalcemia is prolonged, the body will utilize stored Ca from bones. What complication might arise? Fractures ( late sign )
62Hypercalcemia Serum Ca > 5.3mEq/L Results from hyperparathyroidism, some cancers, prolonged immobilizationS/S muscle weakness, renal calculi, fatigue, altered LOC, decreased GI motility, cardiac changesTx: medication/ IV therapyRemember it’s in the blood not the bonesCauses-high intakeTX-Depends on cause encourage mobility,immobilization causes demineralization of bones leading to fractures remove parathyroid tumorsencourage fluids to prevent renal calculiLower Ca by IV therapy causes diuresis encouraging kidney excretionCalcium binding meds given to promote excretion of calcium.
63Lets think about … Hypercalcemia What are some medical conditions that may cause hypercalcemia? Hyperparathyroidism (high PTH levels = increased release of Ca from bones) Paget’s Disease Some Cancers – Multiple Myleoma Chronic Alcoholism ( with low serum phosphorus )What are some other conditions that might cause low Ca?Excessive intake of Ca OR Vitamin D Excessive intake of OTC antacidsIf hypercalcemia is uncorrected, AV block and cardiac arrest may occur.
64Magnesium Mg2+ 1.5-2.5mEq/L Most located within ICF Needed for activating enzymes, electrical activity, metabolism of carbs/proteins, DNA synthesisRegulated by intestinal absorption and kidney
65Hypomagnesemia Serum < 1.5mEq/L Results from decreased intake, prolonged NPO status, chronic alcoholism & nasogastric suctioningS/S: muscle weakness, cardiac changes, mental changes, hyperactive reflexes & other hypocalcemia S/S.Tx: replacement IV therapy restore normal Ca levels ( Mg mimics Ca) seizure precautions
66Hypomagnesemia Common in critically ill patients Associated with high mortality ratesIncreases cardiac irritability and ventricular dysrhythmias - especially in patients with recent MIMaintenance of adequate serum Mg has been shown to reduce mortality rates post MI
67Hypermagnesemia Serum>2.5mEq/L Results from renal failure, increased intakeS/S: flushing, lethargy, cardiac changes (decreased HR),decreased resp, loss of deep tendon reflexesTx: restrict intake diuretic rxFlushing due to peripheral vasodilationResp. deep shallow and slow
68Chloride Cl- 95-105mEq/L Most abundant anion in ECF Combines with Na to form saltsMaintains water balance, acid-base balance, aids in digestion (hydrochoric acid) & osmotic pressure (with Na and H20)Regulated by kidneysFollows Sodium (Na)
69Hypochloremia Serum level 96mEq/L Results from prolonged vomiting & suctioningS/S metabolic alkalosis, nerve excitability, muscle cramps, twitching, hypoventilation, decreased BP if severeTx: diet/IV therapyTx:correct cause, diet increase Cl, vomiting reduce it, replacement thru IV therapy… can br given orally ie. Salty broth
70Hyperchloremia Serum level > 106mEq/L Results from excessive intake or retention by kidneys – metabolic acidosisS/S Arrhythmias, decreased cardiac output, muscle weakness, LOC changes, Kussmauls’s respirationsTx: restore fluid & electrolyte balanceTx- treat underlying cause, VS, reorient if confusedKussmals –rapid and deep without pauses above 20/min
71Phosphate PO4-mg/dlNeeded for acid-base balance,neurological & muscle function, energy transfer ATP & affects metabolism of carbs/proteins/lipids, B vitamin synthesisFound in the bonesRegulated by intake and kidneysInversely proportional to Calcium Therefore some regulation by PTH as well
72Hypophosphatemia Serum level < 1.8mEq/L Results from decreased intestinal absorption and increased excretionS/S bone & muscle pain, mental changes, chest pain, resp. failureTx: Diet/ IV therapyTx- vs,assess resp, neuro statusIV meds safety
73Hyperphosphatemia Serum level> 2.6mEq/L Results from renal failure, low intake of calciumS/S: neuromuscular changes (tetany), EKG changes, parathesia-fingertips/mouthTx: Diet; hypocalcemic interventions Medications: phosphate bindingThe body can tolerate hyperphosphatemia fairly well BUT the accompanying hypocalcemia is a larger problem!Tx: Correct the under lying cause..renal failure, diet, decreased absorption, Iv fluids, vsDiet limit foods
74Critical Thinking - NCLEX The nurse is caring for a client with renal failure whose magnesium level is 3.6 mg/dL. Which of the following signs would the nurse most likely expect to note in the client based on this Mg level?TwitchingHyperactive reflexesIrritabilityLoss of deep tendon reflexes
75Electrolyte homeostasis This means to maintain balance… to control by balancing the dietary intake of electrolytes with the renal excretion and reabsorption of electrolytes
76Interventions for F/E balance Assess patient carefully- note changesMonitor I & O (Intake & Output)Monitor weight changesMonitor urineMonitor vsMonitor lab results and dx testMaintain proper IV therapyNote changes- significant factor
77Summary Fluid compartments in the body must balance Body systems regulate F&E balanceAssessment of body fluid is important to determine causes of imbalanceInterventions for imbalances are based on the cause