2.FLUID AND ELECTROLYTE MANAGEMENT OF SURGICAL PATIENT
26. Whi h the ll wing are NO hara teristi ndings a ute renal ailure? A. BUN >100 mg/dL B. Hyp kalemia C. Severe a id sis D. Uremi peri arditis E. Uremi en ephal pathy
Answer: A Hyperkalemia, severe a id sis, uremi en ephal pathy, and uremi peri arditis are all indi ati ns li e-threatening pr blems, and urgent rre ti n is mandat ry. Elevati n BUN is mm nly seen as well, but is n t itsel an indi ati n r dialysis. (See S hwartz 10th ed., p. 81.)
1. Tree days afer surgery r gastri ar in ma, a 50-year ld al h li male exhibits delirium, mus le trem rs, and hypera tive tend n re exes. Magnesium de ien y is suspe ted. All the ll wing statements regarding this situati n are true EXCEP A. A de isi n t administer magnesium sh uld be based n the serum magnesium level. B. Adequate ellular repla ement magnesium will require 1 t 3 weeks. C. A n mitant al ium de ien y sh uld be suspe ted. D. Cal ium is a spe i antag nist the my ardial e e ts magnesium.
Answer: A Magnesium de i ien y sh uld be suspe ted in any maln urished patient wh exhibits disturbed neur mus ular r erebral a tivity in the p st perative peri d. Lab rat ry n irmati n ten is n t reliable, and the syndr me may exist in the presen e a n rmal serum magnesium level. Hyp al emia ten exists, parti ularly in patients wh have lini al signs tetany. Intraven us magnesium an be administered sa ely t a well-hydrated patient r initial treatment a severe de i it, but n mitant ele tr ardi graphi m nit ring is essential. he ele tr ardi graphi hanges ass iated with a ute hypermagnesemia resemble th se hyperkalemia, and al ium hl ride r glu nate sh uld be readily available t untera t any adverse my ardial e e ts ex ess magnesium i ns. Partial r mplete relie sympt ms may ll w the initial in usi n magnesium, alth ugh ntinued repla ement r a peri d 1 t 3 weeks is ne essary t replenish ellular st res. (See S hwartz 10th ed., p. 78.)
. Hyp al emia may ause whi h the ll wing? A. C ngestive heart ailure B. Atrial brillati n C. Pan reatitis D. Hyp parathyr idism
Answer: A Mild hyp al emia an present with mus le ramping r digital/peri ral paresthesias. Severe hyp al emia leads t de reased ardia ntra tility and heart ailure. ECG hanges hyp al emia in lude pr l nged Q interval, -wave inversi n, heart bl k, and ventri ular ibrillati n. Hyp parathyr idism and severe pan reatitis are p tential auses hyp al emia. (See S hwartz 10th ed., p. 72.)
29. Te rst step in the management a ute hyper al emia sh uld be A. C rre ti n de it extra ellular uid v lume B. Hem dialysis. C. Administrati n ur semide. D. Administrati n mithramy
Answer: A Patients with a ute hyper al emia usually have either a ute hyperparathyr idism r metastati breast ar in ma with multiple b ny metastases. hese patients devel p severe heada hes, b ne pain, thirst, emesis, and p lyuria. Unless treatment is instituted pr mptly, the sympt ms may be rapidly atal. Immediate rre ti n the ass iated de i it extra ellular luid v lume is the m st imp rtant step in treatment. When e e tive, this results in the l wering the serum al ium level by diluti n. On e extra ellular luid v lume has been repla ed, ur semide is e e tive treatment. Hem dialysis may als be empl yed, but its e e t is less rapid. Mithramy in is very use ul in ntr lling metastati b ne disease, but its e e t is sl w, and it ann t be depended up n when the patient has a ute hyper al emia. (See S hwartz 10th ed., p. 72.)
3. Whi h the ll wing is an early sign hyperkalemia? A. Peaked waves B. Peaked P waves C. Peaked (sh rtened) QRS mplex D. Peaked U waves
Answer: A Sympt ms hyperkalemia are primarily GI, neur mus ular, and ardi vas ular. GI sympt ms in lude nausea, v miting, intestinal li , and diarrhea; neur mus ular sympt ms range r m weakness t as ending paralysis t respirat ry ailure; while ardi vas ular mani estati ns range r m ele tr ardi gram (ECG) hanges t ardia arrhythmias and arrest. ECG hanges that may be seen with hyperkalemia in lude Peaked waves (early hange) Flattened P wave Pr l nged PR interval ( irst-degree bl k) Widened QRS mplex Sine wave rmati n Ventri ular ibrillati n (See S hwartz 10th ed., p. 71.)
What is the best determinant whether a patient has a metab li a id sis versus alkal sis? A. Arterial pH B. Serum bi arb nate C. Pco2 D. Serum CO2 level
Answer: A While bi arb nate, Pco2 , and patient hist ry ten an suggest the m st likely metab li derangement, nly the measurement arterial pH n irms a id sis versus alkal sis. (See S hwartz 10th ed., p. 74.)
Cal ulate the daily maintenan e uids needed r a 60-kg emale A. 2060 B. 2100 C. 2160 D. 2400
Answer: B A 60-kg emale w uld re eive a t tal 2100 mL luid daily: 1000 mL r the irst 10 kg b dy weight (10 kg × 100 mL/kg/ day), 500 mL r the next 20 kg (10 kg × 50 mL/kg/day), and 80 mL r the last 40 kg (40 kg × 20 mL/kg/day). (See S hwartz 10th ed., p. 78.)
A patient wh has spasms in the hand when a bl d pressure u is bl wn up m st likely has A. Hyper al emia B. Hyp al emia C. Hypermagnesemia D. Hyp magnesemia
Answer: B Asympt mati hyp al emia may ur with hyp pr teinemia (n rmal i nized al ium), but sympt ms an devel p with alkal sis (de reased i nized al ium). In general, sympt ms d n t ur until the i nized ra ti n alls bel w 2.5 mg/dL, and are neur mus ular and ardia in rigin, in luding paresthesias the a e and extremities, mus le ramps, arp pedal spasm, strid r, tetany, and seizures. Patients will dem nstrate hyperre lexia and p sitive Chv stek sign (spasm resulting r m tapping ver the a ial nerve) and r usseau sign (spasm resulting r m pressure applied t the nerves and vessels the upper extremity, as when btaining a bl d pressure). De reased ardia ntra tility and heart ailure an als a mpany hyp al emia. (See S hwartz 10th ed., p. 72.)
20. Te metab li derangement m st mm nly seen in patients with pr use v miting A. Hyp hl remi , hyp kalemi metab li alkal sis B. Hyp hl remi , hyp kalemi metab li a id sis C. Hyp hl remi , hyperkalemi metab li alkal sis D. Hyp hl remi , hyperkalemi metab li a id s
Answer: B Hyp hl remi , hyp kalemi metab li alkal sis an ur r m is lated l ss gastri ntents in in ants with pyl ri sten sis r in adults with du denal ul er disease. Unlike v miting ass iated with an pen pyl rus, whi h inv lves a l ss gastri as well as pan reati , biliary, and intestinal se reti ns, v miting with an bstru ted pyl rus results nly in the l ss gastri luid, whi h is high in hl ride and hydr gen, and there re results in a hyp hl remi alkal sis. Initially the urinary bi arb nate level is high in mpensati n r the alkal sis. Hydr gen i n reabs rpti n als ensues, with an a mpanied p tassium i n ex reti n. In resp nse t the ass iated v lume de i it, ald ster ne-mediated s dium reabs rpti n in reases p tassium ex reti n. he resulting hyp kalemia leads t the ex reti n hydr gen i ns in the a e alkal sis, a parad xi a iduria. reatment in ludes repla ement the v lume de i it with is t ni saline and then p tassium repla ement n e adequate urine utput is a hieved. (See S hwartz 10th ed., p. 74.)
6. Whi h the ll wing is FALSE regarding hypert ni saline? A. Is an arteri lar vas dilat r and may in rease bleeding B. Sh uld be av ided in l sed head injury C. Sh uld n t be used r initial resus itati n D. In reases erebral per usi n
Answer: B Hypert ni saline (7.5%) has been used as a treatment m dality in patients with l sed head injuries. It has been sh wn t in rease erebral per usi n and de rease intra ranial pressure, thus de reasing brain edema. H wever, there als have been n erns in reased bleeding be ause hypert ni saline is an arteri lar vas dilat r. (See S hwartz 10th ed., p. 76.)
When la ti a id is pr du ed in resp nse t injury, the b dy minimizes pH hange by A. De reasing pr du ti n s dium bi arb nate in tissues B. Ex reting arb n di xide thr ugh the lungs C. Ex reting la ti a id thr ugh the kidneys D. Metab lizing the la ti a id in the liver
Answer: B La ti a id rea ts with base bi arb nate t pr du e arb ni a id. he arb ni a id is br ken d wn int water and arb n di xide that is ex reted by the lungs. Any diminuti n in pulm nary un ti n je pardizes this rea ti n. (See S hwartz 10th ed., p. 73.)
An al h li patient with serum albumin 3.9, K 3.1, Mg 2.4, Ca 7.8, and PO4 3.2 re eives three b luses IV p tassium and has serum p tassium 3.3. Y u sh uld A. C ntinue t b lus p tassium until the serum level is >3.6. B. Give MgSO4 IV. C. Che k the i nized al ium. D. Che k the BUN and reatinine.
Answer: B Magnesium depleti n is a mm n pr blem in h spitalized patients, parti ularly in the ICU. he kidney is primarily resp nsible r magnesium h me stasis thr ugh regulati n by al ium/magnesium re ept rs n renal tubular ells that sense serum magnesium levels. Hyp magnesemia results r m a variety eti l gies ranging r m p r intake (starvati n, al h lism, pr l nged use IV luids, and t tal parenteral nutriti n with inadequate supplementati n magnesium), in reased renal ex reti n (al h l, m st diureti s, and amph teri in B), GI l sses (diarrhea), malabs rpti n, a ute pan reatitis, diabeti ket a id sis, and primary ald ster nism. Hyp magnesemia is imp rtant n t nly r its dire t e e ts n the nerv us system but als be ause it an pr du e hyp al emia and lead t persistent hyp kalemia. When hyp kalemia r hyp al emia exist with hyp magnesemia, magnesium sh uld be aggressively repla ed t assist in rest ring p tassium r al ium h me stasis. (See S hwartz 10th ed., p. 73.)
28. Ex essive administrati n n rmal saline r uid resus itati n an lead t what metab li derangement? A. Metab li alkal sis B. Metab li a id sis C. Respirat ry alkal sis D. Respirat ry a id sis
Answer: B S dium hl ride is mildly hypert ni , ntaining 154 mEq s dium that is balan ed by 154 mEq hl ride. he high hl ride n entrati n imp ses a signi i ant hl ride l ad n the kidneys and may lead t a hyper hl remi metab li a id sis. S dium hl ride is an ideal s luti n, h wever, r rre ting v lume de i its ass iated with hyp natremia, hyp hl remia, and metab li alkal sis. (See S hwartz 10th ed., p. 74.)
32. Re eeding syndr me an be ass iated with all the ll wing EXCEP A. Respirat ry ailure B. Hyperkalemia C. C n usi n D. Cardia arrhythmias
Answer: B With re eeding, a shi t in metab lism r m at t arb hydrate substrate stimulates insulin release, whi h results in the ellular uptake ele tr lytes, parti ularly ph sphate, magnesium, p tassium, and al ium. H wever, severe hypergly emia may result r m blunted basal insulin se reti n. (See S hwartz 10th ed., p. 81.)
8. Fluid resus itati n using albumin A. Is ass iated with agul pathy B. Is available as 1% r 5% s luti ns C. Can lead t pulm nary edema D. De reased a t r XIII
Answer: C Albumin is available as 5% ( sm lality 300 mOsm/L) r 25% ( sm lality 1500 mOsm/L). Due t in reased intravas ular n ti pressure, luid is drawn int the intravas ular spa e, leading t pulm nary edema when albumin is used r resus itati n r hyp v lemi sh k. Hydr xyethyl star h s luti ns are ass iated with p st perative bleeding in ardia and neur surgery patients. (See S hwartz 10th ed., p. 77.)
2. All are p ssible auses p st perative hyp natremia EXCEP A. Ex ess in usi n n rmal saline intra peratively. B. Administrati n antipsy h ti medi ati n. C. ransient de rease in antidiureti h rm ne (ADH) se reti n. D. Ex ess ral water intake.
Answer: C Hyp natremia is aused by ex ess ree water (diluti n) r de reased s dium (depleti n). hus, ex essive intake ree water ( ral r IV) an lead t hyp natremia. Als , medi ati ns an ause water retenti n and subsequent hyp natremia, espe ially in lder patients. Primary renal disease, diureti use, and se reti n antidiureti h rm ne (ADH) are mm n auses s dium depleti n. ADH an be released transiently p st peratively, r less requently, in syndr me inappr priate ADH se reti n. Lastly, pseud hyp natremia an be seen n lab rat ry testing when high serum glu se, lipid, r pr tein levels mpr mise s dium measurements. (See S hwartz 10th ed., p. 69.
30. A vi tim a m t r vehi le a ident arrives in hem rrhagi sh k. His arterial bl d gases are pH, 7.25; Po2 , 95 mm Hg; Pco2 , 25 mm Hg; HCO3-, 15 mEq/L. Te patient's metab li a id sis w uld be treated best with A. Ampule s dium bi arb nate B. S dium bi arb nate in usi n C. La tated Ringer s luti n D. Hyperventilati n
Answer: C In patients su ering r m hem rrhagi sh k, the presen e a metab li a id sis early in the p stresus itative peri d is indi ative tissue hyp xia due t persistent inadequate tissue per usi n. Attempts t rre t this pr blem by administering an alkalizing agent will n t s lve the basi pr blem. H wever, pr per v lume repla ement by means a balan ed salt s luti n su h as la tated Ringer s luti n will rest re per usi n and rre t the metab li a id sis by ending anaer bi metab lism. (See S hwartz 10th ed., p. 79.)
1. Metabolic acidosis with a n rmal ani n gap (AG) urs with A. Diabeti a id sis B. Renal ailure C. Severe diarrhea D. Starvati n
Answer: C Metab li a id sis with a n rmal ani n gap (AG) results r m either a id administrati n (HCl r NH4 +) r a l ss bi arb nate r m gastr intestinal (GI) l sses, su h as diarrhea, istulas (enteri , pan reati , r biliary), ureter sigm id st my, r r m renal l ss. he bi arb nate l ss is a mpanied by a gain hl ride, thus the AG remains un hanged. (See S hwartz 10th ed., p. 74.)
10. I a patient's serum glu se in reases by 180 mg/dL, what is the in rease in serum sm lality, assuming all ther lab rat ry values remain nstant? A. D es n t hange B. 8 C. 10 D. 12
Answer: C Osm ti pressure is measured in units sm les ( sm) r milli sm les (mOsm) that re er t the a tual number sm ti ally a tive parti les. F r example, 1 millim le (mm l) s dium hl ride ntributes t 2 mOsm ( ne r m s dium and ne r m hl ride). he prin ipal determinants sm lality are the n entrati ns s dium, glu se, and urea (bl d urea nitr gen [BUN]): Cal ulated serum sm lality = 2 s dium + glu se/18 + BUN/2.8 (See S hwartz 10th ed., p. 67.)
Water nstitutes what per entage t tal b dy weight? A. 30-40% B. 40-50% C. 50-60% D. 60-70%
Answer: C Water nstitutes appr ximately 50 t 60% t tal b dy weight. he relati nship between t tal b dy weight and t tal b dy water ( BW) is relatively nstant r an individual and is primarily a re le ti n b dy at. Lean tissues, su h as mus le and s lid rgans, have higher water ntent than at and b ne. As a result, y ung, lean men have a higher pr p rti n b dy weight as water than elderly r bese individuals. An average y ung adult male will have 60% his t tal b dy weight as BW, while an average y ung adult emale's will be 50%. he l wer per entage BW in w men rrelates with a higher per entage adip se tissue and l wer per entage mus le mass in m st. Estimates BW sh uld be adjusted d wn appr ximately 10 t 20% in bese individuals and up by 10% in maln urished individuals. he highest per entage BW is und in newb rns, with appr ximately 80% their t tal b dy weight mp sed water. his de reases t ab ut 65% by 1 year and therea ter remains airly nstant. (See S hwartz 10th ed., p. 65.)
25. I a patient's arterial Pco2 is und t be 25 mm Hg, the arterial pH will be appr ximately A. 7.52 B. 7.40 C. 7.32 D. 7.28
Answer: D A l w Paco2 indi ates ex ess eliminati n arb n di xide by the lungs, and the b dy pH will all. Within reas nable physi l gi ranges a 15 mm Hg all in Paco2 sh uld pr du e a 0.12 hange r m the n rmal b dy pH 7.4. (See S hwartz 10th ed., p. 74.)
An elderly diabeti patient wh has a ute h le ystitis is und t have a serum s dium level 122 mEq/L and a bl d glu se 600 mg/dL. Afer rre ting the glu se n entrati n t 100 mg/dL with insulin, the serum s dium n entrati n w uld A. De rease signi antly unless the patient als re eived 3% saline B. De rease transiently but return t appr ximately 122 mEq/L with ut spe i therapy C. Remain essentially un hanged D. In rease t the n rmal range with ut spe i therapy
Answer: D A rise in the extra ellular luid n entrati n a substan e that d es n t di use passively a r ss ell membranes (eg, glu se r urea) auses an in rease in e e tive sm ti pressure, a trans er water r m ells, and diluti nal hyp natremia. F r ea h 100 mg/dL rise in bl d glu se ab ve n rmal, the serum s dium level alls appr ximately t 3 mEq/L. Alternatively, the serum s dium level w uld in rease by ab ut 15 mEq/L i the bl d glu se level ell r m 600 t 100 mg/dL. (See S hwartz 10th ed., p. 69.)
21. Sympt ms and signs extra ellular uid v lume de it in lude all the ll wing EXCEP A. An rexia B. Apathy C. De reased b dy temperature D. High pulse pressure
Answer: D High pulse pressure urs with extra ellular luid v lume ex ess, but the ther sympt ms and signs are hara teristi m derate extra ellular v lume de i it. (See S hwartz 10th ed., p. 68.)
22. A l w urinary [NH4 +] with a hyper hl remi a id sis indi ates what ause? A. Ex essive v miting B. Enter utane us stula C. Chr ni diarrhea D. Renal tubular a id sis
Answer: D Metab li a id sis with a n rmal AG results either r m ex gen us a id administrati n (HCl r NH4 +), r m l ss bi arb nate due t GI dis rders su h as diarrhea and istulas r ureter sigm id st my, r r m renal l sses. In these settings, the bi arb nate l ss is a mpanied by a gain hl ride; thus, the AG remains un hanged. determine i the l ss bi arb nate has a renal ause, the urinary [NH4 +] an be measured. A l w urinary [NH4 +] in the a e hyper hl remi a id sis w uld indi ate that the kidney is the site l ss, and evaluati n r renal tubular a id sis sh uld be undertaken. Pr ximal renal tubular a id sis results r m de reased tubular reabs rpti n HCO3-, whereas distal renal tubular a id sis results r m de reased a id ex reti n. he arb ni anhydrase inhibit r a etaz lamide als auses bi arb nate l ss r m the kidneys. (See S hwartz 10th ed., p. 74.)
7. N rmal saline is A. 135 mEq NaCl/L B. 145 mEq NaCl/L C. 148 mEq NaCl/L D. 154 mEq NaCl/L
Answer: D S dium hl ride is mildly hypert ni , ntaining 154 mEq s dium that is balan ed by 154 mEq hl ride. he high hl ride n entrati n imp ses a signi i ant hl ride l ad up n the kidneys and may lead t a hyper hl remi metab li a id sis. It is an ideal s luti n, h wever, r rre ting v lume de i its ass iated with hyp natremia, hyp hl remia, and metab li alkal sis. (See S hwartz 10th ed., p. 76.)
All the ll wing treatments r hyperkalemia redu e serum p tassium EXCEP A. Bi arb nate B. Kayexalate C. Glu se in usi n with insulin D. Cal ium
Answer: D When ECG hanges are present, al ium hl ride r al ium glu nate (5-10 mL 10% s luti n) sh uld be administered immediately t untera t the my ardial e e ts hyperkalemia. Cal ium in usi n sh uld be used auti usly in patients re eiving digitalis, be ause digitalis t xi ity may be pre ipitated. Glu se and bi arb nate shi t p tassium intra ellularly. Kayexalate is a ati n ex hange resin that binds p tassium, either given enterally r as an enema. (See S hwarz 10th ed., p. 77.)
13. A patient with serum al ium 6.8 and albumin 1.2 has a rre ted al ium A. 7.7 B. 8.0 C. 8.6 D. 9.2
Answer: D When measuring t tal serum al ium levels, the albumin n entrati n must be taken int nsiderati n. Adjust t tal serum al ium d wn by 0.8 mg/dL r every 1 g/dL de rease in albumin. (See S hwartz 10th ed., p. 72.)
Te e e tive sm ti pressure between the plasma and interstitial uid mpartments is primarily ntr lled by A. Bi arb nate B. Chl ride i n C. P tassium i n D. Pr tein
Answer: D he diss lved pr tein in plasma d es n t pass thr ugh the semipermeable ell membrane, and this a t is resp nsible r the e e tive r ll id sm ti pressure. (See S hwartz 10th ed., p. 66.)
What is the a tual p tassium a patient with pH 7.8 and serum p tassium 2.2? A. 2.2 B. 2.8 C. 3.2 D. 3.4
Answer: D he hange in p tassium ass iated with alkal sis an be al ulated by the ll wing rmula: P tassium de reases by 0.3 mEq/L r every 0.1 in rease in pH ab ve n rmal (See S hwartz 10th ed., p. 71.)
18. Te a tual AG a hr ni al h li with Na 133, K 4, Cl-101, HCO3 - 22, albumin 2.5 mg/dL is A. 6 B. 10 C. 14 D. 15
Answer: D he n rmal AG is <12 mm l/L and is due primarily t the albumin e e t, s that the estimated AG must be adjusted r albumin (hyp albuminemia redu es the AG). C rre ted AG = a tual AG + [2.5(4.5 - albumin)] (See S hwartz 10th ed., p. 74.)
Te ree water de it a 70 kg man with serum s dium 154 is A. 0.1 L B. 0.7 L C. 1 L D. 7 L
Answer: D his is the rmula used t estimate the am unt water required t rre t hypernatremia =−×Water deficit Lserum sodium 140 140TBW Estimate BW (t tal b dy water) as 50% lean b dy mass in men and 40% in w men. (See S hwartz 10th ed., p. 69.)