PATHO CORNER

Fluid and Electrolyte Imbalance: A BridgeOver Troubled Water

Kim A. Noble, PhD, RN, CPAN

THE DAILY INTAKE of water is taken forgranted, and the daily volume consumed isunappreciated. Perianesthesia patients are atrisk for the development of fluid and electro-lyte imbalances in a variety of ways: fluid defi-cits from the restriction of oral intake relatingto a ‘‘nothing by mouth’’ (NPO) status; theneed for gastrointestinal (GI) preparation andevacuation for abdominal surgery; insensiblefluid losses through the respiratory, skin, orGI tract; and/or blood volume losses relatedto the surgical procedure or the shifting offluid between body compartment(s). Peri-anesthesia patients receive replacement fortheir fluid deficit via intraoperative intrave-nous fluids, which at best is an estimate of ac-tual need and does not account for continuedlosses from postoperative nausea and vomit-ing or the inability to resume normal oral in-take postoperatively. Fluid status assessmentis a patient care priority of the perianesthesianurse, as the correction of fluid and electrolyteimbalances and the provision for an adequatefluid maintenance to prevent declines in organperfusion and to facilitate a rapid recoveryfrom surgery or anesthesia.

FF is a 58-year-old woman who has a familyhistory of metastatic colon cancer, the causeof death for her 55-year-old father. FF hasbeen very diligent with yearly colonoscopyand was found to have several malignantpolyps on her most recent study. She is sched-uled to have a radical polypectomy with possi-ble sigmoid resection under generalanesthesia today. FF is mildly obese, 5’8’’,200 pounds. She has a past medical historyof smoking for 20 years but quit

Journal of PeriAnesthesia Nursing, Vol 23, No 4 (August), 2008: pp 267-272

approximately seven months ago. FF hasmild hypertension and takes HydroDIURILdaily. FF has also had intermittent substernalchest pain and is scheduled to have a stresstest after she recovers from this surgery. FF isa second-grade teacher and reports havinggreat stress in her life.

She has been asked to arrive two hours beforeher scheduled procedure. She has a plannedadmission to the hospital and, pending theoutcome of her surgical procedure, plans tobe discharged the following day. She com-pleted an extensive bowel preparation and ar-rives into the same-day surgery unit feelingpoorly. A nursing assessment is completedand FF is found to have very dry skin andmucous membranes, dizziness with abruptchanges in position and the following vitalsigns: blood pressure (BP) 92/58, heart rate(HR) 118 beats/minute, respiratory rate (RR)28 breaths/minute and temperature of 99.1�F(tympanic). Her admission finger stick bloodsugar is 70 mg/dL. FF followed instructionsand did not take her morning diuretic dosage.Anesthesia is consulted and an intravenous(IV) line is started with lactated Ringer’s (LR)solution. Serum electrolyte results are ob-tained: Na1 158 mEq/L; K1 2.8 mEq/L; Cl–

115 mEq/L. Potassium chloride 20 mEq is

Kim A. Noble, PhD, RN, CPAN, is an Assistant Professor at

Temple University, Philadelphia, PA.

Address correspondence to Dr Kim Noble, Department of

Nursing, Temple University, 3307 N Broad St, Philadelphia,

PA 19140; e-mail address: knoble@temple.edu.

� 2008 by American Society of PeriAnesthesia Nurses.

1089-9472/08/2304-0008$34.00/0

doi:10.1016/j.jopan.2008.05.008

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268 KIM A. NOBLE

added to FF’s running IV solution. FF is unableto void on call to the OR and throughout the90 minutes before surgery the first liter of IVfluid infuses and a second bag of LR is hung.

FF is taken to the OR and anesthesia and sur-gery begin as planned. She is induced with100% oxygen, midazolam 2 mg, fentanyl 2mL, propofol 250 mg, and succinylcholine forrapid sequence induction. FF has a sigmoid re-section with anastomosis for adenocarcinomaof the colon. Lymph node sampling is com-pleted and the initial report indicates it is a non-metastatic lesion. FF’s procedure takes 95minutes and she was noted to have a single ep-isode of hypotension on induction despite fluidadministration. She remained mildly tachy-cardic throughout the procedure and had 5mg of the opioid agonist morphine sulfate ti-trated toward the end of the surgical proce-dure. An oral gastric tube was passed anddrained 100 mL of bilious fluid. FF’s bloodloss for the procedure was 450 mL. She re-ceived the maximal dose of pyridostigmineand glycopyrrolate and was extubated withoutdifficulty. Oxygen was applied by nasal cannulaand she was transported to the PACU.

Upon admission to the PACU, FF was noted tobe slightly restless, complaining of abdominalpain that was 7 on a 10-point pain scale. Ad-mission vital signs included BP 138/88, HR121 beats/min, RR 28 breaths/min and shal-low, a temperature of 96.1�F (tympanic), andoxygen saturation of 90%, which increasedto 93% with the application of a 40% aerosolmask. FF received 3,100 mL of LR intraopera-tively, plus the 1,000 mL that infused preoper-atively. Upon assessment, FF is noted to havebilateral breath sounds with decreased ex-change in the bases, a mildly obese abdomenwith a dry left-sided abdominal dressing, a Fo-ley catheter draining clear yellow urine, com-pression boots bilaterally intact, and palpabledistal pulses. Orders are received and FF isgiven a total of 6 mg of morphine sulfateover the next 30 minutes in 2-mg increments,with improvement of her abdominal pain to

4/10. She is changed to a 4-L nasal cannulawith a consistent saturation of 93% to 94%despite compliance with deep breathingrequests. Anesthesia is consulted and a chestradiograph is ordered and read as increasedinterstitial markings bilaterally. FF has receivedan additional 300 mL from her fourth bag ofLR. The infusion rate is decreased and FF isto remain in the Phase I PACU for an additionalhour of monitoring.

The Physiology of FluidCompartments and Osmosis

To understand the pathophysiology of fluidvolume abnormalities, one must first reviewnormal fluid balance and water movement,termed osmosis. Approximately 60% of totalbody weight is fluid, with two thirds of thatfluid found inside cells, termed the intracellu-

lar fluid, and one third found outside cells,called the extracellular fluid. The extracellu-lar fluid is further subdivided into the intersti-tial fluid, which surrounds the cells, and theintravascular fluid, or plasma, found insidethe blood vessels.1 A 70-kg patient wouldhave approximately 45 L of water in thebody. The total body water (TBW) is then di-vided into 30 L (2/3) found in the intracellularspace and 15 L (1/3) found in the extracellularfluid compartment. The extracellular compart-ment is further subdivided into intravascular,having 3 L of the 45 L of TBW, and interstitialhaving 12 L.2 Fluid compartments are sepa-rated by cell membranes, which limit themovement of protein and cellular componentsand allow the free movement of water.Ion concentration gradients are maintainedthrough the activity of energy-dependentpumps on the cell membranes.

Osmosis is a passive process in which watermoves as the result of physical processes with-out the expenditure of energy. Fluid first fol-lows protein concentration; for example,osmotic pressure, derived from the plasmaproteins, opposes the outward movement offluid from the vascular space. Patients with

FLUID AND ELECTROLYTE IMBALANCE 269

low serum protein levels (ie, albumin) are atrisk for edema, or the collection of fluid inthe interstitial space from the loss of osmotic‘‘pull’’ within the vascular space. Fluid alsomoves from an area of lower solute concentra-tion to areas of higher solute concentration. Asa memory cue, remember ‘‘salt sucks.’’ Thisform of fluid movement is a common causeof perianesthesia abnormalities in fluid andelectrolyte balance by the administration ofIV fluids during surgery.

The administration of IV fluids during surgeryrepresents the delivery of IV fluids directlyinto the intravascular space, one of the twosubdivisions of the extracellular space. The to-nicity, or the amount of solute (ie, Na1, glu-cose, or Na1 lactate), related to the amountof water of the IV solution is important be-cause the ion concentration will govern thefluid distribution within the body compart-ments. An example of osmosis from solute con-centration manipulation can be found with theadministration of hypertonic saline. Hyper-tonic saline adds Na1 to the vascular space,raising the Na1 concentration, leading to thepulling of fluid from the interstitial and intra-cellular spaces into the vascular space. In thesame fashion, the administration of fluid con-taining low Na1 concentration, a hypotonic so-lution, dilutes the Na1 in the plasma and leadsto the net movement of fluid out of the vascularspace and into the cells, where a higher con-centration of solute is present. Most com-monly, the IV fluid used for the replacementof surgical or insensible fluid losses is isotonic,or has a very similar solute to water concentra-tion, as is found in the vascular space. Thiswould not lead to the net movement of wateras found with the administration of hypertonicor hypotonic solutions, but is redistributedbased on normal compartmental distribution:two thirds into the intracellular space and theone third remaining into the extracellularspace. The movement of isotonic IV fluids istermed third spacing and can lead to edemain patients who have received large amountsof IV fluids perioperatively.3

Perianesthetic Fluid and ElectrolyteBalance

Patients having surgery or receiving moderatesedation for diagnostic procedures are atsignificant risk for fluid and electrolyte balanceabnormalities. These abnormalities may be de-rived from the preprocedure preparation, theadministration of anesthetics and anesthesiamanagement, or from the surgical procedureand associated fluid losses. Because each mayimpact patient presentation in the Phase Iand II PACU, careful assessment of fluid statusmust be conducted throughout the patient’ssurgical experience. For the ease of explana-tion, the potential for fluid losses has beendivided into preoperative and intraoperativeclassifications, which will be presented indi-vidually.

Preoperative Fluid Losses

Patients undergoing a surgical bowel prepara-tion self-administer osmotic laxatives, whichare designed to clear the bowel of fecal debris.As this induces diarrhea, patients may havelarge fluid losses. When a bowel preparationis added to the need of an NPO status aftermidnight the evening before surgery, signifi-cant dehydration may be present on admis-sion, as was seen in FF’s case. Dependent onskin turgor and preoperative vital signs, the ad-ministration of intravenous fluids may be indi-cated before the patient’s arrival to the OR.

Anesthetic Management and Intraoperative

Fluid Losses

Induction of general anesthesia may producea significant decrease in blood pressure fromcardiac depression and reduced cardiac out-put and decreased vascular resistance. Whenused with balanced anesthesia with benzodi-azepines and opioids, the induction agentdosage may be reduced.

Induction may lead to an exacerbation of hy-potension in a dehydrated patient and requirethe rapid administration of IV fluids. Mainte-nance fluids are given throughout the surgical

270 KIM A. NOBLE

procedure to replace blood loss and insensiblefluid losses from the pulmonary and GI tracts.Ongoing monitoring of urinary output may beused as a measure of renal perfusion and fluidstatus.

Fluid Replacement

Surgery and the administration of anesthesiainduce a systemic stress response, leading tothe activation of the endocrine system andthe initiation of an inflammatory response.Both lead to changes in fluid volume status, re-quiring volume expansion with fluid replace-ment. Fluid replacement is weight based,using formulas for accurate replacementbased on type of surgical procedure and resul-tant trauma. Fluid replacement ranges from 2mL/kg/hour of surgery for surgery with mini-mal trauma to 10–20 mL/kg/hour for majorsurgical trauma.4 Also calculated in the fluidreplacement is the time the patient receivedno oral intake and any estimated GI losses forsurgical bowel preparation. Usually the re-placement requirement is calculated and di-vided in half: the first half of the fluid isgiven over the first hour and the second halfis given over the next 2–4 hours with the main-tenance fluid. The volume and rate of infusionis also dependent on the patient’s past medicalhistory and overall health status.

This ‘‘cookie cutter’’ approach to fluid ad-ministration has been challenged recently.Difficulties are encountered in correct mea-surements for estimation of volume replace-ment. Arterial blood pressure measurementhas always been the gold standard for fluidreplacement, especially for the hypotensionassociated with anesthetic induction. Fluidreplacement research has uncovered limita-tions with the use of BP as a guide for admin-istration by the removal of 20–30% ofcirculating blood volume in healthy volun-teers without detectable changes in arterialpressure. However, a significant reduction intissue perfusion was noted.2 Fluid restriction(, 2 L/day) has been shown to statistically

increase return of bowel function (day 4)compared with patients receiving standardrates of fluid administration (.3 L/day).4 Asecond study of patients undergoing bowelresection after a ‘‘typical’’ bowel preparationreported significant differences between thegroup of patients who received liberal fluidreplacement (10 mL/kg bolus; 12 mL/kgmaintenance for 4-hour procedure) and re-strictive fluid replacement (maintenance fluiddecreased to 4 mL/kg for the 4-hour proce-dure). In the group receiving restricted fluidreplacement, one third required treatmentfor decreased urinary output with fluid bolusbut had a significant reduction in overall com-plication rate (17 of 77), whereas the liberalgroup had a much higher rate of complications(32 of 75).4 Much more research is indicated,with the inclusion of larger populations ofpatients, a variety of surgical procedures, andstandardization of fluid replacement treatmentgroups.5

Implications for the PACU Patient

The care of the perianesthesia patient re-quires a rapid but comprehensive assessment.Fluid and electrolyte abnormalities resultingfrom preoperative volume losses or surgicalor insensible losses in the OR and volume re-placement require careful assessment andmonitoring for rapid identification and treat-ment of potential problems. Intravenous ad-ministration represents the expansion of thevascular space, and in this fashion abnormali-ties may have a direct impact on tissue perfu-sion and organ function.

Alteration in Gas Exchange

A patient with abdominal surgery who arrivesto the Phase I PACU complaining of 7 out of 10abdominal pain, with a decreased oxygensaturation, creates a difficult decision for theperianesthesia nurse who is caring for thatpatient. On one hand, the abdominal painmay cause a decrease in saturation with theassociated increased pain with increasedrespiratory excursion. On the other hand, if

the decreased saturation has a different originthan abdominal pain, providing the patientwith an opioid agonist may exacerbate theproblem. In this instance, small doses of opi-oid should be given in incremental doses,with time allowed for the observation of effecton the respiratory status. This is even moreimportant for FF because she was given 10 mgof morphine sulfate at the end of the surgicalprocedure and additional opioids may havea cumulative effect.

Careful auscultation of breath sounds with fre-quent reassessment at intervals is needed. Thefindings should be correlated to the saturationand patient complaints of pain as the titratedopioid is delivered. Any unexpected devia-tions should be communicated to the anesthe-sia provider and additional orders received, aswas seen with the low–normal saturation andcompleted chest radiograph. The finding of in-creased interstitial markings on the chest ra-diograph is indicative of the movement offluid from the vascular space into the intersti-tial space. If this fluid movement continues,pulmonary edema and decreased diffusion ofoxygen and carbon dioxide may result. Post-operative orders for the continuous monitor-ing of saturation and oxygen administrationshould be obtained before the patient isdischarged.

Alteration in Cardiovascular Functioning

The finding of orthostatic hypotension preop-eratively was indicative of significant fluidlosses related to the surgical bowel prepara-tion completed at home by the patient beforeadmission. Large volume losses may be foundwith the development of pharmacologicallyinduced diarrhea and, when added to theNPO after midnight requirement by many an-esthesia care providers, may lead to significantfluid volume depletion. A patient who is dehy-drated may present complaining of feelingpoorly and may have orthostatic changes inblood pressure. As noted by research inhealthy volunteers, a decline in arterial bloodpressure may not be the best indicator of fluid

FLUID AND ELECTROLYTE IMBALANCE

status.2 For FF, this orthostatic hypotension isvery concerning because it was associatedwith tachycardia. An increased heart rate cre-ates two problems for the heart muscle; first,it increases the cardiac oxygen requirementsby requiring more frequent ion movement toaccompany a more rapid pump action, andsecond, it decreases the time of diastole whichis the only time the heart muscle receives a sup-ply of oxygen and nutrients via the coronaryarteries.3 When tachycardia, coupled by hypo-tension, is found in a patient with recurrentcomplaints of chest pain, fluid replacementis indicated.3 The addition of a decreasedserum K1 may indicate the need for a postop-erative electrocardiogram and electrolyte mea-surement.

Alteration in Fluid and Electrolyte Balance

FF arrived in the Phase I PACU with a lowsaturation, which improved slightly with theadministration of an opioid agonist and im-proved control of pain. When her saturationremained at a low–normal value, a chest radio-graph was ordered and findings of overhydra-tion were found. Overhydration may followgenerous replacement of estimated fluidlosses but may lead to the development ofpostoperative complications. Careful monitor-ing of respiratory and hydration status is indi-cated, necessitating the need for additionalPhase I PACU time. Diuresis may be indicatedif signs of decreased gas exchange develop,and careful intake and output measurementis very important. This may indicate theneed for the insertion of an indwelling urinarycatheter for accurate urinary output measure-ment.3

FF did not receive her morning dose of di-uretic and may require IV administration ofa diuretic until she is able to tolerate fluidsby mouth. Intravenous fluid orders should beobtained and careful administration ensuredwith the use of an infusion pump. An ongoingassessment should also be conducted to ruleout the development of dependent edema

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and any abnormal results communicatedrapidly to the anesthesia care provider.

Alteration in GI Function

FF’s sigmoid resection will necessitate a con-tinued NPO status until there is a return ofbowel function as indicated by the return ofbowel sounds. This ensures the need of hydra-tion with IV fluid administration and the needof continued careful assessment and monitor-ing of intake and output. Any episodic nauseaand vomiting should be treated promptly withthe administration of antiemetics as orderedby the attending physician. Vomiting shouldbe avoided because it may place strain onthe surgical incisions and lead to an increasein incisional pain. Early mobilization maydecrease the time required until the returnof bowel function and should be stronglyencouraged. Adequate pain management will

Refere

improve comfort for getting out of bed, cough-ing, or using incentive spirometry, and shouldbe provided.

In conclusion, FF was found to be at risk forthe development of a fluid status complica-tion. Careful assessment and ongoing monitor-ing of fluid intake and output preventeda more serious problem. FF demonstrated anincrease in the fluid in the interstitial space,which may impede normal gas exchange andplace her at risk for pulmonary complications.With careful monitoring and good communi-cation with the anesthesia care provider,a potential complication was minimized andadditional monitoring may have preventedadditional complications. Fluid replacementand management is necessary, but with dili-gent monitoring by the PACU nurse, complica-tions may be averted.

nces

1. McCance KL, Huether SE. Pathophysiology: The Biologic

Basis for Disease in Adults and Children, 4th ed. St Louis,

MO: Mosby; 2006.

2. Grocott MP, Mythen MG, Gan TJ. Perioperative fluid man-

agement and clinical outcomes in adults. Anesth Analg. 2005;

100:1093-1106.

3. Drain C, Odom-Forren J. PeriAnesthesia Nursing: A Criti-

cal Care Approach, 5th ed. St Louis, MO: Saunders; 2009.

4. Yeager MP, Spence BC. Perioperative fluid management: Cur-

rentconsensusandcontroversies.SeminDialysis. 2006;19:472-479.

5. Jacob M, Chappell D, Rehm M. Clinical update: Periopera-

tive fluid management. Lancet. 2007;369:1984-1986.