Basic Concepts of Fluid and Electrolyte Therapy

More documents

Recommendations

Info

Prolonged periods of preoperative fasting cause patients to reach the anaesthetic room in a state of fluid depletion, which may be further compounded by indiscriminate bowel preparation, another practice that has not been shown to have a positive effect on surgical outcome. Current anaesthetic recommendations that allow patients to drink clear fluids up to 2 h prior to the induction of anaesthesia prevents preoperative fluid depletion and do not increase aspirationrelated complications. On the other hand, the practice of prescribing large amounts of salt containing fluids in the perioperative period causes salt and water overload with adverse effects on surgical outcome. Although the daily maintenance requirements for sodium and water are estimated at 1 mmol/kg and 25-35 ml/kg to support the integrity of the extracellular fluid volume, it has not been unusual for patients to receive in excess of 5 L water and 700 mmol sodium (and chloride)/day in the early postoperative period. In evolutionary terms, the metabolic response to trauma involves salt and water retention in order to preserve intravascular volume. However, when large volumes of salt containing fluids are administered, most of the excess accumulates in the extravascular compartment and causes oedema, which is detrimental to surgical outcome. Most of the retained fluid after such infusions accumulates in the interstitial compartment, leading to manifest oedema if overload exceeds 2-3 L. In the face of acute illness, injury, or surgery, and also of severe malnutrition, the capacity to excrete a salt and water load is further impaired, only returning to normal during convalescence. An overload of 0.9% saline in such cases can cause hyperosmolar states, hyperchloraemic acidosis, decreased renal blood flow and glomerular filtration rate, which in turn exacerbates sodium retention. Oedema impairs pulmonary gas exchange and tissue oxygenation, and leads to an increase in tissue pressure in organs such as the kidney which are surrounded by a non-expansible capsule, thereby compromising 118
microvascular perfusion, increasing arterio-venous shunting and reducing lymphatic drainage, all of which facilitate further oedema formation. Fluid accumulation in the lungs also increases the risk of pneumonia. Removal of excess alveolar fluid is achieved by active sodium transport and the gradient between the hydrostatic and colloid osmotic pressures. Active sodium transport is affected by fluid administration and by the release of proinflammatory cytokines, both of which occur perioperatively. Acidosis impairs cardiac contractility, reduces responsiveness to inotropes, decreases renal perfusion and can be lethal in combination with hypothermia and coagulopathy. Hyperchloraemic acidosis, as a result of saline infusions has been shown to reduce gastric blood flow and decrease gastric intramucosal pH in elderly surgical patients, and both respiratory and metabolic acidosis have been associated with impaired gastric motility. Just as fluid overload causes peripheral oedema, it may also cause splanchnic oedema resulting in increased abdominal pressure, ascites and even the abdominal compartment syndrome. Consequently, this may lead to a decrease in mesenteric blood flow and a further exacerbation of the process, leading to ileus, delayed recovery of gastrointestinal function, increased gut permeability, intestinal failure and even anastomotic dehiscence. Fluid excess may also impair postoperative mobility and increase the risk of deep vein thrombosis, nausea, vomiting, abdominal pain, hyperventilation, headaches, thirst, confusion and diplopia. The literature suggests that, for most purposes, a balanced electrolyte solution is superior to 0.9% saline and a comprehensive review of the use of 0.9% saline for resuscitation has recommended that its routine use in massive fluid resuscitation should be discouraged. On the other hand, true fluid restriction resulting in underhydration can be equally detrimental by causing decreased venous return and cardiac output, diminished tissue perfusion and oxygen delivery, increased blood viscosity, decreased saliva production with a predis- 119
Page 1 and 2:
Dileep N. Lobo Andrew J. P. Lewingt
Page 3 and 4:
Basic Concepts of Fluid and Electro
Page 5 and 6:
Foreword This book, ‘Basic Concep
Page 7:
Table of Contents 1. Normal Physiol
Page 10 and 11:
ever, contains large anions such as
Page 12 and 13:
Oral intake 1.5-2 L Saliva 1.5 L Ga
Page 14 and 15:
Table 2: Normal maintenance require
Page 16 and 17:
Kidney: this is the main organ for
Page 18 and 19:
Conversely, if the intake of Na + i
Page 20 and 21:
volume at all costs. It also explai
Page 22 and 23:
Conclusion Appropriate fluid therap
Page 24 and 25:
Intravascular fluid volume - the to
Page 26 and 27:
Colloid - a fluid consisting of mic
Page 28 and 29:
Base excess - Base excess is define
Page 30 and 31:
Parameter Urine output Significance
Page 32 and 33:
Figure 5: Example of a vital signs
Page 34 and 35:
Fluid balance charts These provide
Page 36 and 37:
Osmolality In the presence of AKI,
Page 38 and 39:
Chloride Despite the fact that seru
Page 41 and 42:
4. Properties of Intravenous Crysta
Page 43 and 44:
6-12 h. The colloid should be metab
Page 45 and 46:
Table 8: Advantages and disadvantag
Page 47:
Plasma- Sterofundin 0.18% Plasma-Ly
Page 50 and 51:
50 Patients receiving artificial nu
Page 52 and 53:
Once resuscitation has been achieve
Page 54 and 55:
(3) The answer to this question is
Page 57 and 58:
6. Methods of Fluid Administration
Page 59 and 60:
Central Modern single or multi lume
Page 61 and 62:
7. Acid-Base Balance Introduction M
Page 63 and 64:
vide a simple description of the mo
Page 65 and 66:
change in Pco 2 = respiratory proce
Page 67 and 68: Table 15: Causes of metabolic acido
Page 69 and 70: Renal HCO 3 - loss results from re
Page 71: Mixed acid-base disorders These are
Page 74 and 75: Urine output should be interpreted
Page 76 and 77: assess clinical response to fluid i
Page 78 and 79: Oliguria following surgery 48 h and
Page 80 and 81: Definition AKI is a result of a rap
Page 82 and 83: AKI is most commonly secondary to a
Page 84 and 85: History Examination Investigations
Page 86 and 87: Management Prevention Any patient a
Page 88 and 89: if no clinical response and no pulm
Page 90 and 91: acidosis pH 7.2-7.4 - there is ver
Page 92 and 93: Referral to nephrologist NOT all p
Page 94 and 95: Follow up Acute kidney injury is a
Page 96 and 97: DKA and HONK represent the two extr
Page 98 and 99: Fluids and insulin In the absence
Page 100 and 101: Surgery in the patient with diabete
Page 102 and 103: 10 mmol/l/day. In the differential
Page 104 and 105: portionately more water is lost tha
Page 106 and 107: Hypokalaemia: a fall in serum conce
Page 108 and 109: Four common aspects of Ca 2+ disord
Page 110 and 111: Treatment depends on severity and c
Page 112 and 113: 112
Page 114 and 115: Hypophosphataemia
Page 116 and 117: 116
Page 120 and 121: position to postoperative parotitis
Page 122 and 123: 13. *Chowdhury AH, Lobo DN. Fluids
Page 124 and 125: 42. Hussein H, Lewington A, Kanagas
Page 126 and 127: 67. *Michell AR. Diuresis and diarr
Page 128 and 129: 94. *Stewart PA. Modern quantitativ
Page 130 and 131: colloids 7, 26, 41, 42, 43 44, 45,
Page 132 and 133: intravascular compartment 20, 41, 4
Page 134 and 135: Stewart approach 63, 71 sympathetic
Page 136: Dileep N. Lobo Andrew J. P. Lewingt
show all

Basic Concepts of Fluid and Electrolyte Therapy

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?