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26  Fluids and Electrolyte Therapy in the Paediatric Surgical Patient 
        Table 5.4: Signs and symptoms of dehydration.          cardiovascular  instability  are  all  symptoms  commonly  seen  when  a
                                                                                               4
                                                               paediatric  patient  has  severe  dehydration.   Some  common  surgical
          Percent of body   Signs and symptoms of dehydration
             weight                                            paediatric  issues  that  can  cause  severe  dehydration  include  bowel
                                                               obstruction,  acute  burns,  intestinal  perforation,  myelomeningocele
                        • History of 12–24 hours of vomiting and diarrhoea  (open), and trauma. Table 5.4 presents signs and symptoms of dehy-
         1–5% (mild)    • Dry mouth                            dration by percentage of body weight. 5
                                                                 The compensatory mechanisms for dehydration that are seen in the
                        • Decreased urination
                                                               adult population are less well defined in the term infant and even less so
                        • Tenting skin                         in the preterm infant. The body’s primary mechanism for compensation
                                                               is the renin-angiotensin-aldosterone system, which attempts to absorb
                        • Sunken eyes, fontanelle
         6–10% (moderate)                                      sodium  and  water.  Renin  is  released  from  the  kidneys,  which  then
                        • Oliguria                             prompts  the  release  of  aldosterone  and  ADH,  which  then  allows
                        • Lethargy                             for  the  water  and  sodium  to  be  reabsorbed. The  newborn  is  able  to
                                                               allocate some of the extracellular fluid to the plasma volume, but this
                        • Cardiovascular instability: mottling, hypotension,   compensation is limited and will result in the loss of skin turgor. The
                         tachycardia                           newborn’s cardiac output is determined by the heart rate because the
         11–15% (severe)
                        • Anuria                               intrinsic heart muscle is noncompliant, therefore making the adjustment
                        • Sensorium change                     in preload volume very difficult. If a patient arrives in a state of severe
                                                               dehydration  and  shock,  then  the  infusion  of  20–30  ml/kg  of  normal
                        • Coma                                 saline  must  be  started  while  others  monitor  for  the  improvement  in
         20%
                        • Shock                                fluid  status.  Urine  output  and  concentration  (appearance)  will  be
                                                               the  most  accurate  and  cost-effective  measurements  that  will  allow
                                                               for  the  monitoring  of  the  overall  fluid  status.  The  placement  of  an
        Glucose Requirements                                   intraossaeous  line  is  now  preferred  if  a  peripheral  intravenous  line
        Carbohydrate reserves are relatively low in the newborn and certainly   cannot  be  placed  quickly  during  the  resuscitation  time  in  a  severely
        will drop to low levels during the prolonged labour course often seen in   dehydrated child. Studies have shown that normal saline is as good a
        some areas of Africa. Thirty percent of the glucose reserves are stored   volume resuscitator as any fluid available (Table 5.5), and it certainly
        as glycogen in the liver, but this cushion is less evident in the low-birth-  is cost effective; therefore, there is no need to use the more expensive
        weight or preterm infant. Within the first four hours of life, the newborn   colloids during fluid resuscitation.
        must be given some form of glucose. With prematurity and a gestational   NPO Period in the Paediatric Population
        age of less than 34 weeks, the ability to swallow is low, so the patient   There has been considerable debate about NPO status in children, and
        may  need  an  intravenous  (IV)  line  or  a  feeding  tube. Adequate  and   NPO guidelines have undergone adjustment. At this time, we no longer
        frequent measurement of the glucose levels of the newborn, especially   use  the  former  prolonged  times  that  once  produced  surgical  patients
        the newborn pending surgery, is cost effective and will help manage the   who were relatively volume depleted upon the start of surgery. It has
        hypoglycaemia and hyperglycaemia episodes that may harm the infant.  been shown that clear liquids given 3 hours before surgery results in a
           Children  who  are  small  for  gestational  age  (SGA),  have  chronic   lower gastric volume and no change in gastric acidity. A clear liquid
        illnesses, had a prolonged NPO (nothing by mouth) period, premature   is  one  that  has  no  particulate  matter,  which  means  that  you  can  see
        infants, and infants of diabetic mothers are all at risk for hypoglycaemia   through the fluid if held up to the light without obstruction.
        during  their  hospital  course.  In  SGA  infants,  hypoglycaemia  usually   Infants who are on formula need 6 hours, and breast-feeding infants
        occurs 24–72 hours after birth, when the glycogen stores are depleted and   need 4 hours, at our institution in Kenya, but at some hospitals this
        the breast milk production may not yet meet demand. In Kenya, we use D   would be considered a “clear” liquid and only 3 hours are required for
        10 (80 ml) mixed with normal saline (NS; 20 ml) in a buretrol of 100 ml   NPO.  These  modifications  have  allowed  for  situations  in  which  the
        and then begin our maintenance fluids and monitor blood glucose levels.   children’s veins are more distended and, hopefully, children and parents
        The 60 drops per ml buretrols allow us to give the appropriate volume of   who are happier during the preoperative period. The type of surgery and
        fluids, which will prevent volume overload (never place more than the   reason for the surgical intervention will also dictate the ability to take
        volume for 4 hours of maintenance fluids in the buretrol) while adapting   fluids  by  mouth.  Many  neonates  who  need  emergency  surgery  have
        the amounts of dextrose and normal saline based upon basic lab values.  never been on any fluids, and NPO is not an issue, but if the patient has
           Glucose level instability is commonly seen in those patients who are   a bowel obstruction, for example, then the need for a rapid sequence
        septic or have had a period of hypotension or asphyxia. These patients   induction (anaesthesia) may override any NPO concerns.
        need  close  monitoring  every  hour  in  the  operating  theatre  to  adjust   Intraoperative Fluids
        glucose levels; they all need glucose in their operative fluids to prevent   The calculation of intraoperative fluid requirements can be allocated
        the severe complications associated with hypoglycaemia. Intraoperative   into the following sections: maintenance fluids, preoperative fluid defi-
        glucose administration is controversial but, in general, 5% dextrose is   cit, insensible losses, and estimated blood loss (Table 5.6). Maintenance
        adequate because the metabolic stress response to surgery will avoid the   fluids per hour required based upon a patient’s weight was discussed
        patient becoming hypoglycaemic. Neurosurgical cases need very close   earlier;  typically,  normal  saline  or  Ringer’s  lactate  are  the  fluids  of
        glucose control due to cerebral ischaemia issues and hyperglycaemia.
                                                               choice,  as  they  most  closely  represent  the  plasma  components.  The
         Perioperative Fluid and Electrolyte Management        preoperative  deficit  will  be  the  patient’s  weight  in  kilograms  multi-
        Dehydration                                            plied by the number of hours without any fluids. The insensible losses
                                                               depend upon many factors, but primarily will be based upon the size of
        The severity of dehydration should be estimated based upon the his-
                                                               the incision and whether exposure of the bowel or viscus is involved,
        tory  and  clinical  findings.  There  are  no  unique  lab  values  that  can
                                                               as this will increase fluid loss (see Table 5.6). The estimated blood loss
        accurately  determine  the  severity  of  dehydration,  but  certainly  an
                                                               needs to be replaced as well, with a ratio of 3 ml of normal saline for
        experienced  medical  care  provider  becomes  adept  at  the  estimation
                                                               every 1 ml of blood loss.
        of  dehydration  in  the  paediatric  population.  Oliguria,  lethargy,  and
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