Initial Impression: “Looks Good” vs. “Looks Bad”

Every skilled critical care nurse and physician develops a systematic method for determining the severity of the patient’s condition, making both qualitative and quantitative assessments. Often, the initial, general impression of how the patient looks is more important than any single vital sign or clinical measurement.^8a

The skilled critical care clinician can determine at a glance whether the patient “looks good” or “looks bad.” This determination requires a rapid visual evaluation of the child’s color, skin perfusion, level of consciousness (activity and responsiveness), breathing, and position of comfort (Box 1-1). Each portion of this assessment is reviewed in detail in this section.

The child’s color is normally consistent over the trunk and extremities. The child’s mucous membranes, nail beds, palms, and soles are normally pink. When cardiorespiratory distress is present, the skin is often mottled and extremities and mucous membranes can be pale. Although the mucous membranes of the adult with hypoxemia often become dusky, such central cyanosis (best observed in the mucous membranes) is not consistently detected in the hypoxemic child. The observation of cyanosis requires the presence of at least 3 to 5 g of desaturated hemoglobin per deciliter of blood, so the anemic child might never appear cyanotic despite the presence of profound hypoxemia. In addition, some healthcare providers have difficulty perceiving subtle color changes.

The child’s extremities are normally warm, with brisk capillary refill (2 s or less). When poor perfusion or stress is present, extremities are cool and capillary refill is often sluggish. Cold stress can also cause peripheral vasoconstriction and cooling of skin, particularly in extremities, so the environmental temperature should be considered when evaluating perfusion. If poor capillary refill is attributed to a cool environment, warm the patient and frequently recheck perfusion to determine whether the compromise in peripheral perfusion was caused by cold stress or if is actually caused by inadequate cardiac output.

A change in the child’s level of activity and responsiveness is often noted when systemic perfusion or neurologic function is compromised. Beyond a few weeks of age, the healthy infant will demonstrate good eye contact, orient preferentially to faces, and visually track brightly colored objects. The healthy infant should move all extremities spontaneously. In contrast, the infant in mild distress may hold all extremities flexed and demonstrate a facial grimace. The critically ill infant often will not sustain eye-to-eye contact and can be more irritable than usual, with a high-pitched or a very weak cry. As the infant deteriorates further, extremities will be flaccid, and the infant may be unresponsive.

The healthy toddler should protest vigorously when separated from the parents and should demonstrate stranger anxiety toward unfamiliar hospital personnel. The seriously ill toddler initially can be extremely irritable and comforted only by parents. With further deterioration, the toddler will be lethargic and unresponsive. The toddler normally will protest when the parents leave the bedside; lack of such protest is abnormal.

The healthy preschooler is typically distrustful or afraid of hospital personnel, but should be curious about equipment and tasks performed by the nurse or physician. At this age the child is usually able to localize and describe pain and symptoms. The school-aged child should be able to cooperate with procedures and answer questions about health, symptoms, and activities of daily living. The healthy school-aged child and adolescent are extremely self-conscious during physical examination. Initially, critical illness can make the child more irritable and uncooperative. As further deterioration occurs, the child will become lethargic and then unresponsive.

The healthy child of any age should respond to a painful stimulus (such as a venipuncture), and most children will attempt to withdraw from the stimulus. Therefore, a decreased response to painful stimuli is abnormal and usually indicates serious cardiorespiratory or neurologic deterioration.

The healthcare provider should evaluate the child’s breathing rate and effort, forming an opinion of the degree of distress that the child is demonstrating. The provider is reassured if the child is breathing at a regular rate that is appropriate for the child’s age and clinical condition. By contrast, the provider should be concerned about the child who is breathing rapidly, irregularly, or at a rate that is too slow for the child’s clinical condition, or if the child demonstrates significant effort (e.g., retractions, nasal flaring).

Most children prefer to sit upright in the hospital bed, particularly if strangers are present. The upright position is typically the position of comfort if respiratory distress is present, and the child will probably resist placement in the supine position. If the child reclines quietly in bed, then fear, pain, and serious illness are probably present. Young infants can’t assume a position of comfort, but may demonstrate less respiratory distress when the head of the bed is elevated.

Evaluation of Vital Signs

In the critical care unit, clinicians constantly evaluate the child’s general appearance (including breathing) and vital signs. Whenever possible the nurse should obtain “resting” information or measurements, including evaluation of heart rate and respiratory rate and effort, before disturbing the child. This resting information can be compared with information obtained when the child is awake and active. The child with upper airway obstruction can breathe comfortably when asleep, but demonstrate increased respiratory rate and effort while awake and active. Alternatively, if the child exhibits tachypnea with severe retractions even during sleep, more significant respiratory distress is present.

Normal vital signs are not always appropriate vital signs when the child is critically ill. The critically ill or stressed child should exhibit tachycardia and tachypnea; a “normal” heart rate and respiratory rate in such a child can indicate deterioration, and cardiorespiratory arrest might be imminent.

The child normally has a faster heart rate and respiratory rate and a lower arterial blood pressure than does an adult. As a result, smaller quantitative changes in the vital signs may be qualitatively more significant in the child than in the adult, particularly if they constitute a trend.

If the adult’s systolic blood pressure falls approximately 15 mm Hg, from 140/80 to 125/80 mm Hg, the mean arterial blood pressure has fallen 5%. However, if the infant’s systolic blood pressure falls 15 mm Hg, from 72/42 to 57/42 mm Hg, the infant’s mean arterial pressure has fallen about 10% and this change may be associated with a compromise in perfusion.

Normal vital signs ranges are provided in Tables 1-1 to 1-3. Evaluation of vital signs requires consideration of normal values for the child’s age,^14a trends in the individual patient’s vital signs, and appropriate vital signs for the child’s condition. Remember that in children, shock can be present despite the observation of a normal blood pressure. Hypotension is often a late sign of shock in the pediatric patient.

Table 1-1 Normal Heart Rates in Children*

* Always consider the patient’s normal range and clinical condition. Heart rate will normally increase with fever or stress.

Table 1-2 Normal Respiratory Rates in Children*^14a

* Consider the patient’s normal range. The child’s respiratory rate is expected to increase in the presence of fever or stress.

Table 1-3 Normal Blood Pressures in Children

The child’s heart rate and respiratory rate normally increase during stress and when the child is frightened or inpain, and they normally decrease when the child is sleeping. If vital signs are obtained when the child is crying, this should be indicated with the vital signs. Attempts should be made to comfort the frightened child, so that resting vital signs can be documented and evaluated.

Assessment Format

Consistent use of a familiar format will facilitate the nurse’s recall of important assessment information. The American Heart Association uses an ABC format to indicate assessment and support of airway, breathing, and circulation, and these priorities are still appropriate for assessment of the critically ill child.^8a In addition, all pediatric life support courses teach an initial assessment by determining the general impression of the child’s consciousness, breathing, and color; this text uses the “looks good versus looks bad” assessment. The skilled critical care clinician repeatedly performs these fundamental assessments.

An additional alphabetical format may be useful for pediatric critical care nurses. This format uses the first seven letters of the alphabet to help the nurse recall the steps in a seven-point check (Box 1-2). The seven essential assessment points include the child’s airway (and aeration), brain (neurologic function), circulation, drips or drugs administered, electrolyte balance, fluids (including fluid balance and fluid administration rate), genitourinary and gastrointestinal function, and growth and development.^17a When caring for the critically ill neonate, this format can be modified to create a nine-point check, with the addition of the letter H for heat, or thermoregulation, and the letter I for immunologic immaturity.

Thermoregulation

Infants and young children have large surface area-to-volume ratios, so they lose more heat to the environment through evaporation, conduction, and convection than do adults. In addition, the small child can lose heat if large quantities of intravenous or dialysis fluids are administered without warming.

Cold-stressed neonates and infants younger than 6 months cannot shiver to generate heat. When the environmental temperature falls, these infants maintain body temperature through nonshivering thermogenesis. This process begins with the secretion of norepinephrine and results in the breakdown of brown fat and creation of heat. Nonshivering thermogenesis is an energy-requiring process, so the infant’s oxygen consumption will increase whenever it develops. Regeneration of brown fat requires adequate nutrition; if the infant’s caloric intake is inadequate, brown fat will not be made to replace that used, and the infant will be less able to maintain body temperature in a cool environment.

Although the healthy infant is able to increase oxygen delivery in response to increased oxygen consumption during nonshivering thermogenesis, the critically ill infant may not be able to increase oxygen delivery effectively. As a result, cold stress can produce hypoxemia, lactic acidosis, and hypoglycemia. Cooling of the neonate also can stimulate pulmonary vasoconstriction, resulting in increased right ventricular afterload. For these reasons, cold stress can worsen existing cardiovascular dysfunction, causing increased heart failure or right-to-left intracardiac shunting.

The nurse can reduce cold stress by maintaining a neutral thermal environment for the neonate. A neutral thermal environment is the environmental temperature at which the infant maintains a rectal temperature of 37° C with the lowest oxygen consumption. This neutral temperature should be maintained during all aspects of the infant’s care, especially during transport and diagnostic tests. Over-bed radiant warmers can help maintain the infant’s temperature without interfering with observation and care. The beds are equipped with servo-control devices to adjust heat output in response to changes in the infant’s skin temperature. Adjustable alarms indicate when excessive warming is required to maintain the infant’s temperature or when the infant’s temperature varies from the selected range. (For further information regarding warming devices, see Chapter 21)

Unless there are contraindications (e.g., severe thrombocytopenia), nurses typically monitor both skin (e.g., axillary or via infant skin probe) and central (e.g., oral, esophageal, bladder) temperatures of critically ill infants and young children, because changes in these temperatures may be observed when systemic perfusion is compromised. Bladder temperature monitored via urinary catheter is an additional method of monitoring core body temperature.

Peripheral vasoconstriction and cooling of the skin is often an early sign of cardiovascular dysfunction and low cardiac output. The very young infant also can demonstrate a fall in core body temperature. The older infant or child with low cardiac output can demonstrate a low skin temperature with a normal or increased core body temperature, because heat generated by metabolism cannot be lost through the diminished skin blood flow.

Fluid Requirements and Fluid Therapy

The child’s daily fluid requirement is larger per kilogram body weight than that of the adult, because the child has a higher metabolic rate and greater insensible and evaporative water losses per kilogram body weight. Estimation of these fluid requirements is frequently based on the child’s body weight. However, evaporative water losses are affected directly by the child’s body surface area (BSA), determined by height and weight using a nomogram (see inside back cover), so calculations of fluid requirements are most accurate when based on the BSA.

If a BSA nomogram is not readily available, the BSA can be estimated using body weight and the following formula:

The weight can be estimated from body length using a length-based tape (see section, Cardiac Arrest and Resuscitation) such as the Broselow resuscitation tape (Fig. 1-1; see also Evolve Fig. 1-1 in the Chapter 1 Supplement on the Evolve Website.)

Fig. 1-1 Broselow Pediatric Emergency Tape. A, The two-sided tape allows for rapid identification of doses of emergency drugs, appropriate equipment sizes, and estimated body weight based on child’s body length. B, One side of the tape displays appropriate doses and administration volumes of resuscitation and rapid sequence intubation drugs and estimated weight (determined from child’s length). C, The second (color-coded) side of the tape indicates appropriate sizes of emergency equipment and additional fluid and drug information based on child’s length. (See also Evolve Fig. 1-1 in the Chapter 1 Supplement on the Evolve Website.)

(Used with permission of James Broselow and Vital Signs. Copyright Vital Signs, Inc. All Rights Reserved.)

The estimate of maintenance fluid requirements (Table 1-4) provides a baseline for tailoring the fluid administration rate for each patient. Actual fluid administration is tailored to the child’s clinical condition. Normal insensible water losses average 300 to 400 mL/m² BSA per day. Fever increases insensible water losses by approximately 0.42 mL/kg per hour per degree Celsius elevation in temperature above 37° C.⁴⁰ Radiant warmers, phototherapy, and the presence of diaphoresis or large burns also will increase a child’s insensible water loss. Fluid retention can diminish fluid requirements postoperatively and fluid retention typically develops in the presence of congestive heart failure, respiratory failure, or renal failure.

Table 1-4 Formulas for Estimating Daily Maintenance Fluid and Electrolyte Requirements for Children

* The “maintenance” fluids calculated by these formulas must only be used as a starting point to determine the fluid requirements of an individual patient. If intravascular volume is adequate, children with cardiac, pulmonary, or renal failure or increased intracranial pressure should generally receive less than these calculated “maintenance” fluids. The formula utilizing body weight generally results in a generous “maintenance” fluid total.

Although the child’s fluid requirements per kilogram body weight are higher than those of an adult, the absolute amount of fluid required by the child is small. Excessive fluid administration is avoided through careful regulation and tabulation of all fluids administered to the child. Unrecognized sources of fluid intake can include fluids used to flush monitoring lines or to dilute medications.

When the child is critically ill, hourly (or more frequent) evaluation of the child’s fluid balance is needed to enable rapid modification of fluid therapy in response to changes in the child’s condition. All intravenous and irrigation fluids should be administered through volume-controlled infusion pumps.

Many infusion pumps are programmable, and with entry of the child’s weight and drug concentration, the pumps will calculate drug dose administered by continuous infusion. Each nurse is responsible for all drugs administered during that nurse’s shift, so the accuracy of all infusion devices must be verified at the beginning of each shift and when changes are made in infusion rates, to avoid perpetuation of programming or other errors.

If hydration and fluid intake are adequate, the infant’s urine volume should average 2 mL/kg per hour. The normal urine volume will be 1 to 2 mL/kg per hour in the child and 0.5 to 1 mL/kg per hour in the adolescent. A small reduction in urine volume can indicate significant compromise in renal perfusion or function.

It is important to monitor and document all sources of fluid loss in the critically ill child. Unrecognized fluid loss can result from phlebotomy, nasogastric or pleural drainage, vomiting, diarrhea, or intestinal drainage. If fluid output exceeds intake, notify the appropriate provider; adjustment in fluid administration may be indicated.

Measurement of the child’s weight on a regular basis will aid in evaluation of the child’s fluid balance. You should ideally weigh the child using the same method (e.g., in-bed scale or the same external scale) at the same time each day, and at the same time in relation to diuretic administration, to avoid even small errors in measurement. Small daily weight changes can be significant, particularly if a trend is observed. A weight gain or loss of 50 g/day in the infant, 200 g/day in the child, or 500 g/day in the adolescent should be discussed with a physician or appropriate provider.

If the patient bed incorporates a scale, the bed scale should be zeroed before patient admission with a recorded list of the linens that are on the bed at the time of zeroing. If the linens and weights are not recorded, similar linens can be weighed, but this will obviously introduce error from one measurement to the next. If the bed does not incorporate a scale, sling scales are used. If possible, weigh bulky dressings and equipment before they are placed on the child. If this is impossible, record the weight of similar dressings and equipment to estimate their contribution to the child’s weight.

Children have proportionally more body water than do adults. Total body water constitutes approximately 75% to 80% of the full-term infant’s weight and 60% to 70% of the body weight of the adult. During the first weeks of life, most body water is located in the extracellular compartment, and much of this water is exchanged daily. For this reason and because the infant kidney is less able to concentrate urine (see section, Renal Function), dehydration can develop rapidly if the infant’s fluid intake is compromised or fluid losses are excessive.

Signs of dehydration are approximately the same in patients of any age and include dry mucous membranes, decreased urine volume with increased urine concentration, and poor skin turgor. The dehydrated infant usually will have a sunken fontanelle. Mild dehydration produces weight loss; moderate and severe dehydration generally produce signs of circulatory compromise. Peripheral circulatory compromise will be observed in the infant or child with moderate isotonic dehydration, but it may develop following mild dehydration in patients with hyponatremia. Moderate dehydration is typically associated with a 7% to 10% weight loss in children and a 5% to 7% weight loss in the adolescent or adult.

Oral intake often is compromised during serious illness, so the critically ill child depends on uninterrupted delivery of intravenous fluids. Because small intravenous catheters can easily kink and become obstructed, they must be handled carefully, anchored securely, and flushed regularly. When intravenous access is difficult to establish during resuscitation, intraosseous access provides a readily accessible and reliable route to administer fluids and medications.

Intravenous fluids are provided to flush monitoring lines, dilute medications, replace volume loss, or provide nutrition. In the past, hypotonic crystalloids (e.g., 5% dextrose with 0.2% sodium chloride) were routinely used for pediatric maintenance and replacement fluids, with the assumption that critically ill patients are likely to retain sodium and water. However, children are much more likely to develop hyponatremia if hypotonic rather than isotonic solutions are used, and isotonic fluids do not increase risk of hypernatremia.^2,9 At this time there is insufficient evidence to identify a single optimal intravenous fluid for pediatric maintenance therapy, so practitioners will need to individualize intravenous fluid selection for each patient.

Providers should monitor serum electrolytes and clinical status during parenteral fluid therapy to enable rapid detection and treatment of any imbalances that develop. The nurse should verify that the volume and content of each infusion is appropriate. If the patient’s status changes, it is often necessary to change the volume and content of the patient’s intravenous infusions.

The nurse should regularly inspect intravenous infusion sites and routinely touch every fluid administration system from beginning to end. With this careful inspection, the nurse will detect any loose connection or leak and can verify correct position of clamps and stopcocks; this inspection can prevent inadvertent interruption of or errors in fluid infusion.

Electrolyte, Glucose, and Calcium Balance

Normal serum electrolyte, glucose, and calcium concentrations are the same for both adults and children, as are renal and cellular mechanisms for maintaining serum electrolyte balance. However, some forms of electrolyte, glucose, and calcium imbalance are more likely to occur or cause complications in children than in adults. In addition, abnormalities of sodium, potassium, glucose, calcium, and magnesium occur frequently in critical care, so the nurse should monitor laboratory values and assess for clinical manifestations of these imbalances. It is important to anticipate the effect of therapy on the child’s electrolytes (e.g., correction of acidosis will be associated with a fall in serum potassium concentration) and attempt to prevent electrolyte imbalances.

Sodium is the major intravascular ion, and acute changes in serum sodium concentration will affect serum osmolality and free water movement. Hyponatremia in the critically ill child can result from antidiuretic hormone excess (i.e., the syndrome of inappropriate antidiuretic hormone secretion) and liberal water administration in excess of sodium, including administration of hypotonic fluids.⁴ Hyponatremia can also result from excess sodium losses, such as those occurring with adrenocortical insufficiency (see Chapter 12).

An acute fall in serum sodium will typically produce an acute fall in serum osmolality; this will produce an osmotic gradient from the extracellular compartment (including the vascular space) to the intracellular compartment, so free water shifts into the cells. A significant intracellular fluid shift can produce cerebral edema, seizures, and coma. The volume of water shift and the severity of clinical manifestations with hyponatremia are directly related to the acuity and the magnitude of the fall in serum sodium and osmolality. As in the adult, hyponatremia associated with neurologic symptoms is a neurologic emergency. In children it is treated with hypertonic saline (3% sodium chloride, 2-4 mL/kg).

Hypernatremia can result from excessive sodium administration or free water loss, such as that occurring with diabetes insipidus or vomiting. Hypernatremia in infants and young children is most frequently observed as a complication of dehydration. Cerebral hemorrhage and cerebral dysfunction have been reported after abrupt correction of hyponatremia in adults (i.e., rapid rise in serum sodium concentration),¹⁸ and similar complications are thought to occur in children. Rapid correction of hypernatremia can produce an acute fall in serum osmolality, with resultant intracellular free water shift and cerebral edema. In general, when correcting hyponatremia or hypernatremia the child’s serum sodium concentration should be changed at a maximum rate of 10 to 12 mEq/24 h (or an average of 0.5 mEq/h).

Changes in the serum potassium concentration occur with changes in acid-base status, use of cardiopulmonary bypass, and administration of diuretics. Hypokalemia can produce cardiac arrhythmias and perpetuate digitalis toxicity. However, cardiac arrhythmias related solely to potassium imbalance rarely occur in children until the serum potassium is extremely low (<3 mEq/L) or high (>7 mEq/L).

The serum potassium should be expected to fall as the child’s pH rises, and it will rise as the pH falls because hydrogen ion moves intracellularly in exchange for potassium. A low serum potassium concentration in a patient with acidosis is problematic, because it will drop even lower as the acidosis is corrected (see Chapter 12).

During periods of stress in adults, epinephrine and cortisol are secreted, resulting in glycogen breakdown and increased serum glucose levels; thus, the critically ill adult often demonstrates hyperglycemia. However, infants have continuously high glucose needs and low glycogen stores, so they often develop hypoglycemia during periods of stress. Hypoglycemia can depress the infant’s cardiovascular or neurologic function. Hypoglycemia or hyperglycemia can be an early sign of sepsis in the infant, and glycosuria can be an early sign of infection in the child.

All critical care clinicians will closely monitor the critically ill infant’s serum glucose concentration and treat hypoglycemia. If point-of-care testing is available, perform heel-stick glucose testing routinely, and treat and repeat as necessary during stabilization of the critically ill infant. A constant glucose infusion is preferable to frequent bolus administration of glucose; the infusion will prevent the wide fluctuations in glucose levels that can result from intermittent bolus glucose administration and reactive hyperinsulinemia. In many critical care units, 10% glucose solutions are used for intravenous maintenance fluid therapy for neonates.

Several case series in adult³⁸ and pediatric patients suggested that uncontrolled hyperglycemia, whether it is endogenous or exogenous in origin, can be harmful to critically ill patients and can increase complication rates and decrease survival. Although this is a significant concern, other studies have found contradictory evidence, and additional studies are underway to clarify these issues. Use of insulin infusion to prevent hyperglycemia was associated with reduced critical care unit mortality in adult studies³⁸ and one multicenter pediatric study,³⁹ but was also associated with increased hypoglycemic episodes.

The relative risk of hyperglycemia and potential harm from hypoglycemia must be considered and are currently being evaluated. If insulin is administered by continuous infusion to control hyperglycemia, it is typically used during the first 12 to 18 hours of pediatric critical care, with careful monitoring of serum glucose concentration using point-of-care testing, if possible. A glucose infusion can be added and titrated to prevent significant hypoglycemia during the insulin infusion.

The serum ionized calcium concentration (normal value is approximately 4.8 to 5.2 mg/dL or 1.2 to 1.38 mmol/L) is the “working” calcium, involved in nerve and muscle function.¹² Therefore, the healthcare team monitors ionized and total calcium concentration during critical illness and provides supplementary calcium for documented hypocalcemia.

A fall in total or ionized calcium is observed frequently in critically ill infants and children. Ionized hypocalcemia has been reported after cardiac arrest in children with septic shock or renal failure.⁴¹ The phosphate in citrate phosphate dextran-preserved blood will precipitate with ionized calcium, so some transfusions may produce ionized hypocalcemia.

The serum ionized calcium concentration is affected by the serum albumin concentration and by the serum pH. The ionized calcium concentration falls when the serum albumin or serum pH rise (both increase binding of calcium to albumin), and the ionized calcium concentration will rise when serum albumin or pH fall.

Abnormalities in magnesium balance are observed frequently in critically ill patients. Magnesium affects parathyroid function and contributes to control of the intracellular potassium concentration. As a result, hypomagnesemia can contribute to refractory hypocalcemia or hypokalemia. In addition, it can be associated with increased neuromuscular excitability, gastrointestinal dysfunction, and arrhythmias.¹⁸

Hypomagnesemia (<1.3 to 2.0 mEq/dL) in the critically ill child is most commonly caused by inadequate magnesium intake, particularly if the child is nutritionally compromised or receiving intravenous fluids without magnesium supplement. Hypomagnesemia is also observed in the child with increased magnesium losses, such as those that occur with chronic congestive heart failure or renal failure or following administration of osmotic diuretics.