Which condition would directly compromise the average patients cardiac output?

SKIN ASSESSMENT

In addition to acrocyanosis and capillary refill delay discussed above, other findings can be seen in the skin. Fine downy hair, called lanugo, can develop on the trunk, arms, and face in undernourished patients as a method to maintain body heat. It will resolve as nutrition improves. Scalp hair can fall out from malnutrition and as it starts to reverse (the new, healthy hair pushes out the old). Cuts, abrasions, and calluses from using the hands to stimulate vomiting occur on the dorsum of the hand, called “Russell’s sign,” in honor of the first author on BN. Skin can also have pigment changes from excess intake of certain foods. A high proportion of carrots and pumpkin can cause an orange tint, and squash can cause a yellow discoloration. Conjunctival hemorrhages and swelling of the face and eyes can occur in those who vomit forcefully. Fortunately, all of these skin changes will resolve in time.

Mucous Membranes

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Normal membranes are pink with a capillary refill time of <2 seconds. Membrane pallor suggests poor perfusion or anemia (evaluate for intestinal parasitism, especially hookworm infection). Pallor and prolonged refill time suggest heart failure or reduced blood pressure with reactive vasoconstriction.

Cyanosis (blue-colored mucous membranes) develops from a low arterial oxygen tension with >5 g/dl of desaturated hemoglobin. Pulmonary dysfunction due to left-sided CHF or concurrent bronchopneumonia is the most common cause of cyanosis in CHD. Lesions that allow right-to-left shunting, such as tetralogy of Fallot, can lead to persistent or exercise-induced cyanosis in the absence of pulmonary dysfunction.

Right-to-left shunting requires a source of high right-sided resistance, and a communication or shunt proximal to the obstruction. With this combination, desaturated right-sided blood may enter the left side of the circulation.

Reasons for high resistance include PH from high vascular resistance, PS, mid-RV obstruction, and tricuspid valve disease (either stenosis or severe regurgitation that raises right atrial pressure).

The lesion allowing shunting can be a patent foramen ovale, ASD, VSD, or PDA. Additionally, in certain complex defects, there may be only a single great vessel exiting the heart; one ventricle that serves each great vessel; or transposition of the great vessels. Each of these situations allows mixing of pulmonary venous and systemic venous blood and may lead to cyanosis.

The term “differential cyanosis” generally refers to the condition of pink oral membranes and cyanotic caudal membranes (best seen in the vulva or prepuce). This is most typical of reversed PDA caused by a large ductus and severe PH.

Perfusion

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Heart rate

Mucous membrane color, CRT, palpable pulse pressures

Urine production: should be normal or increased after administration of intravenous fluids. Urine specific gravity can be used to help determine appropriate administration volume.

Cardiac contractility: M mode may be used to estimate this value. Contractility should be 35% to 50%, and chamber size should appear normal in addition to clinical evidence of euvolemia and/or normal CVP. In some hospitals, cardiac output can be measured by lithium dilution or sonographic method.

Arterial pressure: tail cuff or subjective digital pulse pressure. An arterial line can be established for recumbent foals (mean arterial pressure should be >65 mm Hg, ideally 120 to 130 mm Hg systolic pressure). The accuracy of the indirect monitoring of blood pressure using oscillometric measurements can vary depending on the following:

The ratio of bladder cuff width to tail circumference. No ideal ratio is known; however, a bladder width of 20% to 25% and length of 50% to 80% of the circumference of the tail is recommended. For foals, a 5.2-cm bladder width is recommended. The cuff can alternatively be placed over the metatarsus (great metatarsal artery) or the forearm (median artery) in foals.

The positional location of the cuff in relation to the level of the base of the heart. Practice Tip: This affects blood pressure measurements, as does the standing patient's head position; if possible keep the head in the same neutral position each time blood pressure measurements are performed.

At best, the indirect measurement gives an acceptable mean pressure and an indication of trends when performed intermittently in the identical manner and on the same patient. An accurate heart rate on the monitor should be displayed when blood pressure measurements are computed.

Practice Tips:

Mean arterial pressure <60 mm Hg without urine production is an indication for enhanced treatment and further monitoring.

Fluid therapy is the number 1 way of improving cardiac output and perfusion.

CVP should be 5 to 15 cm H2O for adults and 2 to 12 cm H2O for foals. Lower values are an indication for increased fluid rate, whereas high values are often, but not always, an indication for decreased fluid rate, pump therapy, and/or the possibility of renal failure. See Chapter 10, p. 35, for measurement of CVP.

Administer plasma protein, to a goal of ≥4.2 g/dL, to maintain oncotic pressure and prevent edema formation.

Practice Tip: Oncotic (osmotic) pressure should remain greater than 18 mm Hg in adults and 15 mm Hg in foals in order for crystalloid therapy to be most effective and to prevent edema formation.

What would be a direct result of increasing a patients preload?

What blood pressure change is most likely to cause left ventricular failure?

What situation could impair a patient's respiratory status?

Which one of the following conditions would most likely account for an elevated carbon dioxide level in a patient's body?