Supl79-02-b-ingles p65

Jornal de Pediatria - Vol.79, Supl.2, 2003 

 S157

Positioning therapy

The simplicity and low cost of the use of prone

positioning, associated with reports of improvements in

oxygenation in 60 to 70% of patients with ARDS has

made this therapeutic method popular. A number of

different mechanisms have been suggested to explain

this effect in patients placed in the prone position, such

as an improvement in the ventilation-perfusion

relationship,

52

 increased pulmonary volume at the end of

expiration

53

 and regional ventilation changes associated

with mechanical alterations of the thoracic wall.

54

However, as has been demonstrated above, improvements

in oxygenation do not necessarily translate to reduced

mortality in ARDS.

15

 Recently, Gattinoni and

colleagues

55

 reported the results of a multi-center,

controlled study in which patients with ARDS were

randomized to receive either conventional treatment

(supine position) or treatment in the prone position for 6

or more hours per day for 10 days. In this study, despite

causing an improvement in oxygenation, the use of the

prone position did not result in a reduction in mortality.

55

A number of different theories may explain these findings.

The simplest is that the use of the prone position indeed

does not prevent or attenuate the advance of pulmonary

injury in patients with ARDS. On the other hand, despite

including 304 patients, this study probably did not have

sufficient statistical power to reveal differences between

groups, since clinical studies of ARDS are marked by

heterogeneous characteristics demanding large sample

sizes. The patients randomized to the prone group assumed

the position for approximately 7 hours per day (or just

30% of the time) and for a maximum of 10 days. It is

possible that the limited duration of exposure to the

prone position could explain the failure of this strategy.

A multi-center study of pediatric patients with ARDS

involving the use of the prone position for the greater

part of the day and until resolution of the respiratory

failure is in progress in tertiary ICUs in North America.

Until concrete results are available, the recommendation

to place patients with ARDS in the prone position in an

attempt to improve oxygenation and allow exposure to

lower concentrations of oxygen appears to have a

reasonable theoretical foundation and few risks or costs

associated with it.

Prevention and early diagnosis of intercurrent

infections

As ARDS patients require invasive technology, such

as vascular and urinary catheters, endotracheal intubation

and mechanical ventilation for prolonged periods of

time, they are often the target of secondary infections,

especially pulmonary infections. Early diagnosis and

precise treatment of these infections is extremely

important, since secondary pneumonias act as an

additional pro-inflammatory insult. Radiologic diagnosis

of secondary pulmonary infections in patients with ARDS

is complicated by the fact that these patients exhibit pre-

existing radiologic abnormalities. Clinical diagnosis also

presents challenges, since symptoms such as fever,

leukocytosis and increased tracheal secretions may

already be part of the basic disease process. In clinical

practice, early diagnosis may be achieved by integrating

radiologic alterations, appearance and cellularity of

tracheal secretions and routine cultures (tracheal aspirate,

broncho-alveolar lavage and blood culture).

As with other nosocomial infections, prevention is the

best method of reducing the risk of secondary pulmonary

infections. Immunosuppressed or contagious patients should

be isolated and the use of universal contact precautions and

frequent hand washing are simple and highly effective

measures. Criteria-based antibiotic therapy guided by the

antibiogram of organisms isolated by cultures or on local

epidemiological data also plays an important role in the

prevention of secondary infections.

Analgesia and sedation

The comfort of patients with ARDS during their stay in

the ICU should occupy a prominent position in the therapeutic

strategy. Patients in the acute phase of the disease should

receive infusions of medications to reduce the emotional

stress and physical discomfort inherent to the pathology, as

well as in anticipation of painful procedures. Our practice

is to maintain patients with ARDS on continuous sedation

and pain relief, with these needs being reevaluated on a

daily basis. Infusions of midazolam (0.1 mg/kg/h) and

fentanyl (2 µg/kg/h) are used in the majority of patients and

doses are adjusted according to clinical requirements, with

doses of 10 times higher than the original not being

uncommon by the third week of the clinical course. Patients

subjected to permissive hypercapnia or HFOV require the

infusion of neuromuscular blocking agents, such as

vecuronium (0.1 mg/kg/h). Patients with highly

compromised pulmonary mechanics and during the acute

phase of the disease also often require neuromuscular

blocking agents.

Nutritional Support

Patients with ARDS have an elevated daily caloric

requirement as a function of the stress of trauma, sepsis,

surgery or the inflammatory process that accompanies

the lung injury in ARDS. These patients require prompt

institution of parenteral or enteral nutrition since a caloric

deficit can result in alterations of the defense mechanisms,

as well as delay lung healing. We prefer continuous

enteral nutrition via the naso-duodenal route, as soon as

technically feasible. Total parenteral nutrition should be

started immediately for patients who demonstrate

intolerance or contraindications to enteral nutrition.

Among potential complications of parenteral nutrition, it

should be noted that hypercapnia can occur as the result

of an excessive carbohydrate load through alterations in

the respiratory quotient.

Acute respiratory distress syndrome – Rotta AT 

et alii

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