Background: This study was undertaken to determine
whether alveolar dead space increases during intramedullary nailing
of femoral shaft fractures and whether alveolar dead space predicts
postoperative pulmonary dysfunction in patients undergoing intramedullary
nailing of a femoral shaft fracture.
Methods: All patients with a femoral shaft fracture
were prospectively enrolled in the study unless there was evidence
of acute myocardial infarction, shock, or heart failure. Arterial
blood gases were measured at three consecutive time-periods after
induction of general anesthesia: before intramedullary nailing and ten
and thirty minutes after intramedullary nailing. The end-tidal carbon-dioxide
level, minute ventilation, positive end-expiratory pressure,
and percent of inspired and expired inhalation agent were recorded
simultaneously with the blood-gas measurement. Postoperatively,
all subjects were monitored for evidence of pulmonary dysfunction,
defined as the need for mechanical ventilation or supplemental oxygen (at
a fraction of inspired oxygen of >40%) in the
presence of clinical signs of a respiratory rate of >20
breaths/min or the use of accessory muscles of respiration.
Results: Seventy-four patients with a total
of eighty femoral shaft fractures completed the study. Fifty fractures
(62.5%) underwent nailing after reaming, and thirty fractures
(37.5%) underwent nailing with minimal or no reaming. The
mean alveolar dead-space measurements before canal opening and at
ten and thirty minutes after canal opening were 14.5%, 15.8%,
and 15.2% in the total series of seventy-four
patients (general linear model, p = 0.2) and 20.5%,
22.7%, and 24.2% in the twenty patients with postoperative
pulmonary dysfunction (general linear model, p = 0.05).
Of the twenty-one patients with an alveolar dead-space
measurement of >20% thirty minutes after nailing,
sixteen had postoperative pulmonary dysfunction. According to univariate
and multivariate analysis, the alveolar dead-space measurement was
strongly associated with postoperative pulmonary dysfunction.
Conclusions: According to our data, intramedullary
nailing of femoral shaft fractures did not significantly increase
alveolar dead space, and the amount of alveolar dead space can predict which
patients will have pulmonary dysfunction postoperatively.