Minimizing respiratory complications of nasoenteric tube feedings: state of the science.

This article summarizes research findings regarding ways to minimize the two most dreaded complications of tube feedings: (1) introduction of feedings through tubes positioned in the respiratory tract, and (2) pulmonary aspiration. Bedside methods that lack reliability in ruling out inadvertent respiratory placement of feeding tubes include the auscultatory method, the bubbling under water method, and observing for respiratory symptoms. Testing the pH of aspirates from feeding tubes can be of use in ruling out respiratory placement of newly inserted tubes when acidic values are properly obtained; further, this method can also be helpful in determining when a tube has migrated from the stomach to the intestine. Based on experience, the most frequently cited values for excessive gastric residuals are 100 to 150 ml. In a recent small study, researchers concluded that the residual volume that should raise concern in patients with nasogastric tubes is 200 ml and in patients with gastrostomy tubes the amount is 100 ml. Several recent studies indicate that although elevating the head of the bed 30 to 45 degrees does not prevent aspiration, it does reduce its frequency and severity. Because many studies described in this review have not been replicated, readiness of their findings for clinical application is variable. Many questions regarding methods to prevent respiratory complications in tube-fed patients remain unanswered, largely because it is difficult to design clinical studies with sufficient control of significant variables.