Complications of Intra-Hospital Transport in Critically Ill Patients

Braman SS, Dunn SM, Amico CA, Millman RP Annals of Internal Medicine 1987 Oct. Pages 469-473

The authors conducted a prospective study involving 32 critically ill, ventilator-dependent patients who needed procedures done outside the intensive care unit (36 transports). The patients were accompanied during the entire trip by a physician, a registered nurse, and a registered respiratory therapist. During the first 20 transports, patients received ventilation from a manual resuscitation bag. Arterial blood gas measurements showed frequent changes from baseline with alterations in PC02 (>10 torr) or pH (>0.05) occurring on 14 occasions. In a subsequent study, 16 patients received ventilation in transit with the aid of a portable mechanical ventilator. Although 6 patients showed changes in arterial blood gas values, mean changes in PC02 and pH were significantly less than in the group that received manual ventilatory support (P<0.01). Hemodynamic complications of hypotension and cardiac arrythmia showed a significant correlation with disturbances in arterial blood gases (P<0.05). The authors note that in their experience, adequate oxygenation was easily and uniformly achieved by substantially increasing the oxygen concentration during transit. However, overzealous manual ventilation with resultant hypocarbia and respiratory alkalosis, or inadvertent underventilation, with resultant hypercarbia and respiratory acidosis, occurred in most of the patients evaluated. Because manual ventilation was performed by a trained respiratory therapist, the study shows that accurate, prolonged manual ventilatory support, especially during patient movement within the hospital halls and elevators, may be difficult to achieve. A simple volume meter might be used on the exhalation valve to ensure tidal volume and minute ventilation. Alternatively, portable end-tidal monitors of carbon dioxide can be used to ensure stable alveolar ventilation. Although limited by the lack of a control period, this study shows that the transport of critically ill patients may result in severe hemodynamic complications; it also suggests that these complications might be prevented by more careful monitoring of ventilation.