Mechanical Ventilation of Children After Marrow Transplantation: Not Just Small Adults?
Abstract & Commentary
Synopsis: A Canadian group reports that the outcome of mechanically ventilated children after bone marrow transplantation is superior to that reported in adults.
Source: Rossi R, et al. Crit Care Med 1999;27: 1181-1186.
Uniformly, the survival rates for patients requiring mechanical ventilation after blood and marrow transplantation have been dismal. Discharge from the ICU averages less then 20% and long-term survival is in the single digits. Rubenfeld and Crawford (Ann Intern Med 1996;125:625-633) reported specific postintubation complications that were associated with no survivors in a large cohort of patients. In the present study, Rossi and colleagues at the Hospital for Sick Children in Toronto reviewed the records of 355 consecutive bone marrow transplants in children (median age, 6.5 years). Mechanical ventilation was used in 39 children on 41 occasions. Overall, 17 of 39 patents were discharged from the PICU and 18 of 41 episodes of ventilation were successful. Six-month survival was 36%.
Patient characteristics such as malignant disease, transplant type, time after transplant, and organ dysfunction at admission to the PICU were not associated with outcome. Factors statistically associated with poor outcome were physiological score (PRISM), four or more organ failures, deterioration of lung function, and severe liver or renal dysfunction. However, there were survivors among many of these high-risk groups. On the basis of these results, Rossi et al believe that initiation of aggressive critical care treatment is warranted in pediatric marrow transplant recipients.
COMMENT BY STEPHEN W. CRAWFORD, MD
Rossi et al are to be commended on the high rate of success with mechanical ventilation after marrow transplantation. I wish I knew why they were so successful and whether their experience can be generalized to other centers.
There are several possible explanations for these results. One is that the children may not have been "that sick." The PRISM scores were relatively low on average, although multiple organ failures and low PiO2/FiO2 ratios were seen. I believe that many physicians are more likely to intubate and ventilate a sick child than a similarly ill adult. It is possible that ventilated children may be "less ill" than the average ventilated adult.
Regardless of the reason for the outstanding results reported by Rossi et al, they are vastly different from those reported by Rubenfeld and myself. Our report included adults and children. We did not see a survival rate anywhere near that reported by Rossi et al. Unfortunately, the two reports cannot be directly compared. The criteria for organ failure used by Rossi et al were different from those we used. It would be important to know whether any of the survivors in the Rossi study met the criteria we noted as associated with 100% mortality. Did any patients survive severe respiratory failure with associated sepsis and/or combined renal and hepatic failure?
From my perspective, the benchmark has been set for assessing mortality with mechanical ventilation after marrow transplantation. It is of relatively little value to state survival rates for specific patient groups without assessing whether the patients survived complications otherwise reported as 100% fatal.
I wholeheartedly concur with Rossi et al that aggressive intervention is warranted until one determines that the patient will not survive. The report by Rubenfeld and myself supports that same conclusion. Unfortunately, this study by Rossi et al does not help us determine when a child will not survive after marrow transplant once on the ventilator. That is when the dilemma begins.
Increased mortality with mechanical ventilation after bone marrow transplantation is not associated with:
a. autologous vs. allogeneic transplantation.
b. hepatic failure.
c. renal failure.
d. worsening respiratory status.
e. Any of the above
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