I had several questions concerning the article, "Presurgical Risk Factors for Late Extubation in Medicare Recipients After Cardiac Surgery" (January/February 2004). Under the procedure section, information was given concerning study variables, however, no information was given concerning intraoperative variables. In order to effectively state the relationship of preoperative risk factors and comorbidities to duration of mechanical ventilation, I think it would be important to include information about the intraoperative variables of the sample population. In previous studies by Walthall, Robson, and Ray (2001) and Walthall and Ray (2002), information about standard type and amount of anesthesia, degree of hypothermia, ventilator settings, and postoperative pain control was included to control intraoperative variables. In this study, it is unclear what control factors were used concerning anesthesia, degree of hypothermia, ventilator settings, or postoperative pain control. For example, was the sample population given similar anesthetic during the procedure or was there variation in the drug used? The study by Walthall et al. limited the sample to persons who underwent surgery with the same surgeon. They found that by using only one surgeon they reduced variables such as surgical technique and myocardial protection techniques, which could have influenced their outcome. However, this study did not mention number of surgeons involved, or what surgical techniques were used.

Furthermore, Bezanson, Weaver, Kinney, Waldrum & Weintraub (2004), did not include information on extubation criteria. Doering (1997) included a standardized early weaning and extubation protocol, which the nurse used to assess the patient hourly in order to determine correct timing for extubation. Walthall et al. (2001) and Walthall & Ray (2002) included a similar tool used to determine extubation timing. In both studies, the patients were not extubated until the set criteria were met. In this study, no clear information was given about criteria set for determination of extubation (i.e., patient alertness, level of pain, respiratory rate, or blood gas measurements) How did the researchers know that each of the patients were extubated under the same conditions, which may or may not have affected the results of their study? Although this study focused on preoperative risk factors related to late extubation, intraoperative factors must be considered in the timing of extubation after cardiac surgery (Walthall et al., 2001 and Doering, 1997). Additional information about the sample population and control variables would be helpful in determining the relevance of the data reported. I agree with the authors of this study that additional research and further development of a predictor model is necessary before this information is used by practicing clinicians.

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