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Biomedical subjects

K Bixby

Publications and source records attributed to K Bixby.

6 recordsLinked to original sources

Long-term outcome when major complications follow coronary artery bypass graft surgery. Recovery after complicated coronary artery bypass graft surgery.

OBJECTIVE: To determine whether information available 1 week after surgery correlates with long-term function in patients who suffer major complications after coronary artery bypass graft (CABG) surgery. DESIGN: An inception cohort study. SETTING: A 526-bed community teaching hospital. PATIENTS: All 67 patients who required at least 7 days of CT-ICU care following 2,751 consecutive CABG operations. MAIN OUTCOMES: Hospital survival, long-term survival, and functional ability at long-term follow-up. RESULTS: Forty-three patients survived hospitalization (64%), while 24 died 37 +/- 45 days (range, 7 to 190 days) after surgery. When 42 patients were surveyed 22 +/- 9 months after surgery, 21 of the survivors enjoyed excellent, independent function, 7 were moderately impaired but living at home, 6 were institutionalized with severe limitations, and 8 had died. Patients with very severe cardiac or neurologic dysfunction 1 week after surgery had an extremely poor outcome. When mechanical ventilation was required for causes other than primary failure of the respiratory system, long-term function and hospital survival were poor. Twelve of 14 patients with pulmonary complications survived hospitalization, and all 12 were alive at long-term follow-up. CONCLUSION: More than half of patients requiring 7 days or more of ICU treatment after CABG surgery survive, and many enjoy excellent long-term function. However, those with very severe cardiac or neurologic dysfunction 1 week after surgery have little chance for independent recovery.

Activities of Daily Living↗

Effect of positive pressure ventilation on impedance plethysmography.

It has been stated that positive pressure ventilation (PPV) may cause false positive impedance plethysmography (IPG) results because PPV can decrease venous outflow. We studied 36 patients who were being weaned from mechanical ventilation to determine the effect of PPV on IPG. Patients had IPGs performed during spontaneous ventilation and while receiving mechanical ventilation in the assist/control (A/C) mode without positive end expiratory pressure (PEEP) and with 10 cm H2O PEEP. No patient developed a positive IPG with institution of PPV (mean airway pressure = 6.8 cm H2O), or with PEEP (mean airway pressure = 14.9 cm H2O). The IPG values for venous capacitance and venous outflow did not change during either mode of mechanical ventilation. There also was no tendency for positive pressure ventilation to move IPG results in the direction of a positive test. In summary, PPV does not cause IPG results to be false positive, nor does it move IPG results toward the discriminant line that separates normal from abnormal results.

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Respiratory failure in the elderly. Analysis of outcome after treatment with mechanical ventilation.

BACKGROUND: Concerns about rendering futile care, the financial costs of mechanical ventilation, and aging of the population make it important to analyze the benefit of aggressive therapy for respiratory failure in the elderly. METHODS: This study is a retrospective review of 1860 patients treated with mechanical ventilation in the medical intensive care unit for more than 3 hours between 1974 and 1985. Patients were assigned to one of nine diagnostic groups, and 10 premorbid chronic illnesses or organ system dysfunctions were recorded. Survival to discharge was determined for all patients, and the duration of survival after discharge was determined for patients aged 80 years and older. Two hundred eighty-two patients aged 80 years and older were compared with 1578 patients less than 80 years of age. RESULTS: Fifteen percent of patients treated with mechanical ventilation were 80 years of age or older. Forty-four percent of patients younger than 80 years, and 30.9% of patients aged 80 years and older survived to discharge. Patients aged 80 years or older with preexisting renal disease, liver disease, cancer, systemic illness, or chronic gastrointestinal disease with malnutrition had only a 7% survival compared with 29% for younger patients. For patients without these premorbid conditions (80% of both the younger and older groups) survival among the elderly was better, even though it was still poorer than for younger patients (38% vs 49%). Elderly patients requiring more than 15 days of mechanical ventilation had a 9% survival compared with 36% for younger patients. CONCLUSIONS: A subgroup of patients 80 years of age or older can be identified whose chance for survival from respiratory failure is so poor that withholding or withdrawing treatment with mechanical ventilation may be appropriate. For the majority of elderly patients, short-term survival is nearly as good as in younger patients. Further studies are needed that assess long-term survival and functional recovery after treatment for respiratory failure so that elderly patients and their physicians can better decide whether or not to choose treatment with mechanical ventilation.

Age Factors↗

Reinfusion of shed blood after coronary operation causes elevation of cardiac enzyme levels.

We studied the effect of reinfusing mediastinal and chest tube drainage (autotransfusion) after coronary artery bypass grafting on circulating levels of creatine kinase, lactate dehydrogenase, and serum glutamic-oxaloacetic transaminase in 20 patients. Reinfusion of 469 +/- 171 mL (mean +/- standard deviation) of drainage caused enzyme levels to rise to 372% (creatine kinase), 159% (serum glutamic-oxaloacetic transaminase), and 143% (lactate dehydrogenase) of their levels before autotransfusion. The MB fraction of the circulating creatine kinase was not elevated. Enzyme changes caused by autotransfusion can potentially mimic or mask the presence of perioperative myocardial infarction. Enzyme determinations after coronary artery bypass grafting must be carefully interpreted when reinfusion of shed blood is used as a blood salvage technique. Routine measurement of these enzymes after operation may not be warranted.

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Acute cardiogenic pulmonary edema treated with mechanical ventilation. Factors determining in-hospital mortality.

We reviewed 88 episodes of cardiogenic pulmonary edema (CPE) treated with mechanical ventilation to define the clinical features that predict in-hospital mortality. Fifty-six patients survived to hospital discharge. APACHE II scores were not helpful in prediction. Multiple logistic regression models to predict outcome were developed using variables present at the time of intubation and 24 hours later. The model at the time of intubation indicated mortality was related to systolic blood pressure less than 130 mm Hg, the presence of anterior myocardial infarction, use of calcium channel blockers, age, and absence of prior hospitalization for CPE. A model using additional variables available 24 hours later showed that mortality was related only to the need for vasopressor medication at 24 hours, and systolic blood pressure at intubation less than 130 mm Hg. The predictive power of these models was confirmed by applying them to 46 additional patients. The variables contained in these models suggest that the prognosis of patients with CPE treated with mechanical ventilation depends primarily on the severity of acute left ventricular injury. Variables relating the degree of respiratory failure, however, were not predictive of mortality. These multiple logistic regression models provide a means to compare patients with CPE for quality assessment purposes and for studies of treatment regimens, and may also provide information useful to patient and family counseling regarding the value of continued aggressive intensive care.

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