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Biomedical subjects

G Carlon

Publications and source records attributed to G Carlon.

At least 19 recordsLinked to original sources
PubMed1991

Use of neural network analysis to classify electroencephalographic patterns against depth of midazolam sedation in intensive care unit patients.

The electroencephalographic (EEG) analog signal is complex and cannot easily be described by univariate variables. Clear visual changes in the EEG power spectrum can be present with little or no change in univariate variable values. A method that could produce a single value based on the total data available in the EEG power spectrum would be very useful in monitoring EEG changes. Neural network analysis is a technique that can take multiple inputs and produce a single output value using complicated processing patterns that require training to establish. We examined the usefulness of a series of neural network models to classify 63 EEG patterns against sedation level in 26 mechanically ventilated patients requiring midazolam for long-term sedation. During a stable period of sedation, a 4- to 60-minute period of EEG data was obtained concurrently with a sedation level from 1 (follows commands) to 7 (no or gag response to suctioning of the endotracheal tube). The EEG power spectrum was divided into equal frequency bands, and the log absolute powers in each of these bands were used as inputs for a series of neural network models. The output target was the sedation level associated with each set of EEG data. Networks were trained on a subset of EEG power/sedation score data pairs, and the ability to classify the remaining data pairs was tested. Using a t-test comparison with a random set of sedation levels, we found that trained neural network models classified EEG patterns against sedation level successfully (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Tension pneumocephalus: treatment with controlled decompression via a closed water-seal drainage system. Case report.

The successful treatment of a patient with tension pneumocephalus by controlled decompression via external drainage is described. The advantage of the technique includes the immediate release of high pressure and the capability of maintaining constant low pressure to enable and facilitate sealing of dural tears. The method has been used in three other patients, leading to resolution of the tension pneumocephalus without recurrence or other complications.

Cerebrospinal Fluid Shunts↗
PubMed1984

Pneumatic-to-electrical analog for high-frequency jet ventilation of disrupted airways.

A pneumatic-to-electrical circuit analog is used to describe 2 separate mechanisms by which high-frequency jet ventilators sustain ventilation and oxygenation in the presence of large airway disruptions. The frequency-dependent mechanism is based on variations in the pneumatic equivalent to capacitive reactance. The pressure-dependent mechanism models lung defects on a voltage-controlled resistor. The electrical circuit model is also used to explain the factors leading to gas trapping and inadvertent positive end-expiratory pressure during high-frequency jet ventilation.

Airway Resistance↗
PubMed1981

The seventies evolution in liver surgery for cancer.

During the past decade, one of the major changes in the field of oncology has been in the surgical approach to primary and secondary cancer of the liver. As a result of data and experience gained in liver transplantation programs and with the application of vascular surgical principles, resectability rates have been increased. The present rate of 32% has been achieved with an overall 30-day operative mortality rate of 9%. More sophisticated intraoperative and postoperative supports have been essential in achieving these results. The median operating time is now 4 3/4 hours in length. Complications are minimal. The median postoperative hospital stay is now 13 days. During the past decade, 436 patients with liver tumors were treated by the authors. It has become apparent in this experience and in that reported by others that an increasing number of patients with primary liver cancer or metastatic cancer in the liver can be cured by surgery with minimal operative risk. Adjuvant chemotherapy may increase the salvage rate. Current therapeutic results are best evaluated after staging of the liver disease: Stage I (no involvement of margins of resection, hepatic vascular structures or bile ducts; all gross disease removed): 85% three-year survival estimate, using the Kaplan-Meier method, for individuals with primary liver cancer; 71% for those with metastatic colorectal cancer. Stages II and III (regional or extrahepatic spread): 22% three-year survival for individuals with primary liver cancer but no survivors at two years with metastatic colorectal cancer. These data permit better selection of patients who are most likely to benefit from surgery.

Adolescent↗
PubMed1981

High-frequency jet ventilation in major airway or pulmonary disruption.

High-frequency jet ventilation is an experimental method of mechanical support, which achieves satisfactory alveolar ventilation and oxygenation at low peak-inspiratory pressures of 5 to 8 cm H2O and low end-expiratory pressures of 3 to 5 cm H2O. This characteristic was used to advantage in 23 patients with cancer, 12 of whom had tracheal or bronchial disruption complicated by pneumonia. Eight patients who could not be supported by conventional means were salvaged. Barotrauma complicated the very high peak airway pressures required to ventilate 8 of 11 patients with respiratory failure associated with diffuse interstitial pneumonia or pulmonary fibrosis. There were only 2 survivors despite temporary normalization of arterial blood gas values in 7 patients. Earlier use of high-frequency jet ventilation in patients with poor compliance may prevent pulmonary disruption in addition to deleterious hemodynamic and systemic effects of conventional high-pressure ventilation. Other applications under study include the role of jet ventilation in resection of the trachea or carina, and in major airway trauma.

Acute Disease↗
PubMed1979

The inverse relationship between cost and survival in the critically ill cancer patient.

The enormous cost of intensive multiple organ system support is apparent from patient or third party charges of $1500--$2000 per day exclusive of physician fees sampled during a retrospective review of 700 consecutive recent admissions to the Critical Care Facility of Memorial Cancer Center. Mortality rates of 49% for general medical, 54% for lymphoma or leukemia, and 20% for surgery patients suggest the need for a selective admission and discharge policy which concentrates financial and personnel resources on those for whom there remains a reasonable chance of worthwhile palliation, if not cure, of their malignancy. An informal policy of this kind may have contributed to a 10% increase in hospital discharges and a reduction of in-unit mortality from 22--18% when compared to 1035 earlier unselected admissions. A modified version of the classification suggested by the Critical Care Committee of the Massachusetts General Hospital has been adopted for use at this institution. A similar approach by other cancer centers is urged so that predictive indices based on prognosis of the underlying disease as well as physiological status may be developed. Otherwise, cost-benefit analysis by third party payers or government will become an unavoidable, and less satisfactory, alternative.

Adult↗
PubMed1979

Multipurpose central venous access using the cordis sheath introducer system.

A nonpyrogenic polyethylene sheath system with a hemostatic valve assembly and side port extension developed by the Cordis Corporation is now routinely used for central venous access in critically ill patients. It is inserted percutaneously via the subclavian or internal jugular vein and allows rapid and efficient catheterization for hemodynamic monitoring, infusion of multiple solutions simultaneously, and uniflow hemodialysis. This system represents a significant advance in catheter technology.

Catheterization↗
PubMed1979

Airway management in the thrombocytopenic cancer patient with acute respiratory failure.

Prolonged endotracheal intubation has been the preferred approach when ventilatory support is required in thrombocytopenic cancer patients, because of concern for the possible hemorrhagic complications of tracheostomy. During the past 3 years, the authors have treated over 100 patients who developed acute respiratory failure while being treated for myeloproliferative or lymphoproliferative malignancies. This experience has suggested a greater incidence of potentially lethal complications among thrombocytopenic patients with prolonged endotracheal intubation than with early tracheostomy, which is now preferred in the critical care facility of this institution. Tracheostomy using electrocautery and careful technique has been performed without complication in 35 patients whose platelet counts were as low as 5,000-20,000/mm3.

Airway Obstruction↗