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Biomedical subjects

R W Martin

Publications and source records attributed to R W Martin.

At least 181 records · Page 10Linked to original sources
PubMed1986

Acute management of sickle cell crisis in pregnancy.

Vaso-occlusive sickle cell crisis (VSCC) is the most common maternal complication in pregnancies associated with sickle hemoglobinopathies. Maternal and fetal morbidity and mortality secondary to this serious obstetric problem can be reduced significantly with a well-devised therapeutic plan, expert perinatal teams, and careful attention to obstetric and medical detail in a setting of comprehensive tertiary health care. A variety of better medical, obstetric, and neonatal care practices have helped considerably to improve the combined life span for affected mothers and fetuses. In the absence of any effective and safe pharmacologic agent to prevent sickle crisis, our experience suggests that adherence to the described management principles offers the greatest hope to the sickling parturient that her vaso-occlusive crises can be effectively managed for a healthy outcome, both for herself and for her baby.

Anemia, Sickle Cell↗
PubMed1985

Clinical management of sickle cell hemoglobinopathies during pregnancy.

Although the maternal and perinatal morbidity as well as mortality in pregnant patients with sickle cell disease is significantly higher than those parturients with hemoglobin A, marked amelioration has been obtained by comprehensive health care utilizing expert perinatal teams and by providing careful attention to preventive measures for infection and crisis. Through these consistent efforts, the life span for the mother/fetus/newborn has improved considerably over that observed in the past. Although there is no present cure for sickle cell disease and no effective and safe physiologic treatment in a preventive sense, our experience suggests that adherence to careful management principles, offered in this article, will increase the likelihood that significant vaso-occlusive crisis and infection can be reduced, thus resulting in a healthier pregnancy outcome. In addition, the future is bright for the development of pharmacologic agents to prevent sickle cell crisis and for advances in techniques designed to induce endogenous production of normal hemoglobin.

Blood Transfusion↗
PubMed1984

Effects of cardiac output on the clearance of air emboli from the superior vena cava.

The authors assessed the effect of cardiac output on the rate of clearance of air emboli from the superior vena cava (SVC) in 11 dogs placed in a supine 30 degrees head-up inclined position. Venous air emboli were produced by infusing 4 ml of air into the dorsal sagittal sinus. Air emboli appearance and clearance from the SVC were determined from the analog record produced by a transesophageal Doppler ultrasound monitor. Cardiac output was altered by changing the level of anesthesia and the administration of intravenous fluid. Eighty-eight per cent of air infusions resulted in an analog response of consistent amplitude indicating that all or a similar fraction of the infused air arrived consistently at the ensonified region of the SVC. In this group, air emboli passed from the SVC with a clearance time (CT) that was related inversely to the cardiac index (CI). CT = 24 CI-1.3 with a correlation coefficient = 0.57. Following 12% of the air infusions, there was evidence that a part of the air became detained in vascular sites cranial to the ensonified portion of the SVC. This evidence consisted of the following observations: analog responses were diminished in amplitude; subsequent air injections evoked responses that sometimes were exaggerated; and/or subsequent increases in cardiac output alone, produced spontaneous analog responses characteristic of air emboli. The authors postulate that air similarly may be detained in clinical settings and may explain such phenomenon as persistent precordial Doppler sounds of air emboli after pulmonary artery pressure has returned to normal following symptomatic air embolism and occurrence of air emboli after scalp closure.

Animals↗
PubMed1983

Evaluation of transesophageal Doppler detection of air embolism in dogs.

The authors assessed the use of a cylindrical sensor which transceives (transmits and receives) ultrasound in a 360 degree arc mounted on a standard esophageal stethoscope catheter to detect air embolism in dogs. They used electronic circuitry developed specifically to provide a continuous analog recording of high frequency Doppler energy as well as an audible signal. They found that the esophageal Doppler sensor was easy to position. In 25 of 30 dogs, the system distinguished Doppler sounds of venous air emboli that were present either in the superior vena cava, right atrium, right ventricle, or pulmonary artery from normal cardiovascular sounds. In the remaining five animals, Doppler heart and air emboli sounds were initially of poor quality, but improved with aspiration of air from the esophagus. In another five dogs, arterial air emboli produced by left ventricular injections also were detected. The esophageal sensor was sensitive to both venous and arterial air emboli ranging from 0.05--0.2 ml of air, and the authors consistently detected repeated intravenous injections of air throughout a 5-h time period. Optimal position of the sensor for detection of venous air emboli was at the level of the superior vena cava above its junction with the right atrium. Optimal position to detect arterial air emboli introduced via a left ventricular catheter was at the level of the aortic arch. Tissue analysis of the esophagus revealed no morphologic damage due to the sensor or transmitted energy.

Animals↗
PubMed1980

Limb blood flow. The influence of temperature during halothane-nitrous oxide anesthesia.

Twenty adult patients were examined before anesthesia, during anesthesia, and at the end of surgery to determine the influence of body cooling on limb blood flow during prolonged halothane-nitrous oxide anesthesia. Measurements included temperature, mean arterial pressure, and leg blood flow. Cooling was prevented in ten patients by warmed anesthetic gases. The mean tympanic temperature at end of surgery was 37 degrees C for the warmed (W) and 35 degrees C for the unwarmed (UW) patients, a significant difference. The mean value for leg blood flow was significantly decreased in the UW patients (W = 5.0 vs UW = 3.1 mL/100 cc of tissue/min). These results indicate that body cooling during prolonged inhalation anesthesia was associated with a reduced limb blood flow. Therefore, pulmonary warming may be of potential benefit under similar conditions to help prevent intraoperative vascular complications.

Abdomen↗
PubMed1978

Prevention of post-anaesthesia shivering.

This study involves ventilation of the lungs with warmed humidifed anaesthetic gases during prolonged elective abdominal operations. Tympanic, oesophageal and toe temperatures were compared bewteen twenty warmed and twenty un-warmed patients at various times during operation and recovery. Fifty per cent (10/20) unwarmed patients shivered in the recovery room, while none of the warmed patients shivered. Our data indicate that pulmonary ventilation with warm humidified anaesthetic gases provides heat transfer by the lungs, preventing hypothermia during operation and post -anaesthesia shivering is prevented by maintaining the patient normothermic in both the operating room and the recovery room.

Anesthesia, General↗
PubMed1977

Drug costs.

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Communication↗