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Biomedical subjects

F M Midgley

Publications and source records attributed to F M Midgley.

At least 19 recordsLinked to original sources
PubMed2000

Comparison of three techniques for internal jugular vein cannulation in infants.

Central venous cannulation allows accurate monitoring of right atrial pressure and infusion of drugs during the anaesthetic management of infants undergoing cardiopulmonary bypass. In this prospective, randomized study, we compared the success and speed of cannulation of the internal jugular vein in 45 infants weighing less than 10 kg using three modes of identification: auditory signals from internal ultrasound (SmartNeedle, SM), external ultrasound imaging (Imaging Method, IM) and the traditional palpation of the carotid pulsation and other landmarks (Landmarks Method, LM). The cannulation time, number of attempts with LM and SM techniques were greater than those with IM technique. The incidence of carotid artery puncture and the success rate were not significantly different among the three groups. In infants, a method based on visual ultrasound identification (IM) of the internal jugular vein is more precise and efficient than methods based on auditory (SM) and tactile perception (LM).

Cardiac Surgical Procedures↗
PubMed1999

Ultrasound-guided internal jugular venous cannulation in infants: a prospective comparison with the traditional palpation method.

BACKGROUND: Percutaneous cannulation of the internal jugular vein in infants is technically more difficult and carries a higher risk of carotid artery puncture than in older children and adults. In this prospective study, the authors tested their hypothesis that using an ultrasound scanner would increase the success of internal jugular cannulation and decrease the incidence of carotid artery puncture in infants. METHODS: After approval from the institutional review board and receipt of written informed parental consent, 95 infants scheduled for cardiac surgery were randomized prospectively into two groups. In the landmarks group, the patients' internal jugular veins were cannulated using the traditional method of palpation of carotid pulsation and identification of other anatomic landmarks. In the ultrasound group, cannulation was guided using an ultrasound scanner image. The cannulation time, number of attempts, success rate, and incidence of complications were compared for the two groups. RESULTS: There were no significant differences between the two groups with regard to weight, age, and American Society of Anesthesiologists physical status classification. The success rate was 100% in the ultrasound group, with no carotid artery punctures, and 77% in the landmarks group, with a 25% incidence of carotid artery punctures. Both differences were significant (P > 0.0004). The cannulation time was less, the number of attempts was fewer, and the failure rate was significantly lower in the ultrasound group than in the landmark group. CONCLUSION: Ultrasonographic localization of the internal jugular vein was superior to the landmarks technique in terms of overall success, speed, and decreased incidence of carotid artery puncture.

Carotid Artery Injuries↗
PubMed1997

Cervical aortic arch with aneurysm formation.

Two pediatric cases of cervical aortic arch with aneurysm formation are reported. Only female patients with cervical aortic arch have developed aneurysms, which may influence risk counseling of such patients.

Aorta, Thoracic↗
PubMed1996

Traumatic thoracic aortic rupture in the pediatric patient.

BACKGROUND: Traumatic thoracic aortic rupture is a rare injury in the pediatric patient. Experiences with thoracic aortic rupture in patients less than 17 years of age are needed to help identify factors that can influence injury occurrence, diagnosis, management, and outcome. METHODS: Between July 1989 and December 1995, 6 children were treated operatively for thoracic aortic rupture from blunt trauma at a level I pediatric trauma center. The average age was 13.2 years (range, 8 to 16 years). There were 4 females and 2 males. There were 5 motor vehicle accidents and 1 bicycle accident. Aortic injury was suspected based on the mechanism of injury and abnormal chest roentgenogram results, and was confirmed by aortography (3 cases) or chest computed tomography (2) and transesophageal echocardiography (3). Life-threatening central nervous system or gastrointestinal injuries were evaluated or treated first. Operative repair of the thoracic aorta was performed by cardiopulmonary bypass (2 patients) and clamp and sew technique (4). RESULTS: Aortic ruptures were complete transections at the ligamentum arteriosum in 5 of 6 (83%); the other case was a cervical arch pseudoaneurysm. Associated injuries included pulmonary contusion (100%), pelvic/long bone fractures (50%), visceral laceration/perforation (50%), central nervous system (33%), paraplegia (17%), and myocardial contusion (17%). There were no rib fractures. Four of 5 patients (80%) were not wearing seat belts, and 2 of these were ejected. The average time from injury to the operating room was 17.6 hours (range, 5 to 48 hours); the time from diagnosis to the operating room exceeded 5 hours with aortography and was less than 3 hours with chest computed tomography and transesophageal echocardiography. Each diagnostic modality accurately identified an aortic injury. The average time for cardiopulmonary bypass and for clamp and sew was 52 minutes (range, 49 to 55 minutes) and 34 minutes (range, 16 to 45 minutes), respectively. One patient with preoperative paraplegia regained partial function; there were no other patients with paraplegia. There were no deaths. All patients are alive 2 months to 7 years after repair. CONCLUSIONS: The multiply injured child with severe blunt trauma and an abnormal chest roentgenogram requires a search for aortic injury. We believe the most effective algorithm to follow for the diagnosis of traumatic thoracic aortic rupture in the child involves selective performance of chest computed tomography and transesophageal echocardiography. Our experience suggests that the mechanism of injury, the duration to diagnosis of an aortic injury, and failure to use seat belts may contribute to morbidity. A high index of suspicion and a systematic approach to the diagnosis and to the management strategy for injuries to the thoracic aorta can contribute to a good outcome in those few children who survive the injury.

Adolescent↗
PubMed1994

Mediastinal perigraft seroma: CT and MR imaging.

We report a patient who developed a perigraft seroma after a modified Blalock-Taussig procedure in which a polytetrafluoroethylene (Gore-tex) graft was used. Computed tomography and magnetic resonance were instrumental in the evaluation of this seroma.

Blood Vessel Prosthesis↗
PubMed1993

Routine use of transesophageal echocardiography and color flow imaging in the evaluation and treatment of children with congenital heart disease.

We reviewed our experience with transesophageal echocardiography (TEE) and color flow imaging in 157 consecutive patients with known or suspected heart disease to ascertain the impact of this technology on patient care. TEE was performed for diagnostic purposes (22/157), during interventional cardiac catheterizations (13/157), and during operative procedures (122/157). Diagnostic studies were performed after transthoracic echocardiography (TTE) in 21 of 22 patients. TEE was performed because TTE was inconclusive (15/21) or failed to provide sufficient detail of an abnormality (6/21). TEE detected an abnormality in 6 of 15 inconclusive TTEs. TEE was helpful during interventional cardiac catheterizations, particularly during umbrella closure of septal defects and in patients with complex venous and atrial anatomy undergoing transseptal puncture. TEE studies performed before cardiac operations significantly changed the diagnosis in only 5 of 122 (4%) patients, but the information changed the surgical approach in 4 of 5 of these patients. Postoperative TEE assessment more frequently changed care and resulted in further surgical management in 9 of 122 (7%) or a change in medical management in 6 of 122 (5%) patients. TEE was discontinued because of complications before studies were completed in only 4 of 157 (3%) patients. TEE and color flow imaging is a useful adjunct to care of children with known or suspected congenital heart disease.

Adolescent↗
PubMed1992

Circulating endotoxin and tumor necrosis factor during pediatric cardiac surgery.

OBJECTIVES: To study the hypothesis that endotoxin and tumor necrosis factor-alpha (TNF) are released into the circulation during the perioperative period in children undergoing open-heart surgery, and to assess the possible role of these factors in postoperative morbidity. DESIGN: Prospective study. SETTING: Operating room and ICU of a children's hospital. PATIENTS: Twenty-four consecutive patients undergoing open-heart surgery for repair of congenital heart disease. METHODS: Endotoxin and TNF concentrations were measured in blood samples withdrawn from patients at predetermined time points in the perioperative period. These concentrations were also measured in samples from all fluids and drugs administered to patients. Clinical variables were measured throughout the perioperative period, and the Pediatric Risk of Mortality score was calculated daily. RESULTS: All of the preoperative control samples were negative for endotoxin and TNF. Endotoxin or TNF was detected in the blood of 21 (88%) of 24 patients during or after surgery. Endotoxin (ranging in concentrations from 0.32 to 438 pg/mL) was detected in the blood of 16 (67%) of the 24 patients. The majority of the samples positive for endotoxin were withdrawn during cardiopulmonary bypass and were associated with positive samples from the pump, from cardiotomy suction specimens, and from autotransfused blood. Blood cultures of all patients, except one, were negative for bacterial growth. TNF (ranging in concentrations from 3 to 132 U/mL) was detected in the blood of nine (37%) of the 24 patients. Patients positive for TNF had significantly (p less than .05) lower mean central venous pressures at 20 hrs after surgery and higher mean heart rates postoperatively compared with patients negative for TNF. No differences in other indicators of perioperative morbidity and intraoperative conditions were found, when the groups positive for endotoxin or TNF were compared with the groups negative for endotoxin or TNF, respectively. CONCLUSIONS: Endotoxin and TNF are released into the circulation during and after pediatric open-heart surgery. TNF release may be related to some of the hemodynamic changes observed after open-heart surgery.

Child↗
PubMed1991

Immune dysfunction in children after corrective surgery for congenital heart disease.

OBJECTIVE: To study the effect of open- and closed-heart surgery on the immune status of infants and children. DESIGN: Prospective study. Data collected before anesthesia and surgery and 2 and 24 hrs after surgery. SETTING: Operating room and pediatric ICU in a children's hospital. PATIENTS: Children undergoing surgery for correction of congenital heart disease (age 3 months to 12 yrs). A total of 31 patients were studied (open-heart surgery, n = 25; closed-heart surgery, n = 6). MEASUREMENTS AND MAIN RESULTS: Increased neutrophil counts and lymphopenia were observed after both open- and closed-heart surgery. Serum levels of the complement components C3 and C4 were depressed after open-heart surgery, but not after closed procedures. The percentage of T3+ and T4+ lymphocytes, proliferative responses of the lymphocytes and serum immunoglobulin (Ig)G and IgM were decreased from preoperative levels after open-heart surgery. The percentage of T8+ lymphocytes and serum IgA levels did not change. Intraoperative variables and postoperative severity of illness (Pediatric Risk of Mortality score) did not correlate with immune suppression. CONCLUSIONS: The immune system is affected after pediatric cardiac surgery, particularly after open-heart surgery.

Cardiac Surgical Procedures↗
PubMed1989

Doppler echocardiographic evaluation of tilting-disc prosthetic heart valves in children.

To determine the Doppler characteristics of tilting-disc prosthetic heart valves in children, 22 children with mitral prostheses were studied 8 +/- 2 months after surgery, and 10 children with aortic prostheses were studied 37 +/- 26 months after surgery. All valves were thought to be functioning normally by clinical examination. Valve competence was interrogated and peak and mean velocities were measured by standard pulsed wave, continuous wave and color Doppler techniques. Prosthetic valve area was calculated and compared to the known valve area. Mild prosthetic valve regurgitation was present in 8 of 22 mitral and 7 of 10 aortic prostheses. For mitral prostheses, peak velocity was 192 +/- 41 cm/s, mean velocity was 118 +/- 37 cm/s and mean gradient was 7 +/- 4 mm Hg. For aortic prostheses, peak velocity was 287 +/- 88 cm/s, mean velocity was 197 +/- 59 cm/s, peak gradient was 36 +/- 21 mm Hg and mean gradient was 19 +/- 11 mm Hg. Prosthetic mitral valve area, calculated by the pressure half-time and modified Gorlin methods, correlated well with the known valve area (r = 0.89, standard error of the estimate = 0.29 and r = 0.95, standard error of the estimate = 0.21, respectively). Prosthetic aortic valve area, calculated by the modified Gorlin method, correlated well with the known valve area (r = 0.89, standard error of the estimate = 0.18). Residual valvular abnormalities are common after prosthetic valve insertion in children. Doppler estimates of prosthetic valve area correlate well with the known valve area but have a large standard error of the estimate.

Aortic Valve↗
PubMed1989

Long-term results after surgical repair of incomplete endocardial cushion defects.

Since 1964, 56 children (mean age, 6.7 years) underwent repair of incomplete endocardial cushion defects. Forty patients had isolated ostium primum defects. Additional congenital defects were present in 17 patients (30%). All patients underwent patch closure of the ostium primum defect and 47 of 56 patients (84%) underwent mitral valvuloplasty. Hospital mortality was 1.8% (one death). Arrhythmias developed in 7 other patients in the early postoperative period, of which six were transient and resolved completely. One patient required early pacemaker placement for complete heart block. Cumulative follow-up was 378 patient-years. There were three late deaths (5.7%), and additional operations were required in 12 patients (22.6%). Seven of these 12 patients required mitral valve replacement for severe mitral regurgitation. The mean interval between initial repair and mitral valve replacement was 4.2 years, with only three valves needing replacement within 12 months. There was a significant correlation between the severity of mitral regurgitation before initial repair and subsequent need for mitral valve replacement. Late onset atrial arrhythmias have developed in 6 patients. Current functional status has been evaluated in 50 of 52 surviving patients and 88.5% are in NYHA class I, with the remainder in class II.

Adolescent↗
PubMed1986

High-frequency ventilation versus conventional ventilation in dogs with right ventricular dysfunction.

A randomized crossover protocol was used to compare conventional mechanical ventilation (CMV) and high-frequency ventilation (HFV) in mongrel dogs experiencing right ventricular dysfunction after right ventriculotomy. When inspired oxygen, pH, PCO2, core temperature, and preload were held constant, cardiac output increased significantly (p less than .05) from 1.16 +/- 0.24 to 1.38 +/- 0.25 L/min and pulmonary vascular resistance decreased significantly (p less than .05) from 734 +/- 257 to 554 +/- 169 dyne X sec/cm5 during HFV relative to CMV. We also noted a significant (p less than .05) increase in mean arterial pressure from 116 +/- 27 to 124 +/- 23 mm Hg and a significant (p less than .05) increase in left ventricular stroke work from 10.2 +/- 3.5 to 12.3 +/- 2.6 g X m during HFV. During the inspiratory phase of CMV there were increases in CVP, pulmonary artery pressure, and systemic arterial pressure, and decreases in pulmonary artery flow which did not occur during HFV. HFV may be preferable to CMV in the presence of right ventricular dysfunction.

Animals↗
PubMed1986

Costs and results of cardiac operations in infants less than 4 months old. Are they worthwhile?

From 1979 through 1983, 328 of 1,388 pediatric cardiac operations involved patients undergoing their first procedure at less than 4 months of age. Of these, 220 patients had 265 nonductal procedures, and their case histories are reviewed for results and total hospital cost. Initial operative mortality was 20% (43 patients). Infants with lower operative age and operative weight tended to have closed procedures. Mortality and cure were not related to gestational age, birth weight, age at operation, number of operations, or type of operation. Lower operative weight was associated with a greater mortality. Evaluated survivors (142 patients) were followed for a mean of 24 months. Fifteen percent (33 patients) died during follow-up. Of survivors, 80% (114 patients) had optimized general health; a subset of 29% had normal cardiac function, and 17% were cured. Lower birth weight was associated with curable lesions and normalcy (p less than 0.04). Longer preoperative hospital stay and lower weight at operation were associated with higher hospital cost (p less than 0.05). Hospital cost was not related to type of operation, gestational age, birth weight, age at operation, mortality, cure, or normalcy. Acquired neurologic dysfunction and long-term disability were uncommon. The mean hospital cost for surviving infants was +80,000 (1984 dollars). Effective hospital cost per survivor was +110,000. Mortality, cure, and normal function after cardiac operations in infants less than 4 months of age were not related to gestational age, birth weight, or age at operation. Mortality was higher in patients with a lower weight at operation. Separation into distinct fiscal cost groups is not reasonable in this series. Because most survivors are in normal or optimized cardiac health, intensive cardiovascular care in this population is justified.

Age Factors↗
PubMed1985

Anticoagulation therapy in children with mechanical prosthetic cardiac valves.

From 1980 through 1984, 28 children younger than 19 years (mean 7.9) underwent cardiac valve replacement with 30 mechanical prostheses. Patients were followed for a total of 471 months (mean 15.7) and received either warfarin (mean 0.16 mg/kg/day) or acetylsalicylic acid and dipyridamole (mean 6.1 and 1.9 mg/kg/day, respectively) as thromboembolism prophylaxis. The frequency and incidence of thromboembolism and hemorrhage were compared. Warfarin-treated patients were at increased risk of hemorrhage (5 of 20 [25%], or 22 per 100 patient-years, vs 0 of 10 [0%], or 0 per 100 patient-years, p less than 0.05). Three of the 5 hemorrhagic episodes were mild, and in no case was hemorrhage life-threatening. Patients who did not receive warfarin had a greater risk of thromboembolism (2 of 10 [20%], or 12 per 100 patient-years, vs 0 of 20 [0%], or 0 per 100 patient-years, p less than 0.05). Both episodes of thromboembolism were life-threatening and necessitated emergency valve replacement. Although warfarin is associated with greater risk of hemorrhage than is acetylsalicylic acid and dipyridamole, warfarin is better than antiplatelet drugs in thromboembolism prophylaxis and is indicated for anticoagulation therapy in children with mechanical cardiac prostheses.

Aspirin↗