PubMed Health⌕ Search

Biomedical subjects

A N Thomas

Publications and source records attributed to A N Thomas.

At least 19 recordsLinked to original sources
PubMed1992

A new technique for two-hand bag valve mask ventilation.

A method of bag valve mask ventilation (BVM) in which the resuscitator compresses the self-inflating bag between the open palm and body was compared with both standard single resuscitator and two-resuscitator BVM ventilation. Eighteen subjects ventilated a modified recording manikin using each method in random order. The tidal volume (VT) was greater with the open palm (mean 684 (SD 182) ml) than standard single resuscitator ventilation (mean 520 (152) ml). The difference was greater in the nine subjects with small hands (mean 196 (103) ml). VT was less than with two-resuscitator ventilation (mean VT 953 (236) ml).

Adult↗
PubMed1992

A nasal CPAP system. Description and comparison with facemask CPAP.

Nasopharyngeal pressures were compared in eight subjects breathing through either a nasal CPAP system or facemask CPAP system at a fresh gas flow of 50, 75 and 100 l.min-1. During nose breathing there was no significant difference in nasopharyngeal pressure between the two systems. During mouth breathing pressures were significantly lower with nasal CPAP. During nose breathing at 75 l.min-1 the mean inspiratory and expiratory pressures in cmH2O (SD) were 3.4 (0.68) and 5.9 (0.55) for nasal CPAP and 3.3 (0.71) and 6.3 (0.73) for facemask CPAP. The respective pressures during mouth breathing were 0.3 (0.73) and 2.9 (1.74) for nasal CPAP and 3.9 (0.73) and 5.8 (0.82) for facemask CPAP.

Adult↗
PubMed1992

Nasal CPAP after coronary artery surgery.

Two groups of 14 patients were compared after coronary artery bypass surgery where the left internal mammary artery had been used as a conduit. One group received nasal continuous positive airway pressure for 1 h, the other group acted as a control. Mean pulmonary shunt fraction was 16.3% before, 12.6% during and 15.7% after continuous positive airways pressure. In the control group the shunt fraction fell from 17.3% to 16.8%. The reduction in shunt fraction was significantly greater with nasal continuous positive airways pressure than in the control group (p = 0.016). There was a significant reduction (p = 0.025) in respiratory rate from 18.3 to 16.7 breath.min-1 during continuous positive airway pressure. Other measured cardiorespiratory variables did not differ significantly between the groups. Visual analogue scores showed no significant difference in chest pain or mask comfort between the groups. The ease of breathing score was, however, significantly better in the continuous positive airways pressure group, 7.5 (SD 1.8) cm and control 5.6 (SD 2.6) cm.

Coronary Artery Bypass↗
PubMed1992

The Laerdal pocket mask: effects of increasing supplementary oxygen flow.

To determine the effect of increasing supplementary oxygen flow during ventilation with the Laerdal pocket mask 24 subjects ventilated a modified recording mannikin for four 90 s periods using the mask with oxygen flows of 5 l, 10 l, 15 l and 20 l.min-1. Oxygen concentration increased and carbon dioxide concentration decreased with increasing oxygen flow. Tidal volume also increased with oxygen flow. The delivered oxygen concentrations were lower than previously reported at all four rates; however, mask function improved with increasing flow up to 20 l.

Adult↗
PubMed1991

Bioimpedance versus thermodilution cardiac output measurement: the Bomed NCCOM3 after coronary bypass surgery.

Values obtained for cardiac output (CO) were compared using thermodilution (TD) with those obtained using bioimpedance (Bi) as measured using the Bomed NCCOM3 (Revision 6) in 28 consecutive patients in the first 24 h after coronary artery bypass surgery (CABS). In 46 paired measurements made in the first 12 h after CABS Bi values for CO were significantly lower than TD values, the limits of agreement between the two methods were also unacceptably large (mean Bi 4.38 (SD 1.40) l/min, mean TD 5.46 (SD 1.19) l/min, limits of agreement -3.05 to +0.89). In 55 paired measurements made after 12 h (all in spontaneously breathing patients) there was no significant difference between the two methods and acceptable limits of agreement, mean Bi 5.69 (SD 1.2) l/min mean TD 5.6 (SD 1.2) l/min, limits of agreement -0.99 to +1.17). The significantly lower BiCO values obtained in the first 12 h after CABS show that BiCO measurement is not consistently reliable in the intensive care setting.

Bias↗
PubMed1991

Non-invasive measurement of cardiac output during induction of anaesthesia and tracheal intubation: thiopentone and propofol compared.

We have investigated the haemodynamic changes in response to induction of anaesthesia and tracheal intubation in patients who received either thiopentone 5 mg kg-1 or propofol 3 mg kg-1 followed by atracurium 0.5 mg kg-1 and fentanyl 1.5 micrograms kg-1. Anaesthesia was maintained with 0.6% enflurane and 50% nitrous oxide in oxygen with assisted ventilation. Cardiac output and heart rate (HR) were monitored continuously with a transthoracic impedence monitor. Mean HR did not change after induction in each group, but increased after tracheal intubation in both groups (P less than 0.01). Mean cardiac index (CI) decreased after induction (P less than 0.05) and decreased further after tracheal intubation in both groups (P less than 0.05). There was no difference between the two groups with respect to changes in CI and HR. Mean arterial pressure (MAP) and systemic vascular resistance (SVR) did not change significantly after induction in the thiopentone group. Both variables increased from preinduction values 1 min after tracheal intubation (P less than 0.001). In contrast, both MAP and SVR decreased after induction in the propofol group (P less than 0.001) and did not differ from preinduction values 1 min after tracheal intubation. MAP and SVR were greater in the thiopentone group compared with the propofol group after induction and tracheal intubation (P less than 0.01).

Adult↗
PubMed1989

Esophageal perforation.

Sixty-nine patients with perforation of the esophagus were treated at the University of California, San Francisco, from 1977 to 1988. The perforation was iatrogenic in 33 (48%) of the patients, spontaneous in 8 (12%), and a result of external trauma in 23 (33%). Clinical findings included chest pain in 36 (52%) of 69 patients, subcutaneous emphysema in 22 (32%) of 59 patients, and pneumomediastinum in 21 (36%) of 59 patients. Esophagograms demonstrated the perforation in 40 (93%) of 43 patients. Treatment delays of more than 24 hours occurred in about half of spontaneous and iatrogenic perforations, but when the perforation was due to external trauma, treatment was delayed infrequently. Operative therapy in 59 (86%) of the patients included primary closure in 44 patients, drainage alone in 9 patients, and Celestin tube placement in 1 patient. Four patients with benign strictures had esophagectomy, and 4 patients with achalasia had Heller myotomy in addition to closure of the perforation. Eight (12%) of the patients were treated nonoperatively. For thoracic perforations, nonoperative treatment was reserved for patients who were diagnosed late but who had minimal evidence of sepsis. Seven (10%) of the patients died. Factors that influenced outcome included cause of perforation, anatomic location, and patient age. Our study shows that a high index of suspicion, aggressive use of esophagography, and individualized treatment are necessary for the best results when treating esophageal perforation.

Adolescent↗
PubMed1989

Renal transplantation and diabetic autonomic neuropathy.

This report describes six episodes of cardiovascular collapse in the perioperative period of a young diabetic woman undergoing general anaesthesia for renal transplantation and a similar episode after a second anaesthetic. She was subsequently found to have an autonomic neuropathy. Recommendations for the management of similar patients are made.

Adult↗
PubMed1989

Acute tracheobronchial injury.

We reviewed our experience with tracheal and bronchial trauma from 1977 to 1988. There were 22 patients with tracheobronchial injuries treated in this period. Seventeen (77%) of the injuries were due to penetrating trauma and five (23%) were due to blunt trauma. Thirteen patients had major associated injuries, including six esophageal injuries. The most common physical findings were tachypnea (13 patients) and subcutaneous emphysema (nine patients). Eight patients presented with airway obstruction. All patients with penetrating cervical tracheal injuries underwent neck exploration and primary repair. All blunt injuries were diagnosed by bronchoscopy. Three patients with blunt injuries were treated with primary repair. Two patients with blunt chest trauma and small bronchial tears were treated nonoperatively with good results. All three deaths (14% mortality rate) were due to associated injuries. We conclude that patients with penetrating tracheobronchial injuries should be managed by surgical exploration and primary repair, although selected patients with blunt injury may be treated nonoperatively.

Adult↗
PubMed1979

Extracorporeal membrane oxygenation in severe acute respiratory failure. A randomized prospective study.

Nine medical centers collaborated in a prospective randomized study to evaluate prolonged extracorporeal membrane oxygenation (ECMO) as a therapy for severe acute respiratory failure (ARF). Ninety adult patients were selected by common criteria of arterial hypoxemia and treated with either conventional mechanical ventilation (48 patients) or mechanical ventilation supplemented with partial venoarterial bypass (42 patients). Four patients in each group survived. The majority of patients suffered acute bacterial or viral pneumonia (57%). All nine patients with pulmonary embolism and six patients with posttraumatic acute respiratory failure died. The majority of patients died of progressive reduction of transpulmonary gas exchange and decreased compliance due to diffuse pulmonary inflammation, necrosis, and fibrosis. We conclude that ECMO can support respiratory gas exchange but did not increase the probability of long-term survival in patients with severe ARF.

Acute Disease↗
PubMed1978

Severe chest trauma. Morbidity implication.

Patients who sustain fracture of either the first or second rib have severe injuries usually involving multiple systems. In comparing 71 patients with first rib fractures and 49 patients with second rib fractures, we found morbidity and mortality to be similar. A multidisciplinary approach to management of these patients is described and vigorous diagnostic and therapeutic measures are warranted to promptly determine the extent of injury and minimize the frequency of missed diagnosis.

Abdominal Injuries↗