PubMed Health⌕ Search

Biomedical subjects

M Layer

Publications and source records attributed to M Layer.

6 recordsLinked to original sources
PubMed2000

Carbon dioxide elimination during high-frequency jet ventilation for rigid bronchoscopy.

Oxygen saturation and carbon dioxide values should be monitored during high-frequency jet ventilation (HFJV). Modern transcutaneous PCO2 (PtcCO2) measurement allows the estimation of ventilation efficiency. We studied how tests of lung function could predict carbon dioxide elimination during HFJV. Lung function tests from 180 adult patients undergoing rigid bronchoscopy were analysed as factors affecting carbon dioxide elimination. The lung function test results showed a significant relationship with the efficiency of carbon dioxide elimination; the greatest impairment of carbon dioxide elimination was found in patients with combined abnormalities of lung function. Further factors associated with difficult carbon dioxide elimination were male gender and elevated body weight. Of the patients investigated, 72% had normal carbon dioxide elimination, whereas in 23% hypercapnia could be avoided only by increasing the driving pressure. The prevalence of abnormal preoperative lung function test results predicts (sensitivity 76%, positive predictive value 27%) impaired carbon dioxide elimination during jet ventilation and rigid bronchoscopy.

Adolescent↗
PubMed2000

Influence of airway-occluding instruments on airway pressure during jet ventilation for rigid bronchoscopy.

We measured changes in airway pressure (Paw) caused by microsurgical instruments introduced into a rigid bronchoscope during high frequency jet ventilation (HFJV). With approval of the institutional Ethics Committee, 10 adults undergoing elective tracheobronchial endoscopy and endosonography during general anaesthesia were investigated. Inflation of an endosonography probe balloon in the left main stem bronchus caused airway obstruction. Pressure measurements proximal and distal to the obstruction were compared after three degrees of obstruction (0%, 50% and 90%) and with two different driving pressure settings. Airway obstruction increased the mean (SD) peak inspiratory pressure (PIP) from 7.5 (2.6) to 9.5 (3.5) mm Hg for 2 atm (P = 0.0008) and from 9.7 (3.7) to 13.0 (5.1) mm Hg for 3 atm (P = 0.0001). Airway obstruction did not alter peripheral PIP (7.2 (4.1) to 7.1 (3.7) mm Hg for 2 atm and 8.8 (4.3) to 9.4 (5.2) mm for 3 atm), but resulted in an end-expiratory pressure (EEP) beyond the narrowing being significantly greater than in the unobstructed airway (2.5 (3.4) to 5.5 (3.7) mm Hg for 2 atm; P = 0.0005) and 3.2 (3.6) to 8.0 (4.3) mm for 3 atm; P < 0.0001). Severe airway narrowing increases inspiratory pressure proximal and expiratory pressure distal to the obstruction in relation to the applied driving pressure. Since the distal EEP never exceeded PIP, even near-total airway obstruction should not cause severe lung distension or barotrauma in subjects with normal lungs.

Aged↗
PubMed1997

[High frequency jet ventilation during tracheal resection in children and infants].

Between 1986 and 1996, 16 infants and children less than 11 years of age (m = 11, f = 5) underwent resections for acquired or congenital tracheobronchial stenoses. During this period, various techniques of total intravenous anaesthesia (TIVA) were employed (midazolam, fentanyl, pancuronium; propofol, fentanyl, pancuronium). During the phase of dividing the airways, high-frequency-jet ventilation (HFJV) into the trachea or the main bronchi by 8-12Fr catheter(s) was applied for 10-75 min with driving pressures between 0.3-1.8 bar, frequencies between 100-200/min, I:E ratio between 1:4-1:1, and FjetO2 1.0. Catheter position was controlled visually, gas exchange was monitored by pulse oximetry and blood gas analysis. There were two incidents of transient hypoxaemia (paO2 less than 60 mmHg), and 4 cases of hypercapnia (paCO2 more than 45 mmHg). No complications due to the HFJV-catheter technique, such as barotrauma or aspiration were seen. All children were kept postoperatively on a ventilator due to swelling of the airway anastomosis. In 5 children ventilator treatment exceeded 7 days, 3 children were discharged tracheostomised. These observations serve to confirm that HFJV is capable of maintaining gas exchange during tracheal resection in infants and children, if the following prerequisites are met: 1. Tracheobronchial pathology suitable for poststenotic placement of jet catheter. 2. No respiratory impairment by parenchymal pathology. 3. Monitoring by continuous visual control of respiratory mechanics, pulse oximetry and blood gas analysis. Cardiopulmonary bypass should be applied if airway pathology precludes safe placement of jet catheters, or in the presence of parenchymal respiratory failure.

Anesthesia, General↗
PubMed1990

Clonidine as a sedative adjunct in intensive care.

A 63-year-old man underwent distal oesophagectomy and proximal gastrectomy. Postoperatively, controlled ventilation was necessary for 53 days because of anastomotic leakage. Multiple sedative regimens proved to be inadequate. By contrast, a fentanyl-midazolam combination with continuous supplementation of clonidine 0.014 micrograms kg-1 min-1 (1.44 mg 70 kg-1 24 h-1) was very effective in terms of sedation and pain relief. During combined fentanyl-midazolam and clonidine infusion, cardiovascular depression gradually developed over several days necessitating the institution of a dobutamine infusion (dose: 8-12 micrograms kg-1 min-1). Four attempts of abrupt clonidine withdrawal were followed by sympathetic overshoot reactions consisting of tachycardia, hypertension, agitation, and sweating. Discontinuation of clonidine was finally possible after a 12-day weaning period.

Clonidine↗
PubMed1990

[Muscle relaxants for kidney transplantation. A comparison between vecuronium and atracurium].

A total of 26 patients with end-stage renal failure were assigned randomly to receive either atracurium (A) or vecuronium (V) for intra-operative relaxation during kidney transplantation. Following the induction of balanced anesthesia an initial bolus dose of A 0,5 mg/kg body weight (BW) or V 0,1 mg/kg BW was administered. Relaxation was maintained by repeated doses of A 0,1 mg/kg BW or V 0,02 mg/kg BW whenever the twitch height (T1) recovered to 20% of the control value. Neuromuscular function was monitored throughout using the train-of-four twitch technique. There were no significant differences in time of onset (A: 219 +/- 87 s, V: 206 +/- 70 s), initial clinical duration (T1 = 0% to T1 = 20%; A: 39 +/- 12 min, V 39 +/- 8 min) or recovery index (A: 19 +/- 6 min, V: 22 +/- 7 min). The clinical duration (T1 = 20% to T1 = 20%) was significantly different for A, with 27 +/- 9 min than for V, with 32 +/- 7 min (P less than 0.05, Wilcoxon-Mann-Whitney U-Test; all values means +/- standard deviation). Reversal of relaxants was mandatory according to electromyographic and clinical criteria in only one patient in the A group but in 5 in the V group (P less than 0.05, Fisher's exact test). We conclude that A might be more suitable in patients with renal insufficiency and that monitoring of neuromuscular transmission is highly valuable in this risk group.

Adult↗