Lung mechanics during upper abdominal surgery

Functional residual capacity (FRC) and breath-by-breath compliance of the respiratory system (Crs) were studied after induction of anaesthesia, after insertion of retractors and after wound closure in patients undergoing upper abdominal surgery via a subcostal (n = 8) or a midline (n = 8) incision. After anaesthesia induction the mean FRC was 1.6 +/- 0.3 l. In the subcostal incision group FRC did not change between the studied stages, but Crs fell after retractor placement from 51 +/- 3 to 43 +/- 5 ml/cmH2O (p less than 0.01). In the midline incision group FRC rose by 21% (p less than 0.01) when the retractors were inserted, but regained outset level after wound closure. Crs in this group did not change significantly after retraction, but after closure of the wound it fell to 44 +/- 6 ml/cmH2O, i.e. less (p less than 0.05) than the outset value (52.6 ml/cmH2O). FRC thus did not decrease in either group, but Crs fell by about 15%. The authors conclude that the known difference in postoperative pulmonary complications between midline vs. subcostal incisions is not caused by the studied intraoperative events.     

Propofol or halothane anaesthesia for children with asthma: effects on respiratory mechanics

Propofol may cause histamine release and alter airway tone and reactivity. Although its use has been reported to be safe in asthmatics, there is a lack of information on its effect on lung function in children with asthma. We measured respiratory mechanics after i.v. or inhalation anaesthesia in 60 children, aged 2-12 yr, with or without asthma. Anaesthesia was induced with propofol 3 mg kg-1, fentanyl 1 microgram kg-1 and atracurium 0.5 mg kg-1 and maintained with an infusion of propofol 10 mg kg-1h-1 and 50% nitrous oxide in oxygen. Halothane was administered subsequently at a concentration of 1 MAC. Respiratory mechanics were measured by applying a single- compartment model using multi-linear regression analysis to calculate dynamic compliance (Crs,dyn) and respiratory system resistance (Rrs), based on: Pao = V/Crs,dyn + V Rrs + PA,EE, where Pao = airway opening pressure, PA,EE = alveolar pressure, V = volume and V = flow. The two groups were comparable in age, weight and ventilation variables (tidal volume and peak pressure). Respiratory mechanics during propofol anaesthesia were comparable in normal and asthmatic children (Rrs = 20.5 X 10(-4) (SD 5.2 X 10(-4)) vs 21.5 X 10(-4) (5.7 X 10(-4)) kPa ml- 1 S-1 (ns) and Crs,dyn = 247.5 (76.51 vs 235.1 (63.8) ml kPa-1 (ns)). Halothane produced a minimal decrease in Rrs and a minimal increase in tidal volume in both groups without changes in Crs,dyn. In conclusion, respiratory mechanics were comparable after propofol anaesthesia in both children with and without asthma. Changes in Rrs after halothane administration were not clinically relevant.      

Changes in lung volume and lung-thorax compliance during cardiac surgery in children 11 days to 4 years of age

To examine the effects of cardiac surgery and cardiopulmonary bypass (CPB) on the lung, functional residual capacity (FRC) and lung-thorax compliance were measured at four stages during open heart surgery in 15 children. The patients were anesthetized with fentanyl/droperidol and N2O/O2, paralyzed, and ventilated with volume-controlled mechanical ventilation at 20-30 breaths/min. FRC was measured by tracer gas washout. Static lung-thorax compliance (CLT) was calculated as tidal volume divided by the airway pressure difference between the end of the postinspiratory pause and the end of the expiration, and also from the increase in FRC caused by adding 5 cmH2O of PEEP (CLT[FRC]). Before skin incision, both FRC and compliance were closely correlated with weight and length. During this stage, FRC was 21 +/- 5 ml/kg, CLT 0.90 +/- 0.21, and CLT(FRC) 1.28 +/- 0.35 ml X cmH2O-1 X kg-1 X PEEP 5 increased FRC by 34 +/- 9%. In patients with intact pleural cavities throughout the operation (n = 10), FRC increased by 4 +/- 2 ml/kg when the sternum was retracted (P less than 0.01). During CPB, FRC decreased by 4 +/- 3 ml/kg (P less than 0.01), and FRC at the end of surgery was 5 +/- 4 ml/kg less than before skin incision (P less than 0.01). In these ten children, there was a 13% and 6% decrease in mean CLT and CLT(FRC), respectively, during the operation (P less than 0.05) and mean CLT(FRC) was at least 40% greater than CLT during all four stages (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuromuscular blockade for rapid tracheal intubation in children: comparison of succinylcholine and pancuronium

To compare the effectiveness of succinylcholine and pancuronium for rapid intubation in children, 49 healthy children ages two to eight years were studied. After induction of anaesthesia with thiopentone and atropine, and administration of droperidol, fentanyl, nitrous oxide, and oxygen, each child received one of the following muscle relaxants: succinylcholine 1.5 mg X kg-1 (n = 12), succinylcholine 1.0 mg X kg-1 (n = 13), pancuronium 0.15 mg X kg-1 (n = 11), or pancuronium 0.10 mg X kg-1 (n = 13). The force of thumb adduction was measured by stimulating the ulnar nerve with repetitive supramaximal single twitches (0.15 Hz). The time to 95 per cent twitch depression (mean +/- S.D.) was most rapid with succinylcholine 1.5 mg X kg-1 (40.8 +/- 3.0 seconds) and succinylcholine 1.0 mg X kg-1 (51.8 +/- 14.0 seconds), slowest with pancuronium 0.10 mg X kg-1 (150.9 +/- 38.0 seconds), and intermediate with pancuronium 0.15 mg X kg-1 (80.3 +/- 21.8 seconds) (p less than 0.005). The intubating conditions were excellent in 100% of the children who received succinylcholine 1.5 and 1.0 mg X kg-1, and pancuronium 0.15 mg X kg-1, but were excellent in only 69 per cent of those who received pancuronium 0.10 mg X kg-1. We conclude that succinylcholine 1.5 mg X kg-1 produces the most rapid onset of excellent intubating conditions in children. In children in whom succinylcholine is contra-indicated, pancuronium 0.15 mg X kg-1 provides excellent intubating conditions within 80 seconds.     

Respiratory dead space under anaesthesia in patients with mitral stenosis.

Physiological deadspace (VDphys) and arterial to end-tidal carbon dioxide tension difference [P(a-E)CO2] were calculated under anaesthesia in 27 patients with mitral stenosis planned for close mitral commissurotomy and in 15 healthy individuals for elective non-thoracic surgical procedures. A square wave inspiratory flow pattern and an end-inspiratory pause (25% and 10% of cycle time respectively) were given with a SERVO 900B ventilator used at respiratory rate of approximately 16 per min. An infra-red CO2 analyser was used to measure CO2 production and end-tidal CO2 concentration. Measurements were made prior to the start of the surgery after a minimum of 10 min of stable ventilation to avoid the effect of surgery. Patients with multiple stenosis had significantly higher VDphys (4.28 +/- 1.02 ml kg-1 as compared to 2.10 +/- 0.52 ml kg-1 in controls, P less than 0.001), higher P(a-E)CO2 [0.43 +/- 0.51 kPa as compared to -0.02 +/- 0.23 kPa, P less than 0.01] and lower respiratory system compliance (Crs). Péco2 was positively correlated with PaCO2 in both groups (P less than 0.01). PaO2 was lower in mitral stenosis patients and P(A-a)O2 negatively correlated to Crs (P less than 0.01).     

Pulmonary effects of body position, PEEP, and surfactant depletion in dogs

The influence of position (sphinx, lateral, supine), surfactant depletion, and different positive end-expiratory pressure (PEEP) on functional residual capacity (FRC), series dead space (VdS) and compliance of the respiratory system (Crs) were evaluated in five dogs. Ventilation homogeneity as measured by an index (multiple breath alveolar mixing efficiency), oxygenation, and cardiovascular hemodynamics were additionally examined. The dogs were anesthetized with halothane, paralyzed, and mechanically ventilated. FRC and VdS were found to be notably large in dogs, 45 +/- 8 ml/kg and 6 +/- 1 ml/kg, respectively. FRC and ventilation homogeneity were improved in the sphinx position (prone position with upright head). Surfactant depletion by lung lavage with 37 degrees C saline caused an immediate and stable decrease in FRC, Crs, and oxygenation (P less than 0.05, respectively) for about 5 h without marked effects on the circulatory system. FRC and VdS increased with increasing PEEP. At the highest PEEP, 10 cmH2O (1 kPa), Crs decreased (P less than 0.05) and ventilation became more uneven, indicating alveolar overdistension.     

Prostaglandin F2 alpha improves oxygen tension and reduces venous admixture during one-lung ventilation in anesthetized paralyzed dogs

The authors investigated the effect of prostaglandin F2 alpha infused into the pulmonary artery of an acutely atelectatic lung in dogs. Seven dogs were anesthetized with piritramid and pentobarbital and intubated with a Kottmeier canine endobronchial tube. Cardiac output, pulmonary arterial, capillary wedge, and systemic arterial pressure were measured via indwelling catheters. Ventilating both lungs with 66% O2, PaO2 was 327 +/- 15 mmHg (mean +/- SD) and venous admixture (Qsp/Qt) was 11 +/- 3%. One-lung atelectasis reduced PaO2 to 91 +/- 12 mmHg and increased Qsp/Qt to 40 +/- 4%. Prostaglandin F2 alpha in doses of 0.4, 0.6, 1.2, and 1.8 micrograms X kg-1 X min-1 was infused into the pulmonary artery of the atelectatic lung through a second pulmonary artery catheter. Up to a dose of 1.2 micrograms X kg-1 X min-1 there was a dose-dependent reduction in Qsp/Qt to a minimum of 25 +/- 4% and an increase in PaO2 to 168 +/- 25 mmHg, which could be explained by enhanced pulmonary vasoconstriction in the atelectatic lung with increased blood flow diversion toward the ventilated lung. Infusion of 1.8 micrograms X kg-1 X min-1 decreased PaO2 to 156 +/- 32 mmHg and increased Qsp/Qt to 32 +/- 9%. Increased systemic effects of prostaglandin F2 alpha were observed and presumably were related to saturation of prostaglandin-dehydrogenase leading to vasoconstriction in both lungs and thus reduced blood flow diversion toward the ventilated lung.     

Extravascular lung water and acute respiratory distress syndrome--oxygenation and outcome.

We studied eleven consecutive patients to assess the influence of extravascular lung water on clinical outcome. All patients were mechanically ventilated using a standardized protocol. Inspired oxygen concentration was adjusted to an initial target PaO2 of greater than 8.0 kPa (60.8 mmHg). All patients received inhaled nitric oxide (NO) at a concentration of 20 ppm. Extravascular lung water index (EVLWI) was measured by a dual indicator technique (COLD Z-021 monitoring system, Pulsion, Munich, Germany). Patients were managed with fluids and inotropes according to a standard protocol. Median age was 45 (range 27-60) years, mean APACHE II score on admission 31 (range 17-36), duration of mechanical ventilation 15 (range 6-28) days, mean admission Murray lung injury score 2.5 (range 2-3) and admission EVLWI 20.8 (range 8.7 to 54.7) ml.kg-1. The only variables independently predictive of PaO2/FiO2 ratio were serum albumin (B = 1.7 +/- 1.61) and EVLWI (B = -2.1 +/- 0.47), r2 = 0.33, P < 0.0001. In severe ARDS, (PaO2/FiO2 < 150 mmHg), mean EVLWI was 24.4 (22.4 to 26.4, 95% confidence intervals) ml.kg-1 compared with 15.1 (12.2 to 18.0) ml.kg-1 during moderate ARDS (P < 0.001). Serum albumin likewise differed, 29.4 (27.6 to 31.2) vs 35.1 (31.8 to 38.4) g.l-1, P < 0.005. PAOP was higher during periods of poor oxygenation, 12.7 (11.9 to 13.5) vs 9.3 (7.9 to 10.7) mmHg, P < 0.001. The four survivors had greater initial EVLWI than non-survivors, 31 (24.1 to 37.9) vs 20.7 (16.0 to 25.4) ml.kg-1, P = 0.034 and showed a greater reduction in lung water, 15.2 (9.3 to 21.1) vs 5.4 (2.1 to 8.7) ml.kg-1, P = 0.013.     

Effects of dose and concentration of rectal methohexitone for induction of anaesthesia in children

To investigate the effect of dose and concentration of rectal methohexitone for induction of anaesthesia, 60 children (ASA physical status 1 or 2) undergoing outpatient surgery were studied. Each child was randomly assigned to receive one of three rectal solutions (each containing atropine 0.02 mg X kg-1): Group A - ten per cent methohexitone, 25 mg X kg-1 (n = 20); Group B - ten per cent methohexitone, 15 mg X kg-1 (n = 20); or Group C - one per cent methohexitone, 15 mg X kg-1 (n = 20). After induction of anaesthesia, or a maximum period of 20 minutes following rectal administration of methohexitone, halothane, nitrous oxide, and oxygen were administered by mask. The time to induction of anaesthesia, complications, postanaesthetic recovery scores, and recovery time did not differ significantly among the three groups. The incidence of failed inductions did not differ significantly between Group A (zero per cent) and Group C (ten per cent) but both were significantly less than Group B (45 per cent) (p less than 0.05). Heart rate increased significantly between 10 and 30 minutes after rectal administration of methohexitone and atropine. The authors conclude that ten per cent rectal methohexitone 25 mg X kg-1 and one per cent rectal methohexitone 15 mg X kg-1 are equally effective for induction of anaesthesia in children and both are significantly more effective than ten per cent methohexitone 15 mg X kg-1.     

Comparison of metaproterenol, isoetharine and salbutamol in the relief of methacholine-induced bronchospasm in dogs

We evaluated cardiovascular effects and effectiveness of isoetharine, metaproterenol and salbutamol, when administered intratracheally to relieve methacholine-induced bronchospasm in dogs anaesthetized with 50 per cent nitrous oxide, oxygen, halothane and mechanically ventilated. Methacholine 2 micrograms X kg-1 X hour-1 was administrated first followed by halothane (1 MAC) for 30 minutes (control), then metaproterenol, isoetharine or salbutamol. Metaproterenol (15 mg) significantly decreased transpulmonary pressure to 20.1 +/- 0.5 (SE) from 22.5 +/- 1.15 cmH2O (p less than 0.025) after three min and to 15 +/- 0.5 cmH2O (p less than 0.005) after 90 min. Isoetharine (2.5 mg) decreased transpulmonary pressure after five min to 22.1 +/- 1 from 24.5 +/- 1.5 cmH2O (p less than 0.05), and to 21.75 +/- 0.55 mmH2O after 90 min. Salbutamol 25 micrograms X kg-1 decreased transpulmonary pressure to 20.7 +/- 0.75 from 24.25 +/- 1.28 after three min and to 16 +/- .5 after 90 min. The peak effects on airway pressure occurred at 15 min for metaproterenol, 25 min for salbutamol and 20 min for isoetharine. Pulmonary vascular resistance was not significantly changed during halothane anaesthesia alone but decreased significantly after metaproterenol and isoetharine infusion. Heart rate increased ten per cent after metaproterenol, three per cent after isoetharine, and five per cent after salbutamol. No arrhythmias occurred in any group. Cardiac output increased significantly to 3.25 +/- 0.2 from 1.5 +/- 0.17 L X min-1 (p less than 0.025) after metaproterenol to 3.2 +/- .025 from 1.45 +/- .009 after salbutamol and was unchanged after isoetharine. Metaproterenol and salbutamol in the presence of 1 MAC halothane anaesthesia relieved methacholine-induced bronchospasm more rapidly than did isoetharine. The onset of effect was 3 +/- 0.05 min for metaproterenol and salbutamol and 5 +/- 0.01 min for isoetharine. The effect lasted 210 +/- 10.5 min for metaproterenol, 170 +/- 12.5 min for salbutamol and 90 +/- 4.75 min for isoetharine.     

Metabolic Correlates in Infants and Children During Anaesthesia and Surgery

In 58 infants and children with body weights between 2.8 and 20.5 kg carbon dioxide production (VCO2 ml min-1) was measured during halothane anaesthesia for minor surgical procedures. In 22 cases measurements were made during both spontaneous and controlled ventilation during the same operation. A non-rebreathing circuit was used. Expired ventilation volume was measured with a dry gas meter and expired gas collected during 3-5 min in a Douglas bag. The carbon dioxide fraction of exhaled gas was determined with a sampling Gould capnograph. A respiratory quotient (RQ) of 0.8 was used to calculate oxygen consumption (VO2 ml min-1). During spontaneous breathing, regression analysis of the relationship between VCO2 and kg and between VO2 and kg showed high intercepts while corresponding relations to kg3/4 revealed an almost direct proportionality. Thus, VCO2 and VO2 ought to be related to body weight in kg3/4 in spontaneously breathing children. The mean value (+/- 1 s.d.) for VCO2 was 11.4 +/- 3.1 ml kg-3/4 and for VO2 14.2 +/- 3.9 ml kg-3/4. During controlled ventilation, the relationship between kg b.w. showed for VCO2 as well as for VO2 an almost direct proportionality with a mean value (+/- 1 s.d.) for VCO2 of 6.3 +/- 1.6 ml min-1 kg-1 and for VO2 of 7.8 +/- 2.0 ml min-1 kg-1. Prediction of VO2 for infants and children of this size could be based upon 14 X kg3/4 during halothane anaesthesia and surgery.     

Baroreflex activity in carotid endarterectomy during general anesthesia

The baroreceptor reflex was studied in eleven patients, aged 69 +/- 6 years, scheduled for carotid endarterectomy under general anaesthesia. Nine were hypertensive. The anaesthetic protocol was the same for all the patients: premedication with morphine and scopolamine, induction with 5 mg.kg-1 thiopentone, 6 micrograms.kg-1 fentanyl and 0.01 mg.kg-1 pancuronium bromide. All the patients were intubated and ventilated with a mixture of nitrous oxide and oxygen. Fentanyl, 100 micrograms, was routinely given at the time of incision. Baroreflex sensitivity was tested using Smyth's method, with a bolus of 75 micrograms trinitrin and plotting changes in heart rate against those in systolic blood pressure. Electrocardiogram, invasive arterial blood pressure and airway pressure were simultaneously recorded. PaCO2 and PaO2 were measured during arterial clamping. The tests were carried out before clamping, 2 min later and 10 to 20 min after the last injection of fentanyl. In the seven patients for whom clamping lasted more than 15 min, a further test was carried out after administration of 0.4 +/- 0.05 vol% halothane (Datex analyser) for 5 min. During anaesthesia, baroreflex sensitivity was low (1.8 +/- 0.3 ms.mmHg-1). After clamping, there was only a significant change in Pasys, with no changes in heart rate or blood gas values (129 +/- 8 mmHg before clamping; 167 +/- 12 mmHg after clamping; n = 8; p less than 0.01). After halothane administration, the sensitivity slope decreased, but not significantly. Moreover, halothane decreased the R-R intervals (1140 +/- 84 after clamping; 963 +/- 76 under halothane; n = 6; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of isoflurane in a closed-circuit. Economic advantages

The present study was designed to assess whether isoflurane requirement was significantly affected by fresh gas flow in a closed-circuit system. Sixty patients scheduled for orthopaedic procedures were randomly assigned into three groups. In group A (n = 20), anaesthesia was conducted with a fresh gas flow of 482.5 +/- 186.6 ml X min-1, corresponding to the patient's metabolic demand. In group B (n = 20), the fresh gas flow was 2000 ml X min-1. In group C (n = 20), it was adjusted to the ventilation minute, i.e. 7145 +/- 986 ml X min-1. Artificial ventilation was conducted using a tidal volume of 10 ml X kg-1 and a rate of 10 to 12 c X min-1. Anaesthesia was induced after 10 min denitrogenation with fentanyl (4 micrograms X kg-1), thiopentone (4 mg X kg-1) and vecuronium (0.1 mg X kg-1). FIO2 was then brought to 0.5 in nitrous oxide and was monitored continuously using a polarographic oxymeter. Liquid isoflurane was injected in the expiratory limb of the circuit using an electrical syringe driver. Alveolar concentration of isoflurane was set at 0.92 vol. % according to Lowe and Ernst. Statistical analysis was carried out using Student's test for means. Anaesthesia lasted 138 +/- 88.3 min in group A, 125.5 +/- 45.1 min in group B and 146.5 +/- 50 min in group C, no difference being significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Functional residual capacity and respiratory mechanics as indicators of aeration and collapse in experimental lung injury

Increased functional residual capacity (FRC) and compliance are two desirable, but seldom measured, effects of positive end-expiratory pressure (PEEP) in mechanically ventilated patients. To assess how these variables reflect the morphological lung perturbations during the evolution of acute lung injury and the morphological changes from altered PEEP, we correlated measurements of FRC and respiratory system mechanics to the degree of lung aeration and consolidation on computed tomography (CT). We used a porcine oleic acid model with FRC determinations by sulfur hexafluoride washin-washout and respiratory system mechanics measured during an inspiratory hold maneuver. Within the first hour, during constant volume-controlled ventilation with PEEP 5 cm H(2)O, FRC decreased by 45% +/- 15% (P = 0.005) and compliance decreased by 35% +/- 12% (P = 0.005). Resistance increased by 60% +/- 62% (P = 0.005). Only the FRC changes correlated significantly to the decreased aeration (R(2) = 0.56; P = 0.01) and the increased consolidation (R(2) = 0.43; P = 0.04) on CT. When the PEEP was changed to either 10 or 0 cm H(2)O, there were larger changes in FRC than in compliance. We conclude that, in our model, FRC was a more sensitive indicator of PEEP-induced aeration and recruitment of lung tissue and that FRC may be a useful adjunct to PaO(2) monitoring. IMPLICATIONS: Lung injury was quantified on computed tomography and related to monitored values of functional residual capacity and mechanical properties of the respiratory system. We found the functional residual capacity to be a more sensitive marker of the lung perturbations than the compliance. It might be of value to include functional residual capacity in the monitoring of acute lung injury.     

The effects of ephedrine and phenylephrine on arterial partial pressure of oxygen

The changes in arterial partial pressure of oxygen were studied following intravenous injections of either ephedrine, 0.2mg.kg-1, or phenylephrine 2.5 micrograms.kg-1, to restore arterial hypotension. Eighty one adult patients underwent general anesthesia, being mechanically ventilated, were divided into two groups; both lung ventilation group (68 patients) and one lung ventilation group (13). In both lung ventilation group, PaO2/FIO2 changed from 390 +/- 132 to 400 +/- 137 mmHg, and 428 +/- 124 to 438 +/- 136 following administrations of ephedrine and phenylephrine, respectively. The results were not statistically significant. In the one lung ventilation group, PaO2/FIO2 did not change significantly from 190 +/- 45 to 186 +/- 29 with ephedrine and 267 +/- 138 to 317 +/- 230 with phenylephrine. We observed neither arrhythmia, severe hypoxemia, nor decrease in PaO2/FIO2 by more than 100mmHg. These results indicate that with respect to changes in arterial partial pressure of oxygen, the clinical doses of ephedrine and phenylephrine can be safely administered to patients under general anesthesia to restore arterial hypotension.     

Effect of halothane,enflurane and isoflurane on the end-systolic pressure-length relationship

Myocardial contractility was measured using the end-systolic pressure-length (ESPL) relationship in dogs subjected to increasing concentrations of halothane (0.5-2 per cent), enflurane (0.77-2.6 per cent) or isoflurane (0.70-2.13 per cent), combined with an infusion 7 micrograms X kg-1 X min-1 of fentanyl, after induction of anaesthesia with 15 mg X kg-1 thiopentone. The relationship between the concentrations of the different drugs and contractility (ESPL) can best be described by ESPL = a + b/(MAC fraction) where "a" is a constant and "b" is the slope of the curve relating ESPL to MAC. At 1.0 MAC values, the ESPL for halothane (69.04 +/- 25.83 mmHg X mm-1) did not differ from that of isoflurane (63.19 +/- 17.36 mmHg X mm-1). However, the myocardial contractility during 1.0 MAC halothane and isoflurane anaesthesia was better preserved than that of enflurane (38.66 +/- 9.73 mmHg X mm-1: p less than 0.01, p less than 0.05 respectively).     

Lung lavage and surfactant replacement for hydrochloric acid aspiration in rabbits

Hydrochloric acid (0.1 N, 5.0 ml.kg-1 in total) was administered intratracheally to 28 adult rabbits anesthetized with pentobarbital and mechanically ventilated with pure oxygen. When the PaO2 decreased to 14.1 +/- 2.8 kPa (mean +/- s.d.), the PaCO2 increased to 8.9 +/- 2.5 kPa, and the minute ventilation (VE) decreased to 51 +/- 8% of the baseline value, animals were divided into 4 groups. The deteriorated values did not improve in the non-treated (control) animals, whereas the animals treated with lung lavage and surfactant replacement showed a significant increase in PaO2 to 35.1 +/- 12.2 kPa, and maintained lower PaCO2 and larger VE than the controls. These parameters showed no significant improvement with surfactant replacement alone, and deteriorated further with lung lavage alone. The minimum surface tension (gamma min) of the edema fluid that accumulated in the airways after acid administration was 22.5 +/- 1.7 mN.m-1, and was not lowered by adding surfactant preparation (10 mg.ml-1) whose original gamma min was less than 2 mN.m-1. We concluded that surfactant inhibition by edema fluid was a cause of respiratory failure, and that lung lavage followed by surfactant replacement might be of therapeutic value for acid aspiration.     

The effect of pre-induction glycopyrronium on the haemodynamic response of elderly patients to anaesthesia with propofol

This study investigated whether pretreatment with glycopyrronium can attenuate the hypotension caused by anaesthesia of the elderly with propofol. Twenty elderly patients (77.1 +/- 2.44 years, mean +/- SEM) of ASA physical status 2 or 3 scheduled for elective urological procedures were given glycopyrronium 0 (n = 10) or 5 micrograms.kg-1 (n = 10) in a randomised, double-blind manner, 5 min before induction of anaesthesia with propofol infused at 600 ml.h-1 (average induction dose 1.7 +/- 0.06 mg.kg-1, mean +/- SEM) followed by maintenance with a propofol infusion at 10 mg.kg-1.h-1. Although glycopyrronium significantly increased heart rate (p less than 0.01, ANOVA), the decrease in blood pressure 2 and 5 min after induction was similar in both groups. The study had a power of 80% to detect a 20 mmHg difference in systolic arterial pressure between treatment groups with p less than 0.05.     

Functional residual capacity in anesthetized children: normal values and values in children with cardiac anomalies

To assess the increase in functional residual capacity (FRC) with growth, FRC was measured after induction of anesthesia in two groups of children. One group consisted of 74 children, 0.1-11.2 yr of age, without signs of cardiorespiratory disease (referred to here as "normal" children), and the other of 21 children, 0.2-6.9 yr of age, with cardiac malformations. Anesthesia was maintained with halothane in the normal children and with fentanyl, droperidol, and nitrous oxide in the children with cardiac anomalies. All patients were paralyzed, their tracheas intubated, and their lungs mechanically ventilated. FRC was measured with an automated tracer gas washout technique. In 70 patients the measurements were performed in duplicate with a mean coefficient of variation of 2.0%. FRC correlated significantly with height, weight, and age in both groups. Multiple regression analysis for both groups considered together indicated no significant improvement when factors for the sex of the child or for the presence of cardiac anomalies were incorporated into the model. In normal children the simple linear and nonlinear regression equations for FRC (in milliliters) versus height (in centimeters) were: FRC = -529 + 9.48 x height, r = 0.96; and FRC = 0.00175 x height2.66, r = 0.97, respectively. The corresponding equations for FRC (in milliliters) versus weight (in kilograms) were: FRC = -92 + 29.9 x weight, r = 0.93; and FRC = 9.51 x weight1.31, r = 0.95.(ABSTRACT TRUNCATED AT 250 WORDS)     

LUNG FUNCTION IN THE SUPINE AND LATERAL DECUBITUS POSITIONS IN ANAESTHETIZED INFANTS AND CHILDREN

We have measured dynamic lung compliance or static lung thoraxcompliance, functional residual capacity (FRC), and two indicesof pulmonary gas mixing (pulmonary clearance delay (PCD) andsingle breath alveolar mixing efficiency (SBAME)) in 25 childrenin the supine and lateral decubitus position during nitrousoxidehalothane anaesthesia. Fifteen children (5 month-8 yr)breathed spontaneously and 10 (4 month-9 yr) underwent mechanicalventilation. Tidal volume and rate of ventilation were, respectively.3.5–6.6 ml kg^–1 and 22–46 b.p.m. in spontaneouslybreathing supine children, and 8.3–15 ml kg^–1 and20–30 b.p.m. in mechanically ventilated supine children,and did not differ significantly in the lateral position. Therewas no significant change in compliance when the child was turnedto the lateral position, but FRC increased from 22 (SD 7) to25 (8) ml kg^–1 (P<0.01) in the spontaneously breathinggroup and from 19 (6) to 24 (8) ml kg^–1 (P<0.01) inthe other group. In spontaneously breathing children, PCD andSBAME indicated a somewhat impaired pulmonary gas mixing (P<0.05)after the child had been turned to the lateral position, butno change occurred in the other group. These findings suggestthat the distribution of ventilation in anaesthetized childrenin the lateral position is similar to that reported previouslyin anaesthetized adults. Presented in part at the Annual Meeting of the American Societyof Anesthesiologists, Atlanta, October 1987.