Recognition and management of catheter-induced pulmonary artery rupture.

BACKGROUND: Catheter-induced pulmonary artery rupture is a well-recognized complication of invasive monitoring, but the risk has not diminished. Although commonly associated with cardiopulmonary bypass, injuries also occur in intensive care. Definitive proof requires pulmonary angiography or autopsy. Many cases are never reported, and lesser injuries are probably under-diagnosed. METHODS: Seven cases fulfilling accepted diagnostic criteria discovered over 2 years are described in four groups illustrating the common modes of presentation: hemoptysis with hypoxemia, exsanguination, delayed recurrent hemorrhage, and bleeding with cardiopulmonary bypass. RESULTS: One patient had a planned elective operation deferred. Four patients were being monitored in intensive care. Two of them died of pulmonary artery rupture. Two other patients had bleeding on weaning from cardiopulmonary bypass. One settled with conservative treatment, the other survived after extracorporeal life support. Recognition and management are discussed, emphasizing means of avoiding pulmonary resection. CONCLUSIONS: Catheter-induced pulmonary artery rupture is unavoidable. Constant awareness is essential. A plan of management is presented. Extracorporeal life support may help to avoid pulmonary resection. Early pulmonary angiography is advocated for accurate diagnosis and to enable treatment by embolization.

Haemodynamic response to simulated haemorrhage in the rabbit: interaction of i.v. anaesthesia and hypoxia.

We have studied in eight rabbits the cardiovascular effects of midazolam, propofol and alfentanil with graded hypoxia. Central blood volume was reduced progressively by gradual inflation of a thoracic vena cava cuff so that cardiac index (CI) decreased at a constant rate. Under control conditions the haemodynamic response was biphasic. During phase I, mean arterial pressure (MAP) was maintained by a progressive decrease in systemic vascular conductance (SVCI). When CI had declined to a critical level, phase II occurred with an abrupt increase in SVCI and decrease in MAP. Phase I was prolonged by hypoxia, alfentanil and midazolam, but the effects were not additive. Phase I was shortened by propofol and this effect increased with hypoxia. The gradient of the SVCI response in phase I was also reduced by propofol > midazolam, but not by alfentanil. The occurrence of phase II was less frequent during alfentanil infusion than midazolam and propofol with all of the inspired gas mixtures. Thus the opioid was protective against circulatory collapse with hypoxia and simulated hypovalaemia.

Normal postoperative gastric emptying after orthopaedic surgery with spinal anaesthesia and i.m. ketorolac as the first postoperative analgesic.

We have assessed the effect of i.m. ketorolac or morphine on early postoperative gastric emptying of liquids in patients undergoing orthopaedic surgery with spinal anaesthesia. Liquid gastric emptying was measured by absorption of paracetamol with patients acting as their own controls. There was no delay after ketorolac 30 mg, but morphine 10 mg resulted in marked delay. There was no difference in postoperative visual analogue pain scores between treatments.

Interactions between the circulatory effects of central hypovolaemia and arterial hypoxia in conscious rabbits.

1. Eight conscious rabbits were repeatedly subjected to progressive reduction in central blood volume by gradually inflating a thoracic inferior vena caval-cuff so cardiac index (CI) fell at a constant 8.5% of baseline/min. 2. Caval-cuff inflations were performed after 10 min exposure to 100, 21, 12-14 and 8-10% O2, with and without the addition of 3-4% CO2, in randomized order. 3. The haemodynamic response to progressive reduction in central blood volume was biphasic. In Phase I, systemic vascular conductance index (SVCI) fell linearly, supporting mean arterial pressure (MAP). When CI had fallen to a critical level, Phase II occurred in which SVCI rose abruptly, MAP plummeted and respiratory drive progressively increased. 4. During Phase I, there were independent linear relationships between PaCO2 (but not PaO2) and the rates at which SVCI and MAP changed during the progressive fall of CI. The higher the level of PaCO2, the greater was the rate of fall of SVCI and the less the rate of fall of MAP. 5. There was an inverted U-shaped effect of PaO2 on the level of CI at which Phase II occurred: (a) during hyperoxia (100% O2), Phase II occurred later than during normoxia (21% O2); and (b) across the normoxic and hypoxic gas mixtures (21-8% O2, with and without added CO2), there was an independent linear relationship between PaO2 (but not PaCO2 or PaO2 x PaCO2) and the level of CI at which Phase II occurred. That is, the lower the level of PaO2, the later was the onset of Phase II. This interaction is best explained by an increased level of central sympathetic vasoconstrictor drive during hypoxia.

Experimental ischaemic tourniquet pain delays gastric emptying of semi-solids in healthy volunteers.

The effect of controlled, experimental ischaemic pain, induced by tourniquet, on gastric emptying of a semi-solid meal of Tc-99m labelled Chelex-100 resin oatmeal was assessed in seven healthy volunteers, each acting as his/her own control. In the pain study, the submaximal effort tourniquet test was applied immediately, 30 min and 45 min after beginning of the study. Pain intensity was rated during the procedure using a linear visual analogue scale (VAS). All subjects participating in the study assessed their pain as close to maximal tolerance after 2-4 min. The pain stimulus caused an immediate acceleration, followed by a reproducible, significant delay in gastric emptying relative to the control situation. The median reduction in meal emptied after 60 min in the pain study was 15% P = 0.035). There was no difference in the duration of the lag period between the groups.

Inter- and intrasubject variability of gastric emptying in healthy volunteers measured by scintigraphy and paracetamol absorption.

1. Inter- and intrasubject variability in the gastric emptying of semisolids and liquids was measured by scintigraphic emptying of radionuclide-labelled semisolid and from paracetamol absorption in ten healthy volunteers of both sexes. 2. The intrasubject variability was not statistically significant for any of scintigraphic or paracetamol absorption parameters. 3. The intersubject variation was significant for all scintigraphic and paracetamol absorption parameters. 4. In women, the gastric emptying rate of semisolid decreased linearly during the menstrual cycle. 5. The lag period and paracetamol absorption parameters were unrelated to the day of the menstrual cycle day. 6. There was no statistically significant relationship between scintigraphic and paracetamol absorption parameters.

The effect of phentolamine on basal and pethidine-induced inhibition of gastric emptying in healthy volunteers.

1. The effect of phentolamine 5 mg i.v. on basal and pethidine-induced inhibition of gastric emptying of semisolid TC-99m labelled Chelex-100 resin/oatmeal was studied in ten healthy volunteers. 2. Each volunteer acted as his/her own control. 3. Basal gastric emptying remained unchanged after administration of phentolamine. 4. Administration of phentolamine reversed the pethidine-induced inhibition of gastric emptying.

The effect of oxytocin on basal and pethidine-induced delayed gastric emptying.

1. Continuous infusion of oxytocin (0.33 u min-1) accelerated gastric emptying of semisolid TC-99m labelled Chelex-100 resin/oatmeal in 10 healthy volunteers under basal conditions. 2. Administration of oxytocin did not change the pattern of gastric emptying delayed by pethidine. 3. The emptying pattern of semisolid has confirmed the existence of a lag phase.

Transitory postural vasomotor dysfunction in the finger after short term hand vibration.

The transitory effects of hand vibration (ah, w = 3.16 m/s2 during three minutes) on postural vasomotor functions of skin capillary blood flow rate in the finger were studied by the local 133xenon washout technique in ten men with vibration induced white finger (VWF), nine men professionally exposed to hand-arm vibration but without finger symptoms (HAV), and eight male controls (MC). The following postural vasomotor functions were measured: (a) the vasomuscular, non-neurogenic autoregulation, tested by raising the finger 20 cm; (b) the local venoarteriolar vasoconstrictor axon reflex, tested by lowering the finger 40 cm; and (c) the central sympathetic vasoconstrictor reflex elicited by central baroreceptors and tested by changing the body posture from supine to sitting upright. Before short term vibration the vasoconstriction elicited by central baroreceptors was increased in VWF (p less than 0.01) and normal in HAV (p greater than 0.10). The local axon reflex and the autoregulation functioned normally in VWF and HAV (p greater than 0.30). Three minutes after vibration, autoregulation was abolished and the functions of the central and local sympathetic vasoconstrictor reflexes were equally impaired in all three groups (p less than or equal to 0.01). All three vasomotor functions were completely restored 60 minutes after vibration in MC (p greater than 0.10) and also 30 minutes after vibration in one male control (p greater than 0.20). The results indicate a hyperreactivity of the central sympathetic nervous system in VWF, and a transitory, impaired function of digital arterioles after short term vibration in all groups.

Vibration elicited vasoconstrictor reflex in Raynaud's phenomena.

The fingers of seven women with primary Raynaud's phenomenon (PRP), 10 female controls, seven men with vibration induced white finger (VWF), and eight male controls were exposed to vibration and the relative change in finger capillary blood flow was measured by an atraumatic 133xenon washout technique without and during proximal nervous blockade. All four groups showed a vasoconstriction to vibration (p less than or equal to 0.02) which was abolished by proximal nervous blockade. Women with PRP had an augmented response to vibration (p less than 0.01) and men with VWF had a normal response (p greater than 0.10) when compared with that of their respective sex matched controls. The results show the existence of a vibration elicited central sympathetic vasoconstrictor reflex in the normal finger and in fingers affected by PRP and VWF. The results indicate a hyperreactivity of the central sympathetic nervous system in PRP and VWF and a dysfunction of the peripheral sensory nerve fibres in subjects with VWF. The described vibration test may be of guidance in the differentiation of PRP from VWF.

The effect of droperidol on fentanyl-influenced gastric emptying in man.

The effect of droperidol on gastric emptying was determined from the rate of paracetamol absorption in seven healthy adult volunteers who received fentanyl, each acting as his/her own control. On each occasion the subjects were given droperidol 2.5 mg or normal saline (placebo) i.v. in double-blind fashion. On both occasions, 20 and 50 min later a dose of 0.0015 mg kg-1 fentanyl was given. Ten minutes after the first fentanyl dose, the subjects ingested 20 mg kg-1 paracetamol with 200 ml of water. Our findings demonstrate that droperidol was not able to accelerate gastric emptying in subjects receiving subsequent small doses of fentanyl. Furthermore, the delayed absorption pattern of paracetamol on both occasions suggests that gastric emptying is retarded with or without droperidol.

Effect of chlorpromazine on drug absorption and gastric emptying in man.

In a double-blind study the effect of a single IV dose (25 mg) of chlorpromazine on gastric emptying, as determined by the rate of paracetamol absorption, was measured in seven healthy volunteers. Each volunteer acted as his/her own control. There was no significant difference between the maximum paracetamol concentration, the time to reach the plasma maximum concentration, and the area under the plasma concentration time curve from 0-120 minutes on the two occasions, indicating unchanged gastric emptying after administration of chlorpromazine.

Exaggerated postural vasoconstrictor reflex in Raynaud's phenomenon.

The central and local regulation of capillary blood flow in the finger was studied by the local xenon-133 washout technique in women with primary Raynaud's phenomenon, men with vibration induced white finger, and their respective sex matched controls. The vasoconstrictor response to venous stasis of 40 mm Hg elicited by local reflex was normal in both types of Raynaud's phenomenon. Change in posture from lying to sitting induced vasoconstriction in all groups, which was abolished by proximal nervous blockade. The vasoconstrictor response to sitting was augmented in both groups of subjects with Raynaud's phenomenon compared with their sex matched controls. These results show the existence of central and local postural vasoconstrictor reflexes in normal fingers. In both types of Raynaud's phenomenon there was hyperreactivity of the central sympathetic nervous system to orthostatic stress and normal function of digital arterioles and postganglionic sympathetic nerve fibres.

The effect of spinal analgesia and surgery on peroperative drug absorption and gastric emptying in man.

Paracetamol 20 mg kg-1 dissolved in 200 ml of water was given by mouth to seven patients undergoing minor orthopaedic surgery in spinal analgesia, and again 2 weeks later. The rate of paracetamol absorption was significantly delayed by spinal analgesia and surgery, indicating an inhibition of peroperative drug absorption and gastric emptying. The effect of spinal analgesia on gastric emptying was not able to normalize the delayed peroperative gastric emptying produced by surgery, and suggests that surgery is an important factor in peroperatively delayed gastric emptying.

Influence of cigarette smoking on the risk of acid pulmonary aspiration.

Twenty-five non-smokers and 35 smokers who had abstained overnight from cigarette smoking and were undergoing minor elective orthopaedic surgery were studied in order to compare gastric volume and pH. There was no significant difference in aspirated volume and pH both just after intubation and prior to extubation between the two groups, thus indicating that habitual smokers undergoing elective surgery in general anaesthesia do not have increased risk of acid pulmonary aspiration compared with non-smokers.

The relationship between gastric emptying of semisolids and paracetamol absorption.

The relationship between gastric emptying rate of semisolid Tc-99m labelled Chelex-100 resin/oatmeal and paracetamol absorption was determined simultaneously in seven healthy volunteers. There was no significant correlation between the half-time of gastric emptying and the time of the peak serum paracetamol concentration. There was no significant correlation between the area under the serum paracetamol concentrations at 60 and 90 min and the % meal emptied in 60 and 90 min respectively. Three subjects showed a lag phase in gastric emptying pattern, while the other four showed the emptying curves without evidence of a delayed phase of emptying. Individual values of gastric emptying determined by the methods varied widely.

Prevention of silent aspiration due to leaks around cuffs of endotracheal tubes.

Significant aspiration may occur around correctly inflated high volume, low pressure endotracheal tube cuffs. The prevention of silent aspiration due to leaks around cuffs of endotracheal tubes was investigated during general anesthesia for hip replacement in 47 patients. The patients were randomly assigned to one of three groups, in which one of three endotracheal tubes of different designs were used for intubation. The following three tubes were used: the red rubber Rüsch tube with low residual volume cuff, inflated to minimum occluding volume; the Mallinckrodt Hi-Lo tube with high residual volume cuff; the NL tube with high residual volume cuff and automatic cuff pressure regulation. The cuffs on the Mallinckrodt and the NL tubes were inflated to 29-31 cm H2O. One hour before termination of the surgical procedure, 1 ml methylene blue dye was injected into the trachea just above the cuff through a thin channel built into the tubes. At termination of the operation, the trachea below the cuff was inspected with a fiberoptic bronchoscope. Aspiration was found in 12.5% with the Rüsch tube, in 31.2% with the Mallinckrodt tube, and in 0% with the NL tube. Our results show that silent aspiration is still a problem with standard endotracheal tubes, but that it may be minimized by use of appropriate tubes, cuffs, and control of cuff inflation.