Venous air embolism: does the site of embolism influence the hemodynamic changes?

Three hundred and ninety-seven patients undergoing posterior cranial fossa surgery in the sitting position were prospectively studied to evaluate the incidence of venous air embolism (VAE) and its effects on hemodynamics. End-tidal carbon dioxide (ETC02) tension was monitored to diagnose VAE. A sudden and sustained decrease in ETC02 of more than 5 mmHg, in the absence of sudden hypovolemia, was presumed to be the result of VAE. The site of probable air entrainment (whether muscle, bone or tumor) was noted. Hemodynamic consequences were managed symptomatically. ETC02 monitoring detected VAE in 22% of the patients. The highest incidence of embolism resulted from muscles and tumor (40% in each case). Forty-two per cent of patients developed hypotension during the embolic episode (systolic BP less than 100 mmHg). Ten per cent of patients developed ventricular arrhythmias during the embolic episode. Air aspiration was successful in 4.8%. There were no statistically significant differences in the frequency of VAE among the different groups (P>0.05). Also, the frequency of hypotension and ventricular arrhythmias were not significantly different, irrespective of the source of VAE (P>0.05). The general condition of the patients in the preoperative stage had no influence on the incidence of embolism, hypotension or ventricular arrhythmias.

Hemodynamic response to skull pins application in children: effect of lignocaine infiltration of scalp.

BACKGROUND: Skull pins application following local anesthetic infiltration of scalp obtunds hemodynamic changes in adults. No such study is available in children. METHODS: 30 children undergoing elective suboccipital craniectomy with skull pins fixation, were randomly allocated either to control group I, or lignocaine group II. Whereas in group I, pins were applied without any scalp infiltration. In group II, pins were applied 1 min. after scalp infiltration with 0.5% lignocaine (plain) at each pin site. RESULTS: Mean arterial pressure and heart rate were recorded during pinning (peak increase),1,4,7 and 10 min later, and were compared with the baseline (parameters recorded approximately 20 min. after intubation). Mean arterial pressure in group I peaked from 77.0 +/- 9.19 to 113.87 +/- 13.7mmHg (P<0.001) and remained significantly high throughout the study period. In Group II peak increase in mean arterial pressure was from 91.64 +/- 16.39 to 101.85 +/- 15.87 mmHg (P<0.01) and remained high till 1 min. only. Pins placement resulted in significant increase in heart rate only during pinning (peak increase) and up to 1 min. in both the groups (P<0.01). CONCLUSIONS: In children, skull pins placement 1 min. after scalp infiltration with 0.5% lignocaine plain fails to prevent the hemodynamic changes arising during pins placement (peak change) and up to 1 min. after pins placement. However, the technique successfully blocks these changes beyond 1 min. post skull pins fixation.

Comparative study on proper placement of central venous catheters with & without stillete.

Observing a standard protocol, central venous catheterization was performed, via the right basilic vein, in 100 patients. At random, 50 patients received a catheter with stillete and 50 without stillete. Catheter tip was localized on a chest radiograph; 78 per cent with stilletes and 80 per cent without stilletes were properly positioned (either in the right atrium or the superior vena cava). Most common aberrant placement was in the right ventricle (14% of each type of catheters), and this did not produce any ventricular arrhythmias. Eight per cent of catheters with stillete and 6 per cent without stilletes were malplaced into the ipsilateral internal jugular vein. The incidence of proper and improper placement was similar with the two types of catheters. Silent catheter migration into the right ventricle is very frequent than recognized when an estimated catheter length is inserted without radiologic control.