Cardiovascular responses to scalp infiltration with reduced concentration of adrenaline.

A prospective randomized controlled study was carried out in 41 adult neurosurgical patients to find out the hemodynamic effects following scalp infiltration with 0.5% lignocaine with or without adrenaline. The patients were divided randomly into two groups. Group I patients (n=21) received 0.5% lignocaine with adrenaline (1:8,00,000) for scalp infiltration and group II patients (n=20) received 0.5% lignocaine without adrenaline. Continuous monitoring of ECG, heart rate and arterial blood pressure was carried out every minute for 20 minutes following scalp infiltration. Blood loss while raising the scalp flap was assessed by the neurosurgeon who was unaware of the study. No significant hemodynamic disturbances were observed in either group. However, Group I patients had significantly (p=0.001) less bleeding on incision. From this study, we conclude that 0.5% lignocaine with adrenaline (1:8,00,000) does not give rise to any cardiovascular disturbances during and following scalp infiltration. Rather, it minimises blood loss while raising the craniotomy flap.

Potassium homeostasis during & after cardiopulmonary bypass.

Potassium homeostasis was studied in 30 patients undergoing cardiac surgery by employing cardiopulmonary bypass (CPB) and moderate hypothermia, and using morphine, N2O, relaxant anaesthesia. There was a trend for hypokalemia, and for maintaining a K+ level of 4-4.5 mmol/l, K+ infusion was required during CPB (9.017 mmol/m2 BSA/h). K+ infusion required in the post-operative period was considerably less (1.532 mmol/m2 BSA/h). There was no significant difference in the K+ levels of patients receiving preoperative diuretic therapy, as compared to those not receiving such therapy. Potassium requirement was significantly higher in patients under-going CABG and valvular heart disease, as compared to congenital heart disease. The mean urinary loss of K+ during bypass was found to be 2.95 mmol/m2 BSA/h, which was only 32 per cent of that required to be infused (9.017 mmol/m2 BSA/h). The mean excretion of K+ in the post operative period was significantly higher (4.53 mmol/m2 BSA/h) than K+ required to be infused during this period (1.532 mmol/m2 BSA/h).

End tidal carbon dioxide monitoring for detection of venous air embolism.

With the aim of defecting the potential hazard of air embolism, end tidal carbon dioxide (ETCO2) was monitored in 238 patients undergoing neurosurgery (in the sitting position), for early detection of venous air embolism (VAE). Fifty six episodes (26.3%) of significant fall in ETCO2 were observed in 41 patients (17.2%). Haemodynamic disturbances occurred in only 26 patients (10.9%) and were always preceded by a fall in ETCO2. Thirteen patients had positive air aspiration and cardiac murmurs were heard in only six. One patient suffered severe hypoxaemia (PaO2 = 55 mm Hg) whereas two had severe haemodynamic disturbances, but could be promptly resuscitated.