Desflurane increases cerebral blood flow velocity when used for rapid emergence from propofol anesthesia in children

Comparative evaluation of atenolol and clonidine premedication on cardiovascular response to nasal speculum insertion during trans-sphenoid surgery for resection of pituitary adenoma: A prospective, randomised, double-blind, controlled study

Severe cardiovascular responses in the form of tachycardia and hypertension following nasal speculum insertion occur during sublabial rhinoseptal trans-sphenoid approach for resection of small pituitary tumours. We compare the effects of preoperative administration of clonidine (α-2 agonist) and atenolol (α-blocker) over haemodynamic response, caused by speculum insertion during trans-sphenoid pituitary resection. We enrolled 66 patients in age range 18-65 years, of ASA I–II, and of either sex undergoing elective sublabial rhinoseptal trans-sphenoidal hypophysectomy. Group I (control) received placebo, group II (clonidine) received tablet clonidine 5 µg/kg, and group III (atenolol) received tablet atenolol 0.5 mg/kg. The heart rate increased on speculum insertion and 5 and 10 minutes following speculum insertion as compared to the pre-speculum values in the control group, while no change in the heart rate was observed in other groups (P<0.05). There was a rise in the mean arterial pressure during and 5, 10, and 15 minutes after nasal speculum insertion in the control group, whereas it was not seen in other groups (P<0.05). We therefore suggest that oral clonidine and oral atenolol (given 2 hours prior to surgery) is an equally effective and safe method of attenuating haemodynamic response caused by nasal speculum insertion during trans-sphenoid pituitary resection.

Impact of anesthetic agents on cerebrovascular physiology in children

The role of the pediatric neuroanesthetist is to provide comprehensive care to children with neurologic pathologies. The cerebral physiology is influenced by the developmental stage of the child. The understanding of the effects of anesthetic agents on the physiology of cerebral vasculature in the pediatric population has significantly increased in the past decade allowing a more rationale decision making in anesthesia management. Although no single anesthetic technique can be recommended, sound knowledge of the principles of cerebral physiology and anesthetic neuropharmacology will facilitate the care of pediatric neurosurgical patients.

Transcranial Doppler and anesthetics

Transcranial Doppler (TCD) is widely used to investigate the effects of anesthetic drugs on cerebral blood flow. Its repeatability and non-invasivity makes it an ideal, first choice method. Anesthesia providers are required to be conscious of the cerebral hemodynamic effects of drugs given in their practice, especially in neurosurgery and in subjects with impaired brain functions. The purpose of this review is to present the basic concepts of the TCD technique and the effects on cerebral hemodynamics of the most popular anesthetic drugs evaluated using TCD ultrasonography.

CSF pressure measurement during anesthesia: an unreliable technique

BACKGROUND

The measurement of cerebrospinal fluid (CSF) pressure is necessary for many clinical indications. Its accuracy may be compromised in frightened or uncooperative children who find it difficult to relax sufficiently. The aim of the present study was to evaluate possible effects of general anesthesia on CSF pressure values.

METHODS

Lumbar puncture was performed under general anesthesia in 15 patients aged 4.5-20 years for the evaluation of headaches associated with a swollen optic nerve. Cerebrospinal fluid pressure was measured with a manometer when the patient was fully anesthetized (opening pressure) and then continuously recorded until the patient regained consciousness. The opening pressure was compared with the lowest pressure measured at the termination of the procedure (end-measurement pressure).

RESULTS

Seventeen pressure measurements were performed in 15 patients. In all but two measurements, differences were noted between the opening and end pressure, ranging from 5 to 13 cmH(2)O. The opening pressure was abnormally high in 16 measurements, and the end pressure was abnormally high in seven. The difference between the two measurements was highly significant (P < 0.001).

CONCLUSIONS

Lumbar puncture performed under general anesthesia may yield two pressure measurements. Many factors, such as hypercarbia and the anesthetic agent used, may influence the results. Owing to the dynamic changes in CSF pressure, measurements made under anesthesia may be unreliable.