Does isolation technique have any impact on inhalational exposure of neuroanaesthetists to sevoflurane during craniotomies?

Abstract

IntroductionThere are multiple reports of the use of vasopressin with phaeochromocytoma resections in adults. Support for vasopressin in the paediatric patient, however, is not quite as substantiated. We report such a case to add to the limited evidence for its use in a young child. Case reportA 6-year-old boy, weighing 21 kg, was admitted to a local District General Hospital with severe headaches not responding to simple analgesics. His initial blood pressure was recorded as 166/91 mmHg. This was persistently elevated and, subsequently, he developed vomiting, photophobia and bilateral papilloedema. He was referred to our institution for further investigation and treatment. Tests showed raised urinary levels of catecholamine metabolites over 24 h and a subsequent computed tomography (CT) scan confirmed a left-sided adrenal phaeochromocytoma. He was started on gradually increasing doses of phenoxybenzamine and atenolol, and a laparoscopic adrenalectomy was planned for within 6 weeks. In the meantime, his blood pressure was controlled with phenoxybenzamine, 20 mg twice daily, and atenolol, 30 mg once daily. Cardiac workup included electrocardiography and echocardiography, which were both normal. PreoperativeThe boy was admitted to our hospital 48 h before surgery when he was noted to have an increased BP of 140/80 mmHg. In addition to the phenoxybenzamine and atenolol, he was started on hydralazine 10 mg three times daily; all three of which were continued until the morning of surgery. As a premedication, he was given midazolam (0.5 mg kg À1 orally) 30 min prior to coming to theatre. The BP before induction of anaesthesia was 105/68 mmHg. Induction of anaesthesiaAnaesthesia was induced with intravenous propofol (4 mg kg À1 ) and fentanyl (slowly titrated up to 5 mg kg À1 ), and he was paralysed with rocuronium (1 mg kg À1 ). After endotracheal intubation, large bore peripheral intravenous catheters, an arterial line, a central venous line and an epidural catheter (L1/2) were inserted. The epidural was dosed with 10 ml of 0.25% ropivacaine over a period of 30 min. The patient remained normotensive with blood pressure readings around 100/50 mmHg. Anaesthesia was maintained with oxygen, air and isoflurane. Operative procedureThe operation was performed in the right lateral position via a laparoscopic retroperitoneal route, using three 5 mm operative ports and gas insufflation with CO 2 . The ventilation was adjusted to maintain normocapnia throughout. Dissection of the adrenal gland was kept to an absolute minimum until its blood vessels were identified. It was clear that any contact with the adrenal gland did cause major spikes in blood pressure. As soon as these vessels were clearly identified, the adrenal vein was double clipped and divided, the remaining vessels were then divided. The adrenal gland was removed intact with no damage to the surrounding structures, and there was no significant bleeding or breach of the peritoneum.During the operation, sodium chloride 0.9% was infused at a rate of 10 ml kg À1 h À1 for...

Does standing or sitting position of the anesthesiologist in the operating theatre influence sevoflurane exposure during craniotomies?

“…1, when a laminar system is used, the gas flow is driven toward the anesthetist located at the side of the patient. As we proved previously during our measurements, the main source of sevoflurane evaporation is the patient’s mouth [7] and the proximity of the anesthetist located at the side contributes to higher exposure due to the open isolation drape driving the evaporated gas toward the anesthetist [8]. Therefore, the open isolation along with the air flow due to the laminar system may result in higher anesthetic exposure for the sitting anesthetist (See Fig.…”

“…In a previous study it was also proven that positioning of anesthesia at the feet of the patient (rather than at the side) may decrease anesthetic exposure [8]. However, in some institutions anesthetists insist on positioning anesthesia team at the side because, in their judgment, the patient is better accessible this way.…”

Occupational Hazards of Halogenated Volatile Anesthetics and their Prevention: Review of the Literature

“…In a recent study, Tankó et al revealed that during intracerebral surgeries, the evaporated amount of sevoflurane is the highest at the anesthetist's breathing zone, the most important source of this leakage is the patients' mouth [4] and the amount of evaporated gas is independent of the endotracheal tube cuff pressure [5]. It has been also demonstrated that exposure of the anesthesia staff can be decreased by proper positioning of the anesthesia personnel during intracranial surgery [6].…”