Difficult Extubation: Calming the Sympathetic Storm

Preanesthetic dexmedetomidine 1 µg/kg single infusion is a simple, easy, and economic adjuvant for general anesthesia

Background

Dexmedetomidine is an α₂-adrenoreceptor agonist with sedative, analgesic and anxiolytic effects, and it has more selective α₂-adrenergic effect than clonidine. We evaluate the effect of preansethetic dexmedetomidine 1 µg/kg single infusion on sedation, hemodynamics, anesthetic consumption, and recovery profiles during anesthesia.

Methods

Forty-two female patients with American Society of Anesthesiologists physical status I or II undergoing gynecologic surgery with anticipated operation time of 2 h, were randomly assigned to receive dexmedetomidine 1 µg/kg (Dex group) or saline (control group) iv over 10 min before anesthetic induction. After tracheal intubation with propofol 2 mg/kg, cisatracurium 0.15 mg/kg iv, anesthesia was maintained with sevoflurane, O₂ 50%, N₂O 50% around a BIS value of 40.

Results

After study drug infusion, BIS of Dex group was lower than that of control group (93.9 ± 3.1 vs 51.5 ± 5.2, P < 0.05). Mean arterial pressure (MAP) and heart rate (HR) after intubation were increased in control group, but did not change in Dex group. During maintenance, there was no difference in MAP between groups, but HR of Dex group was lower compared to that of control group. End-tidal concentration (2.0 ± 0.5 vol% vs 1.4 ± 0.3 vol%, P < 0.05) and total cumulative consumption of sevoflurane (34.6 ± 3.8 ml vs 26.5 ± 5.3 ml, P < 0.05) were lower in Dex group than in control group. Recovery profiles, modified Aldrete score, postoperative nausea vomiting, and visual analogue pain score were not significantly different between groups.

Conclusions

Preanesthetic dexmetomidine 1 µg/kg single infusion is a simple, easy, and economic general anesthetic adjuvant that maintains stable hemodynamics and decrease anesthetic consumption without the change of recovery profiles.

Difficult Airway Society Guidelines for the management of tracheal extubation

Tracheal extubation is a high-risk phase of anaesthesia. The majority of problems that occur during extubation and emergence are of a minor nature, but a small and significant number may result in injury or death. The need for a strategy incorporating extubation is mentioned in several international airway management guidelines, but the subject is not discussed in detail, and the emphasis has been on extubation of the patient with a difficult airway. The Difficult Airway Society has developed guidelines for the safe management of tracheal extubation in adult peri-operative practice. The guidelines discuss the problems arising during extubation and recovery and promote a strategic, stepwise approach to extubation. They emphasise the importance of planning and preparation, and include practical techniques for use in clinical practice and recommendations for post-extubation care.

Planning for early emergence in neurosurgical patients: a randomized prospective trial of low-dose anesthetics

BACKGROUND

For early detection of a cerebral complication, rapid awakening from anesthesia is essential after craniotomy. Systemic hypertension is a major drawback associated with fast tracking, which may predispose to formation of intracranial hematoma. Although various drugs have been widely evaluated, there are limited data with regards to use of anesthetics to blunt emergence hypertension. We hypothesized that use of low-dose anesthetics during craniotomy closure facilitates early emergence with a decrease in hemodynamic consequences.

METHODS

Three emergent techniques were evaluated in 150 normotensive adult patients operated for supratentorial tumors under standard isoflurane anesthesia. At the time of dural closure, the patients were randomized to receive low-dose propofol (3 mg.kg(-1).h(-1)), fentanyl (1.5 microg.kg(-1).h(-1)) or isoflurane (end-tidal concentration of 0.2%) until the beginning of skin closure. Nitrous oxide was discontinued after head dressing.

RESULTS

Median time to emergence was 6 min with propofol, 4 min with fentanyl, and 5 min with isoflurane (P=0.008). More patients had hypertension in the pre-extubation compared with extubation or postextubation phase (P=0.009). Comparing the three groups, fewer patients required esmolol with fentanyl use overall, and in the pre-extubation phase (P=0.01). Significant midline shift in the preoperative cerebral imaging scans was found to be an independent risk factor for emergence hypertension.

CONCLUSIONS

Pain during surgical closure may be an important cause of sympathetic stimulation leading to emergence hypertension. The use of low-doses of fentanyl during craniotomy closure is more advantageous than propofol or isoflurane for early emergence in neurosurgical patients and is the most effective technique for preventing early postoperative hypertension.

Extubation of the surgically resected airway — a role for remifentanil and propofol infusions

PURPOSE

To report the use of propofol and remifentanil infusions to facilitate smooth extubation of a surgically resected airway.

CLINICAL FEATURES

A 19-yr-old man weighing 85 kg was scheduled for tracheal resection surgery following postintubation tracheal stenosis. He had a relatively long segment (4 cm) of his trachea resected and anastomosed. Postoperatively, he was sedated and electively ventilated for four days in a chin to chest position by stay sutures. In order to reduce any risk of traumatic disruption to the tracheal anastomosis, we planned to extubate his trachea under light general anesthesia. Attempts to extubate his trachea using propofol and alfentanil infusions failed. We used propofol and remifentanil infusions to achieve a state of sedate cooperation and extubated his trachea with fibreoptic bronchoscope guidance.

CONCLUSION

Propofol and remifentanil infusions in combination can facilitate successful extubation of the surgically resected airway with high risk of disruption.

Dexmedetomidine in anaesthesia

PURPOSE OF REVIEW

The development of dexmedetomidine, a potent and highly selective alpha2-adrenoceptor agonist, has created new interest in the use of alpha2-adrenoceptor agonists, and has led to its evaluation in various yet non-approved perioperative settings. The current review focuses on the usefulness of dexmedetomidine in anaesthesia practice.

RECENT FINDINGS

Recently acquired knowledge and experience with dexmedetomidine in perioperative use will be presented and discussed in the context of known pharmacological properties.

SUMMARY

Dexmedetomidine offers beneficial pharmacological properties, providing dose-dependent sedation, analgesia, sympatholysis and anxiolysis without relevant respiratory depression. The side-effects are predictable from the pharmacological profile of (2-adrenoceptor agonists. In particular, the unique sedative properties of dexmedetomidine resulted in several interesting applications in anaesthesia practice, promising benefits in the perioperative use of this compound. However, dexmedetomidine was approved for sedation in the intensive care unit in the USA in 1999, and administration in anaesthesia practice remains an 'off-label' use. Further studies are needed to establish the role of dexmedetomidine in the perioperative period.