The effect of increasing degrees of spinal flexion on cerebrospinal fluid pressure.

The effects of increasing degrees of flexion on cerebrospinal fluid pressure were investigated in 12 neurosurgical patients requiring lumbar subarachnoid drains. Cerebrospinal fluid pressure and central venous pressure were measured in three positions: fully flexed ('chin on chest'), flexed at ninety degrees and straight. There was a significant increase in cerebrospinal fluid pressure on moving from the fully flexed to the flexed position (p < 0.0001), but not from the flexed to the straight position. These results were mirrored by smaller changes in central venous pressure. In patients without intracranial pathology these increases in cerebrospinal fluid pressure are probably unimportant. However, intracranial pathology may result in low cerebral perfusion pressures and any increase in cerebrospinal fluid pressure in this group may be harmful. The fully flexed position should be avoided when inserting lumbar drains in at risk patients.

The effect of reversal of myoneural blockade on cerebrospinal fluid pressure following cerebral aneurysm surgery.

Drugs with a depolarizing action at the myoneural junction may cause a rise in intracranial pressure. Neostigmine, which is commonly used to reverse residual myoneural blockade, has a depolarizing action, and yet its effect on intracranial pressure is unknown. Lumbar cerebrospinal fluid pressure, which mirrors intracranial pressure, was determined in 12 patients undergoing cerebral aneurysm surgery. Cerebrospinal fluid pressure was measured during dense myoneural blockade and after its reversal with neostigmine. These effects on cerebrospinal fluid pressure were compared with those produced when the arterial partial pressure of carbon dioxide (PaCO2) rose from 4 to 5 kPa. After reversal of myoneural block, there was a small (non-significant) change in cerebrospinal fluid pressure from 3.6 to 4.3 kPa and a larger (significant) rise in cerebrospinal fluid pressure to 9.7 kPa when the PaCO2 was allowed to rise. In this group of patients, reversal of myoneural blockade with neostigmine causes no significant change in cerebrospinal fluid pressure.

Adrenaline-induced hypotension in neurosurgery.

We have compared the effects of scalp infiltration with 0.5% lignocaine, 0.5% lignocaine with adrenaline 1:200,000, 0.9% saline and 0.9% saline with adrenaline 1:200,000, in a prospective, randomized, double-blind study. Direct arterial pressure, heart rate and bleeding at incision were recorded in 80 patients undergoing craniotomy or craniectomy. Arterial pressure decreased by more than 20% from preinfiltration values in 40% of patients in the saline with adrenaline group, and in 55% of patients in the lignocaine with adrenaline group. It did not decrease in patients who did not receive adrenaline.

Ventilatory monitoring during microlaryngeal surgery using jet insufflation anaesthesia.

We describe a method for continuous measurement of end-tidal carbon dioxide concentration during jet insufflation anaesthesia for microlaryngeal surgery. This increases the safety of the technique by allowing closer monitoring of inspired and expired gases during anaesthesia.

Observations on deliberate dural puncture with a Tuohy needle: pressure measurements.

Pressure recordings were made during passage of a Tuohy needle from the interspinous ligament to the subarachnoid space for lumbar drain insertion. Epidural space pressures were always positive. Negative pressures were seen only at the moment of entry into the subarachnoid space. These were artefactual and were caused by tenting of the dura by the blunt Tuohy needle. Use of a closed measurement system such as this facilitates the development of large transdural pressure gradients because of the inability of the epidural space pressure to equilibrate with atmospheric pressure. This may contribute to ease of dural puncture.

Observations on deliberate dural puncture with a Tuohy needle: depth measurements.

Observations were made during the use of a Tuohy needle to perform deliberate dural puncture for the insertion of lumbar drains to improve operating conditions for intracranial aneurysm surgery. The most striking finding was the distance from identification of the epidural space to penetration of the dura. We postulate that this was because of tenting of the dura by the blunt Tuohy needle. This was facilitated by the absence of a negative epidural space pressure because an open system was used, which allowed time for pressure equilibration. This minimised the reactive forces across the dura. Aspiration and rotation of the Tuohy needle revealed dural puncture in some cases.

The myasthenic syndrome: anaesthesia in a patient treated with 3.4 diaminopyridine.

A case of anaesthesia in a patient with myasthenic syndrome treated with 3.4 diaminopyridine is described. Despite symptomatic improvement and an improved electromyogram (EMG) on treatment, extreme sensitivity to neuromuscular block occurred with vecuronium. Antagonism of block was poor with an anticholinesterase, while oral 3.4 diaminopyridine improved neuromuscular transmission further. A combination of anticholinesterase with aminopyridine may be the antagonistic combination of choice in this condition.

Lipoid proteinosis: Urbach-Wiethe disease.

An otherwise healthy patient with Urbach-Wiethe disease required surgical removal of two 3rd molar teeth. In this multisystem disorder infiltration of the buccal, pharyngeal and laryngeal mucosa may cause difficulties with tracheal intubation and increase the likelihood of trauma. The anaesthetic implications and management are described.

Effect of doxapram on postoperative oxygenation in obese patients.

A infusion of doxapram in 5% dextrose at a rate of 2 mg/kg/hour for 6 hours, or of 5% dextrose alone, was given to 20 grossly obese patients who had undergone upper abdominal surgery. There was no statistically significant difference in the degree of hypoxaemia or the incidence of chest infections between the two groups.