Anesth Analg Vol. 57, July-Aug. 1Y78

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Correspondence

Correspondence BACTERIAL FILTER RESISTANCE To the Editor: I am concerned about the data and conclusions presented by Dr. Edward Loeser in his article “Water-induced resistance in disposable respiratory-circuit bacterial filters” (Anesth Analg 57:269-271, 1978).

CURARE SENSITIVITY I N MYASTHENIA GRAVIS To the Editor:

We read with interest the case report of curare sensitivity in steroid-treated myasthenia gravis by Carol Lake.l We question Dr. Lake’s conclusion that “steroids in myDr. Loeser first contacted our company in asthenia . . . clearly do not result in suffiSeptember 1977 regarding his program for cient acetylcholine . . . to require a usual testing disposable anesthesia filters. He was dose of nondepolarizing muscle relaxant.” told at that time that we had developed, We have anesthetized a steroid-treated mywere manufacturing, and were selling a asthenic who did not show curare sensitivity. Nicholes 99 filter with a hydrophobic coat- Our patient presented in myasthenic crisis ing to prevent occlusion by water without at age 52 in 1972. The patient’s symptoms impairment of biologic filtration efficiency. were initially controlled with pyridostigmine A t this time Dr. Loeser stated that “the 180 mg per day. In April 1974, the patient K + G filter [even] without the hydropho- was started on prednisone 60 mg daily, and bic coating was safe for anesthesia usage.” the pyridostigmine was stopped. The prednisone was tapered to 20 mg on alternate Dr. Loeser offered to include the new days with minimal symptoms. In May 1977, Nicholes 99 hydrophobic filter in his test the patient, weighing 81 kg, required a Nisprogram and was provided with filters and sen fundoplication for esophagitis. Anesthesupportive data for this purpose. He never- sia was induced with thiopental IV and t heless selectively excluded the hydrophobic N,O-0,-enflurane by mask; endotracheal infilters from his study and failed to report tubation without relaxants was performed data on their function in the article cited. without difficulty. Additional relaxation reFurthermore, had Dr. Lmser employed a quired for surgery was obtained with 3-mg relative humidity more relevant to normal incremental doses of d-tubocurare given clinical conditions he would have found, as slowly over 30 minutes while hypothenar have others, even the untreated Nicholes 99 muscle twitch was monitored during ulnar filter to be fully acceptable since little or no nerve stimulation with a Block-Aid moniwater exists as a liquid in an anesthesia tor. Satisfactory relaxation and loss of circuit during clinical use. It is only present twitch required a total of 24 mg. Thirty as a vapor. minutes later another 3 mg of curare were Every Nicholes 99 filter is thoroughly in- needed. Reversal with neostigmine and atrospected and tested before shipment and pine, 45 minutes later, restored twitch and there have been over one million Nicholes sustained tetanus. In March 1978, the pa99 filters used without a single problem of tient (73 kg) , now on prednisone 30 mg occlusion having been reported. The current every other day, required reconstruction of Nicholes 99 filter is treated with a hydro- the Nissen fundoplication because of inphobic coating which acts to prevent occlu- creasing regurgitation. Following preoxygension by water but in no way impairs its ation and precurarization with 3 mg of cuunique functionality. Tests under exagger- rare, which produced no clinical weakness, ated conditions show that long-term use (up rapid induction of anesthesia was achieved to 29 hours) does not cause a drop in biolog- using 250 mg thiopental. While holding criical filtration efficiency (B.F.E.) ; nor does coid pressure, intubation was facilitated with the AP (change in pressure) increase more succinylcholine 100 mg. About 6 to 8 minthan approximately 2 mm/H,O at 100% utes following the succinylcholine adminisrelative humidity delivered at 37 C at 10 L tration, twitch returned to control values. Anesthesia was maintained with N20-0,air/min. enflurane. Abdominal relaxation required 18 Harry R. Leeds President, K & G Healthcare mg of curare initially, supplemented to a total of 30 mg over the next 3 hours. All Industries doses were given in 3- to 6-mg increments Miami, Florida 33166

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while twitch was monitored. Pyridostigmine restored twitch. While both this patient and Dr. Lake’s patients were similar in age, weight, and control of the myasthenic state with steroids, their responses to curare for relaxation were markedly different. The curare doses used in our patient are not unusual for surgical relaxation during enflurane anesthesia in normal patients, as Fogdell and Miller? have shown a reduction in the dose of curare needed during enflurane. Does curare sensitivity remain in steroid-treated myasthenies? While Dr. Lake’s patient would indicate it does, our patient failed to demonstrate sensitivity. Hopefully others will submit their experiences to clarify this issue.

R. B. Fillmore, MD Staff A. L. Herren, MD Staff A. F. Pirlo, MD Resident 1 Anesthesiology Department Naval Regional Medical Center San Diego, California 92134 REFERENCES I . 1,ake CT.: Curare sensitivity in steroid-treated myasthenia gravis: a case report. Anesth Analg 57: 1.1‘2-134, 1978 2. Fogdell R P , Miller RD: Neuromuscular efferts of enflurane, alone and combined with d-tuboiwxrine. pancuronium, and succinylcholine. in man. Anesthesiology 42: 173-178. 1975

The opinions or assertions in this letter are those o f the authors and are not to be construed as offivial or reflecting the views of the Navy Department or the Naval Service a t large. :::

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Curare sensitivity in myasthenia gravis.

Anesth Analg Vol. 57, July-Aug. 1Y78 515 Correspondence Correspondence BACTERIAL FILTER RESISTANCE To the Editor: I am concerned about the data and...
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