Anesth Analg 2002;94:233-234
© 2002 International Anesthesia Research Society
LETTERS TO THE EDITOR
Is it Ethically Correct to Study the Quincke Spinal Needle in Obstetric Patients?
Christopher MB Heard, MBChB FRCA, and
James E. Fletcher, MBBS MRCP, FRCA
The Children’s Hospital of Buffalo, Buffalo, New York
University of North Carolina, Chapel Hill, North Carolina
To the Editor: We read with interest the study (1) comparing the incidence of postdural puncture headache (PDPH) and the need for epidural blood patch (EBP) between several different spinal needles. We question the need to include a spinal needle known to carry a high risk of PDPH in obstetric patients. Using the authors’ own citations regarding the 25-gauge Quincke spinal needle, it has been established that a PDPH rate of 1 in 13 patients would be expected. Of these patients, approximately 67% will require an EBP—1 in 20 of patients subjected to the Quincke needle. That is 10 times the EBP rate known to occur after use of a pencil-point needle. The morbidity of these symptoms and their treatment should not be underestimated in the postpartum population.
Patients were told that they had <5% chance of a PDPH, without comment on the need for blood patching. We believe that patients should have been told that if randomized to the Quincke group, that they would be expected to have a PDPH risk at least three times that of current practice, and an EBP rate 10 times that which occurs in normal obstetric practice. In the absence of this information we believe the patients could not give adequate informed consent.
Two other issues also arise from this study. First, were patients required to pay for their EBP as a result of entering the study and being randomized to the Quincke group? Second, the fact that more staff anesthesiologists performed the spinal anesthetic with the Quincke needle than with the other needles negates any conclusion that can be drawn about the Quincke needle in relation to the others studied. Were the staff anesthesiologists themselves unhappy with the study design, as may be inferred by the authors comments?
We understand that it is satisfying to try and produce the "definitive" comparison of spinal needles, and that it is also of statistical benefit to include a group that can be anticipated to show a statistically significant difference to the other groups studied. However, we doubt that a study can be ethical if it exposes patients to a known increased risk of morbidity without their fully informed consent and if the design is not adequately controlled to eliminate the bias introduced by staff anesthesiologists performing more punctures with the Quincke needle than other needles.
We feel that there is little to be gained, and much to be lost from research that involves the use of the 25-gauge Quincke needle in the obstetric population.
References
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Vallejo MC, Mandell GL, Sabo DP, Ramanathan S. Postdural puncture headache: a randomized comparison of five spinal needles in obstetric patients. Anesth Analg 2000; 91: 916–20.[Abstract/Free Full Text]
Response
Manuel C. Vallejo, MD,
Gordon L. Mandell, MD, and
Sivam Ramanathan, MD
Magee-Womens Hospital, Department of Anesthesiology, Pittsburgh, PA
In Response: We appreciate the letter questioning whether it is ethically correct to study the Quincke spinal needle in obstetric patients. The intent of our study was to compare the postdural puncture headache (PDPH) incidences and epidural blood patch (EBP) rates after the use of five different commonly used spinal needles in a busy teaching obstetrical hospital. Additionally, we wanted to justify the cost in using the more expensive pencil-point needles compared with the conventional (Quincke-type) cutting-point needles (1).
It was not unethical or immoral to study the 25-gauge Quincke needle as at the time of the study, it was commonly used in obstetric anesthesia. In addition, the frequent EBP rates associated with the cutting needles was not known at the time of the study. Furthermore, the IRB approved the study.
The PDPH incidence for the 25-gauge Quincke needle in our study was 8.7%, which is comparable to the incidence of 4.5%-8.5% quoted in our paper before the study was undertaken (1). To our knowledge, this is the first study comparing the EBP rates of five spinal needles (cutting- and pencil-point) in a prospective, blinded, randomized fashion. Although the Quincke needle has a lower cost, we now recommend only using pencil-point needles for subarachnoid anesthesia in obstetric patients because of the high EBP and PDPH rates associated with cutting-point needles (1).
Patients had adequate informed consent because they were told there was approximately a 5% chance of PDPH as well as the possibility of an epidural blood patch if they did indeed get a PDPH. Patients were not required to pay for an EBP. We believe that the fact that more staff anesthesiologists performed the spinal anesthetic with the Quincke needle was a result of random occurrence. Bias is minimal because the significance in operator training level comes only with comparison to the first year clinical anesthesia (CA-1) trainees and not the second- and third-year trainees (CA-2, CA-3). There are no differences in the percentage of CA-1 trainees who performed subarachnoid blocks among the five spinal needles studied (1).
Because of the results and conclusions drawn from this study, we also feel there is little to be gained and much to be lost in additional studies comparing cutting-point needles (Quincke-type) to pencil-point spinal needles in the obstetric population.
References
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Vallejo MC, Mandell GL, Sabo DP, Ramanathan S. Postdural puncture headache: a randomized comparison of five spinal needles in obstetric patients. Anesth Analg 2000;91:916–20.
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