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Departments of Anesthesiology, Neurosurgery, and Plastic and Reconstructive Surgery, Wake Forest University School of Medicine, Winston-Salem, North Carolina
Address correspondence to Douglas G. Ririe, MD, Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1009. Address e-mail to dririe{at}wfubmc.edu
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Abstract |
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IMPLICATIONS: This study compares the perioperative management of two different surgical procedures for the repair of sagittal craniosynostosis. Progress in surgical technique results in differences in perioperative care that directly impact anesthetic management.
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Introduction |
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Advances in craniofacial surgery have progressed with the implementation of different surgical techniques (1–5). Some of these have relied on advances in technology and include the use of improved imaging techniques as well as the use of endoscopic devices, which have also had an impact on reducing blood transfusion (3,5). However, the more limited techniques used for achieving good cosmetic results are not as effective as originally thought (6,7).
More recently, spring-mediated craniofacial reshaping has been reported (4). The use of this intervention has recently been expanded to include evaluation of its use in the management of children with sagittal suture craniosynostosis. At our institution, we have been involved in a trial of spring-mediated craniofacial reshaping for sagittal synostosis by the pediatric neurosurgeons and plastic surgeons. We hypothesized that this innovation in management would have a significant impact on the perioperative management of these children. As a result, we have compared two craniofacial reshaping surgical techniques, the recent development of spring-mediated expansion (SME) versus conventional cranial vault reconstruction (CVR), and studied the impact on perioperative anesthesia care.
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Methods |
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Nine patients underwent general anesthesia for the SME procedure, requiring sagittal strip craniectomy and placement of a spring device. Four to six months (mean, 4.2 mo) later, these same patients underwent a second general anesthetic for removal of the spring devices. The perioperative impact of the change in the surgical procedure was compared with a second group of eight children with sagittal suture synostosis undergoing a standard CVR procedure. All procedures were performed by a single pediatric neurosurgeon and a single pediatric plastic surgeon during a 12-mo period.
The two procedures are briefly described. The SME procedure was performed by removing a 0.8-cm strip of midline calvaria, including the sagittal suture. After this limited craniectomy, two 1.2-mm thick stainless steel omega shaped expanders (springs) were placed. At the second operation, two small incisions were made to expose the ends of the steel springs that were then removed. The CVR procedure was performed by standard craniectomy followed by expansion using a series of progressive tongue-and-groove extensions of the cranium, as previously described (8).
General transfusion guidelines used for these patients were a hematocrit <21 or a hematocrit <26 if continuing significant blood loss was present or hemodynamic instability related to intravascular volume was present. Once a unit was started, blood was used to replace intravascular volume loss-deficit to a hematocrit of 35 with the same unit. To transfuse a patient with a second unit of blood, the original guidelines were again used.
All perioperative data were collected from the charts in a retrospective manner. The information was noted as follows: age, weight, baseline hematocrit, type of surgical repair, anesthesia time, and surgical time. Data from the anesthesia record were also obtained as to monitors used, crystalloid, colloid and blood products administered (mL), estimated blood loss (EBL), vital signs, respiratory variables, position, and laboratory values, as documented in the record. Episodes of hypotension were also assessed as blood pressure <20% less than baseline as written on the record. Postoperative data were also collected from the postanesthesia care unit and during the hospital stay.
The CVR procedure was compared with the initial SME procedure and also compared with the combined blood loss, transfusion, anesthesia time, surgical time, and length of stay for the insertion and the removal of the cranial springs in the SME group. Anesthesia time was taken from the anesthesia record and signified the time the patient entered the room until the time the patient was in the postanesthesia care unit and no longer under the direct care of the anesthesiologist. Surgical time was also taken from the anesthesia record and was considered the time from the beginning of preparation for the surgery until the dressing was in place. Length of stay in the hospital was taken as the number of days the patient was in the hospital after the day of surgery. Intensive care unit (ICU) days were measured in overnight 24-h periods.
Data are presented as mean with the 95% confidence interval in parentheses except where the range is stated. These data were analyzed using the t-test with a Satterthwaite correction for unequal variance.
Results
A total of 17 children were entered into the study with a known diagnosis of scaphocephaly secondary to sagittal synostosis based on computed tomography imaging scans as well as clinical examination findings. Nine of the children underwent repair using craniectomy and spring placement for SME and then removal. Eight underwent repair of CVR. Demographics are presented in Table 1.
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There was no difference for anesthesia time between the CVR group and the combined SME procedures (Table 2). Anesthesia time for the insertion SME was 2 h 40 min and 1 h 48 min for SME removal. Surgical time for the CVR procedure was longer than the combined SME. The average surgical time for the insertion SME was 1 h 21 min and 1 h 0 min for the removal SME.
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The average hospital stay and ICU time was longer in the CVR group (Table 2). The average length of stay for the insertion SME was 2.1 days (range, 2–3 days), whereas the length of stay for the removal SME was 1 day. No patient in either of the SME surgery groups, insertion or removal of the springs, was admitted to the ICU. In all patients, the trachea was extubated at the conclusion of every procedure. No patient required reintubation.
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Discussion |
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In this study, the patients undergoing SME were younger and smaller than those undergoing the CVR surgery. The current IRB protocol for SME is only available to children younger than seven months of age based on the early unpublished clinical results demonstrated by the Swedish craniofacial team. Children older than seven months are not eligible for this IRB protocol at this time. Selection criteria were based solely on the age at the time of presentation to the surgeon. Previous studies have demonstrated that the percentage of blood volume loss is larger in the younger, smaller patients for a given procedure (11). Although the SME patients were smaller and younger, EBL was still more in the CVR group, making this finding even more impressive. It is also important to realize that earlier intervention may make the defect easier to correct and prevent physiologic or psychologic sequelae from lack of correction (12–14).
Strip craniectomy has been used in the younger age group for sagittal synostosis. However, as mentioned previously, the cosmetic outcome of strip craniectomy does not seem to be as good as either CVR or the SME (6,7,10). The anesthetic and perioperative impact of strip craniectomy demonstrates a reduction in blood loss when compared with CVR (10). This reduction of blood loss in strip craniotomy is significant when compared with CVR, but a significant number of patients undergoing strip craniectomy still require a blood transfusion. In our study, the average EBL for the CVR group of 291 mL, or approximately 41% of the EBV, is comparable to the blood loss reported for sagittal suture procedures of anywhere from 20% to 170% of EBV (11,15–17). Further advancement in technology through endoscopic strip craniectomy has resulted in even less blood loss and further reduced blood transfusion (5). In endoscopic strip craniectomy, the reported EBV loss of 1%–27% was much less than previous reports. In that study, 1 of 61 patients required intraoperative blood transfusion, and 9 of 61 required postoperative blood transfusion for endoscopic strip craniectomy. This compares with an EBV loss in the SME procedure of 2%–12% with no patients requiring transfusion.
Somewhat paradoxically, the hematocrit on postoperative Day 1 was larger in the CVR group despite more blood loss. This can be explained by two factors. First, the CVR group may have been more likely to be transfused from the beginning. Whereas the mean starting hematocrit was not significant between groups, the CVR group had a wider range of preoperative hematocrits, and one patient had a hematocrit of 27. However, the differences in blood loss and blood volume replacement limit this influence either on postoperative hematocrit or differences in transfusion. Second, the transfusion guidelines used in these patients allowed the patient to be transfused to a higher hematocrit if using the same unit for volume replacement. With these considerations, the differences in postoperative hematocrit are easily reconciled.
Blood loss data are gross estimates from the anesthesiology records for these procedures, which were collected in a retrospective review. However, an experienced physician’s intraoperative clinical assessment based on hematocrit, arterial blood gas measurement and hemodynamic alterations, including arterial line waveform analysis, is reasonably reliable. All providers in these cases were experienced pediatric anesthesiologists. Nevertheless, even under the best of circumstances, it is difficult to estimate actual blood loss during craniofacial cases in small children. The discrepancy in actual blood loss may explain the increased PT in two of the patients in the ICU. Previous studies suggest that 1–1.5 blood volumes are required to see an increase in PT (18). In the two patients whose PT was increased, the EBL was approximately 50% of a blood volume. This is considerably less than the amount usually required and suggests the actual blood loss in these two patients may have been underestimated. If so, the blood loss in the CVR group would have been even larger.
Doppler use was sporadic in the management of these patients despite the well-known problems related to venous air embolism in such cases (19–21). Many have relied on the value of the arterial line in providing immediate hemodynamic information in conjunction with the use of capnography for detection of venous air embolism (22). Experience with management of patients undergoing any procedure for craniosynostosis has made us reluctant to proceed in the absence of invasive pressure monitoring and adequate IV access, a practice supported by others (23–25). However, the impact of the SME technique has led us to reevaluate the need for invasive pressure monitoring, Foley catheter placement, and Doppler monitoring in these patients. We now proceed with SME without arterial access unless there is another indication for its use other than hemodynamic monitoring. We also no longer use a Foley catheter. We also now use routine Doppler monitoring for venous air embolism and hope to evaluate the incidence of venous air in these patients in the future. These modifications in anesthesia care result from the impact of the change in the surgical procedure and will also reduce the intraoperative time further for SME.
Whereas the total time for the combined SME procedures is less compared with the CVR procedures, the similarity in anesthesia times seems incongruous. However, anesthesia procedures all take time, and the need to repeat them in another procedure extends anesthesia time. Whereas there is a theoretical increase in risk of adverse events related to anesthesia from two exposures when compared with one exposure, this is difficult to assess. Empirically, the risk is increased with two anesthetics, as in the SME group. However, the reduced allogeneic blood exposure, invasive monitoring, and fluid shifts would seem to negate the theoretical risk of two anesthetics.
Because of the problems related to blood transfusion, methods that reduce blood loss are highly advantageous but cumbersome, particularly in small children (26). Infectious as well as other transfusion-related problems are not trivial should they occur from exposure to blood products (27–29). The change in surgical technique presented in this article clearly reduces blood exposure and therefore the risk of transfusion in these patients. Although the clinical efficacy of SME is currently being monitored with serial cephalometric measurements, early data suggest that it compares favorably with the standard of CVR for correction of sagittal craniosynostosis. As a result, it is important to be aware of these changes in surgical treatment options because they are likely to have a significant impact on perioperative management of patients.
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Acknowledgments |
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References |
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This article has been cited by other articles:
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  D. G. Ririe, P. E. Lantz, S. S. Glazier, and L. C. Argenta Transfusion-Related Acute Lung Injury in an Infant During Craniofacial Surgery Anesth. Analg., October 1, 2005; 101(4): 1003 - 1006. [Abstract] [Full Text] [PDF]
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