The position of the patient during neurosurgical procedures on the posterior fossa

Summary Different parameters were measured on patients in six different positions during infratentorial surgery. One group of data served to prove that such patients were in a steady-state as far as their cardiovascular and ventilatory function was concerned. The other measured parameters concerned the intracranial pressure, the intracranial venous pressure and the cerebral perfusion pressure. It appeared from the comparison of these data, that the lateral sitting (45°) position had important advantages and that in this position the possibility of unfavourable features (such as air-embolism) was minimized.     

Coregistered ultrasound as a neurosurgical guide

INTRODUCTION: The dynamic nature and three dimensionality of ultrasound data can be utilized to enhance the capabilities of image guidance systems. METHODS: Coregistration of ultrasound data was done using an electromagnetic digitizer, and subsequent ultrasound images were correlated with preoperative MRI studies. Thirty-two patients undergoing craniotomy were investigated in this manner. RESULTS: Phantom testing done with a rigid stylus and 3D ultrasound tracker demonstrated an accuracy of 1.36 +/- 1.67 mm in determining the location of a point. Thirty-two clinical cases were coregistered without difficulty. CONCLUSION: Coregistered ultrasound is a useful methodology that can aid in neuronavigation.     

Pentax-AWS airway Scope as an alternative for awake flexible fiberoptic intubation of a morbidly obese patient in the semi-sitting position

For anesthesia induction in a morbidly obese patient with a full stomach, awake flexible fiberoptic bronchoscope (FOB) intubation in the semi-sitting position may be a suitable choice. A new rigid indirect videolaryngoscope, the Pentax-AWS system, has a unique feature of an adjustable built-in monitor and is designed to be used in patients in various positions. However, the efficacy of its use in such situations has not been investigated or reported. We used the Pentax-AWS system for the intubation of a morbidly obese patient (body mass index >50) who was at risk of regurgitation, anticipated difficult intubation, and supine hypotensive syndrome due to inferior vena cava compression by a huge ovarian cyst. The patient was placed in the sitting position during the intubation procedure. The patient’s trachea was intubated with the Pentax-AWS by an anesthesiologist positioned at the patient’s right and facing her. The Pentax-AWS offered easy intubation under good visualization of the glottic aperture as a consequence of its adjustable integrated monitor, in contrast to difficult intubation with other videolaryngoscopes which require an external monitor. This report illustrates that the Pentax-AWS is useful as an alternative for flexible fiberoptic intubation under these circumstances, as a consequence of its adjustable built-in monitor and integrated tube channel.     

Preoperative and intraoperative echocardiography to detect right-to-left shunt in patients undergoing neurosurgical procedures in the sitting position

In patients undergoing neurosurgical procedures at high risk for venous air embolism (VAE), the presence of a right-to-left shunt adds an additional risk for paradoxical air embolism (PAE). Although this is a rare complication, it can have devastating results. The most common form of right-to-left shunt is a patient foramen ovale (PFO), which can be detected by contrast echocardiography. This study evaluates the efficacy of preoperative precordial and intraoperative transesophageal echocardiography (TEE) to detect right-to-left shunting in patients undergoing neurosurgical procedures while in the sitting position. In 101 patients precordial contrast echocardiography was performed prior to surgery. The Valsalva maneuver was utilized as a provocative maneuver to facilitate demonstration of right-to-left shunting. Fifty-one of these patients also had intraoperative TEE monitoring. Right-to-left shunting was demonstrated in only six of the 101 patients examined. Of these, four were detected by TEE. This is less than the expected incidence based on the known incidence of PFO in the general population. The usefulness of preoperative ECHO as a screening test for PFO in patients undergoing neurosurgical procedures is limited, but when a PFO is found, valuable information is acquired to help manage these patients.     

Improved patient positioning for percutaneous nephroscopic procedures using a surgical saddle

PURPOSE: We describe modified patient positioning on the Cloward surgical saddle for use during percutaneous nephroscopic procedures. MATERIALS AND METHODS: The Cloward surgical saddle, which was designed for prone patient positioning, has been used primarily for lumbar surgery. We evaluated the use of the surgical saddle for ease of patient positioning during percutaneous nephroscopic procedures. RESULTS: We have used the surgical saddle in 10 patients to date, including 1 who was 5 feet 8 inches (173 cm.) tall and who weighed 370 pounds (168 kg.). In all cases pulmonary airway pressure was maintained at less than 30 cm. water. We have observed no incidence of pressure injury or other complications associated with position. CONCLUSIONS: Patient positioning during percutaneous nephroscopic surgery is important for preventing pressure injury and allowing adequate pulmonary ventilation. The surgical saddle is an excellent aid for secure patient positioning during percutaneous nephroscopic procedures that helps to minimize the risk of pressure injury and pulmonary compromise.     

Case of awake intubation in semi-sitting position for a patient with myasthenia gravis combined with cervical disc hernia utilizing Pentax-AWS Airwayscope

We report a case of awake intubation utilizing Pentax-AWS Airwayscope in semi-sitting position. A 74-year-old man with myasthenia gravis and cervical disc hernia was scheduled for distal gastrectomy under general anesthesia. He could not move his head due to severe cervical disc hernia and also could not sufficiently breathe due to the fatigue of respiratory muscles by myasthenia gravis in supine position. With fentanyl bolus administration and lidocaine spray for laryngotracheal anesthesia, we performed awake intubation in semi-sitting position with AWS from cranial side. The patient did not buck during intubation and no hemodynamic change was observed.     

Perioperative considerations for neurosurgical procedures in the gravid patient: Continuing Professional Development

Purpose

The complexity of neurosurgical procedures and their interactions with maternal and fetal physiologies are key factors in determining the overall maternal and fetal outcome. The literature and guidelines provide only partial information regarding the standard of care in these cases. The purpose of this Continuing Professional Development module is to review the issues related to common neurosurgical conditions and their optimal anesthetic management.

Principal findings

The most common neurosurgical conditions found in pregnancy include brain tumours, cerebrovascular diseases, spinal pathologies, and neurotrauma. Though rare, these conditions and related procedures may affect maternal and fetal outcome. Maternal considerations should be given priority in cases of emergent surgeries irrespective of trimester. In the early first trimester, risk of fetal loss and congenital malformation are substantial; hence, proper counselling should be given to the mother with special emphasis on therapeutic abortion. When indicated, anticonvulsants should be started as early as possible and continued throughout pregnancy. Surgical procedures can be performed with relative safety during the second trimester and early third trimester. After 34 weeks, delivery seems to be the first choice, and the role of regional anesthesia in this situation should be carefully planned after proper review of neurosurgical pathology and maternal condition. During acute neurological deterioration, however, Cesarean delivery under general anesthesia should be anticipated.

Conclusion

A multidisciplinary approach with good communication amongst all team members certainly plays a crucial role for successful management of such cases.     

Transesophageal echocardiography for cardiac surgery in children

OBJECTIVE: To evaluate the usefulness of transesophageal echocardiography (TEE) for cardiac surgery in children. DESIGN: Prospective clinical study. SETTING: Nagoya City University Hospital. PARTICIPANTS: Children who had cardiac surgery from January 1998 to December 2000 (n = 90). INTERVENTIONS: TEE was used to the extent permitted by the probe size and the position of the patient during surgery. MEASUREMENTS AND MAIN RESULTS: TEE monitoring was performed safely without any complications in 88 of the patients. Based on the TEE findings, the anesthesiologists conferred with the surgeon about the efficacy of the surgical procedures in 11 patients (11 of 88 [12.5%]). The cardiac surgeons altered the surgical repair in 2 patients based on the TEE findings (2 of 88 [2.4%]). CONCLUSION: TEE is a valuable diagnostic tool for monitoring during cardiac surgery in children. The person who performs the TEE should use it carefully after obtaining thorough knowledge of the pathophysiology of pediatric cardiac diseases, their surgical indications, and how specific surgical procedures are done.     

Method of determining kidney position as guide for percutaneous nephrostomy

Computed tomography scans were used to assess the distance between the skin and the collecting system in 256 kidneys in 128 adult patients of various heights and weights. Body surface area correlated well with kidney depth. A graph is presented that can be used to calculate kidney depth.     

Effects of the sitting position on the distribution of blood volume in patients undergoing neurosurgical procedures

The use of the sitting position in neurosurgery is often associated with decreased arterial pressure (MAP) and stroke volume index (SVI). A shift in blood from the intra- to the extrathoracic compartment may be responsible for this cardiovascular response. However, little is known of the amount of shift in blood volume after transfer from the supine to the sitting position. Therefore, we measured simultaneously changes in intrathoracic blood volume (ITBV) caused by a change in body position in anaesthetized patients. Measurements of cardiac index (CI), ITBV, pulmonary (PBV) and total circulating (TBVcirc) blood volumes were performed in the supine and sitting position. CI, ITBV, PBV and TBVcirc were measured using a thermodye dilution technique. Fluid input was restricted to 14 ml kg-1 before induction of anaesthesia. Change in body position caused a significant decrease in ITBV and was accompanied by a significant decrease in CI, SVI and MAP. Changes in ITBV correlated (r = 0.78) with changes in SVI. Thus a change in blood volume distribution between the intra- and extrathoracic compartment occurred after a change from the supine to the sitting position. Indicator dilution enables quantification of this shift and may be helpful in guiding fluid therapy in selected patients.      

Frameless localization for functional neurosurgical procedures: a preliminary accuracy study

BACKGROUND: Targeting for functional stereotactic procedures is traditionally carried out in a noninteractive fashion, without real-time positional feedback. In addition, stereotactic frames are uncomfortable for patients and may impede intraoperative neurological evaluation. As an initial step toward a fully frameless approach to functional surgery, we have investigated the use of an image-guided microdrive coupled to a stereotactic frame system. METHODS: For initial laboratory tests, a stereotactic phantom was imaged using high-resolution CT scanning. Three representative targets were chosen within the phantom. Targeting was carried out in the usual fashion using the StealthStation planning suite, utilizing the Radionics CRW system. An LED-equipped reference arc was attached to the CRW base ring. Registration of the base ring was accomplished using a spherical probe. A custom-built microdrive was fitted with an LED array, mounted on the CRW arc and tracked by the StealthStation. The distance between the Stealth real-time localization and the CRW localization was measured on-screen. To evaluate the accuracy of the system in the operating room, a similar procedure was carried out in 13 functional neurosurgical operations (pallidotomy or deep brain stimulator placement). RESULTS: Errors of localization in the laboratory setting ranged from 0.53 to 0.70 mm. In 11 operative cases, the average difference between the CRW localization and the Stealth localization was 1.77 mm. In the remaining 2 cases, equipment malfunction prevented measurement of localization error. CONCLUSIONS: Frameless image-guided localization compares favorably to targeting performed noninteractively. In addition, real-time positional feedback confers advantages in target region visualization and confidence in placement of lesions and stimulators for functional procedures. With small improvements in accuracy and system reliability, fully frameless functional procedures could be safely carried out.