Current-conveyor-based wide-band current driver for electrical impedance tomography.

OBJECTIVE: In this paper a wide-band integrated current driver for electrical impedance tomography (EIT) is presented. The application is primarily for prostate and breast cancer detection which require the tissue to be interrogated at frequencies up to 10 MHz while achieving low harmonic distortion and high accuracy. APPROACH: The current driver is based on current conveyor architecture and can deliver 1.2 mA of peak to peak ac current between frequencies of 100 Hz-10 MHz. It is fabricated in CMOS 0.18 [Formula: see text]m technology with a power supply of 3.3 V, and occupies a core area of 0.26 [Formula: see text]. MAIN RESULTS: The measured harmonic distortion for a peak current of 1.2 mA is <[Formula: see text] for frequencies less than 100 kHz, and increases to [Formula: see text] at 10 MHz. The measured output impedance of the current driver is 101 k[Formula: see text] at 1 MHz and 19.5 k[Formula: see text] at 10 MHz. SIGNIFICANCE: The circuit is suitable for high frequency active electrode applications.

Reconstructions of conductive and insulating targets using the D-bar method on an elliptical domain.

The D-bar algorithm based on A Nachman's 2D global uniqueness proof for the inverse conductivity problem (Nachman 1996 Ann. Math. 143 71-96) is implemented on an elliptical domain. The scattering transform is computed on an ellipse and the complete electrode model (CEM) for the forward problem is computed with the finite element method (FEM) in order to obtain static conductivity reconstructions of conductive and insulating targets in a saline-filled tank. It is demonstrated that the spatial artifacts in the image are significantly reduced when the domain is properly modeled in the reconstruction, as opposed to being modeled as a disk.

Corticotropin-releasing hormone receptor blockade fails to alter stress-evoked catecholamine release in prefrontal cortex of control or chronically stressed rats.

Although it is well documented that stress can increase the activity of central dopamine and norepinephrine neurons, little is known about the role of other neurotransmitters in modulating this response. Previous studies have implicated corticotropin-releasing hormone in modulating stress-evoked changes in the activity of locus coeruleus neurons. The present study examines whether corticotropin-releasing hormone contributes to stress-evoked increases in extracellular norepinephrine and dopamine in rat medial prefrontal cortex, as monitored by in vivo microdialysis. As noted previously, 30 min of tail-shock increased extracellular levels of norepinephrine and dopamine in the medial prefrontal cortex of naïve rats, and this was enhanced in rats previously exposed to chronic cold ( approximately 5 degrees C for 2-3 weeks). Previous intraventricular administration of a corticotropin-releasing hormone antagonist (D-Phe-corticotropin-releasing hormone; 3 and 9 microg) did not alter the tail-shock evoked in increase in extracellular levels of norepinephrine and dopamine in either naïve or chronically cold-exposed rats. Intraventricular administration of 3 microg of D-Phe-corticotropin-releasing hormone attenuated the increase in extracellular norepinephrine induced by co-administration of 3 microg of corticotropin-releasing hormone, confirming the efficacy of this compound. Results of the present study suggest that endogenous corticotropin-releasing hormone does not play a role in modulating the release of norepinephrine and dopamine occurring in response to acute tail-shock or the expression of a potentiated response to tail-shock in rats exposed chronically to cold.

Corticotropin-releasing hormone (CRH) expression and protein kinase A mediated CRH receptor signalling in an immortalized hypothalamic cell line.

Corticotropin-releasing hormone (CRH) is a 41 amino acid neuropeptide which plays an important role in the stress response in the hypothalamus. We describe the development of an immortalized hypothalamic cell line which expresses CRH. We hypothesized that this cell line would possess the relevant characteristics of parvocellular CRH-expressing neurones such as glucocorticoid receptor (GR) expression and vasopressin (VP) coexpression. For production of hypothalamic cells, embryonic day 19 rat pup hypothalami were dissected and dissociated into tissue culture dishes. They were immortalized by retrovirus-mediated transfer of the SV40 large T antigen gene at 3 days of culture and then screened for expression of CRH following dilution cloning. One cell line was chosen (IVB) which exhibited CRH-like immunoreactivity (CRH-LI) and expressed CRH, VP and CRH1 receptor RNA via the reverse transcriptase-polymerase chain reaction. In addition, the cell line expressed the neuronal marker, microtubule-associated protein-2. We verified that the CRH-LI from IVB cell lysates coeluted with CRH standard via reversed-phase high-performance liquid chromatography (HPLC). Furthermore, oxidation of the lysate converted its HPLC profile to that identical with oxidized CRH standard. In addition, IVB cells exhibited high affinity binding to CRH. Incubation of IVB cells with CRH lead to increases in cAMP levels and protein kinase A activity in a concentration-dependent manner. Incubation of IVB cells with CRH also resulted in increases in phospho-cyclic-AMP response element binding protein (CREB) immunostaining as detected by immunocytochemical analysis. Finally, CRH treatment of IVB cell lines has been linked to CREB-mediated gene expression as determined via the PathDetect CREB trans-reporting system. The characteristics of IVB cells, such as CRH and VP coexpression, GR expression and a biologically active CRH-R1-mediated signalling pathway, suggest that this neuronal cell line may serve as model of parvocellular CRH neurones.

The effect of shortened statutes of limitations on nurses.

These cases illustrate the need for nurses to closely monitor the various tort reform legislation initiatives in all states. Many tort reform proposals are intended to reduce the liability exposure of physicians and hospitals. In doing so, these proposals may inadvertently increase the nurses' exposure. Nurses must monitor tort reform proposals before they are passed into law because they may cause a disproportionate impact on nurses. Nurses also need to lobby for amendments to existing statutes that do not protect nurses.

Informed consent: Part III.

Perioperative nurses are concerned about their patients understanding the procedures they will undergo. The legal system agrees that patients have the right to be informed about and consent to surgical procedures; informed consent is a legal right. No state, however, has recognized a formal role for the perioperative nurse in the enforcement of this right. Case law has consistently found that the necessary interchange for informed consent is vested in the patient-physician relationship, and it views broadening this legal responsibility as more disruptive than beneficial. When everyone is responsible, it is more difficult to ensure that someone actually talks to the patient. Present law makes that someone the surgeon. The role of the perioperative nurse includes informing the surgeon if the patient's informed consent has not been documented in accordance with agency policy, documenting having done so, and taking any additional actions required by agency policy. Perioperative nurses who suspect overreaching by surgeons should inform their administrators. The perioperative nurse should not unilaterally get involved in the physician-patient relationship. The patient has sought the services of the surgeon, not the nurse.

Informed consent: Part II.

Although the legal responsibility to inform and obtain the patient's consent lies with the surgeon, the agency may have a duty to ensure that the patient's consent has been obtained. Agency liability is limited to those cases in which the agency knew (or should have known) that informed consent was not obtained. It is still unclear whether agencies have an affirmative duty to ensure that consent has been obtained. If this duty does exist, it appears that a policy requiring documentation in the medical record of the patient's consent meets this requirement. It is clear that whatever the extent of the agency's duty, it does not include the duty to give the patient information or assess his or her level of understanding. Court opinions discourage anyone but the physician from doing so. A nurse's legal responsibility is limited to following agency policy. Courts have not recognized any independent nurse duty beyond that which accrues to them as employees of the agency. Perioperative nurses often provide the final checkpoint that consent has been obtained and documented before the procedure begins. This unique position raises additional legal concerns if the agency's policy is not followed or if the premedicated patient arrives without proper consent documentation in the record. Perioperative nursing concerns will be discussed next month in Part III.

Issues regarding parents in the operating room during their children's care.

The presence of parents in the operating room does have possible legal ramifications. Taking an upset child from a parent's arms, however, is not a positive situation either. Perioperative nurses should not automatically weigh legal implications more heavily than the patient benefit that may be derived from the presence of parents. Whether parents should or should not be allowed to accompany their children into the operating room should be a carefully considered institutional policy.

Preventing a successful malpractice claim.

All of these strategies combine to make it less likely that a suit will be filed. But the strategies of complying with the standard of care and accurately documenting that care also combine to make it less likely that a suit will be successful. Injury is just one element of a successful malpractice suit. The plaintiff's attorney must also convince the judge or jury that the defendant failed to meet the standard of care and that failure caused the patient's injury. By complying with the standards of care and documenting that care, the nurse makes it easier for his or her attorney to counter arguments that the standard of care was not met. Accurate documentation can also fortify arguments that the nurse's actions did not cause the injury. There is nothing magical about these five strategies. Nurses will recognize each as actions good nurses perform in the course of their practice. Providing good nursing care also provides the best legal protection.

Individual malpractice insurance decisions revisited.

Nurses' professional obligations to their patients include financial accountability. Whether nurses best provide this through self-insurance, coverage by an employer's insurance policy, or by purchase of an individual policy remains a personal decision. Changes in law and the health care market, however, should prompt a revisiting of this decision because the relative costs and benefits of each option may have changed. The pace of these changes, the unexpected consequences of some of the legal changes, and the individual differences in each nurse's situation may require seeking legal counsel to identify and evaluate the risk/benefits in that situation. The cost of that counsel may well exceed the cost of the policy premium.

Incident reports may or may not be privileged information.

Whether incident reports are discoverable depends on the purpose of the reports and the laws of the state where the reports are filed. Subtle differences in state laws and/or how reports are used can make major differences in the determination. These differences are for hospital attorneys to study and consider. In addition to anticipating litigation, hospitals may use incident reports to promote hospital safety and prevent general losses. The hospital, not the nurse, decides if incident reports will be used in a manner more likely to protect the reports from discovery or if protection from discovery is of less concern (either because of state law or corporate philosophy). These decisions will determine how the forms are printed, when reports should be filed, what information is required, how many copies are made, and to whom the copies are distributed. Perioperative nurses need only follow the facility's policy and procedure for completing and filing incident reports. If the hospital attempts to protect reports from discovery, it is especially important that the procedure be followed precisely.

The expert nurse witness.

The expert nurse witness plays a necessary role in our civil system. Although the prospect of serving as an expert witness may seem onerous, OR nurses should give serious thought to doing so. If practicing OR nurses do not testify, attorneys may have to rely on physicians or non-OR nurses to testify to OR nursing standards. As professionals who want to establish and uphold professional standards, OR nurses should consider serving as expert witnesses to assist the court in establishing the legal standards of OR nursing practice.

The many faces of the liability insurance crisis.

The purpose of this column is to provide an overview of some of the issues and arguments encompassed in the liability insurance crisis, and to impress upon nurses that they can no longer view them as relevant to physicians and hospitals only. This brief overview cannot cover all you need to know before making decisions about insurance or forming strategies to address your state regulations. It is intended to provide you with an impetus to work within your state nurses' association to learn more.

Can the RN first assistant be held liable for patient injury?

In summary, if an action of the RN first assistant causes a patient injury, both the primary surgeon and the RN first assistant could be liable. The primary surgeon could be liable for failure to see that the operation was performed with due care. At least one state appellate court has found that this is a nondelegable duty of the primary surgeon. The RN first assistant could be liable if the action that caused the patient injury was not in accordance with what a reasonable and prudent first assistant would have done. If first assisting is included within the scope of nursing practice by rule or statute in that state, the RN first assistant action could be measured against what an RN first assistant would have done, even though first assisting has traditionally been a physician's role. The fact that first assisting may be within the scope of nursing practice for some procedures and patient conditions does not mean the nurse should be allowed to assist on all procedures or in all patient conditions. The institution may have an independent duty to its patients to determine which patient procedures and conditions are appropriate for an RN first assistant.

"Captain of the ship" doctrine continues to take on water.

The captain of the ship doctrine, which has been interpreted to mean that the surgeon's mere presence in the OR subjects him or her to legal liability for everyone's negligence in that room (akin to the responsibility of the captain of a ship who is held responsible for everything that happens on that ship), emerged in 1949 and grew in popularity through the 1950s. The major reason for this doctrine's popularity was that injured patients were precluded from suing hospitals under the then applicable charitable immunity doctrine. Charitable immunity declined in the 1960s, and by the 1970s, so too was the captain of the ship doctrine in decline. Pennsylvania, which first used the picturesque phrase in 1949, rejected the doctrine in 1974. In the meantime, it has come under much criticism, even among states that adopted it. Despite this decline and despite court language that sometimes borders on ridicule (e.g., anachronistic, prostrate doctrine, indiscriminate repetition), the felicity of the phrase has kept it alive in some states and in many ORs, even in states that have expressly rejected the doctrine. Even more than 20 years after its first rejection, however, courts still are being asked to adopt the doctrine. In 2001, the Wisconsin Supreme Court declined to adopt the doctrine, adding to the litany of states that have taken an express position against it.

Monitoring i.v. conscious sedation, the legal scope of practice.

Registered nurses who are not CRNAs and are undertaking the administration and/or monitoring of patients receiving IV conscious sedation should consult their state board of nursing, undertake and document the additional education or training to monitor IV conscious sedation patients safety and document the successful achievement of competency in these services, and work with nursing, surgery, and anesthesia staff members to develop written protocols and policies. Written policies must include the provisions, if any, as prescribed by the state's board of nursing. The provisions of other state boards of nursing could be considered for possible inclusion. Policies should reflect nursing practice as described in the professional literature. Professional association position statements, such as those issued by the ANA and endorsed by AORN and other specialty associations and those issued by AANA, should be consulted. AORN's "Recommended practices for monitoring patients receiving intravenous conscious sedation" in the 1993 edition of AORN Standards and Recommended Practices for Perioperative Nursing should be incorporated into the institution policy as appropriate.