Spring 2006 Articles:
Epidural Analgesia - Applying The Gold StandardAuthor: Dr Karen Stuart-Smith, Consultant Anaesthetist, Glan Clwyd Hospital, Denbighshire, Wales.
The problem with epidural analgesia for peri-operative pain relief is that while its benefits seem intrinsically obvious, proving them in practice has been a difficult and elusive task. This problem is compounded by the mysticism with which other medical specialities view placement of epidurals - only anaesthetists can perform this curious ritual, and the epidural catheter disappears into a ‘potential’ space that can’t be seen.
The concept that the catheter is placed ‘close to the spine’ causes a chill in the hearts of junior surgical and nursing staff (not to mention some consultant surgeons as well). Most of us anaesthetists have had the disheartening experience of finding a carefully placed and working epidural switched off in the ward because the blood pressure is low, whereas careful assessment of the patient would have revealed that the real cause of the hypotension is inadequate fluid replacement. The result is a hypotensive patient with a low urine output who is also in severe pain. In addition they are nauseous and drowsy as a result of rescue doses of opiates, often administered without concomitant anti-emetics. I should stress that I am not fingering any specific Trust in this scenario. It simply seems to be a fact of life in the NHS.
Additional problems which result in the cessation of epidural analgesia include a mixed bag of complications such as the appearance of blood around the catheter site (usually from the skin and not generally a sign of an epidural haematoma or migration of the catheter into a vein, although this latter can happen), leaking (usually a back-tracking of local anaesthetic from a partially displaced catheter and not cerebro-spinal fluid), and the most frustrating of all, the ‘it just fell out’ catheter.
I should stress that I am not minimising the catastrophic effects of a true complication of epidural placement, such as an abscess or haematoma formation. These are true disasters for the rare patient who experiences them and of course should always be borne in mind. The problem is that our vigilance for adverse effect of epidural analgesia, whether these be physiological or anatomical, combined with some straightforward design faults in the catheters themselves, are preventing us from giving a large number of patients a technique that should be a gold standard for intra-operative and post-operative pain relief.
What is the evidence in favour of perioperative epidural blockade for pain relief? The most quoted recent study1 looked at a large number of clinical trials in which the primary mode of post-operative analgesia was neuraxial blockade, either by spinal or epidural techniques, and compared these with patients that received general anaesthesia combined with analgesia by other means. As is often the case for this type of analysis, fine-tuning of the results was difficult because of power issues. Nevertheless, there is surprisingly strong evidence in favour of the use of neuraxial blockade in surgical patients. Overall mortality was reduced by one third in patients receiving neuraxial blockade, with or without general anaesthesia. Specific events such as deep vein thrombosis, pulmonary embolism, transfusion requirements pneumonia and respiratory depression were all dramatically reduced. In other words, the patient receiving neuraxial blockade for post-operative analgesia is less likely to die and less likely to experience complications that prolong his hospital stay than his counterpart languishing on PCA morphine.
More recent studies on mortality and length of hospital stay have confirmed these observations.2 These observations hold true for all types of surgery examined (with the possible exception of cardiac surgery, where epidural anaesthesia is still under review). Given the available evidence, it is this author’s opinion that it is not justifiable to deny a patient epidural analgesia for major surgery (including general and orthopaedic surgery), if the patient wishes it and the potential risks have been clearly explained to him.
So what is stopping us? Education, education, education for the ward-based medical and nursing staff is the first issue. Experience tells us that this must be repeated often and must be mandatory, if it is to succeed. It must also be hands-on, i.e. the staff must learn how the pumps work, what the physiology is, and given a protocol to follow that doesn’t just involve switching the pump off and hoping that a junior anaesthetist, who is often stuck in theatre, will turn up.
The second solution lies with the design of the epidurals themselves. In the last 20 years, the only real change in epidural technology has been the replacement of the glass loss-of-resistance syringes – which I was trained on - with plastic ones, which admittedly don’t fall on the floor and smash at 3.30am. Three things would make life easier:
- some kind of improved ‘sticky-backed’ plastic to hold the catheter in place. Tegaderm™ falls off sweaty patients.
- a much improved catheter-filter connection. This is an endless source of leaks, not to mention an infection risk.
- pumps that are easier to manipulate without going through several programmes and don’t bamboozle the ward staff. Some pumps are worse to set up than a DVD recorder. Under these circumstances, the on/off switch seems to be the easiest thing to find.
I propose the following deal: we train the staff, and industry builds a better device. That way we all win, especially the patient. How about it guys?
References
- Rodgers A et al. Reduction of post-operative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials. BMJ 2000; 321:1493-1503.
- Moraca RJ et al. The role of epidural anesthesia and analgesia in surgical practice. Ann Surg 2003;238:663-673.
Wireless Patient Monitoring
I. Overview
Over the past several years, consumers and businesses alike have enthusiastically embraced wireless communication. This widespread acceptance is due to the fact that wireless technologies greatly expand our freedom to communicate and exchange data, thus bringing unprecedented productivity and convenience to our business and personal lives.
Driven by the lower cost of wireless components, the healthcare sector is following a similar trend as the growth of wireless networking in hospitals is skyrocketing (See Figure 1 below). According to the market research firm Gartner Dataquest, “the healthcare provider market will witness a fundamental transformation in which wireless LANs will become an integral part of hospital networks, and mobile and wireless devices will become prevalent in the clinical setting.” Gartner predicts that, “by 2007, wireless networks will be an integral part of more than 65 percent of all healthcare provider network infrastructures.” As hospitals deploy mobile applications to improve operational efficiency, wireless networks will be installed initially for high patient throughput areas, including emergency rooms, critical care wards and nursing care floors.
Many compare the market acceptance of wireless local area networks (LANs) to the early days of the Ethernet. When Ethernet was adopted as a standard, it was quickly embraced as a way to network personal computers. Today, the adoption of wireless standards such as IEEE 802.11b/g (also known as Wireless Fidelity or “Wi-Fi”) and the use of mobile computing platforms form the basis of this wireless revolution. At the same time, clinical caregivers want to do more on a mobile basis and have grown accustomed to receiving information in real time via cell phones, pagers and PDAs. These factors have converged and are providing the impetus for a wide acceptance of wireless technologies within the healthcare industry.
According to published Garner Dataquest research, properly implemented wireless patient monitoring can help hospitals increase clinician productivity, improve patient outcomes and lower operational costs.
II. Why Hospitals are adopting wireless solutions
The healthcare sector has been familiar with wireless for many years, but its use has largely been confined to traditional telemetry-based patient monitoring, where the patient’s vital signs are only displayed at a central monitoring location. In the past few years, however, a proliferation of wireless carts has been deployed for clinical information system (CIS) charting and patient admitting applications. Hospital Information System companies which have traditionally offered various productivity applications for clinicians are now realizing that it makes sense to adapt their applications to operate on personal digital assistants (PDAs) or similar devices. This ease of use and mobility increase the adoption rate of these clinical applications.
The “laptop on a cart,” enabled by a wireless local area network (WLAN) card, has given clinicians the freedom to bring patient-specific information where they need it – which improves workflow, saving time and increasing productivity. Other workflow enhancing applications include the use of wireless PDAs for bar code scanning of prescriptions by nurses and innovative clinical software toolsets for physicians. Mobile applications improve workflow by bringing critical information to clinicians where they need it, across the continuum of care.
| Figure 1 |
Source: Gartner Dataquest (May 2004)
|
| U.S. Healthcare Provider Market, Wireless LAN Spending (Millions of Dollars) CAGR (%) |
|
2002 |
2003 |
2004 |
2005 |
2006 |
2007 |
2002-2007 |
| Healthcare Providers |
47.8 |
61.1 |
66.7 |
71.4 |
74.4 |
75.8 |
9.7 |
Healthcare is an ideal environment for the use of wireless and mobile computing technologies. From a process perspective, the hospital of today can be compared to a logistical or supply chain operation. There are multiple departments through which the patient moves; while at the same time, clinicians need information for real-time decision support. Clinicians must have access to the critical patient information at all times - wherever they are - without increasing their workload.
Goals of a wireless solution
Exactly what do healthcare providers hope to achieve by implementing a wireless solution? The goals include risk reduction when monitoring patients, better patient outcomes, increased staff efficiency and continuity of care (i.e., improved workflow), improved response time, and decreased costs in the care process - all while complying with HIPAA regulations. Here’s how wireless technology can answer each of these desired goals.
• Risk reduction when monitoring patients
Patient safety is always a top priority. To reduce risk, a hospital must automate repetitive tasks to eliminate human error, while allowing technology to work in the background to validate the outcome. Also, patient vital signs data should flow continuously to the clinical information system, whether the patient is on a wired or wireless network. The ability to monitor patients continuously allows for uncompromised vigilance and data collection. With wireless technologies, patient monitoring is not restricted to the traditional model whereby patient monitors are assigned to each room or bed. Rather, virtually any bed in the hospital can become a monitored bed. Real-time information is available wherever it is needed in the care process.
• Improved patient outcomes
When the hospital automates the process of collecting vital signs data and providing easy access to this information on a mobile basis, caregivers can make better decisions. Clinicians do not necessarily need more information. Rather, they need timely access to information so they can make evidence-based decisions on the spot, without having to search for information. Distributing clinical information - whether it is in the form of clinical alerts or the access of patient information on mobile devices in the wireless world - allows this to happen.
• Increased staff efficiency and continuity of care
Today’s patient care environment has become very information intensive. Multiple disparate devices collect information in real-time. However, patient care is foremost, and this often displaces the clinician’s ability to keep patient information current in all places. Many times this information is kept up in a retrospective fashion. Wireless technologies allow the continuous gathering of physiological information wherever the patient is in the care process, which allows caregivers to focus more on the care of the patient, rather than on the equipment.
• Improved response time
The response time to clinical events can be improved considerably when the appropriate wireless infrastructure is in place throughout each departmental area. In the case of an event, it would be ideal if information from a patient monitoring system and/or ventilator was distributed via wireless to the mobile caregiver. This would allow the clinician who may not be in front of a central station to be notified – regardless of location – and enable the appropriate response.
• Decreased costs in the care process
An automated flow of information into a clinical information system from real-time physiological and ventilation systems will alleviate the workload and costs associated with the charting of those parameters. Hospitals can improve the process and responsiveness to alarms when they automate and bring together the real-time information at the point of care, then distributing the relevant information to the mobile worker. This will allow clinicians to make better informed decisions, potentially speeding the patient through the delivery care process.
• Compliance with HIPAA requirements
In the wireless world, it is important that proper security measures are in place. Hospitals can comply with HIPAA regulations when they use standards-based wireless technologies, combined with the proper security and network monitoring strategies.
III. A monitoring vendor’s approach to integrated wireless monitoring
One of the first major providers in the patient monitoring field to offer standard WiFi wireless functionality across a wide range of its patient monitors is Dräger Medical. It is also the first monitoring vendor that can run patient monitors on the same network as other hospital applications. Through Dräger’s Infinity® wireless solutions, all vital patient data is transmitted to the Infinity Network for an uninterrupted flow of information to care team members at the bedside, the central station, or in remote locations. There are fewer information gaps to leave doctors and nurses uninformed and hinder lifesaving judgments. It offers wireless monitoring for all acuity levels and care areas.
To implement its wireless solutions, Dräger Medical formed strategic alliances with several industry leaders, including:
- Cisco Systems – the acknowledged industry leader in wireless and networking
- Packeteer® – the market leader in managing application traffic over wireless and wired networks and ensuring quality of service through dedicated bandwidth to monitoring information
- Anyware Network Solutions – an elite VAR of Cisco that delivers engineering and implementation services
- Siemens – world-class organization with proven experience in network infrastructure and wireless technology
The company subsequently expanded its commitment to wireless with the introduction of its Infinity Pocket WinView™remote viewing application, which enables caregivers to access wireless, near real-time patient data on their handheld computers. The Pocket WinView application can also share the same wireless infrastructure as the Infinity monitors and hospital applications.
IV. Potential advantages for the hospital
Standards-based architecture provides investment protection
Engineered with the future in mind, wireless monitoring is designed to meet the hospital’s rapidly changing information requirements and protect against obsolescence and the costly retraining of caregivers in the use of new products. Its standards-based, open architecture provides an upgrade path and integration with the hospital’s existing medical devices and HIS.
Uninterrupted monitoring ensures continuous surveillance
With the Infinity Wireless, the hospital can go from a docked monitoring environment to a wireless transport environment – without losing any data as the patient moves. As a result of the continuous wireless connection, clinicians in other care areas have remote access to vital patient data. This access can be from the in-house clinical information system, or even back out through the wireless network. Clinical information can be readily available and accessed through standard personal digital assistants (PDAs) enabled with wireless accessory cards. Available data can include individual patient vital signs, status information, patient trends, and waveform information.
In essence, information from stationary or telemetry patients can be automatically integrated with the wired CIS/HIS side, and then be distributed wirelessly throughout the enterprise. 
The result is uninterrupted patient monitoring, which enables continuous surveillance and enhances patient care.
V. Summary
The choice of wireless technology can lead to significant improvements in productivity and workflow, provide the potential for reduced errors, and decrease the costs of patient care. It will help healthcare institutions build a real-time care process, provide a continuous patient record across the continuum of care, and improve outcomes by creating an environment where clinicians can make evidence based decisions.
Chronic Refractory Angina - A Right Pain In The ChestAuthor: Dr Karen Stuart-Smith, Consultant Anaesthetist, Glan Clwyd Hospital, Denbighshire, Wales.
Chronic refractory angina is defined as debilitating angina poorly controlled by medication and considered unsuitable for coronary artery bypass surgery.1 Indeed, this author has seen such patients whose discomfort is relieved only by continuous infusion of glyceryl trinitrate via a central line. Until recently, these patients led a grim life of extremely limited mobility, constant pain, and the Damoclean sword of a life-threatening myocardial infarction.
In the last few years, a clearer understanding of the mechanism of anginal pain has allowed the development of novel techniques to relieve the discomfort of chronic myocardial ischaemia and even improve myocardial function. This article concentrates on one of the most effective and proven avenues: modulation of the cardiac nervous system.
The fundamental cause of angina is failure of the oxygen supply (due to atherosclerosis) to meet myocardial oxygen demand. The heart must keep pumping in the face of poor oxygen supply to maintain life, therefore there is a substantial switch to anaerobic metabolism with the consequent production of lactate and a localised metabolic acidosis. Substantial rises in extracellular potassium and inorganic phosphate inhibit excitation-contraction coupling and cross-bridge cycling very early in any exercise activity,2 leading to the sensation of fatigue and dyspnoea. The specific pain of angina seems to be result from sensitisation of myocardial visceral nerve endings by the by products of ischaemic metabolism, i.e. potassium, hydrogen ions and inflammatory prostaglandins. The next stage of the pathway is not clear, but ascending afferent activity from myocardial nerves reaches the limbic system, and is interpreted as a nociceptive stimulus.
It is speculated that a feedback loop is then established, which takes the form of a neurohormonal response to a perceived stress. The ultimate result for the myocardium is increased efferent sympathetic activity and overstimulation of alpha-adrenoceptors on coronary vessels. The result is further coronary arterial constriction, and persistence of the angina. There is some evidence to suggest that atherosclerotic coronary vessels have impaired release of endothelium-derived relaxing factors, and that this effect is specifically mediated via alpha-receptors, presumably on the endothelium itself.1 Patients with chronic refractory angina, or new-onset unstable angina exhibit profound cardiac sympathetic overactivity.3
Alpha-adrenergic vasoconstriction is extremely difficult to overcome pharmacologically in any vessel without the use of specific alpha-adrenceptors. Specific targeting of myocardial arteries is impossible, at least at present, so the use of any such agents is life-threatening.
On the other hand, we are talking about a group of patients for whom all pharmacological interventions have failed to control their pain and ischaemia. Since constant alpha-adrenergic activity is at the root of the problem, one potential solution is to specifically inhibit sympathetic activity. The simplest mechanism to achieve this is insertion of a thoracic epidural. In one such study,3 patients with chronic refractory angina were randomised to either maximal medical therapy or the insertion of a thoracic epidural at the T2-T5 level and continuous infusion of bupivacaine was commenced.
In brief, the results showed that those on conventional therapy continued to experience severe anginal pain, whereas those with epidural blockade had a considerably reduced number and severity of anginal episodes, such that their glyceryl trinitrate infusions could be stopped for the duration of the study.
On the face of it, this is not surprising, and could be attributed merely to the ‘numbing’ effect of the epidural. However the same authors have shown in previous studies that thoracic epidural anaesthesia blocked the excessive cardiac sympathetic activity associated with this condition, relieving the continuous constriction of the stenotic coronary arteries. This would suggest that epidural blockade breaks the ischaemia-pain loop in this form of angina, but further haemodynamic studies are required. The additional and obvious drawback is that continuous thoracic epidural analgesia is not really a long-term solution for all sorts of practical reasons. The authors suggest that it may be used as an emergency stop-gap in severely ill patients for whom revascularisation procedures may be a possibility.
An alternative method of alpha-adrenergic blockade in these patients is bilateral surgical thoracic sympathectomy via video-assisted thoracoscopic surgery.4 Patients undergoing this technique show reduced anginal symptoms and improved exercise tolerance, implying that there is improved myocardial perfusion, although accurate measures of myocardial performance are not yet available.
When researching this article the author found references to a high morbidity and mortality with this technique. However as these patients normally arrive in the anaesthetic room on maximal medical therapy including a glyceryl trinitrate infusion, it is the authors’ anaesthetic experience that these patients pose fewer risks than many elderly patients who present for much more minor procedures. There is no doubt, however, that a skilled surgeon who practices careful patient selection is vital to the success of this type of surgery.
The most practical techniques for interrupting the pain pathway in chronic refractory angina appear to be transcutaneous nerve stimulation (TENS) or direct spinal chord stimulation (SCS). The mechanism of action of these treatment modalities is fundamentally different from those described above, and are incompletely understood. Comprehensive and detailed reports on the use of TENS in severe angina are few and hard to find - it is a technique more often mentioned in passing in reviews rather than actively examined. Nevertheless, there is some evidence that TENS improves anginal symptoms and myocardial perfusion. The mechanism is completely unclear.
By contrast, a recent and careful study on the effects of spinal chord stimulation has been published.5 An electrode was placed into the epidural space at T4-5 and then moved up to C7-T1. The exact size of the stimulus is not recorded in the paper, but the signal was provided via an external stimulator, whose signal could be modulated by the patient - a sort of anginal PCA.
In brief, the patients experienced rapid improvement in symptoms and a dramatic reduction in nitrate consumption. Exercise tolerance also increased early in the treatment. The physiological effect on the heart was more difficult to interpret. Myocardial ischaemia (as measured by scintigraphy) improved much more slowly than did symptoms and exercise tolerance. The authors suggest that improved pain control allowed greater exercise tolerance, and so encouraged angiogenesis in the ischaemic heart. This may explain why symptoms continue to ameliorate even after cessation of neuro-modulatory therapy.
As the population ages and medical therapy in general continues to improve, it is very likely that the number of patients with chronic refractory ischaemia will continue to increase. A practical and long-lasting alternative to drugs or surgery is needed for these people. In researching this article, the author has been astonished by the sheer lack of research in this area, both in terms of understanding the basic pathophysiology and producing treatment strategies to deal with it. Urgent studies are needed. After all, speaking from personal experience, working in the NHS is likely to induce chronic refractory angina in all of us.
References
- DeJongste MJL et al. Chronic therapeutically refractory angina. Heart 2004;90:225-230.
- Jones NL and Killian KJ. Exercise limitation in health and disease.NEJM 2000;343:633-641.
- Olausson K et al. Anti-ischaemic and anti-anginal effects of thoracic epidural anaesthesia versus those of conventional medical therapy in the treatment of severe refractory unstable angina pectoris. Circulation 1997;96:2178-2182
- Khogali SS et al. Video-assisted thoracoscopic sympathectomy for severe intractable angina. Eur J Cardiothorac Surg 1999;16 Suppl 1:S95-98.
- Diedrichs H. Symptomatic relief precedes improvement of myocar dial blood flow in patients in patients under spinal cord stimulation. Curr Control Trials Cardiovasc Med 2005;6:7
Issue: June 2008
