Aneasthesia Pearls January 2015

ANAESTHESIA PEARLS

Compression Device

A Cricoid Cartilage Compression Device
Introduction:
Cricoid pressure is a means of preventing passive regurgitation and aspiration of gastric contents during rapid sequence induction of anaesthesia. It involves the application of backward pressure on the cricoid cartilage with a force of between 30 and 40 N in order to occlude the upper oesophagus (although latterly it has been suggested that a force of 20–30 N might be more appropriate). Failure to secure the airway in this way may put the patient at risk of developing aspiration pneumonitis, bacterial pneumonia and or bronchial blockage.
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The current recommendations with regard to technique are that cricoid pressure should be applied to the cricoid cartilage using the originally proposed three-finger technique (thumb, index and long finger opposed in the midline). Until quite recently, cricoid pressure was viewed as pinching the upper oesophagus between the cricoid ring and the 6th cervical vertebrae, however, it is now understood that the cricoid ring actually compresses the postcricoid hypopharynx, the oesophagus being typically 1 cm distal to the former. The latter confusion does not invalidate the technique; on the contrary, it does still compress the conduit between the stomach and the pharynx and, moreover, the technique is not compromised by lateral movement of the cricoid cartilage relative to the body of the vertebrae.
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There has been a raft of contra-indicatory findings that cricoid pressure may not even prevent regurgitation, and may actually induce nausea and vomiting, promote aspiration by relaxing the lower oesophageal sphincter, impede airway management, prolong intubation time by obscuring the laryngeal view ; and possibly lead to cricoid cartilage fracture and/or oesophageal rupture by the application of excessive force. Despite this negativity, there still seems to be a wide body of acknowledged medical and legal approval for using this technique in order to reduce patient risk.
Although ubiquitous, numerous studies have shown that knowledge and skills of cricoid pressure amongst anaesthetic and emergency department staff are still quite poor. The main deficiencies lie in the practitioners’ method of application and understanding of the correct amount of force to apply. However, to which anatomical structure the force should be applied also remains an issue.
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New Device:
With a view to circumventing this training need and so reduce patient risk, R. J. Taylor has developed a novel, plastic, recyclable, single-use, tactile feedback device that is cheap to manufacture (depending on quantity – a few pence), requires no power to operate or training to use and ensures the correct force is always consistently applied to the patient.
The device, which is suitable for manufacture by injection moulding (or 3D printing additive manufacturing), is made of polyoxymethene (Acetal™) and comes as a single piece of moulded plastic.
Figure 1 shows a schematic of the concept of operation of the tactile feedback instrument. The user grasps the central reinforced body of the device using the thumb, index and long finger opposed in the same configuration as he/she might use in the manual application of cricoid pressure. The lower concave section of the appliance is then placed over the cricoid cartilage and a downward force applied by the operator. At the point when 30 N of force is exerted (nominally 5 mm depression), the wedge on the left-hand side projects through and impinges the thumb or fingers (depending upon user orientation) above it (Fig. 2b). Further compression (typically another 1.8 mm depression) causes the pin on the right-hand side of the device to impact the proximal digit(s) (Fig. 2c). The latter occurs at a force of 35 N, informing the user that he/she is applying too much force. By careful regulation of the downward pressure applied, the operator may be confident that the force delivered to the cricoid cartilage never falls below 30 N nor exceeds 35 N. A set of push-fit foam pads (Fig. 3) are provided with the device to facilitate various applicator sizes covering a range of neck circumferences suitable for children, adolescents, average or large adults.
Fig 1 : Schematic illustrating the concept of operation :
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  Fig 2 : Operation of the device
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Fig 3 : Push-fit foam pads provide various sizes
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Authors Note : The details of this device were the subject of a patent application filed with the UK Intellectual Property Office in November 2012. It was our hope to attract the interest of a medical device manufacturer in the subsequent 12 months with a view to taking on a licence to manufacture the device on a commercial basis. Sadly, this did not happen and, due to the impending prospective financial burden of pursuing and maintaining the patent in this and other countries; we felt compelled to revoke the patent before its final ratification. We now find ourselves at a stasis with what we believe is a sound novel medical device, but unclear how its benefits can be passed on to others. In the spirit of true altruism, rather than waste this work, we prefer to share our knowledge and experiences of developing this device in the hope that someone may find the means to take it further.
Source :
A cricoid cartilage compression device for the accurate and reproducible application of cricoid pressure.
Anaesthesia, Volume 70, Issue 1, pages 18–25, January 2015.
Note : Author R. J. Taylor’s permission was obtained to display images.

Platelet Transfusion

A Clinical Practice Guideline of AAB
Platelet Transfusion: A Clinical Practice Guideline of AABB
(American Association of Blood Banks)
Platelet transfusions are administered to prevent or treat bleeding in patients with quantitative or qualitative platelet disorders. The AABB (formerly, the American Association of Blood Banks) developed this guideline on appropriate use of platelet transfusion in adult patients.
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Recommendation 1:
The AABB recommends that platelets should be transfused prophylactically to reduce the risk for spontaneous bleeding in hospitalized adult patients with therapy-induced hypoproliferative thrombocytopenia. The AABB recommends transfusing hospitalized adult patients with a platelet count of 10 × 109 cells/L or less to reduce the risk for spontaneous bleeding. The AABB recommends transfusing up to a single apheresis unit or equivalent. Greater doses are not more effective, and lower doses equal to one half of a standard apheresis unit are equally effective (Grade: strong recommendation; moderate-quality evidence).
Recommendation 2:
The AABB suggests prophylactic platelet transfusion for patients having elective central venous catheter placement with a platelet count less than 20 × 109 cells/L (Grade: weak recommendation; low-quality evidence).
Recommendation 3:
The AABB suggests prophylactic platelet transfusion for patients having elective diagnostic lumbar puncture with a platelet count less than 50 × 109 cells/L (Grade: weak recommendation; very low-quality evidence).
Recommendation 4:
The AABB suggests prophylactic platelet transfusion for patients having major elective non neuraxial surgery with a platelet count less than 50 × 109 cells/L (Grade: weak recommendation; very low-quality evidence).
Recommendation 5:
The AABB recommends against routine prophylactic platelet transfusion for patients who are nonthrombocytopenic and have cardiac surgery with cardiopulmonary bypass (CPB). The AABB suggests platelet transfusion for patients having CPB who exhibit perioperative bleeding with thrombocytopenia and/or evidence of platelet dysfunction (Grade: weak recommendation; very low-quality evidence).
Recommendation 6:
The AABB cannot recommend for or against platelet transfusion for patients receiving antiplatelet therapy who have intracranial hemorrhage (traumatic or spontaneous) (Grade: uncertain recommendation; very low-quality evidence).
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Source :
Platelet Transfusion: A Clinical Practice Guideline From the AABB.
Ann Intern Med. Published online 11 November 2014 doi:10.7326/M14-1589.

Postoperative Delirium


Postoperative Delirium Guideline
Postoperative Delirium Guideline for Older Adults
The American Geriatrics Society (AGS) has released a new practice guideline for preventing and treating postoperative delirium in patients aged 65 years or older.
Delirium is among the most common post-operative complications for older adults undergoing surgery. It is upsetting for patients and families, and can be harmful if not recognized and treated. Studies have shown that delirium can be prevented in up to 40% of cases in some hospitalized older adult populations. Surgical and related medical specialists, together with the multi-disciplinary members of their teams, can play an integral role in prevention.
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The recommendations in the best practices article range from what to do before, during, and after surgery to what not to do to prevent and treat delirium in postoperative patients.
They include :
Clinicians should perform a preoperative and postoperative assessment of delirium risk factors, including age older than 65 years, poor vision or hearing, severe illness, and presence of infection or chronic cognitive decline or dementia.
Healthcare professionals should be trained in the recognition and documentation of delirium signs and symptoms.
Anesthesiologists “may use processed electroencephalographic monitors of anesthetic depth during sedation or general anesthesia,” with the reasoning that administering fewer or lower doses will reduce postoperative delirium compared with deeper sedation.
Prescribers should avoid medications that may induce postoperative delirium, including anticholinergics, corticosteroids, meperidine, and hypnotics. The use of five or more medications increases the risk for delirium.
Clinicians should consider providing regional anesthesia during and after surgery for pain control.
Hospitals and healthcare systems should implement formal educational programs and refresher sessions and should develop multicomponent interventions to be delivered by multidisciplinary teams.
Prescribers should not prescribe antipsychotics or benzodiazepines to older patients who are not a threat for personal harm or harm to others and should not prescribe benzodiazepines as first-line treatment for such a patient.
Prescribers should use the lowest effective dose of benzodiazepines and antipsychotics for the shortest duration and only after behavioral interventions have failed.
I. Postoperative Delirium Risk Factors
Risk Factors for Postoperative Delirium
Age greater than 65 years
Cognitive impairment
Severe illness or comorbidity burden
Hearing or vision impairment
Current hip fracture
Presence of infection
Inadequately controlled pain
Depression
Alcohol use
Sleep deprivation or disturbance
Renal insufficiency
Anemia
Hypoxia or hypercarbia
Poor nutrition
Dehydration
Electrolyte abnormalities (hyper- or hyponatremia)
Poor functional status
Immobilization or limited mobility
Polypharmacy and use of psychotropic medications (benzodiazepines, anticholinergics, antihistamines, antipsychotics)
Risk of urinary retention or constipation
Presence of urinary catheter
Aortic procedures
II. Delirium Diagnosis
Symptoms Associated with Delirium
Change in level of arousal: drowsiness or decreased arousalor increased arousal with hypervigilance
Delayed awakening from anesthesia
Abrupt change in cognitive function (worsening confusion over hours or days), including problems with attention, difficulty concentrating, new memory problems, new disorientation
Difficulty tracking conversations and following instructions
Thinking and speech that is more disorganized, difficult to follow, slow, or rapid
Quick-changing emotions, easy irritability, tearfulness, uncharacteristic refusals to engage with postoperative care
Expression of new paranoid thoughts or delusions (ie, fixed false beliefs)
New perceptual disturbances (eg, illusions, hallucinations)
Motor changes such as slowed or decreased movements, purposeless fidgeting or restlessness, new difficulties in maintaining posture such as sitting or standing
Sleep/wake cycle changes such as sleeping during the day and/or awake and active at night
Decreased appetite
New incontinence of urine or stool
Fluctuating symptoms and/or level of arousal over the course of minutes to hours
III. Delirium Screening
Common Diagnostic Systems for Delirium
Diagnostic and Statistical Manual, 5th Edition, must meet all A – E Confusion Assessment Method Algorithm, must meet I, II, and either III or IV
A. Disturbance in attention (ie, reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment).
B. The disturbance develops over a short period of time (usually hours to a few days), represents an acute change from baseline attention and awareness, and tends to fluctuate in severity during the course of a day.
C. An additional disturbance in cognition (eg, memory deficit, disorientation, language, visuospatial ability, or perception).
D. The disturbances in criteria A and C are not better explained by a pre-existing, established, or evolving neurocognitive disorder and do not occur in the context of a severely reduced level of arousal such as coma.
E. There is evidence from the history, physical examination, or laboratory findings that the disturbance is a direct physiological consequence of another medical condition, substance intoxication or withdrawal (ie, due to a drug of abuse or to a medication), or exposure to a toxin, or is due to multiple etiologies.
I. Acute change and fluctuating course
a. Evidence of an acute change in mental status from the patient’s mental status prior to hospitalization, and
b. Evidence that abnormal behavior fluctuates during the day (ie, tends to come and go or increase and decrease in severity).
II. Inattention
Evidence of difficulty focusing attention, eg, being easily distractible, or having difficulty keeping track of what is being said.
III. Disorganized thinking
Evidence that thinking is disorganized or incoherent, such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject.
IV. Altered level of consciousness
Any evidence of any mental state other than a normal level of alertness. (Altered states include vigilant or hyperalert, lethargic, drowsy or easily aroused, stuporous or difficult to arouse, coma or unarousable.)
Validated Delirium Screening Instruments
General delirium screening instruments
Confusion Assessment Method (CAM) – short form
Delirium Symptom Interview (DSI)
Nursing Delirium Screening Scale (NuDESC)
Intensive care unit screening instruments
Confusion Assessment Method for the Intensive Care Unit (CAM-ICU)
Intensive Care Delirium Screening Checklist (ICDSC)
CAM is used by many as a screening tool (short form) and as a diagnostic instrument (long form plus the algorithm). Increased reliability is demonstrated when used by trained evaluators using cognitive screening tests rather than as a screening tool informed only by routine patient care.
IV. Intraoperative Measures to Prevent Delirium
The anesthesia practitioner may use processed electroencephalographic monitors of anesthetic depth during intravenous sedation or general anesthesia of older patients to reduce postoperative delirium.
V. Medications as Risk Factors for Postoperative Delirium
Posted in ANAESTHESIA PEARLS 2015

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