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Saudi Journal of Anaesthesia Vol. 6, Issue 4, October-December 2012
Letter to Editor
In the post-partum period as many as 30% of pregnant myasthenic patients may have exacerbated symptoms within 3 weeks of delivery.[3] The anticholinesterase requirements may vary and repeated evaluation of ventilation (including measurements of vital capacity), swallowing and speech is recommended. Regional anesthesia also has the advantage that it ensures minimal interference with gut function thus allowing early resumption of oral anticholinesterase therapy.
Though general anesthesia has been used conventionally, neuraxial anesthesia can be safely used if patient selection is proper, and high level of sensory–motor block is prevented.
Surbhi D. Mundada, Bharat Shah, Sukriti AtramDepartment of Anaesthesia and Critical Care,
Sir J.J. Group of Hospitals, Mumbai, India
Address for correspondence: Dr. Surbhi D. Mundada,
Department of Anaesthesia and Critical Care, Grant Medical College and Sir J.J. Group of Hospitals,
Byculla, Mumbai-8, Maharashtra, India. E-mail: [email protected]
RefeRences
1. Plauche WC. Myasthenia gravis. Clin obstet Gynecol 1983;26:592‑604.
2. djelmis J, Sostarko M, Mayer d, ivanisevic M. Myasthenia gravis in pregnancy: report on 69 cases. Eur J obstet Gynecol reprod Biol 2002;104:21‑5.
3. Coaldrake la, livinstone P. Myasthenia gravis in pregnancy. anaesth intensive Care 1983;11:254‑7.
4. datta S. autoimmune disease. in: anaesthetic and obstetric management of high‑risk pregnancy. 2nd ed. Philadelphia, Pa: Mosby: 1996. p. 357‑61.
5. rolbin WH, levinson G, Shnider SM, Wright rG. anaesthetic considerations for myasthenia gravis and pregnancy. anesth analg 1978;57:441‑7.
6. Usubiaga JE, Wikinski Ja, Mori rl, Usubiaga lE. interaction of intravenously administered procaine, lidocaine and succinylcholine in anaesthetized subjects. anesth analg 1967;46:39‑45.
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Troubleshooting management for bleedback after arterial cannulation used for invasive hemodynamic monitoring
Sir,
Arterial cannulations are commonly done for invasive continuous hemodynamic monitoring in patients in critical care settings and undergoing major surgeries with anticipated perioperative hemodynamic instability owing tomajor fluid shifts, significant blood loss, autonomicdisturbances, and cardiovascular diseases. It also provides a site for arterial blood sampling and cardiac output determination. Yet, arterial cannulations are not without problems and complications. Most common problems encountered are bleedback and air bubble in pressure monitoring line, dampened waveforms, thrombosis, hematoma, bleeding, and infections.[1] Here, we report the problem of bleedback in pressure monitoring line while doing invasive hemodynamic monitoring, due to the use of nonstandardized, low-cost pressure monitoring tubing and its troubleshooting management.
A 45-year-old male patient (ASA grade 3) with hypertensive intracranial bleed (posterior communicating artery aneurysm) was posted for urgent surgical clipping in emergency operating room (OR). After institution of general anesthesia the patient was planned for arterial and central venous pressure (CVP) cannulations for continuous hemodynamic monitoring. Due to nonaffordability of patient a 20 G intravenous(IV) cannula (Vein Cath™ GS-3024, Romsons®, India) was inserted in the left radial artery under all aseptic precautionsafterperformingpositivemodifiedAllen’stest.[2] Low-cost pressure monitoring tubing (Shanghai Kohope Medical Devices™, China) was attached to the cannula and then connected to the arterial pressure monitoring transducer (BD DTXPlus™, USA) for continuous arterial blood pressure monitoring. After 15 min of the placement, dampening of the pressure waveform with bleedback from arterial cannula into pressure tubing was observed, reaching
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Page | 432
Vol. 6, Issue 4, October-December 2012 Saudi Journal of Anaesthesia
Letter to Editor
Figure 3: Stopcock attachment at pressure transducer
Figure 1: Bleedback in pressure monitoring tubing and pressure transducer
Figure 2: Stopcock attachment at arterial cannula
all the way up to the transducer [Figure 1]. The arterial cannulaandpressuretubingweredynamicallyflushedwithheparinized saline but the problem persisted. To counteract the problem we immediately placed two three-way stopcocks (Smiths Medical Medex® MX5311L, UK) on both ends of the pressure monitoring (PM) tubing, one between the PM tubing and arterial cannula [Figure 2] and the other at the junction of transducer and the PM tubing [Figure 3]. Zeroing (setting atmospheric pressure as zero reference point) was done and pressure monitoring system was reactivated. No bleedback was observed thereafter and successful arterial pressures were recorded throughout the surgery and in the postoperative period.
The problem of bleedback with arterial cannulations is described in the literature due to loose connections, a partially deflated pressure bag, or incorrect stopcockposition.[1] The blood flow through vessel column or hemodynamic line is governed by various physical factors asdescribedbyHagen–Poiseuillelaw(flow=�(Pi–Po)r4/8ηl,wherePi –Po=hydrostatic pressure gradient,r =radius of the tubing, η= coefficient of viscosity,l = length of tubing).[3] Thus blood flow will vary in proportion to pressure gradient and diameter of blood column.Thetotalfluidenergy,whichisthesummationof pressure energy (potential energy), gravitational potential energy (ignored when liquid moves horizontally), and kinetic energy, determines the liquid movement between two points inatube.Keepingthetotalfluidenergyconstant,thelateralhydrostatic pressure (P) is altered due to the changes in the velocityof flow,whichinturnchangesthekineticenergy.If tubecontainingfluidnarrowsindimension,thevelocityof flow,andtherebythekineticenergyincreases.Thisresultsin decreased potential energy, such that the measured lateral hydrostatic pressure (P) decreases in narrowed section. If tubewidenssuddenly,thevelocityof flowandkineticenergy fall, so P measured increases.[4] These principles of physics explain why variation in diameter of hemodynamic lines(pressuretubing)mightcausebackwardflowof blood(bleedback) into pressure tubing causing dampening of arterial waveform and faulty blood pressure readings.
According to other studies, radial artery internal diameter is 2.34±0.37 mm.[4,5] The 20 G IV cannula used for arterial cannulations has an ID (internal diameter) of 1.1 mm and length of 32 mm, compared with the standard recommended angiocath of 20 G, having ID 1.1 mm and length of 45–60 mm (BD Floswitch™, USA, BD Careflow™, USA). Standard high-pressure tubings used have an internal diameter of 2.5–2.7 mm (B Braun®, Germany, BD®, USA). We observed that the nonstandardized, low-cost pressure tubings generally have an ID of more than 5.0 mm. Sudden and gross difference in ID of arterial cannula and pressure tubing, thus results in
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Saudi Journal of Anaesthesia Vol. 6, Issue 4, October-December 2012
Letter to Editor
RefeRences
1. arterial catheter complications and management problems: observations from aaCN’s thunder Project. Care Nurs Clin North am 1993;5:557‑62.
2. Puttarajappa C, rajan dS. images in clinical medicine. allen’s test. N Engl J Med 2010;363:e20.
3. Power i, Kam P. Cardiovascular Physiology: Physical factors governing blood flow through vessels. In: Power I, Kam P, editors. Principles of Physiology for the anaesthetist. 2nd ed. oxford: Hodder arnold Publications; 2008. p. 140‑5.
4. Brzezinski M, luisetti t, london MJ. radial artery cannulation: a comprehensive review of recent anatomic and physiologic investigations. anesth analg 2009;109: 1763‑81.
5. Ku YM, Kim Yo, Kim Ji, Choi YJ, Yoon Sa, Kim YS, et al. Ultrasonographic measurement of intima‑media thickness of radial artery in pre‑dialysis uraemic patients: Comparison with histological examination. Nephrol dial transplant 2006;21:715‑20.
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problem of bleedback and faulty pressure readings. We have observed that if a three-way stopcock is placed between arterial cannula and pressure tubings, which have an ID of 3 mm, then there is no bleedback from the cannula. The smaller ID of three-way stopcock offers additional resistancesuchthat,thehemodynamiclinefluidpressureis enough to counter balance the arterial pressure, and thereby prevents bleedback.
We conclude that in the third world countries, many a times high cost of recommended products restrains their use in poor population, although they remain the standard of care. As such, use of low-cost pressure tubings may be done for arterial pressure monitoring in these circumstances and the common problem of bleedback encountered could be easily prevented by practicing the use of the three-way stopcock on both ends of the pressure monitoring line.
Dheeraj Kapoor, Meghana SrivastavaDepartment of Anaesthesia and Intensive Care, Govt. Medical
College and Hospital, Chandigarh, India
Address for correspondence: Dr. Dheeraj Kapoor,
Department of Anaesthesia and Intensive Care, Govt. Medical College and Hospital, 1207, Sector 32 B, Chandigarh - 160 030, India.
E-mail: [email protected]
A simple modification of pediatric and adult Macintosh laryngoscopes for oxygen insufflation
Sir,
We propose a simple method for pharyngeal oxygen insufflation during paediatric and adult Macintosh laryngoscopy [Figure 1]. A 06 FG size suction catheter isfixedtothelaryngoscopebladeintheanglebetweenthe tongue and the web using paper tape, [Figure 2] with the side hole near the tip exposed, and the tip midway between tip of the bulb and the tip of the laryngoscope blade [Figure 3]. The proximal end of the catheter is connected to the tubing of an oxygen source (e.g., auxiliary oxygen flowmeter of the anaesthesiamachine),andaflowof 2‑6L/minute[1] oxygen can be used. The catheter can also be connected to a suction source for a short while to suction out oropharyngeal secretions if the need arises. This can be used for all sizes of Macintosh blades, from 0 to 5. Figure 1: Modified Macintosh blade
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