In patients in whom the risk of reinfection is high purchase online lansoprazole, such as in drug addict patients [28] order lansoprazole 15mg fast delivery, the aortic valve replacement with aortic allograft yields better results than prosthesis [29] discount lansoprazole 15 mg with amex. Some studies have shown that the rate of reinfection is lower in patients who have undergone an aortic valve replacement with an allograft buy lansoprazole 30 mg with amex, suggest- ing that allograft is more resistant to infection than prosthesis [30 – 32]. Indeed, the risk for reinfection after an aortic valve replacement with prosthesis is higher in the first months following the surgical procedure (initial phenomenon), whereas the risk is low when allograft is utilised [30 – 32]. Although the reasons are not elucidated, the whole biological surface, the viability of allograft tissue, and low gradient obtained after aortic valve replacement by allograft, avoiding turbulence, seem to be the main reasons for the greater resistance to infection. In contrast, longevity (par- ticularly in young patients), availability (mostly when surgical procedures are car- ried out in an emergency setting), and technical problems during a re-operation must temper the use of allograft. Prosthetic Aortic Valve Endocarditis When infectious involvement is limited to the aortic prosthesis with no major lesion concerning the aortic ring, the annular debridement and reconstruction should be done as described previously, followed of an aortic valve replacement. Replacement done with tissue or mechanical prosthesis yields the same immediate and long-term results [16, 25, 26 , 29]. Collart Native or Prosthetic Aortic Valve Endocarditis with Extended Lesions of the Aortic Ring An early surgical treatment is more frequently mandatory in patients with an aortic abscess than in isolated aortic valve involvement (87 versus 50%) [33]. In circular destruction of the aortic ring as well as in lesions near to the coronaries ostia, in which repair can compromise the coronary circulation, is difficult to restore a strong structure in order to anchor a valve prosthesis. The flexibility of allograft tissue allows the achievement of suture without tension, which is important in the manipulation of weakened tissues. The allograft tissue (anterior mitral leaflet, aortic wall) can be used to reconstruct or reinforce left ventricular outflow. Moreover, allograft is more resistant to infection, as the majority of homograft series report a recurrent endocarditis rate less than 8% [30–32]. The longevity of allograft is the same as that of bioprosthesis in aortic position. The rate of reintervention’s mortality after allograft valve or root replacement has been reported to be similar to that of bioprosthesis by some authors [34 , 35]. In con- trast, a significantly increased mortality has been observed in others studies [36]. Moreover, large sizes are avail- able, which is an advantage mostly for aortic rings larger than 25. In contrast, their resistance to infections is similar to bioprosthesis, and reinterventions can be as difficult [37, 38 ]. The Ross procedure may be useful in young patients where the degeneration and calcification of aortic allograft will expose the patients to a reoperative aortic root procedure [11]. In cases with limited annular involvement, reconstruction of the aortic ring and aortic valve replacement are safe treatments and get good immediate and long-term results. The utilisation of allograft and stentless bioprosthesis has been reported to offer advantages when compared with stented prosthesis [11 ]. Mitral Valve Endocarditis The mitral valve is affected in 45% of infective endocarditis, but only in 35% is surgical treatment necessary [33]. If the disease is limited to the valvular tissue, mitral valve repair is the preferred surgical option [42–44]. The rate for freedom from re- intervention at 5 and 10 years was 89 % and 72 % respectively [46]. Anterior Mitral Leaflet Isolated lesions of the body of the anterior mitral leaflet are prone to be repaired. Indeed, if lesions respect the free border of the leaflet, debridement and resection of the margin of the lesion followed by suture of a tanned autologous or bovine peri- cardial patch meet with good results. This type of lesion may be associated with an aortic regurgitation (kissing lesion) (Figs. When there is no aortic dysfunction associated or when other involvements of the mitral valve--such lesion of chordae, posterior leaflet or mitral ring—exist, the atriotomy is the standard approach. Collart When the free margin of the anterior leaflet is involved with chordae rupture, repair is more challenging. Repair is difficult when chordae rupture is associated with a huge destruction of the free edge of the anterior leaflet, especially on A2; under these conditions, mitral valve replacement should be considered. Commissural Lesions In commissural lesions of the mitral valve, debridement and resection of infected tissues followed by reconstruction by sliding plasty, or annular plicature are fre- quently feasible. Sliding plasty is preferred in the anterior commisure, since annular plication may produce an obstruction of the circumflex artery. In circum- scribed lesions without involvement of the free margin of the valve, repair with a patch of tanned pericardium is a safe solution. When the free margin and chordae are involved, a classical quadrangular resection with sliding plasty or annular plica- tion can be done (Fig. In cases of extensive destruction of the posterior mitral leaflet with huge loss of substance, reconstruction is more difficult, and large peri- cardial patch and neochordae are necessary. Even if immediate results are satisfac- tory, mid-term results are suboptimal; therefore, mitral valve replacement must be considered. A prosthetic annuloplasty ring may be necessary to achieve satisfactory repair during complex reconstruction [43, 47] and is well tolerated, with a low reinfection rate [43]. As an alternative, some authors have proposed using a strip of bovine or autologous glutaraldehyde- treated pericardium [46 ]. Abscesses in the intertrigonal space are almost always associated with the involvement of the aortic valve; see previous discussion in this chapter. Mitral valve reconstruction: resection of infective lesion (P2) and sliding plasty Fig. The repair of an annular abscess is done by debridement of the lesion and reconstruction by suturing the atria to the ventricular wall. Both mechanical and bioprosthetic valves have been used in mitral valve replacement [16, 25, 41]. Although a few authors use mechanical valves almost exclusively [26 , 48], the majority use both bioprosthetic and mechanical valves, with similar sur- vival rates and freedom from reinfection [16, 25]. The risk of reoperation, however, appears to be higher among patients with tissue valve replacement [16, 24, 25]. Overall, valve choice should be individualized according to age, life expectancy, and presence of comorbidities. Surgical treatment is mandatory in patients with right cardiac failure in spite of diuretics treatment, in patients under antimicrobial treatment with persistent large vegetations (>20 mm. The surgical removal of the tricuspid valve [51] (Arbalu procedure) without replacement has been advocated but may be associated with severe post-operative right heart failure, particularly in patients with elevated pulmonary arterial pressure, which is often the case after multiple pulmonary emboli. It may be performed in extreme cases, but the valve should be subsequently replaced once the infection has been cured [51]. Mitral allograft has been reported as a useful alternative for tricus- pid valve replacement with encouraging results [52]. When pulmonary valve replacement is necessary, the use of pulmonary allograft is the best choice [31 ]. The approach in case of multiple valve involvement is the same as described previously. The patient’s background must be considered when considering tissue or mechanical prosthesis [11]. When the mitro-aortic curtain is involved, reconstruction followed by mitro-aortic valve replacement is a difficult procedure resulting in to high morbidity and mortality [36, 54]. As an alternative to this challenging situation, reconstruction and replacement with an “in bloc mitro- aortic allograft” has been reported with promising results; however, this approach must be reserved for extreme patients [55 ]. Conclusion The progress made in clinical diagnosis, imaging, antimicrobial treatment, and post- operative care has enabled the surgical treatment of patients who are more seriously ill. Conservative surgical treatment should take place when possible, especially for the atrioventricular valves. When a prosthetic valve replacement is necessary, the type of prosthesis (tissue or mechanical) has no influence on results and must be adapted depending on a patient’s background. Risk of embolism and death in infective endocarditis: prognostic value of echocardiography: a prospective multicenter study. Clinical and prognostic profile of patients with infective endocarditis who need urgent surgery.

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Autoregulation of urine flow does not occur order lansoprazole cheap, but a linear relationship between mean arterial pressure above 50 mmHg and urine output is observed order cheap lansoprazole. During periods of reduced renal perfusion buy lansoprazole online from canada, the metabolically active medullary thick ascending limb may be especially vulnerable to ischemic injury buy cheap lansoprazole. Renal cortical vasoconstriction causes a shift in perfusion toward juxtamedullary nephrons, a decrease in glomerular filtration rate, and retention of salt and water result. Likewise, anesthetic agents have not been shown to interfere with the renal response to physiologic stress. The single most reliable predictor of new postoperative need for dialysis is preoperative renal insufficiency. Knowledge of specific concerns relevant to the different irrigating solutions, vigilance of the anesthesiologist to factors that minimize absorption, recognition of signs and symptoms, and appropriate treatment, are key to favorable outcomes with this condition. Introduction and Context The kidney plays a central role in implementing and controlling a variety of homeostatic functions; these include tight control of extracellular fluid volume and composition and efficient excretion of uremic toxins in the urine. The second part describes current urologic procedures and their attendant anesthetic management issues. Renal Anatomy and Physiology Gross Anatomy The two normal kidneys are reddish-brown organs and are ovoid in outline, but the medial margin is deeply indented and concave at its middle, where a wide, vertical cleft (the hilus) transmits items entering and leaving the kidney (Fig. The kidneys lie in the paravertebral gutters, behind the peritoneum, with the right kidney resting slightly lower than the left one owing to the presence of the liver. At its upper end, the ureter is dilated to give rise to the renal pelvis, which passes through the hilus into the kidney proper. There it is continuous with several short funnel-like tubes (calyces) that unite it with the renal parenchyma. The renal blood vessels lie anterior to the pelvis of the kidney, but some branches may pass posteriorly. Renal pain sensation is conveyed back to spinal cord segments T10 through L1 by sympathetic fibers. The vagus nerve provides parasympathetic innervation to the kidney, and the S2 to S4 spinal segments supply the ureters. Each kidney is enclosed in a thick, fibrous capsule, itself surrounded by a fatty capsule that fills the space inside a loosely applied renal (Gerota) fascia. The developing kidney is first formed in the pelvis and then ascends to its final position on the posterior abdominal wall. During its ascent, the kidney receives blood supply from several successive sources, such that an accessory renal artery from the aorta may be found entering the lower pole of the kidney. When first formed, the rudimentary kidneys are close together and may fuse to give rise to a horseshoe kidney. This organ is unable to ascend, “held in place” by the inferior mesenteric artery, and thus when present it remains forever a pelvic organ. The bladder is located in the retropubic space and receives its innervation from sympathetic nerves originating from T11 to L2, which conduct pain, touch, and temperature sensations, whereas bladder stretch sensation is transmitted via parasympathetic fibers from segments S2 to S4. The prostate, penile urethra, and penis also receive sympathetic and parasympathetic fibers from the T11 to L2 and S2 to S4 segments, respectively. The pudendal nerve provides pain sensation to the penis via the dorsal nerve of the penis. Sensory innervation of the scrotum is via cutaneous 3508 nerves, which project to lumbosacral segments, whereas testicular sensation is conducted to lower thoracic and upper lumbar segments. Ultrastructure Inspection of the cut surface of the kidney reveals the paler cortex, adjacent to the capsule, and the darker, conical pyramids of the renal medulla (Fig. The pyramids are radially striated and are covered with cortex, extending into the kidney as the renal columns. Collecting tubules from each lobe of the kidney (pyramid and its covering of cortex) discharge urine into the calyceal system via renal papillae at the entrance of each pyramid into the calyx proper. These collecting tubules originate deep within the radial striations (medullary rays) of the kidney and convey urine formed in the structural units of the kidneys, the nephrons. The parenchyma of each kidney contains approximately 1 × 10 tightly packed nephrons, each one consisting of a tuft6 of capillaries (the glomerulus) invaginated into the blind, expanded end (glomerular corpuscle) of a long tubule that leaves the renal corpuscle to form the proximal convoluted tubule in the cortex. This leads into the straight tubule, which loops down into the medullary pyramid (loop of Henle) and hence back to the cortex to become continuous with the distal convoluted tubule. This then opens into a collecting duct that is common to a number of nephrons and passes through the pyramid to enter the lesser calyx at the papilla. It is in these parts of the nephron (proximal tubule, loop of Henle, distal tubule, and collecting duct) that urine is formed, concentrated, and conveyed to the ureters. The distal convoluted tubule comes into very close contact with the afferent glomerular arteriole, and the modified cells of each form the juxtaglomerular apparatus, a complex physiologic feedback control mechanism contributing in part to the precise control of intra- and extrarenal hemodynamics that is a hallmark feature of the normally functioning kidney. As is the case for the renal tubules, the vasculature of the kidney is highly organized. The renal artery enters the kidney at the hilum and then divides many times before producing the arcuate arteries that run along the boundary between cortex and outer medulla. Interlobular arteries branch from arcuate arteries toward the outer kidney surface, giving rise as they pass through the cortex to numerous afferent arterioles, each leading to a single glomerular capillary tuft. The barrier where filtration from the vascular to tubular space within the glomerulus occurs is highly specialized and includes fenestrated negatively charged capillary endothelial cells and tubular epithelial cells (podocytes) separated by a basement membrane. Normally, selective permeability permits approximately 25% of the plasma elements to pass into the Bowman capsule; only cells and proteins more than 60 to 70 kDa cannot cross. However, abnormalities of this barrier can occur with disease, which 3509 may permit filtration of much larger proteins and even red blood cells; these changes manifest as the nephrotic syndrome (proteinuria >3. The glomerular capillaries exit Bowman capsule and merge to form the efferent arteriole and peritubular capillaries that nourish the tubules. The renal vasculature is unusual in having this arrangement of two capillary beds joined in series by arterioles. Blood supply to the entire tubular system comes from the glomerular efferent arteriole, which branches into an extensive capillary network. Some of these peritubular capillaries, the vasa recta, descend deep into the medulla to parallel the loops of Henle. The vasa recta then return in a cortical direction with the loops, join other peritubular capillaries, and empty into the cortical veins. Figure 50-1 A: The gross anatomy and internal structure of the genitourinary system and kidney. B: Internal organization of the kidney includes cortex and medulla regions and the vasculature. D: Plasma filtration occurs in the glomerulus; 20% of plasma that enters the glomerulus passes through the specialized capillary wall into the Bowman capsule and enters the tubule to 3510 be processed and generate urine. The functions of the kidney are many and varied, including waste filtration, endocrine and exocrine activities, immune and metabolic functions, and maintenance of physiologic homeostasis. As well as tight regulation of extracellular solutes such as sodium, potassium, hydrogen, bicarbonate, and glucose, the kidney also generates ammonia and glucose and eliminates nitrogenous and other metabolic wastes including urea, creatinine, bilirubin, and other uremic toxins (i. Finally, circulating hormones secreted by the kidney influence red blood cell generation, calcium homeostasis, and systemic blood pressure. The kidney fulfills its dual roles of toxin excretion and body fluid management by filtering large amounts of fluid and solutes from the blood and secreting waste products into the tubular fluid. Effects on the normal filtration and reabsorption processes of comorbid disease, surgery, and anesthesia are the focus of the next section. Glomerular Filtration Production of urine begins with water and solute filtration from plasma flowing into the glomerulus via the afferent arteriole. The ultrafiltration constant (Kf) is directly related to glomerular capillary permeability and glomerular surface area. Recent general revisions of Starling’s original 3511 formula to incorporate the newly appreciated importance of the endothelial glycocalyx layer also appear to be relevant to glomerular filtration, particularly for pathologic states that involve proteinuria (e. Renal autoregulation of blood flow and filtration is accomplished primarily by local feedback signals that modulate glomerular arteriolar tone to protect the glomeruli from excessive perfusion pressure (Fig. Several mechanisms for regulating blood flow to the glomerulus have been described, and all involve modulation of afferent glomerular arteriolar tone. The myogenic reflex theory holds that an increase in arterial pressure causes the afferent arteriolar wall to stretch and then constrict (by reflex); likewise, a decrease in arterial pressure causes reflex afferent arteriolar dilatation. Chloride also acts as the feedback signal for control of efferent arteriolar tone. In response to angiotensin, efferent arteriolar constriction increases glomerular pressure, which increases glomerular filtration. It is important to realize that autoregulation of urine flow does not occur, and that above a mean arterial pressure of 50 mmHg there is a linear relationship between mean arterial pressure and urine output.

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There is a common set of layers covering and forming the abdom- inal wall: the deepest are the extraperitoneal fat and peritoneum buy generic lansoprazole. The abdominal muscles 3 Anatomy and Physiology of the Abdominal Compartment 37 Table 3 buy lansoprazole. Abdominal Distention This is defned as a sagittal abdominal diameter (approxi- mately at the level of the umbilicus) higher than the virtual line between xiphoid and symphysis pubis buy lansoprazole with paypal. An increased compliance indicates a loss of elastic recoil of the abdominal wall (e buy lansoprazole with a visa. As stated, true Cab can only be measured in case of addition or removal of a known abdominal volume (e. Related to increased intra-abdominal contents – Gastroparesis – Gastric distention – Ileus – Volvulus – Colonic pseudo-obstruction – Abdominal tumor – Retroperitoneal/ abdominal wall hematoma – Enteral feeding – Intra-abdominal or retroperitoneal tumor – Damage control laparotomy B. Related to abdominal collections of fuid, air, or blood – Liver dysfunction with ascites – Abdominal infection (pancreatitis, peritonitis, abscess, etc. In a study by Vidal and colleagues, 53% of trauma and emergency surgery 3 Anatomy and Physiology of the Abdominal Compartment 43 Table 3. Related to anthropomorphy and with decreased abdominal demographics compliance (adapted from • Male gender Malbrain et al. As stated before, the use of direct intraperitoneal pressure measurement cannot be advocated in patients because of the complication risks (bleeding, infection) and should only be used in an experi- mental setting or when combined with fuid drainage (paracentesis). Over the years, bladder pressure measurements have been forwarded as the gold standard technique. The interactions between different body compartments have been referred to as the polycompartment model and syn- drome [7, 34]. The interactions between compartments are not only dependent on the specifc elas- tance of the different components but also on baseline pressures within the different compartments. Results from the international conference of experts on intra-abdominal hypertension and abdominal compartment syndrome. Results from the international conference of experts on intra-abdominal hypertension and abdominal compartment syndrome. Intra-abdominal hypertension and the abdominal compartment syndrome: updated consen- sus defnitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome. Incidence and prognosis of intraabdominal hypertension in a mixed population of critically ill patients: a multiple-center epidemiological study. Prevalence of intra-abdominal hypertension in critically ill patients: a multicentre epidemiological study. A systematic review and individual patient data meta-analysis on intra-abdominal hypertension in critically ill patients: the wake-up project. Historical highlights in concept and treatment of abdominal compartment syn- drome. A Society dedicated to the study of the physi- ology and pathophysiology of the abdominal compartment and its interactions with all organ systems. The role of abdominal compliance, the neglected parameter in critically ill patients - a consensus review of 16. The role of abdominal compliance, the neglected parameter in critically ill patients - a consensus review of 16. Mechanical properties of the human abdominal wall measured in vivo during insuffation for laparoscopic surgery. Forces and deformations of the abdominal wall--a mechanical and geometrical approach to the linea alba. Mechanically relevant consequences of the composite laminate-like design of the abdominal wall muscles and connective tissues. Intra-abdominal pressure mea- surement using a modifed nasogastric tube: description and validation of a new technique. Impact of the patient’s body position on the intraabdominal workspace during laparoscopic surgery. Risk factors for intra-abdominal hypertension and abdominal compartment syndrome among adult intensive care unit patients: a systematic review and meta-analysis. Intra-abdominal hypertension and abdominal compartment syndrome in pancreatitis, paediat- rics, and trauma. Intra- abdominal hypertension and abdominal compartment syndrome in burns, obesity, pregnancy, and general medicine. Incidence and clinical effects of intra-abdominal hypertension in critically ill patients. Both pri- mary and secondary abdominal compartment syndrome can be predicted early and are harbin- gers of multiple organ failure. An overview on fuid resuscitation and resuscita- tion endpoints in burns: past, present and future. Part 2 - avoiding complications by using the right endpoints with a new personalized protocolized approach. An overview on fuid resuscitation and resuscitation endpoints in burns: past, present and future. Intra- abdominal pressure measurement using the FoleyManometer does not increase the risk for urinary tract infection in critically ill patients. Intra- and interobserver variability during in vitro vali- dation of two novel methods for intra-abdominal pressure monitoring. The polycompartment syndrome: towards an understanding of the interactions between different compartments! The infuence of intraabdominal hypertension on the cen- tral nervous system: current insights and clinical recommendations, is it all in the head? Renal implications of increased intra- abdominal pressure: are the kidneys the canary for abdominal hypertension? The Open Abdomen: Balancing 4 Pathophysiologic Benefits and Risks in the Era of Improved Resuscitation Practices Derek J. Appropriate anatomical indications identifed in these studies included several abdominal injury patterns and an inability to close the abdominal fascia because of visceral edema [2–5]. Finally, appropriate logis- tical reasons involved a planned relaparotomy to remove packs, reassess bowel viability (e. Open abdominal management has long been reported to be associated with a number of physiological benefts among critically ill trauma, general, and vascular surgery patients. Abbreviated surgery theoretically helps prevent further bloodshed and avoids the onset of (and/or interrupts) the “vicious cycle” of hypothermia, acidosis, and coagu- lopathy [3, 8, 9]. However, open abdominal management has also been associated with a high rate of energy loss and a substantial incidence of potentially severe complications (intra- abdominal sepsis, enteric leaks, enteroatmospheric fstula formation, and massive ventral hernias) [3, 15–17]. The management of these complications often requires a number of hospital readmissions and subsequent surgical procedures [3, 15–17]. Thus, decisions regarding whether open abdominal management is indicated or not should be based on modern evidence or until such evidence becomes available and the opinions of experts and the currently practicing surgical community [2–5]. We end with a description of the present knowledge regarding the pathophysiology of progressive loss of abdominal domain, massive ventral hernias, enteric leaks, enteroatmospheric fstulae formation, and accelerated energy expen- diture in this patient population. Thus, principles that were once deemed dogma, such as the importance of judging whether a seriously injured patient would 58 D. However, it is becoming increasingly apparent that injury and infection are signifcantly different pathophysiologic insults [25]. Those with infection may be disproportionately affected by persistent infam- mation and its associated obligatory edema [25]. Exsanguination, or a blood loss exceeding 40% of total body blood volume with ongoing bleeding, is often associated with development of a lethal triad (or “vicious cycle”) of hypo- thermia (core body temperature < 34 °C), acidemia (pH < 7. Importantly, all three components of the lethal triad may be precipitated or exacerbated by the administration of large volumes of crystalloid fuids. Historically, hypothermia occurred in 57–66% of severely injured patients treated with standard, crystalloid-based resuscitation practices [29, 30]. This com- plication typically occurred after profound shock had been resuscitated with infu- sion of unheated crystalloids and blood products [31]. Its occurrence was associated with a 4–41 times higher risk of intraoperative mortality [26, 29, 30, 32]. The inci- dence of hypothermia increases with higher injury severity scores and worsening degrees of shock. The association between hypothermia and mortality has been 4 The Open Abdomen: Balancing Pathophysiologic Benefts and Risks in the Era 59 reported to be stronger among those with core temperatures <33°C or who were diffcult to rewarm than those who remained warm or could be timely rewarmed [29, 32]. Although it would be predicted that the incidence of hypothermia would decline as resuscitation practices abandon infusion of large volumes of crystalloid fuids, even more recent series have reported development of severe hypothermia in injured patients [33].

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A brief sensory and motor neurologic examination is performed by the attending surgeon and general anesthesia is induced purchase 15mg lansoprazole otc. The Flexible Intubation Scope in Airway Management In 1967 purchase generic lansoprazole on line, the technique of fiberoptic-aided intubation was first performed using a choledochoscope in a patient with Still disease (idiopathic cheap lansoprazole 30 mg mastercard, adult-onset arthritis) cost of lansoprazole. With advancements in imaging technology, the fragile optical17 strands of fiberoptic scopes are now giving way to video imaging via distally mounted cameras on the same flexible shafts. These flexible (fiberoptic and video) intubation scopes are the most versatile tool available for situations when it is difficult or dangerous to create a line of sight to the glottis. There are, however, many clinical situations in which the flexible intubation scope can be of unparalleled aid in securing the airway. Unfortunately, clinicians rarely employ alternative techniques until a difficult situation arises. As with any critical competency, mastery of these techniques involves gaining and maintaining skills through use in routine airway management. Although flexible scope-aided intubation is a versatile and vital technique, there are several pitfalls, the most common of which are listed in Table 28-20. Because the optical elements are small (the objective lens is typically 2 mm in diameter or smaller), minute amounts of airway secretions, blood, or traumatic debris can hinder visualization. Administration of an antisialagogue (as discussed earlier) will produce a drying effect, but caution should be taken in patients who may not be able to tolerate an increase in heart rate. Vasoconstriction of the nose using topical oxymetazoline, phenylephrine, or cocaine reduces the chances of nasal bleeding if this route is chosen. If an awake flexible scope intubation is planned, the patient must be able to cooperate—a “quiet” airway, with little motion of the head, neck, tongue, and larynx, is vital to success. Finally, because flexible scope-aided intubation can require significant time (especially if the clinician is not facile 1973 with the device), hypoxia or impending airway loss is a contraindication and a more rapid method of securing an airway (e. It should also be mentioned that any methods used for tracheal intubation in the asleep patient can also be employed for awake intubation. Figure 28-25 The flexible intubation scope may be useful for diagnosis and therapy below the level of the vocal ligaments, including examination of bronchial segments and pulmonary toilet. A: Laryngeal web found in an asymptomatic patient who had had one previous tracheal intubation. Elements of the Flexible Intubation Scope The classic fiberoptic bronchoscope is an innately fragile device with both optical and nonoptical elements. The fundamental element consists of a 60- cm-long glass–fiber bundle (10,000–30,000 fibers per bundle) running the length of the insertion cord. Each fiber is 8 to 12 microns in diameter and is coated with a secondary glass layer termed cladding. Broken fibers, which can easily occur with bending of the insertion cord, entrapping of the cord in other equipment, or dropping the fiberoptic bronchoscope, are readily apparent as missing pixels in the image. These are typically just a nuisance until the number of broken fibers interferes with the visual field. A single-use version of this technology is available (aScope 3, Ambu, Ballerup, Denmark; Fig. Along with imaging elements, the insertion cord contains an accessory 1974 lumen or “working channel”: a lumen, up to 2 mm in diameter, which travels from the distal tip to the handle. In general, flexible intubation scopes that are less than 2 mm in external diameter (e. Table 28-19 Contraindications to Flexible Scope Intubation The distal end of the insertion cord is hinged for movement. Two wires, traveling from the control lever in the handle down the length of the insertion cord, control the movement of the distal tip in the sagittal plane. Coronal plane movement is accomplished by a combined use of the control lever and rotation of the entire flexible intubation scope (from handle to distal end). It is key to keep the insertion cord completely straight as this maximizes rotational control by ensuring that rotation of the hand piece translates to identical rotation of the distal tip. In the fiberoptic devices, illumination of the objective is provided by one or two noncoherent bundles of glass fibers that transmit light from the handle to the distal tip. The light is provided either by a cord that emerges from the handle and is inserted into an endoscopic light source or may be provided by a portable battery-operated light source on the handle. Table 28-20 Common Reasons for Failure of Flexible Scope Intubation 1975 Figure 28-26 The Ambu aScope 3 single-use flexible intubation scope. Apart from the delicate optics, there are cameras, recorders, light sources, and a variety of disposable adjuncts that are typically required. Dedicated wheeled carts, designed to carry equipment in a functional arrangement, are often utilized. Use of the Flexible Intubation Scope The flexible intubation scope is held with the thumb over the control lever and the index finger poised over the working channel valve. The contralateral hand is used to steady and hold the insertion cord at the level of the patient. An experienced endoscopist will recognize that the fine control required for steadying the bronchoscope while making minute directional adjustments and advancing it through the airway is where the art of endoscopy lies. This is most thoroughly described with flexible scope-aided intubation, for which it occurs in 20% to 30% of attempts. The nasal tube is softened in warm saline or water199 and well lubricated prior to insertion. While mandibular advancement and/or tongue extraction typically suffice, a variety of oral airways designed to facilitate flexible scope orotracheal intubation are commercially available. These devices function to provide a clear visual path from the oral aperture to the hypopharynx, keep the bronchoscope and tracheal tube midline, prevent the patient from biting the insertion cord, and provide a clear airway for spontaneous or mask ventilation. Figure 28-28 Intubating oral airways: (A) Ovassapian, (B) Berman and (C) Williams intubating oral airways. The flat lingual surface of the airway affords lateral and 1978 rotational stability. Both the Williams and the Berman airways were designed for blind orotracheal intubation. These airways have a smaller profile than the Ovassapian airway, but tend to have less rotational stability. The Berman airway addresses this problem with a split along the length of one side. After successful navigation past the tongue (whether facilitated by tongue extraction, mandibular advancement, or an intubating oral airway), the endoscopist visualizes the vocal folds. If glottic closure, gag, or coughing occurs, the operator can choose to apply local anesthetic through the working channel, administer more intravenous sedation, withdraw the scope and reinforce airway analgesia, or advance the scope into the larynx without further preparation. In the elective scenario, there is likely to be time for additional airway preparation, whereas in the face of impending respiratory arrest, patient discomfort may need to be tolerated. Once the larynx is entered, the flexible scope is advanced until the carina is visualized. Simply having the flexible scope enter the trachea does not guarantee that the intubation will be successful; hang-up and accidental scope withdrawal (via coughing or inattention) may still occur. Therefore, a patient with a critical airway should not be induced with a general anesthetic until intratracheal tube placement is confirmed. The primary literature contains a number of variations and adjuncts to flexible scope-aided intubation. Table 28-21, which is not meant to be exhaustive, lists several of these techniques. His maximal interincisor gap is 5 cm, thyromental distance is 7 cm, and his oropharyngeal view is a Samsoon– Young class 2. As cricoid pressure is held (Sellick maneuver), a hypnotic and succinylcholine are administered. Macintosh 4 and Miller 3 blades are utilized without improvement of the glottic view. Oxygen saturation has fallen from 100% to 92% and facemask ventilation is initiated with maintenance of cricoid pressure. Placement of an oral airway, chin and jaw lift, two-person ventilation, and reduction in the degree of cricoid pressure do not result in adequate mask ventilation. Even64 in cases of regurgitation, pulmonary aspiration is a rare event and a60 secondary concern to life-threatening hypoxemia. Case 4: Deviation from the Difficult Airway Algorithm Thirteen hours after admission to the intensive care unit, a 76-year-old woman with head, neck, and facial trauma from a motor vehicle accident is noted to have progressive decline in her level of consciousness and respiratory effort. On examination, there appears to be an adequate interincisor gap and thyromental distance, but the oropharyngeal view and cervical range of motion cannot be evaluated.

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