M2E Too! Mellick's Multimedia EduBlog
E Too! Blog by Larry Mellick, MD, presents important clinical pearls using multimedia.
By its name, M2E Too! acknowledges that it is one of many emergency medicine blogs, but we hope this will serve as a creative commons for emergency physicians.
Wednesday, July 02, 2014
Looks can be deceiving. I was not supposed to have a difficult airway, but we found out the hard way that wasn’t true. I was about to undergo an exploratory laparotomy for suspected appendicitis in 1989, and my wife was adamant that an attending anesthesiologist perform my intubation. The anesthesiology resident at a large Midwest teaching hospital made a claim that I suspect many of us did as we advanced through training and began to feel procedurally invincible. He claimed that the attending anesthesiologist rarely did intubations, and that the residents who performed them daily were more prepared. Unaware of any unique issues with my airway and wanting to be a good patient, I didn’t attempt to override the resident.
I woke up from anesthesia with a swollen, bleeding, and extremely painful pharynx, and my right central incisor was abraded and roughened. We learned that the resident made four attempts before the attending took over and successfully placed the airway. The soft tissue injury to the pharynx resolved with time, and my dentist filed the tooth smooth again. Subsequent surgeries, however, included a successful bougie intubation and a not-so-pleasant awake intubation.
This May, my shoulder pain reached a point where I knew it was time for surgery again. My left rotator cuff muscle needed to be repaired, just like the right one had years before. Intubation methods were a necessary topic of conversation with my anesthesiologist again.
My “3-3-2” airway assessment is abnormal on two counts. Instead of three fingers, my mouth will only open to allow two and maybe part of a third finger between the upper and lower incisors. The second “3” is the distance between the mentum and the hyoid bone. This gives an idea of how much space is available for the tongue to be displaced during laryngoscopy. My facial anatomy appears fine in this regard. The “2” refers to the position of the larynx in relation to the base of the tongue. Two or more fingerbreadths between the hyoid bone and the upper anterior edge of the thyroid cartilage are ideal. This signifies that the larynx is located sufficiently beyond the base of the tongue. I barely get one fingerbreadth with this measurement. These two variances add up to a markedly anterior larynx and a difficult-to-visualize airway. I have never been told what my Cormack-Lehane classification is, but my Mallampati score is a Class II.
Visualization of Glottis: Cormack-Lehane Classification
Grade 1: Full view of glottis and vocal cords
Grade 2: Vocal cords and glottis are partially visible
Grade 3: Only epiglottis seen; glottis is not visible
Grade 4: Glottis and epiglottis are not visible
Visualization of Upper Airway: Mallampati Class
Class I: Faucial pillars, soft palate, and uvula visualized
Class II: Faucial pillars and soft palate visualized; uvula not seen (masked by tongue)
Class III: Only soft palate and base of uvula visualized
Class IV: Faucial pillars, soft palate, and uvula not visualized (only hard palate visualized)
The anesthesiologist who agreed to take my case chose a fiberoptic intubation using nebulized lidocaine, a Parker Flex-Tip endotracheal tube with the unique beaked tip, and the endoscope plastic oral airway guide. In fact, we agreed to make a teaching video of my procedure, even knowing it might not be pretty. It wasn’t. Everything the anesthesiologist did was technically correct. Unfortunately, the lidocaine nebulization failed to anesthetize my airway. That, however, was my fault. Instead of consistently inhaling the 4% lidocaine, I stopped multiple times to greet acquaintances in the operating room and to direct the filming of my video. My reward was vigorous coughing and bucking as the endotracheal tube and fiberoptic scope were inserted.
The intravenous midazolam also caused a short period of apnea, and it was a little unnerving to listen to the pulse oximetry monitor alarm drop in pitch when I reviewed the video later. I couldn’t actually tell how low my oxygen saturation went, but the oxygen was turned up, and the first reported reading was of 93%. Thankfully, I have no memory of these events.
The truth is that events like this happen all the time despite our best-laid plans, and they are the substance of life in the ED that keeps us simultaneously on our guard (paranoid) and humble. I love the video because it shows a few of the realities of difficult airway management that can be instructional for learners. Click here to watch a video of the interscalene brachial plexus block used for my shoulder surgery.
Have you ever had a patient with a difficult airway like mine? How did you manage it? What tips do you have for difficult intubations?
Wednesday, June 04, 2014
Limb exsanguination is no longer the most common cause of preventable death on the battlefield because of emergency tourniquets. Hemorrhage control for wounds in the junction between the trunk and the limbs and in the neck are an obvious care gap, most commonly in the pelvic area, including the buttocks and groin proximal to the inguinal ligament. (US Army Med Dep J 2011 Apr-Jun:38.) Managing hemorrhagic shock also requires support of central aortic pressure to maximize perfusion of the brain and heart and to control bleeding effectively.
Noncompressible torso hemorrhage is recognized as the leading cause of death in trauma, but definitive hemorrhage control has been challenging. A review of combat casualties from 2001 to 2011 showed that the most common sites of lethal hemorrhage were truncal (67.3%), junctional (19.2%), and peripheral-extremity (13.5%). (J Trauma Acute Care Surg 2012;73[6 Suppl 5]:S431.)
The direct application of pressure over the distal aorta with an abdominal tourniquet and the insertion of a resuscitative endovascular balloon to occlude the aorta (REBOA) has recently come to the forefront as a potential life-saving option. The problem is bleeding from noncompressible vascular injuries. Traumatic or iatrogenic injuries to the common iliac, external iliac, internal iliac, profunda femoral, and superficial femoral can cause bleeding that is extremely difficult to control. (J Cardiovasc Surg (Torino) 2012;53:495.) Exsanguination from one of these vessels can occur in minutes or even seconds.
Pulsed-wave Doppler measurements have documented that blood flow to the common femoral artery can be stopped by applying direct pressure over the distal abdominal aorta or proximal iliac artery. (Prehosp Disaster Med 2006;21:379.) A number of reports have now documented the ability to stop blood flow to these major vessels with the Abdominal Aortic and Junctional Tourniquet (AAJT) and the REBOA. (Mil Med 2013;178:1196; J Trauma Acute Care Surg 2013;75:122; J Trauma Acute Care Surg 2013;75:506.) Major trauma center experience with REBOA suggests that it is feasible and effective for proactive aortic control in patients with end-stage shock from blunt and penetrating mechanisms. (J Spec Oper Med 2013;13:1.) Likewise, real-life experience with the AAJT also suggests that it can save lives. (J Spec Oper Med 2013;13:1; Surgery 2011;150:400.)
The AAJT and REBOA are relatively new concepts in emergency medicine, and their potential benefits and roles in managing life-threatening bleeding remain untapped to a significant degree. A respectable amount of research has been done for these tools and the FDA has approved several different applications of the AAJT, so it’s time to get broader clinical and research experience with them.
The AAJT has other applications besides inguinal and groin hemorrhage. The FDA approved it for life-threatening axillary hemorrhage, and it has been used off-label for life-threatening neck hemorrhage.
But what about using the AAJT or REBOA instead of cross-clamping the aorta when an open thoracotomy is performed? One animal study specifically looked at the use of REBOA for that purpose. (Can Med Assoc J 1964;91:128.) The AAJT would obviously occlude the aorta lower than the thoracic diaphragm cross-clamping location typically used during open thoracotomy, but cross-clamping the aorta during an open thoracotomy has been fraught with difficulty and plagued by operator inexperience. Many an esophagus has been inadvertently cross-clamped, and the traumatic injury to the aorta and its branching vessels from dissection and cross-clamping can be significant. The lower-placed AAJT would not occlude blood flow to the kidneys and the superior mesenteric artery, but maybe it’s not a bad idea to preserve blood flow to the kidneys and mesentery in addition to the brain and heart.
The biggest drawbacks to the REBOA are the technical skills required for insertion and the actual time it takes to insert the balloon. I want something fast when my patient is hemorrhaging uncontrollably, and that is where the AAJT fills the bill: it can be applied in less than 60 seconds. It’s possible these two tools can be used together effectively, with the AAJT being applied immediately to allow additional time for REBOA placement.
REBOA for stopping uncontrolled bleeding in pelvic fractures has been reported as quite effective. Again, it would be great to see some experience with the application of the AAJT for that same indication. Researchers reported in 1964 that compression of the aorta with the heel of the hand just above the bifurcation of the common iliac arteries was an effective way of controlling catastrophic pelvic hemorrhage during laparotomy. (Ann Emerg Med 2013 Oct 23; doi: 10.1016/j.annemergmed.2013.09.026.) More recent reports describe external manual compression for abdominal bleeding associated with penetrating injuries and ruptured abdominal aortic aneurysms. (J Anesth 2002;16:164; Obstet Gynecol 2014;123:804.) Pelvic binding and the AAJT might slow blood loss significantly in pelvic fractures.
Postpartum hemorrhage is another life-threatening emergency that can occur after a Caesarean section or vaginal delivery. It is one of the most common obstetric maternal complications, and is responsible for approximately half of severe maternal morbidity. (Transfusion
2014 Mar 12; doi: 10.1111/trf.12550.) Worldwide, postpartum hemorrhage is a common etiology of maternal death, and uterine atony is the major associated cause. (WHO Guidelines; http://bit.ly/1nECNO7
.) External manual compression of the aorta is a common treatment for life-threatening post-partum hemorrhage. (Anaesth Intensive Care
1994;22:571.) A commonly referenced case report describing successful management of a hemorrhaging patient with this technique was published in 1994. (Circulation
1993;88[4 Pt 1]:1916.) Again, here is another condition where it seems the AAJT could play a life-saving role in slowing uterine bleeding while other interventions are being started.
Applying the abdominal tourniquet during CPR has been discussed as one way to shunt blood flow selectively to the heart and brain, meeting CPR’s goal of maintaining blood flow to the vital organs until the heart can once again function independently. Aortic compression to augment cardiopulmonary resuscitation has been written about for decades. The results were variable, though, and a number of well-done papers demonstrated improved resuscitation parameters and outcomes when the aorta was occluded during CPR. (Am J Emerg Med 2002;20:453; Resuscitation 2001;50:319; Resuscitation 1999;40:171; Resuscitation 2011;82:1087; Resuscitation 2007;75:515; Crit Care Med 1997;25:1003.)
Applying the AAJT during CPR is a study that simply must be done. A significant step forward will have occurred in advanced cardiac life support if a distinctly positive outcome similar to the animal studies is found.
Both these tools can save lives for a wide spectrum of different life-threatening conditions. Unfortunately, the AAJT and the REBOA are currently relatively unknown and not being used. Emergency medicine and trauma programs need to include training in how to apply the AAJT and how to insert the REBOA. And, of course, we need increased research and assessment of various clinical applications.
Additional information about the Abdominal Aortic Junctional Tourniquet can be found at http://www.speeroptech.com/.
Dr. Mellick disclosed that he has no conflicts of interest related to the AAJT, but that the chairman of his department, Richard Schwartz, MD, is one of its inventors.
Thursday, May 01, 2014
I don’t have a problem with lumbar punctures in febrile neonates. In fact, my son ended up with three lumbar punctures before aging out of the febrile seizure protocols. I do have a problem, however, with doing unnecessary spinal taps. The emotional stress of a neonatal LP on parents is significant, and the physical stress of the procedure on the infant is also substantial.
The pain of the needle and the unique restraint required for the procedure are also potentially problematic. The pain of the needle can be minimized by EMLA cream (eutectic mixture of local anesthetics [lidocaine and prilocaine]) and local anesthesia. The risk of patient hypoxia is a well-recognized complication when scrunching a baby into a lateral, recumbent fetal position. No matter your level of experience, a number of traumatic taps will unavoidably occur (10-35%). (Pediatr Emerg Care 2011;27:1057.)
Even though the red and white blood cell counts can work with various formulas, the abnormal cell counts and the Gram stain’s crowded field leave a degree of diagnostic uncertainty in the end.
Controversy exists on this topic. Some providers feel strongly that lumbar punctures should be performed on every febrile infant under 90 days of age. Others, including many pediatricians, feel confident in assessing individual risks and recommending lumbar punctures on a case-by-case basis. (JAMA 2004 10;291:1203.) Neonates under 30 days old are placed in a separate category by most studies. Blood, urine, and CSF cultures are recommended for neonates, as are hospital admission and antibiotic therapy with a combination of ampicillin and a third-generation cephalosporin or gentamicin. Surprisingly and contrary to my perception, recent research shows that even the guidelines for infants under 28 days old are not followed rigorously. In fact, one in six febrile neonates are discharged from pediatric emergency departments after varying degrees of laboratory evaluation and antibiotic treatment. (Pediatrics 2014;133:187.)
Is it possible to identify clearly which febrile infant has a virus and which has a serious bacterial infection? A number of risk assessment protocols have been published and validated. The Boston, Philadelphia, and Rochester protocols are most commonly used, and the Rochester protocol does not mandate lumbar puncture as part of the evaluation. (Pediatrics 1994;94:390.)
The Rochester criteria also recommend admission for low-risk children whose parents were not mature, who are socioeconomically unstable, who are not within 30 minutes of the hospital, who could not return in 24 hours, or who did not have a car, thermometer, or telephone.
A review of the literature suggests that it is possible to avoid mindlessly performing a lumbar puncture on every febrile neonate. Consider the following.
Most are viral infections (approximately 90 percent): Viral infections are by far the most common cause of febrile illness in these infants: urinary tract infections, bacteremia, and very rarely meningitis occur in descending order. A 2012 retrospective study by Morley et al. attempted to determine the rates and the etiology of bacterial infection in children under 2 months during the vaccination era. In children younger than 28 days, 2.7 percent of blood, 10.7 percent urine, and zero percent (range 0.0-3.9%) of cerebrospinal fluid cultures were positive. In children 29 to 60 days, 1.5 percent of blood, 8.5 percent of urine, and 1.7 percent of CSF (range 0.0%-5.0%) cultures were positive. (Pediatr Emerg Care 2012;28:125.)
Low risk and serious bacterial infections: Infants classified as low risk have low rates of serious bacterial infections. Huppler et al. demonstrated in their extensive review of the literature that the rates of serious bacterial infections in low-risk patients in retrospective and prospective studies using empiric antibiotic treatment were the same (2.7%), and were significantly different from the rate of serious bacterial infections in low-risk patients in prospective studies in which antibiotics were withheld (6/870 patients [0.67%]). (Pediatrics 2010;125:228.)
They noted that the low-risk criteria functioned best when used in prospective studies in which low-risk patients underwent observation alone and empiric antibiotic treatment was not an option. Urinary tract infections (false-negative urinalysis) and bacteremia will occasionally be missed, but multiple studies have shown that the risk of meningitis is extremely low. (Pediatrics 2010;125:228.) Low-risk, healthy-appearing infants did well without complications in various studies even when sent home and the infection was detected within 24 hours. The negative predictive value of the Rochester criteria is 98.9% with a 95% confidence interval of 97.2% to 99.6% for any serious bacterial infection, and 99.5% with a 95% confidence interval of 98.2% to 99.9% for bacteremia. (Pediatrics 1994;94:390.)
Meningitis: No cases of meningitis occurred in the five prospective studies that used observation alone without antibiotics (0/870 patients), according to the review article by Huppler et al. that looked at low-risk patients. Two cases of meningitis were found in 3114 (0.06%) patients classified as low risk in the prospective studies that treated all patients with antibiotics. The authors hypothesized that the meticulous assessment of study patients was affected when all patients were ultimately treated with antibiotics. (Pediatrics 2010;125:228.) Nevertheless, this information strongly suggests that the risk of meningitis is very small in low-risk infants who have been carefully evaluated.
The rate of meningitis is low even in high-risk patients: approximately 1-1.7 percent. (Pediatr Emerg Care 2012;28:125; Pediatrics 2004;113:1662.)
Viral testing and serious bacterial infections: Infants who test positive for a viral infection also have a significantly lower risk of having a low rate of serious bacterial infections. Again, however, the associated serious bacterial infections are primarily urinary tract infections with bacteremia; meningitis was almost nonexistent. A 2004 study by Byington et al. compared serious bacterial infections in infants with and without documented viral infections; a serious bacterial infection occurred in 4.2 percent of those with viral infections compared with 12.3 percent of infants without a confirmed viral infection. (Pediatrics 2004;113:1662.)
No cases of bacterial meningitis were detected in infants with viral infections and in six (0.67%) patients without an identified viral infection. Bacteremia occurred in five of 491 (1%) compared with 24 of 894 (2.7%) infants without an identified viral infection. Another study of serious bacterial infections found that infants with a positive RSV test had a 5.4 percent rate of urinary tract infections as compared with a 10.1 percent rate of UTIs in the RSV-negative infants. The risk of bacteremia (1.1% vs 2.3%; risk difference: 1.2%; 95% CI: -0.4% to 2.7%) or meningitis (0/251) as compared with RSV-negative infants did not achieve statistical significance. (Pediatrics 2004;113:1728.) Very similar numbers were described in another study that tested 1091 infants for influenza viruses. Again, statistical significance was not met, but none of the influenza-positive infants had positive blood cultures or meningitis, and urinary tract infections predominated as serious bacterial infections. (Pediatrics 2009;124:30.)
High risk with a virus: What about infants deemed high risk according to the Rochester criteria who have a documented viral infection? High-risk infants with a documented viral infection (HR+) have a lower risk of serious bacterial infection than high-risk infants without a viral infection (HR-). (Pediatrics 2004;113:1662.) The risk of a serious bacterial infection in HR+ infants (18/323 [5.5%]) was comparable with low-risk infants (9/289 [3.1%]). Importantly, the high-risk infants who were positive for a viral infection (N=324) had no cases of meningitis (0/324), 3.7 percent (15/324) had UTIs, and 0.92 percent (3/324) had bacteremia.
Hib and PCV immunizations: Immunizations for the common childhood illnesses don’t begin until 60 days of age. The Hib vaccine protects against Haemophilus influenzae type b, and the PCV vaccine protects against pneumococcus. Interestingly, it appears that these bad players are not a problem in the vast majority of febrile infants. These classic pathogens are essentially nonexistent, thanks to herd immunity. (Pediatr Emerg Care 2012;28:125.)
Disposition home: Low-risk infants over 30 days of age (carefully evaluated according to the Rochester criteria) with or without positive viral testing can be sent home without a spinal tap.
These suggestions can help safely avoid lumbar punctures in febrile neonates:
• Perform a meticulous physical examination and detailed history.
• Don’t rush the assessment. Spend time watching the infant and paying close attention to parental observations and concerns. Remember, a child is not considered low risk if he does not look well, regardless of laboratory findings.
• Assess risk for a serious bacterial infection by using one of several proven protocols. (The Philadelphia and Boston protocols are commonly used, but only the Rochester criteria allows for not doing a lumbar puncture if low-risk criteria are met.)
• If available, perform viral testing for the common viral agents such as respiratory syncytial virus and influenza. Even better, more expansive full respiratory virus panels are now available, and their price has become increasingly reasonable.
• Every infant should have blood and urine cultures sent off to the lab in addition to the complete blood cell count and urinalysis. Some institutions will add a CRP. Stool should be checked for fecal leukocytes, culture, and rotavirus if diarrheal illness is present. Consider a chest radiograph if a patient has respiratory symptoms and for the herpes simplex virus if he has vesicular skin or mouth lesions. Appropriate management is mandatory.
• Be sure your institution has an efficient system for tracking and reporting blood and urine cultures. Tracking cultures during the first 24 hours is critical to preventing missed serious bacterial infections. A culture-proven UTI can occur despite a normal urinalysis in 35-50 percent of these infants. (Pediatrics 1994;94:390.) The time needed to identify a true positive culture is under 24 hours for most cultures. (Ann Emerg Med 2000;36:602.)
The final disposition for low-risk infants managed without a lumbar puncture or antibiotics will be admission to the hospital for careful observation or discharge home with clear return precautions and close follow-up the following day. Admission to the hospital is more expensive, but some consider it the most risk-adverse approach. Admission would occur for low-risk infants without a lumbar puncture and without antibiotics. Other practitioners will feel compelled to perform an LP on every febrile neonate under 90 days, and will often start antibiotics as part of the admission process.
If hospitalization is chosen, 24 hours or less will be sufficient time for observation of most infants and for most cultures to become positive. (Ann Emerg Med 2000;36:602.) If you send home a low-risk patient without a spinal tap, it is essential to have confidence in the caregivers, provide clearly delineated return precautions, and ensure easy access to medical care with close follow-up the next day. (Pediatrics 1994;94:390.)
The bottom line is that a small risk of serious bacterial infection remains for even low-risk patients with a documented viral illness. Know ahead of time what level of risk you are comfortable accepting for your patients. Thankfully, the serious bacterial infection risk for meningitis is very, very low.
A spinal tap may no longer be avoided if the child is high risk without a documented viral infection. This video outlines three steps to maximize the success of infant spinal tap and to avoid the dreaded traumatic spinal tap. Antibiotics should not be given before the spinal tap. The rate of meningitis is quite low, so about 99 percent of spinal taps will fail to demonstrate bacterial meningitis, but it is possible that the spinal fluid will be sterilized if antibiotics are given before the spinal tap, and this uncertainty may contribute to an unnecessarily prolonged hospitalization when discharge after 24 hours of observation without antibiotics would have been appropriate.
Wednesday, April 02, 2014
I took a surprisingly enjoyable course in medical entomology as an undergrad at Ohio State University. Admittedly, decades later, the only things I remember from that course are that only four of the 4500 species of cockroaches are classified as pests: the German, Asian, American, and Oriental cockroaches.
The majority of cockroach species live in their natural habitats in woods, tropical forests, or deserts, but these four have taken up residence with humans and have become serious pests. They may have distinctly cosmopolitan names, but it is believed that they all started in Africa. Their mouths can chomp through cardboard, cloth, or paper to reach food. They contaminate everything they touch with their feces.
Dissemination of disease has not been well documented, but they are undeniably transporters of bacteria, viruses, fungi, and parasites. A review of the literature indicates that cockroaches have been accused of spreading leprosy, cholera, and more recently, the HIV virus. Multiple studies of the bacteria associated with or in cockroaches also have demonstrated a host of bacteria and parasites pathologic to humans. They are dirty, repulsive little bugs that feed on filth.
One of the first things I learned when we moved to the South was that cockroaches love temperate and hot climates. These nocturnal partiers love to hide in warm, dark places. Living proof is the number of patients I see presenting with cockroaches in their external ear canals. The prospect of something with spiny little legs and fluttering wings moving around in one’s external ear canal is enough to cause the most stoic among us to cringe.
Nevertheless, I recently had one young man present with a cockroach that had been in his ear for an entire week. It could have been worse: a cockroach was once discovered during a routine screening colonoscopy. (Endoscopy 2010;42[Suppl 2]:E209.) Removal of the dead, decaying carcass from my patient was piecemeal and not easy. (Click here and here to see videos of removal.)
The problem with the retrieval process is that the external ear canal is extremely sensitive and total anesthesia comes at an expense: multiple painful injections in an extremely sensitive area. Anesthesia of the ear can be attempted with bupivacaine or lidocaine injections, but the four-point injection at the external canal seems like torture of sorts. (See illustration below from Roberts & Hedges, Clinical Procedures in Emergency Medicine, 6th edition, Philadelphia: Saunders/Elsevier, 2014.) Attempts to anesthetize the ear with an otic solution containing antipyrine and benzocaine or viscous lidocaine are also less than ideal because topical medications have only minimal benefit.
What do you do when the cockroach or any insect in the ear is still alive? Some of the interventions you think would work actually don’t. Microscope oil, 2-4% lidocaine, viscous lidocaine, mineral oil, EMLA cream, and ethanol all work within 60 seconds. Auralgan, isopropanol, water, succinycholine, and hydrogen peroxide do not work.
My experience with cockroach extractions is that the cockroach always seems to come out piecemeal. Your forceps will bring out legs, thorax, etc., in various sequences. Removal techniques with catheter irrigation can also work. Make sure the catheter is inserted deep into the canal and past the insect. This ensures that the fluid will push out the culprit.
A little known fact is that cockroaches bite and can cause physical harm. (Int J Dermatol 2014;53:e277; Am J Forensic Med Pathol 1997;18:177; Int J Dermatol 1997;36:90.) I first saw evidence of that several years ago when a handicapped 45-year-old woman presented with abdominal pannus skinfold injuries reportedly from the family of German cockroaches found lining her underwear. She noticed the cockroaches in the drawstring of her underwear, and her family identified the species based on Internet pictures. The patient subsequently developed four abscesses that drained. She cleaned them out with hydrogen peroxide, salt water, and bleach. She took antibiotics donated by a friend because the redness was worsening. (See video.) Knowing that cockroaches are omnivores willing to nibble on human skin elevates their repulsiveness considerably.
Friday, February 28, 2014
The classic clinical presentation of infantile hypertrophic pyloric stenosis (IHPS) is an emaciated 3- to 6-week-old infant who has been experiencing immediate postprandial, nonbilious, projectile vomiting over a period of weeks. The infants remain hungry and demand to be re-fed after vomiting. Caucasian, full-term boys (4:1 to 6:1) tend to present with this condition most frequently, and these patients tend to be firstborns.
An olive-sized tumor can be felt to the right of the umbilicus, and this may best be palpable immediately after the infant has vomited. Visible peristaltic waves may also be noted. The infants are typically not otherwise ill-appearing, but they may be dehydrated with fretfulness, apathy, and loss of skin turgor. Click here to watch a video of a patient with pyloric stenosis.
The frequent and persistent vomiting puts these infants at risk for electrolyte abnormalities, specifically hypochloremia, hypokalemia, and metabolic alkalosis. Interestingly, the classic presentation of this condition would probably not include electrolyte abnormalities; they tend to be absent in the majority of patients studied. (Am J Emerg Med 1999;17:67; Pediatr Emerg Care 2013;29:465; J Pediatr Surg 1989;24:1250.) Significant electrolyte abnormalities tend to occur in infants undiagnosed for more than three weeks. Fortunately, infants are currently diagnosed earlier than in the past, and they tend to be less emaciated.
Normal laboratory values are the most common finding in hypertrophic pyloric stenosis, but it is clinically important to understand the electrolyte complications that can occur when a child is vomiting multiple times a day for weeks at a time. The loss of large amounts of gastric hydrochloric acid (HCL) results in the hypochloremic metabolic alkalosis. Renal potassium wasting appears to be the primary cause of the hypokalemia.
Another 5-week-old boy recently presented for prolonged vomiting. Sure enough, ultrasound of the gastric outlet demonstrated hypertrophy of the pylorus with a single wall thickness of 5 mm and increased length measuring up to 24 mm. The laboratory results were also notable. He demonstrated the classic findings of hypochloremic, hypokalemic metabolic alkalosis.
He also demonstrated hyperbilirubinemia, which turned out to be a great teaching point even for the old-timers. Hyperbilirubinemia is not uncommonly associated with IHPS, and is known as the icteropyloric syndrome. Unconjugated hyperbilirubinemia is more common than conjugated hyperbilirubinemia, and may be associated genetically with Gilbert syndrome. (J Pediatr 1990;117[1 Pt 1]:168; S Afr Med J 1986;69:446; Arch Dis Child 1999;81:301.)
Our ED was recently reminded that pyloric stenosis can occur in adults with exactly the same pattern of electrolyte abnormalities. The patient was a 34-year-old man with neurofibromatosis. His initial history did not confirm frequent episodes of vomiting, but his electrolyte pattern (see image below) made me think that his laboratory testing looked exactly like a pyloric stenosis patient. He later told us he had a history of intractable vomiting associated with gastric outlet obstruction secondary to pyloric strictures. Pyloric thickening in adults is associated with peptic ulcer disease, hypertrophic gastropathy, and carcinoma. (J Gastrointest Surg 2006;10:265.)
Hypochloremic, metabolic acidosis accompanied by hypokalemia is not present in every case of pyloric stenosis, but it can be helpful in confirming the diagnosis when it does occur. That goes for adults and infants.