Ultrasound Clarifies Unexplained Hypotension
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14 Cardiovascular Medicine FAMILY P RACTICE N EWS • June 1, 2006 Ultrasound Clarifies Unexplained Hypotension Search for fluid in the peritoneal cavity or around three ultrasound views: a right upper is beating vigorously, that the left ventri- quadrant view, the same as is used for a fo- cle appears to be filling, and that there is the heart; rule out gross cardiac abnormalities. cused assessment with sonography for no pericardial effusion. trauma, or FAST, examination; a cardiac The abdominal view follows the aorta BY TIMOTHY F. KIRN might be used. They included a 24-year-old assessment with a subxiphoid or paraster- all the way down, from substernum to the Sacramento Bureau female who might have a ruptured ectopic nal long axis view; and an abdominal view. bifurcation, he said. As with the in- pregnancy, a cancer patient undergoing The right upper traperitoneal find- S OUTH L AKE TAHOE, CALIF. — treatment who could have pericardial ef- quadrant view— ‘If you find free fluid, an ings, evidence shows Bedside ultrasound should be used in the fusion, and a 60-year-old patient with a sys- which looks for fluid that most abdominal emergency department for patients with tolic blood pressure of 70 mm Hg who in the peritoneal cav- effusion, or an [abdominal aortic aneurysms as- undifferentiated hypotension, Dr. John S. might have an aortic aneurysm. ity, in Morison’s aortic aneurysm], I sociated with hy- Rose said at an emergency medicine con- Because unexplained hypotension is po- pouch between the potension are appar- ference sponsored by the University of tentially life threatening, one doesn’t usu- liver and kidney—is guarantee you are going to ent on ultrasound, California, Davis. ally use restraint in ordering tests and not always sensitive in change the course on that and they are almost The device can help identify three ma- studies in these cases, Dr. Rose said. And a trauma patient with never missed in the jor physical causes of hypotension: fluid in often there is no time to trundle the pa- limited bleeding. But patient.’ emergency depart- the peritoneal cavity, fluid around the tient off to some other department for it will be in the pa- ment. heart or gross cardiac abnormalities, and imaging studies. tient who has lost enough blood from the Each of these assessments can be ac- an abdominal aortic aneurysm, said Dr. “We do a lot of empiric things when circulatory system to be hypotensive, and complished extremely quickly, and none Rose of the department of emergency they come in sick, so why not add [an ul- evidence bears this out, Dr. Rose said. needs a special transducer, he added. medicine at UC Davis Medical Center, trasound exam] on top of it?” he said. The cardiac assessment, which Dr. Rose “If you find free fluid, an effusion, or an Sacramento. “You can still do a comprehensive eval- calls a “limited echo,” is practical because [abdominal aortic aneurysm], I guarantee “Ultrasound really will change your uation. The purpose behind the exam is it does not require extensive expertise, he you are going to change the course on that practice, not just in the trauma setting,” just to think about the three reversible said. It is a procedure that could be taught patient,” Dr. Rose said. “You are going to said Dr. Rose who described some hypo- causes that you can find with ultrasound.” to an emergency physician in half an hour. do something different. This is not just for thetical situations in which ultrasound Dr. Rose’s proposed exam consists of One is simply looking to see that the heart ‘I’d like to know.’” ■ CPR Guidelines Specialized for Lone Pyridostigmine Raises Rescuers of Children and Adults Standing BP in Orthostatic Hypotension BY KATE JOHNSON However, he said studies show that most efforts at Montreal Bureau CPR—even when given by health care professionals— yridostigmine significantly improves standing blood are still inadequate, involving too few chest compres- Ppressure in patients with orthostatic hypotension, and C HICAGO — The American Heart Association’s re- sions, compressions that are too weak, too many ven- it does so without worsening supine hypertension, re- newed emphasis on compression versus ventilation in tilations, and too many interruptions. ported Dr. Wolfgang Singer and his associates at the Mayo its latest cardiopulmonary resuscitation guidelines folds There is strong evidence pointing to the importance Medical Center, Rochester, Minn. children and adults into the same category when only of optimizing chest compressions, even at the expense Midodrine is the only drug previously shown in a one rescuer is present. of ventilation, he said. In fact, some studies suggest that blinded trial to improve orthostatic hypotension. But mi- In the hands of a lone rescuer, regardless of whether excessive ventilation might actually be leading to life- dodrine and other adrenergic agonists aggravate supine it is a layperson or a health care provider, children of all threatening hyperventilation-induced hypotension. A re- hypertension, “a major problem” in these patients be- ages (excluding newborns) should be treated using a 30:2 cent paper suggested that unrecognized and inadvertent cause their blood pressure fluctuates widely throughout compression-ventilation ratio, said Dr. Robert Hickey, hyperventilation could be contributing to the current- the day. Adrenergic agonists also raise the risk of intra- one of the authors of the guidelines, past chair of AHA’s ly dismal survival rates from cardiac arrest (Circulation cerebral hemorrhage, the investigators said. pediatric subcommittee, and chair of the Emergency 2004;109:1960-5). Dr. Singer and his associates assessed the effects of pyri- Cardiovascular Care Committee of the AHA. “Even if you do it right, there is a loss of coronary dostigmine, an anticholinesterase agent, in a study of 58 pa- A ratio of 15:2 is advised if perfusion pressure each time you tients with neurogenic orthostatic hypotension. The 30 men there are two trained (not lay) ‘Not enough people get CPR, stop to do a ventilation,” Dr. Hick- and 28 women had associated multiple system atrophy (17 rescuers present. “In children, res- ey said. “This is what fuels argu- patients), pure autonomic failure (15), diabetic autonomic cue breaths are more important and not enough people who ments for chest compression neuropathy (11), autoimmune autonomic neuropathy (9), partly because they largely have get CPR get good CPR.’ only.” or unspecified neurogenic orthostatic hypotension (6). asphyxial arrest,” he said in an in- Chest compressions should take On sequential days, the subjects took either oral place- terview at a meeting sponsored by the American Col- priority even over defibrillation, he added. One study bo, 60 mg of pyridostigmine alone, pyridostigmine plus lege of Emergency Physicians. showed an improved survival rate of 22% in patients a subthreshold dose of midodrine (2.5 mg), or pyri- Another pediatric specification of the guidelines is when defibrillation was delayed until after the initiation dostigmine plus low-dose midodrine (5 mg). that cuffed endotracheal tubes are as safe as uncuffed of chest compressions, compared with a 15% survival Pyridostigmine alone or with midodrine alleviated or- ones for infants (except newborns) and children in the rate among patients whose chest compressions fol- thostatic hypotension, compared with placebo. The blood hospital setting—as long as rescuers use the correct lowed defibrillation (JAMA 2003;289:1389-95). The same pressure fall upon standing was 27.2 mm Hg with pyri- tube size and inflation pressure, and verify tube posi- study showed that among patients with more than a 5- dostigmine plus 5 mg midodrine, compared with a fall of tion, he said. In fact, cuffed tubes may even be prefer- minute delay in rescue response following cardiac arrest, 34.0 mm Hg for placebo. able under certain circumstances, such as poor lung immediate defibrillation resulted in only a 4% survival Although the mean improvement in standing blood compliance, high airway resistance, and large glottic air rate, compared with a 22% survival rate in those who pressure was modest, a small increase appears to suffice leak, he said. had chest compressions before defibrillation. in alleviating symptoms. “Symptomatic improvement in Dr. Hickey said the most important overall message Dr. Hickey added that high-dose epinephrine is not some individuals was dramatic,” the researchers said in the new guidelines (Circulation 2005;112 [24 Sup- recommended in children, based on a study showing (Arch. Neurol. 2006;63:www.archneurol.com [doi.10. pl.]:IV1-203)—for both children and adults—is the re- that it did not improve return of spontaneous circula- 1001/archneur.63.4.noc50340]). newed focus on cardiopulmonary resuscitation (CPR). tion and resulted in worse 24-hour survival (New Engl. Most patients chose to continue taking pyridostig- “Not enough people get CPR, and not enough people J. Med. 2004;350:1722-30). mine. Of the 29 patients who were available for follow- who get CPR get good CPR,” said Dr. Hickey, profes- In neonatal resuscitation cases, current recommen- up 1-2 years later, 20 (69%) were still taking it. And of sor of pediatrics at the University of Pittsburgh and at- dations no longer advise intrapartum oropharyngeal those 20 patients, 17 (85%) “were extremely satisfied” tending physician in the division of pediatric emergency suctioning for infants born after meconium staining of with the medication and rated their orthostatic symptoms medicine at Children’s Hospital of Pittsburgh. amniotic fluid, he said. Endotracheal suctioning imme- as moderately to markedly improved. Ten patients re- The new guidelines stipulate that either one or two diately after birth for infants who are not vigorous is ported an increased energy level, said Dr. Singer. hands can be used for chest compressions in children. now recommended, Dr.