Category Archives: Ultrasound

Sonographic bits and bobs

Insertion of chest drains

The UK National Health Service’s National Patient Safety Agency published a report entitled ‘Risks of chest drain insertion’, reporting 12 deaths and 15 cases of serious harm related to chest drain insertion over a three year period. They issue the following recommendations under the title ‘For IMMEDIATE ACTION by the NHS and independent sector – Deadline for ACTION COMPLETE is 17 November 2008’:
Clinical governance leads in local organisations should audit current practice and develop local policies to ensure:

  • Chest drains are only inserted by staff with relevant competencies and adequate supervision
  • Ultrasound guidance is strongly advised when inserting a drain for fluid
  • Clinical guidelines are followed and staff made aware of the risks
  • Identify a lead for training of all staff involved in chest drain insertion
  • Written evidence of consent is obtained from patients before the procedure, wherever possible
  • Local incident data relating to chest drains is reviewed and staff encouraged to report further incidents

Chest drains: risks associated with the insertion of chest drains
National Patient Safety Agency

Appendicitis policy

The American College of Emergency Physicians has produced a policy entitled: ‘Critical Issues in the Evaluation and Management of Emergency Department Patients With Suspected Appendicitis

It contains the following questions and recommendations:

1. Can clinical findings be used to guide decisionmaking in the risk stratification of patients with possible appendicitis?

Level B recommendations. In patients with suspected acute appendicitis, use clinical findings (ie, signs and symptoms) to risk-stratify patients and guide decisions about further testing (eg, no further testing, laboratory tests, and/or imaging studies), and management (eg, discharge, observation, and/or surgical consultation).

2. In adult patients with suspected acute appendicitis who are undergoing a CT scan, what is the role of contrast?

Level B recommendations. In adult patients undergoing a CT scan for suspected appendicitis, perform abdominal and pelvic CT scan with or without contrast (intravenous [IV], oral, or rectal). The addition of IV and oral contrast may increase the sensitivity of the CT scan for the diagnosis of appendicitis.

3. In children with suspected acute appendicitis who undergo diagnostic imaging, what are the roles of CT and ultrasound in diagnosing acute appendicitis?

Level B recommendations.
1. In children, use ultrasound to confirm acute appendicitis but not to definitively exclude acute appendicitis.
2. In children, use an abdominal and pelvic CT to confirm or exclude acute appendicitis.
Level C recommendations. Given the concern over exposing children to ionizing radiation, consider using ultrasound as the initial imaging modality. In cases in which the diagnosis remains uncertain after ultrasound, CT may be performed.

The full document contains a helpful summary of existing literature on clinical scoring systems and laboratory investigations, including positive and negative likelihood ratios for various tests.

Fetal ultrasound safe

From the UK’s Health Protection Agency website:

The independent Advisory Group on Non-Ionising Radiation (AGNIR), which reports to the Health Protection Agency, has reviewed the latest scientific evidence on the health effects of ultrasound (frequencies above 20 kilohertz) and infrasound (below 20 Hz).

The report finds that the available evidence does not suggest that diagnostic ultrasound affects mortality of babies during pregnancy or soon after birth. The evidence also does not suggest any effect on childhood cancer risk. There have, however, been some unconfirmed reports suggesting possible effects on the developing nervous system – for instance, on handedness of the child.

AGNIR concluded that there is no established evidence that diagnostic levels of ultrasound are hazardous. However, further research is needed to determine whether there are any long-term adverse health effects, especially following exposure of the unborn child.

Differentiating arteries from veins

In a letter to Critical Care Medicine, ultrasound legend Michael Blaivas reminds readers that during ultrasound-guided central venous catheterisation, an additional technique for differentiating the common carotid artery from the internal jugular vein: pulse-wave doppler.

Image reproduced with kind permission of Dr Blaivas

Blaivas states: “The left panel shows a classic arterial tracing from the common carotid artery with a normal velocity. The right panel shows the vessel of choice on the same patient: the right internal jugular vein. The image shows a slightly chaotic venous tracing from the jugular. This a common appearance and is markedly different from the waveform of the carotid.”

Posterior vessel wall penetration by needles during internal jugular vein central catheter placement using ultrasound guidance: is that a real danger? Author’s Reply.
Crit Care Med. 2010 Feb;38(2):736-7