Critical Care Obstetrics
SCOBSonography in Critical Care
OBstetrics
Critical Care Obstetrics
Learning Objectives
Background / Rationale
Cardiac Output Assessment
Pulmonary Assessment
Volume Assessment
FAST Scan
Systemic Vascular Resistance
Assessment
Critical Care Obstetrics
Background / Rationale
Maternal mortality rate in the U.S. is rising
Sonography can augment the clinical response to
nearly ALL of the leading causes
27.1
14
10.7
7.9
3.2
0 5 10 15 20 25 30
HEMORRHAGE
HYPERTENSIVE DISORDERS
SEPSIS
ABORTION
EMBOLISM
Percentage
Critical Care Obstetrics
Point-of-Care Ultrasound
FAST Scan
RUSH Protocol
Standard OB imaging
Fetal echocardiography
Novel sonographic techniques
Critical Care Obstetrics
Purpose
Application of Point-of-Care Sonographic
techniques to gain a deeper understanding of
physiologic changes among pregnant women
experiencing critical illness
Assess the utility of these adjunctive sonographic
techniques to augment clinical decision-making in
critical care scenarios
Critical Care Obstetrics
Cardiac Output
Assessment
Critical Care Obstetrics
Calculating End-Point Septal Separation (EPSS) of
the medial mitral leaflet using M-mode sonography
Parasternal Long Axis View
Place M-mode gate vertically to capture full medial mitral leaflet
and ventricular septum during a full cardiac cycle
LVEF = 75.5 -2.5(EPSS in mm)
LV
RV
LA
Ao
Mitral
ValveD Ao
Aortic
Valve
Ventricular
Septum
Critical Care Obstetrics
Calculating End-Point Septal Separation (EPSS) of the medial
mitral leaflet using M-mode sonography
Parasternal Long Axis View
Place M-mode gate vertically to capture full medial mitral leaflet and
ventricular septum during a full cardiac cycle
LVEF = 75.5 -2.5(EPSS in mm)
Biphasic M-Mode Wave
• E-wave (Early Diastolic
Excursion
• A-wave (Atrial Kick)
Critical Care Obstetrics
Calculating End-Point Septal Separation (EPSS) of the medial mitral leaflet using M-mode sonography Parasternal Long Axis View
Place M-mode gate vertically to capture full medial mitral leaflet and ventricular septum during a full cardiac cycle
LVEF = 75.5 -2.5(EPSS in mm)
Critical Care Obstetrics
Cardiac output: (heart rate x stroke volume)
In parasternal long axis view for LVOT measurement, measure
just above the aortic valve during systole
To measure VTI, use pulsed-wave Doppler in the apical 4-
chamber (just beneath left nipple / breast) view with the gate just
below the aortic valve
LVOT (mm)
Critical Care Obstetrics
Cardiac output: (heart rate x stroke volume)
In parasternal long axis view for LVOT measurement, measure
just above the aortic valve during systole
To measure VTI, use pulsed-wave Doppler in the apical 4-
chamber (just beneath left nipple / breast) view with the gate just
below the aortic valve
LV
RV
LVOT
Critical Care Obstetrics
Cardiac output: (heart rate x stroke volume)
Stroke volume = LVOT area x LVOT VTI
SV = π x [(LVOT diameter)/2]2 x VTI
VTI = velocity time integral manually traced using pulsed-wave
Doppler sampling of the LVOT
CO = SV x HR
SV = π x [(LVOT diameter)/2]2 x VTI
SV = 3.14 x [2.2 cm / 2]2 x 17.9 cm
SV = 67.4 cm
HR = 80 bpm
CO = 5,386 cm/min or 5.4 L/min
Critical Care Obstetrics
Cardiac output: (heart rate x stroke volume)
Stroke volume = LVOT area x LVOT VTI
SV = π x [(LVOT diameter)/2]2 x VTI
VTI = velocity time integral manually traced using pulsed-wave
Doppler sampling of the LVOT
Critical Care Obstetrics
Cardiac output: (heart rate x stroke volume)
Stroke volume = LVOT area x LVOT VTI
SV = π x [(LVOT diameter)/2]2 x VTI
VTI = velocity time integral manually traced using pulsed-wave Doppler sampling of the LVOT
Critical Care Obstetrics
Pulmonary
Assessment
Critical Care Obstetrics
Patient Positioning
Sonographer
scans from
patient right
Patient is
supine with
slight leftward
decubitus
position
Critical Care Obstetrics
Pneumothorax
Bedside sonography is more reliable than AP plain chest X-ray for pneumothorax detection
95-100% sensitivity & 91% specificity for detecting pneumothorax
Lyon M, Walton P, Bhalia V, et al. Ultrasound detection of the sliding
lung sign by prehospital critical care providers. Am J Emerg Med.
2012;30(3):485-88.
Lichtenstein DA, Meziere G, Lascois N, et al. Ultrasound diagnosis of
occult pneumothorax. Crit Care Med 2005;33(6)1231-38.
Critical Care Obstetrics
Pneumothorax
Place transducer on
anterior chest at the 2nd
or 3rd intercostal space
Air will rise to most
superior / anterior
portion of the chest
Critical Care Obstetrics
Pneumothorax
Pneumothorax is ruled-out
by any of the following
Sliding-lung sign
B-lines or lung rockets
Lung pulse
It’s ruled-in by identifying
gas / air within the pleural
space
Lichtenstein DA, Meziere G, Lascois N, et al. Ultrasound diagnosis of
occult pneumothorax. Crit Care Med 2005;33(6)1231-38.
Critical Care Obstetrics
Pneumothorax
Sliding-Lung Sign
Identify two ribs and the
bright pleural line beneath
To-and-fro sliding of the
pleural line
Synchronized with
respirations
No pneumothorax under
the US transducer
Rib RibPleural Line
Critical Care Obstetrics
Pneumothorax
Sliding-Lung Sign
Identify two ribs and the
bright pleural line beneath
To-and-fro sliding of the
pleural line
Synchronized with
respirations
No pneumothorax under
the US transducer
Critical Care Obstetrics
Pneumothorax
Lack of Sliding-Lung
Sign
Pneumothorax
Emphysema
Esophageal or contralateral
main-stem bronchus
intubation
Critical Care Obstetrics
Pulmonary Edema
Bedside sonography is
a reliable method for
accurate detection of
pulmonary edema
Easily repeated and
can monitor resolution
from diuretics
Noble VE et al. Ultrasound assessment for extravascular lung water
in patients undergoing hemodialysis. Time course for resolution.
Chest 2009; 135:1433-39.
Critical Care Obstetrics
Pulmonary Edema
Place transducer between
ribs (rib inter-space) at
most dependent portion of
lungs (posterior axillary
line just above diaphragm
bilaterally)
Fluid will fall to most
inferior / posterior portion
of the chest
Critical Care Obstetrics
Pulmonary Edema
Pulmonary Edema is
identified by B-Lines or
Lung Rockets
B-lines – hyperechoic
vertical laser-like beam
reaching far field of screen &
move in concert with lung
motion
Lung rockets – 3 or more B-
lines noted in inter-rib
spaces
Critical Care Obstetrics
Pulmonary Edema
Pulmonary Edema is
identified by B-Lines or
Lung Rockets
B-lines – hyperechoic
vertical laser-like beam
reaching far field of screen &
move in concert with lung
motion
Lung rockets – 3 or more B-
lines noted in inter-rib
spaces
Critical Care Obstetrics
Pleural Effusions
Place transducer between
ribs (rib inter-space) at
most dependent portion of
lungs (mid or posterior
axillary line just above
diaphragm bilaterally)
Fluid will fall to most
inferior / posterior portion
of the chest
Critical Care Obstetrics
Pleural Effusions
Plain Chest X ray
65% Sensitivity
81% Specificity
Lung Ultrasonography
97-100% Sensitivity
94-100% Specificity
Brogi E, Gargani L, Bignami E, et al. Thoracic ultrasound for pleural
effusion in the intensive care unit: a narrative review from diagnosis to
treatment. Crit Care. 2017;21:325.
Critical Care Obstetrics
Pleural Effusions
RUQ Mid-Axillary
Identify Liver,
diaphragm, and chest
wall
Dark fluid identified
above diaphragm
Lung seen moving
with respiration
Air identified within
the bronchioles as
bright
Critical Care Obstetrics
Volume Assessment
Critical Care Obstetrics
Stroke volume variation: (maximum SV – minimum SV)/mean SV
Using pulsed-wave Doppler at the left ventricular outflow tract (LVOT) over 10 seconds
Measure the peak systolic velocity of the highest wave and the smallest wave.
Measure the average of all the waves (can use the auto trace function to calculate) in the cardiac settings
LV
RV
LVOT
Critical Care Obstetrics
Stroke volume variation: (maximum SV – minimum SV)/mean SV
Using pulsed-wave Doppler at the left ventricular outflow tract (LVOT) over 10 seconds
Measure the peak systolic velocity of the highest wave and the smallest wave.
Measure the average of all the waves (can use the auto trace function to calculate) in the cardiac settings
>13% = Fluid Responsive
Zhang Z, Lu B, Sheng Z, et al. Accuracy of stroke volume
variation in predicting fluid responsiveness. J Anesth.
2011 Dec:25(6):904-16.
Critical Care Obstetrics
In sagittal plane just right of midline beneath the costal margin in the RUQ of the abdomen, identify the inferior vena cava (IVC)
Measure diameter of the IVC using M-mode or calipers at maximum diameter during inspiration and expiration at least 3 cm from diaphragm
Critical Care Obstetrics
Critical Care Obstetrics
In sagittal plane just right of midline beneath the costal margin in the RUQ of the abdomen, identify the inferior vena cava (IVC)
Measure diameter of the IVC using M-mode or calipers at maximum diameter during inspiration and expiration
Critical Care Obstetrics
FAST SCAN
Critical Care Obstetrics
Focused Abdominal Scan in Trauma
Blunt or penetrating
trauma to the
abdomen
Abdominal pain or
hemodynamic
instability in
pregnancy
Unexplained
hypotension
Critical Care Obstetrics
RUQ View
Morrison’s pouch –
the most dependent
portion of the
abdomen
Look for interface
between right
kidney and liver
Look above liver
beneath diaphragm
Critical Care Obstetrics
RUQ View
Morrison’s pouch –
the most dependent
portion of the
abdomen
Look for interface
between right
kidney and liver
Look above liver
beneath diaphragm
Critical Care Obstetrics
RUQ View
Morrison’s pouch –the most dependent portion of the abdomen
Look for interface between right kidney and liver
Look above liver beneath diaphragm
FREE FLUID BETWEEN R KIDNEY
AND LIVER
Critical Care Obstetrics
LUQ View
Interface of spleen
and left kidney
Must appear to be
in contact with each
other
Caution for fluid in
stomach which can
be misleading
Critical Care Obstetrics
LUQ View
Interface of spleen
and left kidney
Must appear to be
in contact with each
other
Caution for fluid in
stomach which can
be misleading
Critical Care Obstetrics
LUQ View
Interface of spleen and left kidney
Must appear to be in contact with each other
Caution for fluid in stomach which can be misleading
FREE FLUID BETWEEN L KIDNEY
AND SPLEEN
Critical Care Obstetrics
LUQ View
Critical Care Obstetrics
Supra-Pubic View
Midline sagittal just
superior to the
pubic symphysis
Best if bladder is full
Fan side-to-side
looking for anechoic
“wedges”
Critical Care Obstetrics
Supra-Pubic View
Midline sagittal just superior to the pubic symphysis
Best if bladder is full
Fan side-to-side looking for anechoic “wedges”
FREE FLUID ADJACENT TO THE
BLADDER
Critical Care Obstetrics
Systemic Vascular
Resistance
Assessment
Critical Care Obstetrics
Systemic vascular resistance (Both methods of calculation)
Resistance index using pulsed-wave Doppler of the dorsal branch of the radial artery
Hold transducer in sagittal plane at the base of the thumb
Pulsed-wave Doppler assessment of Resistance Index [(velocity during systole – velocity during diastole) / velocity during systole]
Also can calculate systemic vascular resistance separately to correlate
SVR = Mean Arterial Pressure (MAP) x 80/Cardiac output
Critical Care Obstetrics
Systemic vascular resistance (Both methods of calculation)
Resistance index using pulsed-wave Doppler of the dorsal branch of the radial artery
Hold transducer in sagittal plane at the base of the thumb
Pulsed-wave Doppler assessment of Resistance Index [(velocity during systole – velocity during diastole) / velocity during systole]
Also can calculate systemic vascular resistance separately to correlate
SVR = Mean Arterial Pressure (MAP) x 80/Cardiac output
Critical Care Obstetrics
Systemic vascular resistance (Both methods of calculation)
Resistance index using pulsed-wave Doppler of the dorsal branch of the radial artery
Hold transducer in sagittal plane at the base of the thumb
Pulsed-wave Doppler assessment of Resistance Index [(velocity during systole – velocity during diastole) / velocity during systole]
Also can calculate systemic vascular resistance separately to correlate
SVR = Mean Arterial Pressure (MAP) x 80/Cardiac output
Critical Care Obstetrics
Parameter
Finding Therapeutic Approach
Volume IVC Maximum Diameter
IVC Caval Index
Stroke Volume Variation
Low IVC diameter < 1.3 cm IVC caval index > 50%
SVV > 13%
IV Fluid Bolus (500 ml LR over 10 min) + Labetalol
• Low Volume
• High Cardiac Output
• Normal or Low SVR
• Predominantly Systolic BP w/normal PP
Normal IVC diameter 1.3 – 2 cm IVC caval index 25-50%
SVV 5-13%
IV Fluid Bolus (500 ml LR over 10 min) + Hydralazine
• Low Volume • Low or Normal Cardiac Output
• Normal or High SVR
• Predominantly Diastolic BP w/low or normal Pulse Pressure
High IVC diameter > 2 cm
IVC caval index < 25%
SVV < 5%
Labetalol Alone
• Normal Volume • High Cardiac Output
• Low or Normal SVR
• Predominantly Systolic BP w/normal or high
Pressure
Cardiac Output End-Point Septal Separation
for LVEF Calculation Cardiac Output = HR x SV
(SV = LVOT area x LVOT VTI)
Low LVEF < 50%
CO < 5 L/min
Nifedipine Alone
• Normal Volume
• Normal Cardiac Output • Normal SVR
• Either predominance & low or normal pulse
pressure
Normal LVEF 50-60%
CO 5-7 L/min
Hydralazine Alone
• Normal Volume • Low or Normal Cardiac Output
• High SVR
• Predominantly Diastolic w/low pulse pressure
High LVEF > 60%
CO > 7 L/min
Lasix 20 mg IV once + Labetalol
• High Volume • High Cardiac Output
• Low or Normal SVR
• Predominantly Systolic w/normal or high pulse
pressure
Systemic Vascular
Resistance Resistance Index @
Snuff Box PVR = MAP x 80/CO
Normal RI < 1
PVR < 1300
Lasix 20 mg IV once + Nifedipine • High Volume
• Normal Cardiac Output
• Normal SVR • Either predominance & low or normal pulse
pressure
High RI > 1
PVR > 1300
Lasix 20 mg IV once + Hydralazine
• High Volume
• Low Cardiac Output • High SVR
• Predominantly Diastolic w/low pulse pressure
Pulse Pressure (SBP – DBP)
Low (< 40 mmHg)
Normal (40-80 mmHg)
High (> 80 mmHg)
Predominant Type Systolic > 160 mmHg
Diastolic > 110 mmHg
Systolic
Diastolic