Comparison of Arm and Ankle Blood Pressure During Cesarean Delivery: A Blood Pressure Cuffs Pilot Study
Conditions: Supine Hypotensive Syndrome, Cesarean Section Complications, Anesthesia Complication
Sponsor: Ohio State University

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
1 
 
 
 
Protocol title: Comparison of Arm and Ankle Blood Pressure 
during Cesarean Delivery: A Blood Pressure Cuffs Pilot Study 
 
 
NCT#: 2020H0502 
 
 
 
IRB approval date: 14MAR2021 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
2 
Comparison of Arm and Ankle Blood Pressure during Cesarean Delivery: A Blood Pressure Cuffs 
Pilot Study 
 
BACKGROUND AND SIGNIFICANCE  
 
A literature search found the incidence of hypotension after subarachnoid block (SAB) varied between 7.4% 
and 74.1%,[1] while another recent publication discovered the incidence of hypotension to be 5.4%.[2] There 
is a large variation of definitions used for intraoperative hypertension (IOH) in anesthesia literature. The 
relationship between these definitions and the incidence of IOH is depicted in Figure 1.[3]  
 
￼
 
Figure 1. Incidences of hypotension after SAB and the definitions of hypotension 
 
In the last three decades, numerous interventions have been studied and implemented into our daily practice, 
such as pre-loading versus co-loading, phenylephrine versus ephedrine, and phenylephrine infusion versus 
intermittent boluses. In addition, the effectiveness of left uterine displacement (LUD) to improve blood flow 
and pressure remains unclear. Also, there are issues to be addressed on this regard, including:  
1. Poor placental perfusion from inadequate LUD due to the potential impact of supine hypotensive 
syndrome (SHS) secondary to aortocaval compression especially after SAB;  
2. Shivering during cesarean delivery (CD) resulting in inaccurate BP measurements, the incidence of 
shivering during CD is reported to be 21.9%.[4] It is unclear the impact of shivering during CD on 
blood pressure (BP) measurements;  
3. Patient discomfort during BP measurements, calf  > arm > ankle.[5]  
One study concluded there is poor correlation between arm and calf BP. They found calf BP was higher than 
arm BP, with an average difference in SBP of 18.3 ± 18.6 (95% CI: 14.0~22.6) before spinal anesthesia and 

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
3 
14.2 ± 21.0 (95% CI: 9.4~19.1) before incision/after spinal, and average difference in MAP of 4.8 ± 11.8 
(95% CI: 2.1~7.6) before spinal anesthesia and 0.1 ± 13.6 (95% CI: 2.1~7.6) before incision/after spinal 
anesthesia.[6] In contrast, another study of healthy non pregnant volunteers demonstrated insignificant 
differences in average SBP differences (22.4 [95% CI: -2.7~47.4]) and average MAP differences (3.7 [95% 
CI: -12.3~ 19.7]) among both ankles and arm.[5] A recent study reported the incidence of maternal systolic 
hypotension at 5 min post-SAB to be 16.7% in the LUD group and 53.3% in the non-LUD group.[7] However, 
imaging findings have not existed in MRI studies with low risk parturients but possible at high-risk for SHS 
[8, 9] who may benefit from LUD and other aggressive preventive measures to avoid undesired 
consequences.[10, 11]  
Nevertheless, none of studies have discussed issues related to SAB, LUD, SHS, and differences of between 
arm and ankle BP comprehensively. There are also the issues of sidedness of ankle BP measurements, as 
LUD tilts the body to the left side which may contribute to differences between arm and ankle BP.  
Specific Aims  
- 
To validate the effectiveness of LUD after SAB with simultaneous measurements of BP on the 
arm and left ankle during surgery in patients undergoing cesarean delivery (CD) at The Ohio State 
University Wexner Medical Center  
- 
To determine whether ankle BP correlates more accurately than arm SBP with the incidence of 
nausea/vomiting and category II or III fetal heart tracing and bradycardia after SAB and LUD 
under no shivering conditions in patients undergoing C-Section at The Ohio State University 
Wexner Medical Center  
- 
To determine the impact of body mass index and antepartum estimation of newborn weight on 
SHS[12] after the SAB   
MATERIALS AND METHODS 
Location:  
The OSUWMC Labor & Delivery  
Null Hypothesis:  
The magnitude of the differences in arm and ankle SBP is consistent before and after spinal 
anesthesia.  
Study design:  
 
A single center prospective self-control study. 
Study population: eligibility will be determined by the inclusion/exclusion criteria specified below. 
After eligibility has been confirmed, data from up to 100 subjects will be enrolled.  
 
Inclusion Criteria:  
a. Age ≥ 18 years old 

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
4 
b. Women undergoing cesarean delivery at The Ohio State University Wexner Medical Center under 
spinal anesthesia 
c. American Society of Anesthesiologists Physical Status I-III 
d. Body mass index during pregnancy ≥ 35 kg/m2 
e. Able to consent in English language 
f. Singleton pregnancy 
 
Exclusion criteria:  
a. Women undergoing elective cesarean delivery at The Ohio State University Wexner Medical Center 
under anesthesia other than spinal anesthesia (i.e. general and/or epidural anesthesia) 
b. Prisoners 
 
Sample size:  
For this pilot study, a sample size of 100 patients will offer valuable information on clinical outcomes 
for future randomized clinical trials on blood pressure monitoring in patients undergoing C-Section under 
SAB. 
 
Outcomes: 
● Primary outcome: difference of SBP measured between arm and ankle during elective CD before and 
after (pre-incision) SAB 
● Secondary outcomes: incidence of nausea, vomiting and shivering, estimated blood lost, blood 
transfusion (e.g. packed red blood cells units), category II or III fetal heart tracing, fetal bradycardia, 
APGAR at 1 min and 5 min, neonatal intensive care unit admission rate, SBP differences between 
arm and ankle before and after LUD performed in before surgery and anesthesia (baseline), after 
spinal anesthesia, after the fetus delivered 
Statistics: 
Maternal and newborn parameters (e.g. age, weight, height, body mass index, gravida and parity, 
gestational age, newborn weight, and high-risk obstetrics factors), clinical parameters (e.g. degree of tilt, 
compression, and incidence of shivering) will be summarized using descriptive statistics (mean/standard 
deviation, median/IQR, frequencies/proportions) based on data characteristics.   
In addition, descriptive statistics will be used to summarize differences between arm and ankle blood 
pressures taken at different time-points.  Multivariable linear regression models will be used to evaluate 
associations between changes in the magnitude of difference in SBP/MAP measures from different time-
points taking clinical factors such as degree of tilt, compression, shivering, and baby weight into account. 
A Bland-Altman plot for arm and left ankle paired SBP  taken during CD under spinal anesthesia will 
be created to identify bias and estimate 95% agreement limits.[6, 14, 15, 16] SBP and MAP will be obtained at 6 
data collection points preoperatively/pre-spinal with and without LUD, after SAB in supine position and 
LUD, and right after the fetus delivery in LUD, and supine after the delivery.   

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
5 
Data collection:  
1. Demographic data: age, weight, height, gestational age, newborn weight, HROB factors, locations of 
placenta, past medical history (i.e. cardiovascular disease), and circumferences of arm and ankle for 
BP measurements 
2. Systolic and Mean Arterial Blood Pressure: measured concomitantly at different time points on arm 
(standard of care) and left ankle (research purposes) 
a. Pre-spinal: supine and after LUD with 15° tilt [17] (≥ 1 measurement as required by standard 
of care) 
b. Post-spinal: supine and after LUD (≥ 1 measurement as required by standard of care) 
c. After delivery: supine and after LUD (≥ 1 measurement as required by standard of care) 
d. Incidence of intraoperative shivering, nausea/vomiting, category II or III fetal heart tracing, 
fetal Bradycardia, intubation, and neonatal intensive care unit admission after cesarean 
delivery  
3. Newborn’s clinical variables documented in the medical records as standard of care (e.g. heart rate 
and APGARs at 1 min and 5 min) 
4. Cord blood pH (if performed by standard of care) 
 
Study procedures:  
● Cuff size: large BP cuffs will be the default size for both arm and ankle measurements, but can be 
changed as clinically indicated based on circumferences of limbs 
● Cuff location: BP cuffs will be placed on the contralateral arm to the main peripheral IV following 
standard procedures. Left ankle cuff will be placed underneath intermittent pneumatic compression 
cuffs 
● Spinal anesthesia will be administered following standard of care anesthesia management for patients 
undergoing cesarean delivery at The OSUWMC 
● Hypotension avoidance strategies (e.g. phenylephrine infusion beginning at 50 mcg/kg/min) will be 
implemented per anesthesia provider clinical criteria 
● Fetal monitoring will be implemented as required by standard of care practices in patients undergoing 
cesarean delivery at The OSUWMC  
● Ankle blood pressure monitor screen will be covered. Thus, anesthesia providers will not be able to 
make any clinical decisions based on ankle blood pressures but arm blood pressure (standard) instead.  
ANTICIPATED IMPACT 
Placement of BP cuffs on left ankle during CD after SAB may become standard of care and provide more 
comfort than the current standard of care. The difference between SBP or MAP in patients positioned supine 
and after LUD before SAB may become a simple method to identify parturients at high-risk for SHS and 
prevent perioperative complications.  
ADVERSE 
EVENTS 
OR 
UNANTICIPATED 
PROBLEMS 
INVOLVING 
RISK 
TO 
PARTICIPANTS OR OTHERS 

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
6 
Any patient privacy/confidentiality breach will be recorded and reported following our Institutional Review 
Board (IRB) guidelines. 
RISKS 
No research-related invasive monitoring techniques/procedures are required in our study. Blood pressure 
values will be collected during surgery by IRB approved researchers.  Demographics and past medical history 
will be collected from electronic medical records as documented per standard of care by health care 
providers. Breach of confidentiality is the only recognized risk. To protect patient privacy, a limited data set 
will be created. During data collection, team members will remove any patient identifiers except for the 
codified database which will be stored on a password secured OSUWMC server. Moreover, any paper 
documents will be locked in our research’s office (Department of Anesthesiology, Clinical Research Office, 
The OSUWMC). All data will only be available to the PI and designated research personnel.  
PRIVACY/CONFIDENTIALITY ISSUES 
All reasonable efforts will be made to keep a patient’s protected health information (PHI) private and 
confidential.  There will be limited access to medical records and codification of all records.  Federal privacy 
guidelines will be followed when using or sharing PHI. 
Data will be stored electronically in our Department encrypted L-drive which is password protected and 
available only to IRB approved research personnel working on this study. The Ohio State University PCs 
have been compatible to the latest institutional Information System security policies. Computer databases 
will be maintained on password protected OSUWMC PCs at the Clinical research Office, Department of 
Anesthesiology (410 W 10th Ave. Doan Hall 520, Columbus, OH 43210).    
All study staff have completed required institutional education regarding patient confidentiality, Good 
Clinical Practices, Human Subjects Protection and Responsible Conduct of research trainings as required by 
Office of Responsible Research Practices (ORRP).  
RECORD RETENTION 
Research Records will be retained for a period of six (6) years after the submission of the final report and 
close-out procedures on the research project for which the Research Records were prepared. The retention 
of the original Research Records shall be the responsibility of the Principal Investigator. 
 
 

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
7 
REFERENCES 
1. Klöhr S, Roth R, Hofmann T, Rossaint R, Heesen M. Definitions of hypotension after spinal 
anaesthesia for caesarean section: literature search and application to parturients. Acta 
Anaesthesiologica Scandinavica. 2010 Sep;54(8):909-21 
2. Hartmann B, Junger A, Klasen J, Benson M, Jost A, Banzhaf A, Hempelmann G. The incidence and 
risk factors for hypotension after spinal anesthesia induction: an analysis with automated data 
collection. Anesthesia & Analgesia. 2002 Jun 1;94(6):1521-9. 
3. Bijker JB, van Klei WA, Kappen TH, van Wolfswinkel L, Moons KG, Kalkman CJ. Incidence of 
intraoperative hypotension as a function of the chosen DefinitionLiterature definitions applied to a 
retrospective cohort using automated data collection. Anesthesiology: The Journal of the American 
Society of Anesthesiologists. 2007 Aug 1;107(2):213-20. 
4. Wódarski B, Chutkowski R, Banasiewicz J, Moorthi K, Wójtowicz S, Malec‐Milewska M, Iohom G. 
Risk factors for shivering during caesarean section under spinal anaesthesia. A prospective 
observational study. Acta Anaesthesiologica Scandinavica. 2020 Jan;64(1):112-6. 
5. Moore C, Dobson A, Kinagi M, Dillon B. Comparison of BP measured at the arm, ankle and calf. 
Anaesthesia. 2008 Dec;63(12):1327-31. 
6. Zahn J, Bernstein H, Hossain S, Bodian C, Beilin Y. Comparison of non-invasive BP measurements 
on the arm and calf during cesarean delivery. Journal of clinical monitoring and computing. 2000 
Nov 1;16(8):557-62 
7. Chungsamarnyart Y, Wacharasint P, Carvalho B. Hemodynamic profiles with and without left uterine 
displacement: A randomized study in term pregnancies receiving subarachnoid blockade for cesarean 
delivery. Journal of Clinical Anesthesia. 2020 Sep 1;64:109796. 
8. Higuchi H, Takagi S, Zhang K, Furui I, Ozaki M. Effect of lateral tilt angle on the volume of the 
abdominal aorta and inferior vena cava in pregnant and nonpregnant women determined by magnetic 
resonance imaging. Anesthesiology: The Journal of the American Society of Anesthesiologists. 2015 
Feb 1;122(2):286-93. 
9. Kienzl D, Berger-Kulemann V, Kasprian G, Brugger PC, Weber M, Bettelheim D, Pusch F, Prayer 
D. Risk of inferior vena cava compression syndrome during fetal MRI in the supine position–a 
retrospective analysis. Journal of perinatal medicine. 2014 May 1;42(3):301-6. 
10. Mendonca, C , Griffiths, J , Ateleanu, B , Collis, RE. Hypotension following combined spinal-
epidural anaesthesia for Caesarean section: left lateral position vs, tilted supine position. Anaesthesia 
2003; 58:428–431. 

Protocol #: 2020H0502 
Protocol version: 1.0  
Approval date: 14-MAR-2021 
 
8 
11. Ngan Kee, WD , Khaw, KS , Ng, FF. Prevention of hypotension during spinal anesthesia for cesarean 
delivery. An effective technique using combination phenylephrine infusion and crystalloid 
cohydration. Anesthesiology 2005; 103:744–750 
12. De‐Giorgio, F., Grassi, V. M., Vetrugno, G., d’Aloja, E., Pascali, V. L., & Arena, V. (2012). Supine 
hypotensive syndrome as the probable cause of both maternal and fetal death. Journal of forensic 
sciences, 57(6), 1646-1649. 
13. Harvey NL, Hodgson RL, Kinsella SM. Does body mass index influence the degree of pelvic tilt 
produced by a Crawford wedge?. International Journal of Obstetric Anesthesia. 2013 Apr 
1;22(2):129-32. 
14. Ross VH, Dean LS, Thomas JA, Harris LC, Pan PH. A randomized controlled comparison between 
combined spinal-epidural and single-shot spinal techniques in morbidly obese parturients undergoing 
cesarean delivery: time for initiation of anesthesia. Anesthesia & Analgesia. 2014 Jan 1;118(1):168-
72. 
15. Drake MJ, Hill JS. Observational study comparing non‐invasive BP measurement at the arm and 
ankle during caesarean section. Anaesthesia. 2013 May;68(5):461-6. 
16. Sanghera S, North A, Abernethy S, Wrench I. Arm and ankle BP during caesarean section. 
International Journal of Obstetric Anesthesia. 2006 Jan 1;15(1):24-7. 
17. Rees, SGO , Thurlow, JA , Gardner, IC , Scrutton, MJL , Kinsella, SM. Maternal cardiovascular 
consequences of positioning after spinal anaesthesia for Caesarean section: left 15° table tilt vs. left 
lateral. Anaesthesia 2002; 57:15–20.